Assessment of Mine Water Quality Using Heavy Metal Pollution Index in a Coal Mining Area of Damodar River Basin, India

The leaching behavior of heavy metal from contaminated mining soil: The effect of rainfall conditions and the impact on surrounding agricultural lands

Contaminated mining soils could lead to heavy metal pollution of surrounding farmlands under rainfall conditions. With the aids of sequential extraction, batch leaching, and dynamic leaching experiments, this study was carried out to investigate the characteristics of heavy metals in contaminated mining soils, understand their leaching behavior under different rainfall conditions, and evaluate the potential effects on surrounding farmlands. The results indicated that the concentrations of heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) in the contaminated mining soils were several or even twenty times higher than their corresponding background values, and Cd, Zn, Cu and Pb had considerable proportions (>50 %) in mobile forms. The leaching amounts of heavy metals from the contaminated mining soils had positive correlation with their contents in acid soluble form, and showed strong dependence on rainfall pH conditions. Acid rainfalls (pH = 4.32) can greatly increase the average annual release of Cd, Zn, Cu and Pb from mine soils in the study area, with increments ranging from 72.4 % (Pb) to 85.9 % (Cd) compared to those under alkaline conditions (pH = 7.42). The leaching of heavy metals was well fitted by two-constant, pseudo second-order and parabolic equations, indicating that their multi-layer sorption/desorption behavior on soil surface was dominated by chemical processes and their release was controlled by the diffusion within the soil pore channels. The two-column leaching experiment showed that the metal-rich leachate can lead to obvious increments of heavy metals in non-residual fractions (in particular Cd in acid soluble form) in surrounding farmlands, which would significantly raise the potential ecological risk associated with heavy metals. These findings indicate the importance of contaminated mining soils as a long-term source of heavy metals and the needs for mitigating the releases of toxic elements, especially in areas with heavy acid precipitation.

Potentially toxic elements contamination in the water resources: an integrated risk assessment approach in the upper Citarum watershed area

The Citarum watershed is West Java Province's most important water resource; hence, harmful compounds should be monitored regularly. This study assessed pollution levels along with ecological and health risks from Cd, Pb, Mn, Fe, Cu, Cr, and Hg contamination in river water, sediment, groundwater, and soil in Citarum's upper watershed. In river water, the average amounts of Cd, Pb, Mn, Fe, Cu, Cr, and Hg were 0.002, 0.05, 0.092, 0.649, 0.022, 0.001, and 0.421 mg/L. In sediment, they were 7.4, 1175.1, 32,289.9, 37.3, 3.9, and 0.015 mg/kg. The mean concentrations of Cd, Pb, Mn, Fe, Cu, Cr, and Hg in groundwater were 0.004, 0.046, 0.567, 0.366, 0.019, 0.001, and 0.177 mg/L, and in soil, BDL, 10.2, 744.6, 50,094.1, 45.6, 5.9, and 0.015 mg/kg. The river water and groundwater were highly polluted by PTEs, with HPI values of 14,733 and 933, respectively. While PTEs pollution levels and risk in sediment and soil were low based on I-geo, CF, PLI, and M-ERM-Q values, PTEs contamination in river water may cause adverse impacts on aquatic living organisms (HQ > 1). The population doing recreational activities in river ecosystems was still safe from non-carcinogenic and carcinogenic impacts due to PTEs exposure from river water and sediment (THI < 1 and TCR value < 1E-04), while the population in the upper Citarum River was not safe from the carcinogenic risk due to PTE exposure from groundwater and soil (TCR > 1E-04). The sensitivity analysis showed that Cd concentration in groundwater is the most influential factor in cancer risk, with a total contribution of 99.9%. Therefore, a reduction in Cd concentration in groundwater is important to reduce cancer risk in the population.

