Thirty-Four-Year Record (1987-2021) of the Spatiotemporal Dynamics of Algal Blooms in Lake Dianchi from Multi-Source Remote Sensing Insights
Thirty-Four-Year Record (1987-2021) of the Spatiotemporal Dynamics of Algal Blooms in Lake Dianchi from Multi-Source Remote Sensing Insights
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DOI：
10.3390/rs14164000
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发表时间：
2022-08-01
期刊：
影响因子：
5
通讯作者：
Luo, Juhua
中科院分区：
文献类型：
--
作者：
Ma, Jinge;He, Feng;Luo, Juhua
滇池是我国富营养化程度最高的湖泊之一。水质的下降和大量藻类水华的发生对水生态系统的健康和环境安全构成了重大威胁，使滇池成为中国藻类水华管理的关键问题。获得尽可能长时间的水华时空动态是至关重要的水华管理和未来的预测。然而，由于传感器的空间和时间分辨率的限制，很难从单个传感器获得藻类水华的长期记录，以覆盖更长的富营养化时期。利用陆地卫星和中分辨率成像光谱仪（MODIS）遥感影像，结合浮游藻类指数（FAI）重建统一的水华面积时间序列，分析滇池近几十年来的水华动态。在年际变化方面，1987 - 2021年水华面积呈增加趋势，1991-1992年、2000-2003年、2012-2013年和2020-2021年水华面积较大。从季节特征来看，一年中，水华面积在雨季比旱季明显更为突出。水华发生频率的空间分布呈现北高南低的格局。从2000年到2021年，初花期和花期持续时间分别呈现出推迟后提前和减少后增加的趋势。我们分析了藻类水华的长期记录的重要性，发现雨季图像的百分比是基于不同传感器重建时间序列的一个重要因素。此外，还分析了环境因子与水华的关系。结果表明，风速和气温是控制滇池水华年际变化的主要气象因子。营养盐等水质因素对水华变化的影响较小，因为藻类生长的需求已经得到满足。地方政府采取的环境管理措施使滇池的营养状况得到改善，继续加强环境污染控制有望遏制滇池水华。该研究提供了滇池水华的长期记录，为全面了解滇池水华的发展过程及其可持续发展提供了必要的参考信息。
Lake Dianchi is one of the most eutrophic lakes in China. The decline in water quality and the occurrence of massive algal blooms pose a significant threat to the health and environmental safety of the water ecosystem, making Lake Dianchi a key concern for algal bloom management in China. Obtaining the spatiotemporal dynamics of algal blooms for the longest time possible is crucial to algal bloom management and future prediction. However, it is difficult to acquire a long-term record of algal blooms from a single sensor in order to cover a more extended period of eutrophication in the lake due to the limitation of the spatial and temporal resolution of the sensors. In this study, Landsat and Moderate-Resolution Imaging Spectroradiometer (MODIS) images were combined with the Floating Algae Index (FAI) to reconstruct a unified time series of bloom areas to analyze the algal bloom dynamics in Lake Dianchi in recent decades. Regarding the interannual variation, the bloom area showed an increasing trend from 1987 to 2021, with larger bloom areas in 1991-1992, 2000-2003, 2012-2013, and 2020-2021. In terms of seasonal characteristics, the bloom area was significantly more prominent in the rainy season compared with the dry season during the year. The spatial distribution of the bloom frequency showed a pattern of higher frequencies in the north and lower frequencies in the south. From 2000 to 2021, the initial bloom time and bloom duration showed a trend of delaying and then advancing and decreasing and then increasing, respectively. We analyzed the importance of long-term records of algal blooms and found that the percentage of rainy season images is an essential factor in reconstructing time series based on different sensors. In addition, the relationship between environmental factors and algal blooms was analyzed. The results show that wind speed and air temperature were the main meteorological factors controlling the interannual variation in algal blooms in Lake Dianchi. Water quality factors such as nutrients have less of an influence on the variation in algal blooms because the algal growth demand has been met. Environmental management measures taken by local governments have led to improvements in the lake's trophic state, and continued strengthening of environmental pollution control is expected to curb the algal blooms in Lake Dianchi. This study provides a long-term record of algal blooms in Lake Dianchi, which provides essential reference information for a comprehensive understanding of the development process of algal blooms in Lake Dianchi and its sustainable development.