Evaluation of metals that are potentially toxic to agricultural surface soils, using statistical analysis, in northwestern Saudi Arabia

© 2015, Springer-Verlag Berlin Heidelberg. Heavy metals in agricultural soils enter the food chain when taken up by plants. The main purpose of this work is to determine metal contamination in agricultural farms in northwestern Saudi Arabia. Fifty surface soil samples were collected from agricultural areas. The study focuses on the geochemical behavior of As, Cd, Co, Cr, Cu, Hg, Pb and Zn, and determines the enrichment factor and geoaccumulation index. Multivariate statistical analysis, including principle component analysis and cluster analysis, is also applied to the acquired data. The study shows considerable variation in the concentrations of the analyzed metals in the studied soil samples. This variation in concentration is attributed to the intensity of agricultural activities and, possibly, to nearby fossil fuel combustion activities, as well as to traffic flows from highways and local roads. Multivariate analysis suggests that As, Cd, Hg and Pb are associated with anthropogenic activities, whereas Co, Cr, Cu and Zn are mainly controlled by geogenic activities. Hg and Pb show the maximum concentration in the analyzed samples as compared to the background concentration

دراسة تلوث الأراضي الزراعية في غور الأردن بالمعادن الثقيلة باستخدام تحليل الأنحدار ي

Geochemical analysis were performed in lower subsurface soil samples of 10,20,30 and 40cm depth, collected from seven regions in the northern Jordan valley. Eighteen descriptors (variables) for each sample were used. Among them were metal ions concentrations, such as Pb, Ti, Co, Zn, Mg, Fe, Na, K, Al, Cu, Si, and Mn. Other variables were pH, EC, and TDS. The soils in the study area are found to be alkaline since the pH value ranging between 9.2 - 9.5. Location 6 shows the highest TDS value, that's 1219.2 ppm. All the locations show high concentration ofPb, ranges between 50 (loc.l) to 150 ppm (loc.6). Zn values shows high concentration almost in all the locations, 100 (loc.l) to 300 ppm (loc.5 and 7). The Cd concentration very high in locations, 1,2,3 and 4 with ranges between 4 to 6.9 ppm. Ti concentration ranges between 3700 (loc.5 and 7) to 12300 ppm (loc.l).The sources of this increase, may be attributed to the water used in irrigation, fertilizers and the different types of pesticides, as indicated by the chemical and regression analysis.أتمت التحاليل الجيوكيميائية لعينات التربة على أعماق . ( و 20 و 30 و45 سم والتي تم جمعها من سبعة مواقع مختلفة في غور الأردن الشمالي ، ولقد تم إستعمال ثمانية عشر متغيراً كيميائياً منهم AL, K, Na, Fe, Mg, Zn, Co, Ti, Pb, Si, Mn, بالإضافة إلى المتغيرات الأخرى pH,Ec, TDS ولقد وجد بعد دراسة النتائج أن معظم المواقع أظهرت زيادة في التراكيز خاصة على الأعماق الأولى ، أسباب هذه الزيادة قد يكون مصدره المياه المستخدمة فما الري ، الأسمدة ، المبيدات أو التركيب الجيولوجي للمنطقة

Fluoride dynamics in the granitic aquifer of the Wailapally watershed, Nalgonda District, India

High concentrations of fluoride (up to 7.6 mg/L) are a recognized feature of the Wailapally granitic aquifer of Nalgonda District, Andhra Pradesh, India. The basement rocks provide abundant sources of F in the form of amphibole, biotite, fluorite and apatite. The whole-rock concentrations of F in the aquifer are in the range 240–990 mg/kg. Calcretes from the shallow weathered horizons also contain comparably high concentrations of F (635–950 mg/kg). The concentrations of water-soluble F in the granitic rocks and the calcretes are usually low (1% of the total or less) but broadly correlate with the concentrations observed in groundwaters in the local vicinity. The water-soluble fraction of fluoride is relatively high in weathered calcretes compared to fresh calcretes. Groundwater major-ion composition shows a well-defined trend with flow downgradient in the Wailapally aquifer, from Na–Ca–HCO3-dominated waters in the recharge area at the upper part of the catchment, through to Na–Mg–HCO3 and ultimately to Na–HCO3 and Na–HCO3–Cl types in the discharge area in the lowest part. The evolution occurs over a reach spanning some 17 km. Groundwater chemistry evolves by silicate weathering reactions, although groundwaters rapidly reach equilibrium with carbonate minerals, favouring precipitation of calcite, and ultimately dolomite in the lower parts of the watershed. This precipitation is also aided by evapotranspiration. Decreasing Ca activity downgradient leads to a dominance of fluorite-undersaturated conditions and consequently to mobilisation of F. Despite the clear downgradient evolution of major-ion chemistry, concentrations of F remain relatively uniform in the fluorite-undersaturated groundwaters, most being in the range 3.0–7.6 mg/L. The rather narrow range is attributed to a mechanism of co-precipitation with and/or adsorption to calcrete in the lower sections of the aquifer. The model may find application in other high-F groundwaters from granitic aquifers of semi-arid regions

Contaminação provocada por um depósito de lixo no aqüífero Alter do Chão em Manaus - AM Contamination provoked by a garbage dump in the Alter do Chão aquifer in Manaus-AM

Este trabalho discute a composição química da água do aqüífero Alter do Chão na área do entorno de um lixão na cidade de Manaus. Foram analisados pH, Eh, turbidez, nitrato, nitrito, amônia e os elementos Cl, F, Si, K, Na, Ca, Mg, Al, As, Mn, P, Sb, Ba, Cr, Fe, Se, Sn, Cd, Cu, Pb e Zn, em dois períodos, no final do período chuvoso e na estiagem, em 18 poços e cacimbas. De acordo com os resultados obtidos, a água está comprometida para consumo humano na quase totalidade dos poços amostrados, em conseqüência dos elevados teores de Al, Fe, As, Cd, Pb, Sb e Se, dos compostos nitrogenados e também por contaminações pontuais de Mn e Zn. A pluma de contaminação, que se expande no final do período chuvoso, estende-se para leste e sudeste do lixão, em função das direções naturais de fluxo do aqüífero e do baixo potenciométrico gerado pelo igarapé que corta a área.<br>The present paper deals with the chemical composition of water from deep and shallow wells and water- holes near a garbage dump in the city of Manau. pH, Eh, turbidity, nitrate, nitrite, ammonia and the elements Cl, F, Si, K, Na, Ca, Mg, Al, As, Mn, P, Sb, Ba, Cr, Fe, Se, Sn, Cd, Cu, Pb and Zn were analysed at the end of the rainy season and in the dry period in 18 wells. In almost all wells the water is no longer suitable for human consumption due the high contents of Al, Fe, As, Cd, Pb, Sb and Se, nitrogen compounds and local contaminations by Mn and Zn. The contamination plume, which expands at the end of the rainy season, extends to the east and southeast of the garbage dump on account of the natural directions of the aquifer flow and the potenciometric low level generated by the stream flow cutting through the area