1
|
Geochemical and mineralogical assessment of sedimentary limestone mine waste and potential for mineral carbonation. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2021; 43:2065-2080. [PMID: 33392897 DOI: 10.1007/s10653-020-00784-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
This paper attempts to evaluate the mineralogical and chemical composition of sedimentary limestone mine waste alongside its mineral carbonation potential. The limestone mine wastes were recovered as the waste materials after mining and crushing processes and were analyzed for mineral, major and trace metal elements. The major mineral composition discovered was calcite (CaCO3) and dolomite [CaMg(CO3)2], alongside other minerals such as bustamite [(Ca,Mn)SiO3] and akermanite (Ca2MgSi2O7). Calcium oxide constituted the greatest composition of major oxide components of between 72 and 82%. The presence of CaO facilitated the transformation of carbon dioxide into carbonate form, suggesting potential mineral carbonation of the mine waste material. Geochemical assessment indicated that mean metal(loid) concentrations were found in the order of Al > Fe > Sr > Pb > Mn > Zn > As > Cd > Cu > Ni > Cr > Co in which Cd, Pb and As exceeded some regulatory guideline values. Ecological risk assessment demonstrated that the mine wastes were majorly influenced by Cd as being classified having moderate risk. Geochemical indices depicted that Cd was moderately accumulated and highly enriched in some of the mine waste deposited areas. In conclusion, the limestone mine waste material has the potential for sequestering CO2; however, the presence of some trace metals could be another important aspect that needs to be considered. Therefore, it has been shown that limestone mine waste can be regarded as a valuable feedstock for mineral carbonation process. Despite this, the presence of metal(loid) elements should be of another concern to minimize potential ecological implication due to recovery of this waste material.
Collapse
|
2
|
Responses of Ammonia-Oxidizing Archaea and Bacteria in Malodorous River Sediments to Different Remediation Techniques. MICROBIAL ECOLOGY 2021; 81:314-322. [PMID: 32935184 DOI: 10.1007/s00248-020-01597-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
In this study, the joint use of high throughput sequencing, real-time quantitative PCR, and ammonia-oxidizing bacteria (AOB)-inhibiting allylthiourea was used to differentiate between the contributions of ammonia-oxidizing archaea (AOA) vs AOB to ammonia oxidation and ascertain how AOA and AOB responded to two widely used river remediation techniques (aeration and Ca(NO3)2 injection). Results showed that ammonia oxidation was largely attributed to ATU-sensitive AOB rather than AOA and Nitrosomonas was the predominant AOB-related genus (53.86%) in the malodorous river. The contribution of AOB to ammonia oxidation in the context of aeration and Ca(NO3)2 injection was 75.51 ± 2.77% and 60.19 ± 10.44%, respectively. The peak of AOB/AOA ratio and the marked increase of relative abundances of Nitrosomonas and Nitrosospira in aeration runs further demonstrated aeration favored the ammonia oxidation of AOB. Comparatively, Ca(NO3)2 injection could increase the ammonia oxidation contribution of AOA from 31.32 ± 6.06 to 39.81 ± 10.44% and was significantly correlated with Nitrosococcus of AOB (r = 0.796, p < 0.05), Candidatus_Nitrosopelagicus of AOA (r = 0.986, p < 0.01), and AOA Simpson diversity (r = - 0.791, p < 0.05). Moreover, Candidatus_Nitrosopelagicus was only present in Ca(NO3)2 runs. Taken together, Ca(NO3)2 was recognized as an important factor in mediating the growth and ecological niches of ammonia oxidizers.Graphical abstract.
Collapse
|
3
|
Manganese hyperaccumulation capacity of Ilex paraguariensis A. St. Hil. and occurrence of interveinal chlorosis induced by transient toxicity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 203:111010. [PMID: 32888587 DOI: 10.1016/j.ecoenv.2020.111010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 06/30/2020] [Accepted: 07/03/2020] [Indexed: 06/11/2023]
Abstract
Manganese (Mn) toxicity is common in plants grown on very acid soils. However, some plants species that grow in this condition can take up high amounts of Mn and are referred to as hyperaccumulating species. In this study, we evaluated the capacity of Ilex paraguariensis to accumulate Mn and the effect of excessive concentrations on plant growth and nutrition. For this, a container experiment was conducted using soils from different parent materials (basalt and sandstone), with and without liming, and at six doses of applied Mn (0, 30, 90, 270, 540 and 1,080 mg kg-1). Clonal plants grown for 203 days were harvested to evaluate yield, and leaf tissue samples were evaluated for Mn and other elements. Without liming and with high Mn doses, leaf Mn concentrations reached 13,452 and 12,127 mg kg-1 in sandstone and basalt soils, respectively; concentrations in excess of 10,000 mg kg-1 are characteristic of hyperaccumulating plants. Liming reduced these values to 7203 and 8030 mg kg-1. More plant growth accompanied increased Mn leaf concentrations, with a growth reduction noted at the highest dose in unlimed soils. Elemental distribution showed Mn presence in the mesophyll, primarily in vascular bundles, without high Mn precipitates. Interveinal chlorosis of young leaves associated with high Mn concentration and lower Fe concentrations was observed, especially in sandstone soil without liming. However, the occurrence of this symptom was not associated with decreased plant growth.
Collapse
|
4
|
Scheelite weathering and tungsten (W) mobility in historical oxidic-sulfidic skarn tailings at Yxsjöberg, Sweden. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:6180-6192. [PMID: 31865574 PMCID: PMC7044260 DOI: 10.1007/s11356-019-07305-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 12/05/2019] [Indexed: 06/10/2023]
Abstract
More knowledge of the geochemical behavior of tungsten (W) and associated contamination risks is needed. Therefore, weathering of scheelite (CaWO4) and secondary sequestration and transport of W to groundwater in historical skarn tailings and surface water downstream of the tailings were studied. The tailings contained 920 mg/kg W, primarily in scheelite. Mineralogical and geochemical analyses were combined to elucidate the geochemical behavior of W in the tailings, and water samples were taken monthly during 2018 to monitor its mobility. In the tailings, a large peak of W was found at 1.5 m depth. There, 30 wt%. of W was present in easily reducible phases, indicating former scheelite weathering. Currently, W is being released from scheelite to water-soluble phases at 2.5 m depth. The release of WO42- is hypothetically attributed to anion exchange with CO32- released from calcite neutralizing acid produced from pyrrhotite oxidation in the upper tailings and transported downwards to pH conditions > 7. Higher concentrations of dissolved W were found in the groundwater and particulate W in downstream surface water than in reference water, but they were lower than current contamination thresholds. Tungsten showed correlations with hydrous ferric oxides (HFO) in both the tailings and surface water.
Collapse
|
5
|
Abstract
Soil pH is a critical soil quality index and controls soil microbial activities, soil nutrient availability, and plant roots growth and development. The current study aims to evaluate various pedotransfer functions for predicting soil pH using different geochemical indices (CaO, ratios of Al2O3, Fe2O3, TiO2, SiO2, MgO, and K2O to CaO) in forest soils. Various models including empirical functions (quadratic, cubic, sigmoid, logarithmic) and artificial neural network with these geochemical indices were assessed by independent testing set. Mean bias error (MBE), root mean square error (RMSE), mean absolute percentage error (MAPE), mean absolute error (MAE), coefficient of determination (R2), t-statistics (t-stat), and Akaike's Information Criterion (AIC) were applied to evaluate the model performances. Additionally, a new indicator (global performance indictor, GPI) was originally introduced in this study and was used to rank these models. According to GPI, the sigmoid functions and ANNs performed better than others. On average, they could explain above 70% of the variability in soil pH. Both model structure and dataset shape impact on model performance. The best input was CaO for ANNs, sigmoid, and logarithmic functions. The ratios of K2O to CaO and Al2O3 to CaO were the best inputs for quadratic and cubic equations, respectively.
Collapse
|
6
|
Study on the denitrification performance of Fe xLa yO z/activated coke for NH 3-SCR and the effect of CO escaped from activated coke at mid-high temperature on catalytic activity. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:20248-20263. [PMID: 31098908 DOI: 10.1007/s11356-019-05090-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 04/04/2019] [Indexed: 06/09/2023]
Abstract
Currently, activated coke is widely used in the removal of multiple pollutants from industrial flue gas. In this paper, a series of novel FexLayOz/AC catalysts was prepared by the incipient wetness impregnation for NH3-SCR denitrification reaction. The introduction of Fe-La bimetal oxides significantly improved the denitrification performance of activated coke at mid-high temperature, and 4% Fe0.3La0.7O1.5/AC exhibited a superior NOx conversion efficiency of 90.1% at 400 °C. The catalysts were further characterized by BET, SEM, XRD, Raman, EPR, XPS, FTIR, NH3-TPD, H2-TPR, et al., whose results showed that the perovskite-type oxide of LaFeO3 and oxygen vacancies were produced on the catalysts' surfaces during roasting. Fe-La doping enhanced the amount of acid sites (mainly Lewis and other stronger acid sites) and the content of multifarious oxygen species, which were beneficial for NOx removal at mid-high temperature. Moreover, it was investigated that the effect of released CO from activated coke at mid-high temperature on the NOx removal through the lifetime test, in which it was found that a large amount of CO produced by pyrolysis of activated coke could promote the NOx removal, and long-term escaping of CO on the activated coke carrier did not have a significant negative impact on catalytic performance. The results of the TG-IR test showed that volatile matter is released from the activated coke while TG results showed that the weight loss rate of 4% Fe0.3La0.7O1.5/AC only was 0.0015~0.007%/min at 300-400 °C. Hence, 4% Fe0.3La0.7O1.5/AC had excellent thermal stability and denitrification performance to be continuously used at mid-high temperature. Finally, the mechanisms were proposed on the basis of experiments and characterization results.
