基于种间关系预测评估稻菜轮作区地表水中吡虫啉的生态风险

Ecological risk assessment of imidacloprid in surface water from ricevegetable rotation areas by using interspecies correlation estimation

吡虫啉(imidacloprid)在我国(亚)热带地表水体中频繁被检出,然而因本土水生生物相关毒理学数据严重缺乏,目前关于其在热带常见作物系统周围水体中生态风险的评估明显不足。本研究基于网络种间关系预测(web-interspecific correlation estimation,Web-ICE)结合物种敏感度分布(species sensitivity distribution,SSD)曲线,通过获取本地水生生物急性毒性风险阈值——5%物种危害质量浓度(HC_(5)),利用风险商值法(risk quotient,RQ),评估了吡虫啉在海南省澄迈县稻菜轮作区地表水中的生态风险。结果表明:海南省澄迈县稻菜轮作区地表水中吡虫啉的HC_(5)值为4.30μg/L,其中有41.7%水样的RQ值高于1,且中位数和最大浓度对应的RQ值明显高于我国其他区域地表水,表明吡虫啉残留对所研究区域地表水中水生生物具有较高的潜在生态风险;在稻菜轮作过程中,4月份作物播种期(92.3%水体RQ>1)、蔬菜种植期(平均RQ=2.53,68%水体RQ>1)和澄迈中部区域水体中的吡虫啉呈现较高的生态风险,表明吡虫啉长期/脉冲输入造成其生态风险具有显著的时空和作物特征,因此需对该农药在该区域稻菜轮作实践中进行分种植期、分区域合理使用和限制使用。

Imidacloprid is widely detected in surface water from sub-tropical or tropical agricultural regions of China.However,there is scanty information on the ecological risk assessment of imidacloprid in surface water near tropical crop systems due to the lack of toxicity data on local aquatic organisms.In this study,the acute toxicity risk threshold-hazardous concentration at the 5^(th) percentile of the species(HC_(5))-of imidacloprid to local aquatic organisms in surface water was obtained based on web-interspecific correlation estimation(Web-ICE)and species sensitivity distribution(SSD)models,then its ecological risk assessment in surface water near rice-vegetable practice in Chengmai(Hainan)was temporally and spatially assessed by risk quotient(RQ).The results showed that the risk threshold HC_(5) of imidacloprid in the aquatic environment around the rice-vegetable rotation in Chengmai is 4.30μg/L,41.7%of water samples with the RQ of higher than 1.Also,the RQ values corresponding to the median and maximum concentrations of imidacloprid in surface water from our study were significantly higher than the RQ values in surface water from other regions of China,indicating that imidacloprid residues had higher potential ecological risks to aquatic organisms in surface water from tropical ricevegetable rotation field.In addition,there was the highest potential ecological risk occurring in April,the sowing time(RQ>1 in 92.3%surface water),vegetable planting period(mean RQ=2.53 with RQ>1 with 68%water surface water),and the central regions of Chengmai during the practice of ricevegetable rotation,indicating that there were significant spatiotemporal and crop-related characteristics of the ecological risk of imidacloprid in surface water.It thus contrives to limit and reasonably use imidacloprid by planting period and region in the practice of rice-vegetable rotation in Chengmai,Hainan.