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|Title:||Risk of pore water ammonia toxicity in dredged material bioassays|
|Authors:||Dredging Operations Technical Support Program (U.S.)|
Sims, Jerre G.
Moore, David W.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: Generally, ammonia is not treated as a contaminant of concern in the regulatory evaluation of dredged material since it undergoes rapid oxidation and dilution during dredging and disposal. However, because dredged material is evaluated using effects-based testing (i.e., whole sediment and elutriate toxicity tests), there is the potential for ammonia to exert toxicity and confound the regulatory decision-making process. To evaluate the potential for ammonia toxicity in dredged material bioassays, a literature review and survey of U.S. Army Corps of Engineers Divisions and Districts was conducted. Data included reported environmental pore water exposure concentrations of ammonia and effects concentrations shown to cause toxicity in laboratory studies with aquatic species. The majority of reported effect concentrations (>45 and >25 percent fish and invertebrates, respectively) were <40 μM NH3/l; environmental pore water concentrations were >40 μM/l (10-percent exposure concentrations and 30-percent dredged material exposure concentrations). This comparison of reported exposure and effects concentrations suggests that a risk of pore water toxicity in dredged material bioassays may be significant. However, a number of biases in this limited data set are discussed that must be considered before any definitive conclusions can be drawn.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|