Spatial analysis and human health risk assessment of elements in ground water of District Hyderabad, Pakistan using ArcGIS and multivariate statistical analysis

Disclosing the key role of Fe/As/Cu in community co-occurrence and microbial recruitment in metallurgical ruins

Mining activities have led to the persistent presence of substantial heavy metals at metallurgical sites. However, the impact of long-term and complex heavy metal pollution in metallurgical ruins on the structure and spatial shift of microbiome remains unclear. In this study, we focused on various types of metallurgical sites to uncover the occurrence of heavy metals in abandoned mines and the response patterns of microbial communities. The results indicate that mining activities have caused severe exceedances of multiple heavy metals, with AsBio, CuBio, and FeBio being the primary factors affecting community structure and function. Co-occurrence network analyses suggest that several genera, including Ellin6515, Cupriavidus, Acidobacteria genus RB41, Vicinamibacteraceae, Blastococcus, and Sphingomonas, may play significant roles in the synergistic metabolism of communities responding to Fe-Cu-As stress. Although random dispersal contributed to community migration, null models emphasized that variable selection predominates in the spatial turnover of community composition. Additionally, metagenomic prediction (PICRUSt2) identified key genes involved in stress and detoxification strategies of heavy metals. The composite heavy metal stress strengthened the relationship between network structure and the potential function of the community, along with critical ecosystem functions. Our findings demonstrated that microbial interactions were crucial for ecosystem management and the ecological consequences of heavy metal pollution remediation.

Modern-Day Green Strategies for the Removal of Chromium from Wastewater

Chromium is an essential element in various industrial processes, including stainless steel production, electroplating, metal finishing, leather tanning, photography, and textile manufacturing. However, it is also a well-documented contaminant of aquatic systems and agricultural land, posing significant economic and health challenges. The hexavalent form of chromium [Cr(VI)] is particularly toxic and carcinogenic, linked to severe health issues such as cancer, kidney disorders, liver failure, and environmental biomagnification. Due to the high risks associated with chromium contamination in potable water, researchers have focused on developing effective removal strategies. Among these strategies, biosorption has emerged as a promising, cost-effective, and energy-efficient method for eliminating toxic metals, especially chromium. This process utilizes agricultural waste, plants, algae, bacteria, fungi, and other biomass as adsorbents, demonstrating substantial potential for the remediation of heavy metals from contaminated environments at minimal cost. This review paper provides a comprehensive analysis of various strategies, materials, and mechanisms involved in the bioremediation of chromium, along with their commercial viability. It also highlights the advantages of biosorption over traditional chemical and physical methods, offering a thorough understanding of its applications and effectiveness.

Groundwater Contamination in Arid Coastal Areas: Qatar as a Case Study

The Arab region is located in an arid environment and suffers from water scarcity and poor water quality which are expected to become more severe in coming years due to global warming. In this study, the groundwater quality of 205 wells in Qatar was investigated. The physical parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, inorganic carbon (IC), and organic carbon (OC) were determined. The study characterized the concentrations of major anions of Cl, F, Br, NO3, PO4, and SO4, and major cations of Ca, K, Mg, and Na. Importantly, metals and metalloids including V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb, and U were determined. The results revealed that the groundwater of all wells is not drinkable due to high salinity (average TDS 4598 mg/L and salinity 0.4%, respectively). Additionally, average concentrations of major anions Cl, SO4, and F were 1472, 1064, and 1.9 mg/L, respectively, and all exceed the World Health Organization (WHO) guidelines for drinking water. However, NO3 concentration in 11 out of 205 wells was above the WHO guidelines of 50 mg/L due to intensive agriculture and fertilizer applications. Major cations of Ca, K, Mg, and Na were higher than WHO guidelines with average concentrations of 345, 63, 127, and 923 mg/L, respectively. All trace metals were much lower than the WHO guidelines for drinking water; however, the vanadium (V) average concentration in groundwater of all wells was 31 μg/L, which is five times higher than the Dutch guidelines (whereas the WHO has no guidelines for V). The groundwater of Qatar is dominated by Ca and Mg sulfates in Sabkha environments and dominated by NaCl in the coastal zones from evaporate environments consisting of coastal salt flats, salt pans, estuaries, and lagoons supersaturated by salts and the influence of sea water intrusion.