Assessment of heavy metal distribution and bioaccumulation in soil and plants near coal mining areas: implications for environmental pollution and health risks

Monitoring heavy metals (HMs) across source distance and depth distribution near coal mining sites is essential for preventing environmental pollution and health risks. This study investigated the distribution of selected HMs, cadmium (Cd2+), chromium (Cr2+), copper (Cu2+), manganese (Mn2+), nickel (Ni2+), lead (Pb2+), and zinc (Zn2+), in soil samples collected from ten sites (S-1-S-10) at two different depths (0-15 and 15-30 cm) and distances of 50, 100, and 200 m from a mining source. Additionally, three plant species, Prosopis spp., Justicia spp., and wheat, were collected to assess HM bioavailability and leaf accumulation. Coal mine activities' impact on soil properties and their HM associations were also explored. Results reveal HM concentrations except for Cr2+ exceeding World Health Organization (WHO) limits. In surface soil, Cd2+ (58%), Cu2+ (93%), Mn2+ (68%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (88%) surpassed permissible limits. Subsurface soil also exhibited elevated Cd2+ (53%), Cu2+ (83%), Mn2+ (60%), Ni2+ (80%), Pb2+ (35%), and Zn2+ (77%). Plant species displayed varying HM levels, exceeding permissible limits, with average concentrations of 1.4, 1.34, 1.42, 4.1, 2.74, 2.0, and 1.98 mg kg-1 for Cd2+, Pb2+, Cr2+, Cu2+, Mn2+, Ni2+, and Zn2+, respectively. Bioaccumulation factors were highest in wheat, Prosopis spp., and Justicia spp. Source distance and depth distribution significantly influenced soil pH, electrical conductivity (EC), and soil organic carbon (SOC). Soil pH and EC increased with an increase in soil depth, while SOC decreased. Pearson correlation analysis revealed varying relationships between soil properties and HMs, showing a considerably negative correlation. Concentrations of HMs decreased with increasing depth and distance from mining activities, validated by regression analysis. Findings suggest crops from these soils may pose health risks for consumption.

Assessment of soil heavy metal pollution and associated ecological risk of agriculture dominated mid-channel bars in a subtropical river basin

The elevated concentrations of heavy metals in soil considerably threaten ecological and human health. To this end, the present study assesses metals pollution and its threat to ecology from the mid-channel bar's (char) agricultural soil in the Damodar River basin, India. For this, the contamination factor (CF), enrichment factor (EF), geoaccumulation index (I_geo), pollution index, and ecological risk index (RI) were measured on 60 soil samples at 30 stations (2 from each station, i.e., surface and sub-surface) in different parts of the mid-channel bar. The CF and EF indicate that both levels of char soil have low contamination and hence portray a higher potential for future enrichment by heavy metals. Moreover, I_geo portrays that soil samples are uncontaminated to moderately contaminated. Further, pollution indices indicate that all the samples (both levels) are unpolluted with a mean of 0.062 for surface soils and 0.048 for sub-surface soils. Both levels of the char have a low potentiality for ecological risk with an average RI of 0.20 for the surface soils and 0.19 for the sub-surface soils. Moreover, Technique for order preference by similarity to ideal solution (TOPSIS) indicates that the sub-surface soils have lower pollution than the surface soils. The geostatistical modeling reveals that the simple kriging technique was estimated as the most appropriate interpolation model. The present investigation exhibits that reduced heavy metal pollution is due to the sandy nature of soils and frequent flooding. However, the limited pollution is revealed due to the intensive agricultural practices on riverine chars. Therefore, this would be helpful to regional planners, agricultural engineers, and stakeholders in a basin area.

Hydrogeochemical characterisation and geospatial analysis of groundwater for drinking water quality in Ludhiana district of Punjab, India

This study characterises the quality of groundwater for the Ludhiana district of Punjab, India by analysing water samples collected from 152 locations spread across 3767 km². The samples were analysed for 18 parameters consisting of pH, EC, TDS, TA, TH, major anions and cations. The parameter values have been used to calculate the drinking water quality index of the study area which suggests that 2.6, 57.9, 32.9, 4 and 2.6% of the samples fall under the excellent, good, poor, very poor and unsuitable categories, respectively. The sequence of abundance for ions (in meq/l) as revealed from the laboratory tests is Na⁺ (37.1%) > Ca²⁺ (30.8%) > Mg²⁺ (29.1%) > K⁺ (2.8%) for cations and HCO₃^- (80%) > Cl^¯ (8.9%) > CO₃^2- (6.5%) > SO₄^2- (3.9%) > NO₃^-, F^-, PO₄^3- (< 1%) for anions. The spatial variability of these parameters has been depicted through the use of interpolation maps. Evaluation of different ionic ratios indicates that carbonate weathering and silicate weathering are both significantly affecting the groundwater chemistry with a slight dominance of carbonate weathering. Also, the ion exchange process is taking place in the area as confirmed by CAI index values. In terms of saturation index, the groundwater is undersaturated with respect to halite, fluorite and sylvite, whereas it is supersaturated for calcite, dolomite and aragonite minerals. The principal components in PCA explained 75.4% of the total variance with 29.1 and 28.3% contributions from PC1 and PC2. Both of these components indicate towards the geogenic and anthropogenic influence on groundwater mineralization of the area. The analysis suggests that groundwater for the study area is suitable for drinking in most of the region expect in a few places. Such a study could be used to understand the current status of groundwater quality in the area, the results of which can be used to prevent further contamination and sustain the resource for the future.

