贡湖生态修复区水质净化模拟与净化能力

利用三维水质模型，对藻类生长以及沉水植物（穗花狐尾藻、菹草、苦草）的生长和分布进行模拟，探讨春、夏不同季节情况下，贡湖生态修复区对流域内流入的氮、磷污染负荷的净化效果，旨在进一步定量地揭示沉水植物对富营养化水体净化的重要作用.结果表明贡湖生态修复区夏季（7~9月）出水口IV类水水质达标率略优于春季（3~5月），主要体现在春季氮、磷污染负荷流入，刺激藻类生长，叶绿素a浓度较高；夏季沉水植物生长旺盛，能够与藻类竞争营养盐，从而抑制藻类生长.考虑氮磷污染物流入湖体的后续效应，180d内春季贡湖生态修复区总氮、总磷平均稀释净化效率分别为74.76%和71.00%，180d内夏季贡湖生态修复区总氮、总磷平均稀释净化效率分别为73.20%和64.65%.修复区最大净化能力估算结果为加强生态修复区的管理，保障清水还湖水质提供了参考依据.

Numerical simulation of water purification and estimation of purifying capacity in Gonghu ecological restoration area

Using 3D water quality model, we simulated the growth of algae and the growth and the distribution of submerged macrophytes (Myriophyllum spicatum L., Potamogeton crispus, Vallisneria natans) and compared the effect of water purification of nutrients in Gonghu ecological restoration area in spring and summer, aiming at further quantitatively revealing the important role of submerged macrophytes in the purification of eutrophic water bodies. The results showed that:The class IV water attainment rate of the ecological area discharge in summer (July~September) is higher than that in spring (March-May). In spring, the algae grow fast with the nitrogen and phosphorus nutrients inflowing, which can result in a higher concentration of chlorophyll a. However, a large amount of submerged macrophytes can complete with algae for nutrients, thereby inhibiting algal growth. Considering the follow-up effect of nutrients inflowing, the average dilution and purification efficiency of total nitrogen and total phosphorus in Gonghu ecological restoration area were 74.76% and 71.00% respectively in 180days when the nutrients inflowed in spring, and 73.20% and 64.65% when the nutrients inflowed in summer. The estimation results of the maximum purifying capacity can provide a reference for strengthening the management of ecological restoration area and ensuring the water quality of the lake.