Source apportionment, source-specific health risks, and control factors of heavy metals in water bodies of a typical karst basin in southwestern China

Studying the apportionment of source-specific health risks and control factors for heavy metal pollution in karst regions is crucial for prevention and management. A typical karst basin was chosen in this study to investigate the pollution characteristics of heavy metals, source-specific health risks, and control factors. The results indicate that during the rainy season, As, Cd, and Pb, as well as As during the dry season, were the primary elements responsible for water pollution in the watershed. Comparative analyses showed that the absolute principal component-multiple linear regression (APCS-MLR) model better identifies and quantifies the sources of heavy metals in karst basin waters. The analysis of health risks revealed that during the dry season, heavy metals in the basin posed a moderate cancer risk to adults (10-4 < total cancer risk (TCR) < 10-3), whereas during the rainy season, these heavy metals posed a non-cancer risk (total hazard index (THI) > 1) and a moderate to high cancer risk (10-4 < TCR < 10-2). The APCS-MLR model combined with the health risk analysis showed that Industrial waste discharge sources are the main contributors to the health of basin residents (29.39%-52.57%), making dry season As a non-cancer risk for basin residents, as well as rainy season As and Cd a non-cancer risk and a high cancer risk for basin residents. Therefore, reasonable planning for upstream industrial production should be developed, and priority should be given to monitoring and treating As and Cd pollution in water. Analyses also showed that input pathways, dilution effects, and hydrochemical characteristics may influence the spatial and temporal variability of heavy metals in the basin. The results provide essential information and significant reference for prioritising and managing the health risks associated with heavy metal pollution in water bodies in karst areas.

Vertical Distribution Characteristics and Ecological Risk Assessment of Mercury and Arsenic in Ice, Water, and Sediment at a Cold-Arid Lake

Mercury and arsenic are two highly toxic pollutants, and many researchers have explored the effects of the two substances on the environment. However, the research content of toxic substances in frozen periods is relatively small. To explore the spatial and vertical distribution of mercury and arsenic in the ice, water, and sediments of Wuliangsuhai Lake under ice conditions, and to assess the harm degree of the two toxic substances to human beings. We collected the ice, water, and sediments of the lake in December 2020, and tested the contents of Hg and As. The single-factor pollution index method, the local cumulative index method, and the ecological risk coding method were used to assess the pollution status in these three environmental media, and the Monte Carlo simulation combined with the quantitative model recommended by USEPA was used to assess the population health risk. The results showed that (1) The average single-factor pollution values of Hg and As in water were 0.367 and 0.114, both pollutants were at clean levels during the frozen period. (2) The mean Igeo values of Hg and As were 0.657 and -0.948. The bioavailability of Hg in the sediments of Wuliangsuhai Lake during the frozen period was high, and its average value was 7.8%, which belonged to the low-risk grade. The bioavailability of As ranged from 0.2% to 3.7%, with an average value of 1.3%. (3) Monte Carlo simulation results indicate acceptable levels of health risks in both water and ice. This study preliminarily investigated the distribution characteristics of toxic substances and their potential effects on human health in lakes in cold and arid regions during the frozen period. It not only clarified the pollution characteristics of lakes in cold and arid regions during the frozen period, but also provided beneficial supplements for the ecological protection of lake basins. This study lays a foundation for further environmental science research in the region in the future.