Collapse
|
7
|
Acid deposition induced base cation loss and different responses of soils and sediments in Taihu Lake watershed, China. CHEMOSPHERE 2019; 226:149-158. [PMID: 30928714 DOI: 10.1016/j.chemosphere.2019.03.136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 03/17/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
Acid deposition and algae blooms have resulted in great changes in the water chemistry of Taihu Lake; however, there have been few calculated results to describe these processes. Here we used a mass balance model to estimate base cation losses and evaluate the model applicability in this intensively human-impacted watershed based on a long-term database (1985-2015). The results showed that carbonate weathering induced Ca2+ and Mg2+ losses in the watershed were responsible for the increased ion net reaction (INR) of Ca2+and Mg2+ in the lake. While the increase of K+ and Na+ were not appropriate to provide independents check on the mass balance model because they generally entered the lake as human discharges, not reflecting change of the geochemical process in the watershed as the watershed dominant bedrock is carbonate but not silicate. Acid deposition in Taihu region caused decrease in pH, lime potential, and different Ca, Mg species of surface soils. Our field measurements of sediments in the two lake parts showed that the sediment lime potential was significantly higher in the algae dominated lake area than in the hydrophyte-dominated area due to the in-lake alkalinization by algae blooms, indicating that algae blooms played a significant role in the acidification resistance. Meanwhile, the measured lime potential of the watershed soils was lower than that of the sediment, implying a potential risk of acidification in the watershed. This research helps understand the accelerated interactions between human activities and natural geochemical processes and accelerated water chemistry change at the watershed level.
Collapse
|
8
|
Agricultural lime disturbs natural strontium isotope variations: Implications for provenance and migration studies. SCIENCE ADVANCES 2019; 5:eaav8083. [PMID: 30891501 PMCID: PMC6415960 DOI: 10.1126/sciadv.aav8083] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/29/2019] [Indexed: 06/01/2023]
Abstract
The application of 87Sr/86Sr in prehistoric mobility studies requires accurate strontium reference maps. These are often based from present-day surface waters. However, the use of agricultural lime in low to noncalcareous soils can substantially change the 87Sr/86Sr compositions of surface waters. Water unaffected by agriculture in western Denmark has an average 87Sr/86Sr ratio of 0.7124 as compared to an average of 0.7097 in water from nearby farmland. The 87Sr/86Sr ratio obtained from samples over 1.5 km along a stream, which originates in a forest and flows through lime-treated farmland, decreased from 0.7131 to 0.7099. Thus, 87Sr/86Sr-based mobility and provenance studies in regions with low to noncalcareous soils should be reassessed. For example, reinterpreting the iconic Bronze Age women at Egtved and Skrydstrup using values unaffected by agricultural lime indicates that it is most plausible that these individuals originated close to their burial sites and not far abroad as previously suggested.
Collapse
|
9
|
Blends of lemongrass derivatives and lime for the preparation of mixed beverages: antioxidant, physicochemical, and sensory properties. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2019; 99:1302-1310. [PMID: 30094839 DOI: 10.1002/jsfa.9305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 07/23/2018] [Accepted: 08/03/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Lemongrass is an aromatic plant with antioxidant and antimicrobial properties, used for the preparation of medicinal tea and for essential oil production. Previous studies have shown that extracts of lemongrass leaves contain phenolic compounds associated with health benefits. Although essential oils have been widely used as flavoring agents, there is no scientific evidence regarding the use of lemongrass essential oils in beverages. Thus, the objectives of the present study were to develop blends with lemongrass derivatives (aqueous extract, lyophilized extract, and essential oil) and lime juice for the preparation of mixed beverages, to evaluate the antioxidant and physicochemical characteristics of blends, and to determine the sensory profile and acceptance of mixed beverages. RESULTS The formulated blends showed favorable physicochemical characteristics such as acidity and color, and they contained bioactive compounds (phenolics and vitamin C) and important antioxidant properties. Mixed beverages prepared from blends containing aqueous extract or lyophilized extract plus essential oil, which showed higher intensity of lemongrass aroma and flavor, were more readily accepted. CONCLUSION This study demonstrates that it is possible to make suitable blends with lemongrass derivatives and lime juice for the preparation of high-quality mixed beverages with sensory pleasantness, and potentially beneficial health components. © 2018 Society of Chemical Industry.
Collapse
|
10
|
Control efficacy of Ca-containing foliar fertilizers on bitter pit in bagged 'Fuji' apple and effects on the Ca and N contents of apple fruits and leaves. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2018; 98:5435-5443. [PMID: 29675868 DOI: 10.1002/jsfa.9087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 01/29/2018] [Accepted: 04/20/2018] [Indexed: 05/26/2023]
Abstract
BACKGROUND The preharvest application of Ca-containing foliar fertilizers can reduce the incidence of bitter pit (BP) in apples and improve fruit quality by increasing the Ca content and decreasing both the N content and the N/Ca ratio in fruits. In this study, we aimed to investigate the control efficacy of Ca-containing fertilizers on the incidence of BP and their effects on the Ca and N contents in bagged 'Fuji' apples by spraying foliar fertilizer containing calcium chloride (CaCl2 ), calcium nitrate [Ca(NO3 )2 ] or calcium formate [Ca(HCOO)2 ] at an early stage, five days after full bloom (DAFB) and 40 DAFB, and at a late stage, 80 DAFB and 125 DAFB. RESULTS The incidences of BP were reduced significantly by 43.2-73.0%, and the efficacy of spraying at an early stage was significantly higher than that of spraying at a late stage. The Ca content of bagged apple fruits increased whereas the N content and N/Ca ratio decreased after spraying Ca-containing foliar fertilizers; however, the Ca content, N content and N/Ca ratio of apple leaves were differentially influenced. CONCLUSION Foliar fertilizer containing CaCl2, Ca(NO3 )2 or Ca(HCOO)2 can be used at an early stage to control BP in apple and improve the quality of bagged apple fruits. © 2018 Society of Chemical Industry.
Collapse
|
11
|
Performance and adsorption mechanism of a magnetic calcium silicate hydrate composite for phosphate removal and recovery. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2018; 2017:578-591. [PMID: 29851411 DOI: 10.2166/wst.2018.184] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A novel magnetic calcium silicate hydrate composite (Fe3O4@CSH) was proposed for phosphorus (P) removal and recovery from a synthetic phosphate solution, facilitated by a magnetic separation technique. The Fe3O4@CSH material was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta-potential and magnetic curves. The chemical composition and structure of Fe3O4@CSH and the successful surface loading of hydroxyl functional groups were confirmed. Phosphate adsorption kinetics, isotherm, and thermodynamic experiments showed that adsorption reaches equilibrium at 24 h, with a maximum adsorption capacity of 55.84 mg P/g under optimized experimental conditions. Adsorption kinetics fitted well to the pseudo second-order model, and equilibrium data fit the Freundlich isotherm model. Thermodynamic analysis provided a positive value for ΔH° (129.84 KJ/mol) and confirmed that phosphate adsorption on these materials is endothermic. The P-laden Fe3O4@CSH materials could be rapidly separated from aqueous solution by a magnetic separation technique within 1 min. A removal rate of more than 60% was still obtained after eight adsorption/desorption cycles, demonstrating the excellent reusability of the particles. The results demonstrated that the Fe3O4@CSH materials had high P-adsorption efficiency and were reusable.
Collapse
|
12
|
Utilization of calcium-based and aluminum-based materials for the treatment of stabilized landfill leachate: a comparative study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:26821-26828. [PMID: 28963598 DOI: 10.1007/s11356-017-0264-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 09/19/2017] [Indexed: 06/07/2023]
Abstract
This study explored the efficiencies and mechanisms of refractory organic matters removal in the stabilized landfill leachate by adding different reagents. Calcium-based and aluminum-based materials were added into the leachate as comparing experiments. XRD, FTIR, and EEM were adopted to analyze the solid products and leachate. As a result, the in situ synthesized CaAl-LDHs were more beneficial for refractory organic matters removal, especially for benzodiazepines. When CaAl-LDHs were formed, the removal efficiencies of COD, UV254, and TOC were best and achieved 58.48, 81.22, and 71.30%, respectively. For fluorescent substances, humic acid-like and fulvic acid-like compounds were efficiently removed by CaAl-LDHs. In particular, CaAl-LDHs had selective removal effects on fulvic acid-like compounds, which were characteristic of small molecular weight and major carboxyl groups.
