Howe, G. E., Marking, L. L., Bills, T. D., Rach, J. J., and Mayer, F. L. Jr., 1994,
Effects of water temperature and pH on toxicity of terbufos, trichlorfon,
4-nitrophenol and 2,4-dinitrophenol to the amphipod Gammarus pseudolimnaeus
and rainbow trout (Oncorhynchus mykiss): Environmental Toxicology and
Chemistry, v. 13, no. 1, p. 51-66.

Abstract

Acute toxicity tests were conducted to determine (a) the individual and interactive
effects of water temperature (7, 12, 17 degree C), pH (6.5, 7.5, 8.5, 9.5), and time
on the toxicity of terbufos, trichlorfon, 4- nitrophenol, and 2,4-dinitrophenol to
rainbow trout (Oncorhynchus mykiss) and the amphipod Gammarus
pseudolimnaeus, and (b) the individual and interactive effects of water temperature
and pH on chemical bioconcentration during acute tests with rainbow trout and
Gammarus exposed to terbufos, 4-nitrophenol, and 2,4-dinitrophenol. The toxicity
of all four chemicals was significantly affected by pH in all tests, except for
Gammarus exposed to terbufos. The toxicity of terbufos to rainbow trout and
Gammarus was less at pH 7.5 than at higher or lower pH. The toxicity of both
nitrophenols decreased as pH increased, whereas the toxicity of trichlorfon
increased with pH. The effect of pH on trichlorfon toxicity decreased with
temperature. Temperature significantly affected the toxicity of all four chemicals to
both species. Toxicity increased with temperature in all tests, except for rainbow
trout exposed to nitrophenols; toxicity decreased as temperature increased for
rainbow trout. Chemical bioconcentration was also significantly affected by
temperature and pH and was directly related to toxicity in most tests. Significant
interactive effects between toxicity-modifying factors were also frequently
observed. Temperature and pH effects on chemical toxicity need to be considered
in chemical hazard assessment to ensure adequate protection of aquatic organisms.

Keywords

terbufos-, trichlorfon-, p-nitrophenol, 2,4-dinitrophenol, toxicity-, pH-,
water-temperature, Gammarus- pseudolimnaeus, Oncorhynchus-mykiss,
toxicity-testing, toxicity-tests, temperature-effects, pH-effects, bioaccumulation-,
synergism-, pesticides-, phenols-