Abstract
In order to evaluate the loadings of some agricultural soils with heavy metals, field studies were made across the Iasi County. The heavy metals concentration range were as follows: 15.4 - 36 mg/kg (Cu), 49 - 115 mg/kg (Zn), 7.4 - 20.4 mg/kg (Pb), 0.13 - 0.43 mg/kg (Cd), 6.9 - 13.15 mg/kg (Co), 25 - 100 mg/kg (Ni) and 463 - 798 mg/kg (Mn), respectively. The median of the heavy metals decreased in the next order: Mn (589) ] Zn (67) ] Ni (46) ]Cu (22,1)]Pb (12.1)]Co (10.2)]Cd (0.32). The studied heavy metal median was higher than the same metal median from European soils. According to the Romanian legislation, the normal values are exceeding in 13% the samples for Zn, 73% for Cu, 93% for Ni, and in one case, the value of Ni exceeded the alert threshold (75 mg/kg). A direct relationship between Cu, Pb, Zn and Co was noticed, which may indicate a common source of these metals. The Pearson`s coefficients of these elements were: Pb-Cu (0.863), Cu-Zn (0.826), Pb-Zn (0.74), Cu-Co (0.730), Pb-Co (0.703). According to the values of Pearson correlation coefficient, the significant positive correlations were identified between Cu, Zn, Pb, Co and clay content, while the same metals are highly negative correlated with CaCO3 and fine sand contents. In case of Pb, Co, and Mn no influence of agricultural activities can be detected, wich suggestes that geogenic factors control the contents of these heavy metals. The Cu content exhibited a positive correlation with total Nitrogen, while the Cd content showed a positive significant relationship only with Km content. On the other hand, the Ni content exhibited correlation with both Pm and Km concentrations. The correlations of Cu-Nt, Cd-Km, Ni-Pm, and Ni-Km could be an index of the anthropogenic input of Cd, Cu, and Ni from the use of fertilizers.
Highlights
The quality of human life depends of the quality of the food, which is determined by the quality of the soil
The mean concentration of the heavy metals decreased in the order: Mn (594) > Zn (76) > Ni (48.7) >Cu (24)>Pb (12.7)>Co (10.2)>Cd (0.3)
The Copper content lied between 15.4 mg/kg and 36 mg/kg, the median (22 mg/kg) was higher than the median reported for Romanian agricultural soils [18] and the mean is similar with the values recorded in the West Region [19] and below of the values from North East Region [20]
Summary
The quality of human life depends of the quality of the food, which is determined by the quality of the soil. The heavy metals soil contamination was identified as one of the restrictions for the soils of Europe [1]. High levels of heavy metals can have natural or anthropic sources, but in most cases it is associated with human activity, which determined the accumulation of contaminants at high concentrations that can be a risk to the environment as well as to humans [3]. The application of the sewage sludge, manure, mineral fertilizers, fungicides, pesticides are known as sources of agricultural soil pollution with heavy metals [4,5,6,7]. Over 50% of the heavy metal input (Zn, Mo, Ni, As, Cu, Hg) in agricultural soils from France are due to livestock manure application [10]. Phosphate, nitrogen and potassium fertilizers are significant sources of Cd, Ni, Cu, and Pb [11]
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