太湖主体湖区对梅梁湾藻类影响定量化研究

QUANTITATIVE STUDY ON THE INFLUENCE OF LAKE TAIHU'S MAIN ZONE UPON MEILIANG BAY

针对太湖梅梁湾独特的地理位置和富营养化严重的问题,利用太湖水量水质模型和梅梁湾藻类生长模型,在对模型进行了率定、验证的基础下,模拟了在东南风和西北风两种常见风向的条件下,太湖主体湖区对梅梁湾内营养盐浓度和藻类浓度的影响情况,并将其影响定量化。本次模拟较好地反映了太湖主体湖区在两种常见风场的条件下对梅梁湾内水质影响情况。模拟得到以下结果:在不考虑风场和流场的情况下,梅梁湾内部2001年8月藻类平均浓度为43.18mg/m3,总氮浓度为2.48mg/L,总磷浓度为0.248mg/L,只考虑东南风引起流场的情况下,藻类浓度为41.92mg/m3,总氮浓度为2.07mg/L,总磷浓度为0.231mg/L;考虑东南风风场和流场两个因素的情况下,藻类浓度为53.86mg/m3,总氮浓度为2.06mg/L,总磷浓度为0.229mg/L;同期,只考虑西北风风场的情况下,藻类浓度为42.55mg/m3,总氮浓度为2.19mg/L,总磷浓度为0.232mg/L;考虑西北风风场和流场两个因素的情况下,藻类浓度为50.71mg/m3,总氮浓度为2.17mg/L,总磷浓度为0.233mg/L。结果表明,梅梁湾内部的氮、磷等营养盐浓度受到由太湖主体湖区的风场变化引起的湖流扰动的一定影响;太湖主体湖区对梅梁湾内部藻类浓度的影响主要是由藻类漂移引起的,由营养盐浓度改变而引起的藻类浓度变化非常小。

The Meiliang bay is suffered from eutrophication problem.Considering the unique geographical position of Meiliang Bay at Lake Taihu,both fixed and validated two-dimension water quality model and alga growing model were used to simulate the effect on nutrition and algae concentration in Meiliang Bay by main zone of Lake Taihu under south-east and north-west wind.The simulated results showed as follow：in August,2001,the average concentration of algae of Meiliang bay was 43.18 mg/m^3.At the same time,the average concentration of nitrogen and phosphorus were 2.48 and 0.248 mg/L.If the parameter of flow index induced by south-east wind was added to these models,the concentration of algae,nitrogen and phosphorous were obtained to be 41.92 mg/m^3,2.07 mg/L and 0.231 mg/L and 42.55 mg/m^3,2.19 mg/L,0.232 mg/L respectively under the influence of north-west wind effect.Considering both the influence of flow and excursion caused by south-east wind,the concentration of algae,nitrogen and phosphorous changed to be 53.86 mg/m^3,2.06 mg/L and 0.229 mg/L and 50.71 mg/m^3,2.17 mg/L,0.233 mg/L when wind direction transferred to north-west.The results indicated that the concentration of nitrogen and phosphorus in Meiliang Bay were affected by the flow of Lake Taihu to a certain extent and the change of alga in Meiliang Bay was mainly caused by the excursion of algae.The results agreed with the observation data very well and were considered to provide some supports for dealing with eutrophication of Lake Taihu.