Identification of heavy metals source within selected active dumpsites in southeastern Nigeria

Environmental effects from petroleum product transportation spillage in Nigeria: a critical review

Nigeria has struggled to meet sustainable development goals (SDGs) on environmental sustainability, transportation, and petroleum product distribution for decades, endangering human and ecological health. Petroleum product spills contaminate soil, water, and air, harming humans, aquatic life, and biodiversity. The oil and gas industry contributes to environmental sustainability and scientific and technological advancement through its supply chain activities in the transport and logistics sectors. This paper reviewed the effects of petroleum product transportation at three accident hotspots on Nigeria highway, where traffic and accident records are alarming due to the road axis connecting the southern and northern regions of the country. The preliminary data was statistically analysed to optimise the review process and reduce risk factors through ongoing data monitoring. Studies on Nigeria's petroleum product transportation spills and environmental impacts between the years 2013 and 2023 were critically analysed to generate updated information. The searches include Scopus, PubMed, and Google Scholar. Five hundred and forty peer-reviewed studies were analysed, and recommendations were established through the conclusions. The findings show that petroleum product transport causes heavy metal deposition in the environment as heavy metals damage aquatic life and build up in the food chain, posing a health risk to humans. The study revealed that petroleum product spills have far-reaching environmental repercussions and, therefore, recommended that petroleum product spills must be mitigated immediately. Furthermore, the study revealed that better spill response and stricter legislation are needed to reduce spills, while remediation is necessary to lessen the effects of spills on environmental and human health.

Concentrations and health risk appraisal of heavy metals and volatile organic compounds in soils of automobile mechanic villages in Ogun State, Nigeria

This report presents the findings of the concentrations, distributions and health risks assessment of heavy metals (HMs) and volatile organic compounds (VOCs) in topsoils of two typical automobile mechanic villages (MVs) situated within Ogun State, Nigeria. One of the MVs is located in basement complex terrain (Abeokuta), while the second is in the sedimentary formation (Sagamu). Ten composite samples were collected at depth of 0-30 cm with the aid of soil auger from spent oil-contaminated spots within the two MVs. The chemical parameters of interest were Pb, Cd, benzene, ethylbenzene, toluene, total petroleum hydrocarbon (TPH) as well as oil and grease (O&G). In addition, soil pH, cation exchange capacity (CEC), electrical conductivity (EC) and particle size distribution were also evaluated in order to find out their impacts on assessed soil pollutants. Results revealed that the soils in both MVs are of sandy loam texture, slight acidic to neutral pH, mean CEC < 15 cmol/kg and mean EC > 100 μS/cm. The mean concentration of each of analyzed HMs and VOCs in soils from the two MVs was < 5 mg/kg, while the mean values of TPH and O&G content were > 50 mg/kg. The mean Cd values in soils of both MVs were higher than the national soil screening level of 0.8 mg/kg, but lower than the Canadian and Italian guidelines. There is no significant correlation between each of HMs/VOCs and any of assessed soil physicochemical variables. The non-cancer risk expressed in terms of hazard index (HI) was > 1 via oral ingestion route for adults and children at the two MVs, indicating adverse non-carcinogenic health risk. The HI > 1 value was obtained for adults only through the dermal absorption pathway in Abeokuta MV. However, HI values for the two age groups at the two MVs via inhalation route were < 1, indicating no likelihood of any non-carcinogenic effects via the breathing exposure. The potential of non-cancer risk via oral ingestion route in both MVs was derived from the contributive ratios of HMs and VOCs in the order: Cd > benzene > Pb > toluene. The carcinogenic risk (CR) values due to ingested Cd, benzene and Pb for both age groups at the two MVs exceed the safe limit range of 10-6 to 10-4. Cadmium, benzene and lead made considerable contributions to the estimation of CR through dermal exposure for adults only in Abeokuta MV. The CR values via inhalation pathway for adults and children in both MVs were within the threshold range. Artisans and children should circumvent accidental ingestion of contaminated soils in addition to wearing of protective clothes during routine vehicle maintenance activities.

