Reconciliation of Spatiotemporal Influences on Two-Dimensional Distribution and Fate of Emerging Contaminants in a Subtropical River

This study involves elucidation of spatial and temporal influences on horizontal and vertical distribution and fate of contaminants of emerging concerns (CECs) in riverain systems. In total, 23 CECs encompassing antibiotics, nonantibiotic drugs, and bisphenol analogues were detected. The antibiotic concentrations were relatively higher in deep water than in surface water. Spatial connectivity and spatial autocorrelation suggested the occurrence and concentration of the majority of the CECs devoid of neighboring site influences, owing to shorter correlation lengths than the average distances between the sampling sites, hence indicating the localized distribution of CECs in surface water. The PCA biplot indicated that bisphenol A and methyl paraben were mainly responsible for the seasonal variations. Both negative and positive correlations existed between CECs and the environmental parameters to cause temporal variations in CEC contaminants. Spatial structure analysis by singular vector decomposition (SVD) analysis was used to measure the sitewise contribution of CECs. The results indicated relatively higher CEC contaminants and deteriorated water quality in the downstream sites rather than in the upstream sites. This study effectively demonstrated the use of different chemometric techniques for in-depth understanding of various spatial and temporal influences on the fate and horizontal and depth distribution of CECs in riverain systems.