Spatiotemporal variation of nitrogen and phosphorus and its main influencing factors in Huangshui River basin

Biqiong Dong,Shanshan Liu,Jianming Feng,Tianling Qin,Chenhao Li,Xin Zhang,Yan Zhao,Yu Wang

doi:10.1007/s10661-021-09067-1

Abstract

The foundation of managing excess nutrients in river is the identification of key physical processes and the control of decisive influencing factors. The existing studies seldom consider the influence of rainfall-runoff relationship and only focus on a few anthropogenic activities and natural attributes factors. To address this issue, a comprehensive set of influencing factors including rainfall-runoff relationship (represented by runoff coefficient), basic physical and chemical parameters of water quality, land use types, landscape patterns, topography, and socioeconomic development was constructed in this study. M–K test and cluster analysis were conducted to identify the temporal mutation and spatial clustering characteristics of NH3-N and TP in Huangshui River basin, respectively. Partial least squares regression was used to elucidate the linkages between water contaminants and the factors. As shown in the results, the temporal mutations of NH3-N and TP were obvious in the middle reaches, with 4 out of 7 catchments in the middle reaches have a larger number of mutations of NH3-N than other catchments. The cluster analysis results of NH3-N and TP among catchments were similar. This study also indicated that although the Huangshui River basin was located in the upper reaches of the Yellow River, the influences of rainfall-runoff relationship on spatiotemporal changes of NH3-N and TP in its sub-basins were limited. Only the temporal change of NH3-N in Jintan catchment in the upstream area was significantly affected by runoff coefficient. The indexes of proportion of water area (PWA), proportion of impervious area (PIA), and proportion of primary industry (PPI) were the top three influencing factors of temporal variation of NH3-N and TP for most catchments in the middle reaches. The temporal change of NH3-N in Jintan catchment in the upstream area was obviously affected by runoff coefficient. The spatial variation of NH3-N and TP were all affected by PWA and proportion of secondary industry significantly. The results of this study can provide theoretical basis and technical support for the control and management of nitrogen and phosphorus pollution in upper reaches of rivers.

Highlights

Prevention and control of river nitrogen and phosphorus pollution is one of the key issues to achieve sustainable river basin planning and management (Reichwaldt & Ghadouani, 2016; Srinivas et al, 2020)
4 out of 7 catchments in the middle reaches of the Huangshui River basin were found to have a larger number of mutations of NH3-N (>4) through the M–K test
The cluster analysis results of N H3-N and total phosphorus (TP) of all catchments were similar according to hierarchical agglomerative cluster analysis

Summary

Introduction

Prevention and control of river nitrogen and phosphorus pollution is one of the key issues to achieve sustainable river basin planning and management (Reichwaldt & Ghadouani, 2016; Srinivas et al, 2020). The relative importance of different influencing factors varies in different studies especially for the upper reaches of rivers. To identify the main influencing factors which affect the spatiotemporal variation of nitrogen and phosphorus in the upper reaches of rivers, it is essential to analyze based on key physical processes. The spatiotemporal variation of nitrogen and phosphorus in riverine water is driven by three key processes (Guo et al, 2019) (Fig. 1): (1) Source: the amount of the constituent within the catchment. Different land use types and socioeconomic development factors (such as the distribution of population, livestock and gross regional domestic product) are related to source and load of nitrogen and phosphorous

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Conclusion