The concentration of potentially toxic elements (PTEs) in drinking water from Shiraz, Iran: a health risk assessment of samples

The existence of potentially toxic elements (PTEs) in water bodies has posed a menace to human health. Thus, water resources should be protected from PTEs, and their effect on the exposed population should be investigated. In the present investigation, the concentrations of PTEs such as lead (Pb), mercury (Hg), manganese (Mn), and iron(Fe) in the drinking water of Shiraz, Iran, were determined for the first time. In addition, hazard quotient, hazard index, cancer risk, and sensitivity analysis were applied to estimate the noncarcinogenic and carcinogenic impacts of Pb, Hg, Mn, and Fe on exposed children and adults through ingestion. The mean concentrations (µg/L) of Pb, Hg, Mn, and Fe were 0.36, 0.32, 2.28, and 8.72, respectively, in winter and 0.50, 0.20, 0.55, and 10.36, respectively, in summer. The results displayed that Fe concentration was more than the other PTEs. PTE concentrations were lower than the standard values of the Environment Protection Agency and World Health Organization. Values of the degree of contamination and heavy metal pollution index for lead, mercury, manganese, and iron were significantly low (< 1) and excellent (< 50), respectively. Based on the Spearman rank correlation analysis, positive and negative relationships were observed in the present study. The observations of the health risk assessment demonstrated that mercury, lead, iron, and manganese had an acceptable level of noncarcinogenic harmful health risk in exposed children and adults (hazard quotients < 1 and hazard index < 1). The carcinogenic risk of lead was low (< E - 06), which can be neglected. Monte Carlo simulation showed that water intake rate and mercury concentration were the most critical parameters in the hazard index for children and adults. Lead concentration was also the most crucial factor in the cancer risk analysis. The results of the present study proved that the drinking water of Shiraz is safe and healthy and can be confidently consumed by people.

Dissolution of harmful trace elements from coal and the environmental risk to mine water utilization

Under the pressure of water shortages, coal mine water has been allocated as a national water resource in China. However, the existence of harmful trace elements (HTEs) in coal mine water causes environmental risks and health concerns over its reuse. Through a lixiviation experiment, the dominant factors affecting the dissolution of HTEs in coal were simulated and analyzed, and the environmental risks of HTEs in coal mine water in China were evaluated for the first time. The average dissolved content levels of HTEs from coal were Mn > Cu > Zn > Ni > Ba > Cr > Co > V > Mo > Se > U > Pb > Cd, and the average maximum dissolution rates were Ni > Co > Mo > Zn > Cu > Cd > Mn > Se > Ba > Cr > U > Pb > V. Oxidation-reduction potential (Eh) and pH are the dominant factors controlling HTE dissolution. Higher oxygen exposure levels induce Eh and pH development, resulting in more HTE dissolution. This study constructed the dissolution potential index (F_C) of HTEs from coal. Based on the results of the F_C model, the areas with the highest migration potential and environmental risk of HTEs from coal seams to mine water are located in southern China, especially in the southwest, followed by areas of eastern Inner Mongolia and Shanxi and Shaanxi provinces. The corresponding risks in other regions are relatively low; thus, mine water utilization remains an effective option. This study provides an effective reference for the analysis of HTE enrichment in coal mine water and an evaluation of its safe utilization.

