Assessment and Control of Arsenic Mobility in Contaminated Sediments

EPA Grant Number: R826202
Title: Assessment and Control of Arsenic Mobility in Contaminated Sediments
Investigators: Hering, Janet G.
Institution: California Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1997 through September 30, 2000 (Extended to March 31, 2001)
Project Amount: $288,049
RFA: Contaminated Sediments (1997) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation , Land and Waste Management


The issue of arsenic storage in, and potential release from, sediments is particularly pertinent to future management of the water supply to the City of Los Angeles. Water imported through the L.A. Aqueduct contains elevated arsenic concentrations derived from inputs of geothermal water in the Eastern Sierra Nevada. Since the geothermal input of arsenic is relatively localized, treatment to remove arsenic near the source may be feasible. The effectiveness of this strategy may be limited if arsenic stored in the reservoir sediments downstream of the potential near-source treatment site were to be remobilized. The proposed project will determine whether: (1) recycling of arsenic from the sediments to the water column is likely to increase in response to a decrease in arsenic concentrations in the overlying water, (2) arsenic mobility in the sediments can be related to the bulk composition (specifically iron and manganese content) and the redox status of the sediments, (3) mobility of arsenic in sediments is correlated with sediment toxicity, (4) sediments in the L.A. Aqueduct system store sufficient arsenic that its release could impact the quality of water supplied to the City of Los Angeles, and (5) arsenic could be stabilized in sediments by increasing the sediment iron content.


The project will involve the collection and analysis of arsenic (and other redox-active chemical species) in sediments and porewaters from Hot Creek Gorge, the Owens River, Lake Crowley, and Lake Haiwee. The range of arsenic concentrations in the sediments and vertical gradients in arsenic concentration and speciation will be assessed. Vertical profiles of arsenic in the water column of Lake Crowley will also be determined. Sediment-water exchange processes in response to changes in arsenic concentrations in the overlying water will be examined in laboratory microcosms and the effects of ferric chloride additions evaluated. Toxicity of the sediments will be assessed by microbial toxicity screening.

Expected Results:

The potential for arsenic release from reservoir sediments in the L.A. Aqueduct system in response to the implementation of control technology for arsenic removal near the source of geothermal arsenic inputs on Hot Creek will be evaluated. Possible measures for mitigating arsenic remobilization (e.g., by increasing the iron content of sediments) will also be assessed. On a more fundamental level, the information gained from the study of this specific system will improve our understanding of the biogeochemical cycling of arsenic in sediments.

Publications and Presentations:

Publications have been submitted on this project: View all 9 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 2 journal articles for this project

Supplemental Keywords:

drinking water, watersheds, sediments, toxicity., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Water, Geographic Area, Waste, POLLUTANTS/TOXICS, Environmental Chemistry, Contaminated Sediments, Health Risk Assessment, Geochemistry, Arsenic, State, Water Pollutants, Ecological Risk Assessment, Drinking Water, reservoir sediments, monitoring, arsenic remobilizatrion, contaminant transport, exposure and effects, contaminated sediment, sediment transport, geothermal water inputs, exposure, risk management, microbial pollution, sediment quality survey, treatment, microbial risk management, arsenic mobility, assessment methods, water quality, arsenic exposure, California (CA), ecology assessment models, water treatment, drinking water contaminants

Progress and Final Reports:

  • 1998
  • 1999
  • 2000
  • Final Report