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Ma S, Geng H, Yan C, Han X, Xu D, Zhao F, Blake RE, Zhou B, Chen H, Yuan R, Jin B, Liu H, Wang F. Nutrient dynamics and microbial community response in macrophyte-dominated lakes: Implications for improved restoration strategies. J Environ Manage 2023; 325:116372. [PMID: 36252327 DOI: 10.1016/j.jenvman.2022.116372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/28/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Although lakes dominated by macrophytes are conducive to ecological balance, this balance is easily disrupted by excessive nutrients flowing into the lake. However, knowledge of whether excessive nutrients lead to different microbial environmental vulnerabilities in the lake sediment between macrophyte-dominated areas and macrophyte-free areas is a prerequisite for the implementation of targeted protection measures. In this study, we investigated bacterial communities in sediments using high-throughput sequencing of 16S rRNA genes. Our results showed that the sources of total nitrogen (TN) and organic matter (OM) were related to the macrophytes. The structure, drivers, and interspecific associations of bacterial community, which were more susceptible to increased changes in TN and OM, differed significantly between macrophyte-dominated areas and macrophyte-free areas. More precisely, the lake edge, where was occupied by macrophytes, had a higher proportion of deterministic phylogenetic turnover (88.89%) than other sites, as well as a wider ecological niche and a tighter network structure. Further, as the difference in TN increased, the main assembly processes in surface sediments changed from stochastic to deterministic. However, the majority of phyla from the lake edge showed a greater correlation with excessive nutrients, and the selection of the community by excessive nutrients was more obvious at the edge of the lake. In addition, our results demonstrated that the stability of the bacterial community in macrophyte-free areas is greater than in macrophyte-dominated areas, while an excessively high deterministic process ratio and nutrient (TN and OM) concentration significantly reduced bacterial community stability at macrophyte-dominated areas. Taken together, these results provide a better understanding of the effects of excessive nutrients derived from macrophytes on bacterial community patterns, and highlight the importance of avoiding the accumulation of TN and OM in macrophyte-dominated areas to enhance the sustainability of the ecosystem after restoration of lakes with macrophytes.
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Affiliation(s)
- Shuai Ma
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China; School of Environment, Beijing Normal University, No.19, Xinjiekouwai St, Haidian District, Beijing, 100875, PR China
| | - Huanhuan Geng
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Changchun Yan
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Xiaomin Han
- Shunyi District Water Authority, 3 Fuxing East Road, Shunyi District, Beijing, 101300, PR China
| | - Dan Xu
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Furong Zhao
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Ruth E Blake
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave, New Haven, CT 06511, USA
| | - Beihai Zhou
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Huilun Chen
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Rongfang Yuan
- School of Energy & Environmental Engineering, And Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083, PR China
| | - Baoshi Jin
- School of Resources and Environment, Anqing Normal University, 1318 Jixian North Road, Anqing, Anhui, 246133, PR China
| | - Haijun Liu
- School of Resources and Environment, Anqing Normal University, 1318 Jixian North Road, Anqing, Anhui, 246133, PR China.
| | - Fei Wang
- School of Environment, Beijing Normal University, No.19, Xinjiekouwai St, Haidian District, Beijing, 100875, PR China.
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Xia C, Geng H, Li X, Zhang Y, Wang F, Tang X, Blake RE, Li H, Chang SJ, Yu C. Mechanism of methylphosphonic acid photo-degradation based on phosphate oxygen isotopes and density functional theory. RSC Adv 2019; 9:31325-31332. [PMID: 35527942 PMCID: PMC9072446 DOI: 10.1039/c9ra05169d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/06/2019] [Indexed: 11/21/2022] Open
Abstract
Methylphosphonic acid (MPn) is an intermediate in the synthesis of the phosphorus-containing nerve agents, such as sarin and VX, and a biosynthesis product of marine microbes with ramifications to global climate change and eutrophication. Here, we applied the multi-labeled water isotope probing (MLWIP) approach to investigate the C-P bond cleavage mechanism of MPn under UV irradiation and density functional theory (DFT) to simulate the photo-oxidation reaction process involving reactive oxygen species (ROS). The results contrasted with those of the addition of the ROS-quenching compounds, 2-propanol and NaN3. The degradation kinetics results indicated that the extent of MPn degradation was more under alkaline conditions and that the degradation process was more rapid at the initial stage of the reaction. The phosphate oxygen isotope data confirmed that one exogenous oxygen atom was incorporated into the product orthophosphate (PO4) following the C-P bond cleavage, and the oxygen isotopic composition of this free PO4 was found to vary with pH. The combined results of the ROS-quenching experiments and DFT indicate that the C-P bond was cleaved by OH-/˙OH and not by other reactive oxygen species. Based on these results, we have established a mechanistic model for the photolysis of MPn, which provides new insights into the fate of MPn and other phosphonate/organophosphate compounds in the environment.
