巢湖圩区渍水对溞活动、生殖抑制作用及其与氮磷质量浓度关系

Inhibitive effect of waterlogging on Daphnia mobility and fertility in a polder of Chaohu Lake and its correlation with nitrogen and phosphorus concentrations

文章以大型溞(Daphnia magna,DP)和老年低额溞(Simocephalus vetulus,SP)为对象,对2020年7月至2021年3月取自庐江同大圩的221个田间、沟渠和排灌站水样进行溞活动和生殖抑制检测,分析溞抑制率与水样氮、磷质量浓度之间的关系。结果显示:引起溞24、48 h急性活动抑制的水样总氮(total nitrogen,TN)质量浓度一般大于10 mg/L,总磷(total phosphorus,TP)质量浓度大于0.1 mg/L;24 h内引起溞50%以上活动抑制率的水样TN、TP平均质量浓度分别达40、0.6 mg/L以上;抑制水样数量占比及平均抑制率均为田间最高,沟渠次之,排灌站最低,与氮、磷质量浓度沿程降低一致;稀释可减轻急性抑制程度,但部分水样即使充分稀释至不再有急性抑制作用的质量浓度水平仍然对溞产生生殖干扰,表现为TN质量浓度越高,溞生殖量越低;过滤可削减水中悬浮颗粒和氮磷质量浓度,并减轻对溞的毒性作用。

A total of 221 water samples were taken during July 2020 and March 2021,from fields,ditches,and drainage pump stations of Tongdawei Polder,Lujiang County near Chaohu Lake.Nitrogen and phosphorus concentrations of these samples and their inhibition on the mobility and fertility of the water flea Daphnia magna(DP)and Simocephalus vetulus(SP)were tested.It was shown that the total nitrogen(TN)concentrations in water samples that caused daphnids acute mobility inhibition at 24 and 48 h were generally above 10 mg/L,and total phosphorus(TP)concentrations above 0.1 mg/L.The average concentrations of TN and TP in water samples that caused a mobility inhibition rate over 50%within 24 h reached more than 40 and 0.6 mg/L,respectively.In agreement with the decreasing of nitrogen and phosphorus concentrations from fields to ditches to drainage pump stations,the percentage of inhibitory samples and the average inhibition rates of water from fields were the highest,followed by ditches and drainage pump stations.Dilution alleviated the acute inhibitive effect,but some samples remained to interfere the fertility of daphnids even after being diluted to the level causing no acute mobility inhibition.It seemed that the higher the TN concentration,the more severely the fertility was inhibited.Filtration removed suspension particles from water,thus reducing the concentrations of TN and TP and alleviating the toxic effect on daphnids.