We report results on the first field-scale application of activated carbon (AC) amendment to contaminated sediment for in-situ stabilization of polychlorinated biphenyls (PCBs). The test was performed on a tidal mud flat at South Basin, adjacent to the former Hunters Point Naval Shipyard, San Francisco Bay, CA. The major goals of the field study were to (1) assess scale up of the AC mixing technology using two available, large-scale devices, (2) validate the effectiveness of the AC amendment at the field scale, and (3) identify possible adverse effects of the remediation technology. Also, the test allowed comparison among monitoring tools, evaluation of longer-term effectiveness of AC amendment, and identification of field-related factors that confound the performance of in-situ biological assessments. Following background pretreatment measurements, we successfully incorporated AC into sediment to a nominal 30 cm depth during a single mixing event, as confirmed by total organic carbon and black carbon contents in the designated test plots. The measured AC dose averaged 2.0-3.2 wt% and varied depending on sampling locations and mixing equipment. AC amendment did not impact sediment resuspension or PCB release into the water column over the treatment plots, nor adversely impactthe existing macro benthic community composition, richness, or diversity. The PCB bioaccumulation in marine clams was reduced when exposed to sediment treated with 2% AC in comparison to the control plot Field-deployed semi permeable membrane devices and polyethylene devices showed about 50% reduction in PCB uptake in AC-treated sediment and similar reduction in estimated pore-water PCB concentration. This reduction was evident even after 13-month post-treatment with then 7 months of continuous exposure, indicating AC treatment efficacy was retained for an extended period. Aqueous equilibrium PCB concentrations and PCB desorption showed an AC-dose response. Field-exposed AC after 18 months retained a strong stabilization capability to reduce aqueous equilibrium PCB concentrations by about 90%, which also supports the long-term effectiveness of AC in the field. Additional mixing during or after AC deployment, increasing AC dose, reducing AC-particle size, and sequential deployment of AC dose will likely improve AC-sediment contact and overall effectiveness. The reductions in PCB availability observed with slow mass transfer under field conditions calls for predictive models to assess the long-term trends in pore-water PCB concentrations and the benefits of alternative in-situ AC application and mixing strategies.

No abstract

Surf zone fishes were captured by beach seine over the late summer and early fall of 5 yr (1995 to 1999), spanning pre-, during, and post-nourishment time periods along a 15 km expanse of the New Jersey shoreline. During the baseline years of sampling, silversides (primarily Menidia menidia) numerically dominated the surf-zone fish community. In 1997, coincident with beach nourishment operations, bluefish Pomatomus saltatrix became numerically dominant, increasing in abundance 10-fold. Bluefish were not captured near active beach nourishment sites and were significantly more abundant at reference stations than in the beach nourishment (treatment) area for 2 of 6 sampling dates in 1997. In contrast, northern kingfish Menticirrhus saxatilis were more abundant at treatment stations in 1997, and on one occasion congregated at the stations undergoing active sand replenishment. The feeding habits of Atlantic silversides and northern kingfish were consistent throughout the study period. In 1997, prey biomass was greater in fish caught at treatment stations when significant differences occurred. Prey consisted primarily of benthic invertebrates such as polychaetes and mole crabs. Amphipods and insects, which probably originated from groins and terrestrial sources respectively, were also common prey items and were present in plankton samples. Retrospective power analysis indicates that an approximate 3-fold difference in mean fish abundance was the minimum detectable effect size between reference and treatment areas. Beach nourishment impacts on the surf zone fish monitored in this study were restricted to localized attraction (northern kingfish) and avoidance (bluefish) responses to the beach nourishment operation.

The U.S. Army Engineer Research and Development Center Environmental Laboratory, Vicksburg, MS, conducted a study to determine the extent to which Hurricane Katrina floodwaters in the New Orleans, Louisiana area may have had impacts on wildlife habitat and other biological resources in surrounding areas. These studies were conducted as part of the Interagency Performance Evaluation Taskforce, an investigation of environmental impacts originating from the failure of the hurricane protection system during Hurricane Katrina. This paper presents data regarding the effects of pumped floodwaters on sediment chemistry, toxicity, and benthic invertebrate assemblages near pumping stations that discharged floodwaters into marshes near Chalmette and Violet, Louisiana. Chemical contamination of sediments was observed and varied among sample locations (e.g., outfall locations, wastewater treatment plant, canals, and wetlands); however, trends in the chemistry data were not always consistent with bioassay results. A comparison of the sediment chemistry data from this study with three other studies reporting concentrations of chemicals in sediments within the city of New Orleans suggested that sediments and associated contaminants present within the levees were not pumped into the marsh in appreciable quantities.