Distribution and Risk Assessment of Heavy Metals in Surface Water from Pristine Environments and Major Mining Areas in Ghana

Hazard-mapping and health risk analysis of iron and arsenic contamination in the groundwater of Sylhet district

This study investigates groundwater contamination by arsenic and iron and its health implications within the Sylhet district in Bangladesh. Utilizing geographic information system (GIS) and inverse distance weighting (IDW) methods, hazard maps have been developed to evaluate contamination risk across various upazilas. The findings show significant arsenic and iron pollution, particularly in the northwestern part of the district. In about 50% of the area, especially in Jaintiapur, Zakiganj, Companiganj, and Kanaighat where arsenic levels surpass 0.05 mg/L which is the standard limit of Bangladesh. Iron levels peak at 13.83 mg/L, severely impacting 45% of the region, especially in Gowainghat, northeastern Jaintiapur, Zakigonj, and Golabganj. The study employs USEPA health risk assessment methods to calculate the hazard quotient (HQ) and hazard index (HI) for both elements via oral and dermal exposure. Results indicate that children face greater noncarcinogenic and carcinogenic risks than adults, with oral HI showing significant risk in Balagonj and Bishwanath. Dermal adsorption pathways exhibit comparatively lower risks. Cancer risk assessments demonstrate high carcinogenic risks from oral arsenic intake in all areas. This comprehensive analysis highlights the urgent need for effective groundwater management and policy interventions in the Sylhet district to mitigate these health risks and ensure safe drinking water.

Ecological and human health risk assessment of potentially toxic elements in water and soils within a crude oil waste management facility, Southwestern Ghana

Crude oil waste management is challenging due to the diverse constituents of the waste and its consequent impact on valued environmental receptors (water and soil). Characterization of the potentially toxic elements (PTEs) in soils and water within the surroundings of crude oil waste management facility is imperative, to aid evaluation of potential risks. The study assessed the potential environmental and human health risks posed by PTEs in soil and water from surroundings and adjoining settlement communities. A total of forty-four (44) samples were analyzed for PTEs (Cr, Pb, Zn, Co, Mn, Ni, Hg, Fe, As, Cu, Hg, and Cd) and physicochemical properties in both matrices. The total carcinogenic risk (TCR) for adults and children in the neighbouring community was 4.73 × 10-6 and 1.2 × 10-4, respectively, which was due to the high carcinogenic slope factor of arsenic. A strong correlation was observed between the PTEs and physicochemical properties, and their health risk was attributed to both geogenic and anthropogenic factors. The study indicated that the human health and ecological risk values obtained were within acceptable limits, with the waste management facility posing a higher risk in comparison to the nearby community. These risks may be attributed to the specific nature and intensity of the activities conducted at the facility. Hence, there is the need for continuous promotion of occupational and public awareness on the health and environmental impact of crude oil waste management.

Contamination, ecological, and human health risks of heavy metals in water from a Pb-Zn-F mining area, North Eastern Nigeria

In Nigeria, artisanal mining has become a serious issue. In the Nigerian mining region of Arufu Pb-Zn-F, this study assessed the level of pollution, ecological hazards, and health risks related to the presence of metals in the water. In the dry and rainy seasons, 36 water samples (20 from the ground, 10 from the surface, and six from the mine) were gathered. Samples were examined for the presence of heavy metals such as Cr, Co, Ni, Cu, Zn, As, Cd, and Pb. Other than Cu, Zn, As, Cd, Sb, and Cd (surface water, dry season), which were below the acceptable norm, all water samples had metals over the suggested limits. Heavy metals from nearby mining activities polluted the water, according to contamination evaluations utilizing the contamination factor (CF). Metals in the water may pose very significant ecological dangers, according to ecological risk assessments. The evaluation of human health risks revealed that both adults and children in the region are susceptible to carcinogenic and non-carcinogenic health hazards since the hazard index (HI) values for both indices were above 1 × 10-5 and above 1, respectively. This report emphasizes the need for monitoring mining operations in the nation to safeguard public health.

