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USE OF ULVA LACTUCA TO DISTINGUISH PH DEPENDENT TOXICANTS IN MARINE WATERS AND SEDIMENTS
Citation:
Ho, K T., A KuhnHines, M C. Pelletier, R M. Burgess, AND A. Helmstetter. USE OF ULVA LACTUCA TO DISTINGUISH PH DEPENDENT TOXICANTS IN MARINE WATERS AND SEDIMENTS. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 18(2):207-212.
Description:
Ulva lactuca (sea lettuce) is a cosmopolitan marine attached green seaweed capable of sequestering high environmental levels of ammonia. Ammonia can be acutely toxic to marine organisms and is often found in dredged sediments from highly industrial areas or from areas with high carbon inputs. For the purposes of dredged sediment disposal as well as in determining causes of toxicity in complex mixtures, it is important to distinguish ammonia toxicity from the toxicity of other compounds. The use of U. lactuca to selectively remove ammonia from waters and sediments as part of a toxicity identification and evaluation (TIE) procedure was evaluated. Ulva lactuca lowered concentrations of total ammonia from 75 to 17 mg/L in <8h in water-only exposures. This treatment also reduced 48-h amphipod mortality from 75 to 20%. In whole sediments, U. lactuca lowered interstitial water concentrations of ammonia from 60 to 20 mg/L, while keeping overlying water concentrations below detectable limits (<1 mg/L). To determine the limitations of the U. lactuca method to selectively remove ammonia from solution, metal and organic accumulation experiments were performed. U. lactuca generally took up <15% of metals present, with most of the exposures resulting in less than a 10% uptake. In contrast, U. lactuca removed 77% of lindane and 95% of fluoranthene. Results of a TIE conducted on sediments from an industrial marine harbor indicated U. lactuca was useful, in conjunction with other procedures, in categorizing ammonia as a sediment toxicant.