Levels of toxic elements in soils of abandoned waste dump site


Nnenna E. Okoronkwo, nnennaejijeokoronkwo@yahoo.com1, A. O. Ano2, Jude C. Igwe, jcigwe2001@yahoo.com1, E. C. Onwuchekwa, elenduco@yahoo.com3, and I. Nnorom4. (1) Industrial Chemistry, Abia State University, Uturu, 31 Pound Road, Aba, Aba, 234, Nigeria, (2) Soil Science, National Root Group Research Institute, Umudike, Staff Quarters, Umudike, Umuahia, 234, Nigeria, (3) Microbiology, Abia State University, Uturu, 23 Lomara Lane, Okigwe, Okigwe, Imo State, 234, Nigeria, (4) Industrial Chemistry, Abia State University, Timber Line, Umuahia, Umuahia, Abia State, 234, Nigeria
The soils of an abandoned waste dumps sites which has been presently used for crop cultivation was investigated. Three points on the location were selected and three pits of 100cm depth were dug at selected points. Soils samples were collected at an interval of 10cm from each pits. The physico-chemical properties and toxic elements (As, Cd, Cr, Ni and Pb) levels were determined. The results showed that the mean percentage of sand, silt and clay were 75.012.31, 12.870.93, and 10.451.47 respectively while the mean pH was 6.890.01. The mean percentage organic matter content were high and was 3.470.41. The mean exchangeable Ca, Mg, K and Na in Meq/100g of soil were 4.200.42, 3.410.32, 0.310.004 and 0.470.006 respectively. The mean exchangeable acidity (EA) and exchangeable AI were 0.230.002 and 0.690.004 respectively. Of all the five toxic elements studied, the highest mean concentration (mg/kg) of 133.7410.60 was recorded for Pb followed by Cr (22.273.03), Ni (8.140.33) and As (5.970.32)while the least mean concentration of 1.640.11 was recorded for Cd. The toxic elements were examined for dependency upon some soil factors through the use of correlation analysis, sand, organic matter and effective cation exchange capacity (ECEC) correlated significantly and positively with Cr, Pb indicating that these factors largely control the concentration of these elements in the soils.

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