Statistical Distribution of Geochemical Elements in Stream Sediments and the Influence of Flood Phosphate Mud on the Mining Area, Metlaoui, Southwest Tunisia

Abstract

In this study we elucidated the relationships between geochemical composition of the stream sediment samples and industrial pollution (phosphate mud flood). We offered an approach based on multivariate statistics: the factor analysis with a series of factor score of the investigated area. This type of numerical analysis, applied to 21 samples of surveyed Metlaoui stream, should also offer an additional insight into the possible anthropogenic impacts that might be present in the stream sediment geochemistry. The model is presented in the form of a variance factor matrix in which the four factors explain almost 90% of the total system variability. As can be seen from the statistics results, the first factor (F1) predominates and accounts for almost twice as much of the total explained percentage variance as the second (F2). The other factors show a decline in magnitude (F3 and F4). Three main metal associations were individualised in the stream sediment of Metlaoui. Ti–Zr; Fe–Mn and Zn–Ni–Cu–Mo. The increase of all concentration values (Ti, Zr, Fe, Mn, Zn, Ni, Cu and Mo) reflects that the mining activity (phosphate mud flood, or airborne deposition) could be associated with Fe–Mn oxyhydroxide that play a significant role in precipitating and thus fixing heavy metals in the proximity of mine contamination source.