Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Yunnan Institute of Environmental Science (Kunming China International Research Center for Plateau Lake), Kunming 650034, China.
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
J Environ Sci (China). 2018 Oct;72:185-197. doi: 10.1016/j.jes.2018.01.005. Epub 2018 Jan 17.
To assess the seasonal and spatial variations and long-term trends in water optical properties in Lake Fuxian, investigations based on field work in four seasons and a long-term analysis of data from 1980 to 2014 were conducted. The results show that there was no significant variation in the euphotic depth (Z) across the four seasons, and no significant correlations between Z and potential influencing factors in seasons other than summer, suggesting that the water itself may be a major factor regulating the Z in general. Nevertheless, significant differences in Z between the north region (NR) and the south region (SR) were observed in all seasonal tests except spring. This finding relates to a higher abundance of chromophoric dissolved organic matter (CDOM) in the NR due to runoff, especially in the rainy seasons (summer and autumn). CDOM and its terrigenous component had an important impact on Z in summer, with the highest precipitation, and impacts from suspended solids and non-algal particles were also found in the NR in summer. The Secchi disk depth in the lake decreased clearly over the years, with significantly negative correlations with the increasing permanganate index and air temperature, implying that organic contaminants (CDOM and/or phytoplankton) are important regulators of water transparency. We estimate that the combined effects of climate warming and changes in land use and land cover are also indirect regulating factors. These findings should be considered in the protection of Lake Fuxian, owing to the importance of light penetration in aquatic ecosystems.
为了评估抚仙湖水体光学性质的季节性和空间变化及长期趋势，我们进行了基于四季实地调查和 1980 年至 2014 年长期数据分析的研究。结果表明，在四个季节中，透光深度（Z）没有明显变化，在夏季以外的季节中，Z 与潜在影响因素之间没有显著相关性，这表明水本身可能是普遍调节 Z 的主要因素。然而，除春季外，在所有季节的测试中，北部地区（NR）和南部地区（SR）的 Z 存在显著差异。这一发现与由于径流入湖导致的 NR 中更高丰度的有色溶解有机物（CDOM）有关，尤其是在雨季（夏季和秋季）。CDOM 及其陆源成分对夏季（降水最多）的 Z 有重要影响，夏季 NR 中的悬浮物和非藻类颗粒也有影响。湖泊的塞奇圆盘深度多年来明显下降，与高锰酸盐指数和空气温度的增加呈显著负相关，这意味着有机污染物（CDOM 和/或浮游植物）是水透明度的重要调节因素。我们估计，气候变暖以及土地利用和土地覆盖变化的综合影响也是间接调节因素。鉴于光穿透对水生生态系统的重要性，这些发现应该在抚仙湖的保护中得到考虑。
