Evaluation of soil pollution around Mahad AD’Dahab Mine

Mahad AD’Dahab mine was, chosen to study its effect on the surrounding area pollution, as it was the oldest in Saudi Arabia. The objective of this study was to evaluate the degree of contamination of Mahad AD’Dahab soil with respect to heavy metals (As,Be, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, Zn and Hg). One hundred thirty nine soil samples representing three depths from 55 location around the mining area were collected from a transect (0– ≈12 km) closed to the mining area. The collected samples were prepared and analyzed for their contents of above metals. The obtained results indicate that the soils of study area are so much loaded with heavy metals. The total concentrations of heavy metals indicated that most soil samples were significantly polluted (99 %) with one metal or more based on the Enrichment Factor (EF). While the percent of high polluted and very high polluted soil samples were 46 & 33% respectively. Moreover, the physical barriers (e.g. mountains) minimized the hazard of soil heavy metals pollutions. As the EF was > 40 in 41% of the surface soil samples (0–15 cm). While the respective values reached 27 and 23 % in the sub surface layers (15–30 cm) (>30 cm) soil samples, respectively. The concentrations of the studying heavy metals could be arranged in the following order: Cd> Hg > Pb > Zn> Cu > As >Mo >Be. Comparing the obtained results with the international guidelines such as (Scotland, Holland & Chinese), data indicate that, the soil samples were polluted with Cu, Zn, Pb, Cd, Hg & As. Also, the calculated coefficient of variation (CV) shows that the soils of the studying area were highly polluted with heavy metals in the following order: Cd> Zn> Pb> Hg> Cu> Mo. In conclusion, all results indicate that the mining activities at Mahad AD’Dahab were positively contributed to the soil heavy metals pollution in such area. Because of the pollution level reached a dangerous degree, especially in the western area, environmental impact assessment must be applied to minimize the negative effects of heavy metals pollution resulted from industrialization and mining activities under Saudi Arabian conditions

Characteristics of landfill leachates and bio-solids of municipal solid waste (MSW) in Riyadh City, Saudi Arabia

The liquid and bio-solids (landfill sediments) product from landfills has many toxic substances, which may adversely affect on the environmental health. Thus in order to have a better management of characteristics of Riyadh landfill leachates, 80 representative landfill leachate samples were collected and analyzed from February to May 2008. The analysis of landfill leachates includes pH, ECw, concentrations of soluble ions, chemical oxygen demand (COD), total suspended solids (TSS), and heavy metals contents. The obtained results showed that the landfill leachates are characterized by high concentrations of COD (13,900–22,350) mg L−1, TSS of (2280–8912) mg L−1, ECw values of (42.5–58.3) dS m−1 but the pH values ranged 5.49–6.32. Moreover, the leachates had higher concentrations of soluble Na+, K+, Ca2+, Mg2+, Cl−, HCO3- and SO42-. In addition, the leachates contained Fe, Mn, As, Ni, Cr, Zn and Cu in concentrations equivalent to: 104, 11.0, 1.4, 0.6, 0.25, 0.2 and 0.14 mg L−1, respectively. While in the bio-solids (landfill sediments) the average content of Cd, Cr, Cu, Fe, Mn, Mo, Ni and V reached to 10, 242, 234, 48,608, 190, 18, 166 and 24 mg kg−1. The relatively higher variations between the upper and lower limits (maximum and minimum values) of the studying parameters lead to conclude that it is essential to conduct a long-term monitoring program to obtain representative information and this fluctuation should be considered when operating the leachate treatment plant

Spatial variability for some properties of the wastewater irrigated soils

Composite surface soil samples (236 samples) were collected from three fodder farms irrigated for a long period with the treated sewage effluents or well water through a center pivot system. The soil of the 1st farm was loamy sand in texture while it was sandy loam for the other two farms, all were calcareous containing more than 10% of (CaCO3). The average values of EC for the 1st, 2nd and 3rd farms showed to be 3.48, 2.20 and 2.21 dS m−1, respectively. The concentration of Zn was found to be 28.87 mg kg−1 in the 1st farm, while it was 45.96 and 19.51 mg kg−1 in the 2nd and 3rd farms, respectively. The Zn, Cu, Fe and Ni concentrations were higher in the farms irrigated with the treated sewage effluent than their concentrations in those irrigated with well water. The values were 28.87, 16.95, 4225, and 72.26 mg kg−1 for Zn, Cu, Fe & Ni in 1st farm and 42.4, 60.5, 11215, and 180 mg kg−1 for the 2nd farm. The Pb in the soil of the 1st, 2nd and 3rd farms reached 63.01, 37.10 and 27.69 mg kg−1, respectively. It can be concluded that all soil properties except pH had high coefficients of variation, indicating strong variability over space. The data of geo-statistical analysis showed that only TDS and ESP in the 1st farm as well as OM in the 2nd farm had weak spatial dependency while other properties had moderate or strong spatial dependency. Moreover, the TDS and CaCO3 parameters of the 1st and 2nd farms had stronger nugget effects