Distance impacts toxic metals pollution in mining affected river sediments

The study of metals mobility derived from mining activities in an ultramafic lithology is limited. This study investigates the effects of distance on potentially toxic metals such as Co, Cu, Fe, Mn, Ni, Pb, and Zn pollution, and the geochemical processes of fluvial system downstream of an ex-copper mine (Mamut River). The toxicity level of the river was evaluated using various sediment quality guidelines, ecotoxicological risks (ecological risk and risk index) and pollution indices. The geochemical behavior and stability of these toxic metals in the solid-phase samples were also examined. The results show that elevated concentrations of Ni, Cu, and Fe in the sediments can be linked to the adsorption and precipitation of metals from the aqueous-phase samples. We found that the metal scavenging rate as a function of distance is more evident in tropical environments than it was previously thought (10 km downstream). Such an inference could be explained by the greater amount of rainfall (pH 5.5-6.5) received in the tropics and higher weathering products that could react and form stable complexes. Geochemical analysis of the river sediment indicates that Ni, Cu, and Fe in the river sediment have increased 44-, 81-, and 90-fold compared to the background values, respectively. A significant decrease in the concentration of the potentially toxic metals was found at 5.5 km downstream. The scavenging rate of Fe is the highest (1485.82 μg g^-1 km^-1) followed by Cu (141.48 μg g^-1 km^-1), Ni (10.23 μg g^-1 km^-1), Pb (8.12 μg g^-1 km^-1) and Zn (5.01 μg g^-1 km^-1) in the tropical river system. In contrast, the concentration of Co and Mn in the river sediments doubled as the river flows approximately 5 km downstream due to the higher mineral solubility and weaker metal partition coefficient. This study also discusses the possibility of asbestos (mainly as chrysotile in the X-ray diffraction) as a potential hidden risk present within the ultramafic setting. This case study can be extrapolated to explain the dispersion of inorganic pollutants in an ultramafic environment in a global context.

Contamination and source-specific risk analysis of soil heavy metals in a typical coal industrial city, central China

Source-specific risk apportionment for soil heavy metals (HMs) is crucial for pollution mitigation and risk control in coal-mining areas. The ecological and human health risks resulting from different sources were evaluated through an integrated method that combines risk assessments with positive matrix factorization (PMF) model. Thirty soil samples were collected from a typical coal-mining city in central China and analyzed for six HMs (Cu, Ni, Pb, Cd, As, and Hg). The results indicate that surface soil in the study area suffered from moderate HMs pollution, especially pollution by Cd and Hg. Four potential sources of soil HMs were identified and quantified in the study area, including natural source (27.7%), traffic emissions (33.4%), agricultural practices (16.2%), and industrial activities (22.7%). The ecological risk of the study area was at moderate level, and the leading contributions in urban and suburban areas were from industrial activities and agricultural practices, respectively. The non-carcinogenic risks for adults and children were lower than the risk threshold, while the carcinogenic risks ranged between 1E-06 and 1E-04, suggesting that carcinogenic risks and hazards to human health should not be neglected. Traffic emissions and natural sources mainly contributed to the non-carcinogenic and carcinogenic risks, due to the strong non-carcinogenicity and carcinogenicity of As and Ni. These findings highlight the ecological and health risks linked to potential sources of soil HMs contamination and provide valuable information on the reduction of corresponding risks for local environmental managers.

Trace Elements in Sediments of Rivers Affected by Brown Coal Mining: A Potential Environmental Hazard

Brown coal remains an important energy source in Europe, including countries such as Germany, Poland, the Czech Republic, and Greece. Open-pit mines disturb the environment in terms of air quality, hydrology, and chemical and biological transformations in rivers receiving mine waters. In the present study, we assessed the impact of mine waters from four brown coal open-pit mines on the contamination of river sediments. Chemical analysis included the quantification of 62 elements, including heavy metals (HMs) and rare earth elements (REEs). The contamination of sediments by HMs was evaluated using the contamination factor (CF), the pollution load index (PLI), and the Nemerow multi-factor index (PI). The potential toxic effects of HMs on aquatic organisms were assessed using the potential ecological risk index (PERI). Detailed analysis of chondrite-standardized concentrations of REEs was performed to describe the effects of mine water on their pattern in sediments. Cluster analysis (CA) and principal component analysis (PCA) were employed to divide study sites into groups and to evaluate the combined effect of sediment texture and site location on HMs and REEs in sediments. The study showed that after mine water discharge, there is a decrease in HM and REE concentrations in sediments. The decrease in each element’s concentration in sites located 100 m downstream of the discharge was caused by washing out of the finest fractions of sediments by mine waters.

