Chuyển vị và sự thoái hóa của thuốc trừ sâu 8,1 Các mô hình ngăn Đối với tất cả các hệ thống, một con vật, một mảnh đất, một cái hồ, hoặc phong cảnh, chúng ta có thể sử dụng cùng một mô hình toán học để mô tả sự hấp thu và loại bỏ các chất hoặc ô nhiễm. Các chất có thể nhập vào hệ thống trong một sự kiện hay một tỷ lệ nhiều hơn hoặc ít hơn cố định (R - lượng chất cho mỗi đơn vị thời gian). Nó phân phối đến các khoang khác nhau trong. | chapter eight Translocation and degradation of pesticides The compartment model For all systems an animal a piece of soil a lake or a landscape we may use the same mathematical models to describe the uptake and elimination of a substance or contamination. The substance may enter the system in one event or at a more or less fixed rate R amount of substance per unit time . It distributes to different compartments in the system. A compartment is defined as a hypothetical volume of a system wherein a chemical acts homogeneously in transport and transformation Hodgson et al. 1998 . The substance disappears through excretion animals leakage soil or evaporation from soil or water or together with respiratory air or the chemical is transformed to other substances through the influence of sunlight the biotransformation enzymes of microorganisms etc. Chemical Products The disappearance rate dC dt by one process may nearly always be described by first-order or pseudo first-order kinetics . the rate is proportional with the concentration C kC or integrated C CSTART X e kt dt where C is the concentration in the compartment k is a constant and t the time. The start concentration is CSTART. An animal can often be described as 2004 by Jorgen Stenersen Intestine 0 k0i Fat Storage 2 k2i _ Blood 1 ki3 _ Liver ki2 k3i 3 Biotransformation ki0 Urine 0 a Air 0 k0i Sediment Storage 2 k2i _ Lake Water i ki3 __ Biomas 1 ki2 k3i 3 Biotransformation ki0 River 0 b Figure Simple three-compartment models for a oral administration to an animal and b a lake receiving pollution from aerial fallout. a three-compartment system or sometimes more appropriately as a four-compartment system Figure . One central compartment blood takes up a substance from the intestine at a certain rate. The substance is translocated to the liver to fat and other organs. Because the transfer back to the blood increases when the concentration in these peripheral compartments increases a dynamic equilibrium .
