azteca: 9.1 and 9.6 ng/g bifenthrin for 10 d and 28 d tests, respectively. Average LC50s were not significantly different in 10 d versus 28 d tests with H. Sediment LC50s were also corrected for organic C content. Median lethal concentrations (LC50s), as well as LC20s and inhibition concentrations (IC20s) were calculated based on measured whole sediment bifenthrin concentrations and interstitial water concentrations. A single range-finder and 2 definitive tests were conducted for each test duration. Criteria are being developed using existing data, along with data from 10 d and 28 d toxicity tests with Hyalella azteca conducted as part of the current study. The Central Valley Regional Water Quality Control Board is developing numeric sediment quality criteria for pyrethroids, beginning with bifenthrin. Many watersheds in the Central Valley region of California are listed as impaired due to pyrethroid-associated sediment toxicity.
0 Comments
Leave a Reply. |