Ammonium Nitrogen Streamflow Transport Modelling and Spatial Analysis in Two Chinese Basins

Jingchen Yin,Haitao Chen,Yuqiu Wang,Puzhou Wang,Guoguang Li,Lifeng Guo

doi:10.3390/w14020209

Abstract

Ammonium nitrogen (NH4+-N), which naturally arises from the decomposition of organic substances through ammonification, has a tremendous influence on local water quality. Therefore, it is vital for water quality protection to assess the amount, sources, and streamflow transport of NH4+-N. SPAtially Referenced Regressions on Watershed attributes (SPARROW), which is a hybrid empirical and mechanistic modeling technique based on a regression approach, can be used to conduct studies of different spatial scales on nutrient streamflow transport. In this paper, the load and delivery of NH4+-N in Poyang Lake Basin (PLB) and Haihe River Basin (HRB) were estimated using SPARROW. In PLB, NH4+-N load streamflow transport originating from point sources and farmland accounted for 41.83% and 32.84%, respectively. In HRB, NH4+-N load streamflow transport originating from residential land and farmland accounted for 40.16% and 36.75%, respectively. Hence, the following measures should be taken: In PLB, it is important to enhance the management of the point sources, such as municipal and industrial wastewater. In HRB, feasible measures include controlling the domestic pollution and reducing the usage of chemical fertilizers. In addition, increasing the vegetation coverage of both basins may be beneficial to their nutrient management. The SPARROW models built for PLB and HRB can serve as references for future uses for different basins with various conditions, extending this model’s scope and adaptability.

Highlights

An excess of nutrients, which are generated from point and non-point sources and are eventually transported to water bodies, has led to severe eutrophication throughout the world in recent years [1]
Ammonium nitrogen (NH4+-N), which naturally arises from the decomposition of organic substances through ammonification, is a critical nutrient produced by human activities such as fertilizing, livestock breeding, and municipal wastewater treating
This study developed SPAtially Referenced Regressions on Watershed attributes (SPARROW) models in two multi-rivers basins in China, which cover large areas in the north and south of China, respectively

Summary

Introduction

An excess of nutrients, which are generated from point and non-point sources and are eventually transported to water bodies, has led to severe eutrophication throughout the world in recent years [1]. Eutrophication of water bodies causes toxic algal blooms, oxygen depletion, loss of biodiversity, and thereby, the degradation of water quality and aquatic ecosystem services [2]. Synthetic nitrogen fertilizers are slightly absorbed by crops (about 10%), while large quantities of synthetic nitrogen are exported to aquatic systems through surface runoff and decomposed to NH4+-N [3]. Domestic and industrial wastewater are important manners, by which NH4+-N enters into aquatic systems. Excessive NH4+-N leads to eutrophication, endangering aquatic species and polluting water sources [4]. Since NH4+-N has a tremendous influence on local water quality, it is vital for water quality protection to assess the amount, sources, and transport of NH4+-N [5]

Methods

Results

Discussion

Conclusion