The Driving Forces of Point Source Wastewater Emission: Case Study of COD and NH4-N Discharges in Mainland China.

Zhaofang Zhang,Dagmawi Mulugeta Degefu,Juqin Shen,Liang Yuan,Yang Kong,Min An,Chengcai Zhang,Jin Huang,Weijun He,Xin Gao

doi:10.3390/ijerph16142556

Abstract

Excess consumption of water resources and environmental pollution have become major challenges restricting sustainable development in China. In order to prevent the pollution of water resources, policymakers should have reliable emission reduction strategies. This paper aims to contribute new knowledge by analyzing the spatial-temporal characteristics and driving forces of point source emission. The chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) emission variations in 31 provinces and municipalities of mainland China during the years 2004–2017 are analyzed. The results obtained using the logarithmic mean Divisia index (LMDI) method indicate that: (1) the COD and NH4-N emission effects have similar temporal characteristics. Technology improvement and pollutant emission intensity are the main factors inhibiting the incremental COD and NH4-N emission effects, while economic development is the main driving factor of COD and NH4-N emission effects. Population increases play a relatively less important role in COD and NH4-N emission effects. (2) The spatial features of COD and NH4-N emission effects show differences among provinces and municipalities. The reduction of COD emission effects in each province and municipality is obviously better than that of NH4-N emissions. (3) In the eastern, central, and the western regions of China, the total COD emission effect shows a downward trend, while apart from the central region, the NH4-N emission effect appears to be rising in the east and west of China. Therefore, increasing investment into pollution treatment, promoting awareness of water conservation, strengthening technological and financial support from the more developed eastern to the less developed central and western regions, can help to reduce the COD and NH4-N emissions in China.

Highlights

China is the largest developing and fastest growing country [1,2]
The logarithmic mean Divisia index (LMDI) method was used to decompose the effects of the main determining factors of point source chemical oxygen demand (COD) and NH4 -N pollution in mainland China from 2004 to 2017
The four main emission influencing factors are taken into account

Summary

Introduction

China is the largest developing and fastest growing country [1,2]. The population, industrialization and urbanization rate have increased rapidly and caused large wastewater emissions which have become a major environmental concern [3,4]. According to the 2018 China Water Resources Bulletin, the I~III quality level of rivers comprise 78.5% of the total 245,000 km of the river network in China, whereas rivers worse than the V level account for 8.3%. 26.0%, while IV~V lakes account for 74% Chemical oxygen demand (COD) and ammonia nitrogen (NH4 -N) have become the main. Res. Public Health 2019, 16, 2556; doi:10.3390/ijerph16142556 www.mdpi.com/journal/ijerph

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