Effects of land use on lake nutrients: the importance of scale, hydrologic connectivity, and region

Catchment land uses, particularly agriculture and urban uses, have long been recognized as major drivers of nutrient concentrations in surface waters. However, few simple models have been developed that relate the amount of catchment land use to downstream freshwater nutrients. Nor are existing models applicable to large numbers of freshwaters across broad spatial extents such as regions or continents. This research aims to increase model performance by exploring three factors that affect the relationship between land use and downstream nutrients in freshwater: the spatial extent for measuring land use, hydrologic connectivity, and the regional differences in both the amount of nutrients and effects of land use on them. We quantified the effects of these three factors that relate land use to lake total phosphorus (TP) and total nitrogen (TN) in 346 north temperate lakes in 7 regions in Michigan, USA. We used a linear mixed modeling framework to examine the importance of spatial extent, ...

流域土地利用格局，尤其是农业与城市用地，长期以来被学界公认为地表水体营养盐浓度的主要驱动因子。然而，目前鲜有能够将流域土地利用规模与下游淡水水体营养盐水平建立关联的简易模型被构建出来，且现有模型亦无法适用于跨区域乃至大陆尺度的海量淡水水体研究。本研究旨在通过剖析影响流域土地利用与下游淡水营养盐关联关系的三类核心因素，提升模型预测性能：即土地利用监测的空间尺度、水文连通性，以及营养盐本底水平与土地利用影响效应的区域差异。我们针对美国密歇根州7个区域内的346个北温带湖泊，量化了这三类因素在土地利用与湖泊总磷（total phosphorus, TP）、总氮（total nitrogen, TN）关联关系中的调控作用，并采用线性混合模型框架，探究空间尺度的重要性……