Abstract

Groundwater quality problems have emerged in many geographical areas due to natural environmental processes and human intervention in the geosystems. Hydrogeochemical appraisal of fluoride contaminated groundwater in Qinkenpao area, Daqing State, China is carried out by means of groundwater quality investigations. Results obtained from aqueous speciation modeling using AQUACHEM 5.1 reveal that the groundwater is undersaturated with fluorite and with calcite. The samples also contained high concentrations of nitrate, which is a serious water quality issue due to the impact of human activity. Factor analysis modeling demonstrated that NO₃⁻ in the system are produced by anthropogenic sources. Strong correlation observed between NO₃⁻ and Ca²⁺, Mg²⁺, Cl⁻ and F⁻, suggesting that they have the same origin. The factor analysis indicates that sodium plus nitrate bicarbonate groundwater have a high loading factor for fluoride, whereas that for calcium chloride and magnesium chloride groundwater is low. The plausible geochemical reactions in the area of study are dissolution of calcite and dolomite, carbon dioxide and sulphate minerals with ion exchange.

Key words: Aqueous speciation modeling, fluoride, nitrate, groundwater, hydrogeochemical, factor analysis.