Collapse
|
13
|
The utilization of waste by-products for removing silicate from mineral processing wastewater via chemical precipitation. WATER RESEARCH 2017; 125:318-324. [PMID: 28869882 DOI: 10.1016/j.watres.2017.08.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/11/2017] [Accepted: 08/20/2017] [Indexed: 06/07/2023]
Abstract
This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater. Chemical precipitation is used to remove silicate from scheelite (CaWO4) cleaning flotation wastewater and the waste by-products are used as a substitute for calcium chloride (CaCl2). A series of laboratory experiments is conducted to explain the removal of silicate and the characterization and formation mechanism of calcium silicate. The results show that silicate removal reaches 90% when the Ca:Si molar ratio exceeds 1.0. The X-ray diffraction (XRD) results confirm the characterization and formation of calcium silicate. The pH is the key factor for silicate removal, and the formation of polysilicic acid with a reduction of pH can effectively improve the silicate removal and reduce the usage of calcium. The economic analysis shows that the treatment costs with waste acid (0.63 $/m3) and waste alkali (1.54 $/m3) are lower than that of calcium chloride (2.38 $/m3). The efficient removal of silicate is confirmed by industrial testing at a plant. The results show that silicate removal reaches 85% in the recycled water from tailings dam.
Collapse
|
14
|
Haemolytic activity of soil from areas of varying podoconiosis endemicity in Ethiopia. PLoS One 2017; 12:e0177219. [PMID: 28493920 PMCID: PMC5426718 DOI: 10.1371/journal.pone.0177219] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 04/24/2017] [Indexed: 02/05/2023] Open
Abstract
Background Podoconiosis, non-filarial elephantiasis, is a non-infectious disease found in tropical regions such as Ethiopia, localized in highland areas with volcanic soils cultivated by barefoot subsistence farmers. It is thought that soil particles can pass through the soles of the feet and taken up by the lymphatic system, leading to the characteristic chronic oedema of the lower legs that becomes disfiguring and disabling over time. Methods The close association of the disease with volcanic soils led us to investigate the characteristics of soil samples in an endemic area in Ethiopia to identify the potential causal constituents. We used the in vitro haemolysis assay and compared haemolytic activity (HA) with soil samples collected in a non-endemic region of the same area in Ethiopia. We included soil samples that had been previously characterized, in addition we present other data describing the characteristics of the soil and include pure phase mineral standards as comparisons. Results The bulk chemical composition of the soils were statistically significantly different between the podoconiosis-endemic and non-endemic areas, with the exception of CaO and Cr. Likewise, the soil mineralogy was statistically significant for iron oxide, feldspars, mica and chlorite. Smectite and kaolinite clays were widely present and elicited a strong HA, as did quartz, in comparison to other mineral phases tested, although no strong difference was found in HA between soils from the two areas. The relationship was further investigated with principle component analysis (PCA), which showed that a combination of an increase in Y, Zr and Al2O3, and a concurrent increase Fe2O3, TiO2, MnO and Ba in the soils increased HA. Conclusion The mineralogy and chemistry of the soils influenced the HA, although the interplay between the components is complex. Further research should consider the variable biopersistance, hygroscopicity and hardness of the minerals and further characterize the nano-scale particles.
Collapse
|
15
|
A three-season field study on the in-situ remediation of Cd-contaminated paddy soil using lime, two industrial by-products, and a low-Cd-accumulation rice cultivar. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 136:135-141. [PMID: 27863309 DOI: 10.1016/j.ecoenv.2016.11.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/10/2016] [Accepted: 11/12/2016] [Indexed: 06/06/2023]
Abstract
To mitigate the serious problem of Cd-contaminated paddy soil, we investigated the remediation potential of combining in-situ immobilization with a low-Cd-accumulation rice cultivar. A three-season field experiment compared the soil pH, available Cd and absorption of Cd by three rice cultivars with different Cd accumulation abilities grown in Cd-contaminated paddy soil amended with lime (L), slag (S), and bagasse (B) alone or in combination. The three amendments applied alone and in combination significantly increased soil pH, reduced available Cd and absorption of Cd by rice with no effect on grain yield. Among these, the LS and LSB treatments reduced the brown rice Cd content by 38.3-69.1% and 58.3-70.9%, respectively, during the three seasons. Combined with planting of a low-Cd-accumulation rice cultivar (Xiang Zaoxian 32) resulted in a Cd content in brown rice that met the contaminant limit (≤0.2mgkg-1). However, the grain yield of the low-Cd-accumulation rice cultivar was approximately 30% lower than the other two rice cultivars. Applying LS or LSB as amendments combined with planting a low-Cd-accumulation rice cultivar is recommended for the remediation of Cd-contaminated paddy soil. The selection and breeding of low-Cd-accumulation rice cultivars with high grain production requires further research.
Collapse
|
16
|
Quantitative Evaluation of MDP-Ca Salt and DCPD after Application of an MDP-based One-step Self-etching Adhesive on Enamel and Dentin. THE JOURNAL OF ADHESIVE DENTISTRY 2017; 18:205-13. [PMID: 27200430 DOI: 10.3290/j.jad.a36133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE To investigate the effects of an experimental 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based one-step self-etching adhesive (EX adhesive) applied to enamel and dentin on the production of calcium salt of MDP (MDP-Ca salt) and dicalcium phosphate dehydrate (DCPD) at various periods. MATERIALS AND METHODS The EX adhesive was prepared. Bovine enamel and dentin reactants were prepared by varying the application period of the EX adhesive: 0.5, 1, 5, 30, 60 and 1440 min. Enamel and dentin reactants were analyzed using x-ray diffraction and solid-state phosphorus-31 nuclear magnetic resonance (31P NMR). Curvefitting analyses of corresponding 31P NMR spectra were performed. RESULTS Enamel and dentin developed several types of MDP-Ca salts and DCPDs with amorphous and crystalline phases throughout the application period. The predominant molecular species of MDP-Ca salt was determined as the monocalcium salt of the MDP monomer. Dentin showed a faster production rate and greater produced amounts of MDP-Ca salt than did enamel, since enamel showed a knee-point in the production rate of the MDP-Ca salt at the application period of 5 min. In contrast, enamel developed greater amounts of DCPD than did dentin and two types of DCPDs with different crystalline phases at application periods > 30 min. The amounts of MDP-Ca salt developed during the 30-s application of the EX adhesive on enamel and dentin were 7.3 times and 21.2 times greater than DCPD, respectively. CONCLUSION The MDP-based one-step adhesive yielded several types of MDP-Ca salts and DCPD with an amorphous phase during the 30-s application period on enamel and dentin.
Collapse
|
17
|
Mechanism of Calcium Lactate Facilitating Phytic Acid Degradation in Soybean during Germination. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:5564-73. [PMID: 27324823 DOI: 10.1021/acs.jafc.6b01598] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Calcium lactate facilitates the growth and phytic acid degradation of soybean sprouts, but the mechanism is unclear. In this study, calcium lactate (Ca) and calcium lactate with lanthanum chloride (Ca+La) were used to treat soybean sprouts to reveal the relevant mechanism. Results showed that the phytic acid content decreased and the availability of phosphorus increased under Ca treatment. This must be due to the enhancement of enzyme activity related to phytic acid degradation. In addition, the energy metabolism was accelerated by Ca treatment. The energy status and energy metabolism-associated enzyme activity also increased. However, the transmembrane transport of calcium was inhibited by La(3+) and concentrated in intercellular space or between the cell wall and cell membrane; thus, Ca+La treatment showed reverse results compared with those of Ca treatment. Interestingly, gene expression did not vary in accordance with their enzyme activity. These results demonstrated that calcium lactate increased the rate of phytic acid degradation by enhancing growth, phosphorus metabolism, and energy metabolism.
Collapse
|
18
|
Using Low Temperature Photoluminescence Spectroscopy to Investigate CH₃NH₃PbI₃ Hybrid Perovskite Degradation. Molecules 2016; 21:molecules21070885. [PMID: 27399669 PMCID: PMC6274278 DOI: 10.3390/molecules21070885] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 06/29/2016] [Accepted: 06/30/2016] [Indexed: 11/28/2022] Open
Abstract
Investigating the stability and evaluating the quality of the CH3NH3PbI3 perovskite structures is quite critical both to the design and fabrication of high-performance perovskite devices and to fundamental studies of the photophysics of the excitons. In particular, it is known that, under ambient conditions, CH3NH3PbI3 degrades producing some PbI2. We show here that low temperature Photoluminescence (PL) spectroscopy is a powerful tool to detect PbI2 traces in hybrid perovskite layers and single crystals. Because PL spectroscopy is a signal detection method on a black background, small PbI2 traces can be detected, when other methods currently used at room temperature fail. Our study highlights the extremely high stability of the single crystals compared to the thin layers and defects and grain boundaries are thought to play an important role in the degradation mechanism.
