Influence of coastal groundwater salinization on the distribution and risks of heavy metals

Abstract

Coastal groundwater quality significantly affects the regional sustainable development, due to the water resource shortage in coastal zone. Current studies on coastal groundwater have mainly focused on saline water intrusion and over-extraction. Information on the heavy metal pollution of coastal groundwater with salinization trend is limited. This study investigated heavy metals in groundwater from a typical coastal region with intensive anthropogenic activities and saline water intrusion. The southwestern coastal plains of the study area showed significant groundwater salinization trend. Heavy metals in the coastal groundwater mainly originated from anthropogenic activities and groundwater salinization according to principal component analysis. Relative high concentrations of As, Co, Cr, Cu, Fe, Mn, and Ni occurred in the southwestern coast of the study area with high TDS level, indicating that the concentrations of these heavy metals in shallow aquifer of the study area might be influenced by the groundwater salinization. Average concentrations of heavy metals in groundwater of the study area ranged from 0.03 (Cd) to 686.92 (Fe) μg/L. Fe was the dominant heavy metal in groundwater with the maximal concentration of 2333.76 μg/L and exceeding-standard rate reaching 98.23%. Approximately 13.27% of sampling sites showed moderate or higher heavy metal pollution of groundwater based on heavy metal pollution index. Heavy metals in groundwater exerted low ecological risks. Elements Fe, Ni, and As were the main contributors for ecological risks. Cancer risks of heavy metals for both adults and children were high at all sampling sites. Non-cancer risks for adults and children were unacceptable at 4.42% and 17.70% of sampling sites, respectively. The

Use of Heavy Metal Content and Modified Water Quality Index to Assess Groundwater Quality in a Semiarid Area

“…We used the ecological risk index (ERI) [50,51] to evaluate the potential ecological hazards associated with heavy metals in groundwater. The ecological risk index was calculated as:…”

The effects of high salinity on nitrogen removal and the formation characteristics of aerobic granular sludge

“…The intrusion of seawater caused by excessive groundwater extraction and the rising sea level due to global warming add to the volume of high-salinity wastewater flowing into the sewage treatment plants in coastal areas [1][2][3]. Furthermore, the high-salinity wastewater generated by marine aquaculture and seafood processing industries is known to be a factor impacting the efficient treatment of the contamination sources in established wastewater treatment plants [4,5].…”

Redox Dependent Arsenic Occurrence and Partitioning in an Industrial Coastal Aquifer: Evidence from High Spatial Resolution Characterization of Groundwater and Sediments

“…Numerous environmental conditions can influence As partitioning and need to be considered in a groundwater remediation approach. One such important factor in coastal environments that can significantly influence the behavior of As is groundwater salinity, which influences both groundwater composition and ionic strength [25,26]. For example, elevated electrolyte concentrations may influence the adsorption affinity of As onto the iron oxyhydroxides [27][28][29] and a variety of other sediment properties.…”

“…For example, elevated electrolyte concentrations may influence the adsorption affinity of As onto the iron oxyhydroxides [27][28][29] and a variety of other sediment properties. Seawater intrusion's effect on As adsorption is among the most studied [25,30,31], but it is complicated to predict As partitioning near the groundwater-seawater interface, because chemical variability interacts with density gradients that can give rise to complex hydrological and geochemical processes [32][33][34]. Consequently, understanding As mobility in coastal environments can be extremely challenging.…”