Assessment of major ions and heavy metals in groundwater: a case study from Guangzhou and Zhuhai of the Pearl River Delta, China

Abstract

Anthropogenic activities in the Pearl River Delta (PRD) have caused a deterioration of groundwater quality over the past twenty years as a result of rapid urbanization and industrial development. In this study, the hydrochemical characteristics, quality, and sources of heavy metals in the groundwater of the PRD were investigated. Twenty-five groundwater samples were collected and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), δ 18 O, δ 2 H, major ions, and heavy metals. The groundwater was slightly acidic and presented TDS values that ranged from 35.5 to 8,779.3 mg$L -1 . The concentrations of the major ions followed the order Cl -> HCO -Ca-Mg-HCO 3 and Na-K-HCO 3 were the predominant types of facies, and the chemical composition of the groundwater was primarily controlled by chemical weathering of the basement rocks, by mixing of freshwater and seawater and by anthropogenic activities. The heavy metal pollution index (HPI) indicated that 64% of the samples were in the low category, 16% were in the medium category and 20% were in the high category, providing further evidence that this groundwater is unsuitable for drinking. Lead, arsenic, and manganese were mainly sourced from landfill leachate; cadmium from landfill leachate and agricultural wastes; mercury from the discharge of leachate associated with mining activities and agricultural wastes; and chromium primarily from industrial wastes. According to the irrigation water quality indicators, the groundwater in the PRD can be used for irrigation in most farmland without strong negative impacts. However, approximately 9 million people in the Guangdong Province are at risk due to the consumption of untreated water. Therefore, we suggest that treating the groundwater to achieve safer levels is necessary.

Human exposure risk to heavy metals through groundwater used for drinking in an intensively irrigated river delta

“…These industries dispose the treated/partially treated wastewater that do/do not meet the standards in the surface water bodies such as rivers, lakes, ponds and into the sea in coastal areas. Contamination due to suite of heavy metals is also commonly reported around landfills (Bakis and Tuncan 2011;Lu et al 2016). The other important contamination route is through excessive application of agrochemicals that are retained in the unsaturated zone and reach groundwater through irrigation return flow.…”

“…Accumulation of the bio-toxic heavy metals in crops and subsequent transport in the food chain pose potential risk to human health. Hence, several studies have been conducted on these lines (Nouri et al 2008;Wongsasuluk et al 2014;Lu et al 2016).…”

Chemical and Statistical Studies on Water and Stream Sediments Around the Coal Mine Area in Dazhu, China

“…In the field of environmental science, the multivariate analysis has become a more powerful tool than the classical single variable method as it makes data analysis easier (Hou et al, 2017). Multivariate analysis methods, such as principal component analysis (PCA) and factor analysis (FA) have been successfully applied to assess the quality of the water and the stream sediment to identify the chemical processes therein (Qin et al, 2019;Narváez et al, 2007;Mostert et al, 2010;Atulya et al, 2017;Lu et al, 2016).…”

Arsenic in the Pearl River Delta and its related waterbody, South China: occurrence and sources, a review

“…Sampling strategies and analytical methods used for the determination of As concentration vary, depending on the sample location/medium and the purposes of respective investigations. For groundwater, samples were usually collected from available/functional wells in the study area (Liu et al 2014;Lu et al 2016;Huang et al 2013Huang et al , 2018a. However, in certain cases, fresh boreholes were also drilled .…”