Dw. Sved et Mh. Roberts, A NOVEL USE FOR THE CONTINUOUS-FLOW SERIAL DILUTER - AQUATIC TOXICITYTESTING OF CONTAMINATED SEDIMENTS IN SUSPENSION, Water research, 29(4), 1995, pp. 1169-1177
Testing the toxicity of contaminated sediments is crucial to evaluatin
g environmental risks because hydrophobic chemicals readily sorb to pa
rticulate matter. The 96-h median lethal concentration (96-h LC(50)) f
or creosote-contaminated sediments was determined with spot (Leiostomu
s xanthurus), a saltwater fish common to estuarine areas of the easter
n United States. Fish were exposed to suspended sediment in a flow-thr
ough system. A continuous-flow serial diluter was used to produce five
concentrations of creosote. Sediment without creosote added was used
to maintain a constant sediment concentration throughout the dilution
process and for a vehicle control. The nominal concentration of suspen
ded sediment in all treatments was 20 mg/l, on a dry-weight basis. Mea
n total resolvable polycyclic aromatic hydrocarbon (PAH) concentration
s tested were 110, 250, 560, 1400, and 3300 mu g PAH/l. Sediment conce
ntration varied <24% and PAH concentration varied <36%. The 96-h LC(50
) was 1740 mu g PAH/l (95% confidence interval = 1480-2060 mu g PAH/l)
. This result compares favorably with results from tests using other s
pecies of fish and exposure methods. Other reported methods, however,
have not demonstrated the constancy or ease of dosage administration f
or a range of concentrations as the system used here. Exposing fish to
suspended sediments contaminated with hydrophobic compounds may be an
appropriate method for assessing the environmental risk of hydrophobi
c chemicals to fish.