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Một vài thập kỷ trước, sự quan tâm về các chất dinh dưỡng kim loại là rất cần thiết cho sự phát triển của thực vật tập trung về cơ bản điều tra các yếu tố gây thiếu hụt cho các nhà máy (Thorne, 1959; Brown, 1961). Mục tiêu chính là huy động của kim loại đánh dấu để rễ cây. Ngày nay, sự quan tâm đã chuyển sang hướng ngược lại, tức là, để loại bỏ các kim loại dư thừa hoặc chuyển cho giai đoạn bất động. Đó là bởi vì kim loại đánh dấu trở nên quan trọng môi trường chất gây. | 6__ Soil pH Effect on the Distribution of Heavy Metals Among Soil Fractions C.D. Tsadilas CONTENTS 6.1 Introduction.107 6.2 Materials and Methods.109 6.2.1 Soils and Measurements.109 6.2.2 Soil pH Adjustment.109 6.2.3 Trace Metal Fractionation.109 6.2.4 Statistical Analysis.110 6.3 Results and Discussion .110 6.3.1 Soil Characteristics .110 6.3.2 DTPA-Extractable Metals .110 6.3.3 Metal Fractions . 111 6.3.4 Lead Fractions. 111 6.3.5 Nickel Fractions.112 6.3.6 Zinc Fractions.112 6.3.7 Copper Fractions.113 6.3.8 Manganese Fractions.113 6.3.9 Relationship between DTPA-Extractable and Metal Fractions.113 6.4 Conclusions .116 6.5 Summary .118 References .118 6.1 Introduction Some decades ago the interest about the metal nutrients that are essential for plant growth focused basically on the investigation of factors causing deficiency to the plants Thorne 1959 Brown 1961 . The main goal was the mobilization of trace metals to plant roots. Nowadays the interest has shifted into the opposite direction i.e. to removing excess metals or transferring them to immobile phases. That is because trace metals became important environmental contaminants seriously affecting the whole ecosystem. Practices associated with mining and smelting of ores secondary smelting of scrap metals and industrial and municipal wastes caused a high accumulation of potentially toxic metals to soils that can enter the food chain and affect human health. Metal sources related especially to the food 107 2001 by CRC Press LLC 108 Environmental Restoration of Metals-Contaminated Soils chain are municipal sewage sludge composts swine and poultry manure industrial wastes coal fly ash and P fertilizers Adriano et al. 1997 . For mitigation of the consequences caused by the use of metal containing materials the responsible authorities imposed restrictions in their use. The U.S. Environmental Protection Agency U.S. EPA 1993 as well as the European Union CEC 1986 .