Environmental Chemistry of Bioavailability in Sediments and Water Column

EPA Grant Number: R825433C007
Subproject: this is subproject number 007 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Environmental Chemistry of Bioavailability in Sediments and Water Column
Investigators: Higashi, Richard M.
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


To study the soil and sediment matrix chemistry that controls the accumulation, transformation and release of pollutant chemicals. The matrix chemistry, principally of organic matter and minerals, is also used to "fingerprint" the history and sources of sediment.


In classical toxicology, the "dose makes the poison." "Bioavailability" is a concept that attempts to apply this maxim to ecotoxicology. This Analytical and Biomarkers Core project explores the chemical basis of bioavailability at several project linkage points in the Sacramento River-Delta/San Francisco Bay (SRD/SFB) Watershed study section.

In bioactive soil and sediment systems, the production of organic ligands known as siderophores is the principal mechanism by which primary and secondary producers acquire nutrient metals. Thus the effect of these and other biogenic ligands tend to occur at the major points where toxic metals enter the food chain. Since any and all ligands can interplay, it is crucial to take as complete a stock of the players as possible. Our manuscript describing an approach to both comprehensive (broad) and detailed (depth) analysis of such ligands has just been accepted by the journal Phytochemistry.

Metal ion transport and bioavailability has, for lack of studies to the contrary, assumed competition of the free toxic ions between sites such as sediment organic material, counterion ligands, and organisms. However, using the ability of NMR to directly measure chemical binding rates, we have discovered that a common bacterial siderophore of the hydroxamate chemical class, desferrioxamine, binds extensively to humic materials, thereby limiting the binding of metals to the siderophore. As both siderophore and humics are very powerful metal-binders in real soils, this finding potentially changes the fundamental chemical assumptions (i.e. competition) regarding metal availability and transport. As reported previously, a manuscript of this research has appeared in The Analyst in 1998.

It is equally vital to understand the nature of the complex binding sites of natural humics, which can "coat" soil and sediment particles and thereby define a majority of metal-binding. Because its origins are degraded biological material, humics are also very dynamic in its properties. Pyrolysis-GCMS is used to rapidly screen structure information on humic materials, which is anchored with other analytical techniques such as NMR, FTIR, and energy-dispersive X-ray fluorescence (ED-XRF) to greatly extend its interpretability. A manuscript describing humic surface properties, utilizing all of these techniques and more, has been published this year in Environmental Science and Technology.

Expected Results:

The investigators focusing on aspects of selenium (Se) biogeochemistry, and its biological impacts in the SRD/SFB Watershed study section. The biochemical and environmental organic forms in food organisms and sediments, repectively, could hold the key to understanding of Se ecotoxic effects. The key concept remains bioavailability of the toxicant, in this case, unknown organic Se forms. The investigators plan to cross this study of selenium with the organic matter research described above.

Publications and Presentations:

Publications have been submitted on this subproject: View all 4 publications for this subprojectView all 403 publications for this center

Journal Articles:

Journal Articles have been submitted on this subproject: View all 4 journal articles for this subprojectView all 240 journal articles for this center

Supplemental Keywords:

wetlands, bioavailability, environmental toxins, food chain, ligands, environmental chemistry, selenium., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Geographic Area, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Restoration, State, Aquatic Ecosystem, Ecological Effects - Environmental Exposure & Risk, Biochemistry, Environmental Monitoring, Terrestrial Ecosystems, Ecological Monitoring, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Watersheds, nutrient dynamics, watershed development, Clear Lake , ecosystem monitoring, watershed management, fish habitat, watershed, anthropogenic effects, agricultural watershed, nutrient flux, biogeochemcial cycling, aquatic habitat, Clear Lake, watershed land use, watershed modeling, ecological assessment, hydrology, integrated watershed model, lakes, aquatic ecosystems, environmental stress, lake ecosysyems, water quality, ecosystem stress, hydrologic modeling, Lake Tahoe, California (CA), ecology assessment models, environmental stress indicators, water management options, ecosystem response, land use

Progress and Final Reports:

  • 1997
  • 1998
  • 1999
  • Final Report

  • Main Center Abstract and Reports:

    R825433    EERC - Center for Ecological Health Research (Cal Davis)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
    R825433C002 Sacramento River Watershed
    R825433C003 Endocrine Disruption in Fish and Birds
    R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
    R825433C005 Fish Developmental Toxicity/Recruitment
    R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
    R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
    R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
    R825433C009 Modeling Ecosystems Under Combined Stress
    R825433C010 Mercury Uptake by Fish
    R825433C011 Clear Lake Watershed
    R825433C012 The Role of Fishes as Transporters of Mercury
    R825433C013 Wetlands Restoration
    R825433C014 Wildlife Bioaccumulation and Effects
    R825433C015 Microbiology of Mercury Methylation in Sediments
    R825433C016 Hg and Fe Biogeochemistry
    R825433C017 Water Motions and Material Transport
    R825433C018 Economic Impacts of Multiple Stresses
    R825433C019 The History of Anthropogenic Effects
    R825433C020 Wetland Restoration
    R825433C021 Sierra Nevada Watershed Project
    R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
    R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
    R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
    R825433C025 Regional Movement of Toxics
    R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
    R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
    R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
    R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
    R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
    R825433C031 Pre-contact Forest Structure
    R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
    R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
    R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
    R825433C035 Border Rivers Watershed
    R825433C036 Toxicity Studies
    R825433C037 Watershed Assessment
    R825433C038 Microbiological Processes in Sediments
    R825433C039 Analytical and Biomarkers Core
    R825433C040 Organic Analysis
    R825433C041 Inorganic Analysis
    R825433C042 Immunoassay and Serum Markers
    R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
    R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
    R825433C045 Microbial Community Assays
    R825433C046 Cumulative and Integrative Biochemical Indicators
    R825433C047 Mercury and Iron Biogeochemistry
    R825433C048 Transport and Fate Core
    R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
    R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
    R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
    R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
    R825433C053 Currents in Clear Lake
    R825433C054 Data Integration and Decision Support Core
    R825433C055 Spatial Patterns and Biodiversity
    R825433C056 Modeling Transport in Aquatic Systems
    R825433C057 Spatial and Temporal Trends in Water Quality
    R825433C058 Time Series Analysis and Modeling Ecological Risk
    R825433C059 WWW/Outreach
    R825433C060 Economic Effects of Multiple Stresses
    R825433C061 Effects of Nutrients on Algal Growth
    R825433C062 Nutrient Loading
    R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
    R825433C064 Chlorinated Hydrocarbons
    R825433C065 Sierra Ozone Studies
    R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
    R825433C067 Terrestrial - Agriculture
    R825433C069 Molecular Epidemiology Core
    R825433C070 Serum Markers of Environmental Stress
    R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
    R825433C072 Molecular Monitoring of Microbial Populations
    R825433C073 Aquatic - Rivers and Estuaries
    R825433C074 Border Rivers - Toxicity Studies