Human health risks associated with the consumption of groundwater in the Gaza Strip

Groundwater of the Gaza Strip, the main source of drinking water for the Gazans, is highly contaminated by several chemicals of natural and anthropogenic origins. The results of this study confirm the findings of several studies conducted over the past two decades. Over those two decades, the population of Gaza has doubled, resulting in heavy demand for the limited reserves of groundwater. After 20 years since the first comprehensive study, it was found that groundwater salinity increased by 30 %, due to seawater intrusion. On the other hand, nitrate (NO3) decreased by 30 %, due to expansion of the sewer network and decrease in the number and distribution of septic tanks. Salinity, chloride (Cl), NO3 and fluoride (F) distribution maps for the year 2022 are very similar to those of the year 2002. This indicates that sources and loads of such contaminants are still the same. Metals and metalloids are still within the permissible limits set by the World Health Organization (WHO). Strontium (Sr) only showed concentrations of 12 mg/L across the Gaza Strip, which calls for further investigations. Maximum concentrations of the NO3 and F were 365 and 2.6 mg/L, respectively. The results of probabilistic risk assessment using Monte Carlo simulation showed that NO3 and F consumption through drinking water were above the reference dose for 35 % and 5 % of the trials performed, respectively. Consequently, the hazard quotient (HQ) is larger than 1 for 35 % and 5 % of the exposure scenarios simulated for these ions. For all metals and metalloids analyzed, HQ were below one (HQ1) indicating no risk; however, Sr presented an HQ 95th percentile equal to 0.19. Exposure routes such as dietary intake and soil ingestion, among others, should be further investigated to ensure that cumulative exposure does not surpass the safety limit. Recent advances in desalination technology should put an end to this truly regrettable situation.

Water quality monitoring in southern Brazil and the assessment of risk factors related to contamination by coliforms and Escherichia coli

The potability of water, including underground sources, is constantly affected by human activities. To assess water quality and water security in rural and urban areas of southern Brazil, a quantitative, retrospective analysis of water samples collected monthly by the Brazilian health authorities (19,687 samples from 2013 to 2021) was performed. In rural areas, 5,979 water samples (77.54%) were found to be contaminated by coliform bacteria and 3,431 (44.50%) by Escherichia coli. In addition, 1,616 (20.95%) of the contaminated samples were significantly correlated with rainfall amount. In urban areas, 1,268 (10.95%) of the samples contained coliform bacteria and 293 (2.53%) of these samples contained E. coli, with the factor of rainfall associated with 1,081 samples (9.33%) with bacterial contamination. In terms of physicochemical parameters, turbidity exceeded the national standard (5 uT) in 448 (2.32%) samples and fluoride fell below the required level (0.8 mg/L) in 106 samples (0.54%). The presence of free residual chlorine (0.2-2.0 mg/L) was verified in 846 samples (14.38%) in rural areas and in 10,825 samples (56.13%) in urban areas. These results suggest a strong association between rainfall factors and physicochemical alterations, as well as the risk of greater microbial contamination of water for human consumption.

Health risk assessment of heavy metals and disinfection by-products in drinking water in megacities in China: A study based on age groups and Monte Carlo simulations

Heavy metal(loid)s (HMs) and disinfection by-products (DBPs) in drinking water pose risks to human health and jeopardize drinking water. Water-related behaviors vary significantly among different age groups and regions. In this study, the carcinogenic and non-carcinogenic risks of HMs (As, Cd, Cr6+, Cu, Pb, and Zn) and DBPs (bromodichloromethane (BDCM), bromoform, chloroform, dibromochloromethane (DBCM), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA)) in drinking water in two Chinese megacities (Beijing in North China and Guangzhou in South China) via multiple exposure pathways were assessed. The results showed that children aged 9 months to 2 years had a total carcinogenic risk (TCR) and hazard index (HI) above acceptable levels, indicating that despite the drinking water quality in the selected megacities meeting the current Chinese national standards (GB 5749-2022), the health risks of exposure to HMs and DBPs in drinking water for local young children should not be neglected. Specifically, the carcinogenic risk (CR) of exposure to As in drinking water for children < 18-years-old, who were divided into different age groups, was 1.5-2.0- and 4.5-5.9-times higher than the TCR of exposure to DBPs in Beijing and Guangzhou, respectively. Regarding children aged 9 months to 2 years, the exposure to TCAA accounted for the largest proportion (35.6 %) of the TCR of exposure to DBPs in Beijing drinking water, 5.4-times higher than that in Guangzhou; whereas, the TCR of exposure to DBPs in Guangzhou drinking water was predominantly caused by exposure to chloroform, accounting for 40.6 % of the TCR and 1.5-times higher than that in Beijing. In addition, the CR of exposure to DCAA in drinking water in both megacities accounted for a large proportion of the TCR for children aged 9 months to 2 years. Monte Carlo simulations showed that 62.2 % and 42.6 % of the TCR of simultaneous exposure to As and DBPs in drinking water exceeded the acceptable level for sensitive populations, that is, children aged 1-2 years in Beijing (95th percentile = 4.2 × 10-4) and children aged 9-12 months in Guangzhou (95th percentile = 5.2 × 10-4), respectively. This elaborate health risk assessment sheds light on improving the water quality indices to guarantee drinking water safety in China.