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Affiliation(s)
- Congcong Xia
- Jiangxi Transportation Institute China 809 Jinsha Road 330038 Nanchang China
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
| | - Huanhuan Geng
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
| | - Xiaobao Li
- Jiangxi Transportation Institute China 809 Jinsha Road 330038 Nanchang China
| | - Yiyue Zhang
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
| | - Fei Wang
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
| | - Xiaowen Tang
- School of Pharmaceutical Sciences, Sun Yet-sen University 510006 Guangzhou China
| | - R E Blake
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
- Department of Geology and Geophysics, Yale University P.O. Box 208109 New Haven CT 06520-8109 USA
| | - Hui Li
- Department of Geology and Geophysics, Yale University P.O. Box 208109 New Haven CT 06520-8109 USA
| | - Sae Jung Chang
- Department of Geology and Geophysics, Yale University P.O. Box 208109 New Haven CT 06520-8109 USA
| | - Chan Yu
- School of Energy & Environmental Engineering, University of Science and Technology Beijing 30 Xueyuan Road 100083 Beijing China
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Chang SJ, Blake RE. Oxygen isotope studies of phosphite oxidation: purification and analysis of reactants and products by high-temperature conversion elemental analyzer/isotope ratio mass spectrometry. Rapid Commun Mass Spectrom 2015; 29:2039-2044. [PMID: 26443404 DOI: 10.1002/rcm.7293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Increased attention has been recently focused on the origin and reactions of reduced-P oxyanions such as phosphite [PO3 (III)] in terrestrial and biological systems. We present new methods for studying O-isotopic reactions between PO3 (III) and other oxygen sources during oxidation of PO3 (III) to PO4 (V). METHODS Na2 (HPO3 )·5H2 O, used as a PO3 (III) source, contains structural water due to its hygroscopic nature; thus, we developed a method for determining the δ(18) O value of PO3 (III) after the removal of structural water. Next, we tested two techniques for purifying PO4 (V) from aqueous PO3 (III)/PO4 (V) mixtures: (1) precipitation of PO4 (V) as ammonium phosphomolybdate (APM); and (2) precipitation of PO4 (V) as magnesium ammonium phosphate (MAP). The O-isotope compositions, (18) O:(16) O (δ(18) O values), of Na2 (HPO3 ) and Ag3 PO4 were analyzed by TC/EA/IRMS. RESULTS Structural water was removed from Na2 (HPO3 )·5H2 O after drying at 100 °C under vacuum and the δ(18) O value of PO3 (III) was obtained. The δ(18) O values of PO4 (V), which was extracted from (18) O-labeled PO3 (III)/PO4 (V) mixtures by APM and MAP precipitations, were not altered by the precipitation process. This result confirms that PO3 (III) is not converted into PO4 (V) by oxidation or hydrolysis under either strong acidic/oxidizing (APM) or alkaline (MAP) conditions for up to a 24-h period. CONCLUSIONS We conclude that both APM and MAP precipitation are reliable and effective methods for the separation and purification of PO4 (V) from aqueous PO3 (III)/PO4 (V) mixtures. The methods described here will permit the study of the isotopic evolution of various pathways of geochemical as well as biological PO3 (III) oxidation.
