ZEA MAYS(L.) IN AREAS WITH DIFFERENT ANTHROPIC POLLUTION SOURCES: RELATIONS BETWEEN TOXIC ELEMENT CONTENTS IN SOILS AND VEGETABLE TISSUES

摘要

The aim of this work is to evaluate the pollution level of different agricultural soils cropped with Zea mays (L.) in the area surrounding Rome (Italy), and its effects on toxic element content in vegetable tissues. In 10 farms exposed to different anthropic pollution sources, the element bio-availability in soil and the translocation of toxic elements from the roots to the plant epigean part have been studied. The relationships between each plant and its rhizosphere have been directly evaluated by sampling the individual(plant)/rhizosphere specimens. The soils have been characterized for the main physical-chemical properties and submitted to selective extraction procedures with EDTA and simulated rainwater, for obtaining information about the mobile (or mobilizable) fractions of toxic elements. Both the element total content and the extractable fractions have been determined. Concerning the maize plants, the element contents have been determined in each vegetable tissue apart: roots, epigean and caryopsises (edible). Measurement of the element contents has been carried out by ICP-AES and ET-AAS, after acid digestion by a microwave system. This work supplies a conspicuous experimental data set, that could be used to evaluate the plant uptake of toxic elements and the element distribution in the different vegetable tissues. The results let especially estimate the element mobility and bioavailability considering each single plant/rhizosphere specimen. The experimental results permit to highlight interesting inter-elemental relationships and some observations on vegetable/soil extractable contents ratio. Some considerations about the effectiveness of the two extractants used are also pointed out.