Spatiotemporal distribution of boron in the groundwater and human health risk assessment from the coastal region of Bangladesh

Using unsupervised machine learning models to drive groundwater chemistry and associated health risks in Indo-Bangla Sundarban region

Groundwater is an essential resource in the Sundarban regions of India and Bangladesh, but its quality is deteriorating due to anthropogenic impacts. However, the integrated factors affecting groundwater chemistry, source distribution, and health risk are poorly understood along the Indo-Bangla coastal border. The goal of this study is to assess groundwater chemistry, associated driving factors, source contributions, and potential non-carcinogenic health risks (PN-CHR) using unsupervised machine learning models such as a self-organizing map (SOM), positive matrix factorization (PMF), ion ratios, and Monte Carlo simulation. For the Sundarban part of Bangladesh, the SOM clustering approach yielded six clusters, while it yielded five for the Indian Sundarbans. The SOM results showed high correlations among Ca2+, Mg2+, and K+, indicating a common origin. In the Bangladesh Sundarbans, mixed water predominated in all clusters except for cluster 3, whereas in the Indian Sundarbans, Cl--Na+ and mixed water dominated in clusters 1 and 2, and both water types dominated the remaining clusters. Coupling of SOM, PMF, and ionic ratios identified rock weathering as a driving factor for groundwater chemistry. Clusters 1 and 3 were found to be influenced by mineral dissolution and geogenic inputs (overall contribution of 47.7%), while agricultural and industrial effluents dominated clusters 4 and 5 (contribution of 52.7%) in the Bangladesh Sundarbans. Industrial effluents and agricultural activities were associated with clusters 3, 4, and 5 (contributions of 29.5% and 25.4%, respectively) and geogenic sources (contributions of 23 and 22.1% in clusters 1 and 2) in Indian Sundarbans. The probabilistic health risk assessment showed that NO3- poses a higher PN-CHR risk to human health than F- and As, and that potential risk to children is more evident in the Bangladesh Sundarban area than in the Indian Sundarbans. Local authorities must take urgent action to control NO3- emissions in the Indo-Bangla Sundarbans region.

Integrated clustering analysis for delineating seawater intrusion and heavy metals in Arabian Gulf Coastal groundwater of Saudi Arabia

The intrusion of seawater (SWI) into coastal aquifers is a major concern worldwide, affecting the quantity and quality of groundwater resources. The region of Saudi Arabia that lies along the eastern coast has been affected by SWI, making it crucial to accurately identify and monitor the affected areas. This investigation aimed to map the degree of seawater intrusion in a complex aquifer system in the study area using an integrated clustering analysis approach. The study collected 41 groundwater samples from wells penetrating multi-layered aquifers, and the samples were analyzed for physicochemical properties and major ions. Clustering analysis methods, including Hierarchical Clustering Analysis (double-clustering) (HCA-DC), K-mean (KMC), and fuzzy k-mean clustering (FKM), were employed to evaluate the spatial distribution and association of the groundwater properties. The results revealed that the analyzed GW samples were divided into four clusters with varying degrees of SWI. Clusters A, B, C, and D contained GW samples with very low (fsea of 1.9%), high (fsea of 14.9%), intermediate (fsea of 7.9%), and low (fsea of 5.2%) degrees of SWI, respectively. FKM clustering exhibited superior performance with a silhouette score of 0.83. Additionally, the study found a direct correlation between the degree of SWI and increased concentrations of boron, strontium, and iron, demonstrating SWI's impact on heavy metal levels. Notably, the boron concentration in cluster B, which endured high SWI, exceeded WHO guidelines. The study demonstrates the value of clustering analysis for accurately monitoring SWI and associated heavy metals. The findings can guide policies to mitigate SWI impacts and benefit groundwater-dependent communities. Further research can help develop effective strategies to mitigate SWI effects on groundwater quality and availability.

Human exposures to multiple water sources in the southwestern coastal region of Bangladesh: water quality, pollution sources, and preliminary health risks appraisals

The coastal areas of Bangladesh have poor accessibility to fresh drinking water and the groundwater is not suitable for drinking, cooking, and other domestic uses due to high levels of salinity and potentially toxic elements. The current study focuses on understanding of the distribution of some physicochemical parameters (temperature, pH, EC, TDS, and salinity) and chemical elements (Fe, Mn, Zn, Ca, Mg, Na, K, Cu, Co, Pb, As, Cr, Cd, and Ni) with health perspective in drinking water from the southwestern coastal area of Bangladesh. The physicochemical properties of the water samples were examined with a multiparameter meter, while the elemental concentrations were analyzed using atomic absorption spectrometer. Water quality index (WQI) and irrigation indices were utilized to determine the drinking water quality and irrigation feasibility, respectively, whereas hazard quotients (HQs) and hazard index (HI) were used to assess the probable pathways and the associated potential risks to human health. The concentrations of some toxic elements in measured samples were relatively higher compared to drinking water guidelines, indicating that ground and surface water are not apt for drinking and/or domestic uses. The multivariate statistical approaches linked the source of the pollutants in the studied water body mostly to the geogenic origin including saline water intrusion. WQI values ranged from 18 to 430, reflecting excellent to unsuitable categories of water quality. The assessment of human health risks due to exposure to contaminated water demonstrated both carcinogenic and non-carcinogenic health risks in the exposed residents of the study area. Therefore, appropriate long-term coastal area management strategies should be adopted in the study region for environmental sustainability. The findings of this research will be supportive in understanding the actual situation of fresh drinking water in the area for policymakers, planners, and environmentalists to take effective necessary measures to ensure safe drinking water in the study area.