Collapse
|
19
|
Geochemical modeling and assessment of leaching from carbonated municipal solid waste incinerator (MSWI) fly ash. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:12107-12119. [PMID: 26965281 DOI: 10.1007/s11356-016-6320-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/16/2016] [Indexed: 06/05/2023]
Abstract
Municipal solid waste incinerator (MSWI) fly ashes are characterized by high calcium oxide (CaO) content. Carbon dioxide (CO2) adsorption by MSWI fly ash was discussed based on thermogravimetry (TG)/differential thermal analysis (DTA), minerology analysis, and adapting the Stenoir equation. TG/DTA analysis showed that the weight gain of the fly ash below 440 °C was as high as 5.70 %. An adapted Stenoir equation for MSWI fly ash was discussed. The chloride in MSWI fly ash has a major impact on CO2 adsorption by MSWI fly ash or air pollution control (APC) residues. Geochemical modeling of the critical trace elements copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), and antimony (Sb) before and after carbonation was performed using a thermodynamic equilibrium model for solubility and a surface complexation model for metal sorption. Leaching of critical trace elements was generally found to be strongly dependent on the degree of carbonation attained, and their solubility appeared to be controlled by several minerals. Adsorption on ferrum (Fe) and aluminum (Al) colloids was also responsible for removal of the trace elements Cd, Pb, and Sb. We used Hakanson's potential ecological risk index (HPERI) to evaluate the risk of trace element leaching in general. The results demonstrate that the ecological risk showed a V-shaped dependency on pH; the optimum pH of the carbonated fly ash was found to be 10.3-11, resulting from the optimum carbonation (liquid-to-solid (L/S) ratio = 0.25, carbonation duration = ∼30-48 h). The dataset and modeling results presented here provide a contribution to assessing the leaching behavior of MSWI fly ash under a wide range of conditions.
Collapse
|
20
|
Immobilization of trace elements in municipal solid waste incinerator (MSWI) fly ash by producing calcium sulphoaluminate cement after carbonation and washing. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2016; 34:184-194. [PMID: 26644396 DOI: 10.1177/0734242x15617846] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The possibility of producing calcium sulphoaluminate cement (CSA) by adding municipal solid waste incinerator (MSWI) fly ash to raw meal was investigated. After subjecting MSWI fly ash to accelerated carbonation and washing with water (ACW), various amounts (i.e., 5, 10 and 15 wt%) of the treated ash were added to raw meal composed of a mixture of bauxite, limestone and gypsum. The mixtures were sintered in a laboratory-scale muffle furnace at temperatures of 1250°, 1300°, 1325° and 1350 °C for various durations. The influence of different quantities of MSWI fly ash on the mineralogy, major phase composition and strength development of the resulting clinker was studied, as was the effect of ash treatments on leaching and volatilization of trace elements. The ACW treatment reduced the volatilization ratio of trace elements during the clinkerization process. Volatilization ratios for lead, cadmium and zinc were 21.5%, 33.6% and 16.3%, respectively, from the ACW fly ash treatment, compared with ratios of 97.5%, 93.1% and 85.2% from untreated fly ash. The volatilization ratios of trace elements were ordered as follows: untreated fly ash > carbonated fly ash > carbonated and water-washed fly ash. The ACW process also reduced the chloride content in the MSWI fly ash by 90 wt% and prevented high concentrations of trace elements in the effluents.
Collapse
|
21
|
[Risk assessment of rescue helicopter or ambulance transport of patients ingesting hazardous volatile materials]. CHUDOKU KENKYU : CHUDOKU KENKYUKAI JUN KIKANSHI = THE JAPANESE JOURNAL OF TOXICOLOGY 2016; 29:16-20. [PMID: 27255018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
INTRODUCTION In cases of transport by rescue helicopter or ambulance of patients having ingested hazardous substances, medical personnel may be at a certain risk of inhaling the substances. However, few reports have addressed such risk of causing secondary casualties. PURPOSE This simulation study aimed to assess the risk of inhalation of hydrogen sulfide and chlo-opicrin in the cabin of a helicopter or an ambulance transporting a patient who has ingested calcium polysulfide or chloropicrin, which were previously reported to cause secondary casualties. METHOD Concentrations of hydrogen sulfide and chloropicrin were assessed on the following as-umptions :The patient ingested 100 mL of the causative or original chemical. All chemical substances reacted with the gastric juice or were thoroughly vomited and evaporated uniformly within the cabin space of the helicopter or ambulance. Environmental conditions were 20 *degrees at 1 atmosphere of pres-ure in a 5 m3 cabin volume in the helicopter and a 13.5 m3 cabin volume in the ambulance. RESULTS In the case of calcium polysulfide ingestion which produced hydrogen sulfide, its concen-ration reached 774 ppm in the helicopter and 287 ppm in the ambulance. For chloropicrin ingestion, the concentrations were 4,824 ppm and 1,787 ppm, respectively. DISCUSSION The simulated concentration of hydrogen sulfide was more than 500 ppm in the heli-opter, which may lead to respiratory paralysis and death. The simulated concentration of chloropicrin was more than 300 ppm, which has a risk of death within 10 minutes. Currently, as far as Japanese laws are concerned, there are no restrictions requiring pretransport assessment or setting criteria for transporting patients who might have ingested hazardous substances that could cause secondary casu-lties when vomited. CONCLUSION When patients who might have ingested hazardous chemicals are transported, it is important to recognize the risk of causing secondary casualties by vomiting the chemicals.
Collapse
|
22
|
Assessment of waste oyster shells and coal mine drainage sludge for the stabilization of As-, Pb-, and Cu-contaminated soil. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:2362-2370. [PMID: 26411449 DOI: 10.1007/s11356-015-5456-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 09/17/2015] [Indexed: 06/05/2023]
Abstract
A novel treatment mix was designed for the simultaneous immobilization of As, Cu, and Pb in contaminated soils using natural (waste oyster shells (WOS)) and industrial (coal mine drainage sludge (CMDS)) waste materials. The treatments were conducted using the standard U.S. sieve size no. 20 (0.85 mm) calcined oyster shells (COS) and CMDS materials with a curing time of 1 and 28 days. The As immobilization treatments were evaluated using the 1-N HCl extraction fluid, whereas the Pb and Cu immobilization treatments were evaluated using the 0.1-N HCl extraction fluid based on the Korean leaching standards. The treatment results showed that the immobilization of As, Cu, and Pb was best achieved using a combination mix of 10 wt% COS and 10 wt% CMDS. This treatment mix was highly effective leading to superior leachability reductions for all three target contaminants (>93 % for As and >99 % for Cu and Pb) for a curing period of 28 days. The X-ray absorption near-edge structure (XANES) results showed that As was present in the form of As(V) in the control sample and that no changes in As speciation were observed following the COS-CMDS treatments. The scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) sample treated with 10 wt% COS and 10 wt% CMDS indicated that As immobilization may be associated with the formation of Ca-As and Fe-As precipitates while Pb and Cu immobilization was most probably linked to calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs).
Collapse
|
23
|
Amendment of biosolids with waste materials and lime: Effect on geoenvironmental properties and leachate production. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 46:165-175. [PMID: 26341830 DOI: 10.1016/j.wasman.2015.08.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/17/2015] [Accepted: 08/17/2015] [Indexed: 06/05/2023]
Abstract
Residuals from wastewater treatment operations (biosolids) were mixed with lime, fly ash, lime kiln dust, or two smelter slags to assess their efficacy as potential stabilisation agents by assessing their effects on the shear strength, compressibility, and solids content of mixtures. In addition, the minerals formed and leachate produced during stabilisation were determined. Tests were performed to explore the change of the geoenvironmental properties of the amended biosolids, while under pressure, at different scales using laboratory, pilot and field scale tests. The settlement characteristics of the amended biosolids under a range of applied pressures were determined using a consolidometer. All amended biosolids mixtures showed higher strength than the unamended biosolids, with mixtures containing a combination of 20% fly ash and 20% lime giving the highest (up to eightfold) increase in strength, and that with lime kiln dust and the smelter slags showing the lowest (up to twofold). The biosolids mixtures with only lime gave the second highest increase in strength (up to fourfold), but produced the largest amount of leachate, with higher level of dissolved calcium. The increase in strength correlated with availability of calcium oxide in the mixtures which lead to calcium carbonate formation, accompanied with higher leachate production and settlement during consolidation. Copper, nickel and zinc concentrations increased with alkaline additives and corresponded to higher pH and DOC levels. Nonetheless, concentrations were within the New Zealand regulatory limits for Class A landfills.
