Environmental factors affecting the levels of legacy pesticides in the airshed of Delaware and Chesapeake Bays, USA.

Organochlorine insecticides and their degradation products contribute to toxicity in Chesapeake Bay, USA, sediments and affect the reproductive health of avian species in the region; however, little is known of atmospheric sources or temporal trends in concentrations of these chemicals. Weekly air (n = 265) and daily rain samples (n = 494) were collected over 2000 to 2003 from three locations in the Delmarva Peninsula, USA. Pesticides were consistently present in the gas phase with infrequent detection in the particle phase.

Nitrogen loads through baseflow, stormflow, and underflow to Rehoboth Bay, Delaware.

A detailed study of water and nitrogen (N) discharge from a small, representative subwatershed of Rehoboth Bay, Delaware, was conducted to determine total N loads to the bay. The concentrations of ammonium (NH4(+)), nitrate + nitrite (NO3(-) + NO2(-)), and dissolved and particulate organic N were determined in baseflow and storm waters discharging from Bundicks Branch from October 1998 to April 2002. A novel hydrographic separation model that accounts for significant decreases in baseflow during storm events was developed to estimate N loads during unsampled storms.

Spray irrigation of treated municipal wastewater as a potential source of atmospheric PBDEs.

Spray irrigation facilities utilizing treated municipal wastewater are a potential source of polybrominated diphenyl ethers (PBDEs) to the atmosphere. PBDEs are used as flame retardants in many household items and have been found in wastewaters and biosolids. Evidence of PBDE release from spray irrigation facilities was discovered during a multiyear project to measure semivolatile organic chemical concentrations in air.

Atmospheric nitrogen inputs to the Delaware Inland Bays: the role of ammonia.

A previous assessment of nitrogen loading to the Delaware Inland Bays indicates that atmospheric deposition provides 15-25% of the total, annual N input to these estuaries. A large and increasing fraction of the atmospheric wet flux is NH(4)(+), which for most aquatic organisms represents the most readily assimilated form of this nutrient. Particularly noteworthy is a 60% increase in the precipitation NH(4)(+) concentration at Lewes, DE over the past 20 years, which parallels the increase in poultry production on the Delmarva Peninsula over this period (currently standing at nearly 585 million birds annually).

Characterization of atmospheric ammonia emissions from a commercial chicken house on the Delmarva Peninsula.

A three-dimensional sampling grid using passive collectors was used to characterize the downwind gas-phase ammonia plumes originating from a commercial chicken house on the Delmarva Peninsula in the Chesapeake Bay watershed. Inverse Gaussian plume modeling was used to determine the source strength of the chicken house and the corresponding chicken emission factors. A total of seven field deployments were performed during two different flocks with a sampling duration ranging from 6 to 12.