Abstract
There is limited data concerning the toxicity of ammonia in fresh soft-waters. Ammonia toxicity is largely dependent on pH and temperature. The USEPA have derived equations to adjust species toxicity estimates based on changes in pH and temperature. It has been reported that the pH-ammonia toxicity relationship, derived by the USEPA, may differ in waters with low ionic concentrations due to the absence of potentially ameliorative ionic constituents. The present study aimed to assess the pH-ammonia toxicity relationship for the tropical green hydra, Hydra viridissima, across a range of pH in a natural water with low ionic content.
Ammonia toxicity to H. viridissima was assessed at a pH range between 6.0 and 8.5 and temperature 27.5 ±1°C. Test solution pH was maintained using a pH buffer. The resulting EC50s ranged between 9.62 (7.95-11.65) mg L-1 TAN at pH 6.0 to 0.64 (0.50-0.81) mg L-1 TAN at pH 7.9. The results indicated that increasing pH increased the sensitivity of H. viridissima to ammonia. The pH dependence equation derived by the USEPA accurately described the relationship between pH and ammonia toxicity for H. viridissima. However, when the model parameters for the generic pooled relationship were used, the fit was less accurate (r2 = 0.66), indicating that the generic pooled pH-dependence equations may not be appropriate for use with this species. This article is protected by copyright. All rights reserved
from Enviromental via alkiviadis.1961 on Inoreader http://ift.tt/2DUYd8D
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου