A comprehensive investigation of geoenvironmental pollution and health effects from municipal solid waste landfills

This study investigates human health risks associated with heavy metals (HMs) occurrence in municipal solid waste (MSW) landfills. For testing of selected MSW landfills steps were involved, including site characterization, soil sampling and chemical testing, statistical analysis, as well as health risk assessment, carcinogenic and non-carcinogenic effects. For the Polish landfill (Radiowo) the average HMs concentrations were found in the following order: Zn (52.74 mg/kg DM) > Pb (28.32 mg/kg DM) > Cu (12.14 mg/kg DM) > Ni (4.50 mg/kg DM) > Cd (3.49 mg/kg DM), while for the Czech landfill (Zdounky): Zn (32.05 mg/kg DM) > Cu (14.73 mg/kg DM) > Ni (4.73 mg/kg DM) > Pb (0.10 mg/kg DM) = Cd (0.10 mg/kg DM). Strong positive correlations between selected HMs demonstrated identical origins. Principal component analysis (PCA) performed for the Radiowo landfill transferred the soil parameters into three principal components (PCs), accounting for 87.12% of the total variance. The results of the PCA analysis for the Zdounky landfill revealed three PCs responsible for 95.16% of the total variance. The exposure pathways of HMs for landfills were in the following order: ingestion > dermal absorption > inhalation. For both landfills, the values of hazard quotient were lower than 1, indicating no potential negative health effects. In terms of the hazard index (HI), for both landfills, no adverse human health effects occur (HI < 1). The incremental lifetime cancer risk (ILCR) values indicated negligible or acceptable carcinogenic risk of HMs (average ILCR in the range from 5.01E-10 to 5.19E-06).

Assessment of heavy metals concentration in soils and plants from electronic waste dumpsites in Lagos metropolis

E-waste is a global environmental problem that must not be underestimated. To ascertain the environmental pollution status of electronic waste dumpsites, an assessment of seasonal variation in concentrations of heavy metals in the soils and plants in electronic waste dumpsites in Lagos metropolis was undertaken during the two major seasons (wet and dry seasons) in Nigeria. The soils and plants samples collected in August during the rainy season and December during the dry season were digested using aqua regia, a wet digestion method. The heavy metal concentrations were quantified with flame atomic absorption spectrophotometer (FAAS) fitted with a hollow cathode lamp (Perkin-Elmer AA Analyst 200) using an air-acetylene flame. The soil samples and the plants analyzed were found to have high concentrations of heavy metals. All the plants analyzed were identified and classified as excluders and accumulators of heavy metals based on their shoot/root quotients. The results obtained experimentally were analyzed using statistical and multivariate techniques. The soil quality of the study area was evaluated using correlation factor, pollution load index, and geoaccumulation index. The heavy metal assessment in comparison with the EU and Canadian standards for both agricultural and residential soils showed that the e-waste dumping sites are highly polluted. The results obtained for both the soil and plants analyzed confirmed the great impact of the hazardous components of e-waste on the ecosystem.

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

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.

Quantitative assessment of metal contamination and associated pollution risk in sediments from the Mara River in Tanzania

For most rivers in sub-Saharan Africa, information about pollution indices related to sediments is sparse. Sedimentological research of rivers that empty into Lake Victoria is highly patchy and wide apart. The present study determined the levels and associated risk of As, Cd, Cr, Hg, and Pb in sediments collected from four different sites along the Mara River that empties into Lake Victoria in Tanzania. Samples were collected in the dry and rainy months in 2019. Pollution indices, namely geo-accumulation index (I_geo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (E_rⁱ), and potential ecological risk index (RI) were used to evaluate the influence of heavy metal contamination in sediments. Dry month mean concentrations, in milligram per kilogram, of heavy metals were as follows: As (11.04 ± 0.13), Cr (1.02 ± 0.29), Cd (0.43 ± 0.05), and Hg (0.01) in the dry month. Respective sediment heavy metal concentrations for the rainy month were 22.22 ± 0.05 mg As/kg, 3.84 ± 0.34 mg Pb/kg, 1.53 ± 0.15 mg Cd/kg, 1.43 mg Cr/kg, and 0.03 mg Hg/kg. Generally, the risk indices showed high values in the rainy month and low values in the dry month, especially for As and Cd-an indication of anthropogenic influence. Correlation coefficient analysis for Pb and Cd showed a strong positive correlation (r = 0.99, p < 0.01)-this may suggest a similar source or similar transport behavior. Special attention needs to be paid with regard to rainy season As and Cd enrichment in the study area.

Hydrochemical Processes and Isotopic Study of Geothermal Springs within Soutpansberg, Limpopo Province, South Africa

Geothermal springs and boreholes within the Soutpansberg Group were sampled and analysed for their major ion chemistry and stable isotope compositions in order to ascertain the possible sources and geochemical processes of the waters. The temperature of the geothermal springs ranges from 41 °C to 49 °C (thermal/hot waters) and 53 °C to 69 °C (scalding/hyperthermal waters). The major water types are Na-Cl and Na-HCO3, which are typical of marine and deep groundwaters influenced by ion-exchange processes. The hydrochemical parameters suggest that thermal gradient, carbonate weathering, mineral dissolution, ion exchange, and evaporation are the main geochemical processes controlling the geothermal springs. The δ18O and δ2H values vary from −5.82‰ to −4.82‰ for δ18O and −33.5‰ to −24.6‰ for δ2H for all the geothermal spring water. The isotopic ranges of the groundwater are relatively smaller and more depleted than those of rainwater (δ2H = −9.8‰ and δ18O = −2.7‰). The δ2H and δ18O signatures reveal a significant infiltration before evaporation. The δ2H and δ18O values further confirm that the waters are of meteoric origin, which implies that modern rainfall is the fundamental component of recharge derived from the infiltration of local precipitation with significant contribution of another type of water in the deeper part of the aquifer. These results provide further insight into this basement aquifer, which is a vital resource for the region.

Environmental assessment of mining industry solid pollution in the mercurial district of Azzaba, northeast Algeria

To date, there have been few detailed studies regarding the impact of mining and metallogenic activities on solid fractions in the Azzaba mercurial district (northeast Algeria) despite its importance and global similarity with large Hg mines. To assess the degree, distribution, and sources of pollution, a physical inventory of apparent pollution was developed, and several samples of mining waste, process waste, sediment, and soil were collected on regional and local scales to determine the concentration of Hg and other metals according to their existing mineralogical association. Several physico-chemical parameters that are known to influence the pollution distribution are realized. The extremely high concentrations of all metals exceed all norms and predominantly characterize the metallurgic and mining areas; the metal concentrations significantly decrease at significant low distances from these sources. The geo-accumulation index, which is the most realistic assessment method, demonstrates that soils and sediments near waste dumps and abandoned Hg mines are extremely polluted by all analyzed metals. The pollution by these metals decreases significantly with distance, which indicates a limited dispersion. The results of a clustering analysis and an integrated pollution index suggest that waste dumps, which are composed of calcine and condensation wastes, are the main source of pollution. Correlations and principal component analysis reveal the important role of hosting carbonate rocks in limiting pollution and differentiating calcine wastes from condensation waste, which has an extremely high Hg concentration (˃1 %).