Uptake of lead by vegetables grown in contaminated soil
Sommaire de l'article
Potatoes, carrots, beetroots, lettuce and rhubarb were cultivated on soil, that had been severely lead-contaminated by industrial activities at three different locations in Sweden. The vegetables were grown in the gardens of people living in the district, or in some other way making use of the land in the contaminated areas. In some cases, the vegetables were grown in a greenhouse in pots filled with soil from the contaminated sites. Samples of vegetables and soil were collected simultaneously. The vegetables were dry ashed at 450 degrees C and analysed for lead using graphite furnace atomic absorption spectrophotometry with background correction. Certified reference materials were analysed simultaneously with the samples. Soils were extracted according to two methods based on extraction with 2 M HNO3 and NH4OAc, respectively. Lead was determined as above. The pH was determined in a filtered mixture of soil and water (1:2) and recalculated to H+. The results for both vegetables and soils spanned over quite a wide range, for vegetables between < 0.004 and 2.7 mg/kg fresh weight. In the soils, the results ranged from 9.6 to 4400 mg/kg dry weight for the HNO3 fraction, and from 2.3 to 478 mg/kg for the NH4OAc fraction. Regression analysis showed a significant positive correlation (p<0.05) between lead levels in all the vegetables and lead levels in both of the soil fractions together with H+.