Collapse
|
24
|
Investigation into the use of cement kiln dust in high density sludge (HDS) treatment of acid mine water. WATER RESEARCH 2015; 85:443-450. [PMID: 26372742 DOI: 10.1016/j.watres.2015.08.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 08/25/2015] [Accepted: 08/30/2015] [Indexed: 06/05/2023]
Abstract
The purpose of this study was to investigate the potential to replace lime with cement kiln dust (CKD) in high density sludge (HDS) treatment of acid mine drainage (AMD). The bench-scale study used two water samples: AMD sampled from a lead-zinc mine with high concentrations of iron (Fe), zinc (Zn), and arsenic (As) (Fe/Zn-AMD) and a synthetic AMD solution (Syn-AMD) spiked with ferric sulfate (Fe2(SO4)3). Arsenic was found to be significantly reduced with CKD-HDS treatment of Fe/Zn-AMD compared to lime-HDS treatment, to concentrations below the stringent mine effluent discharge regulation of 0.10 mg As/L (i.e., 0.04 ± 0.02 mg/L). Both CKD- and lime-HDS treatment of the two AMD samples resulted in settled water Fe concentrations above the stringent discharge guideline of 0.3 mg Fe/L. CKD addition in the HDS process also resulted in high settled water turbidity, above typical discharge guidelines of 15 mg TSS/L. CKD-HDS treatment was found to result in significantly improved settled solids (i.e., sludge) quality compared to that generated in the lime-HDS process. HDS treatment with CKD resulted in 25-88% lower sludge volume indices, 2 to 9 times higher % wet solids, and 10 to 20 times higher % dry solids compared to lime addition. XRD and XPS testing indicated that CKD-HDS sludge consisted of mainly CaCO3 and SiO2 with Fe(3+) precipitates attached at particle surfaces. XRD and XPS testing of the lime-HDS generated sludge showed that it consisted of non-crystalline Fe oxides typical of sludge formed from precipitates with a high water concentration. Increased sedimentation rates were also found for CKD (1.3 cm/s) compared to lime (0.3 cm/s). The increased solids loading with CKD addition compared to lime addition in the HDS process was suggested to both promote surface complexation of metal precipitates with insoluble CKD particles and increase compression effects during Type IV sedimentation. These mechanisms collectively contributed to the reduced water content of CKD-HDS sludge. The results of this study suggest that solids loading is a significant factor in increased sludge density found with the HDS process compared to conventional lime precipitation-sedimentation.
Collapse
|
25
|
Leaching characteristics of calcium-based compounds in MSWI Residues: From the viewpoint of clogging risk. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 42:93-100. [PMID: 25934218 DOI: 10.1016/j.wasman.2015.04.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 04/03/2015] [Accepted: 04/07/2015] [Indexed: 06/04/2023]
Abstract
Leachate collection system (LCS) clogging caused by calcium precipitation would be disadvantageous to landfill stability and operation. Meanwhile, calcium-based compounds are the main constituents in both municipal solid waste incineration bottom ash (MSWIBA) and stabilized air pollution control residues (SAPCR), which would increase the risk of LCS clogging once these calcium-rich residues were disposed in landfills. The leaching behaviors of calcium from the four compounds and municipal solid waste incineration (MSWI) residues were studied, and the influencing factors on leaching were discussed. The results showed that pH was the crucial factor in the calcium leaching process. CaCO3 and CaSiO3 began leaching when the leachate pH decreased to less than 7 and 10, respectively, while Ca3(PO4)2 leached at pH<12. CaSO4 could hardly dissolve in the experimental conditions. Moreover, the sequence of the leaching rate for the different calcium-based compounds is as follows: CaSiO3>Ca3(PO4)2>CaCO3. The calcium leaching from the MSWIBA and SAPCR separately started from pH<7 and pH<12, resulting from CaCO3 and Ca3(PO4)2 leaching respectively, which was proven by the X-ray diffraction results. Based on the leaching characteristics of the different calcium compounds and the mineral phase of calcium in the incineration residues, simulated computation of their clogging potential was conducted, providing the theoretical basis for the risk assessment pertaining to LCS clogging in landfills.
Collapse
|
26
|
Recycled sand in lime-based mortars. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:2595-2602. [PMID: 25266158 DOI: 10.1016/j.wasman.2014.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 09/03/2014] [Accepted: 09/09/2014] [Indexed: 06/03/2023]
Abstract
The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime-pozzolan or lime-pozzolan-cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars' structure.
Collapse
|
27
|
Effect of water treatment additives on lime softening residual trace chemical composition--implications for disposal and reuse. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2014; 145:240-248. [PMID: 25073099 DOI: 10.1016/j.jenvman.2014.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 07/01/2014] [Accepted: 07/03/2014] [Indexed: 06/03/2023]
Abstract
Drinking water treatment residues (WTR) offer potential benefits when recycled through land application. The current guidance in Florida, US allows for unrestricted land application of lime softening WTR; alum and ferric WTR require additional evaluation of total and leachable concentrations of select trace metals prior to land application. In some cases a mixed WTR is produced when lime softening is accompanied by the addition of a coagulant or other treatment chemical; applicability of the current guidance is unclear. The objective of this research was to characterize the total and leachable chemical content of WTR from Florida facilities that utilize multiple treatment chemicals. Lime and mixed lime WTR samples were collected from 18 water treatment facilities in Florida. Total and leachable concentrations of the WTR were measured. To assess the potential for disposal of mixed WTR as clean fill below the water table, leaching tests were conducted at multiple liquid to solid ratios and under reducing conditions. The results were compared to risk-based soil and groundwater contamination thresholds. Total metal concentrations of WTR were found to be below Florida soil contaminant thresholds with Fe found in the highest abundance at a concentration of 3600 mg/kg-dry. Aluminum was the only element that exceeded the Florida groundwater contaminant thresholds using SPLP (95% UCL = 0.23 mg/L; risk threshold = 0.2 mg/L). Tests under reducing conditions showed elevated concentrations of Fe and Mn, ranging from 1 to 3 orders of magnitude higher than SPLP leachates. Mixed lime WTR concentrations (total and leachable) were lower than the ferric and alum WTR concentrations, supporting that mixed WTR are appropriately represented as lime WTR. Testing of WTR under reducing conditions demonstrated the potential for release of certain trace metals (Fe, Al, Mn) above applicable regulatory thresholds; additional evaluation is needed to assess management options where reducing conditions may develop.
Collapse
|
28
|
Ultrasonic-assisted production of biodiesel from transesterification of palm oil over ostrich eggshell-derived CaO catalysts. BIORESOURCE TECHNOLOGY 2014; 171:428-432. [PMID: 25226059 DOI: 10.1016/j.biortech.2014.08.102] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 08/21/2014] [Accepted: 08/23/2014] [Indexed: 06/03/2023]
Abstract
In this study, waste ostrich eggshell-derived calcium oxide (denoted as CaO(OE)) particles were synthesized and explored as cost-effective catalysts for the ultrasonic-assisted transesterification of palm oil. The physicochemical properties of the resultant catalysts were characterized by XRD, N2 adsorption, XRF and Hammett indicator, while the catalytic activity was evaluated through transesterification of palm oil with methanol under ultrasonic conditions. More specifically, the CaO(OE) showed comparable catalytic activity to the one derived from commercial calcium carbonate (denoted as CaO(Lab)). Moreover, under ultrasonic conditions, the catalytic activity of CaO(OE) could be enhanced significantly. The maximum yield of fatty acid methyl esters could reach 92.7% under the optimal condition of reaction time of 60 min with ultrasonic power of 60% (120 W), methanol-to-oil ratio of 9:1, and catalyst loading of 8 wt.%. The results indicated that the CaO(OE) catalysts showed good catalytic performance and reusability, and may potentially reduce the cost of biodiesel production.
Collapse
|
29
|
A randomized controlled trial: the efficacy of eluoride rinse combined with calcium pre-rinse to increase overnight salivary fluoride. Acta Odontol Scand 2014; 72:557-60. [PMID: 24304291 DOI: 10.3109/00016357.2013.859729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Previous studies have shown that a calcium (Ca) pre-rinse given before a 228 ppm fluoride (F) rinse greatly increased salivary fluoride. Objectives. The aim of this randomized controlled trial is to examine if Ca pre-rinse could increase the fluoride concentration in the overnight unstimulated saliva after a 905 ppm F-rinse. MATERIALS AND METHODS Pre-rinses containing 150 mM, 75 mM or 0 mM Ca-lactate prepared by a validated pharmaceutical cGPM procedure were tested by nine subjects in a randomized order immediately followed by a 905 ppm F-rinse. The fluoride concentration was measured in unstimulated saliva collected 10 h later. RESULTS AND CONCLUSIONS The Ca pre-treatment significantly increased F level in overnight saliva following the 905 ppm fluoride rinse by 1.7× relative to the 905 ppm F-rinse alone; however, a significant effect was only observed with the highest (150 mM) Ca concentration as pre-rinse. Clinical relevance. High concentration F rinses (905 ppm) are commonly recommended for patients at high-risk of caries. A pre-treatment with high levels of Ca may further improve the cariostatic effect of this ion.
Collapse
|
30
|
Solidification/stabilization of ash from medical waste incineration into geopolymers. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:1823-1828. [PMID: 24785364 DOI: 10.1016/j.wasman.2014.03.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 03/03/2014] [Accepted: 03/26/2014] [Indexed: 06/03/2023]
Abstract
In the present work, bottom and fly ash, generated from incinerated medical waste, was used as a raw material for the production of geopolymers. The stabilization (S/S) process studied in this paper has been evaluated by means of the leaching and mechanical properties of the S/S solids obtained. Hospital waste ash, sodium hydroxide, sodium silicate solution and metakaolin were mixed. Geopolymers were cured at 50°C for 24h. After a certain aging time of 7 and 28 days, the strength of the geopolymer specimens, the leachability of heavy metals and the mineralogical phase of the produced geopolymers were studied. The effects of the additions of fly ash and calcium compounds were also investigated. The results showed that hospital waste ash can be utilized as source material for the production of geopolymers. The addition of fly ash and calcium compounds considerably improves the strength of the geopolymer specimens (2-8 MPa). Finally, the solidified matrices indicated that geopolymerization process is able to reduce the amount of the heavy metals found in the leachate of the hospital waste ash.