A first calibration of culturable bacterial diversity and their dual resistance to heavy metals and antibiotics along altitudinal zonation of the Teesta River

Culturable bacterial diversity and co-occurrence of heavy metal and antibiotic resistance were investigated from the water and sediments along the course of the Teesta River, in the Eastern Himalayas. Water and sediment samples collected from six sampling points during the monsoon and winter seasons were subjected to analysis of physico-chemical parameters, heavy metal contamination and antibiotic tolerance. The culturable bacterial diversity established by application of bacterial culture and 16S rRNA gene sequencing, ascertained the majority belonged to Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Deinococcus-Thermus. Among the 5 phyla, Proteobacteria and Actinobacteria were the dominant phyla present in both water and sediment samples, whereas Bacteroidetes, Firmicutes and Deinococcus-Thermus were unique to particular sites. The Shannon index indicated that the bacterial richness was more in the water column as compared to sediment. From the total of 245 isolates, 69 genera were identified. Heavy metal tolerance and antibiotic resistance profiles showed some isolates to be tolerant to high levels of heavy metals and multiple antibiotics indicating a major concern in terms of river ecosystem serving as a pool for dissemination of such resistant genes. The antibiotic resistance and heavy metal contamination diversified along the human-impacted downstream sites, endorsing the contribution of anthropogenic factors. The present report on bacterial diversity and the associated metal and antibiotics tolerance among bacteria is the first of its kind on Teesta River, the only major river system flowing through the state of Sikkim and parts of North Bengal.

Assessment of potability of minewater pumped out from Jharia Coalfield, India: an integrated approach using integrated water quality index, heavy metal pollution index, and multivariate statistics

The dense and industrialized populace in the mining areas of Jharia Coalfield (JCF) is plagued by a severe shortage of water supply. The unutilized pumped out coal minewater discharges may be utilized to cater to the increasing water demand of the region but it runs the risk of getting contaminated from domestic and industrial effluents. The current study aimed to assess the suitability of augmenting underground minewater for potable purposes. For this purpose, ninety underground minewater samples collected from 15 locations across JCF for the hydrological year 2019-2020 were analysed to gain an insight on the physicochemical characteristics of the minewater using an integrated approach of standard hydrochemical methods, integrated water quality index (IWQI), heavy metal pollution index (HPI), and multivariate statistical analysis. For the minewater quality to be deemed suitable for potable purposes, both IWQI (lower than 2) and HPI (lower than 30) values were considered. IWQI values of the minewater samples from the study area ranged from 1.97 to 5.08, while the HPI values ranged from 18.40 to 53.05. The pH of the samples were found to be mildly acidic to alkaline (6.5 to 8.3) with varying total hardness (149 to 719 mg L^-1), total dissolved solids (341 to 953 mg L^-1), and electrical conductivity (568 to 1389 µS cm^-1), reflecting heterogeneity in underlying hydrosystems, variations in geological formations, and the influence of lithogenic and anthropogenic processes on the water chemistry of the region, which was corroborated by the principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the minewater samples. Two major water types of the region were identified, viz., Ca-Mg-HCO₃ and Ca-Mg-Cl-SO₄. This multiparametric approach gives a holistically accurate assessment of the minewater quality, overcoming the limitations of traditional water quality indices and facilitating time-saving and effective water management practices, and sets the foundation for augmenting minewater for potable purposes to meet increasing demands.

Environmental health survey for children residing near mining areas in South Gobi, Mongolia

Background

We evaluated the level and factors of heavy metal exposure to children residing in the Togttsetsii, Khanbogd, and Bayandalai soums of South Gobi province, Mongolia.

Methods

A total of 118 children aged 9–12 years were surveyed, and the level of heavy metal exposure in their bodies was investigated. Exposure was investigated by measuring concentrations of heavy metals such as cadmium, lead, and mercury in the blood; mercury concentration in the hair; and total arsenic in the urine.

Results

Blood cadmium concentration had geometric averages of 0.16 µg/L in the children from Bayandalai, 0.15 µg/L Tsogttsetsii, and 0.16 µg/L Khanbogd. Blood lead concentration showed a relatively higher geometric average of 7.42 µg/dL in the children from Bayandalai compared to 4.78 µg/dL and 5.15 µg/dL in those from Tsogttsetsii and Khanbogd, respectively. While blood mercury concentration was the highest in the children from Bayandalai, with a value of 0.38 µg/L, those from Tsogttsetsii and Khanbogd had similar concentrations of 0.29 µg/L and 0.29 µg/L, respectively. Hair mercury concentration was the highest in the children from Bayandalai, with a value of 78 µg/g, a particularly significant difference, with a concentration of 0.50 µg/g in those from Khanbogd. Urine arsenic concentration was the highest in the children from Khanbogd, with a value of 36.93 µg/L; it was 26.11 µg/L in those from Bayandalai and 23.89 µg/L in those from Tsogttsetsii.

