tailieunhanh - ENVIRONMENTAL RESTORATION of METALSCONTAMINATED SOILS - CHAPTER 4

Số phận và sinh khả dụng của kim loại trong đất bị chi phối bởi nhiều quy trình về môi trường. Nếu không xem xét các phản ứng vận chuyển và vùng rễ, các quá trình ảnh hưởng đến dấu vết kim loại hấp thụ bởi một nhà máy được mô tả trong hình . Tất cả các cây kim loại trong đất qua nước lỗ rỗng, do đó, các phân vùng của kim loại từ dung dịch đất và các chất rắn là yếu tố chính xác định sinh khả dụng kim loại. Ái lực mạnh giữ cho vững chắc của đất bề mặt. | 4_ Determinants of Metal Retention to and Release from Soils Yujun Yin Suen-Zone Lee Sun-Jae You and Herbert E. Allen CONTENTS Experimental Results and Sorption of Metals to Sorption of Sorption of Soil Sorption Metal Desorption from Introduction Fate and bioavailability of metals in soils are governed by many environmental processes. Without consideration of transport and rhizosphere reactions the processes influencing a trace metal uptake by a plant are depicted in Figure . All plants take up metals in soils via pore water therefore the partitioning of metals between soil solution and solids is the primary factor determining metal bioavailability. Strong retention affinities for soil solid surfaces would reduce the risk of a metal species to the ecosystem whereas poor retention by soil particles would result in more metal present in soil solution for uptake by soil organisms. Not all the metal in the solution phase is bioavailable. Both aqueous inorganic ligands and organic ligands including natural dissolved organic matter and anthropogenic ligands compete with binding sites on the organism for the metal. The soluble major cations such as Ca2 and protons can also compete with the metal of interest for the available binding sites on the organism. In addition the biotic processes also affect uptake. The combined effects of all of these processes determine biological uptake of metals. Clearly to determine if a metal contained in the soil at a specific location has potential hazard to the environment both equilibrium and kinetic aspects of these processes have to be understood. This chapter focuses on equilibrium or pseudo-equilibrium as soils may not be at equilibrium aspects of metal retention and release processes in soils. 77 2001 by CRC Press .