氚水在模拟水稻－水－土壤生态系统中的行为

采用模拟污染物的同位素示踪技术研究HTO(流水)在水稻-水-土壤模拟生态系统中的迁移、消长行为，并应用三库室开系统模型和非线性回归方法确定了水稻、水和土壤分室的拟合方程．结果表明，田表水中的HTO不仅在系统各分室间转移和分配，而且迅速向系统外散逸；HTO中的流以自由水氚和结合态流形式存在于水稻中，以吸湿性水流和结晶水氚存在于土壤，其中自由水氚(或吸湿性水氚)的比活度大于结合态流(或结晶水氚)；水稻植株和土壤中HTO比活度随时间增加至最大值后又趋于下降，而结合态氚则呈缓慢增加；水稻茎秆中的总氚比活度高于其它各部位，而后逐渐趋于动态平衡．对实验数据进行回归分析得：田表水、土壤和水稻植株中的总氚比活度分别为Cw(t)=32.19c^-0.0353t 99.94c^-0.330t、Cs(t)=20.42(e^-0.0353t-e^-0.330t)和Cr(t)=38.49c^-0.0353t-10.13e^-0.330t-28.36c^-2.5744t。方差分析结果表明，各回归方程较好地反映了HTO在水稻—水—土壤生态系统中的行为．

Behavior of HTO in simulated rice-water-soil ecosystem

The behavior of transportation,accumulation and disappearance of HTO (tritium water) in a simulated rice water soil ecosystem was studied by using isotope tracer techniques for simulated pollutants, and the fitting equation was confirmed by application of the open three compartment system model and nonlinear regression method. The results showed that HTO in water was not only transferred to other compartments in the ecosystem, but also vaporized into atmosphere rapidly. Both free water tritium and bound tritium were found in the rice, and tritium of hygroscopic and crystalline water was consisted in the soil. The specific activity of free water tritium (or tritium of hygroscopic water) was stronger than that of bound tritium (or tritium of crystalline water). The specific activity of total tritium reduced after reaching the maximum in the rice and soil, and the bound tritium increased slowly. The specific activity of total tritium in stem was the strongest in the rice, and reached equipoise each other in the later stage gradually. The regression equations of accumulation and disappearance for the specific activity of total tritium in the water, soil and rice were given by analyzing the obtained data with exponential regression method. The analysis results of variance showed that each regression equation could describe the behavior of accumulation and disappearance of HTO in the rice water soil ecosystems preferably.