Research Project 12
| EPA Grant Number: | R828771-0-01 |
| Title: | Seasonal Controls of Arsenic Transport Across the Groundwater-Surface Water Interface at a Closed Landfill Site |
| Investigators: |
Allison MacKay (UCONN), Barth Smets (UCONN) and Howard Fairbrother (JHU) |
| Institution: |
University of Connecticut |
| Project Period: |
October 1, 2003 to September 30, 2004 |
| Description: |
| Arsenic transport from the auburn road landfill leachate plume across the groundwater/surface water interface of Cohas Brook is controlled by the formation of iron oxides in these sediments. In particular, iron oxidizing bacteria are present in these sediments and may play a central role in generation of iron oxyhydroxide solids because abiotic iron oxidation is extremely slow (t½=300d) given the pore water chemistry in the groundwater/surface water interface. |
| Objectives: |
| We hypothesize that iron
oxidizing and iron reducing bacteria control the seasonal transport of
arsenic across the GSI at Cohas Brook through the production and
dissolution of iron oxyhydroxide particles in near shore sediments.
The ultimate goal of the research is to identify the seasonal cycle of
arsenic sequestration and release between sediments and pore water in the
groundwater/surface water interface and will be met by the following
objectives: 1. Quantify seasonal distributions of arsenic, iron and sulfur species and other key electron donating/accepting species relative to the GSI 2. Determine the significance of microbial and chemical iron oxidation in the GSI, including temporal and spatial trends, and 3. Characterize the composition and crystallinity of iron solids, including arsenic associations and speciation in oxyhydroxide precipitates newly formed in the field or under chemically - or microbially - enhanced laboratory conditions. |
| Expected Results: |
| The key chemical or biological processes that control the fate of arsenic transport the groundwater/surface water interface will be deduced from the high resolution patterns of pore water chemistry and solid precipitates observed at Cohas Brook. These observations will indicate the conditions under which arsenic sequestration in sediments limits the transport of arsenic from groundwater to surface water at this, and other hydrogeologically similar sites in New England. Ultimately results will direct the future development of predictive models of arsenic transport and lead to effective remediation approaches for abandoned landfill sites. |
| Supplemental Keywords: |
| arsenic, iron oxides, sulfur species, remediation, landfill |