Collapse
|
31
|
Distribution of trace elements in particle size fractions for contaminated soils by a copper smelting from different zones of the Puchuncaví Valley (Chile). CHEMOSPHERE 2014; 111:513-521. [PMID: 24997960 DOI: 10.1016/j.chemosphere.2014.03.127] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/12/2014] [Accepted: 03/24/2014] [Indexed: 06/03/2023]
Abstract
Metal contents in soil samples are commonly used to evaluate contamination levels. However, the distribution of metals is dependent on particle size. We investigated the distribution of metals in various particle size fractions of the soil from four sites of the Puchuncaví Valley (Central Chile). The soil samples were segregated into size fractions ranging from 0.3 to 20μm and analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of the statistical analysis of the total metal concentrations indicated that the soil samples from Greda and Maitenes, the sites nearest the industrial sources, are the most contaminated. For these sites, the size-fractionated samples containing higher concentrations of Cu, Zn, As, and Pb were found in the finer fractions, suggesting anthropogenic depositions from smelter facilities. In addition, a high Ca concentration was observed in the finer fractions, which could be attributed to the technological approaches used to reduce the SO2 emissions from the roasting process of copper sulfide. The mineral composition of fine particles permitted the identification of Tenorite and Calcium oxide, which are most likely associated with smelting activities, confirming emission of enriched particulate matter from the copper smelter.
Collapse
|
32
|
A preliminary comparison of three dermal exposure sampling methods: rinses, wipes and cotton gloves. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2014; 16:141-147. [PMID: 24281007 DOI: 10.1039/c3em00511a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Several methods exist to estimate dermal exposure and it is unclear how comparable they are. These methods fall into three main categories: (i) removal techniques (such as wiping or rinsing); (ii) interception techniques (such as gloves, patches, or coveralls); and (iii) fluorescent tracer techniques. Controlled experiments were conducted to compare two removal methods for exposure to particulate, and a removal method with an interception method for exposure to liquids. Volunteers' hands were exposed to three liquid solutions (glycerol-water solutions of different concentrations) and three particulates (Epsom salts, calcium acetate and zinc oxide) in simulated exposure scenarios. Both hands were exposed and a different sampling method was used on each to allow comparison of methods. Cotton glove samplers and a cotton wipe sampling method were compared for exposure to liquids. For exposure to powders a cotton wipe sampling method was compared to rinsing the hands in deionised water. Wipe and rinse methods generally yielded similar results for Epsom salts and zinc oxide (geometric mean [GM] ratios of wipe-to-rinse measurements of 0.6 and 1.4, respectively) but they did not for calcium acetate (GM wipe-to-rinse ratio of 4.6). For glycerol solutions measurements from the glove samplers were consistently higher than wipe samples. At lower levels of exposure the relative difference between the two methods was greater than at higher levels. At a hand loading level of 24,000 μg cm(-2) (as measured by wiping) the glove-to-wipe ratio was 1.4 and at a hand loading of 0.09 μg cm(-2) the ratio was 42.0. Wipe and rinse methods may be directly comparable but the relationship between glove and wipe sampling methods appears to be complex. Further research is necessary to enable conversion of exposure measurements from one metric to another, so as to facilitate more reliable risk assessment.
Collapse
|
33
|
A multi-spectroscopic approach to the characterization of early glaze opacifiers: Studies on an Achaemenid glazed brick found at Susa, south-western Iran (mid-first millennium BC). SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 116:49-56. [PMID: 23906671 DOI: 10.1016/j.saa.2013.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 06/26/2013] [Accepted: 07/01/2013] [Indexed: 06/02/2023]
Abstract
This paper presents the results of micro-Raman spectroscopy, energy dispersive X-ray fluorescence (XRF), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) studies performed on an Achaemenid glazed brick found at Susa (mid-first millennium BC). The results showed that calcium antimonate (CaSb2O6) and lead antimonate (Pb2Sb2O7) were used as white and yellow opacifiers in the white and orange glazes respectively. Moreover, the mixture of calcium antimonate and lead antimonate were used as opacifier in the green glaze. In addition, green, turquoise, blue, and orange colors were achieved by the dissolution of copper, cobalt, and iron-bearing materials in an alkali glaze. A black glazed line, whose color was obtained by copper and iron oxides, was used to separate the colored glazes. The present paper strongly suggests invasive micro-Raman spectroscopy for the identification of the opacifiers used in the early vitreous materials.
Collapse
|
34
|
Composition, production and procurement of glass at San Vincenzo Al Volturno: an early Medieval monastic complex in Southern Italy. PLoS One 2013; 8:e76479. [PMID: 24146876 PMCID: PMC3797782 DOI: 10.1371/journal.pone.0076479] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/20/2013] [Indexed: 11/18/2022] Open
Abstract
136 glasses from the ninth-century monastery of San Vincenzo and its workshops have been analysed by electron microprobe in order to situate the assemblage within the first millennium CE glass making tradition. The majority of the glass compositions can be paralleled by Roman glass from the first to third centuries, with very few samples consistent with later compositional groups. Colours for trailed decoration on vessels, for vessel bodies and for sheet glass for windows were largely produced by melting the glass tesserae from old Roman mosaics. Some weakly-coloured transparent glass was obtained by re-melting Roman window glass, while some was produced by melting and mixing of tesserae, excluding the strongly coloured cobalt blues. Our data suggest that to feed the needs of the glass workshop, the bulk of the glass was removed as tesserae and windows from a large Roman building. This is consistent with a historical account according to which the granite columns of the monastic church were spolia from a Roman temple in the region. The purported shortage of natron from Egypt does not appear to explain the dependency of San Vincenzo on old Roman glass. Rather, the absence of contemporary primary glass may reflect the downturn in long-distance trade in the later first millennium C.E., and the role of patronage in the "ritual economy" founded upon donations and gift-giving of the time.
Collapse
|
35
|
Importance of inoculum properties on the structure and growth of bacterial communities during Recolonisation of humus soil with different pH. MICROBIAL ECOLOGY 2013; 66:416-426. [PMID: 23512353 DOI: 10.1007/s00248-013-0208-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 03/04/2013] [Indexed: 06/01/2023]
Abstract
The relationship between community structure and growth and pH tolerance of a soil bacterial community was studied after liming in a reciprocal inoculum study. An unlimed (UL) humus soil with a pH of 4.0 was fumigated with chloroform for 4 h, after which < 1 % of the initial bacterial activity remained. Half of the fumigated soil was experimentally limed (EL) to a pH of 7.6. Both the UL and the EL soil were then reciprocally inoculated with UL soil or field limed (FL) soil with a pH of 6.2. The FL soil was from a 15-year-old experiment. The structural changes were measured on both bacteria in soil and on bacteria able to grow on agar plates using phospholipids fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analysis. The developing community pH tolerance and bacterial growth were also monitored over time using thymidine incorporation. The inoculum source had a significant impact on both growth and pH tolerance of the bacterial community in the EL soil. These differences between the EL soil inoculated with UL soil and FL soil were correlated to structural changes, as evidenced by both PLFA and DGGE analyses on the soil. Similar correlations were seen to the fraction of the community growing on agar plates. There were, however, no differences between the soil bacterial communities in the unlimed soils with different inocula. This study showed the connection between the development of function (growth), community properties (pH tolerance) and the structure of the bacterial community. It also highlighted the importance of both the initial properties of the community and the selection pressure after environmental changes in shaping the resulting microbial community.
Collapse
|
36
|
Physiologic conditions affect toxicity of ingested industrial fluoride. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2013; 2013:439490. [PMID: 23840230 PMCID: PMC3690253 DOI: 10.1155/2013/439490] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 03/13/2013] [Accepted: 04/03/2013] [Indexed: 11/29/2022]
Abstract
The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings.
Collapse
|
37
|
Arsenic mobility controlled by solid calcium arsenates: a case study in Mexico showcasing a potentially widespread environmental problem. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2013; 176:114-122. [PMID: 23416746 DOI: 10.1016/j.envpol.2012.12.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 06/01/2023]
Abstract
An As-contaminated perched aquifer under an urban area affected by mining was studied over a year to determine the contamination source species and the mechanism of As mobilization. Results show that the dissolution of calcium arsenates in residues disposed on an inactive smelter has caused high levels of As pollution in the adjoining downgradient 6-km perched aquifer, reaching up to 158 mg/L of dissolved As, and releasing a total of ca. 7.5 tons of As in a year. Furthermore, free calcium ion availability was found to control As mobility in the aquifer through the diagenetic precipitation of calcium arsenates (Ca5H2(AsO4)4·cH2O) preventing further mobilization of As. Results shown here represent a model for understanding a highly underreported mechanism of retention of arsenate species likely to dominate in calcium-rich environments, such as those in calcareous sediments and soils, where the commonly reported mechanism of adsorption to iron(III) oxyhydroxides is not the dominant process.
