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Six groundwater samples were collected from four aquifers in Renlou coal mine, northern Anhui Province, China, and concentration, temporal variation and speciation of five heavy metals (Cr, Cu, Ni, Pb and Zn) were analyzed. The results of physicochemical parameters and major ions showed that the selected groundwater were representative samples of Quaternary aquifer (QA), coal measure aquifer (CA), Taiyuan limestone aquifer (TA) and Ordovician limestone aquifer (OA). Cr, Ni and Zn increased in the four aquifers from 2002 to 2014, but Pb decreased from 2006 to 2014. Cu concentration increased in QA and TA, but decreased in CA and OA. Although all monitoring results met the standards recommended by WHO and GB5749-2006, Cr and Cu in some groundwater samples exceeded GB/T 14848-93, especially in CA. Soluble metallic hydroxides were the dominant species of heavy metals in QA, while free ions were the main species in TA and OA. Excepted Ni2+ and Zn2+, CuCO3(aq) and PbCO3(aq) were the dominant species of Cu and Pb in CA, respectively, indicating more CO2 had been flooded and dissolved in groundwater from ground atmospheric environment. The enhanced concentration and special dominant species of heavy metals revealed that the ‘closed’ characteristics of CA in Renlou coal mine might have been broken due to coal mining activity.

Knowledge of the environmental background and a baseline are important for local environmental studies and management. In this study, seventy groundwater samples taken near the city of Suzhou, northern Anhui Province, China have been measured for their iron concentrations, and the results processed by geostatistical analytical techniques (including semi-variance, spatial autocorrelation and cluster analyses). The results indicate that the quality of these groundwater samples is relatively good, and all can be classified as class one according to their iron concentrations and the groundwater quality in China. The spatial distribution of iron concentrations shows that they increase from north to south in the area. The semi-variance, spatial autocorrelation and cluster analyses suggest that iron concentrations in the shallow groundwater were affected by combined natural and anthropogenic contributions. After removing the spatial outliers, the environmental baseline of iron in the shallow groundwater in the study area is established as being 0–28.5 μg/l.

Urbanization and related human activities have brought bad effects to the environment, especially shallow groundwater systems in urban areas. In this study, sixty-three shallow groundwater samples in the urban area of Suzhou, northern Anhui Province, China were collected and analyzed for the concentrations of eight heavy metals (Fe, Mn, Zn, Cr, Cd, Cu, Pb and Ni). The results indicate that some of the heavy metals (Zn, Ni, Cr, Cd and Fe) are present below the international drinking water standards but more than half of the sources sampled do not meet the requirements for Mn, Cu and Pb. Quality assessment suggests that all of the samples have heavy metal pollution indices (HPI) lower than 100, implying that they can be used for drinking directly. However, the degrees of contamination (Cd) observed suggest that about one third of the samples are classified as heavily polluted. Heavy densities of population and traffic in the old quarter of the city are considered responsible for the pollution of the groundwater system in the city. Moreover, Cd, Pb, Ni and Mn are identified as metals affected by human activities, whereas Fe, Zn, Cu and Cr are considered to originate from the natural environment, based on the comparison of spatial distributions of HPI, Cd and heavy metal concentrations, as well as factor analysis.

Groundwater is important for either resource usage or safety of coal mining in north China. In this study, concentrations of eight kinds of heavy metals (Pb, Cd, Cu, Ni, Cr, Zn, Fe and Mn) in groundwater from three deep aquifers in the Wolonghu coal mine, northern Anhui Province, China have been analyzed for water quality assessment and water source identification. The results suggest that the groundwater have different concentrations of heavy metals among aquifers, which might be the results of different occurrence forms of heavy metals (e.g. Pb, Cd, Cu and Cr were adsorbed by iron hydroxides) and different kinds of water rock interactions (e.g. Mn and Zn originated from carbonate rocks). In comparison with the groundwater quality standard of China and WHO, most of them cannot be used for drinking directly but must be treated before drinking, especially the Pb, Cd and Fe contents. Moreover, hydraulic connection between aquifers has been identified by plots of factor scores and cluster analysis, which is similar to the results obtained by previous studies. Moreover, discriminant analysis demonstrated that heavy metals can be used for identification the source of inrush water in coal mines.