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Affiliation(s)
- Sae Jung Chang
- Department of Geology and Geophysics, Yale University, New Haven, CT, 06511, USA
| | - Ruth E Blake
- Department of Geology and Geophysics, Yale University, New Haven, CT, 06511, USA
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Yu C, Yao J, Cai M, Wang F, Masakorala K, Liu H, Blake RE, Doni S, Ceccanti B. Functional gene expression of oil-degrading bacteria resistant to hexadecane toxicity. Chemosphere 2013; 93:1424-1429. [PMID: 23972733 DOI: 10.1016/j.chemosphere.2013.07.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 06/02/2023]
Abstract
Contamination with oil poses a threat to the environment and to human health worldwide. Biological methodologies have proved to be economical, versatile and efficient for the remediation of pollutants. In this paper, a highly efficient oil-degrading bacterial strain USTB-2 was isolated from an oil production well of Dagang oil field in Tianjin, China. The 16S rRNA sequence of USTB-2 showed 100% similarity with that of Bacillus subtilis BSn5. Hexadecane is one of the most important components in petroleum. The half inhibitory ratio (IC₅₀) of hexadecane inhibited organisms, determined by microcalorimetry, was lower in USTB-2 than in B. BSn5. The results indicate that the strain USTB-2 degrades hexadecane to make it less toxic compared with the normal strain. RT-PCR was used to evaluate the expression of oil-degrading enzymes, specifically 4-hydroxyphenylacetate 3-monooxygenase genes (HPMO). A sharp increase in the expression of HPMO genes was observed for USTB-2, while the expression of HPMO genes in reference strain B. BSn5 remained relatively stable. These methods can be used to study the metabolic potential of microorganisms for in situ oil decontamination.
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Affiliation(s)
- Chan Yu
- School of Civil & Environmental Engineering, National "International Cooperation Based on Environment and Energy", Key Laboratory of "Metal and Mine Efficiently Exploiting and Safety" Ministry of Education, University of Science and Technology Beijing, 100083 Beijing, PR China
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Sandy EH, Blake RE, Chang SJ, Jun Y, Yu C. Oxygen isotope signature of UV degradation of glyphosate and phosphonoacetate: tracing sources and cycling of phosphonates. J Hazard Mater 2013; 260:947-54. [PMID: 23892161 DOI: 10.1016/j.jhazmat.2013.06.057] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/05/2013] [Accepted: 06/22/2013] [Indexed: 06/02/2023]
Abstract
The degradation of phosphonates in the natural environment constitutes a major route by which orthophosphate (Pi) is regenerated from organic phosphorus and recently implicated in marine methane production, with ramifications to environmental pollution issues and global climate change concerns. This work explores the application of stable oxygen isotope analysis in elucidating the CP bond cleavage mechanism(s) of phosphonates by UV photo-oxidation and for tracing their sources in the environment. The two model phosphonates used, glyphosate and phosphonoacetic acid were effectively degraded after exposure to UV irradiation. The isotope results indicate the involvement of both ambient water and atmospheric oxygen in the CP bond cleavage and generally consistent with previously posited mechanisms of UV-photon excitation reactions. A model developed to calculate the oxygen isotopic composition of the original phosphonate P-moiety, shows both synthetic phosphonates having distinctly lower values compared to naturally derived organophosphorus compounds. Such mechanistic models, based on O-isotope probing, are useful for tracing the sources and reactions of phosphonates in the environment.
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Affiliation(s)
- Edward H Sandy
- State Key Laboratory of Biogeology & Environmental Geology, China University of Geosciences, Wuhan 430074, PR China
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Wang J, Wang F, Yao J, Guo H, Blake RE, Choi MMF, Song C. Effect of pH and Temperature on Adsorption of Dimethyl Phthalate on Carbon Nanotubes in Aqueous Phase. ANAL LETT 2013. [DOI: 10.1080/00032719.2012.713067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Larese-Casanova P, Blake RE. Measurement of δ18O values in arsenic and selenium oxyanions. Rapid Commun Mass Spectrom 2013; 27:117-126. [PMID: 23239324 DOI: 10.1002/rcm.6417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Revised: 09/22/2012] [Accepted: 09/23/2012] [Indexed: 06/01/2023]
Abstract
RATIONALE Past stable isotopic studies of selenium and arsenic oxyanions within a biogeochemistry context have focused solely on selenium isotopes due to monoisotopic nature of arsenic and lack of attention to oxygen. A modern quantification method of δ(18)O values in selenate, selenite, arsenate, and arsenite is presented here, similar to methods for other inorganic oxyanions such as phosphate. METHODS Dissolved oxyanions were recovered after precipitation with silver or barium cations within controlled pH ranges and purified by drying and roasting under vacuum. Oxygen isotope ratio measurements were performed on 250-450 micrograms of solids using continuous flow high-temperature conversion elemental analyzer/isotope ratio mass spectrometry (CF-TCEA/IRMS). Each Se and As solid was evaluated for reproducibility and stability of δ(18)O values and the usefulness of this method for evaluating aqueous phase Se and As oxyanion reactions was addressed. RESULTS Only silver arsenate and barium selenate were shown to have stable, reproducible δ(18)O values over 5 months and were calibrated to the VSMOW scale. The method was applied to confirm complete exchange of oxygen isotopes between arsenate and solvent water at pH 7 which produced an O-isotope fractionation between arsenate and water of 6.0‰. Furthermore, the method revealed the ability of oxygen in selenate to kinetically fractionate during reduction to elemental selenium by a green rust compound which produced a fractionation (20.9‰) larger than reported δ(80/76)Se values for similar reactions. CONCLUSIONS The experimental and analytical conditions for δ(18)O analysis of Se and As oxyanions were detailed. δ(18)O analyses of As and Se oxyanions may be useful in biogeochemical studies for tracing chemical reaction pathways, determining environmental sources of Se, or diagnosing specific reaction mechanisms for As and Se oxyanions.
