Study On The Transfer Characteristics Of Copper From Soils To Major Vegetables In Fujian Province

The availability of soil copper, the factors influencing the Cu availability, and the transfer characteristics of Cu from soil to the edible parts of various vegetables were studied based on an investigation carried out over 8 counties in Fujian province. The main results were as follows:1. The total Cu contents of the surface soils (≤15cm) ranged between 1.68 and 184.13mg.kg^-1 with an average of 53.28mg.kg^-1. The total Cu concentrations of 52.1% of the soils studied were lower than the Cu limits for agricultural land in the China soil environmental quality standard (pH<6.5, farmland<50mg.kg^-1), implying that the soils in these regions have more or less been polluted by copper.2. DTPA-CaCl₂-TEA (pH7.3) was chosen for extracting the available Cu of the soils because it was found to be the best for available Cu extraction for acid soils than the others, HC1 and EDTA. However, the extraction conditions were modified according to our preliminary study as follows liquid:soil= 10:1, shaking time=120 minutes, shaking velocity=210rpm. The available Cu of the soils varied from 0.50 to 33.36 mg.kg^-1 with a mean of 6.39mg.kg^-1. The available degree of the soil Cu (the ratio of the available Cu concentration to the total Cu concentration) varied from 1.5% to 68.9% with a mean of 12.9%.3. The Cu contents (fresh weight basis) of various kinds of vegetables ranged between 0.09 and 3.31 mg.kg^-1. The Cu concentrations of all the vegetables were lower than the limit of the China food hygiene standard, indicating that the vegetables produced in these regions were quite safe for cosumption.4. The Cu concentrations in the edible parts of most of the vegetables species did not significantly correlated with both the soil total and available Cu, which may be attributed to the effects of the factors other than the soil Cu status, such as gowth characteristics, fertilization, agricultural managements and climate. Soil-to-plant transfer factors of Cu (total Cu based or available Cu based) decreased with the increase of soil total Cu and available Cu, most of which can be best described by exponential equation (y=ax^b) .5. According to the ranges of the total and available Cu of the soils used in this study, the representative Cu accumulation index of each vegetable were estimated based on the regression equations between the transfer factors and the soil total Cu or available Cu at the concentrations of 20mg.kg^-1(total Cu) and 5mg.kg^-1(available Cu), respectively. All the vegetable species studied were grouped into three categaries...