A first evaluation of water resource conditions after an environmental reclamation effort at a former degraded coal mining area in Southern Brazil

A decade-long journey shed light on chemical composition and field determination of acid mine drainage in Brazil

Regular monitoring of Acid Mine Drainage (AMD) is essential for understanding its extent and impact on water resources. Traditional manual sampling methods have limitations, such as limited representativeness and delayed lab analysis. High-frequency monitoring offers an alternative, enabling real-time analysis of AMD fluctuations and determination of constituents in the field. This study assessed a decade-long environmental monitoring database from watersheds impacted by coal mining in Brazil to analyze the relationships between physical properties and constituents from different water sources affected by AMD. Samples were grouped into four categories based on location and contamination levels. Results revealed that water samples from the two groups not affected by AMD exhibited near-neutral pH, low metal and sulfate concentrations, and a large portion of samples below the quantification limit for Mn and Al. In contrast, samples from groups affected by AMD displayed high metal and sulfate concentrations and acidic pH, with the highest contamination observed in the underground mine discharges group (AMD UMD). Spearman correlation analyzes between field (pH and electrical conductivity (EC)) and lab (SO42-, Fe, Mn, and Al) parameters showed no significant correlations in non-AMD-affected groups, but significant correlations in AMD-affected groups, particularly the Streams group. A regression model between sulfate and EC was identified as the best predictor for AMD, enabling continuous, low-cost monitoring of contaminated streams and providing insight into previously unobserved AMD processes, such as variations in contamination during storm events and river flushing.

Study of geochemical features of soils on the territory of an abandoned coal mining area using geoinformation technologies

The article describes the results of a study of the geochemical features of soils on the territory of an abandoned mining area. The Kizel coal basin (Russia) is of particular interest for studying the consequences of technogenic and post-technogenic transformation of the natural environment. The study of the soil as a deposit medium made it possible to identify geochemical indicators of the negative impact. Such a detailed study of the distribution of chemical elements in this area was conducted for the first time. Geoinformation system and maps with interpolation were created to study the spatial distribution of metals and metalloids in soils. Umbric Retisols Abruptic and Haplic Retisols Abruptic soils are common in the territory. Sampling for geochemical testing was carried out from two horizons: humus and podzolic. Sampling from two depths made it possible to identify elements that continue to be contaminated at the time of the study. A total of 103 sample plots were established in the study area. The results obtained were compared with the background of the natural region of the Western Urals to identify the contribution of technogenesis. As a result, the coefficients of concentration and dispersion of chemical elements were calculated. Due to this, elements were identified, the accumulation of which occurs on the territory of the Kizelovsky coal basin. To identify the current and accumulated pollution, the ratio between the humus and podzolic horizons was calculated. As a result, it was found that at the moment in the humus horizon in some areas there is a high accumulation of Co, Mn, Ni and Sr. The geochemical series of the territory for the humus and podzolic horizons was obtained: Fe > Ti > Mn > Sr > Cr > V > Zn > Ni > Co > Pb > As. Data on the geochemical specificity of the territory of the Kizel coal basin have been obtained. The created geoinformation database reflects the physical and chemical properties of soils, metals and metalloids content, dispersion and accumulation coefficients, coefficients of the ratio of the humus and podzolic horizon. Based on it, it is possible to obtain data on the geochemical features of the territory, geoecological characteristics, spatial distribution of metals and metalloids and identification of pollution sources. Co (24 ± 2.8 mg/kg), Mn (1100 ± 155 mg/kg), Ni (69 ± 9.3 mg/kg), As (10 ± 3.5 mg/kg), Cr (178 ± 20 mg/kg), Zn (80 ± 7.8 mg/kg) and Sr (221 ± 26 mg/kg) accumulate in the humus horizon. Co (24 ± 1.8 mg/kg), Mn (1000 ± 103 mg/kg), Ni (60 ± 6.4 mg/kg) and Cr (153 ± 15.2 mg/kg) accumulate in the podzolic horizon.