Skip to main content
Advanced Search

Filters: Tags: Metals (X) > partyWithName: Michelle I Hornberger (X)

4 results (22ms)   

View Results as: JSON ATOM CSV
thumbnail
Long-term monitoring of stream-bed sediments reveals spatial and temporal trends in metal concentrations. Here we use concentration gradient “heat maps” as a visualization tool to report annual mean arsenic, cadmium and copper concentrations along a contamination gradient in the Clark Fork River (CFR) in Western Montana. The CFR has been heavily impacted by large-scale mining operations since the 19th century. Legacy mine waste and tailings have been deposited within the streambed, banks, and floodplains more than 200 kilometers downstream. Sieved sediment samples (<63µm) have been collected at 10 stations along a 200 kilometer contamination gradient annually since 1996. Ongoing remediation activities in the upper...
thumbnail
Surface sediment samples from the North San Francisco Bay-Delta Estuary were collected monthly at five stations located west of Rio Vista and east of Point Pinole. Sediment was collected near Montezuma Slough, Chips Island, the Concord Naval Weapons Station, Carquinez Strait near Martinez, and San Pablo Bay at water depths ranging from 6.5 to 14.3 meters. Samples were collected coincident with water-quality measurements (Cloern and Schraga, 2016) and metal concentrations in filter-feeding bivalves (Brown and Luoma, 1995; Stewart et al., 2013). Depending on the station, the period of record ranges from 13 to 24 years, from December 1993 to September 2017. Samples were sieved to <64 µm to eliminate grain-size bias...
thumbnail
Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the form of metal-enriched particulate matter or seston, comprising a mixture of organic and inorganic materials (J.N. Moore and S.N. Luoma, Hazardous wastes from large-scale metal extraction: A case study. Environmental Science and Technology, v.24:1278-1285, 1990). Metal enriched seston poses a dietary exposure risk to filter-feeding...
My primary research objective is to evaluate ecosystem health in freshwater systems using biologically meaningful measures of metal exposure. Resident aquatic organisms accumulate metal into their tissue by integrating the metal from their environment (dissolved and diet). Using physiological parameters derived from earlier experiments, I am developing a model to predict biomonitor tissue concentrations under various exposure conditions. The goal of this research is to link biological responses to changes in environmental condition (e.g., remediation and physical disturbances associated with floods). While this work was developed from the Clark Fork River study, the model is applicable to other impaired rivers and...
    map background search result map search result map Metal Concentrations of Sediment from 1993-2017 in San Francisco Bay-Delta Estuary (San Pablo Bay and Suisun Bay), CA Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020 Metal concentrations in seston and water in the Clark Fork River, MT Metal Concentrations of Sediment from 1993-2017 in San Francisco Bay-Delta Estuary (San Pablo Bay and Suisun Bay), CA Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020 Metal concentrations in seston and water in the Clark Fork River, MT