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Affiliation(s)
- Philip Larese-Casanova
- Department of Geology & Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109, USA.
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Guo H, Yao J, Cai M, Qian Y, Guo Y, Richnow HH, Blake RE, Doni S, Ceccanti B. Effects of petroleum contamination on soil microbial numbers, metabolic activity and urease activity. Chemosphere 2012; 87:1273-80. [PMID: 22336736 DOI: 10.1016/j.chemosphere.2012.01.034] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/16/2012] [Accepted: 01/20/2012] [Indexed: 05/22/2023]
Abstract
The influence of petroleum contamination on soil microbial activities was investigated in 13 soil samples from sites around an injection water well (Iw-1, 2, 3, 4) (total petroleum hydrocarbons (TPH): 7.5-78 mg kg(-1)), an oil production well (Op-1, 2, 3, 4, 5) (TPH: 149-1110 mg kg(-1)), and an oil spill accident well (Os-1, 2, 3, 4) (TPH: 4500-34600 mg kg(-1)). The growth rate constant (μ) of glucose stimulated organisms, determined by microcalorimetry, was higher in Iw soil samples than in Op and Os samples. Total cultivable bacteria and fungi and urease activity also decreased with increasing concentration of TPH. Total heat produced demonstrated that TPH at concentrations less than about 1 g kg(-1) soil stimulated anaerobic respiration. A positive correlation between TPH and soil organic matter (OM) and stimulation of fungi-bacteria-urease at low TPH doses suggested that TPH is bound to soil OM and slowly metabolized in Iw soils during OM consumption. These methods can be used to evaluate the potential of polluted soils to carry out self-bioremediation by metabolizing TPH.
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Affiliation(s)
- Huan Guo
- School of Civil & Environmental Engineering, and National International Cooperation Base on Environment and Energy, University of Science and Technology Beijing, 100083 Beijing, PR China
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Jaisi DP, Kukkadapu RK, Stout LM, Varga T, Blake RE. Biotic and abiotic pathways of phosphorus cycling in minerals and sediments: insights from oxygen isotope ratios in phosphate. Environ Sci Technol 2011; 45:6254-6261. [PMID: 21732604 DOI: 10.1021/es200456e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A key question to address in the development of oxygen isotope ratios in phosphate (δ(18)O(p)) as a tracer of biogeochemical cycling of phosphorus in ancient and modern environments is the nature of isotopic signatures associated with uptake and cycling of mineral-bound phosphate by microorganisms. Here, we present experimental results aimed at understanding the biotic and abiotic pathways of P cycling during biological uptake of phosphate sorbed to ferrihydrite and the selective uptake of sedimentary phosphate phases by Escherichia coli and Marinobacter aquaeolei. Results indicate that a significant fraction of ferrihydrite-bound phosphate is biologically available. The fraction of phosphate taken up by E. coli attained an equilibrium isotopic composition in a short time (<50 h) due to efficient O-isotope exchange (between O in PO(4) and O in water; that is, actual breaking and reforming of P-O bonds) (biotic pathway). The difference in isotopic composition between newly equilibrated aqueous and residual sorbed phosphate groups promoted the ion exchange (analogous to isotopic mixing) of intact phosphate ions (abiotic pathway) so that this difference gradually became negligible. In sediment containing different P phases, E. coli extracted loosely sorbed phosphate first, whereas M. aquaeolei preferred Fe-oxide-bound phosphate. The presence of bacteria always imprinted a biotic isotopic signature on the P phase that was taken up and cycled. For example, the δ(18)O(p) value of loosely sorbed phosphate shifted gradually toward equilibrium isotopic composition. The δ(18)O(p) value of Fe-oxide-bound phosphate, however, showed only slight changes initially but, when new Fe-oxides were formed, coprecipitated/occluded phosphate retained δ(18)O values of the aqueous phosphate at the time of formation of new Fe oxides. Concentrations and isotopic compositions of authigenic and detrital phosphates did not change, suggesting that these phosphate phases were not utilized by bacteria. These findings support burgeoning applications of δ(18)O(p) as a tracer of phosphorus cycling in sediments, soils, and aquatic environments and as an indicator of paleo- environmental conditions.
