No abstract

Daily exposure to potentially toxic elements (heavy metals) through the oral ingestion of water has been a major concern to human health due to its detrimental effects. Studies focusing on health risk assessment of potentially toxic elements in surface and ground waters have been conducted, but none has been reported in Njaba River. Few studies conducted have focused only on the assessment of its water quality. Therefore, this study assessed the carcinogenic and non-carcinogenic effects of the potentially toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) in Njaba River. Overall, a total of 135 water samples was collected for this study and were analyzed using Agilent FS240AA AAS. The potentially toxic elements concentrations were: As (0.015±0.001 to 0.021±0.001 mg L-1), Cd (0.006±0.002 to 0.018±0.002 mg L-1), Cr (0.027±0.001 to 0.074±0.001 mg L-1), Cu (0.016±0.002 to 0.033±0.001 mg L-1), Ni (0.031±0.001 to 0.053±0.002 mg L-1), Pb (0.050±0.002 to 0.092±0.001 mg L-1), and Zn (0.061±0.002 to 0.097±0.002 mg L-1). As, Ni and Pb recorded concentrations above their respective maximum permissible limits. Physicochemical parameters were appraised using the American Public Health Association standard method (APHA). The evaluation of the carcinogenic and non-carcinogenic health risks of the analyzed elements was carried out based on the guidelines of the USEPA. The hazard index values for children via upstream, midstream and downstream sample points were 0.0000128, 0.00000895 and 0.0513 respectively, while the hazard index values for adults via upstream, midstream and downstream sample points were 0.00000551, 0.00000395 and 0.00000581 respectively. The health risk estimation showed that the hazard quotients were within acceptable limits. The total cancer risks of potentially toxic elements were generally within the range of tolerable risk for adults and above the range of tolerable risk for children.

No abstract

Discriminating contaminant sources is crucial for pollution control. The study aimed at identifying the source(s) of heavy metals in active dumpsite soils from selected areas in Southeastern Nigeria using statistical tools. The dumpsites were Enyimba dumpsite Aba (dumpsite-1), Okpuno-Egbu dumpsite Nnewi (dumpsite-2), Rice mill dumpsite Abakaliki (dumpsite-3) and Nekede dumpsite Owerri (dumpsite-4) in Abia, Anambra, Ebonyi and Imo State respectively. After standard sampling, elemental analysis was carried out using an energy dispersive x-ray fluorescence spectrometer; Chromium (Cr), Manganese (Mn), Cobalt (Co), Iron (Fe), Nickel (Ni), Copper (Cu), Zinc (Zn), Arsenic (As), Lead (Pb) and Cadmium (Cd) were quantified and results showed they were present in high concentrations above control and standard values set by the National Environmental Standards and Regulations Enforcement Agency (NESREA) and the Food and Agriculture Organization of the United Nations (FAO) / World Health Organization (WHO). Metals investigated exhibited variable correlations among themselves suggesting potential multi-element contamination, while soil organic matter (OM) and pH displayed both significant positive and negative influence on the metal availability in the studied soils. Test of significance of the observed correlation were positive and significant (r > 0.9 at p < 0.05/0.01) for Cr/Co, Cr/Fe, Mn/Co, Co/Fe, Cu/Zn, Zn/Pb, Cu/As, Cu/Pb, Zn/As, As/Pb in dumpsite-1; in dumpsite-2, only Ni/Cu; in dumpsite-3, Fe/OM and Cd/OM while in dumpsite-4,Co/Fe, Cu/As, Cu/Pb, Zn/Cd, Ni/OM, and As/Pb. Hierarchical cluster analysis (HCA) and Principal component analysis (PCA) extracted two to three components/groups based on square Euclidean distance and eigenvalues > 1, confirming sources to be from organic pigments in plastics, scrap metals and incinerated biodegradable wastes. This study concludes that statistical methods can provide a scientific basis for monitoring heavy metals accumulation in dumpsite soils.

The level of heavy metals (Fe, Cu, As, Pb, Cd, Mg, Ca, Hg, Ni, Cr, Zn, Ag, Co, Mo, Se and Al) in soils and food crops (okra, cassava and rice) cultivated within selected mining sites in Ebonyi State, Nigeria were determined using FS240AA Atomic Absorption Spectrophotometer (AAS) according to the method of American Public Health Association (APHA). Soil samples were collected from Enyigba mining site, Ikwo mining site, AmeriAmekamining site, Izza mining site, MkpumeAkwatakwa mining site and MpumeAkwaokuku mining site while the food crop samples (okra, cassava and rice) were collected from the farmlands within the mining sites. Control samples were collected 500m away from the mining destinations were there was no evidence of mining activities on the soils. A total of sixty sub-samples and six control soil samples were collected for this study. Generally, the values of all the heavy metals analyzed for soil and food crop samples were higher than the values recommended by the World Health Organization (WHO), and those from the control site suggesting possible mobility of the metals from mining sites to farmlands through leaching and runoffs. The findings in this study also revealed that the food crops contain heavy metals exceeding the maximum permissible concentration, and could be detrimental to human health when they are consumed.

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. $$\sum$$ ∑ 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 $$\sum$$ ∑ 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.

No abstract

The level of heavy metals (Pb, Cd, As, Cr, Ni, Co, Zn) and physicochemical parameters in borehole water sources within selected mining sites in Ebonyi State, Nigeria were determined using FS240AA Atomic Absorption Spectrophotometer (AAS) according to the method of American Public Health Association (APHA). Water samples were collected from Enyigba mining site, Ikwo mining site, Ameri Amekamining site, Izza mining site, Mkpume Akwatakwa mining site and Mpume Akwaokuku mining sites. Composite water samples were collected within the mining locales and 500 metres away from the mining locations using two liters plastic jars. Similarly, the control samples were taken from Abakaliki (about 15 km away from mining area) where there was no evidence of mining activity. A total of 14 sub-samples were collected for this study. Generally, the levels of heavy metals in the borehole water samples were higher than the values recommended by the World Health Organization (WHO). This however suggests a possible mobility of the metals from mining sites into the groundwater sources through leaching. The findings from this study have revealed the need to purify borehole water within mining areas prior to industrial and domestic use.