Depth profile of major and trace elements in estuarine core sediment using the EDXRF technique

How Does Adjacent Land Use Influence Sediment Metals Content and Potential Ecological Risk in the Hongze Lake Wetland?

Metal pollution in lake wetlands has become increasingly serious in China and worldwide due to the rapid growth of urbanization and agricultural activities. However, comprehensive assessments of metal pollution in lake wetland sediments that are associated with land use change have been limited from an international perspective. Metal concentrations (As, Cd, Cr, Cu, Hg, Mn, Pb, and Zn) were measured in the surface soils and surrounding sediments of five land use types in the eastern Hongze Lake wetlands, including Farmland (FL), Culture Ponds (CP), Reed Land (RL), Poplar Forests (PF), and Willow Forests (WF). The metal pollution status was assessed using the geo-accumulation index and the potential ecological risk index; The results showed that the average concentrations of As, Cd, Mn, and Zn in the surface soils and As, Cd, Cu, and Zn in the sediments, exceeded the background values of Jiangsu Province, China. The FL soils and surrounding sediments were moderately contaminated with As, whereas the sediments surrounding the CP were uncontaminated to moderately contaminated with Cd. Metal pollution in both soils and sediments was greater on farmland than on other types of land use. Furthermore, there were significant positive correlations between the values of the soil risk index and the values of the surrounding sediment risk index. Correlation analysis (CA) and principal component analysis (PCA) found that metals may be derived from agricultural activities such as the application of chemical and organic fertilizers, as well as domestic sewage, industrial wastewater, and geological anomalies. These findings shed new light on the quantitative impacts of adjacent land use practices on sediment metal pollution and provide a scientific foundation for wetland management decision-making.

Environmental Assessment of Potentially Toxic Elements Using Pollution Indices and Data-Driven Modeling in Surface Sediment of the Littoral Shelf of the Mediterranean Sea Coast and Gamasa Estuary, Egypt

Coastal environmental assessment techniques have evolved into one of the most important fields for the long-term development and management of coastal zones. So, the overall aim of the present investigation was to provide effective approaches for making informed decisions about the Gamasa coast sediment quality. Over a two-year investigation, sediment samples were meticulously collected from the Gamasa estuary and littoral shelf. The inductively coupled plasma mass spectra (ICP-MS) was used to the total concentrations of Al, Fe, Ti, Mg, Mn, Cu, P, V, Ba, Cr, Sr, Co, Ni, Zn, Pb, Zr, and Ce. Single elements environmental pollution indices including the geoaccumulation index (Igeo), contamination factor (CF), and enrichment factor (EF), as well as multi-elements pollution indices comprising the potential ecological risk index (RI), degree of contamination (Dc), and pollution load index (PLI) were used to assess the sediment and the various geo-environmental variables affecting the Mediterranean coastal system. Furthermore, the Dc, PLI, and RI were estimated using the random forest (RF) and Back-Propagation Neural Network (BPNN) depending on the selected elements. According to the Dc results, all the investigated sediment samples categories were considerably contaminated. Cr, Co, Ni, Cu, Zr, V, Zn, P, and Mn showed remarkable enrichment in sediment samples and were originated from anthropogenic sources based on the CF, EF, and Igeo data. Moreover, the RI findings revealed that all the samples tested pose a low ecologically risk. Meanwhile, based on PLI, 70% of the Gamasa estuary samples were polluted, while 93.75% of littoral shelf sediment was unpolluted. The BPNNs -PCs-CD-17 model performed the best and demonstrated a better association between exceptional qualities and CD. With R2 values of 1.00 for calibration (Cal.) and 1.00 for validation (Val.). The BPNNs -PCs-PLI-17 models performed the best in terms of measuring PLI with respective R2 values of 1.00 and 0.98 for the Cal. and Val. datasets. The findings showed that the RF and BPNN models may be used to precisely quantify the pollution indices (Dc, PLI, and RI) in calibration (Cal.) and validation (Val.) datasets utilizing potentially toxic elements of surface sediment.

