[Identifying Relationship Between Nutrient Contents in Road-Deposited Sediment and Urban Basic Elements Based on...

Understanding the spatial connection between urban basic elements and pollutants in road-deposited sediment (RDS) is beneficial to the quantitative explanation of source areas and the precise management of urban nonpoint source pollution. The objective of this study was to explore the spatial connection between urban basic elements and nutrient contents in RDS, using Hanyang district of Wuhan city as a case study area. Total nitrogen (TN), total phosphorus (TP), exchangeable phosphorus (Ex-P), aluminum-bound phosphorus (Al-P), iron-bound phosphorus (Fe-P), occluded phosphorus (Oc-P), apatite phosphorus (Ca-P), detrital apatite phosphorus (De-P), and organophosphorus (Or-P) were chosen as representative pollutants, using the kernel density of the road network and seven groups of points of interest to represent the spatial distribution of urban basic elements. Through correlation analysis, the relationship between urban basic elements and nutrient contents in RDS was examined. The results showed that nutrient contents in RDS from Hanyang varied significantly with location. Specifically, Al-P, Oc-P, and Or-P had greater spatial variability in contrast with that of Ex-P and Fe-P, and the spatial variabilities of Ca-P and De-P both varied considerably with the particle size of the RDS. All types of urban basic elements and nutrient contents in RDS were correlated to different extents. Ex-P, Al-P, Oc-P, and Or-P were negatively correlated with the kernel density of most urban basic elements, whereas TN, TP, Fe-P, Ca-P, and De-P showed a positive correlation with the kernel density of most urban basic elements. TN, Al-P, Fe-P, Ca-P, and Or-P appeared to have much stronger correlation with the kernel density of urban basic elements compared to other selected pollutants, whereas the extent of correlation between them was influenced by the particle size of the RDS. In general, the correlation between nutrient contents in RDS and the kernel density of urban basic elements was more significant when the particle size of the RDS was under 450 μm and more robust when the particle size of the RDS was under 150 μm.