Baseline concentrations of trace elements in surface soils of the Torrelles and Sant Climent Municipal Districts (Catalonia, Spain)

An investigation was conducted to study the baseline levels of Ba, Cd, Cu, Cr, Ni, Pb, Sr, V and Zn ( aqua regia-extractable) based on 51 representative soils of the Torrelles and Sant Climent Municipal Districts ( Catalonia, Spain). The baseline concentrations of those elements were (mg kg(-1)): Ba 73.9-617.9, Cr 9.2-120.2, Cu 4.0-111.6, Ni 6.1-118.6, Pb 5.6-217.5, Sr 19.6-128.8, V 12.1-101.2, and Zn 16.8-326.8, respectively. Forty-nine samples were reported as having less than the 0.67 mg kg(-1) detection limit for cadmiun and were therefore not useful for baseline determination; however, these results suggest that the baseline average is probably below 0.67 mg kg(-1). Upper baseline values for most of the elements corresponded with those reported in the literature, except for Pb and Zn, which were two to four times greater. Soil properties, including clay fraction, OC, CEC and pH(w) were related to metal concentration using correlation and factorial analysis. R-mode factor analysis separates the soil analysis data into three factors. These factors explain 67.3% of the total variance, suggesting that metal concentration was controlled by soil composition.