Elemental composition and potential health risk of vegetable cultivated in residential area situated close to abandoned gold mine dump: Characteristics of soil quality on the vegetables.

The presence of toxic metals in residential areas near abandoned gold mine tailings is a major environmental issue. This study mainly aimed to investigate the elemental distribution of both toxic and essential elements in soils and leafy vegetables (Brassica oleracea) collected from eight different sites around the Davidsonville residential area, located closer to the abandoned Princess gold mine dump, Johannesburg, South Africa. The nutritional value of vegetables in the human diet was determined to assess their value to their health. The vegetables contained metals in the following descending order: Ca > Mg > Ca > Sb > Pb > Fe > Mo > Cr > Se > As > V > Ni > Co > Cd. The bioaccumulation factor (BAF) revealed that vegetables tend to accumulate most metals even (toxic) during the transfer and translocation process. Based on the recommended daily allowance (%RDA) the vegetables showed to contribute 152%, 84% and 75% toward RDA for Se, V and Ca, respectively for most adults and these play a role in human metabolic activities. The vegetables were found to be a good source of essential elements (Ca, Mg, Ni, Na, Fe) but with some traces of toxic metals such as Pb, As and Sb. Based on the health risk assessment, the vegetable posed an adverse health hazard for human consumption due to metals with high HRI >1.

Determination of polycyclic aromatic hydrocarbons (PAHs) in river water samples from the Vaal Triangle area in South Africa.

PAHs are fused ring aromatic pollutants some of which are highly carcinogenic to humans and are persistent in the environment. The objective of this study was to develop a suitable extraction method for PAHs from river water samples, identify and quantify the individual compounds. An optimized reverse solid phase extraction (SPE) method was used after conditioning the sorbent to extract and preconcentrate compounds of polycyclic aromatic hydrocarbons (PAHs) in river water samples. The following ten compounds were identified and quantified with a High Performance Liquid Chromatographic technique (HPLC): naphthalene (Naph), acenaphthylene (Ace), phenanthrene (Phe), anthracene (Anth), fluoranthene (Fluo), benzo(b)fluoranthene (BbFl), benzo(k)fluoranthene (BkFl), benzo(a)pyrene (BaPy), dibenzo(a,h)anthracene (DiAn) and indeno(1,2,3-cd)pyrene (InPy). An LC-18 sorbent showed good recoveries after extracting PAHs standard mixture of 1.0 mg/L. The best performing eluting solvent was acetone and very good percentage recoveries that ranged from 97.17-101.18% were obtained for seven compounds. Poor recoveries were also obtained for Fluo (1.03%), BbF1 (0.22%) and BkF1 (0.7%). The standard deviation ranged from 0.05 to 2.26 and the detection limits of less than 0.2 were obtained. Average concentration ranges of PAHs identified within the study area were: Naph (0.0339-0.0382 mg/L) at the Klip river site; Ace (00815-0.0828 mg/L) at Vaal river, (0.0538-0.0591 mg/L) at Klip river and (0.001-0.0073 mg/L) at Vaal barrage; Phe (0.0214-0.0263 mg/L) at Vaal river, (0.0487-0.0521 mg/L) at Klip river and (0.3837-0.4373 mg/L) at Vaal barrage; Anth (0.0073-0.0092 mg/L) at Vaal river, (0.3582-0.4072 mg/L) at Klip river and (0.3457-0.4022 mg/L) at Vaal barrage; Fluo (0.0985-0.1205 mg/L) at Vaal river, (0.0552-0.0593 mg/L) at Klip river and (0.1321-0.1612 mg/L) at Vaal barrage; BbFl (0.0681-0.1151 mg/L) and InPy (0.2561 ± 0.3067 mg/L) at Vaal barrage sites only. Benzo(k)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were not detected. The obtained data will be useful as baseline information when similar studies are undertaken in the future and could also be useful to policymakers.

Characterization of PM10 samples from Vanderbijlpark in South Africa.

In this study, mass concentrations and physico-chemical characteristics of suspended particulates of aerodynamic size 10 µm (PM10) were evaluated. A dual E-Sampler which combines the light scatter and the gravimetric filter methods was used. Sampling occurred between August and December 2009. Scanning Electron Microscope - Energy Dispersive Spectrometry (SEM-EDS) and Inductively Coupled Plasma 6000 were used for elemental and physical characterization. The highest daily average mass concentration measured was 0.03543 mg/m(3) and was below the international and national daily limit of 0.150 mg/m(3), as well as the strict Vaal Triangle regional standard of 0.075 µg/m(3). Relatively high daily average mass concentrations were obtained during the winter period. Concentrations of evaluated heavy metals decreased in the following order: iron (Fe) > manganese (Mn) > zinc (Zn) > copper (Cu) > vanadium (V) > titanium (Ti) > nickel (Ni) > lead (Pb). Positive correlations were established between Zn and Pb (r = 0.916); Zn and Mn (r = 0.883); Zn and V (0.984); Zn and Ni (r = 0.877); Zn and Fe (r = 0.914), which suggests common sources. However, Zn and Ti (r = 0.522); Zn and Cu (0.781) were poorly correlated.