Copper content of soils and river sediments in a winegrowing area, and its distribution among soil or sediment components.

摘要

This paper concerns copper levels in the components of soils and river sediments in a river basin partially devoted to vineyards that are regularly treated with copper-bearing grapevine fungicides. Copper concentrations were determined in 26 soil samples, 20 river sediment samples and 71 river water samples taken in a small basin with steep slopes suffering significant erosion. Mean total Cu concentration was 31 mg kg-1 in woodland soils, 30 mg kg-1 in pasture soils, and eight times higher, 246 mg kg-1 (range 157-434 mg kg-1), in productive vineyard soils. Total copper concentration in river sediments ranged from 18 to 209 mg kg-1 depending on the proportion of land under vineyard in the sub-basin drained via the sampling point (r=0.915, p<0.05). Soils differed relatively little as regards the distribution of Cu among various fractions; in particular, about 50% of total copper content was generally bound to soil organic matter. The distribution of Cu in sediments was more heterogeneous: sandy sediments had copper distributions similar to those observed in soils, but in silty sediments with large inorganic colloids fractions it was these amorphous colloids that bound the largest proportion of copper (mean 31.5%). The absence of significant differences among water-soluble Cu concentrations at the various water-sampling points suggests that winegrowing does not increase water-soluble Cu levels in the river under normal circumstances.