Determination of Heavy Metal Pollution in the Dankran River in the Bekwai Municipality of Ghana

Water pollution has been a major issue across the globe because of industrial activities to meet the needs of people. Many chemicals are released into the environment through these processes, which affect human health and the environment. Hence, the study aimed to assess the concentration of heavy metals (Cu, Zn, Mn, Ni, Hg, and Fe) and the physicochemical and biological properties of the Dankra River. The samples were taken from three locations, Konyaw, Jumako, and Anwiankwanta, and subjected to standard laboratory tests using Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Results revealed that the Dankran river was not polluted with the selected heavy metals under study. The physicochemical properties, the biological oxygen demand (BOD), chemical oxygen demand (COD), and nitrogen, phosphorus, and potassium (NPK) concentrations were all within the allowable healthy limits according to WHO standards. Iron was the predominant metal in the Dankran river, with the highest concentration of 6.5913 mg/l. Thus, the river is safe to use, but there is a need for regular monitoring to support life. The order of concentration of the investigated metals follows this pattern in descending order: Fe > Mn > Cu > Zn > Ni > Hg.

Probabilistic risk assessment and water quality index of a tropical delta river

Water plays a major role in supporting the wellness and life processes in living things as well as in the ecological structure's stabilities. However, several environmental scientists have recounted the alarming menace unfit water quality portends as well as the shortfalls of its global utilization in various spheres of life. This study aims to determine the fitness of the Ossiomo River and its likely health risk impact when consumed or used for other domestic purposes. The outcome of the physicochemical and heavy metal characterization showed that most of the parameters surpassed the slated benchmarks. Findings from the study revealed a significant difference (p < 0.05) for water temperature, color, TDS, BOD₅, HCO₃, Na, Fe, Mn, and THC across the four stations respectively. Meanwhile, pH, salinity, turbidity, TSS, DO, Cl, P, NH₄H, NO₂, NO₃, SO₄, Zn, Cu, Cr, Ni, Pb, and V showed no significant (p > 0.05) across the four stations respectively. The pH level of the water was slightly acidic at the range of 4.40-6.82. The outcome of the computed water quality index showed that station 1 (66.38) was poor for human ingestion which was above the set slated benchmarks of 26-50. However, stations 2-4 (163.79, 161.79, and 129.95) were unsuitable for drinking which was above the set slated benchmarks of 100. The outcome of the health risk evaluation revealed that the hazard quotients (HQs) were considered greater than 1 (>1) for Cr (2.55). The hazard index (0.46) via the dermal pathway was <1 while the ingestion (4.35) pathway was >1. The sum of the HQs (4.81) was also > 1. Thus, there are possible non-carcinogenic health risks via direct ingestion of the water. The outcome from the carcinogenic risk for Pb, Cr, and Cd (6 × 10^-3, 4.00 × 10^-1, and 1.22 × 10⁰), was somewhat greater than the target goal (1.0 × 10^-6 to 1.0 × 10^-4) of carcinogenic risks stipulated by the United States Environmental Protection Agency for drinking water, respectively, especially for Cd. There might be a potential carcinogenic risk if the water is consumed when the metal contents are higher than the target limits set. Sustainable farming and treatment of wastes from industrial outputs should be the main management of this watercourse.

Vertical distribution of the toxic metal(loid)s chemical fraction and microbial community in waste heap at a nonferrous metal mining site

Over the past few decades, nonferrous mining has produced numerous waste rock and part of the waste that has not been properly treated was generally dumped at roadsides and hill slopes. However, the vertical distributions of toxic metal(loid)s and composition of microbial communities in waste heap and the under-laid pristine soil are rarely studied. In this work, the fraction-related distributions of toxic metal(loid)s were investigated at a waste heap profile and the indigenous microbial assemblages were also analyzed by Illumina sequencing of 16 s rRNA genes. Results showed that compared to the under-laid pristine soil, content of toxic metal(loid)s, especially Cd, As and Pb, in waste rock layer were higher. Most of As in subsoil existed as non-specifically sorbed and specifically-sorbed fractions, which could be ascribed to the migration from the upper layer. The mobility was significantly correlated with Eh, EC, clay content, CEC and the total content of metal(loid)s. Phyla Proteobacteria, Acidobacteria and Firmicutes dominated the microbial communities. The microbial community compositions at the genus level were similar, but their relative abundances were mainly influenced by pH, CEC, Eh, SOM, and bioavailability content of toxic metal(loid)s. Besides, microbial functions of elements (S, Fe, Mn and As) oxidation/reduction and metabolites (siderophore, biosurfactant, organic acid, phosphatase and urease) potentially were used for pollutants bioremediation.

