Archived Publication Announcements

June 22 2016

Importance of Young Dissolved Organic Carbon to the Release of Arsenic in Arsenic Impacted Aquifers

On June 22, 2016, the journal Environmental Science & Technology published a paper by Columbia SRP scientists Brian Mailloux, Alexander van Geen, Benjamin Bostick and colleagues Kelly Whaley-Martin, Greg Slater, Rachel Silvern, Carol Kim, Kazi Matin Ahmed, and Imtiaz Choudhury titled, “Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids.” Arsenic contamination affects the drinking water of millions of people around the world. In the majority of these environments, arsenic is released from sediments to the water through biological respiration that changes the chemical form of the closely associated arsenic and iron. This respiration requires organic carbon, yet the sources of this organic carbon driving the microbially-mediated release of arsenic to shallow groundwater, remain poorly understood. The study reported in this publication sheds light on this question using a novel method of characterizing the radiocarbon age of phospholipid fatty acids (PLFAs), molecules that are part of cellular wall material in all living organisms and are indicative of living organisms. This method established that the microbial respiration in aquifers containing arsenic uses carbon that is much younger than the carbon in the sediments, and similar in age to dissolved organic carbon, much of which is derived from near-surface environments. This observation implies that these young carbon substrates are used in the microbial reduction of sedimentary iron oxides that are known to release arsenic into solution. The methods used in this study are particularly powerful because they allow scientists to study these microbiological processes in complex field environments, establishing which carbon is being used for respiration, and to gain insight into how those processes effect aquifer water quality. The research findings suggest that near-surface sources of organic carbon are central in microbial metabolism even in aquifers that are spatially separated from the land surface from which this carbon is derived. This indicates that dissolved organic carbon is efficiently and rapidly transported into the aquifer. Since this dissolved organic carbon is transported in water, there must be a hydrological connection between shallow sources and the aquifer, and water must be efficiently transported from shallow sources to depth. Given that one of the sites examined in this study is covered by a thick clay that is laterally extensive, it appears that groundwater can circumvent this barrier, and that these barriers may not be as protective of water quality as previously believed. This field study establishes that young organic carbon derived from the surface can negatively affect arsenic concentrations and water quality within an aquifer. In the United States half of all Superfund sites are contaminated with arsenic. In these Superfund sites, similar changes in groundwater hydrology and/or the input of other organic wastes (for example, in landfills) or organic chemicals at industrial sites, also has the potential to adversely impact groundwater arsenic levels and overall water quality. These radiocarbon methods can also be applied to these other areas to understand the origin of arsenic contamination and how to target and optimize remediation efforts at these contaminated sites.

Citation: 

Whaley-Martin KJ, Mailloux BJ, van Geen A, Bostick BC, Silvern RF, Kim C, Ahmed KM, Choudhury I, Slater GF. Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids. Environmental Science & Technology. 2016 Jun 22; 50:7353–7363. http://dx.doi.org/10.1021/acs.est.6b00868

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March 31 2016

How would arsenic behave in sulfidic environment?

Contributing to the development of solutions to the difficult problem of remediating aquifers with elevated dissolved arsenic concentrations, Columbia SRP postdoctoral researcher Jing Sun in collaboration with Andrew Quicksall of Southern Methodist University and Columbia SRP scientists from Projects 4 and 5 Steven Chillrud, Brian Mailloux, and Benjamin Bostick have published an article in the June 2016 issue of Chemosphere titled “Arsenic mobilization from sediments in microcosms under sulfate reduction.” The team is focused on designing and evaluating enhanced remediation approaches for sites with arsenic contaminated groundwater. Arsenic sulfide precipitation has often been suggested as a remediation option for such sites. In this paper, they reported results from laboratory studies where they stimulated microbial sulfate reduction within microcosms containing contaminated sediments, and evaluated whether this process would immobilize arsenic for use in groundwater remediation. The sediments used were collected from two distinct sites: the Vineland Chemical Company Superfund site in southern New Jersey and a former heavy metal sulfide mining site, the Coeur d’Alene mining district in northern Idaho. The research team found that although transient arsenic removal from solution occurred in microcosms with these sediments, overall arsenic was released from sediments to solution. Based on this study and other published studies on sulfate reduction, the research team has proposed a generalized conceptual model that describes how iron and sulfur are cycled in a sulfidic environment, which includes both insoluble sulfide minerals and soluble sulfide complexes, to better ascertain conditions under which sulfide phases immobilize arsenic. The article was initially published online on March 31, 2016.

