water column. In contrast to the above cited studies, some recent studies, 

 not dealing specifically with the discharge of dredged material, indicate 

 that contaminants are more bioavailable than previously thought (Halter 

 and Johnson 1977, and statements by Lynn A. Greenwalt; Director of the FWS; 

 Harry M. Ohlendorf, Assistant Director of the Patuxent Wildlife Research 

 Center, FWS; and Foster L. Mayer, Jr., Chief Biologist, Biology Section, 

 Columbia National Fisheries Research Laboratory, FWS, before the U.S. House 

 of Representatives Committee on Merchant Marine and Fisheries, on Problems 

 with Dredge Disposal from New York Harbor 14 March, 20 May, and 21 May, 1980, 

 respectively). In a laboratory study, yellow perch rapidly accumulated PCB's, 

 mercury, selenium, and zinc from resuspended sediments collected from Saginaw 

 Bay, Lake Huron (J.G. Seelye, R.J. Hesselberg, and M.J. Mac, unpublished manu- 

 script. Great Lakes Fishery Laboratory, FWS). 



We believe that much work needs to be completed before the complex 

 dynamics of contaminant availability and movement within the ecosystem is 

 understood. 



Most potential toxicants are sorbed or bound to fine-grained sediments 

 and thus tend to remain with the dredged material. None of the potential 

 contaminants previously mentioned (i.e., ammonia, manganese, and iron) should 

 cause acute water column impacts under normal dilution and mixing conditions. 

 However, hydrogen sulfide is sometimes released from sediments and is highly 

 toxic to aquatic organisms, even with substantial dilution. Hydrogen sulfide 

 may be present in highly organic sediments that contain wood pulp fibers, such 

 as occur in the Pacific Northwest (Serviz et al . 1969). 



Chen et al . (1976) stated that "concerns regarding the release of a 

 significant quantity of toxic materials into solution during dredging opera- 

 tions and disposal are unfounded. Some metals are released in the parts per 

 billion range but others, with the exceptions of manganese and iron, show 

 essentially no release pattern." The work done by Hoss et al . (1974) does 

 indicate that larval fishes could be killed in situations where dilution is 

 not substantial. Chen et al . (1976) also noted that clay, silt, and organic 

 particles, temporarily suspended in the water column, will contain trace 

 metals and hydrocarbons. 



Emphasis is shifting to bioassessment techniques to determine long-term 

 impacts of dredged material on aquatic life (Schuba et al . 1978). Tests 

 should be conducted utilizing sublethal parameters as much as possible. Enzyme 

 induction tests, physiological dysfunction, and pathological and biochemical 

 changes have been useful in documenting cause and effect relationships of 

 contaminants (personal conversation 12 March 1980 with Charles R. Walker, 

 Fishery Ecology Research, FWS, Washington, D.C.). These types of tests are 

 difficult to perform in practical field applications but should be considered 

 as a desirable goal . 



A specialized type of disposal that has limited application for directing 

 toxicants away from critical areas consists of discharging into a strong cur- 

 rent which carries away the dredged material. Disposal can be into a nearby 

 channel or into the mouth of an outlet to the sea, utilizing outgoing tides. 

 Limited use of this technique has not resulted in noticeable adverse environ- 

 mental impacts (telephone conversation 5 February 1979 with Braxton Kaiser, 



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