Spatial distribution of arsenic and metals suggest a high ecotoxicological potential in Puno Bay, Lake Titicaca, Peru

Spatial distribution and interpolation methods provide a summarized overview about the pollution dispersion, concerning the environment's quality. A high-altitude lake was taken as a model to assess the metalloid As and metals Cr, Cu, Ni, Pb, Zn distribution in superficial sediment and classify them according to their ecotoxicological potential in the aquatic environment. Surface sediments were collected from 11 sites along Puno Bay located at the western area of Lake Titicaca, Peru, and analyzed for pseudo total-metals. Sediment concentration data and quality were plotted using the Inverse Distance Weighting (IDW) as an interpolation method. High concentrations of As were found especially in the outer bay (81.73 mg.kg^-1). Spatial heterogeneity was evidenced for metal by the coefficient of variation, although no significative differences were observed between the two bays applying a Kruskall Wallis test (p < 0.05, df = 1). Sediment quality classification showed that most metal values were below TEL and toxicity was unlikely to occur, only As exceeded threefold PEL values, which categorized sediment as "Very Bad", indicating a rather high ecotoxicological potential to the aquatic environment. In conclusion, spatial analysis connected to interpolation methods demonstrated the superficial sediment heterogeneity in Puno Bay.

Study on metal elements in indoor particulate matter: a case study of rural residential environment in Northeast China

The use of solid fuels for heating and cooking in rural Northeast China has led to severe indoor metal element pollution in particulate matter (PM), posing a direct threat to human health and creating immense pressure on the sustainability of residential environments. To investigate the levels, sources, and potential health hazards of indoor metal element pollution in this region, we conducted a year-long sampling and monitoring campaign in actual residential settings and used ICP-OES to measure six metal elements (Mn, Cr, Zn, Cu, Pb, and Ni). This study's findings reveal that indoor metal element pollution levels in PM (33,513.65 mg/kg per year) are higher in rural Northeast China compared to other rural areas. Straw burning is the primary source of metal element pollution, followed by motor vehicle emissions and natural soil sources. It is crucial to note that our results indicate a total carcinogenic risk greater than 10^-4 according to the US EPA health risk model assessment, highlighting the high risk posed to human health by indoor metal elements in rural areas. By using a seriously polluted area in Northeast China as a case study, this research provides initial insights into the characteristics and sources of indoor metal pollution in rural areas, offering a reference for future prevention and control of indoor pollution in these regions. Ultimately, this work can help improve the rural habitat and enhance the health of the rural population.

Heavy metal(loid)s contamination and potential risk assessment via groundwater consumption in the district of Hangu, Pakistan

This study examined the concentration of heavy metal(loid)s (HM) in groundwater and associated health risks in the Hangu District, Pakistan. Seventy-one groundwater samples were selected from various sources to determine the concentration of twelve HM using the ICP-MS. The average concentrations of HM in groundwater were observed within acceptable guidelines proposed by the World Health Organization (WHO). Similarly, the groundwater of the study area based on the HM contamination index results was noted as an excellent group. Generally, the chronic daily intake (CDI) values for both adults and children were observed in the sequence of Fe > Zn > Ni > Mn > Cu > Sb > Cr > Mo > As > Pb > Co > Cd. The highest hazard quotient was computed for children through groundwater from the tube well. Moreover, both carcinogenic and non-carcinogenic hazards of groundwater were observed in the order of tube well > dug well > spring > bore well. The present study suggests that children were more susceptible to health risks than adults.

