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aoe is difficult to determine in che natural environment, but is 
! igportent in detarmining toxicity. Trace metals present in dredged material 
zy follow many pathways waen introduced to the site environment; ‘for 
csstamce, the trace metals cm: (1) be released into the water while the 
tredged material is settling or after deposition ou the sea floor, (2) temain 
wigorded to site sedizents, end/or (3) be ingested, primarily by benthic 
grgzpisms. 
Laboratory and field tests on dredged material indicate that, under 
certain conditions (e.g., oxidizing or reducing envirommeats), some trace 
netels are released from dredged material into seawater in concentrations 
well above background levels (Lee et al., 1975). Manganese was released in 
the greatest quantities under both oxidizing and reducing conditions. 
Under ceducing conditions, substantial amounts of iron and le2d were 
released. Zinc was taken up from water under both oxidizing and reducing 
conditions, while copper, lead, and cadmium were neither released nor taken 
up under oxidizing conditions. Actual increases over backsround values 
which did occur were insignificant (parts per billion or less), so that 
considerable analytical difficulties are encountered in even defecting the 
contaminants. Furthermore, there is little evidence to indicate that such 
low levels would cause adverse effects on marine organisms during the 
extremely short time before the concentrations were diluted to the original 
dackground levels (Pequegnat et al., 1978b). 
Some test organisms have accumulated PCB's or DDT from some dredged 
Material. However, field studies at the Mud Dump have noc conclusively shown 
higher levels of PCB or DDT accumulation in organisms (Appendi= 3). Pequegnat 
et al. (1980b) reported that concentrations of organochlorine residues in 
Organisms showed little corzelation to the presence of the respective 
Contaminant in the sediments. Organisms from the control ezea (uncontaminated 
Sediments) had contaminant levels comparable to organisms from the dump site ~ 
(contaminated sediments). This problem is cursently under investigation; West 
and Batcher (1980) indicared that most PCB's in the Apex were derived from the 
dimping of sewage sludge. 
