Abstract
The algal blooms caused by the eutrophication of lakes is a major environmental problem. In this study, we took China’s Taihu Lake as the research area, using multi-source satellite imagery data to monitor the information of algal blooms from 2008 to 2017. Following the analyses of the temporal and spatial variation trends of the blooms, water quality and meteorological data from land observation stations were employed to investigate the main environmental driving forces of the algal bloom outbreaks. The results show that, over the decade, the blooms with medium and higher hazard degrees mainly occurred in summer and autumn, and especially in autumn. From 2008 to 2016, the algal blooms outbreak degree was relatively stable, but, in 2017, it was severe, and the Northwest Lake area and the northern bays had heavier blooms than the other lake areas. From the analyses of the environmental driving forces, the variation trend of total nitrogen (TN) and total phosphorus (TP) concentrations in Taihu Lake from 2008 to 2017 was moderate, and the minimum concentrations of TN and TP both exceeded the threshold for algal bloom outbreaks. It was also found that the algal bloom area had notable correlations with the sunshine duration, wind speed and direction, precipitation, and air pressure. The research results of this paper will provide a theoretical basis for the scientific prediction of the occurrence of algal blooms in Taihu Lake.
Highlights
Algal blooms are one of the most serious ecological and environmental problems affecting water bodies, and they can have a major impact on both human and ecosystem health
The lowest values of total phosphorus (TP) and total nitrogen (TN) concentrations are significantly higher than the above criteria, and they fully satisfy the nutrient concentration conditions required for the outbreak of the cyanobacteria bloom; the type of blooms that occurred during the study period was cyanobacteria blooms
Satellite remote sensing technology provides us with the possibility to quickly and extensively monitor algal blooms in water
Summary
Algal blooms are one of the most serious ecological and environmental problems affecting water bodies, and they can have a major impact on both human and ecosystem health. Hu et al [13] used Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing image data from 2000 to 2008 to identify the algal bloom information of Taihu Lake by employing the floating algae index (FAI), and analyzed its temporal and spatial distribution characteristics. In this study, based on the above analysis, we utilized multi-source optical and radar remote sensing datasets, including Landsat 5–8, Gaofen-1 (GF-1), Sentinel-2, and Sentinel-1 satellite data, to identify and extract the algal bloom information for Taihu Lake from 2008 to 2017. On this basis, Water2020, 2020,12, 12,1035 x FOR PEER REVIEW.
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