夏季太湖浊度分布特征及其在水－沉积物界面识别中的应用

基于2014年8月对太湖61个采样点的浊度和各物理化学指标的测定,分析夏季太湖浊度空间、垂直分布特征及其影响因素,利用实测的湖泊底层浊度垂直分层对水－沉积物界面进行定量识别.结果表明,夏季太湖浊度表、中、底层浊度平均值分别为(28.3±21.4), (23.0±13.3), (31.7±15.0) NTU,总体分布趋势为太湖北部贡湖湾、梅梁湾最大,其次为西部及湖心区,较低值出现在胥口湾及东太湖;线性回归分析表明,表、中、底层浊度分别与叶绿素a、无机悬浮物、总悬浮物浓度的拟合关系最好;基于浊度垂直分层定量识别的太湖水－沉积物界面厚度均值为(156.4±53.5) mm,其中贡湖湾及太湖西部厚度最大,其次为湖心区及梅梁湾,东太湖、胥口湾、竺山湾界面厚度最小,界面厚度与中层浊度存在显著的正相关(R2=0.552),风浪引起的频繁的沉积物再悬浮将增加水－沉积物界面厚度.太湖浊度的垂直分层可用于水－沉积物界面的定量识别,为水－沉积物界面营养盐交换和物质循环研究提供科学依据.

Characteristics of turbidity in summer in Lake Taihu and its application to the identification of water-sediment interface

A field investigation was conducted of 61stations in Lake Taihu (summer, 2014). Based on the field measurements of several physical and chemical parameters, we first characterized the turbidity spatial and vertical distribution and analyzed its affecting factors. Then, water-sediment interface was identified using the measured vertical stratification of turbidity at the bottom in Lake Taihu. The results showed that the mean values of turbidity of surface, middle, and bottom layers were (28.3 ± 21.4), (23.0 ± 13.3), (31.7 ± 15.0) NTU, respectively. The maximum turbidity appeared in the northern regions of Lake Taihu, including Meiliang Bay and Gonghu Bay, followed by the southwestern open water. However, East Lake Taihu and Xukou Bay showed the lowest turbidity. The best predictor of turbidity of the surface, middle and bottom layers was the concentrations of chlorophyll a, inorganic suspended matter, and total suspended matter, respectively. The thickness of the water-sediment interface ranged from 45.0to 229.0mm with a mean value of (156.4 ± 53.5) mm. The higher thickness was observed in Gonghu Bay and southwestern open water. In contrast, the lower thickness appeared in East Lake Taihu and Xukou Bay. Significantly positive correlation was found between turbidity and the thickness of the water-sediment interface (R2=0.552). The study suggests that increasing turbidity frequently resulted from strong wind waves would increase the thickness of water-sediment interface. Therefore, the vertical stratification of turbidity can be used to quantitatively identify water-sediment interface thickness, which will provide scientific support for the study of nutrients exchange and material circulation between water-sediment interfaces.