Citation:

Sun J, Quicksall AN, Chillrud SN, Mailloux BJ, Bostick BC. Arsenic mobilization from sediments in microcosms under sulfate reduction. Chemosphere 2016 June; 153:254–261.

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February 27 2016

Oxalic acid is a promising amendment for enhanced pump-and-treat to remediate groundwater arsenic contamination

Columbia SRP postdoctoral researcher Jing Sun along with Columbia SRP scientists from Projects 4 and 5 Benjamin Bostick, Brian Mailloux, Jamie Ross, and Steven Chillrud have published an article reporting their research to address the challenging task of remediating aquifers with elevated dissolved arsenic concentrations. Traditional pump-and-treat approaches are used at many arsenic contaminated aquifer sites even though the mass transfer of arsenic off of sediments is slow. Our group has investigated whether in situ injections of oxalic acid can increase the mass transfer into the aqueous phase, which is removed by pumping, and thus decrease the time required for effective remediation. In this paper, the team focused on whether residual sediment arsenic after oxalic acid treatment can still be reductively mobilized. The sediments used were from the Dover Municipal Landfill (Dover, New Hampshire) and the Vineland Chemical Company (Cumberland County, New Jersey) Superfund sites, which had different arsenic input sources, levels, and redox conditions. Batch extraction, column, and microcosm experiments were performed on the sediments in the laboratory. The authors found that oxalic acid mobilized arsenic from both Dover and Vineland sediments, although at different efficiency rates. They also found that the residual arsenic in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment but that there was still sufficient labile arsenic in the treated Vineland sediments to make them vulnerable under reducing conditions. Thus, they conclude that oxalic acid could potentially improve the efficiency of the widely used pump-and-treat remediation. The study “Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions” is reported in the July 2016 issue of the Journal of Hazardous Materials. The article was initially published online on February 27, 2016.

Citation:

Sun J, Bostick BC, Mailloux BJ, Ross JM, Chillrud SN. Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions. Journal of Hazardous Materials 2016 July; 311:125–133.

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October 23 2015

A Potential Long-Term Arsenic Immobilization Strategy by Nitrate-Iron(II) Addition

Columbia SRP student Jing Sun, Columbia SRP scientists Steven Chillrud, Brian Mailloux, Martin Stute, and Benjamin Bostick, along with colleagues Rajesh Singh, Hailiang Dong, and Christopher Lepre have co-authored a publication in the journal Chemosphere entitled, "Enhanced and stabilized arsenic retention in microcosms through the microbial oxidation of ferrous iron by nitrate." The article reports the results of laboratory microcosm experiments conducted to investigate a potential As remediation method involving magnetite formation, using groundwater and sediments from the Vineland Chemical Company Superfund site in Cumberland County, New Jersey. The authors found that magnetite is an advantageous host-mineral for As immobilization. The study represents an initial attempt to produce relatively stable As sequesters by simultaneous addition of ferrous Fe and nitrate. The paper was published online on October 23, 2015. The print version will be available in the February 2016 issue of Chemosphere. Benjamin Bostick is the corresponding author.

Citation: Sun J, Chillrud SN, Mailloux BJ, Stute M, Singh R, Dong H, Lepre CJ, Bostick BC. Enhanced and stabilized arsenic retention in microcosms through the microbial oxidation of ferrous iron by nitrate. Chemosphere 2016 Feb; 144:1106–1115. http://dx.doi.org/10.1016/j.chemosphere.2015.09.045

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June 26 2015

Diverse Stakeholders Partner to Reduce Arsenic Exposure and Health Effects

Following the Human and Environmental Sustainability Summit on Environmental and Human Health Consequences of Arsenic in August 2014, participants from both public and private sectors, including CU SRP RTC scientist Meredith Golden, collaborated to co-author, “MDI Biological Laboratory Arsenic Summit: Approaches to Limiting Human Exposure to Arsenic”. This paper summarizes the summit findings and proposes a plan for reducing arsenic exposure globally through innovative policies and effective actions. The lead author and the Summit convener, Dr. Bruce Stanton is the Director of the Dartmouth Superfund Research Program. The paper was published online on June 26, 2015 by Current Environmental Health Reports (dx.doi.org/10.1007/s40572-015-0057-9). The print version will be available in the September issue.

Citation:

Stanton, B.A., et al. MDI Biological Laboratory Arsenic Summit: Approaches to Limiting Human Exposure to Arsenic. Current Environmental Health Reports, September 2015, Volume 2, Issue 3, pp 329-337. Available online 26 June 2015. DOI 10.1007/s40572-015-0057-9.

