School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China.
School of Environment, Nanjing University, Nanjing 210023, China.
Sci Total Environ. 2022 Apr 10;816:151617. doi: 10.1016/j.scitotenv.2021.151617. Epub 2021 Nov 17.
Understanding the sensitivity of the response of chlorophyll (Chla) to nutrients (e.g., nitrogen and phosphorus) concentrations is important for predicting cyanobacterial bloom risk. However, the processes by which nutrients in lake that affect cyanobacterial growth and outbreaks are nonlinear, gradual and spatially and temporally heterogeneous, and the single response thresholds of concentrations between nutrients and the Chla proposed in current studies maybe hardly reflect these characteristics. Due to three decades of rapid regional socio-economic development, the eutrophication in Taihu Lake of China is serious and there are cyanobacterial blooms every year. In this study, we quantified the interaction effects of different forms of nitrogen and phosphorus on Chla concentrations in lake water and sediment pore water. And a refined response threshold range with continuous variation was proposed to characterize the relationship between the Chla concentration and the NH-N, total nitrogen (TN) and total phosphorus (TP) concentrations. The results showed that TP was the dominant factor influencing the spatial variation of cyanobacteria blooms in most areas of Taihu Lake, followed by TN. TP should therefore be the highest priority for future pollution load reduction in Taihu Lake. The effects of the interactions between the pollution factors were greater than the sum of them individually. NH-N and dissolved inorganic phosphorus (DIP) are likely to be preferentially consumed by algae for growth and should be the focus of nutrient control efforts in Taihu Lake. For cyanobacterial risk prediction, prevention and control, NH-N, TN and TP concentrations of 0.06 mg/L, 2.89 mg/L and 0.06 mg/L, respectively, can be used to indicate the beginning of cyanobacterial blooms in Taihu Lake, and concentrations of 0.34 mg/L, 4.67 mg/L and 0.11 mg/L, respectively, can be used as reference thresholds to indicate serious cyanobacterial blooms.
了解叶绿素 (Chla) 对营养物质（如氮和磷）浓度的响应敏感性对于预测蓝藻水华风险非常重要。然而，影响蓝藻生长和爆发的湖泊营养物质的过程是非线性的、渐进的，并且在空间和时间上存在异质性，当前研究中提出的营养物质与 Chla 浓度之间的单一响应阈值可能很难反映这些特征。由于中国太湖地区三十年来快速的社会经济发展，太湖富营养化严重，每年都会发生蓝藻水华。在这项研究中，我们量化了不同形式的氮和磷对湖水和沉积物孔隙水中 Chla 浓度的相互作用效应。并提出了一个具有连续变化的细化响应阈值范围，以表征 Chla 浓度与 NH-N、总氮 (TN) 和总磷 (TP) 浓度之间的关系。结果表明，TP 是影响太湖大部分地区蓝藻水华空间变异的主导因素，其次是 TN。因此，未来太湖的污染负荷削减应优先考虑 TP。污染因子之间相互作用的影响大于它们各自的影响之和。NH-N 和溶解无机磷 (DIP) 很可能优先被藻类用于生长，应成为太湖营养物控制工作的重点。对于蓝藻水华风险预测、预防和控制，0.06 mg/L、2.89 mg/L 和 0.06 mg/L 的 NH-N、TN 和 TP 浓度可分别指示太湖蓝藻水华的开始，0.34 mg/L、4.67 mg/L 和 0.11 mg/L 的浓度可分别作为指示严重蓝藻水华的参考阈值。
