Hydrophysical and Hydrochemical Controls of Cyanobacterial Blooms in Coursey Pond, Delaware (USA).

Noxious cyanobacterial blooms are common in many ponds in the mid-Atlantic Coastal Plain. In Delaware, blooms normally occur between July and October, yet no in-depth analyses of the causes and predictors exist. A study using commercially available, high-frequency, continuous, and automated biogeochemical sensors at Coursey Pond, Delaware, a pond known for perennial summer blooms, was conducted to investigate how hydrophysical and hydrochemical conditions affect bloom dynamics.

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.

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).

Enhanced dissolution of silicate minerals by bacteria at near-neutral pH.

Previous studies have shown that various microorganisms can enhance the dissolution of silicate minerals at low (<5) or high (>8) pH. However, it was not known if they can have an effect at near-neutral pH. Almost half of 17 isolates examined in this study stimulated bytownite dissolution at near-neutral pH while in a resting state in buffered glucose.