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污染控制技术及原理

基金项目：科技基础性工作专项重点项目(No.2007FY110800);陕西省自然科学基金资助项目(No.2006D02);西北大学科学研究资助项目(No.Okyqdf123)

摘要：通过室内模拟试验,研究湿度对西北地区黄绵土N₂O排放的影响.结果表明:在试验温度下,随着土壤湿度增加,土壤N₂O排放量增加;但土壤孔隙含水量(WFPS)为20.67%时例外,此时黄绵土对空气中N₂O有吸附现象,即在低含水量时,黄绵土有可能是N₂O的汇.在试验设计的土壤湿度范围内,15℃条件下土壤N₂O排放的最大水分效应区间在49.18%～57.86%(WFPS)之间,20℃条件下在38.14%～49.18%(WFPS)之间,25℃、30℃和35℃时累积量湿区在20.67%～38.14%(WFPS)之间,即随着温度的升高,N₂O的最大水分效应区间提前.土壤N₂O累积排放量(y)动力学曲线符合修正的Elovich方程(P<0.01),随着湿度的增加,表观排放速率(b)增大,25℃、30℃和35℃时,N₂O初始排放量(a)也随着湿度增加而增大;15℃、20℃和25℃时,土壤湿度(20.67%～57.86%WFPS)对农田土样N₂O排放总量的作用表现为线性关系,30℃和35℃时表现为对数关系.

Abstract：Alaboratory incubation experiment was conducted to study the effect of soil moisture on N₂O flux from loessial soil in northwest China.Under the temperature conditions of this experiment,N₂O flux increased as soil moisture increased.An exception occurred at a soil moisture content of 20.67% WFPS(Water-Filled Pore Space).At this point,N₂O Absorption occurred.This indicated that loessial soil might become a N₂O sink when soil moisture is low.The maximum moisture effect on N₂O emission from soil was between 49.18%～57.86% WFPSat 15℃,ranging from 38.14% to 49.18% WFPSat 20℃,and from 20.67% to 38.14% at 25℃,30℃ and 35℃,that is,when the temperature increased,the maximum moisture effect of N₂O emission from soil shifted forward(to smaller value).Akinetic curve of cumulative N₂O flux was fit using the revised Elovich equation.The flux rate increased as soil moisture increased.Initial N₂O flux increased as soil moisture increased at 25,30 and 35℃.At 15,20 and 25℃,there was a linear correlation between soil moisture(20.67%～57.86% WFPS) and total N₂O flux from farmland,and at 30℃ and 35℃ a logarithmic correlation was observed.