Heavy metals and major anion content in groundwater of Tamoios coastal district (Rio de Janeiro/Brazil): assessment of suitability for drinking purposes and human health risk

ABSTRACT

The coastal environment of Tamoios District (Rio de Janeiro State, Brazil) has been extensively modified by anthropogenic interference. Activities such as agriculture, livestock, and domestic wastewater discharge, expose groundwater to several toxic chemical elements. Some of these elements may accumulate and affect the potability of the water, making it unsafe for human consumption. Thus, hydrochemical characterisation of Tamoios groundwater was carried out with a variety of methods of representation (Piper Diagram, Hierarchical Clustering Analysis, Spearman’s correlation matrix, and groundwater suitability assessment), comparing six water quality standards and applying Nemerow Pollution Index (NPI). Human health risk assessment of eleven metals (Ba, Co, Cu, Cr, Sr, Mn, Mo, Ni, Zn, Al and V) and two anions (NO₃⁻ and F⁻) was calculated by the Hazard Index, a tool developed by the United States Environmental Protection Agency to establish the potential health risk via chemical exposure in drinking water for adult and child population. Results showed that the concentration of Mn, NO₃⁻, Al and Cr were above the water quality standards for human ingestion. NPI classification defined 20% of the samples as slightly polluted and 40% as severely polluted. The spatial distribution of NPI values demonstrated that the samples neighbouring the coastline did not show excessive levels of heavy metals, NO₃⁻ and F⁻. For both child and adult population, concentration of Co and NO₃⁻ represented a risk to health. In addition, Cr and F⁻ also represented heath risks to child population, the most vulnerable residents. Health risk for heavy metals and anions showed different spatial distribution trends. Poor quality groundwater and simultaneous exposure to different chemical compounds represented a health risk for both child and adult population in the study area.

KEYWORDS:

• Hydrogeochemistry
• drinking water
• health risk assessment
• coastal area

Acknowledgements

The authors would like to thank the Carlos Chagas Filho Foundation for Research Support in the State of Rio de Janeiro (FAPERJ) for the financial support. This research was also supported by the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) with a scholarship funding.

Disclosure statement

The authors declare that they have no conflict of interest.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded by Carlos Chagas Filho Foundation for Supporting Research in the State of Rio de Janeiro (FAPERJ)