西辽河流域沙土的氨氮解吸行为研究

采用小型回填式土柱淋溶实验方法研究了西辽河流域沙土的氨氮解吸行为。结果表明,西辽河流域沙土的氨氮解吸行为符合Langmuir和Freundlich解吸等温式;沙土氨氮解吸比率Dr在0.44～0.99之间,平均为0.75,解吸迟滞性指数TⅡ在0.05～0.65之间,平均为0.29,沙土对氨氮的解吸迟滞性较强,解吸可逆性较弱。被吸附的氨氮解吸淋失的环境风险较小;沙土氨氮解吸比率Dr与土壤有机质含量、粘粒含量和粗粘粒含量呈极显著负相关,影响程度顺序为:有机质含量>粗粘粒含量>粘粒含量;解吸分配系数k和解吸迟滞性指数与土壤有机质含量分别呈极显著和显著正相关,与粘粒含量和粗粘粒含量没有相关性;草地、农田和林地结构由于土壤有机质和团聚体含量较高,氨氮解吸迟滞性较强,氨氮流失的环境风险较小,沙荒地结构氨氮流失的环境风险较大。

Desorption Behavior of Ammonium Nitrogen on sandy soil in Western Liao River Basin

Desorption behavior of ammonium nitrogen on sandy soil in Western Liao River basin was studied by a small backfilled earth-pillar of dynamic leaching experiment.Results indicate that,The behavior of ammonium nitrogen desorption conforms to the Langmuir and Freundlich isotherm.And Dr(desorption ratio) is 0.44～0.99,the average is 0.75.TⅡ(desorption hysteresis index) is 0.05～0.65,the average is 0.29.Desorption hysteresis of sandy soil is relatively strong.And reversible desorption is relatively weak.which of environment risk is low,The correlation analysis between the characteristics of ammonium nitrogen desorption and the soil physical-chemical properties was investigated and made a conclusion that,there is a highly obvious negative correlation between Dr and the soil organic matter content of the sandy soil.In addition,the ammonium nitrogen's Dr shows a obvious negative correlation to the physical clay content.And the order is: organic matter content>coarse clay content >clay content.There is a highly obvious positive correlation between TⅡ or k(desorption distribution coefficient) and soil organic matter content.In addition,the TⅡ or k shows no correlation to the coarse clay or clay content.Content of organic matter and aggregates of farmland or forestland and grassland is high,desorption hysteresis is relatively strong.The environment risk is relatively low,otherwise,the environment risk of sandy wasteland is the highest.