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Affiliation(s)
- Deb P Jaisi
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, United States.
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Stout LM, Blake RE, Greenwood JP, Martini AM, Rose EC. Microbial diversity of boron-rich volcanic hot springs of St. Lucia, Lesser Antilles. FEMS Microbiol Ecol 2009; 70:402-12. [PMID: 19796138 DOI: 10.1111/j.1574-6941.2009.00780.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The volcanic Sulphur Springs, St. Lucia, present an extreme environment due to high temperatures, low pH values, and high concentrations of sulfate and boron. St. Lucia offers some unique geochemical characteristics that may shape the microbial communities within the Sulphur Springs area. We chose six pools representing a range of geochemical characteristics for detailed microbial community analyses. Chemical concentrations varied greatly between sites. Microbial diversity was analyzed using 16S rRNA gene clone library analyses. With the exception of one pool with relatively low concentrations of dissolved ions, microbial diversity was very low, with Aquificales sequences dominating bacterial communities at most pools. The archaeal component of all pools was almost exclusively Acidianus spp. and did not vary between sites with different chemical characteristics. In the pool with the highest boron and sulfate concentrations, only archaeal sequences were detected. Compared with other sulfur springs such as those at Yellowstone, the microbial diversity at St. Lucia is very different, but it is similar to that at the nearby Lesser Antilles island of Montserrat. While high elemental concentrations seem to be related to differences in bacterial diversity here, similarities with other Lesser Antilles sites suggest that there may be a biogeographical component as well.
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Affiliation(s)
- Lisa M Stout
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
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Jaisi DP, Saleh NB, Blake RE, Elimelech M. Transport of single-walled carbon nanotubes in porous media: filtration mechanisms and reversibility. Environ Sci Technol 2008. [PMID: 19068812 DOI: 10.1021/es801641vr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Deposition of nanomaterials onto surfaces is a key process governing their transport, fate, and reactivity in aquatic systems. We evaluated the transport and deposition behavior of carboxyl functionalized single-walled carbon nanotubes (SWNTs) in a well-defined porous medium composed of clean quartz sand over a range of solution chemistries. Our results showthat increasing solution ionic strength or addition of calcium ions result in increased SWNT deposition (filtration). This observation is consistent with conventional colloid deposition theories, thereby suggesting that physicochemical filtration plays an important role in SWNT transport. However, the relatively insignificant change of SWNT filtration at low ionic strengths (< or = 3.0 mM KCl) and the incomplete breakthrough of SWNTs in deionized water (C/Co = 0.90) indicate that physical straining also plays a role in the capture of SWNTs within the packed sand column. It is proposed that SWNT shape and structure, particularly the very large aspect ratio and its highly bundled (aggregated) state in aqueous solutions, contribute considerably to straining in flow through porous media. We conclude that both physicochemical filtration and straining play a role at low (< 3.0 mM) ionic strength, while physicochemical filtration is the dominant mechanism of SWNT filtration at higher ionic strengths. Our results further show that deposited SWNTs are mobilized (released) from the quartz sand upon introduction of low ionic strength solution following deposition experiments with monovalent salt (KCl). In contrast, SWNTs deposited in the presence of calcium ions were not released upon introduction of low ionic strength solution to the packed column, even when humic acid was present in solution during SWNT deposition.