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May 15 2015

CU SRP Randomized Trial Shows High Daily Dose of Folic Acid Alone Lowers Blood Arsenic

CU SRP student Brandilyn Peters and scientist Dr. Megan Hall, along with Dr. Gamble (PI, R01 CA133595 and PI of CU-SRP Project 3), investigate the impact of folate and/or creatine supplements in reducing blood arsenic levels in Bangladeshi adults. Ingested arsenic undergoes hepatic methylation generating mono- and di-methylated arsenicals; the latter are more readily excreted in urine. Folic acid and creatine supplementation, by influencing the availability of methyl groups, have the potential to enhance arsenic methylation. We have found previously that folic acid enhances arsenic methylation and lowers blood arsenic in folate deficient individuals. In a new randomized, placebo-controlled trial of 622 Bangladeshi adults, we tested whether folic acid and/or creatine supplementation lowers blood arsenic in a mixed folate replete/deficient study population. We found that supplementation with 800 ug folic acid/day lowered blood arsenic to a greater extent than placebo over the 12 and 24 week time periods of the trial, while the other treatments (400 ug folic acid/day, 3 g creatine/day, and 3 g creatine + 400 ug folic acid/day) did not. Folate fortification in arsenic-endemic countries may facilitate a partial reduction in the public health burden of arsenic exposure. The manuscript “Folic acid and creatine as therapeutic approaches to lower blood arsenic: A Randomized-Controlled Trial” is available as an Advance Publication on the Environmental Health Perspectives web site as of May 15, 2015. The copyedited and formatted version will appear online and in print soon.

Citation:
*Peters BA, *Hall MN, Liu X, Parvez F, Siddique AB, Shahriar MH, Slavkovich V, Ilievski V, Factor-Litvak P, Graziano JH, Gamble MV. Folic acid and creatine as therapeutic approaches to lower blood arsenic: A Randomized-Controlled Trial.  Envir Health Persp May 15, 2015 (ePub ahead of print). DOI:10.1289/ehp.1409396

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April 23 2015

Does oxidized plasma glutathione redox potential increase inflammation and renal dysfunction in arsenic exposed Bangldeshi adults?

Columbia SRP student Brandilyn Peters, along with her CU SRP colleagues, found that study participants with lower plasma GSH and more oxidized plasma EhGSH were at risk of increased As-induced inflammation. Their paper, “Arsenic exposure, inflammation, and renal function in Bangladeshi adults: Effect modification by plasma glutathione redox potential” was published online in the April edition of Free Radical and Biology Medicine. The printed version should be available soon.

Arsenic exposure may cause inflammation and renal dysfunction via induction of oxidative stress. The plasma glutathione redox potential reflects an individual’s exposure to oxidative stress which may modify risk for arsenic-induced health outcomes. In a cross-sectional study of Bangladeshi adults, we tested whether arsenic exposure was associated with increased inflammation and decreased renal function, and whether these effects were stronger among those with a more oxidized plasma glutathione redox potential. Water, blood, and urinary arsenic were positively associated with plasma C-reactive protein, a biomarker of inflammation, only in participants with a more oxidized plasma glutathione redox potential. Blood and urinary arsenic had marginal negative associations with estimated glomerular filtration rate, and these associations were not significantly modified by the plasma glutathione redox potential. Antioxidants should be explored as a treatment to prevent arsenic-induced inflammation.

Citation:
Peters BA, Liu X, Hall MN, Ilievski V, SlavkovichV, Siddique AB, Alam S, Islam T, Graziano JH and Gamble MV.  Arsenic exposure, inflammation and renal function in Bangladeshi adults:  effect modification by plasma glutathione redox potential.  Free Rad Biol Med April 23, 2015 (ePub ahead of print). DOI:10.1016/j.freeradbiomed.2015.04.020. 

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February 1 2015

Columbia SRP Scientists and Partners Contribute to Special STOTEN Arsenic Issue

CU SRP Community Engagement PI Yan Zheng and and USGS Hydrologist Joseph Ayotte together have edited a special section on arsenic for the journal Science of the Total Environment (STOTEN), Volume 505, 1 February 2015. Their summary paper, “At the crossroads: Hazard assessment and reduction of health risks from arsenic in private well waters of the northeastern United States and Atlantic Canada” is the first in a collection of thirteen papers that provides state-of-the-art information on arsenic (AS) hydrogeochemistry, effectiveness of household well treatment systems, and the testing and treatment decisions of private well owners in several northeastern U.S. states and in Nova Scotia, Canada. The Zheng-Ayotte paper and the special Arsenic section are available now online (see link below).

