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Final Progress Reports: Columbia University: The Resilience of Low-Arsenic Aquifers and their Role in Reducing Human Exposure

Superfund Research Program

The Resilience of Low-Arsenic Aquifers and their Role in Reducing Human Exposure

Project Leader: Alexander F. van Geen
Co-Investigators: Benjamin C. Bostick, Ana Navas-Acien
Grant Number: P42ES010349
Funding Period: 2000-2021

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Final Progress Reports

Year:   2020  2016  2010  2005 

2005 saw the publication of two papers describing significant advances in the application of iron filings as a medium for removing arsenic.  The first, by Nikolaidis et al. which appeared in a volume of the ACS Symposium Series devoted to arsenic, demonstrates that the medium can be used at the household level in Bangladesh to treat groundwater containing elevated As concentrations.  The second, by Cheng et al., which appeared in Environmental Science & Technology, showed that some (but not all) organic As species abundantly present in groundwater at the Vineland Chemical Superfund site in New Jersey can effectively be removed by passage through a column of Fe filings.  The significance of this work is that the polishing of plant effluent with Fe filings could significantly reduce the cost of pump and treat operations at the site, as state standards for the composition of the effluent from the plant become more stringent.

2005 also saw the publication of three studies addressing the fundamental controls of As mobilization in reducing aquifers.  The first, by Cheng et al., which appeared in Environmental Science & Technology, demonstrated that temporal variations in groundwater As concentrations can be significant but are limited only to the very shallowest (i.e., <10 m deep) aquifers of Bangladesh.  This is consistent with groundwater dating conducted by the Zheng/Stute project showing that seasonal and interannual variations in groundwater composition are likely to be dampened in older, deeper strata.  The second paper, by Thoral et al., which also appeared in Environmental Science & Technology, shows that the presence of As significantly alters the process of Fe(II) oxidation and limits the size of Fe oxide particles to the point where As removal by filtration is hampered.  Beyond practical implications for treatment, the formation of relatively mobile As-enriched Fe colloids in response to seasonal redox fluctuations could play a significant role in propagating changes in surface forcing to naturally enriched, shallow aquifers.  The third paper, by van Geen et al., scheduled to appear in Chemical Geology, has provided complementary information on the processes prevailing in shallow aquifer by mapping the distribution of groundwater and sediment properties at an unprecedented spatial resolution of ~100 m laterally and ~2 m vertically.  The new observations, when linked to hydrological and geophysical observations in the same study area of Bangladesh, show that despite tremendous variability, groundwater As concentrations in shallow aquifers are predictably related to local variations in recharge and groundwater flow.

van Geen’s lab continues to direct efforts to lower As exposure in Columbia University’s study area in Bangladesh, while extracting generalizable lessons from these activities.  A significant finding, published by van Geen et al. in Environmental Science & Technology., has been that the field-kit for As that is presently most widely used in Bangladesh performs rather well in terms of As detection in groundwater.  In a forthcoming paper in Health & Place that the mere testing and labeling of tube wells, coupled with the installation of 50 deep, arsenic-free community wells has induced two-thirds of the exposed population to change their source of water.

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