Identification of Groundwater Contamination in a Rapidly Urbanized Area on a Regional Scale: A New Approach of Multi-Hydrochemical Evidences.

Pan Bi,Dongya Han,Guanxing Huang,Lixin Pei,Jiangmin Song

doi:10.3390/ijerph182212143

Abstract

Efficient identification of groundwater contamination is a major issue in the context of groundwater use and protection. This study used a new approach of multi-hydrochemical indicators, including the Cl-Br mass ratio, the hydrochemical facies, and the concentrations of nitrate, phosphate, organic contaminants, and Pb in groundwater to identify groundwater contamination in the Pearl River Delta (PRD) where there is large scale urbanization. In addition, the main factors resulting in groundwater contamination in the PRD were also discussed by using socioeconomic data and principal component analysis. Approximately 60% of groundwater sites in the PRD were identified to be contaminated according to the above six indicators. Contaminated groundwaters commonly occur in porous and fissured aquifers but rarely in karst aquifers. Groundwater contamination in porous aquifers is positively correlated with the urbanization level. Similarly, in fissured aquifers, the proportions of contaminated groundwater in urbanized and peri-urban areas were approximately two times that in non-urbanized areas. Groundwater contamination in the PRD was mainly attributed to the infiltration of wastewater from township-village enterprises on a regional scale. In addition, livestock waste was also an important source of groundwater contamination in the PRD. Therefore, in the future, the supervision of the wastewater discharge of township-village enterprises and the waste discharge of livestock should be strengthened to protect against groundwater contamination in the PRD.

Highlights

Groundwater resources are important sources of industrial, agricultural, and domestic water, especially in urbanized areas where there is an ever-increasing demand for water [1].many human activities, such as urban expansion and agricultural activities, lead to the deterioration of groundwater quality primarily due to infiltration from domestic sewage, industrial wastewater, landfill leachate, and fertilizers used on agricultural lands [2]
The contaminated groundwater in the Pearl River Delta (PRD) was identified by six indicators, including the Cl/Br ratio, the NO3 facies, the concentrations of NO3 −, PO4 3−, organic contaminants, and Pb in groundwater
Note that the Cl/Br ratio was combined with high levels of NH4 +, Na, and NO3 − for identifying contaminated groundwater in porous aquifers, fissured aquifers, and karst aquifers, respectively

Summary

Introduction

Groundwater resources are important sources of industrial, agricultural, and domestic water, especially in urbanized areas where there is an ever-increasing demand for water [1].many human activities, such as urban expansion and agricultural activities, lead to the deterioration of groundwater quality primarily due to infiltration from domestic sewage, industrial wastewater, landfill leachate, and fertilizers used on agricultural lands [2]. Groundwater resources are important sources of industrial, agricultural, and domestic water, especially in urbanized areas where there is an ever-increasing demand for water [1]. The identification of anthropogenic contributions to groundwater contamination is a major issue in the context of the use and management of groundwater resources in urbanized areas. The Pearl River Delta (PRD) is one of the most rapidly urbanized and industrialized areas in China. The area occupied by construction land in the PRD in 2006 was more than two times that in 1988 [3]. In this case, groundwater resources become more important in the PRD because of the ever-increasing water demand with the population

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Conclusion