Hydrochemical characteristics of mine waters from abandoned mining sites in Serbia and their impact on surface water quality

Assessing the geochemical processes controlling groundwater quality and their possible effect on human health in Patna, Bihar

This research was conducted in the urban area of Patna region, the capital and largest city of Bihar, which is part of the Indo-Gangetic alluvium plain. This study aims to identify the sources and processes controlling groundwater's hydrochemical evolution in the Patna region's urban area. In this research, we evaluated the interplay between several measures of groundwater quality, the various possible causes of groundwater pollution, and the resulting health risks. Twenty groundwater samples were taken from various locations and examined to determine the water quality. The average EC of the groundwater in the investigated area was 728 ± 331.84 µS/cm, with a range of around 300-1700 µS/cm. Positive loadings were seen for total dissolved solids (TDS), electrical conductivity (EC), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), chloride (Cl-), and sulphate (SO42-) in principal component analysis (PCA), demonstrating that these variables accounted for 61.78% of the total variance. In the groundwater samples, the following main cations are the most prevalent such as Na+  > Ca2+  > Mg2+  > K+, while the dominant anions are HCO3-  > Cl-  > SO42-. The elevated HCO3- and Na+ ions indicate that carbonate mineral dissolution might affect the study area. The result demonstrated that 90% of samples fall into the Ca-Na-HCO3 type, remaining in the mixing zone. The presence of the NaHCO3 kind of water is suggestive of shallow meteoric water, which may have originated from the river Ganga that is located nearby. The results show that a multivariate statistical analysis and graphical plots successfully identify the parameters controlling groundwater quality. In accordance with guidelines for safe drinking water, the electrical conductivity and potassium ion concentrations in the groundwater samples are 5% higher than acceptable levels. People who take large amounts of salt replacements report feeling tight in the chest, vomiting, having diarrhoea, developing hyperkalaemia, having trouble breathing, and even experiencing heart failure.

Both natural and anthropogenic factors control surface water and groundwater chemistry and quality in the Ningtiaota coalfield of Ordos Basin, Northwestern China

An understanding of the vertical variations in hydrogeochemical processes in various aquifers and quality suitability assessment is crucial for the utilization of groundwater in the Ningtiaota coalfield of Ordos Basin, Northwestern China. Based on 39 water samples collected from surface water (SW), Quaternary pore water (QW), weathered fissure water (WW), and mine water (MW), we conducted self-organizing maps (SOM) algorithm, multivariate statistical analysis (MSA), and classical graphical methods to elucidate the mechanisms controlling the vertical spatial variations in SW and groundwater chemistry and conducted a health risk assessment. The findings indicated that the hydrogeochemical type showed a transition from the HCO₃^--Na⁺ type in SW to the HCO₃^--Ca²⁺ type in QW, then to the SO₄^2--Mg²⁺ type in WW, and back to HCO₃^--Na⁺ type in MW. Water-rock interaction, silicate dissolution, and cation exchange were the main hydrogeochemical processes in the study area. Additionally, groundwater residence time and mining operations were critical external factors that affect water chemistry. Contrary to phreatic aquifers, confined aquifers featured greater circulation depth, water-rock interactions, and external interventions leading to worse quality and higher health risks. Water quality surrounding the coalfield was poor, causing it to be undrinkable, with excessive SO₄^2-, arsenic (As), and F^-, etc. Approximately 61.54% of SW, all of QW, 75% of WW, and 35.71% of MW can be used for irrigation.

Bacterial, Archaeal, and Eukaryote Diversity in Planktonic and Sessile Communities Inside an Abandoned and Flooded Iron Mine (Quebec, Canada)

Abandoned and flooded ore mines are examples of hostile environments (cold, dark, oligotrophic, trace metal) with a potential vast diversity of microbial communities rarely characterized. This study aimed to understand the effects of depth, the source of water (surface or groundwater), and abiotic factors on the communities present in the old Forsyth iron mine in Quebec (Canada). Water and biofilm samples from the mine were sampled by a team of technical divers who followed a depth gradient (0 to 183 m deep) to study the planktonic and sessile communities’ diversity and structure. We used 16S/18S rRNA amplicon to characterize the taxonomic diversity of Bacteria, Archaea, and Eukaryotes. Our results show that depth was not a significant factor explaining the difference in community composition observed, but lifestyle (planktonic/sessile) was. We discovered a vast diversity of microbial taxa, with taxa involved in carbon- and sulfur-cycling. Sessile communities seem to be centered on C1-cycling with fungi and heterotrophs likely adapted to heavy-metal stress. Planktonic communities were dominated by ultra-small archaeal and bacterial taxa, highlighting harsh conditions in the mine waters. Microbial source tracking indicated sources of communities from surface to deeper layers and vice versa, suggesting the dispersion of organisms in the mine, although water connectivity remains unknown.

