农村沟渠水体的磷污染水平对底泥磷释放规律的影响研究

Effect of water phosphorus pollution level on phosphorus release from sediment in rural ditch

为揭示农村生活污水排放导致沟渠底泥磷形态转化对农村生态环境的影响,用K 2 HPO 4配置不同水平磷污染水体(TP质量浓度分别为0、5、10、20 mg/L),考察在静态及扰动试验中底泥磷的转化规律。结果表明:(1)当水体TP为0 mg/L,底泥为磷源,逐步向水体释放磷;随水体TP增大,底泥为磷汇,吸附水体中的磷,水体扰动会促进底泥对水体磷的吸附。(2)底泥TP含量随水体TP的升高而增加,扰动试验中底泥TP含量高于静态试验;水体TP为20 mg/L时,扰动试验底泥存在中度污染情况,其余均为轻度污染;底泥TP超出多数底栖动物的耐受含量,对沟渠底栖动物具有较低生态风险。(3)底泥对水体磷的吸附均为物理吸附,扰动试验中底泥4种形态无机磷含量的总和高于静态试验,且底泥磷活性更高,水体扰动将增加底泥对水体的生态风险。

In order to reveal the effect of phosphorus form transformation in ditch sediment caused by rural domestic sewage discharge on rural ecological environment,different concentrations of phosphorus polluted water bodies were prepared by K 2HPO 4(TP mass concentration was 0,5,10,20 mg/L respectively),and the regulation of phosphorus transformation in sediment was investigated in static and disturbance test separately.The results showed that:(1)when water TP was 0 mg/L,the sediment gradually released phosphorus into the water.With the increase of TP,the sediment adsorbed phosphorus,and the water disturbance would promote the phosphorus adsorption of sediment from water.(2)The sediment TP content increased with the increase of water TP,and the sediment TP content in the disturbance test was higher than that in the static test.When the water TP was 20 mg/L,there was moderate pollution in the sediment of disturbance test,and the rest sediments were all in mild pollution.The TP sediments exceeded the tolerance bound of most benthic faund and had a low ecological risk to the benthic fauna.(3)Phosphorus adsorption by sediment was physical absorption,and the total content of the four forms of inorganic phosphorus in the sediment of disturbance test was higher than that in sediment of static test.Water disturbance would increase the phosphorus availability of sediment,and further increase the ecology risk of water.