玉米-土壤和大豆-土壤体系中95Zr的消长动态

采用模拟污染物的同位素示踪技术进行了⁹⁵zr在2种作物-土壤体系中的消长动态研究,并应用库室模型和非线性回归方法确定了各体系的拟合方程.结果显示:①玉米和大豆从土壤中吸收的⁹⁵Zr主要集中在根部,且根部中的⁹⁵Zr比活度随时间呈缓慢增加,并在经历一段时间后逐渐趋于动态平衡;其余各部位的比活度较低,较大部分接近于本底水平,表明⁹⁵Zr被玉米和大豆根系吸收后不易在其体内迁移、输运;②喷施进入土壤中的⁹⁵Zr主要滞留在表层(0～8cm)土壤中,其量占总量的97.5%以上,表明⁹⁵Zr被表层土壤吸附,不易随水流向下迁移;③对实验数据进行回归分析,得玉米和大豆植株中⁹⁵Zr比活度的消长动态拟合方程为C_m(t)=3.2067(1-e^01582t)和C_b(t)=3.0925(1-e^-0.1363t),经方差分析,表明回归方程较好地反应了⁹⁵Zr在玉米-土壤和大豆-土壤体系中的消K动态.

Dynamics of Accumulation and Disappearance of Zirconium-95 in the Maize/Soil and Soybean/Soil Ecosystem

The dynamics of accumulation and disappearance of 95Zr in two kinds crop-soil ecosystem was studied by using isotope-tracer techniques for simulated pollutants, and the fitting equation was confirmed by application of the closed tow-compartment model and nonlinear regression method. The results showed: 1. The Zirconium-95 absorbed from soil main retention in root of the maize and soybean, and the specific activity of 95Zr in root increased with time slowly, then tended dynamics balance gradually after a period of time. The specific activity of rest parts was lower, and biggish parts were background activity level, which indicated that the 95Zr absorbed by roots was difficult of transference and transportation in the maize and soybean. 2. The 95Zr in soil main retention in surface layer soil(0-8 cm), and the rate of it's activity and total activity > 97.5%, which indicated that the 95Zr absorbed by surface soil could not readily move downwards with percolating water. 3. The regression equation of accumulation and disappearance of 95Zr in the maize and soybean were Cm(t) = 3.2067(1 - e-0.1582t) and Cb(t) = 3.0925(1- e -0.1363t) by analyzing the experiment data with exponential regression method. The results of squared deviations analyzing indicated that each regression equation could describe the dynamics of accumulation and disappearance of 95Zr in the maize-soil and soybean-soil ecosystems preferably.