Impact/Purpose:

The objective of this task is to addres the risk management LTG for the Contaminated Sites Research Program in the area of contaminated sediments. The contaminated sediments LTGs of "How can we better assess and document the short- and long-term effectiveness of remediation approaches (e.g., dredging vs capping vs monitored natural attenuation (MNA)?" and "How can any short-term negative impacts from the use of one of these options be reduced?" are partially addressed under this task. The research areas in this task includes: the miniturization of sediment toxicity tests & elutriate comparability with whole sediment assays; and bioassays, development and demonstration of ecological tools for sediment monitoring to assess toxicity, gene expression ecological impacts and the use of stable isotope analysis, to develop a mechanistic understanding of energy and material flux within PCB contaminated streams and lakes and their food webs. Stable isotopes techniques will be used to track biomagnification of PCBs and other persistent bioaccumulative contaminants in lake food and stream food webs using a site based approach in collaboration with other ORD labs' contaminanted sediment research.

Description:

Contaminated sediments are of interest to a broad group of programs in the agency. OERR and the Regions are interested in monitoring contaminated sediments to characterize/assess existing conditions, determine remediation alternatives, track spatial and temporal changes, and determine if post-remediation goals have been achieved. The Office of Water, Regions, and states are interested in contaminated sediments because they impact designated uses established in State water quality standards. Office of Science and Technology (OST) is interested in contaminated sediments because they have been given a charge to conduct a comprehensive national data survey regarding the quality of aquatic sediments in the United States. In response to the Water Resources Development Act of 1992, OST has evaluated sediment chemistry, tissue chemistry, and sediment toxicity data from 1983-1999, taken at the same sampling station (or site), individually and in combination using a variety of assessment methods. Because of these varied needs, a consistent approach to monitoring the chemical, physical, and biological characteristics/conditions of contaminated sediments across all of EPA's programs would be advantageous. To address the chemical, physical, and biological monitoring issues associated with contaminated sediments, collaborative efforts will be sought across ORD labs and Regions to work on sites where multiple issues can be addressed simultaneously. Various approaches, methods, and techniques can be tested in a common contaminated environment, maximizing the efficiency and comparability among the results of the proposed activities. For example, NERL, NRMRL and NHEERL have proposed to use a site based approach (e.g., Lake Hartwell) to develop and demonstrate various remote sensing and ecological tools and approaches. NERL/EERD research has focused on the use of small short-lived fish as indicators of pre- and post-remediation to determine if changes can be detected sooner in these fish than in longer-lived game or bottom dwelling fish. This research will provide OERR and OW with a valuable tool to rapidly determine the effectiveness of remedial clean up operations without having to wait to observe the effects in longer-lived or bottom dwelling fishes. Also, research will be conducted to assess the effectiveness of remediation operations by conducting pre- and post-remediation toxicity assessments, bioassessments (periphyton, macroinvertebrates and fish monitoring), and toxicogenomics assessments. Included in this proposed research effort will be the development of molecular biological methods to provide new data on the bioavailability, fate and transport of contaminants in sediments. These methods will use several water column and sediment organisms to monitor the real-time bioavailability of these contaminants and their movement between compartments. New and unique data would be integrated into the aquatic components of existing aquatic ecosystem compartmental models (NERL-RTP) to assist in the characterization of the mass balance of sediment contaminants at a collaborative ORD contaminated sediments field study site (e.g., Lake Hartwell). We propose to use an emerging tool in stream ecology, stable isotope analysis, to develop a mechanistic understanding of energy and material flux within PCB contaminated streams and lakes and their food webs. Stable isotopes techniques have been used to track biomagnification of PCBs in marine and lake food webs but similar applications in streams have not been explored. We also hypothesize that PCBs cycling in littoral (i.e., near-shore) and pelagic (i.e., open water) food webs of PCB contaminated sites may delay natural recovery. An analysis of food web dynamics and biomagnification pathways would improve our ability to forecast recovery and interpret current data on PCB levels in fishes of concern. We propose to evaluate new and existing data sets for parameterizing a food web model of Lake Hartwell. Other ecological tools will be assessed for their ability to monitor real-time bioavailability of contaminants as they partition across media.

Record Details:

Record Type:PROJECT

Start Date:10/01/2004

Projected Completion Date:09/01/2008

OMB Category:Other

Record ID: 155271

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Project Information:

Progress :Considering the disconnect between PCB sediment concentrations and fish tissue levels, research was initiated by NRMRL and NERL in 2002 to evaluate the fate and transport of PCBs within the Lake Hartwell ecosystem. Physical, chemical, and biological monitoring included PCB sampling of surficial sediments, the water column, indigenous invertebrates, indigenous phytoplankton, indigenous fish, caged fish, caged clams, semipermeable membrane devices, and PCB flux from the sediment to the water column and from the water column to the atmosphere. We are also conducting a longitudinal study of 12 Mile Creek to determine residual PCB concentrations in organic matter and stream fauna. We are using an emerging tool in stream ecology, stable isotope analysis, to develop a mechanistic understanding of energy and material flux within 12 Mile Creek and its food web.

The purpose of biological monitoring research in Lake Hartwell is to evaluate the biological component of the system, in addition to the chemical monitoring, to detect changes indicative of remedy performance, restoration and recovery. The difficulty of acquiring statistically significant evidence of ecological receptor recovery is at the heart of many of the debates among industry, regulators, communities, and environmental activists. NRC 2000 details the weak monitoring data that are available for remedy selection, remedy performance, and the arguments that are presented as evidence for and against the success of cleanups that have been completed.

2001 Findings.

Sediment samples collected from Site O were not toxic to amphipods but were toxic to FHM embryo/larvae. No significant gene expression was found in the water or sediments collected from Lake Hartwell.

2002 Results

The FHM embryo-larval test with the elutriate samples prepared from the Lake Hartwell sediment samples were successful with survival in the control, Survival was only 65% in the elutriate sample prepared from the background sediment sample. This survival was determined to be statistically different from that of the control, with a pvalue of 0.04. These results were generated using a t-test, alpha = 0.05. All live fry from each replicate were collected at the end of the test and preserved in RNALater buffer.

The H. azteca test with the Lake Hartwell sediment samples was successful with control survival (95%) exceeding the minimum control survival criteria of 90% . Survival in the 5 sediment samples ranged from 80% to 100%. None of the samples were found to be toxic for survival, based on a t-test, alpha = 0.05. Growth of the animals in all 5 sediment samples exceeded the growth of the animals in the control sample..

Fathead minnows results thusfar, show a surprising amount of PCBs accumulated in tissues in the short time frame they were exposed at the 3 sites. At medium and high contaminanted sites at Lake Hartwell, tissue levels in two weeks were at or above the FDA action level of 2 ppm and almost 10 times the wildlife value of 0.18 ppm (Lazorchak et. al. 2003) for exposures of fish eating mammals i.e. Otters and 2 to 3 times higher (0.44 ppm) for fish eating birds, kingfishers. Forage fish, spotfin and shad also show some high levels of PCBs and indicate potential risks to wildlife for fish eating birds and mammals. Results thus far are promising enough in meeting our objective of finding biological indicators to assess whether the biota are responding to the reduction in PCB concentrations in surface sediments and water, and are the tissue levels approaching acceptable levels for wildlife or for human consumption?

2003-2004 Results

Preliminary analysis of stream PCB and stable isotope data indicate that PCB contamination in prevalent throughout the Twelvemile Cr. and Town Cr. mainstems. Contamination was relatively high across media (eg sediment, particulate organic matter, and fish tissue) and trophic levels. The stable isotope

Project IDs:

ID Code :19120

Project type :OMIS