Hydrochemistry of groundwater contaminated by petroleum hydrocarbons: the impact of biodegradation (Vitanovac, Serbia)

Aquifer contamination by petroleum hydrocarbons leads to measurable changes of groundwater hydrochemistry, primarily due to the microbiological activity. This study analyzes this phenomenon at an historical kerosene-contaminated site in Vitanovac (central Serbia). Due to the long-term hydrocarbon contamination and exposure to aerobic and anaerobic biodegradation mechanisms, the lowest concentrations of O₂, NO₃^-, and SO₄^2- (electron acceptors) and the highest concentrations of Mn and Fe (products of microbial metabolic activity) overlap. The terminal redox-accepting processes in groundwater ranged from oxygen reduction to sulfate reduction. The most anoxic processes were registered in piezometers closest to the source of contamination, as was also confirmed by the redox potential (Eh) measurements. High electrical conductivity values and the highest TOC, SiO₂, and Al concentrations also overlap in the contaminated zone close to the source of contamination. Scanning electron microscopy study of quartz grains from the zone undergoing the impact of biodegradation confirmed the occurrence of weathering microscale processes on mineral surfaces. Taking all these factors together, it seems reasonable to assume that microbiological activity has caused the enhanced weathering of silicate minerals.

Assessment of spa mineral water quality from Vrnjačka Banja, Serbia: geochemical, bacteriological, and health risk aspects

The goal of this study is to evaluate the quality of seven natural mineral water sources in the Vrnjačka Banja area used in the treatment of various diseases. The 24 macro- and microelements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that element content was within allowed limits of concentration, except for B, As, and Se. The evaluated content of these elements can be associated with geological and anthropogenic factors. The sample S6 contains more than twice the concentration of As, meaning that the use of water from this source should be limited due to the negative impact of this element on human health. The calculated values of weekly (EWI) and oral (OI) intakes as well as the acute hazard quotient (HQ_A) of selected toxic and potentially toxic elements indicate no health risks to the consumers. The highest hazard quotient (HQ_L) observed for As in sample S6 (2.0·10^-1) demonstrated a significant risk of carcinogenic diseases in long-term consumption from this source. The estimated non-carcinogenic (DI_A) and carcinogenic (DI_L) dermal intakes with acute (HQ_A) and long-term (HQ_L) hazard quotient values for sample S3 show that there is no health risk to those who use the water from this thermal source for bathing. The presence of aerobic mesophilic bacteria at 22 °C and 37 °C in samples S3, S6, and S7 as well as sulphite-reducing Clostridia species in sample S5 were detected, potentially indicating some non-faecal or faecal contamination.

Multi-Seam Coal Deposit Modeling via Principal Component Analysis & GIS

Spatial modeling and evaluation is a critical step for planning the exploitation of mineral deposits. In this work, a methodology for the investigation of a multi-seam coal deposit spatial variability is proposed. The study area includes the Klidi (Florina, Greece) multi-seam lignite deposit which is suitable for surface mining. The analysis is based on the original data of 76 exploratory drill-holes in an area of 10 km2, in conjunction with the geological and geomorphological data of the deposit. The analytical methods include drill-hole data analysis and evaluation based on an appropriate algorithm, principal component analysis and geographic information techniques. The results proved to be very satisfactory for the explanation of the maximum variance of the initial data values as well as the identification of the deposit structure and the optimum planning of mine development. The proposed analysis can be also helpful for minimizing cost and optimizing efficiency of surface mining operations. Furthermore, the provided methods could be applied in other areas of geosciences, indicating the theoretical value as well as the important practical implications of the analysis.

Consumption of water from ex-mining ponds in Klang Valley and Melaka, Malaysia: A health risk study

Evaluation of health risks due to heavy metals exposure via drinking water from ex-mining ponds in Klang Valley and Melaka has been conducted. Measurements of As, Cd, Pb, Mn, Fe, Na, Mg, Ca, and dissolved oxygen, pH, electrical conductivity, total dissolved solid, ammoniacal nitrogen, total suspended solid, biological oxygen demand were collected from 12 ex-mining ponds and 9 non-ex-mining lakes. Exploratory analysis identified As, Cd, and Pb as the most representative water quality parameters in the studied areas. The metal exposures were simulated using Monte Carlo methods and the associated health risks were estimated at 95th and 99th percentile. The results revealed that As was the major risk factor which might have originated from the previous mining activity. For Klang Valley, adults that ingested water from those ponds are at both non-carcinogenic and carcinogenic risks, while children are vulnerable to non-carcinogenic risk; for Melaka, only children are vulnerable to As complications. However, dermal exposure showed no potential health consequences on both adult and children groups.