Collapse
|
38
|
[Research on the quantitative determination of lime in wheat flour by near-infrared spectroscopy]. GUANG PU XUE YU GUANG PU FEN XI = GUANG PU 2013; 33:69-73. [PMID: 23586227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The safety of wheat flour is always focused by all quarters of society. Based on comparing the feature of NIR spectra of calcium oxide, calcium hydroxide and calcium carbonate in this research, the diffuse reflection NIR spectra of the wheat flour samples with different content of calcium oxide, calcium hydroxide and calcium carbonate mixed in were collected. The calibration models of lime and calcium carbonate were developed by partial least square algorithm, with the validation method of cross validation. The result indicated that the determination coefficients (R2) of lime and calcium carbonate are 99.80% and 96.98% respectively, the root mean square errors of calibration set are 0.19 and 0.34 respectively; the root mean square errors of cross validation set are 0.26 and 0.75 respectively; the root mean square errors of prediction set are 0.63 and 0.44 respectively; the ratio performance deviations (RPD) are 8.57 and 5.24 respectively, which indicated that the calibration models were precise enough to adapt to the on-site rapid determination of lime in wheat flour. The result of F-test indicated that a very remarkable correlation exists between the estimated and specified values of the calibration sets and the external validation sets. This research, to some extent, will provide some reference methods for the rapid determination of wheat flour for quality safety, which is important for the quality control of wheat flour.
Collapse
|
39
|
Effect of incinerator bottom-ash composition on the mechanical behavior of backfill material. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2012; 113:377-382. [PMID: 23084273 DOI: 10.1016/j.jenvman.2012.09.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/28/2012] [Accepted: 09/14/2012] [Indexed: 06/01/2023]
Abstract
This study explores the influence of the chemical composition (SiO(2), CaO, Fe(2)O(3), and Al(2)O(3)) of incinerator bottom ash on its friction angle. Direct shear tests were performed to measure the strength of bottom ash with two distinctly different compositions. Then, an empirical equation was regressed to determine the correlation between each composition and the friction angle. The experimental results showed that the main constituent material of the incinerator bottom ash from general municipal wastes is SiO(2), and the friction angle is 48.04°-52.66°. The bottom ash from incineration plants treating both municipal wastes and general industrial wastes has a high content of iron-aluminum oxides, and its friction angle is 44.60°-52.52°. According to the multivariate regression analysis result, the friction angle of bottom ash of any composition is influenced mainly by the Fe(2)O(3) and Al(2)O(3) contents. This study used the friction angle of the bottom ash from four different incineration plants to validate the empirical equation, and found that the error between actual friction angles and the predicted values was -1.36% to 5.34%. Therefore, the regressed empirical equation in this study can be employed in engineering applications to preliminarily identify the backfill quality of incinerator bottom ash.
Collapse
|
40
|
An inventory of trace elements inputs to French agricultural soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 439:87-95. [PMID: 23063913 DOI: 10.1016/j.scitotenv.2012.09.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/07/2012] [Accepted: 09/08/2012] [Indexed: 06/01/2023]
Abstract
The inputs of ten trace elements (As, Cd, Cu, Cr, Hg, Mo, Ni, Pb, Se, Zn) to French agricultural soils have been assessed. The six main sources considered were: pesticides, mineral fertilizers, animal manure, liming materials, sludge and composts and atmospheric deposition. Data were collected to compute inputs at both national and regional (departmental) scales. The inventory methodology is based on two principles: data are traceable and easy to update. At a national scale, the inventory showed that trace elements inputs can be ranked: Zn≫Cu≫Cr>Pb>Ni>As=Mo>Se>Cd>Hg. Animal manure, mineral fertilizers and pesticides are the predominant sources of TEs. These results are globally in agreement with literature data though atmospheric deposition is shown to be lower than in more industrial countries such as China and United Kingdom where similar surveys were conducted. The inputs of trace elements vary strongly between regions in relation with agricultural activities. This inventory (and the related database) provides basis for developing and monitoring policies to control and reduce trace elements contamination of agricultural soils at both national and regional (departmental) scales.
Collapse
|
41
|
[Identification study of raw oyster and calcined ostreae concha]. ZHONG YAO CAI = ZHONGYAOCAI = JOURNAL OF CHINESE MEDICINAL MATERIALS 2012; 35:1590-1594. [PMID: 23627121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
OBJECTIVE To identify the differences in characteristics of raw oyster and oysters calcined under different temperatures. METHODS Identified raw oyster, oysters calcined under different temperatures and calcium carbonate, calcium oxide by differential thermal analysis, infrared spectroscopy and X-ray diffraction analysis. RESULTS Composition of calcined oysters was closer to calcium carbonate than raw oyster. CONCLUSION The fingerprints are established and identify raw oyster and calcined oysters.
Collapse
|
42
|
[Compositional characteristics and roles of soil mineral substances in depressions between hills in karst region]. YING YONG SHENG TAI XUE BAO = THE JOURNAL OF APPLIED ECOLOGY 2012; 23:685-693. [PMID: 22720612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Based on the investigation and analysis of seven soil mineral substance variables, nine vegetation factors, four topographical factors, and ten soil physicochemical factors in the 200 m x 40 m dynamic monitoring plots in farmland, forest plantation, secondary forest, and primary forest in the depressions between hills in karst region, and by using traditional statistical analysis, principal component analysis (PCA), and canonical correlation analysis (CCA), this paper studied the compositional characteristics and roles of soil mineral substances as well as the coupling relationships between the mineral substances and the vegetation, topography, and other soil properties. In the depressions, soil mineral substances were mainly composed of SiO2, Al2O3, K2O, and Fe2O3, whose contents were obviously lower than the mean background values of the soils in the world and in the zonal red soils at the same latitudes. The soil CaO and MgO contents were at medium level, while the soil MnO content was very low. The composition of soil mineral substances and their variation degrees varied with the ecosystems, and the soil development degree also varied. There was a positive correlation between vegetation origin and soil origin, suggesting the potential risk of rock desertification. Due to the high landscape heterogeneity of the four ecosystems, PCA didn't show good effect in lowering dimension. In all of the four ecosystems, soil mineral substances were the main affecting factors, and had very close relationships with vegetation, topography, and other soil properties. Especially for SiO2, CaO, and MnO, they mainly affected the vegetation species diversity and the soil organic matter, total nitrogen, and total potassium. This study indicated that soil mineral substances were the one of the factors limiting the soil fertility and vegetation growth in the depressions between hills in karst region. To effectively use the soil mineral resources and rationally apply mineral nutrients would have significances in the restoration and reconstruction of karst degraded ecosystems.
Collapse
|
43
|
Matrix effects in the energy dispersive X-ray analysis of CaO-Al(2)O(3)-MgO inclusions in steel. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2011; 17:963-971. [PMID: 22051086 DOI: 10.1017/s1431927611012268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Energy dispersive X-ray microanalysis of micron-sized inclusions in steel is of considerable industrial importance. Measured spectra and Monte Carlo simulations show a significant effect of the steel matrix on analysis of CaO-Al(2)O(3)-MgO inclusions: the steel matrix filters the softer (Al and Mg) characteristic X-rays, increasing the relative height of the Ca peak. Bulk matrix correction methods would not result in correct inclusion compositions, but operating at a lower acceleration voltage shifts the effect to smaller inclusion sizes.
Collapse
|
44
|
Photosynthesis is improved by exogenous calcium in heat-stressed tobacco plants. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:2063-71. [PMID: 21803445 DOI: 10.1016/j.jplph.2011.06.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 06/15/2011] [Accepted: 06/20/2011] [Indexed: 05/19/2023]
Abstract
Effects of exogenous calcium chloride (CaCl(2)) (20 mM) on photosynthetic gas exchange, photosystem II photochemistry, and the activities of antioxidant enzymes in tobacco plants under high temperature stress (43°C for 2 h) were investigated. Heat stress resulted in a decrease in net photosynthetic rate (P(n)), stomatal conductance as well as the apparent quantum yield (AQY) and carboxylation efficiency (CE) of photosynthesis. Heat stress also caused a decrease of the maximal photochemical efficiency of primary photochemistry (F(v)/F(m)). On the other hand, CaCl(2) application improved P(n), AQY, and CE as well as F(v)/F(m) under high temperature stress. Heat stress reduced the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), whereas the activities of these enzymes either decreased less or increased in plants pretreated with CaCl(2); glutathione reductase (GR) activity increased under high temperature, and it increased more in plants pretreated with CaCl(2). There was an obvious accumulation of H(2)O(2) and O(2)(-) under high temperature, but CaCl(2) application decreased the contents of H(2)O(2) and O(2)(-) under heat stress conditions. Heat stress induced the level of heat shock protein 70 (HSP70), while CaCl(2) pretreatment enhanced it. These results suggested that photosynthesis was improved by CaCl(2) application in heat-stressed plants and such an improvement was associated with an improvement in stomatal conductance and the thermostability of oxygen-evolving complex (OEC), which might be due to less accumulation of reactive oxygen species.
