Monitoring Environmental Pathways of Trace Elements in the Northern East Area of Egypt

Abstract

Nile Delta aquifer is one of the largest aquifers worldwide that receives the agrochemical leachates from the surrounding environments. To assess the status of some trace-elements (As, Co Cd, Pb, Cu and Ni) in the North-East area of Egypt, well-water samples beside of surface, subsurface and deep-soil-samples were collected from 17 different locations to represent three environmental-pathways: the first one signifies areas relatively nearby Damietta-branch, while the third pathway stands for the arable lands nearby Ismaellia-canal. The second pathway is in-between these two pathways. Furthermore, a reference soil (irrigated with fresh-Nile-water) was sampled for data comparison. These samples were estimated for their total and AB-DTPA-extractable contents of the aforementioned trace elements (TEs). Results revealed that AB-DTPA-extractable-TEs were in dynamic equilibrium with the corresponding soluble contents in irrigation water. Likewise, AB-DTPA-extractable-TEs significantly correlated with their corresponding total contents in soil. Concentrations of TEs in surface-soil-layer were higher than the corresponding ones in the subsurface and deep-soil-layers. The calculated values of contamination factor indicated moderate to very high levels of soil contamination with TEs. According to principal component analysis, total and AB-DTPA-extractable-TEs in soil were affected by only one-principal-component, recording 86.13 % of the data variance. This indicates that these contaminants originated probably from the same source. Moreover, multivariate-analyses revealed that total TEs significantly and positively correlated with soil hydraulic conductivity and bulk density, while negatively correlated with exchangeable sodium percentage, clay and organic matter contents. These results indicate that the groundwater flow is the potential source that enriched soils with TEs.