Elemental analysis of residual ash generated during plasma incineration of cellulosic, rubber and plastic waste

Management of plastic, rubber and cellulosic waste from various industries is a challenging task. An engineering scale plasma pyrolysis based incinerator has been commissioned for incineration of combustible waste, including plastic, rubber and cellulose. Operational trials of wastes with simulated composition show a weight reduction factor of more than 18 and volume reduction factor of more than 30. The volume reduction factor is tenfold higher than the compaction process currently practised for rubber and plastic wastes. Representative residual ash samples derived from these runs are subjected to their elemental analysis using EDXRF technique and results are comparable with the published literature. Relative variation of individual elements is attributed to the type of waste and feed composition. Analysis is aided with the calculation of index of geoaccumulation, enrichment factor (EF), contamination factor (CF) and pollution load index (PLI). From this study, it is evident that S, Cr, Zn, As, Se, Hg and Pb are of concern for environment in residual ash from plasma incineration of combustible waste. The efficacy of the incineration process is evaluated; C, H and O reduction achieved is more than 98% and overall enrichment ratio (ER) for the inorganic elements is more than 4.5. This study highlights the importance of elemental composition for the performance analysis of the plasma based incineration as well as hazards evaluation of constituents in residual ash for its further management.

Ecological Risk from Toxic Metals in Sediments of the Yangtze, Yellow, Pearl, and Liaohe Rivers, China

In this study, the concentrations of six toxic metals (Cd, Cr, Cu, Ni, Pb, and Zn) in surface sediments within the Yangtze, Yellow, Pearl, and Liaohe rivers, China, were analyzed, and their associated pollution statuses and potential ecological risks were assessed using the geoaccumulation index (I_geo), sediment quality guidelines (SQGs), and the potential ecological risk index (RI). Relatively high toxic metal concentrations were observed in the Pearl and Yangtze rivers, whereas relatively low concentrations were observed in the Yellow and Liaohe rivers. In the Yangtze, Pearl, and Liaohe rivers, the concentrations of these six toxic metals were higher than their background values. Based on the SQGs, the concentrations of Cd, Cr, and Cu in the four rivers were found to be higher than the threshold effect levels (TELs) but lower than the probable effect levels (PELs); however, the concentration of Ni exceeded the PEL in the Pearl River sediments. The I_geo index indicated that all four rivers were heavily contaminated with Cd. The RI of the Pearl and Yellow rivers was classed as high and low, respectively, and that of the Yangtze and Liaohe rivers as moderate. The pollution status of the sediments in the four major rivers was explored in relation to the geochemical background, the ecological toxicity of metals, and the sensitivity of the local benthic communities. These results provide meaningful information for directing river management priorities.

The environmental quality of sediments of rivers near prospection areas of semiprecious rocks

Mineral exploration areas are recognized for negatively affecting site environmental quality. The recent contaminations in the cities of Brumadinho, Mariana, Santo Antônio do Grama (Minas Gerais), and Barcarena (Pará) point to the seriousness of this issue in Brazil. However, studies on the influence of mining tailings from the extraction of semiprecious rocks on the quality of the sediments of water systems are rare. The aim of this study is to evaluate the influence of mining activities (amethyst, quartz, agate, calcite, and gypsum) on the quality of the sediments of Rio de Várzea, southern Brazil, the biggest region of amethyst rock extraction in the world. The concentrations of the chemical species Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, Fe₂O₃, Cr, Mn, Co, Cu, Zn, Zr, Ba, Cd, and Pb were determined by the technique energy-dispersive X-ray emission spectrometry (EDXRF). In the study, moderate contamination of the sediments of the Várzea River was demonstrated by means of background strategies (contamination factor, enrichment factor, and geoaccumulation index). Statistical analysis with the use of ANOVA, Tukey test, and principal component analysis revealed significant differences of concentrations of the chemical species of the sediments at the exit of the mining zone in relation to the other study areas.

Wavelength dispersive X-ray fluorescence determination of major oxides in bottom and peat sediments for paleoclimatic studies

The wavelength dispersive X-ray fluorescence method was applied to identify the distribution of major oxides within bottom and peat sediments containing organic matter of up to 70 wt.%. Samples were prepared as glass beads by fusing with lithium metaborate. The accuracy of results was assessed by flame photometry, spectrophotometry, and flame atomic absorption techniques. The proposed technique requires a sample weighing only 110 mg, which allows to analyze each centimeter of core collected at high-mountainous sites with undisturbed environment and eventually achieve uniquely high resolution of paleoclimatic reconstructions of global and regional climatic and environmental changes.