The AKOBEN programme as a tool towards responsible gold mining in Ghana, business as usual or a commitment towards sustainable development

The AKOBEN Programme, an environmental performance rating and disclosure initiative that show the environmental performance of gold mining firms with reference to their daily activities post environmental impact assessment and issuance of an environmental permit was introduced in Ghana to serve as a monitoring and verification tool towards environmental compliance and responsible mining. As to whether the AKOBEN Programme is enhancing the environment and or safeguarding public health in Ghana needs to be investigated. A systematic multi-methods environmental audit approach comprising of comparative analysis, time series analysis, air and water quality indices were used within the framework of the Driver-Pressure-State-Impact-Response to answer the questions what is happening to the environment and what the consequences for the environment and humanity are. The quality and suitability of River Kwabrafo as a habitat for aquatic life, for agricultural, recreational and drinking purposes pre and post AKOBEN Programme introduction as well as the quality of agricultural soils and river sediments in gold mining communities was determined. The study revealed that the AKOBEN Programme rates gold mining firms based on variable-by-variable concentrations of toxic water pollutants such as As, Cd, Hg, CN and non-toxic water pollutants such as pH, suspended solids, dissolved solids and electrical conductivity without taking into account the cumulative effect of the pollutants and the various uses of water. Results on the quality of River Kwabrafo based on the Canadian Council of Ministers of the Environment Water Quality Index confirmed no differences in water quality concerning use for agriculture, recreation, drinking and as a habitat for aquatic life before and after the introduction of the AKOBEN Programme. The study also revealed the quality of air at Anyinam to be acceptable with reference to PM10 and unhealthy with reference to total suspended particulate (TSP). The AKOBEN Programme failed to delineate TSP into oxides of nitrogen, carbon dioxide, methyl mercury and oxides of sulphur for which reason the impacts of greenhouse gases and methyl mercury on the Obuasi Municipality could not be investigated under the AKOBEN Programme. Mean arsenic concentrations for all study sites exceeded the arsenic reference for Ghana with significant differences existing between mean soil Cd and Hg levels at AKOBEN sites, Non-AKOBEN sites and Control sites. This study will not only elucidate the environmental and health problems associated with gold mining operations at AKOBEN and Non-AKOBEN sites in Ghana, but will also present complex water quality data into simple communication format for easy understanding to policy makers and non-expert audience.

Concentrations and Human Health Risk of Heavy Metals in Rivers in Southwest Nigeria

BACKGROUND

Rivers are the most vital freshwater resources in the world. In Southwest Nigeria, anthropogenic activity stresses the quantity and quality of water resources.

METHODS

The present study examined the concentrations and human health risk of five heavy metals (manganese (Mn), arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb)) in selected rivers in Southwest Nigeria. The determination of heavy metals was carried out by atomic absorption spectrophotometry after digestion with a di-acid mixture 9:4 (v/v) (nitric acid: perchloric acid).

RESULTS

All rivers had higher concentrations of the five heavy metals in the dry season except for As in Dandaru (0.012 mg/L) and Asejire (0.016 mg/L). Manganese was observed to have the highest mean concentration among all the five metals in both the rainy and dry seasons across the sampled rivers. Generally, the annual mean concentration of metals followed the order: Mn>Cr>Cd>Pb>As in all the selected rivers.

DISCUSSION

The human health risk assessment showed that the hazard index and hazard quotient for ingestion of water for Cd and As in all the sampled rivers were higher than the acceptable limit of 1.0, indicating carcinogenic risk (CR) via direct ingestion of water. The CR via ingestion for As in all of the sampled rivers was above the remedial goal target of 1×10-6. The recorded values for chronic daily intake (CDI) were higher for Cr and Mn in all four sampled rivers.

CONCLUSIONS

The results of the present study showed that As is a driver for carcinogenic risk through ingestion in all of the sampled rivers compared to other metals.

COMPETING INTERESTS

The authors declare no competing financial interests.