Human and natural impacts on the U.S. freshwater salinization and alkalinization: A machine learning approach
Human and natural impacts on the U.S. freshwater salinization and alkalinization: A machine learning approach
复制标题
人类和自然对美国淡水盐化和碱化的影响：机器学习方法
DOI：
10.1016/j.scitotenv.2023.164138
复制
发表时间：
2023
影响因子：
9.8
通讯作者：
Wen, Tao
中科院分区：
文献类型：
--
作者：
E, Beibei;Zhang, Shuang;Driscoll, Charles T.;Wen, Tao
在之前的研究中，美国河流中持续的盐碱化和碱化被归因于道路盐的输入和人类加速风化的影响。盐碱化对人类和生态系统的健康构成严重威胁，而人类活动引起的碱化意味着陆地对大气二氧化碳封存动态的不确定性增加。关于人类活动是否以及如何加速风化和促进美国河流的地球化学变化的机制理解是缺乏的。为了解决这一不确定性，我们收集了美国226个河流监测点的溶解钠（盐度代理）和碱度值，以及包括水文、气候、地貌、地质、土壤化学、土地利用和土地覆盖在内的32个流域属性。利用这些数据，我们建立了两个机器学习模型来预测这些地点的月聚合钠和碱度通量。钠预测模型检测到人类活动（以人口密度和不透水表面积为代表）是美国河流含盐量的主要贡献者。相比之下，碱度预测模型认为自然过程是河流碱度通量变化的主要原因，包括径流、碳酸盐沉积物或硅质泥沙、土壤pH和土壤水分。与之前的研究不同，我们的分析表明，美国河流的碱化在很大程度上是由当地的气候和水文地质条件决定的。
Ongoing salinization and alkalinization in U.S. rivers have been attributed to inputs of road salt and effects of human-accelerated weathering in previous studies. Salinization poses a severe threat to human and ecosystem health, while human derived alkalinization implies increasing uncertainty in the dynamics of terrestrial sequestration of atmospheric carbon dioxide. A mechanistic understanding of whether and how human activities accelerate weathering and contribute to the geochemical changes in U.S. rivers is lacking. To address this uncertainty, we compiled dissolved sodium (salinity proxy) and alkalinity values along with 32 watershed properties ranging from hydrology, climate, geomorphology, geology, soil chemistry, land use, and land cover for 226 river monitoring sites across the coterminous U.S. Using these data, we built two machine-learning models to predict monthly-aggregated sodium and alkalinity fluxes at these sites. The sodium-prediction model detected human activities (represented by population density and impervious surface area) as major contributors to the salinity of U.S. rivers. In contrast, the alkalinity-prediction model identified natural processes as predominantly contributing to variation in riverine alkalinity flux, including runoff, carbonate sediment or siliciclastic sediment, soil pH and soil moisture. Unlike prior studies, our analysis suggests that the alkalinization in U.S. rivers is largely governed by local climatic and hydrogeological conditions.