Collapse
|
45
|
Remote-Raman spectroscopic study of minerals under supercritical CO2 relevant to Venus exploration. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 80:75-81. [PMID: 21333587 DOI: 10.1016/j.saa.2011.01.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 01/17/2011] [Accepted: 01/23/2011] [Indexed: 05/30/2023]
Abstract
The authors have utilized a recently developed compact Raman spectrometer equipped with an 85 mm focal length (f/1.8) Nikon camera lens and a custom mini-ICCD detector at the University of Hawaii for measuring remote Raman spectra of minerals under supercritical CO(2) (Venus chamber, ∼102 atm pressure and 423 K) excited with a pulsed 532 nm laser beam of 6 mJ/pulse and 10 Hz. These experiments demonstrate that by focusing a frequency-doubled 532 nm Nd:YAG pulsed laser beam with a 10× beam expander to a 1mm spot on minerals located at 2m inside a Venus chamber, it is possible to measure the remote Raman spectra of anhydrous sulfates, carbonates, and silicate minerals relevant to Venus exploration during daytime or nighttime with 10s integration time. The remote Raman spectra of gypsum, anhydrite, barite, dolomite and siderite contain fingerprint Raman lines along with the Fermi resonance doublet of CO(2). Raman spectra of gypsum revealed dehydration of the mineral with time under supercritical CO(2) at 423 K. Fingerprint Raman lines of olivine, diopside, wollastonite and α-quartz can easily be identified in the spectra of these respective minerals under supercritical CO(2). The results of the present study show that time-resolved remote Raman spectroscopy with a compact Raman spectrometer of moderate resolution equipped with a gated intensified CCD detector and low power laser source could be a potential tool for exploring Venus surface mineralogy both during daytime and nighttime from a lander.
Collapse
|
46
|
Assessment of oral bioaccessibility of arsenic in playground soil in Madrid (Spain): a three-method comparison and implications for risk assessment. CHEMOSPHERE 2011; 84:1386-1391. [PMID: 21601908 DOI: 10.1016/j.chemosphere.2011.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 04/23/2011] [Accepted: 05/01/2011] [Indexed: 05/30/2023]
Abstract
Three methodologies to assess As bioaccessibility were evaluated using playground soil collected from 16 playgrounds in Madrid, Spain: two (Simplified Bioaccessibility Extraction Test: SBET, and hydrochloric acid-extraction: HCl) assess gastric-only bioaccessibility and the third (Physiologically Based Extraction Test: PBET) evaluates mouth-gastric-intestinal bioaccessibility. Aqua regia-extractable (pseudo total) As contents, which are routinely employed in risk assessments, were used as the reference to establish the following percentages of bioaccessibility: SBET-63.1; HCl-51.8; PBET-41.6, the highest values associated with the gastric-only extractions. For Madrid playground soils--characterised by a very uniform, weakly alkaline pH, and low Fe oxide and organic matter contents--the statistical analysis of the results indicates that, in contrast with other studies, the highest percentage of As in the samples was bound to carbonates and/or present as calcium arsenate. As opposed to the As bound to Fe oxides, this As is readily released in the gastric environment as the carbonate matrix is decomposed and calcium arsenate is dissolved, but some of it is subsequently sequestered in unavailable forms as the pH is raised to 5.5 to mimic intestinal conditions. The HCl extraction can be used as a simple and reliable (i.e. low residual standard error) proxy for the more expensive, time consuming, and error-prone PBET methodology. The HCl method would essentially halve the estimate of carcinogenic risk for children playing in Madrid playground soils, providing a more representative value of associated risk than the pseudo-total concentrations used at present.
Collapse
|
47
|
Mechanical and leaching behaviour of slag-cement and lime-activated slag stabilised/solidified contaminated soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2011; 409:2325-2335. [PMID: 21420148 DOI: 10.1016/j.scitotenv.2011.02.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 02/19/2011] [Accepted: 02/24/2011] [Indexed: 05/30/2023]
Abstract
Stabilisation/solidification (S/S) is an effective technique for reducing the leachability of contaminants in soils. Very few studies have investigated the use of ground granulated blast furnace slag (GGBS) for S/S treatment of contaminated soils, although it has been shown to be effective in ground improvement. This study sought to investigate the potential of GGBS activated by cement and lime for S/S treatment of a mixed contaminated soil. A sandy soil spiked with 3000mg/kg each of a cocktail of heavy metals (Cd, Ni, Zn, Cu and Pb) and 10,000mg/kg of diesel was treated with binder blends of one part hydrated lime to four parts GGBS (lime-slag), and one part cement to nine parts GGBS (slag-cement). Three binder dosages, 5, 10 and 20% (m/m) were used and contaminated soil-cement samples were compacted to their optimum water contents. The effectiveness of the treatment was assessed using unconfined compressive strength (UCS), permeability and acid neutralisation capacity (ANC) tests with determination of contaminant leachability at the different acid additions. UCS values of up to 800kPa were recorded at 28days. The lowest coefficient of permeability recorded was 5×10(-9)m/s. With up to 20% binder dosage, the leachability of the contaminants was reduced to meet relevant environmental quality standards and landfill waste acceptance criteria. The pH-dependent leachability of the metals decreased over time. The results show that GGBS activated by cement and lime would be effective in reducing the leachability of contaminants in contaminated soils.
Collapse
|
48
|
Effect of soil acidification induced by a tea plantation on chemical and mineralogical properties of Alfisols in eastern China. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2011; 33:137-148. [PMID: 20563880 DOI: 10.1007/s10653-010-9327-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 06/11/2010] [Indexed: 05/29/2023]
Abstract
The effect of a tea plantation on soil basic properties, chemical and mineralogical compositions, and magnetic properties of Alfisols from eastern China was studied. Under the tea plantation, acidification took place within a soil depth of 70 cm, with the maximum difference in pH in the upper 17 cm (ΔpH = 2.80). Both the tea plantation and unused soil profiles were predominated by free Fe and Al oxides, i.e. citrate/bicarbonate/dithionite extractable Fe (Fe(d)) and Al (Al(d)). Tea plantation soil was characterized by higher Al(d) and Fe(d) and lower Fe oxalate, Fe(2)O(3) and Al(2)O(3); CaO was depleted, whereas SiO(2) accumulated. Acidification induced by the tea plantation led to destruction of vermiculite followed by dissolution of the hydroxy-Al interlayers within its structure. The data clearly demonstrated that significant soil weathering occurred with acidification caused by tea cultivation. This acidification also resulted in decreased content of ferrimagnetic minerals due to the dissolution of minerals and movement of Fe in the profile.
Collapse
|
49
|
Sandstones of unexpectedly high diffusibility. JOURNAL OF CONTAMINANT HYDROLOGY 2011; 122:40-52. [PMID: 21146250 DOI: 10.1016/j.jconhyd.2010.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 07/23/2010] [Accepted: 11/01/2010] [Indexed: 05/30/2023]
Abstract
Measurements have been made of diffusion coefficients (D(i)=-mass flux/concentration gradient) using a double reservoir, steady-state method with two tracers, CaBr(2) and amino-G-acid, on intact samples of Triassic red-bed sandstone from northwest England. Diffusibility (D'=D(i)/diffusion coefficient in water) averages 0.124, ranging between 0.075 and 0.215 (porosity 0.1 to 0.24), very similar for the two tracers. Implied tortuosities (actual path length/straight line length) average 1.21 (range 1.06 to 1.47), with constrictivities close to 1. In comparison with limited red-bed sandstone data from elsewhere, these D' values are up to 4 times greater, and tortuosity correspondingly lower. Re-interpretation of formation factor data from previous studies on shallow sandstone samples also from northwest England confirms that diffusibility is significantly higher in these sandstones than others from similar palaeoenvironment/stratigraphic units. The lower tortuosities appear to result from the relatively high permeability, open fabric of the rock, properties likely to be present in shallow sandstone systems used for water supply. It is concluded that diffusion rates may, in some shallow freshwater-containing continental sandstone systems, be significantly greater than is implied by estimates of sandstone diffusibility current in the literature.
Collapse
|
50
|
Efficacy of lime, biosolids, and mycorrhiza for the phytostabilization of sulfidic copper tailings in Chile: a greenhouse experiment. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2011; 13:107-25. [PMID: 21598780 DOI: 10.1080/15226510903535056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Inadequate abandonment of copper mine tailings under semiarid Mediterranean climate type conditions has posed important environmental risks in Chile due to wind and rain erosion. There are cost-effective technologies for tailings stabilization such as phytostabilization. However, this technology has not been used in Chile yet. This study evaluated in a greenhouse assay the efficacy of biosolids, lime, and a commercial mycorrhiza to improve adverse conditions of oxidized Cu mine tailings for adequate establishment and grow of Lolium perenne L. var nui. Chemical characterization of experimental substrates and pore water samples were performed; plant density, biomass production, chlorophyll content, and metal content in shoots was evaluated in rye grass plants after an eight-week growth period. Results showed that neutralization of tailings and superficial application of biosolids increased both aerial biomass production and chlorophyll content of rye grass. Increased Cu solubilization and translocation to shoots occurred after biosolids application (mixed), particularly on unlimed tailings, due to formation of soluble organometallic complexes with dissolved organic carbon (DOC) which can be readily absorbed by plant roots. Positive effects of mycorrhizal inoculation on rye grass growth were restricted to treatments with superficial application of biosolids, probably due to Cu toxicity effects on commercial mycorrhiza used (Glomulus intraradices).
Collapse
|