Heavy metal contamination in soil and groundwater around industrial areas of Kollam District, Kerala, India

The present study was intended for assessing the contamination level of various heavy metals in surface soil and groundwater around the automobile workshops situated at different locations in the Kollam District of Kerala state, India. The procured soil and groundwater samples were analyzed for cadmium, zinc, iron, lead, nickel, chromium, copper, manganese, and arsenic using atomic absorption spectrophotometer by following standard procedures. The contamination level of these metals was assessed using the pollution indices like enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). The results revealed that the concentrations of all analyzed metals in the surface soils of the automobile workshops were higher than the control. On the contrary, the concentration of no heavy metal in the groundwater was either equal to or higher than the limit prescribed by WHO. However, the concentration levels of Fe, Pb, Cu, and Zn were either equal to or higher than the control values. Based on the Igeo, CF, and EF, it was found that the contamination intensity of the heavy metals in soil decreased in the following order: Fe > Pb > Cd > As > Cr > Zn > Cu > Ni > Mn. From the results of PLI, it was interpreted that the sampling sites S2, S4, and S5 were highly polluted. Non-contamination of underground water from the age-old workshops is the uniqueness of the present study against the other studies, which were completed in alluvial formations with inverse results. In the studied region, the groundwater is stored in the hard rock formations and its hydraulics remains different from alluvial aquifers.

Assessment of the geo-environmental effects of activities of auto-mechanic workships at Alaoji Aba and Elekahia Port Harcourt, Niger Delta, Nigeria

Geo-environmental assessment of activities of auto–mechanics at Alaoji Aba and Elekahia Port Harcourt, both in the Niger Delta region, Southern Nigeria were carried out with the main objective of determining the extent of soil contamination arising from anthropogenic activities within mechanic villages (MVs). Geochemical analysis of soil samples from the study area revealed that the concentrations of the trace metals ranged from <1 mg/kg for chromium (Cr) to 1,925 mg/kg for the lead (Pb). Soil analysis for polycyclic aromatic hydrocarbon (PAH) and total petroleum hydrocarbon (TPH) across the area revealed concentrations ranging from <0.02 to 1.80 mg/Kg and from <1.00 to 38,327 mg/kg respectively. Elevated levels of the heavy metals and TPH were observed at MV in Alaoji Aba when compared to MV in Elekahia Port Harcourt, and the control sites. These could be attributed to contamination due to the presence of these auto-mechanics in the area for over thirty years. The concentration of Pb and Cd recorded in some sample points were above USEPA (United State Environmental Protection Agency) and the National Environmental Standards and Regulations Enforcement Agency (NESREA) permissible limits. Results of PAH analysis showed the presence of naphthalene, phenanthrene, pyrene, fluorene, benzo(a)anthracene, acenaphthene, methylnaphthalene. Risk assessment analysis showed significant geo-accumulation values for Cd and Pb indicating heavy contamination. The monomial risk factor of the heavy metals in the MVs are in the order Cd >Pb>Cr, while potential ecological risk index analysis showed values indicating very high risk, considerable risk and a moderate risk to the area under study as well as the surrounding environment. These results suggest that the soils from the MVs which represent the mechanic workshops at Alaoji Aba and Elekahia Port Harcourt are considered to be of pollution concern due to elevated Pb and Cd levels. Hence, there is a serious need to regularly monitor the activities of auto-mechanics in the study area.

Evaluation of tourism impact on soil metal accumulation through single and integrated indices

Recently, surface soils of remote or protected areas, that receive pollutants from the surroundings or in situ activities through dry and wet deposition, exceed the baseline content of heavy metals. In the last decades, the use of single and integrated indices is a powerful tool to process, analyze and convey information about metal accumulation degree for decision makers to better manage protected areas. Single indices provide information about only one metal, whereas the integrated ones give a holistic evaluation. The aim of the research was to assess the temporal trends of three single (Contamination Factor, Enrichment Factor and Geo-accumulation Index) and two integrated (Pollution Load Index, Nemerow index) indices in order to evaluate if the touristic impact caused soil metal (Cr, Cu, Ni and Pb) accumulation. In autumn 2016 and in spring 2016 and 2017, the surface soils (0-10 cm) were collected at eight sites inside the Vesuvius National Park (Southern Italy), characterized by intense tourism from spring to autumn. The metal concentrations were measured in the soils and used to calculate the indices. In addition, the Ecological Risk Factor was calculated and the phytotoxicological assays were performed. The findings showed that the surface soils of the Vesuvius National Park were polluted by Cr, Cu, Ni and Pb, according to both single and integrated indices. The touristic impact would seem to be the main cause of soil metal accumulation, as the highest values of the calculated indices were detected for samples collected at the end of the touristic season and the lowest at the beginning of the touristic season. Anyway, Cu and Pb would seem also to derive by ex situ anthropogenic sources, whereas Cr and Ni also by natural sources, such as spontaneous fires and substrate weathering. Finally, the soils showed phytotoxic effects and low ecological risks.

Ecological risk assessment of trace elements in sediment: A case study from Limpopo, South Africa

This study aimed to determine the ecological risk posed by metals, in sediments from the Nyl River system in Limpopo, South Africa. Metals were extracted from sediment samples by aqua regia microwave digestion and were analysed using standard ICP-OES techniques. The ecological risk indices applied to the data included Contamination Factor, Pollution Load Index, Geo-accumulation Index and Enrichment Factor. The results showed that the levels of Ni at STW and NYL in the HF period exceeded the Canadian Sediment Quality Guidelines by a factor of 1.36 and 1.83 respectively whereas NYL and MDD had 2.57 and 1.32 times the allowed limit of Ni in the LF period. During the HF period, the GC site exceeded the allowed limit of Zn by a factor of 1.04 and NYL had 1.21 times the allowed Zn in the LF period. The levels of metals are generally low near the origin of the river and increase moving downstream. The levels of metals in the Nyl River floodplain, a Ramsar accredited wetland, were high with CF scores ranging between 0.905 and 5.82, Igeo values with a range of -0.541 to 2.441 and EF scores ranging from 0.959 to 6.171. and posed a greater risk than the other sites. This indicated that the wetland is performing its ecological function by trapping and removing toxins from the water body. The Pollution Load Index determined that the Golf Course (PLI=4.586) and STW (PLI=2.617) sites were polluted only in the low flow period whereas the Nyl River floodplain (HF PLI=79.845; LF PLI=30378.768) and Moorddrift Dam (HF PLI=1.903; LF PLI=9.256) sites were polluted in high flow and low flow periods.