Characterization, sources, and risk assessment of PAHs in borehole water from the vicinity of an unlined dumpsite in Awka, Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are contaminants of interest in the ecosystem due to associated health risks. Therefore, their detection in the environment is important. In this regard, the risk assessment of PAHs in borehole water near the unlined dumpsite in Anambra State was investigated. Samples of borehole water (16 each) were collected from the study and control areas during both seasons. The PAH concentrations in the borehole water samples were analyzed using gas chromatography. The mean PAH concentration in the study and control samples for the wet season varied from BL-7.65 µg/L to BL-2.98 µg/L, respectively. The study samples' dry season values ranged from BL to 3.33 µg/L, while control samples ranged from BL to 1.87 µg/L. [Formula: see text]PAHs for the wet and dry seasons varied from 5.8 to 13.94 µg/L and 4.25 to 10.09 µg/L for study and control samples, respectively. The four and five rings PAH were the most dominant group in the [Formula: see text] PAHs for the study and control samples, respectively. Diagnostic ratios suggested pyrolytic and petrogenic sources for both locations. The cluster analysis showed different sources of the congeners in the samples. The non-carcinogenic risk showed no possibility of risks via dermal and ingestion routes. In addition, the possibility of cancer risks via ingestion routes was doubtful. The carcinogenic risk index through dermal contact exceeded the acceptable limit for adults and is at a tolerable limit for children, indicating potential threats to humans, with adults more susceptible to cancer risks. Therefore, this study recommends that sanitary dumpsites be constructed for waste disposal and implementation of environmental laws to prevent underground water pollution and the environment.

Ecological and health risk assessment of heavy metals: a case study of residential waste sites in Umuahia, South-East Nigeria

This study assessed the human health hazards and ecological risks of heavy metals from waste sites in residential vicinity. The heavy metals analyzed were Cr, Pb, Cd, Ni, Cu, and Zn. A total of 40 soil samples were collected from waste sites in two residential estates located in the urban and suburb areas of Umuahia, Abia state. Results revealed a trend in concentrations of the heavy metals for both sites in the following order: Cu > Ni > Zn > Cr > Cd > Pb. The concentrations of heavy metals were higher in rural soils than in urban soil. The contamination factor (CF) indices for Pb, Cr, Cu, Ni, and Zn were less than 1 for both sites, signifying a low contamination scenario. The contamination factor for Cd (6 > CF) for both sites indicated a very high contamination status. The estimated degree of contamination (Cdeg) was less than the lower threshold of 8.0, denoting a low degree of contamination. Cd was the highest contributor to ecological risk with Er index value of 184.2 among measured heavy metals. The overall potential ecological risk index for urban and rural sites are 187.1 and 196.1 respectively, classifying the sites as moderate risk. The overall non-carcinogenic hazard index values (HI) for adults and children in urban and rural soils are 0.00248, 0.0198 and 0.0028, 0.0223 respectively, which are below the acceptable limit (HI < 1), indicating that the exposed residents are unlikely to experience any apparent adverse health hazards. However, children are more susceptible to non-carcinogenic hazards than adults in the study areas.

Particulate matter exposure and non-cancerous inhalation health risk assessment of major dumpsites of Oerri metropolis, Nigeria

Numerous particulates are released from the dumpsites in Owerri metropolis and later dispersed to other areas in the environment where they cause adverse health challenges to the inhabitants. To analyze the PM concentrations, field measurements were carried out at seven major dumpsites in Owerri Metropolis. Estimates of the possible health risks as the result of exposure to airborne particulate matter (PM2.5, PM10, etc.) were performed using the United States Environmental Protection Agency (USEPA) human health risk assessment framework. A scenario assessment approach in which normal exposure and worst-case scenario were adopted for acute and chronic exposure periods for infants, children, and adults were carried out. The concentrations of PM2.5 which ranged from 122.30–501.76 μg/m³ at the dumpsites exceeded the WHO 24 hr annual mean maximum exposure limit. The Nigerian National Ambient Air Quality Standard allowable limit for PM10 was exceeded by most of the dumpsites. Hazard quotient > 1 was exceeded for PM 2.5 by nearly all dumpsites and is therefore likely to cause health challenges to people in the vicinity of the dumpsites. The results showed that under monthly conditions, both PM2.5 and PM10 concentration levels at the dumpsites have the potential to cause adverse health effects for infants, children, and adults on acute or chronic bases. Actions should be taken to regulate such PM exposure and to raise public awareness for the inhabitants of the affected areas. In conclusion, regular monitoring is therefore recommended to decrease the ambient particulate matter (PM) concentrations in the study area.