A total of 5 papers in the STOTEN special issue are also co-authored by Columbia SRP scientists and their partners. They include CU SRP Community Engagement and Research Translation Core scientists Yan Zheng and Sara V. Flanagan, CU project scientist Martin Stute, former trainee Qiang Yang (now Lamont Associate Research Scientist), former CU SRP post doc Beth O’Shea (now Assistant Professor at University San Diego), and government collaborators Joseph Ayotte (USGS, New England Water Science Center New Hampshire-Vermont Office), Robert Marvinney (Maine Geological Survey), Charles Culbertson (USGS , Maine Water Science Center), and Steve Spayd (NJ Geological Survey).

Zhang and Ayotte conclude in their summary that there must be an overall, long-term strategy to reduce exposure to vulnerable populations in regions where levels of arsenic in well-water are high. More consideration is needed to encourage well testing, treatment, access to alternative water sources, and possible implementation of local, state, and regional private well-water regulations.

Citation:
Zheng, Yan and Joseph D. Ayotte. At the crossroads: Hazard assessment and reduction of health risks from arsenic in private well waters of the northeastern United States and Atlantic Canada. Science of The Total Environment, Volume 505, 1 February 2015, Pages 1237-1247. Available online 18 November 2014, doi:10.1016/j.scitotenv.2014.10.089.

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January 22 2015

CU SRP Student Howe and Scientist Gamble describe differential cleavage of histone H3 which interferes with the measurement of downstream modifications

Histone modifications are increasingly being used as biomarkers of cancer prognosis and survival. They are also novel targets of interest for environmental epidemiology studies. However, Columbia SRP student Caitlin Howe and Project 3 PI Dr. Mary Gamble recently identified a cleavage product of histone H3 in human peripheral blood mononuclear cells (PBMCs), which interferes with the measurement of downstream modifications, such as H3K9me2. They reported this finding earlier this year in a Letter to the Editor, which was published in Clinical Epigenetics, the official journal of the Clinical Epigenetics Society. H3 cleavage has been described in many other species, and several groups have hypothesized that this occurs in vivo. Cleavage of H3 has also been observed in human cell lines. However, there have been few reports of H3 cleavage in human biological samples. Ms. Howe and Dr. Gamble emphasize that it remains unclear if the H3 cleavage product identified in human PBMCs is an artifact of sample collection, or if H3 cleavage occurred in vivo, but either conclusion has important implications for molecular epidemiology studies, as the former would necessitate a better understanding of when and why H3 cleavage occurs, so preventive measures can be developed, while the latter suggests that there may be an important biological function of H3 cleavage that merits additional study.

Citation:
Howe CG and Gamble MV.  Enzymatic cleavage of histone H3: a new consideration when measuring histone modifications in human samples.  Clin Epigen 2015 Jan 22; 7(1):7.  PMCID:PMC4307743 doi: 10.1186/s13148-014-0041-5

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January 1 2015

Association of Epigenetic Modifications with Arsenic Toxicity Point to Potential Pathways for Intervention

Dr. Maria Argos along with other Columbia SRP scientists Mary Gamble, Kristin Harper, Faruque Parvez, Joseph Graziano, and Habibul Ahsan studied the association between arsenic exposure and epigenome-wide white blood cell DNA methylation in a population of 400 Bangladeshi adults. Arsenic exposure was measured in terms of blood and urinary total arsenic concentrations. The study “Gene-Specific Differential DNA Methylation and Chronic Arsenic Exposure in an Epigenome-Wide Association Study of Adults in Bangladesh” was published in the January issue of Environmental Health Perspectives. The authors concluded that there are significant associations between arsenic exposure and gene-specific white blood cell DNA methylation. Thus, epigenetic modifications may be key to arsenic toxicity. Details from this study reveal “specific differentially methylated loci” and, thus, may help target key pathways for future interventions.

Citation:
Argos M, Chen L, Jasmine F, Tong L, Pierce BL, Roy S, Paul-Brutus R, Gamble MV, Harper KN, Parvez F, Rahman M, Rakibuz-Zaman M, Slavkovich V, Baron JA, Graziano JH, Kibriya MG, Ahsan H.  Gene-specific differential DNA methylation and chronic arsenic exposure in an epigenome-wide association study of adults in Bangladesh.  Environ Health Perspect 2015 Jan; 123(1):64-71.  PMCID: PMC4286273. Doi: 10.1289/ehp.1307884

 

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