Chesapeake Bay benthic community restoration goals

Benthic macroinvertebrate assemblages have been an integral part of the Chesapeake Bay monitoring program since its inception due to their ecological importance and their value as biological indicators. The condition of benthic assemblages reflects an integration of temporally variable environmental conditions and the effects of multiple types of environmental stresses. As such, benthic assemblages provide a useful complement to more temporally variable chemical and water quality monitoring measures. While assessments using benthic monitoring data have been useful for characterizing changes in environmental conditions at individual sites over time, and for relating the condition of sites to pollution loadings and sources, the full potential of these assessments for addressing larger management questions, such as "What is the overall condition of the Bay?" or "How does the condition of various tributaries compare?" has not yet been realized. Regional-scale assessments of ecological status and trends using benthic assemblages are limited by the fact that benthic assemblages are strongly influenced by naturally varying habitat elements, such as salinity, sediment type, and depth. Such natural variability confounds interpretation of differences in the benthic community differences as simple responses to anthropogenic environmental perturbations. An additional limitation is that different sampling methodologies used in various programs often constrain the extent to which the benthic data can be integrated for a unified assessment. The objective of this project was to develop a practical and conceptually sound framework for assessing benthic environmental conditions in Chesapeake Bay that would address the general constraints and limitations just described. This was accomplished by standardizing benthic data from several different monitoring programs to allow their integration into a single, coherent data base. From that data base a set of measures (Chesapeake Bay Benthic Restoration Goals) was developed to describe characteristics of benthic assemblages expected at sites having little evidence of environmental stress or disturbance. Using these goals, benthic data from any part of the Bay could be compared to determine whether conditions at that site met, were above, or were below expectations defined for reference sites in similar habitats.Virginia Institute of Marine Scienc

Screening Level Assessment of Risks Due to Dioxin Emissions from Burning Oil from the BP Deepwater Horizon Gulf of Mexico Spill

Between April 28 and July 19 of 2010, the U.S. Coast Guard conducted in situ oil burns as one approach used for the management of oil spilled after the explosion and subsequent sinking of the BP Deepwater Horizon platform in the Gulf of Mexico. The purpose of this paper is to describe a screening level assessment of the exposures and risks posed by the dioxin emissions from these fires. Using upper estimates for the oil burn emission factor, modeled air and fish concentrations, and conservative exposure assumptions, the potential cancer risk was estimated for three scenarios: inhalation exposure to workers, inhalation exposure to residents on the mainland, and fish ingestion exposures to residents. U.S. EPA’s AERMOD model was used to estimate air concentrations in the immediate vicinity of the oil burns and NOAA’s HYSPLIT model was used to estimate more distant air concentrations and deposition rates. The lifetime incremental cancer risks were estimated as 6 × 10−8 for inhalation by workers, 6 × 10−12 for inhalation by onshore residents, and 6 × 10−8 for fish consumption by residents. For all scenarios, the risk estimates represent upper bounds and actual risks would be expected to be less

Screening Level Assessment of Risks Due to Dioxin Emissions from Burning Oil from the BP Deepwater Horizon Gulf of Mexico Spill

Between April 28 and July 19 of 2010, the U.S. Coast Guard conducted in situ oil burns as one approach used for the management of oil spilled after the explosion and subsequent sinking of the BP Deepwater Horizon platform in the Gulf of Mexico. The purpose of this paper is to describe a screening level assessment of the exposures and risks posed by the dioxin emissions from these fires. Using upper estimates for the oil burn emission factor, modeled air and fish concentrations, and conservative exposure assumptions, the potential cancer risk was estimated for three scenarios: inhalation exposure to workers, inhalation exposure to residents on the mainland, and fish ingestion exposures to residents. U.S. EPA’s AERMOD model was used to estimate air concentrations in the immediate vicinity of the oil burns and NOAA’s HYSPLIT model was used to estimate more distant air concentrations and deposition rates. The lifetime incremental cancer risks were estimated as 6 × 10−8 for inhalation by workers, 6 × 10−12 for inhalation by onshore residents, and 6 × 10−8 for fish consumption by residents. For all scenarios, the risk estimates represent upper bounds and actual risks would be expected to be less