亚热带丘陵区湿地水生植物组合模式拦截氮磷的研究

摘要

人工湿地是农业面源污染治理的有效措施,植物构成及其组合模式是影响湿地污染消纳能力的关键.以湖南亚热带红壤丘陵区为研究区,通过人工湿地小区试验,选取对氮磷有较强吸收能力的浮水植物绿狐尾藻(Myriophyllum elatinoides)为主要植物,分别与黑三棱(Sparganium stoloniferum)、梭鱼草(Pontederia cordata)、铜钱草(Hydrocotyle vulgaris)、灯芯草(Juncus effusus)、野芋头(Calla palustris)、水花生(Alternanthera philoxeroides)等构成不同的植物组合模式,研究其对农村污水(COD:56.34~109.41 mg·L-1、TN:21.11~33.24 mg·L-1、TP:3.36~5.74 mg·L-1)的净化效果,旨为亚热带丘陵区农村污水人工湿地生态治理工程提供参数依据.结果表明,观测期内(7—11月),野芋头组合对COD去除效果最好,出水COD平均质量浓度为21.24 mg·L-1,平均去除率为72.9%.铜钱草组合对TN的去除效果最好,出水TN平均质量浓度为3.52 mg·L-1,平均去除率达到84.9%.梭鱼草组合对TP的去除效果最好,出水TP平均质量浓度为0.22 mg·L-1,平均去除率达到95.2%.各植物组合氮磷积累量分别在12.43~30.87 g·m-2和0.99~4.69 g·m-2之间,梭鱼草组合氮磷积累量最大(8月:N 30.87 g·m-2和11月:P 4.69 g·m-2).植物吸收占总氮磷去除的比例分别为17.3%~27.8%和10.3%~16.7%,其中,以梭鱼草组合对氮磷的吸收比例最大,野芋头组合吸收比例最小.综合而言,绿狐尾藻与梭鱼草组合为研究区最佳湿地水生植物组合模式.%Constructed wetlands (CWs) are effective action of agricultural non-point source pollution control. Plant composition and combination pattern are the key of effect of CWs on the pollution control ability. As a case study, we selected subtropical hilly red soil region of Hunan. Based on the CWs experiments, we studied dominant plant Myriophyllum elatinoides, which had high removal rate of nitrogen (N) and phosphorus (P), combined with Sparganium stoloniferum, Pontederia cordata, Hydrocotyle vulgaris, Juncus effuses, Calla palustris, Alternanthera philoxeroides, respectively. Our study were to investigate removal efficiency of these combination patterns for treating rural sewage (COD: 56.34~109.41 mg·L-1, TN: 21.11~33.24 mg·L-1, TP: 3.36~5.74 mg·L-1). From July to November, our results showed that the removal rates of COD was the best and high up to 72.9% by M. elatinoides and C. palustris composite pattern, and effluent's average concentration of COD was 21.24 mg·L-1. The removal rates of TN was the best and high up to 84.9% by M. elatinoides and H. chinensis composite pattern, and effluent's average concentration of TN was 3.52 mg·L-1. The removal rates of TP was the best and high up to 95.2% by M. elatinoides and P. cordata composite pattern, and effluent's average concentration of TP was 0.22 mg·L-1. N and P accumulation quantity ranged from 12.43 g·m-2 to 30.87 g·m-2, from 0.99 g·m-2 to 4.69 g·m-2, respectively, in different composite patterns. N and P accumulation quantity were the most by M. elatinoides and P. cordata combination pattern (Augest: N 30.87 g·m-2, November: P 4.69g·m-2). The N and P absorption removal rate of plant uptake were 17.3%~27.8% and 10.3%~16.7%, respectively. N and P uptake percentage were most by M. elatinoides and P. cordata composite pattern, N and P uptake percentage were least by M. elatinoides and C. palustris composite pattern. In general terms, M. elatinoides and P. cordata composite pattern was the best optimal in the studied area.