枯水季"引江济太"工程对受水河湖水体磷素分布的影响OA

The Water Diversion from Yangtze River to Lake Taihu(WDYT)is a major engineered water transfer project designed to improve the water quality of Lake Taihu.However,its impact on lake phosphorus dynamics,especially the contribution of bioavail-able phosphorus and its linkage to algal bloom risk,remains inadequately understood.This study aimed to evaluate the degree and contribution of the WDYT to phosphorus variations in Lake Taihu and to examine its association with algal bloom potential.Focu-sing on the Wangyu River diversion channel and the receiving Gonghu Bay,with the central lake zone as a reference area,field sampling was conducted during dry seasons(autumn and winter)from 2018 to 2022.Parameters monitored included total phos-phorus(TP),total dissolved phosphorus(DTP),soluble reactive phosphorus(SRP),chlorophyll-a(Chl.a),and other physico-chemical factors;particulate phosphorus(PP)and dissolved organic phosphorus(DOP)were derived.Statistical analyses were employed to assess the influence of water diversion on aquatic phosphorus forms and its correlation with algal indicators.Results in-dicated that phosphorus concentrations in the Wangyu River decreased along the flow path from the Yangtze River to the lake inlet during autumn diversion periods,whereas they fluctuated and increased overall in winter.From Gonghu Bay toward the central lake,concentrations of TP,DTP,SRP,and DOP showed fluctuating yet generally increasing trends during both diversion and non-diversion periods in autumn and winter.The average proportion of PP in Gonghu Bay during diversion periods was 43.16％in autumn and 37.33％in winter,higher than during non-diversion periods(37.33％and 20.16％,respectively).Nevertheless,phosphorus concentrations in the Wangyu River inflow were generally similar to or lower than those in the central lake zone.Dry-season diversion did not significantly increase phosphorus levels in Gonghu Bay,particularly dissolved bioavailable phosphorus.Chl.a in Gonghu Bay correlated with water temperature and turbidity in autumn,whereas it was significantly associated with DO and pH in winter.No significant correlation was found between Chl.a and phosphorus concentrations.Under the operation of the Wangyu River western control project,dry-season diversion does not substantially raise the phosphorus load in the receiving lake ar-ea,especially regarding dissolved bioavailable phosphorus directly available to phytoplankton.Thus,phytoplankton growth in Gon-ghu Bay during the dry season is not sensitive to phosphorus concentrations.Although the phosphorus introduced via diversion shows limited short-term ecological effects,its long-term accumulation and potential role in promoting algal blooms in Lake Taihu require further investigation.