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Affiliation(s)
- Deb P Jaisi
- Department of Chemical Engineering, Environmental Engineering Program, Yale University, New Haven, Connecticut 06520-8286, USA
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Jaisi DP, Saleh NB, Blake RE, Elimelech M. Transport of single-walled carbon nanotubes in porous media: filtration mechanisms and reversibility. Environ Sci Technol 2008; 42:8317-8323. [PMID: 19068812 DOI: 10.1021/es801641v] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Deposition of nanomaterials onto surfaces is a key process governing their transport, fate, and reactivity in aquatic systems. We evaluated the transport and deposition behavior of carboxyl functionalized single-walled carbon nanotubes (SWNTs) in a well-defined porous medium composed of clean quartz sand over a range of solution chemistries. Our results showthat increasing solution ionic strength or addition of calcium ions result in increased SWNT deposition (filtration). This observation is consistent with conventional colloid deposition theories, thereby suggesting that physicochemical filtration plays an important role in SWNT transport. However, the relatively insignificant change of SWNT filtration at low ionic strengths (< or = 3.0 mM KCl) and the incomplete breakthrough of SWNTs in deionized water (C/Co = 0.90) indicate that physical straining also plays a role in the capture of SWNTs within the packed sand column. It is proposed that SWNT shape and structure, particularly the very large aspect ratio and its highly bundled (aggregated) state in aqueous solutions, contribute considerably to straining in flow through porous media. We conclude that both physicochemical filtration and straining play a role at low (< 3.0 mM) ionic strength, while physicochemical filtration is the dominant mechanism of SWNT filtration at higher ionic strengths. Our results further show that deposited SWNTs are mobilized (released) from the quartz sand upon introduction of low ionic strength solution following deposition experiments with monovalent salt (KCl). In contrast, SWNTs deposited in the presence of calcium ions were not released upon introduction of low ionic strength solution to the packed column, even when humic acid was present in solution during SWNT deposition.
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Affiliation(s)
- Deb P Jaisi
- Department of Chemical Engineering, Environmental Engineering Program, Yale University, New Haven, Connecticut 06520-8286, USA
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Colman AS, Blake RE, Karl DM, Fogel ML, Turekian KK. Marine phosphate oxygen isotopes and organic matter remineralization in the oceans. Proc Natl Acad Sci U S A 2005; 102:13023-8. [PMID: 16141319 PMCID: PMC1201620 DOI: 10.1073/pnas.0506455102] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We show that the isotopic composition of oxygen (delta18O) in dissolved inorganic phosphate (Pi) reveals the balance between Pi transport and biological turnover rates in marine ecosystems. Our delta18Op of Pi (delta18Op) measurements herein indicate the importance of cell lysis in the regeneration of Pi in the euphotic zone. Depth profiles of the delta18Op in the Atlantic and Pacific Oceans are near a temperature-dependent isotopic equilibrium with water. Small deviations from equilibrium below the thermocline suggest that P remineralization in the deep ocean is a byproduct of microbial carbon and energy requirements. However, isotope effects associated with phosphohydrolase enzymes involved in P remineralization are quite large and could potentially lead to significant disequilibration of Pi oxygen. The observed near equilibration of deep water Pi likely calls for continued slow rates of microbial uptake and release of Pi and/or extracellular pyrophosphatase-mediated oxygen exchange between water and Pi along the deep water flow path.
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Affiliation(s)
- Albert S Colman
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
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Blake RE, Alt JC, Martini AM. Oxygen isotope ratios of PO4: an inorganic indicator of enzymatic activity and P metabolism and a new biomarker in the search for life. Proc Natl Acad Sci U S A 2001; 98:2148-53. [PMID: 11226207 PMCID: PMC30107 DOI: 10.1073/pnas.051515898] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (delta(18)O(p)) presented here. At low near-surface temperatures, the exchange of oxygen isotopes between phosphate and water requires enzymatic catalysis. Because enzymes are indicative of cellular activity, the demonstration of enzyme-catalyzed PO(4)-H(2)O exchange is indicative of the presence of life. Results of laboratory experiments are presented that clearly show that delta(18)O(P) values of inorganic phosphate can be used to detect enzymatic activity and microbial metabolism of phosphate. Applications of delta(18)O(p) as a biomarker are presented for two Earth environments relevant to the search for extraterrestrial life: a shallow groundwater reservoir and a marine hydrothermal vent system. With the development of in situ analytical techniques and future planned sample return strategies, delta(18)O(p) may provide an important biosignature of the presence of life in extraterrestrial systems such as that on Mars.
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Affiliation(s)
- R E Blake
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA.