Conclusions

The high blood lead concentration of children in Bayandalai was judged to be due to other factors in addition to mine exposure; the reason why blood and hair mercury concentration was higher in children from Bayandalai may have been due to exposure to many small-scale gold mines in the area. In the case of Khanbogd, it was estimated that the high arsenic level in urine was caused by the effect of mines.

Impact of heavy metals on water quality and indigenous Bacillus spp. prevalent in rat-hole coal mines

The present study reports pollution evaluation indices employed to assess the intensity of metal pollution in water systems affected by acid mine drainage from rat-hole coal mines prevalent in North-east India. The concentration of seven eco-toxic metals was evaluated from coal mine waters which showed concentration order of Iron (Fe) > Manganese (Mn) > Zinc (Zn) > Chromium (Cr) > Lead (Pb) > Copper (Cu) > Cadmium (Cd). The water samples were acidic with mean pH 2.67 and burdened with dissolved solids (924.8 mg/L). The heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) displayed high and medium range of pollution level in majority of the water samples. Statistical correlation suggested strong positive correlation between metals such as Cr with Mn (r = 0.780), Mn with Fe (r = 0.576), Cr with Fe (r = 0.680), Pb with Mn (r = 0.579) and Cr with Pb (r = 0.606), indicating Mn, Pb, Fe and Cr to be major metal contaminants; an unequivocal affirmation of degradation in water quality. The sampled waters had lower heavy metal concentration during monsoon and post-monsoon seasons. The commonly occurring bacterial species Bacillus pseudomycoides and Bacillus siamensis were chosen to understand their behavioral responses toward metal contamination. Findings demonstrated that Bacillus spp. from control environment had low tolerance to metals stress as evident from their MTC, MIC and growth curve studies. The survival of the native isolates across varying pH, salinity and temperature in the coal mine areas suggest these isolates as promising candidates for reclamation of rat-hole coal mining sites.

Water-energy sustainability synergies and health benefits as means to motivate potable reuse of coalbed methane-produced waters

Management of coalbed methane (CBM)-produced water is a crucial part of the water-energy nexus, especially as CBM is projected to play a key role as a bridge fuel in major economies. In this paper, we consider one management technique, i.e., desalination of CBM-produced water to generate potable water. We discuss a confluence of geographic, sociotechnical, regulatory, and other circumstances that could make this concept viable for select coal-bearing regions. Having said that, for maximizing benefits, it is prudent to take a synergistic view targeting multiple objectives (water access, health, environmental impacts, and ease of waste management). Thus, we make design recommendations and suggest a system-evaluation framework for making sustainable decisions related to produced-to-potable water systems. For instance, a key question is whether such systems should be centralized or decentralized-and this paper highlights crucial tradeoffs that are present in both the cases.

Heterogeneous biochars from agriculture residues and coal fly ash for the removal of heavy metals from coking wastewater

While we have started down the path towards a global transition to a green economy, as with most things we began with the "low-hanging fruit," such that increasingly difficult material and chemical conversions remain. Coking is one such example; it is unlikely that steel production will transition away from using coking coal anytime in the near future, such that coking wastewater remains a global environmental challenge. However, we can develop greener methods and materials to treat such waste. The present work demonstrates how wheat straw, an abundant agricultural residue, can be co-pyrolyzed and co-activated with coal fly ash to produce a high surface area biochar. Coal fly ash has previously been shown to promote devolatilization and deoxygenation of pyrolyzed biofuels. This work shows how coal fly ash increases microporosity as well as aromaticity of the surface functional groups, while decreasing carbonyl but preserving or only slightly decreasing ketones and carboxylic acids. CO2-activation of 5 and 10 wt% fly ash with wheat straw blends yields heterogeneous biochars with adsorption capacities upwards of 170 mgmetal gchar -1, with 5 wt% blends showing higher capacity and adsorption uptake rates than the 0 or 10 wt% blends. The adsorption of the four heavy metals ions (Ni2+, Co2+, Zn2+, and Mn2+) was chemical in nature, with cobalt preferentially adsorbing to the char surface. The overall adsorption rate is limited by an initial rapid uptake to fill available surface adsorption sites.

