School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Department of Geoscience and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
Sci Total Environ. 2021 Aug 10;781:146688. doi: 10.1016/j.scitotenv.2021.146688. Epub 2021 Mar 24.
The lakes on the Yangtze Plain, a critical source of freshwater and fisheries for hundreds of millions of people in China, have lost a considerable portion of their surface area due to reclamation since the 1950s. Landsat satellites can provide long-term collections of high-resolution images and thus offer great potential for hindcasting the lake reclamations of aquaculture zones and their long-term impacts on the lacustrine water color. Using Landsat observations from 1984 to 2018 and a Forel-Ule index (FUI) model, we studied the water color dynamics of 61 lakes on the Yangtze Plain. Three distinct change patterns were found among the 61 examined lakes, and 25 of the 61 lakes showed statistically significant changes in the annual hue angle values (P < 0.05). We further collected environmental parameter datasets (runoff, normalized difference vegetation index (NDVI), and wind speed) and a lacustrine reclamation dataset, and measured the concentrations of chlorophyll-a (Chl-a) and dissolved organic carbon (DOC) from two field trips. We investigated their correlations with water color change from different facets. The results showed that the long-term water color in 33 of the 61 lakes exhibited significant correlations with environmental factors. The reclaimed aquaculture zones in this region have caused differences in the water color between the reclaimed area and that in adjacent natural waters. The Chl-a and DOC levels derived from field surveys further confirmed that reclaimed aquaculture zones increased light-absorbing materials in the water and may deteriorate water quality. This study is an important step forward in understanding the water quality changes in lake ecosystems affected by human impacts and natural variability.
自 20 世纪 50 年代以来，由于围垦，长江中下游平原上为数亿中国人提供了重要淡水资源和渔业资源的湖泊，其湖面面积已大幅减少。Landsat 卫星可以提供长期的高分辨率图像采集，因此非常适合对水产养殖区的湖泊围垦及其对湖泊水色的长期影响进行回溯研究。本研究利用 1984 年至 2018 年的 Landsat 观测数据和 Forel-Ule 指数（FUI）模型，研究了长江中下游平原 61 个湖泊的水色动态。在 61 个受检湖泊中，发现了三种截然不同的变化模式，其中 25 个湖泊的年度色调角值发生了统计学上的显著变化（P < 0.05）。本研究进一步收集了环境参数数据集（径流量、归一化植被指数（NDVI）和风速）和湖泊围垦数据集，并在两次实地考察中测量了叶绿素-a（Chl-a）和溶解有机碳（DOC）的浓度。从不同方面研究了它们与水色变化的相关性。结果表明，在 61 个湖泊中有 33 个湖泊的长期水色与环境因素显著相关。该地区的围垦水产养殖区导致了围垦区和相邻自然水域之间的水色差异。实地调查得出的 Chl-a 和 DOC 水平进一步证实，围垦水产养殖区增加了水中的吸光物质，可能会恶化水质。本研究是理解受人类活动和自然变异性影响的湖泊生态系统水质变化的重要一步。