The current status of heavy metal in lake sediments from China: Pollution and ecological risk assessment

Heavy metal contamination in lake sediments is a serious problem, particularly in developing countries such as China. To evaluate heavy metal pollution and risk of contamination in lake sediments on a national scale in China, we collated available data in the literature of the last 10 years on lake sediments polluted with heavy metals from 24 provinces in China. Based on these data, we used sediment quality guidelines, geoaccumulation index, and potential ecological risk index to assess potential ecological risk levels. The results showed that approximately 20.6% of the lakes studied exceeded grade II level in Chinese soil quality standards for As, 31.3% for Cd, 4.6% for Cu, 20.8% for Ni, 2.8% for Zn, and 11.1% for Hg, respectively. Besides, the mean concentrations for As in 10.3% of lakes, Hg in 11.9% of lakes, and Ni in 31.3% of lakes surpassed the probable effect level. The potential ecological risk for toxic metals decreased in the order of Cd > Hg > As > Cu > Pb > Ni > Cr > Zn, and there were 21.8% of the lakes studied in the state of moderate risk, 10.9% in high risk, and 12.7% in very high risk. It can be concluded that Chinese lake sediments are polluted by heavy metals to varying degrees. In order to provide key management targets for relevant administrative agencies, based on the results of the pollution and ecological risk assessments, Cd, Hg, As, Cu, and Ni were selected as the priority control heavy metals, and the eastern coastal provinces and Hunan province were selected as the priority control provinces. This article, therefore, provides a comprehensive assessment of heavy metal pollution in lake sediments in China, while providing a reference for the development of lake sediment quality standards.

Distribution of PAHs in different compartment of creek ecosystem: Ecotoxicological concern and human health risk

We report levels of polycyclic aromatic hydrocarbons in sediment, seawater, fish and crab samples from Thane creek, India. Concentrations of sixteen USEPA PAH in sediments varies from 874 to 1925ngg^-1, dry weight (dw) in winter, between 219-495ngg^-1 in summer. In seawater Σ₁₆ PAHs concentration during winter was recorded 706±193ngL^-1, and during summer 337±79ngL^-1. Total concentrations of PAHs in consumable portion of lizard fish, bombay duck and crab were found 156.8±18 and 122±24.5ngg^-1, 117.4±17.65ngg^-1 and 95.8±16.2ngg^-1, 348±94.5 and 95.62±31.9ngg^-1 wet weight (ww) in summer and winter respectively. PAHs concentration were compared with sediments quality guidelines viz. ERL-ERM, TEL-PEL indexes for finding ecotoxicological risk on marine organism. The ILCR values were above public screening criteria for carcinogens.

Distribution and estrogenic potential of endocrine disrupting chemicals (EDCs) in estuarine sediments from Mumbai, India

Endocrine disrupting chemicals (EDCs) are responsible for inappropriate development and they alter the hormonal and homeostatic systems of organism. Phthalates (PAEs), bisphenol A (BPA) and other EDCs were monitored in surface sediments at different stations across Thane Creek, India. Analysis of PAEs was carried out using GC-MS technique, while BPA and other EDCs were analyzing on UPLC-PDA instrument. Di-n-butyl phthalate (DBP) had the highest concentration among all fourteen analyzed phthalates ranges between 0.13 and 0.4 mg kg(-1); and was detectable in all sediment samples. Strong correlation (r = 0.95, p < 0.01) was observed between total organic carbon (TOC, %) and total PAEs. BPA was also detected in all samples; average BPA concentration varies from 16.3 to 35.79 μg kg(-1) with mean value 25.15 μg kg(-1) dry weight of sediment. Synthetic EDCs such as 4-para-nonylphenol (NP) and 4-tert-octylphenol (OP) were also analyzed; and their average concentrations were founds to be 356.5 and 176 μg kg(-1), respectively. Estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) were the main contributors to the overall estradiol equivalent concentration (EEQs) in sediment, their average total percentage contributions is more than 90 %.

