A COMPARISON OF NUTRIENT CONCENTRATIONS AND WATER QUALITY BETWEEN DELAWARE INLAND BAYS AND THE CHESAPEAKE BAY

Deep and wide holes that occur in the Delaware inland bays are a result of subaqueous mud removal, which was used for development in the 1960s. These holes are eighteen feet deep, which create anoxic conditions that are similar to anoxic conditions within deep channels in the Chesapeake Bay. Runoff from adjacent residences, farms, and golf courses causes a large input of nutrients into the Delaware Inland Bay, a mixed estuary water system. Large amounts of nitrogen species, such as nitrate, consumed by phytoplankton growth and multiplication create harmful algal blooms. Hydrogen sulfide is released as a byproduct of the decomposition of organic matter by bacteria in bottom waters. Anoxic conditions can be produced in both the Delaware Inland Bays and the Chesapeake Bay because of the influx of nutrients into these bays. The Chesapeake Bay had higher concentrations of nutrients (10-70µM) due to a larger watershed than the inland bays (5-15µM). In addition, the overwhelming nitrate uptake by phytoplankton may have an impact, such as the decreasing inland bay nitrate concentrations. The Chesapeake Bay has a unique three water mass characterization, with the middle oxic/suboxic interface (10-16 meters) having the highest amounts of nutrients (40-70µM). Within the inland bays, only two main bodies of water exist: the oxic and anoxic zones separated between 2-3 meter depths. The deep hole located in the restricted inland bay of Torquay Canal had high concentrations of hydrogen sulfide (100-200µM). As the summer progressed, surface nitrate decreased from 14µM to <1µM as bottom ammonium ion concentrations increased from 4µM to 16µM. Eliminating the holes by filling them in with naturally dredged sediment will decrease future anoxic conditions by anthropogenic effects within the inland bays and guard against fish kills.