水生植物刈割对生态沟渠中氮、磷拦截的影响

Effects of cutting aquatic plants on nitrogen and phosphorus interception in ecological ditches

本研究选用生态沟渠中水生美人蕉、铜钱草、黑三棱、穗花狐尾藻和灯心草作为试验植物,通过比较刈割区和未刈割区底泥样和植物样氮、磷含量及水样氮、磷去除率,分析刈割措施对生态沟渠拦截氮、磷效果的影响。结果表明,5种植物(300 m2)2次刈割试验共带走全氮11.889 kg和全磷1.099 kg;其中,不同植物收获全氮表现为水生美人蕉(7.686 kg)>穗花狐尾藻(1.501 kg)>铜钱草(1.128 kg)>灯心草(0.974 kg)>黑三棱(0.601 kg),收获全磷表现为水生美人蕉(0.433 kg)>穗花狐尾藻(0.233 kg)>黑三棱(0.191 kg)>铜钱草(0.134 kg)>灯心草(0.109 kg)。刈割管理还可以提高沟渠底泥中氮、磷的去除率(黑三棱除外)。与未刈割区相比,刈割提高底泥全氮和全磷的去除率次序分别为穗花狐尾藻(20.73%)>铜钱草(20.00%)>灯心草(16.05%)>水生美人蕉(4.86%)>黑三棱(9.72%)和灯心草(20.69%)>铜钱草(16.67%)>水生美人蕉(4.55%)>穗花狐尾藻(0.00%)>黑三棱(16.00%)。刈割后的水体氮、磷去除结果也说明植物刈割可以提高水生植物对氮、磷的净化效果。因此,植物刈割管理既能直接转移出沟渠中的营养物质,也提高了沟渠底泥和水体中氮、磷的去除效率。

In this study, Canna glauca, Hydrocotyle vulgaris, Sparganium stoloniferum, Myriophyllum spicatum and Juncus effusus aquatic plants were planted in an ecological ditch. The effects of plant cutting management on nitrogen （N） and phosphorus （P） interception in ecological ditches were then analyzed by N and P content comparisons and removal rates in water samples. The resuits showed that the amounts of total N and P removed by cutting aquatic plants in September and November were 11.889 kg and 1.099 kg, respectively, in the 300 m2 ecological ditch. Total N uptake by different aquatic plants was in the order of C. glauca （7.686 kg） 〉 34.. spicatum （1.501 kg） 〉 H. vulgaris （1.128 kg） 〉 J. effusus （0.974 kg） 〉 S. stoloniferum （0.601 kg）. The order for total P was C. glauca （0.433 kg） 〉 M. spicatum （0.233 kg） 〉 S. stoloniferum （0.191 kg） 〉 1t. vulgaris （0.134 kg） 〉 J. effusus （0.109 kg）. Cutting plants also improved N and P removal efficiency in ditch sediments, except for S. stoloniferum. Compared to non-cutting areas, cutting areas showed increased sediment total N nutrient removal rates with M.. spicatum （20.73%） 〉 tt. vulgaris （20.00%） 〉 J. ejZ fusus （16.05%） 〉 C. glauca （4.86%） 〉 S. stoloniferum （-9.72%）. That for total P was J. effusus （20.69%） 〉 H. vulgaris （16.67%） 〉 C. glauca （4.55%） 〉 M. spicatum （0.00%） 〉 S. stoloniferum （-16.00%）. N and P removal rates in water also increased under cutting treatment. Thus cutting aquatic plants not only removed nutrients from ditch systems, but also increased N and P interception in water and ditch sediments.