Quantifying the factors controlling groundwater fluoride and associated health risks in the coastal river delta, northern China

Abstract

Chronic exposure to high fluoride (F-) groundwater has a detrimental effect on the health of hundreds of millions of individuals worldwide. High F- groundwater in coastal areas is frequently observed, but the extent to which various factors influence the distribution of F- concentrations and the health hazards posed to different populations by consuming this groundwater have not been widely documented. In this study, 207 groundwater samples were acquired from the shallow and deep aquifers in the Luanhe River Delta, with an aim to investigate controlling factors and health hazards associated with groundwater F-. In the shallow aquifers, high F- groundwater was mainly determined by mineral dissolution and precipitation, desorption and competitive adsorption, and cation exchange, with relative contributions of 93.6%, 3.8%, and 2.2% respectively. The evaporation and seawater intrusion had little influence on groundwater F- enrichment. With respective contributions of 55.9%, 32.4%, 9.2%, and 2.5%, mineral dissolution and precipitation, desorption and competitive adsorption, geothermal waters, and cation exchange jointly regulated the distribution of groundwater F- in the deep aquifers. The health risk assessments showed that shallow groundwater F- through oral intake and dermal contact posed health hazards to 61.1% of infants, 38.9% of children, 26.7% of adult females and 31.1% of adult males, while in deep groundwater, these percentages were 66.4%, 32.8%, 22.1% and 28.7%, respectively. The present study provides a significant contribution towards enhancing the comprehension of the evolution of groundwater F- in coastal regions, and thereby, establishes a sound scientific basis for the effective management of drinking water.