摘要
通过对夏秋季节滇池湖滨藻积层全面系统调研以及湖区底泥内源释放通量研究,旨在厘清滇池藻类沉积特性及其对内源污染负荷贡献.基于全湖24个断面,96个剖面特征系统调研,发现滇池底泥藻类生物量续存由北向南逐步减轻,外海东部湖区贮存量远高于西部,其演变趋势与多年来滇池蓝藻水华空间分布异质特性相一致.全湖湖滨水域整体分布格局为:外海中部(577.92ng/g)>外海北部(521.32ng/g)>草海(276.55ng/g)>外海南部(240.05ng/g).滇池藻积层厚度范围基本维持在5~10cm,其中深度0~10cm富集区域(即新鲜藻碎屑沉降富集区)占比约27%,而集中在深度10~15cm富集区占比25%以上.草海和外海北部表、中、下层叶绿素a含量没有明显差异,这与草海表层浮泥再悬浮过程以及外海北部常年风浪扰动下底泥再悬浮密切相关.经初步核算,草海底泥藻类生物量3.65g/m^(2),贡献了底泥藻源性氮磷分别为26.4t和2.5t.外海6.43g/m^(2),贡献了底泥藻源性氮磷分别为46.6和4.5t.底泥-上覆水界面处SRP平均释放速率为2.45mg/(m^(2)·d),NH_(4)^(+)-N平均释放速率为138.21mg/(m^(2)·d),均以释放为主.外海北部、中部湖滨水域的SRP和NH_(4)^(+)-N释放速率高于草海、外海南部,这与藻积层分布特性高度吻合,这可能是滇池藻源性氮磷在更深程度上影响底泥氮磷释放主要证据之一.另外进一步分析发现滇池底泥Chla含量与SRP、NH_(4)^(+)-N释放速率呈显著正相关.滇池底泥内源释放风险呈现北高南低的空间差异,外海北部(藻类沉积量高及强扰动作用)和外海中部(藻类沉积量高)属内源氮磷释放高风险区,水域水质整体相对较差,底泥埋藏藻源性氮磷释放影响是其主要原因之一.草海及外海南部当前风险较低,但仍需加强管控监测.藻积层治理作为内源污染控制的关键环节,底泥藻源性氮磷富集与释放风险管控是今后滇池内源治理重点方向之一.
Through comprehensive systematic surveys of algal accumulation layers along the shores of Dianchi Lake during summer and autumn,coupled with studies on the release flux of endogenous pollutants within the lake,this research aims to clarify the sedimentation characteristics of algae in Dianchi Lake and their contribution to endogenous pollution loads.Based on systematic surveys of 24 lake-wide cross-sections and 96 profile characteristics,it was found that the residual algal biomass in Dianchi Lake sediments gradually decreases from north to south.The storage volume in the eastern outer lake area is significantly higher than that in the western area,and this trend aligns with the spatial distribution heterogeneity of cyanobacterial blooms in Dianchi Lake over the years.The overall distribution pattern across the lake's littoral zone was:Central Outer Lake(577.92ng/g)>Northern Outer Lake(521.32ng/g)>Caohai(276.55ng/g)>Southern Outer Lake(240.05ng/g).The thickness of the algal layer in Dianchi Lake generally ranged between 5and 10cm.The 0~10cm depth zone(representing the fresh algal detritus settling and accumulation area)accounted for approximately 27%of the total thickness,while the 10~15cm depth zone contributed over 25%.No significant differences were observed in surface,middle,and bottom layer chlorophyll a concentrations between Caohai and the northern Outer Lake.This correlates closely with the resuspension of surface floc in Caohai and the year-round wind-wave disturbance causing sediment resuspension in the northern Outer Lake.Preliminary calculations indicate Caohai sediment algal biomass at 3.65g/m^(2),contributing 26.4t and 2.5t of algal-derived nitrogen and phosphorus,respectively.In the outer lake,the biomass was 6.43g/m^(2),contributing 46.6t and 4.5t of algal-derived nitrogen and phosphorus from the sediment,respectively.At the sediment-water interface,the average release rate of SRP was 2.45mg/(m^(2)·d),and the average release rate of NH_(4)^(+)-N was 138.21mg/(m^(2)·d),both dominated by release processes.SRP and NH_(4)^(+)-N release rates in the northern and central coastal waters of the outer lake were higher than those in Caohai and the southern outer lake,closely aligning with algal accumulation layer distribution characteristics.This may serve as primary evidence that algal-derived nitrogen and phosphorus in Dianchi Lake profoundly influence sediment nitrogen and phosphorus release.Furthermore,analysis revealed a significant positive correlation between Chla content in Dianchi sediment and SRP/NH_(4)^(+)-N release rates.The risk of endogenous release from Dianchi Lake sediments exhibits spatial variation,being higher in the north and lower in the south.The northern Outer Lake(high algal deposition and strong disturbance)and central Outer Lake(high algal deposition)are high-risk zones for endogenous nitrogen and phosphorus release,characterized by relatively poorer overall water quality.The release of algal-derived nitrogen and phosphorus from buried sediments is one of the primary contributing factors.The southern parts of Caohai and the outer lake currently exhibit lower risks but still require enhanced management and monitoring.As a critical component of endogenous pollution control,managing the enrichment and release risks of algal-derived nitrogen and phosphorus in sediments will be a key focus for future endogenous pollution control in Dianchi Lake.
作者
古倩倩
李杨
蔡健霞
谢冬
童丞飞
古小治
潘继征
陈开宁
范成新
GU Qian-qian;LI Yang;CAI Jian-xia;XIE Dong;TONG Cheng-fei;GU Xiao-zhi;PAN Ji-zheng;CHEN kai-ning;FAN Cheng-xin(School of Ecology and Environment,Nanjing Forestry University,Nanjing 210037,China;Kunming Dianchi and Plateau Lakes Institute,Kunming 650228,China;State Key Laboratory of Lake and Watershed Science for Water Security,Nanjing Institute of Geography and Lakes,Chinese Academy of Sciences,Nanjing 211135,China)
出处
《中国环境科学》
北大核心
2025年第12期6659-6670,共12页
China Environmental Science
基金
国家自然科学基金资助面上项目(42177227)
江苏省社会发展项目(BE2022858)
天津市科技项目(HLZC2024009)
云南省重点研发项目(202503AT100002-03)
苏州市级重要湿地健康评价与生态质量等级核算(JSZC-320500-SZWK-C2025-0279)。
关键词
滇池
藻类沉积
底泥
内源
释放速率
Dianchi
algal deposition
sediment
endogenous
release rate
