Assessment of water quality in moatize, mozambique: possible human health risks from coal mining and use

Abstract

This study evaluated harmful elements and associated health risks in Moatize, Mozambique's surface and groundwater, aligning with SDGs 3 (good health) and 6 (clean water). During both wet and dry seasons, 30 water samples were collected. Ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄^2-, HCO₃^-, NO₃^-, F^-, and Cl^-) were analyzed using Ion Chromatography (IC), while concentrations of PTEs (Ba, Co, Cr, Cu, Mn, Mo, Pb, Sr, V, U, and Zn) were determined in water, coal, and ash samples by ICP-MS. Results indicated that PTE levels in coal and coal ash exceeded global average trace element concentrations. Moatize's water chemistry is mainly influenced by natural geological processes, especially rock weathering. Most water samples showed Pb and Se levels above the WHO (2021). Guidelines for drinking-water quality (4th ed., incorporating the first and second addenda). World Health Organization and Mozambican Water Quality Limits (MWQL). In surface water, Pb ranged from 0.006 to 0.11 mg/L during the dry season and 0.003-0.11 mg/L during the wet season; groundwater levels ranged from 0.003 to 0.016 mg/L, with two samples exceeding the WHO/MWQL limit of 0.01 mg/L. Se was elevated only in dry season groundwater (0.017-0.022 mg/L), exceeding the MWQL of 0.01 mg/L. The Pollution Index (PI) ranged from low (0) to highly polluted (392.77) due to PTEs. The most common pollutants were Pb > Se > Mn > Cu in dry season surface water and Pb > Se > Cu > Mn in wet season surface water and groundwater. Health risk assessments indicated potential non-carcinogenic issues from oral exposure (HQoral > 1), especially from NO₃^-, Cu, and Se, with children being more vulnerable. Conversely, dermal exposure (HQdermal < 1) did not pose significant health risks for any group.