Soil Core Microcosm - A Potential Screening Tool

摘要

The report presents the results of two experiments performed at CERL in an effort to determine the suitability of a soil core microcosm as a screening tool under FIFRA. The soil core microcosm consisted of a 5 x 10 cm soil core removed intact from a field site and encased in PVC. In Experiment I, 0.25 lb/ac applications of 14C-labeled dieldrin, methyl parathion and 2,4,5-T were examined, whereas 0.25, 0.50 and 1.0 lb/a applications of HCB were studied in Experiment II. Weekly leachates were analyzed for NO3-1, PO4-1, NH3, Ca+2 and DOC as well as 14C. The majority of the chemicals from both experiments found in the soil were in the top 2 cm. Extractable metabolites were detected for all but HCB. 2,4,5-T had practically no effect on any nutrient losses. NO3-1 loss was impacted by dieldrin and methyl parathion. PO4-3 was impacted by methyl parathion, 0.5 lb/a HCB and 1.0 lb/a HCB. NH3 was impacted by the two upper levels of HCB. Calcium export was altered by methyl parathion and dieldrin. DOC was significantly impacted by methyl parathion and 1.0 lb/a HCB. Treatment levels for all chemicals were below normal application rates and did not really challenge the system. It is possible to gain some assessment of chemical effect on a soil ecosystem, its fate and metabolism with the soil core microcosms.