Tu Jun
Department of Geography and Anthropology, Kennesaw State University, 402 Bartow Ave, Kennesaw, GA, 30144, USA.
Environ Sci Pollut Res Int. 2023 Sep;30(41):94694-94720. doi: 10.1007/s11356-023-29038-y. Epub 2023 Aug 4.
Roads and traffic are important elements of urbanization, but their spatial associations with surface water quality in watersheds have been seldom studied. In this study, the spatially varying associations of three urbanization indicators, including road density, traffic density, and percentages of urban land, with twenty water quality indicators, including dissolved oxygen (DO), specific conductance (SC), dissolved solids (DS), suspended solids (SS), biochemical oxygen demand (BOD), dissolved nutrients, dissolved ions, heavy metals, and coliform bacteria, across the watersheds in the northern part of the state of Georgia, USA, have been examined by a conventional statistical method, ordinary least squares regression (OLS), and a spatial statistical method, geographically weighted regression (GWR). The results from OLS show that the urbanization indicators all have significant positive associations with the majority of the studied water pollutants, indicating that water pollution is significantly contributed by human activities related to urbanization in northern Georgia. In contrast, GWR results show that the associations vary across the watersheds affected by their urbanization levels. Significant positive associations are found between each urbanization indicator and each of the studied water pollutants, but not in all watersheds. The associations of suspended solids, nitrogen nutrients, and coliform bacteria with all three urbanization indicators are more significant in less-urbanized watersheds, while the associations of dissolved ions, BOD, and orthophosphate (PO) with road density and traffic density are more significant than those with urban land in more-urbanized watersheds, indicating that those water pollutants are more contributed by human activities associated with roads and traffic than other activities in more-urbanized areas. As a pilot study to explore how and why the associations of surface water quality with roads and traffic change across watersheds with different urbanization levels, its findings suggest that the policies of watershed management, land-use planning, and transportation planning should be tailored in local areas based on the locally important water pollutants and their associated urbanization indicators.
道路和交通是城市化的重要组成部分，但它们与流域地表水水质的空间关联却鲜有研究。在本研究中，运用传统统计方法普通最小二乘法回归（OLS）和空间统计方法地理加权回归（GWR），考察了美国佐治亚州北部流域内道路密度、交通密度和城市土地百分比这三个城市化指标与溶解氧（DO）、电导率（SC）、溶解固体（DS）、悬浮固体（SS）、生化需氧量（BOD）、溶解养分、溶解离子、重金属和大肠菌群等20个水质指标之间的空间变化关联。OLS结果表明，城市化指标与大多数研究的水污染物均呈显著正相关，这表明佐治亚州北部与城市化相关的人类活动对水污染有显著影响。相比之下，GWR结果显示，这些关联在受城市化水平影响的不同流域间存在差异。虽然各城市化指标与各研究水污染物之间均存在显著正相关，但并非在所有流域都是如此。在城市化程度较低的流域，悬浮固体、氮养分和大肠菌群与所有三个城市化指标的关联更为显著；而在城市化程度较高的流域，溶解离子、BOD和正磷酸盐（PO）与道路密度和交通密度的关联比与城市土地的关联更为显著，这表明在城市化程度较高的地区，这些水污染物更多是由与道路和交通相关的人类活动造成的，而非其他活动。作为一项探索地表水水质与道路和交通的关联如何以及为何在不同城市化水平的流域间发生变化的试点研究，其结果表明，流域管理、土地利用规划和交通规划政策应根据当地重要的水污染物及其相关的城市化指标进行因地制宜的制定。