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Simon JA, Robinson DE, Andrews MC, Hildebrand JR, Rocci ML, Blake RE, Hodgen GD. The absorption of oral micronized progesterone: the effect of food, dose proportionality, and comparison with intramuscular progesterone. Fertil Steril 1993; 60:26-33. [PMID: 8513955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES To examine the effects of food ingestion and administered dose on the absorption of oral micronized P (Utrogestan; Besins-Iscovesco, Paris, France) and to compare the bioavailability of intramuscular versus oral routes of administration. DESIGN Prospective, randomized, open label crossover protocol with 7 days between dosages. SETTING Academic institution. PARTICIPANTS Fifteen normal postmenopausal women. INTERVENTIONS All subjects participated in three separate protocols: [1] micronized P (200 mg) or placebo under fasting or nonfasting conditions once daily for 5 days; [2] micronized P (100, 200, or 300 mg) once daily under fasting conditions for 5 days; and [3] micronized P (200 mg) or intramuscular P (50 mg in oil) administered once daily for 2 days. MAIN OUTCOME MEASURES Serum P concentrations were measured in all groups. RESULTS Concomitant food ingestion increased the area under the serum P concentration versus time curve (AUC0 to 24) and the maximum serum P concentration (Cmax) without affecting time to maximum serum concentration (Tmax) (P < 0.05). Micronized P absorption and elimination were first-order processes and exhibited dose-independent pharmacokinetics between 100 and 300 mg. After intramuscular P, Cmax was higher and Tmax occurred later compared with the oral P preparation. Oral P had lower relative bioavailability (8.6%) than intramuscular P. CONCLUSIONS Absorption of micronized P was enhanced twofold in the presence of food. Both absorption and elimination were dose-independent, dose proportionality being confirmed. Bioavailability of the oral P was approximately 10% compared with intramuscular P.
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Affiliation(s)
- J A Simon
- Obstetrics and Gynecology, Georgetown University School of Medicine, Washington, D.C. 20007
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Blake RE, Rajguru S, Nolan GH, Ahluwalia BS. Dexamethasone suppresses sex-hormone binding globulin. Fertil Steril 1988; 49:66-70. [PMID: 3121398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Dexamethasone suppression (DEX-S) for 14 days has been used to determine the probable source of androgen excess. The exact mechanism(s) of DEX-S is still unclear. The authors postulated that dexamethasone (DEX) inhibits either the synthesis or secretion of sex-hormone binding globulin (SHBG). To examine this hypothesis, 14 women with polycystic ovarian disease (PCOD) and 3 volunteers were given DEX for 14 days. The PCOD group included obese and nonobese women (+/- 15% ideal body weight). Plasma determinations by radioimmunoassay of total testosterone, free testosterone, androstenedione, dehydroepiandrosterone sulfate, luteinizing hormone; follicle-stimulating hormone; cortisol, and SHBG were made. DEX suppressed SHBG levels (P less than 0.01). SHBG levels were significantly lower in the obese than in the nonobese (P less than 0.01). All androgens were suppressed by DEX, with the exception of androstenedione post-DEX levels, which were significantly greater than pre-DEX levels in 6 of 14 subjects (P greater than 0.05). This observation is consistent with DEX suppression of SHBG.
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Affiliation(s)
- R E Blake
- Department of Obstetrics and Gynecology, Howard University College of Medicine, Washington, D.C. 20060
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Blake RE, Maroulis GB, Sherman BM, Khalil A. Prolactinoma and adrenal androgens. J Reprod Med 1986; 31:675-9. [PMID: 3772886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Theories about the relationship between hyperprolactinemia and hyperandrogenism are conflicting. Several reports assert that prolactin affects the delta 5 and delta 4 pathways through its effect on the activity of 3beta-hydroxysteroid dehydrogenase (3beta-OHSD). We measured delta 5 and delta 4 steroids, prolactin and cortisol in 18 amenorrheic, hyperprolactinemic women before and after resection of prolactinomas. Similar determinations of delta 5: delta 4 steroids were made in a control group of five women. The ratios of individual delta 5: delta 4 steroids were also analyzed. Our results support a modification of delta 5, delta 4 pathways through an effect on the rate-limiting enzyme 3 beta-OHSD. In hyperprolactinemic women the differences between the preoperative and postoperative steroid levels were significant. Further, since the androgens decreased irrespective of the prolactin following surgery, there probably is a factor other than ACTH and prolactin modulating the adrenal androgens.
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Robertson BJ, Blake RE. Tuboplasty: use, resources, and nursing implications. Perioper Nurs Q 1985; 1:49-56. [PMID: 2409550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Blake RE. Preventive podiatry in a Veterans Administration hospital. J Am Podiatry Assoc 1967; 57:78-80. [PMID: 6039780 DOI: 10.7547/87507315-57-2-78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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