科研之友
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摘要
The current study investigated the potential of vegetated drainage ditches for mitigating the impact of agricultural irrigation runoff on downstream aquatic ecosystems Water column toxicity to larval fathead minnow (Pimephales promelas) and the amphipod Hyalella azteca was measured for 12h or less at the ditch inflow and outflow using custom built in situ exposure systems In addition water and sediment samples were subject to standard toxicity tests with Ceriodaphnia dubia and H azteca respectively No acute toxicity to larval fathead minnow was observed however runoff was highly toxic to invertebrates Passage through a 389 to 402 m section of vegetated ditch had a mitigating effect and reduced toxicity to some degree However runoff from an alfalfa field treated with chlorpyrifos remained highly toxic to both invertebrate species and runoff from a tomato field treated with permethrin remained highly toxic to H azteca after passage through the ditch Predicted toxic units calculated from insecticide concentrations in runoff and 96 h median lethal concentration (LC50) values generally agreed with C dubia toxicity measured in the laboratory but significantly underestimated in situ toxicity to H azteca Sediments collected near the ditch outflow were toxic to H azteca Results from the current study demonstrate that experimental vegetated ditches were unable to eliminate the risk of irrigation runoff to aquatic ecosystems In addition protective measures based on chemical co
- 出版日期2010-12
