Assesment Of Heavy Metal Pollution In Soils And Selected Cereal Crops Grown Around Mugher And Abyssinia Cement Factories, Ethiopia

Abstract

Different researches showed that cement manufacturing is one of the significant sources of heavy metal pollution in soil through precipitation and fallout. In this study, heavy metals pollution in soils and selected cereals (wheat and barley) grown around Mugher and Abyssinia cement factories were investigated. The level of heavy metals from factory effluents also investigated in the Mugher location. A total of 72 soil samples from 0-20cm & 20-40cm depths at different distance from the factory (0-500m, 500-1500m & ≈4000m),44 cereal samples (wheat and barley) and effluents sample were collected and analyzed at Holeta agricultural chemistry laboratory. The parameters analyzed includes: Available Heavy Metals using Ammonium BicarbonateDiethylene Triamine Penta Aceticacid extraction, total Heavy Metals after HNO3-HClO3 digestion and major physico-chemical properties (TN, Oc, K, P, pH, Moisture, soil texture, Bulk density,SO4-S and Cation exchange capacity). Dry ashing method was used to determine the level of heavy metals in cereal samples. Heavy metals from effluents analyzed after HNO3 digestion. Analysis for the concentration of heavy metals; Cu, Cr, Mn, Cd, Fe, Pb, As and Zn were conducted using AAS. One-way ANOVA were used to compare the mean values between treatments (distance b/n the factory) with SPSS statistical software. The Geo-accumulation Index and transfer factor of each heavy metal were computed and interpreted. Except to Pb in Mugher site, the Igeo values are below zero indicates that the soil quality is practically unpolluted. Cd and As were not detected in any of the cereals, soils and effluent samples. The results in soil physico-chemical properties showed that neutral to moderately alkaline soil pH, clay to clay loam soil texture, medium to high category of phosphorus, nitrogen, and potassium; Higher in soil bulk density nearer to the factory. The cement dust therefore effluence to enhance the pH level to the alkaline, as a result the contents of major soil physico-chemical properties declines near to the factory (in Mugher location). Heavy metals level from factory effluent, Mugher location, of Cu, Mn and Cr are above the permissible limit set by FAO use for irrigation activities. The factory therefore should be subject to mandatory monitor and control emanates cement dust & effluent before released to the environment. The values of heavy metals transfer factors from soil to crops are below one indicates that the crops have not influenced by metal pollutions by uptake heavy metals from cement dust polluted areas. The levels of heavy metals determined in the analyzed cereal samples also found to be below the permissible limit set by FAO/WHO; hence, the concentration of these heavy metals in the selected cereals analyzed, may not presently pose a health hazard and can as well serve as sources of essential trace metals to the population.