Boron Exposure Assessment of Desalinated Seawater on an Island in China

This study aimed to investigate the boron level in drinking water and daily boron intake of island residents, and to have a health risk assessment of the boron exposure. One-year water boron surveillance was made through the 18 selected sampling sites (5 finished water and 13 tap water) covered by 5 water treatment plants with different water sources. We recruited 220 healthy volunteers (half men and half women) from 89 families covering all age groups living in Shengshan to provide basic information and living habits. One-third of the families attended the daily food boron intake evaluation through the double meal method for three days. In each family, only one family member provided the food samples. Urine samples were collected from all subjects to get the urine boron level. Furthermore, we used the EPA model and TDI for health risk assessments. The boron level in finished water and tap water with different sources were 0.68-1.46 mg/L and 0.62-1.26 mg/L for desalinated water, 0.30-0.39 mg/L and 0.20-0.50 mg/L for reservoir water, and 0.32-0.43 mg/L and 0.20-0.79 mg/L for mixture water. The average level of water boron intake, diet boron intake, and total boron intake was 0.113 ± 0.127 mg/d, 1.562 ± 0.927 mg/d, 1.674 ± 0.939mg/d, respectively, for the select sampling subjects. There were no significant differences in total boron intake for different age groups (1.685 ± 1.216 mg/d vs. 1.669 ± 0.793 mg/d for <45 yrs vs. ≥45 yrs, p = 0.968) and gender groups (1.754 ± 1.009 mg/d vs. 1.633 ± 0.923 mg/d for male vs. female, p = 0.735). Urine boron concentrations were similar in the two age groups (1.938 mg/g creatinine vs. 1.762 mg/g creatinine for <45 yrs vs. ≥45 yrs, p = 0.635). There were significant differences in urinary boron between males and females (1.569 mg/g creatinine vs. 2.148 mg/g creatinine, p = 0.018). The largest hazard quotient (HQ) of drinking water was 0.31, and the total boron exposures in this population were 0.03 mg/kg bw per day. The study showed that there was no possible non-carcinogenic risk of water boron exposure and lower health risk of total boron exposure to humans in this region, but its toxicity should not be ignored. The subsequent studies should strengthen the analysis of the subgroup populations.

A review of boron removal from aqueous solution using carbon-based materials: An assessment of health risks

Carbon-based compounds have gained attention of researchers for use in boron removal due to their properties, which make them a viable and low cost adsorbent with a high availability, as well as environmental friendliness and high removal efficiency. The removal of boron utilizing carbon-based materials, including activated carbon (AC), graphene oxide (GO), and carbon nanotubes (CNTs), is extensively reviewed in this paper. The effects of the operating conditions, kinetics, isotherm models, and removal methods are also elaborated. The impact of the modification of the lifetime of carbon-based materials has also been explored. Compared to unmodified carbon-based materials, modified materials have a significantly higher boron adsorption capability. It has been observed that adding various elements to carbon-based materials improves their surface area, functional groups, and pore volume. Tartaric acid, one of these doped elements, has been employed to successfully improve the boron removal and adsorption capabilities of materials. An assessment of the health risk posed to humans by boron in treated water utilizing carbon-based materials was performed to better understand the performance of materials in real-world applications. Furthermore, the boron removal effectiveness of carbon-based materials was evaluated, as well as any shortcomings, future perspectives, and gaps in the literature.

Spatial distribution of manganese in groundwater and associated human health risk in the southern part of the Bengal Basin

The scarcity of arsenic and iron-free safe drinking water is an alarming issue in the southern part of the Bengal Basin. The objectives of the present study were to investigate the spatial distribution of manganese (Mn) concentration in the shallow and deep groundwater and its associated health risks for the children and adults of entire southern Bengal Basin. The Mn concentration in the groundwater varied from 0 to 5.4 mg/L with an average value of 0.47 mg/L that exceeded the WHO's and Bangladesh drinking water guideline values of 0.4 and 0.1 mg/L, respectively. Mn concentration in the shallow wells overrode the deep ones. About 23% of the shallow wells and 11% of deep wells exceeded the WHO's safety limit of Mn concentration for human health. The human health risk related to Mn contamination was estimated by computing the average daily dosage (ADD) and hazard quotient (HQ) values for children and adults. The average computed HQ values found 0.108 and 0.099 for children and adults, respectively. The HQ values delimitated that children are posing a higher risk compared to the adults for the shallow wells. Deep wells were found risk-free for both children and adults. The areal coverage of shallow wells with HQ values > 1 was minimal compared to the total study area and covered only a small portion of Patuakhali and Barguna districts. The rest of the site does not pose any health risk due to Mn contamination for children and adults.