Drinking water quality monitoring, assessment and management in Pakistan: A review

In this review, the importance of a robust frame work for drinking water quality monitoring, assessment and management has been discussed. This review presents the global overview of the drinking water quality, illuminating the global challenges of water supply system from catchment to consumers and briefly discussing appropriate regulatory frameworks and risk analysis tools. It also presents meticulous summaries of water reports released by the government and non-governmental organizations with special emphasis on health-based targets, proposed strategies related to preventive risk management (through water safety planning), environmental impact assessment (EIA), and independent surveillance in Pakistan. This paper reviews various studies published in national and international journals and reports, released by the government and non-governmental organizations, to provide a summary of the current knowledge with regards to the contemporary water quality management system that is still developing in the country. Role of agencies and their policies for water quality management and monitoring is one of the most important impact categories that has been covered in this review. The reviewed publications provide strong support for claims that impacts of unsafe water on health and economy of a country are very dangerous. Improved access to safe drinking water by a development-oriented strategy can have tangible improvements in socioeconomic status of a country.

Assessment of water quality, trace metal pollution, source apportionment and health risks in the groundwater of Chakwal, Pakistan

Groundwater quality evaluation is the main concern in the regions like Chakwal where it is major source of water for drinking and irrigation due to low storage capacity of the surface water and lack of proper irrigation system. The aim of the present study was to evaluate various physicochemical parameters (pH, EC, TDS, DO, TA, TH and chlorides) and selected essential/toxic trace metal concentrations (Na, K, Ca, Mg, Sr, Li, Ag, Zn, Fe, Cu, Co, Mn, Cr, Cd, and Pb) in order to explore their distribution, correlation, spatial variations and health risk assessment. Average concentration of some trace metals (Co, Cd and Pb) and physicochemical parameters (EC, TDS, and alkalinity) were found to exceed the national/international standards. Multivariate methods of analysis showed strong associations among Fe-Li-K, Sr-Mg-Ca, Cd-Mn, Cu-Zn, Ag-Co, and Cr-Pb-Na which were significantly contributed by anthropogenic activities. Irrigation water quality index exhibited intermediate suitability of the groundwater for irrigation purpose. Health risk evaluation of the trace metals revealed significant non-carcinogenic risks for Cd, Co and Pb (HQ_ing > 1) especially for children. Similarly, significant carcinogenic risk was found to be associated with Pb and Cr which exceeded the safe limit, suggesting the lifetime carcinogenic risk associated with these metals in the groundwater. The present health risk problems should be considered on top priority and immediate actions should be taken to safeguard the water quality in the study area.

Engineering microbes for enhancing the degradation of environmental pollutants: A detailed review on synthetic biology

Anthropogenic activities resulted in the deposition of huge quantities of contaminants such as heavy metals, dyes, hydrocarbons, etc into an ecosystem. The serious ill effects caused by these pollutants to all living organisms forced in advancement of technology for degrading or removing these pollutants. This degrading activity is mostly depending on microorganisms owing to their ability to survive in harsh adverse conditions. Though native strains possess the capability to degrade these pollutants the development of genetic engineering and molecular biology resulted in engineering approaches that enhanced the efficiency of microbes in degrading pollutants at faster rate. Many bioinformatics tools have been developed for altering/modifying genetic content in microbes to increase their degrading potency. This review provides a detailed note on engineered microbes - their significant importance in degrading environmental contaminants and the approaches utilized for modifying microbes. The genes responsible for degrading the pollutants have been identified and modified fir increasing the potential for quick degradation. The methods for increasing the tolerance in engineered microbes have also been discussed. Thus engineered microbes prove to be effective alternate compared to native strains for degrading pollutants.