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- An evaluation of methods for calculating mean sediment quality guildline quotients as indicators of contamination and acute toxicity to amphipods by chemical mixtures
- Mean sediment quality guideline quotients (mean SQGQs) were developed to represent the presence of chemical mixtures in sediments and are derived by normalizing a suite of chemicals to their respective numerical sediment quality guidelines (SQGs). Mean SQGQs incorporate the number of SQGs exceeded and the degree to which they are exceeded and are used for comparison with observed biological effects in the laboratory or field. The current research makes it clear, however, that the number and type of SQGs used in the derivation of these mean quotients can influence the ability of mean SQGQ values to correctly predict acute toxicity to marine amphipods in laboratory toxicity tests. To determine the optimal predictive ability of mean SQGQs, a total of 18 different chemical combinations were developed and compared. The ability of each set of mean SQGQs to correctly predict the presence and absence of acute toxicity to amphipods was determined using three independent databases (n = 605, 2753, 226). Calculated mean SQGQ values for all chemical combinations ranged from 0.002 to 100. The mean SQGQ that was most predictive of acute toxicity to amphipods is calculated as SQGQ1 = ((∑ ([cadmium]/4.21)([copper]/270)([lead]/112.18)([silver]/1.77)([zinc]/ 410)([total chlordane]/6)([dieldrin]/8)([total PAHOC]/1,800)([total PCB]/400))/9). Both the incidence and magnitude of acute toxicity to amphipods increased with increasing SQGQ1 values. To provide better comparability between regions and national surveys, SQGQ1 is recommended to serve as the standard method for combination of chemicals and respective SQGs when calculating mean SQGQs.
- Fairey, Long, Roberts, Anderson, Phillips, Hunt, Puckett, Wilson
- Validation of a short-term toxicity test endpoint by comparison with longer-term effects on larval red abalone Haliotis rufescens,
- Experiments were conducted to compare a short-term 48-h aquatic toxicity test endpoint of abnormal larval shell development with other, more clearly adverse effects. In similar experiments conducted with two different toxicants, zinc sulfate and bleached-kraft mill effluent, red abalone (Haliotis rufescens) embryos were simultaneously exposed to identical dilution series and incubated for three different exposure periods: 48 h, 48 h followed by an 8-d recovery period in clean seawater, and 10 d of continuous exposure. Abnormal larval shell development was assessed in the 48-h short-term tests, and inhibition of metamorphosis was assessed in the exposure-recovery and continuous exposure experiments. For the zinc experiments, the median effective concentration (EC50) values for the 48-h exposure the exposure-recovery experiment, and the continuous exposure experiment were 40, 34, and 32 μg/L zinc, respectively. For the bleached- kraft mill effluent experiments, the EC50 values were 0.98, 0.76, and 0.69% effluent, respectively. Results indicate that toxicant concentrations causing abnormal larval shell development also inhibit metamorphosis and that larvae exposed to toxicant concentrations which inhibit larval shell development do not recover to metamorphose when transferred to clean seawater. None of the successfully metamorphosed postlarvae had deformed larval shells, indicating that shell deformity precludes survival past the planktonic stage. A longer (15-d) experiment allowed measurement of postlarval shell length in exposed postmetamorphic abalone. Insignificant differences in postlarval shell length indicated that the timing of larval metamorphosis was similar regardless of toxicant exposure and that the effects of the toxicant was to inhibit rather than to delay metamorphosis., Cited By (since 1996):27, CODEN: ETOCD, ,
- Conroy, Hunt, Anderson