Using Pb Isotope to Quantify the Effect of Various Sources on Multi-Metal Polluted soil in Guiyu

Guiyu is known as one of the largest e-waste disposal and recycling sites in China, which suffers greatly from heavy metal pollution. By evaluating the concentrations and distribution of 21 metal elements with Principal Component Analyses (PCA), five principal components were identified, which accounted for 70.4% of the information of the initial data matrix, including one e-waste recycling source, two geological sources, one source of human activities and one ocean aerosol source. Among them, the source of human activities cannot be detailed only by PCA. By using Pb isotope, the unexplained source was judged as battery sludge. Combining 21 metallic and metalloid element datasets with Pb isotope concentrations is more accurate and effective to identify uncertain sources in soil.

Spatiotemporal variability of heavy metals and identification of potential source tracers in the surface water of the Lhasa River basin

The Lhasa River basin is the economic and population center of Tibet and has abundant resources. Due to its harsh weather condition, high elevation, and inconvenient accessibility, few studies have focused on heavy metal distributions in this region. In the present study, to investigate the dissolved trace metal pollution and its controlling factors, 57 water samples from the Lhasa River and its tributaries were collected during three water flow regimes in 2016. The data on the dissolved fraction revealed that the Lhasa River basin appeared to have no to low pollution levels. However, the Lhasa River water showed alkaline characteristics which may affect the presence of heavy metal elements in a dissolved fraction. The concentration of heavy metal elements in colloidal or particulate matter therefore needs attention. Multivariate analyses were performed to determine the significant relationship between the data and to identify controlling factors for dissolved heavy metals in the study area. The results suggested that Mn, Cd, Cu, and Zn originated from a natural geological background, whereas Pb originated from mining drainage and As was influenced by geothermal flows. The concentration of dissolved heavy metals in the Meldromarchu tributary was greatly affected by the mining drainage water, while that in the Tölungchu tributary was greatly influenced by the geothermal water sources. This paper provides the first comprehensive analysis of dissolved heavy metal pollution characteristics and the controlling factors of pollution during the three different water flow regimes of the Lhasa River basin.

Study of the Water Quality of a Tropical Reservoir

A study of the water quality of the Adolfo López Mateos Reservoir (ALMD) was developed through different indicators from a spatial and seasonal perspective. Variables related to the general characteristics of water quality, trophic level, and ecological risk were assessed through the National Sanitation Foundation–Brown Water Quality Index (WQINSF–BROWN), the Carlson Trophic State Index (TSICARLSON) and the Håkanson Ecological Risk Index (RIHÅKANSON). Using data from physical, chemical, and biological parameters obtained from four sampling points in the ALMD, the water quality was assessed in each model used. The results indicated that the reservoir presents a water quality classified as “medium” (WQINSF–BROWN = 70), where significant variations in the concentrations of some parameters are observed. The reservoir showed a general trophic state (TSIGENERAL-AVERAGE = 43.04) classified as “mesotrophic”. The ecological risk analysis achieved the best classification of the methodology, discarding contamination by heavy metals in surface waters. This type of applied methodology will help in decision-making tools in the dam, and can be applied in other dams in the region.

Heavy metal speciation, leaching and toxicity status of a tropical rain-fed river Damodar, India

Speciations of metals were assessed in a tropical rain-fed river, flowing through the highly economically important part of the India. The pattern of distribution of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) were evaluated in water and sediment along with mineralogical characterization, changes with different water quality parameters and their respective health hazard to the local population along the Damodar River basin during pre-monsoon and post-monsoon seasons. The outcome of the speciation analysis using MINTEQ indicated that free metal ions, carbonate, chloride and sulfate ions were predominantly in anionic inorganic fractions, while in cationic inorganic fractions metal loads were negligible. Metals loads were higher in sediment phase than in the aqueous phase. The estimated values of I_geo in river sediment during both the seasons showed that most of the metals were found in the I_geo class 0-1 which represents unpolluted to moderately polluted sediment status. The result of partition coefficient indicated the strong retention capability of Cr, Pb, Co and Mn, while Cd, Zn, Cu and Ni have resilient mobility capacity. The mineralogical analysis of sediment samples indicated that in Damodar River, quartz, kaolinite and calcite minerals were dominantly present. The hazard index values of Cd, Co and Cr were > 1 in river water, which suggested potential health risk for the children. A combination of pragmatic, computational and statistical relationship between ionic species and fractions of metals represented a strong persuasion for identifying the alikeness among the different sites of the river.