tailieunhanh - Phytoremediation of Contaminated Soil and Water - Chapter 9

Các mô hình cụ thể của kim loại khoan dung, sự thu hút, và Giao thông vận tải của các kim loại nặng trong Hyperaccumulating và Nonhyperaccumulating Metallophytes Khả năng phytoremediation hiệu quả của đất bị ô nhiễm kim loại nặng phụ thuộc vào sự sẵn có của giống cây trồng với tỷ lệ tích lũy và khoan dung của kim loại (s) để được chiết xuất cao. Mức độ cao của lòng khoan dung để các kim loại nặng cụ thể được biết là xảy ra trong các quần thể thực vật hoang dã từ nặng metalenriched chất nền ví. | 9 Metal-Specific Patterns of Tolerance Uptake and Transport of Heavy Metals in Hyperaccumulating and Nonhyperaccumulating Metallophytes Henk Schat Mercè Llugany and Roland Bernhard CONTENTS Introduction Plant Adaptation to Metalliferous Soils Multiple Tolerance and Cotolerance Mechanisms of Tolerance Hyperaccumulation Metal Uptake Transport and Tolerance Correlated Patterns of Metal Specificity Conclusions References INTRODUCTION The possibility of effective phytoremediation of heavy metal-contaminated soil depends on the availability of plant varieties with high rates of accumulation and tolerance of the metal s to be extracted. High levels of tolerance to specific heavy metals are known to occur in wildtype plant populations from heavy metal-enriched substrates such as ore outcrops or mine-waste deposits. A minority of the species concerned the so-called hyperaccumulators exhibit extremely high rates of foliar metal accumulation. It may be argued that hyperaccumulators are insufficiently productive in terms of harvestable above-ground biomass to be useful in phytoremediation although this argument does not seem to apply to all of them. Plant species from metalliferous soil metallophytes possess desirable properties Copyright 2000 by Taylor Francis which might be transferable to more productive species by means of genetic engineering or interspecific crossing. Moreover hyperaccumulating and nonhyperaccumulating metallophytes exhibit highly variable patterns of metal specificity with regard to uptake root-to-shoot transport and tolerance both inter- and intraspecif-ically. This variation which could be useful in phytoremediation has not been fully explored and the underlying genetic and physiological mechanisms are far from understood. Further studies may be expected to provide insights with possible implications for phytoremediation technology. This chapter summarizes the present knowledge of the mechanisms and genetics of heavy metal tolerance in .