Adsorption/desorption mechanism of ammonia nitrogen in aerated zone of loess soil
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DOI:10.7606/j.issn.1000-7601.2021.02.24
Key Words: aeration zone of loess  ammonia nitrogen  adsorption-desorption  influencing factors
Author NameAffiliation
DUAN Lei School of Water Resources and EnvironmentChang’an University Xi’an, Shaanxi 710054, China
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Xi’an, Shaanxi 710054, China 
LV Jiajia School of Water Resources and EnvironmentChang’an University Xi’an, Shaanxi 710054, China
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Xi’an, Shaanxi 710054, China 
SUN Yaqiao School of Water Resources and EnvironmentChang’an University Xi’an, Shaanxi 710054, China
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Xi’an, Shaanxi 710054, China 
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Abstract:
      This paper took loess in the Guanzhong Basin as the research object, combined field sampling, indoor simulation experiments, and statistical analysis of data, and systematically analyzed the change trends of typical material components at different depths in the aeration zone of loess (organic matter content, CaCO3, and oxides) and the adsorption/desorption characteristics of ammonia nitrogen (N). On this basis, the article selects loess (L1) and paleosol (S5) as examples to reveal the influence mechanism of the typical material components in the aeration zone of loess on the adsorption/desorption behavior of ammonia N. The study showed that the amplitude of adsorption (300~1 100 ug·g-1) in the aeration zone of loess was larger than the amplitude of desorption (100~380 ug·g-1), and the adsorption capacity decreased with increasing depth, and the desorption capacity fluctuated greatly in the shallow (-20 m) and was stable in the deep layers. For soils at different depths, the adsorption/desorption capacity of adjacent paleosols for ammonia N is basically greater than that of loess soils. On the whole, the average desorption rate of loess was 8.65% higher than that of paleosols. The most significant influence on the adsorption/desorption behavior of ammonia N by the constituents of the loess zone was organic matter and CaCO3. Organic matter and CaCO3 had a positive correlation with the adsorption/desorption of ammonia N. In addition, oxides had little effect on the adsorption/desorption behavior of ammonia N. Therefore, the changes in the content of typical substances in the aeration zone of loess at different depths were the main factors that caused the difference in ammonia N adsorption/desorption. The research further indicated the influence mechanism of ammonia N adsorption/desorption in the aeration zone of loess, and provided the scientific and technological support for agricultural fertilization and soil pollution control on the Loess Plateau.