Gupta Surya, Scheper Simon, Borrelli Pasquale, Panagos Panos, Alewell Christine
Department of Environmental Sciences, University of Basel, Basel, Switzerland.
Dr. Simon Scheper-Research | Consulting | Teaching, Dähre, Germany.
Glob Chang Biol. 2025 Sep;31(9):e70494. doi: 10.1111/gcb.70494.
Soil erosion by water is a critical factor contributing to eutrophication in water bodies, acting as a significant source of nitrogen and phosphorus from land. Many models predict soil erosion and sediment transport into lakes and rivers, and the connection between soil erosion triggering eutrophication is considered textbook knowledge. However, limited data-based scientific evidence exists on the consequences of soil erosion and sediment fluxes on eutrophication. This study examines the impact of soil erosion on eutrophication, considering other covariates such as slope, elevation, phosphorus, nitrogen, flow accumulation and temperature, by analyzing zones of varying sizes around lakes in six different countries of Europe covering an area of 1596 km: Austria (81 lakes), France (310), Germany (266), Hungary (73), Poland (465), and the United Kingdom (316). We utilized multispectral Sentinel-2 satellite remote sensing data at 20-m spatial resolution for 2021 and 2022 to estimate the Floating Algae Index (FAI) of lakes. FAI allowed us to quantify bloom occurrence (BO)-the frequency of detected algal blooms-and maximum bloom extent (MBE)-the total area affected by blooms during the study period. The MBEs were then correlated with the aforementioned covariates within zones of 100 m, 200 m, 500 m, and 1 km distance from the lakes using machine learning algorithms to identify the most significant and thus driving factors within these areas. Our results prove quantitatively that soil erosion is indeed a key driver of eutrophication for all the selected European regions except Austria. Water temperature, nutrient input, and slope are additional important drivers of lake eutrophication.
水蚀土壤是导致水体富营养化的关键因素，是陆地氮和磷的重要来源。许多模型预测土壤侵蚀和泥沙向湖泊和河流的输送，土壤侵蚀引发富营养化之间的联系被视为教科书知识。然而，关于土壤侵蚀和泥沙通量对富营养化影响的基于数据的科学证据有限。本研究通过分析欧洲六个不同国家湖泊周围不同大小区域（面积1596平方千米）的情况，考虑其他协变量，如坡度、海拔、磷、氮、水流累积和温度，来研究土壤侵蚀对富营养化的影响。这六个国家分别是奥地利（81个湖泊）、法国（310个）、德国（266个）、匈牙利（73个）、波兰（465个）和英国（316个）。我们利用2021年和2022年空间分辨率为20米的多光谱哨兵-2卫星遥感数据来估算湖泊的浮游藻类指数（FAI）。FAI使我们能够量化水华发生频率（BO）——检测到的藻类水华的频率——以及最大水华范围（MBE）——研究期间受水华影响的总面积。然后，使用机器学习算法将MBE与距湖泊100米、200米、500米和1千米范围内的上述协变量进行关联，以确定这些区域内最重要的驱动因素。我们的结果定量证明，除奥地利外，土壤侵蚀确实是所有选定欧洲地区富营养化的关键驱动因素。水温、养分输入和坡度是湖泊富营养化的其他重要驱动因素。