Distribution and ecotoxicological concerns of persistent organic pollutants in sediment from creek ecosystem

In order to study the distribution and ecotoxicological concerns of persistent organic pollutants, grab sediment samples were collected from different locations across Thane creek, India. Analyses of samples were carried out using gas chromatography (GC)-electron capture detector and GC-mass spectrometry techniques. In organochlorine pesticides (OCPs), DDT (1,1,1,-trichloro-2,2-bis(p-chlorophenyl) ethane), DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene), DDD (1-chloro-4-(2,2-dichloro-1-(4-chlorophenyl)ethyl) benzene) and α, β, and γ conformer of hexachlorocyclohexane (HCH), and 9 polychlorinated biphenyls (PCBs) congeners were analyzed in surface sediment samples. Concentrations of these pollutants in grab sediment samples may indicate their current use and impact on marine ecosystem. Average concentrations of total DDT (including DDD and DDE), HCH, and Σ9PCBs were found to be 4.9, 12.5, and 2.9 µg kg(-1)(dry weight) respectively. High concentrations of OCPs and PCBs were found at discharge locations in creek compared to other locations. Location-wise distribution of OCPs and PCBs indicates their high concentrations at the waste water receiving point. Data were compared for ecotoxicological impacts based on the levels specified in the sediment quality standards of the US Environmental Protection Agency and the Canadian Council of Ministers of the Environment. γ-HCH was found to have maximum potential to induce ecotoxicological impacts.

Analytical approaches for determination of bromine in sediment core samples by X-ray fluorescence spectrometry

Bromine has been recognized as a valuable indicator for paleoclimatic studies. Wavelength dispersive X-ray fluorescence (WDXRF) and total reflection X-ray fluorescence (TXRF) methods were applied to study the bromine distributions in lake sediment cores. Conventional WDXRF technique usually requires relatively large mass of a sediment sample and a set of calibration samples. Some analytical approaches were developed to apply WDXRF to small sediment core samples in the absence of adequate calibration samples with a known Br content. The mass of a sample to be analyzed was reduced up to 200-300mg and the internal standard method with correction using fundamental parameters was developed for Br quantification. TXRF technique based on the direct analysis of a solid suspension using 20mg of sediment sample by internal standard method was additionally tested. The accuracy of the WDXRF and TXRF techniques was assessed by the comparative analysis of reference materials of sediments, soil and biological samples. In general, good agreement was achieved between the reference values and the measured values. The detection limits of Br were 1mg/kg and 0.4mg/kg for WDXRF and TXRF respectively. The results of the Br determination obtained with different XRF techniques were comparable to each other and used for paleoclimatic reconstructions.

Distribution and baseline values of trace elements in the sediment of Var River catchment, Southeast France

This study reports on the determination of trace element (TE)-Li, As, Co, Cs, Cu, Pb, U, and Zn-and major element (ME)-Si, Al, Fe, Mg, Ca, Mn, Na, and K-concentrations in 18 riverbed sediments and a sediment core from the Var River catchment using inductively coupled plasma mass spectrometry (ICP-MS). The results were compared with those of a reference sediment core, and the contribution of clay and organic carbon contents in the distribution of TE and ME in the sediment samples was investigated. The mean concentrations of the ME were comparable in both core and riverbed samples and were within the natural averages. In the case of TE, the concentrations were lower in riverbed sediment samples than those found in the sediment core. High mean concentration of As was observed (7.6 μg g(-1)) in both core and riverbed sediments, relatively higher than the worldwide reported values. The obtained data indicated that the natural high level of arsenic might be originated from the parent rocks, especially metamorphic rocks surrounding granites and from Permian sediments. Statistical approach, viz., Pearson correlation matrix, was applied to better understand the correlation among TE in both riverbed and sediment core samples. No significant metallic contamination was detected in the low Var valley despite of the localization of several industrial facilities. Therefore, results confirm that the concentrations of the TE obtained in the riverbed sediments could be considered as a baseline guide for future pollution monitoring program.