Final Report: 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: Hahn, Intaek
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


The objective of this research project was 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, also was used to "fingerprint" the history and sources of sediment and soil. This project was conducted in collaboration with Project R825433C046 (Higashi).

Summary/Accomplishments (Outputs/Outcomes):

In classical toxicology, the "dose makes the poison." "Bioavailability" is a concept that attempts to apply this maxim to ecotoxicology. This research project explores the chemical basis of bioavailability at several project linkage points in the Sacramento River Delta/San Francisco Bay 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 tends to occur at the major points where toxic metals enter the food chain. Because 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 been published by the journals Analytical Biochemistry and Phytochemistry.

Metal ion transport and bioavailability has, for lack of studies to the contrary, assumed simple competition of the free toxic ions between sites such as sediment organic material, counterion ligands, and organisms. However, using the ability of nuclear magnetic resonance (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. A manuscript of this research has appeared in The Analyst.

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 also are very dynamic in their properties. We used pyrolysis-gas chromatography mass spectrometry (GCMS) to rapidly screen structure information on humic materials. Other analytical techniques such as NMR, Fourier transform infrared, and energy-dispersive x-ray fluorescence allowed us to greatly extend the interpretability of the pyrolisis-GCMS results. A manuscript describing humic surface properties, utilizing all of these techniques and more, has been published in Environmental Science and Technology.

The following activities were accomplished:

• Using pyrolysis-GCMS and two-dimensional (2-D) NMR (Nuclear Overhauser Effect Spectroscopy [NOESY]), we uncovered kinetic and structural interactions of certain biogenic ligands, Cd2+, and soil humic substance (HS) chemical structures that limit the formation of ligand-Cd complexes. We showed that this type of ternary interaction might affect bioavailability of metal ions to plants. This finding is significant because such complexity of interaction is typically assumed not to occur, and changes how we design future studies to understand soil binding of toxic metals.

• Using a combination of a new HS isolation method with several 2-D NMR techniques and pyrolysis-GCMS, we found peptidic side groups to have a mobile nature, although lignin moieties were relatively rigid. This means that the peptidic moieties may be more accessible to water-borne contaminants than the lignoid groups. The development of the combination of these methods illustrates a path to mapping the highly complex HSs in terms of metal bioavailability. This information changes how we design future studies to understand soil binding of toxic metals.

• Under Cd treatment—with or without HSs—phytosiderophores and other exuded metal ion ligands (MIL) were suppressed, yet the uptake of the transition metals Fe, Ni, Cu, Zn, and Mn was enhanced. Thus, we showed that the uptake of contaminant metals is linked with the uptake of nutrient metals. This information has the implications for determining the mechanisms of contaminant uptake in various organisms. Other investigators may use this finding to refine their own research efforts.

• HS interactions with plant metal uptake showed that HSs did not attenuate—and even slightly increased—the accumulation of some transition metals and Cd in roots. HSs also stimulated plant growth, improved MIL production, and alleviated part of the Cd-induced growth inhibition. Thus, we showed that HSs can play multiple roles in toxic metal bioavailability as well as effects. Again, this finding improves the "road map" for further studies of how soils bind toxic metals.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 4 publications 4 publications in selected types All 4 journal articles
Other center views: All 403 publications 290 publications in selected types All 240 journal articles
Type Citation Sub Project Document Sources
Journal Article Fan TW-M, Lane AN, Pedler J, Crowley D, Higashi RM. Comprehensive analysis of organic ligands in whole root exudates using nuclear magnetic resonance and gas chromatography-mass spectrometry. Analytical Biochemistry 1997;251(1):57-68. R825433 (Final)
R825433C007 (Final)
  • Abstract from PubMed
  • Full-text: ScienceDirect-Full Text PDF
  • Abstract: ScienceDirect-Abstract
  • Journal Article Fan TW-M, Higashi RM, Lane AN. Chemical characterization of a chelator-treated soil humate by solution-state multinuclear two-dimensional NMR with FTIR and pyrolysis-GCMS. Environmental Science & Technology 2000;34(9):1636-1646. R825433 (Final)
    R825433C007 (Final)
    R825960 (1999)
    R825960 (2000)
    R825960 (Final)
  • Abstract: ACS-Abstract
  • Journal Article Fan TW-M, Lane AN, Shenker M, Bartley JP, Crowley D, Higashi RM. Comprehensive chemical profiling of gramineous plant root exudates using high-resolution NMR and MS. Photochemistry 2001;57(2):209-221. R825433 (Final)
    R825433C007 (Final)
    R825960 (2001)
    R825960 (Final)
  • Abstract from PubMed
  • Full-text: OSTI-Full Text PDF
  • Abstract: ScienceDirect-Abstract
  • Journal Article Higashi RM, Fan TW-M, Lane AN. Association of desferrioxamine with humic substances and their interaction with cadmium(II) as studied by pyrolysis-gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. Analyst 1998;123(5):911-918. R825433 (Final)
    R825433C007 (Final)
    R825960 (1999)
    R825960 (Final)
  • Abstract: RSC-Abstract
  • Supplemental Keywords:

    ecosystem, ecosystem protection, environmental exposure and risk, geographic area, international cooperation, water, terrestrial ecosystems, aquatic ecosystem, aquatic ecosystem restoration, aquatic ecosystems and estuarine research, biochemistry, ecological effects, ecological indicators, ecological monitoring, ecology and ecosystems, environmental chemistry, restoration, state, water and watershed, watershed, watershed development, watershed land use, watershed management, watershed modeling, watershed restoration, watershed sustainability, agricultural watershed, exploratory research environmental biology, California, CA, Clear Lake, Lake Tahoe, anthropogenic effects, aquatic habitat, biogeochemical cycling, ecological assessment, ecology assessment models, ecosystem monitoring, ecosystem response, ecosystem stress, environmental stress, environmental stress indicators, fish habitat, hydrologic modeling, hydrology, integrated watershed model, lake ecosystems, lakes, land use, nutrient dynamics, nutrient flux, water management options, water quality, wetlands., 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, watershed development, nutrient dynamics, fish habitat, watershed, watershed management, Clear Lake , ecosystem monitoring, agricultural watershed, nutrient flux, anthropogenic effects, Clear Lake, watershed modeling, watershed land use, aquatic habitat, biogeochemcial cycling, ecological assessment, hydrology, lakes, integrated watershed model, aquatic ecosystems, environmental stress, water quality, lake ecosysyems, ecology assessment models, water management options, California (CA), ecosystem stress, Lake Tahoe, hydrologic modeling, environmental stress indicators, land use, watershed restoration

    Relevant Websites: Exit

    Progress and Final Reports:

    Original Abstract
  • 1997
  • 1998
  • 1999

  • 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