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石冠腐殖土在喀斯特地区广泛分布,具有维系喀斯特生态系统植物多样性、截留沉降养分和水分等重要的生态功能。本文以云南石林为例,选择典型石漠化生态系统、人工林生态系统和次生林生态系统,实地取集各类小生境的石冠腐殖土样,并进行NH_4~+-N吸附实验,探究石冠腐殖土对NH_4~+-N的吸附动力学和等温吸附特征。结果表明:石漠化生态系统、人工林生态系统和次生林生态系统每平方米岩石投影面积的石冠腐殖土分别为40.45±25.38g、38.89±9.92g和397.66±142.71g;石冠腐殖土对NH_4~+-N的吸附动力学遵循准二级反应动力学方程,2min内能完成吸附量的65%~75%,吸附平衡时间约为20min;腐殖土对氨氮的吸附量随加入NH_4~+-N浓度的升高而增加,吸附等温线符合Boxlucas1模型,依据此模型计算出的石漠化生态系统石冠腐殖土的吸附性能最大,最大吸附量约7.79g/kg,人工林次之,为5.29g/kg,次生林的吸附性能最小,吸附量仅为4.73g/kg,腐殖土对氨氮的截留率为20%~50%。
The crown humus soil is widely distributed in the karst area and has the important ecological functions of maintaining the plant diversity of the karst ecosystem and intercepting sediment nutrients and water. Taking Shilin in Yunnan Province as an example, this paper selected typical rocky desertification ecosystem, plantation ecosystem and secondary forest ecosystem. The samples were collected from various types of microculture habitats and NH_4 ~ + -N adsorption experiments were conducted. Adsorption Kinetics and Isothermal Adsorption Characteristics of NH_4 ~ + -N by Crown Corbion. The results showed that the stone crown humus per square meter of rock projection area of rocky desertification ecosystem, plantation ecosystem and secondary forest ecosystem were 40.45 ± 25.38g, 38.89 ± 9.92g and 397.66 ± 142.71g respectively; The adsorption kinetics of soil NH_4 ~ + -N followed quasi-second-order reaction kinetics equation, which could finish 65% -75% of the adsorption amount within 2min and the adsorption equilibrium time was about 20min. The adsorption amount of ammonia nitrogen on humus soil NH_4 ~ + -N concentration increased, and the adsorption isotherms accord with the Boxlucas1 model. According to this model, the adsorption capacity of the crown-covered humus soil in the rocky desertification ecosystem is the largest, the maximum adsorption capacity is about 7.79g / kg, Lin secondary, 5.29g / kg, secondary forest minimum adsorption capacity, the adsorption capacity of only 4.73g / kg, humus soil ammonia nitrogen rejection of 20% to 50%.