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可溶性有机碳在土壤剖面淋溶过程中的分馏

熊丽1,2,杨玉盛1,2,万菁娟1,2,司友涛1,2**   

  1. (1湿润亚热带山地生态国家重点实验室培育基地, 福州 350007; 2福建师范大学地理科学学院, 福州 350007)
  • 出版日期:2015-05-18 发布日期:2015-05-18

Fractionation of dissolved organic carbon along soil profiles during the leaching process.

XIONG Li1,2, YANG Yu-sheng1,2, WAN Jing-juan1,2, SI You-tao1,2   

  1. (1Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology, Fuzhou 350007, China; 2School of Geographical Science, Fujian Normal University, Fuzhou 350007, China)
  • Online:2015-05-18 Published:2015-05-18

摘要: 选取中亚热带两种不同类型土壤为研究对象,采集0~10、10~20、20~40、40~60、60~80、80~100 cm土层土壤样品,提取米槠新近凋落物的可溶性有机碳(DOC)溶液为初始DOC,研究其在土样中淋溶时的分馏现象和截留特征.结果表明:初始DOC在土柱中淋溶时,其浓度随深度增加呈逐层下降的趋势,而且化学结构更为简单,被土壤截留的DOC中主要是疏水性组分,但随着土层深度增加,亲水性DOC的截留量呈上升趋势;红外光谱显示含有芳环的疏水性物质最易被吸附,而烷烃和简单的碳水化合物则最有可能随土壤溶液进入下层土壤;由于到达下层土壤的DOC中易被吸附组分含量的减少,限制了其吸附能力的发挥,因此主要的吸附过程发生在40 cm以上土层,表明DOC本身的化学性质比土壤性质更能影响其吸附行为;不同类型土壤的截留量具有显著差异,这与土壤黏粒和铁铝氧化物的含量呈显著正相关.

Abstract: Two distinct soil types in midsubtropical China were selected for soil sampling at the depth of 0-10, 10-20, 20-40, 40-60, 60-80, 80-100 cm for soil cores preparation. Dissolved organic carbon (DOC) extracted from recently fallen litters of Castanopsis carlesii with ultrapure water was leached through such soil cores to investigate the fractionation and retention pattern when migrating along the soil layers. The results showed the leachates out of deeper soil cores had lower concentrations and were chemically simpler, the hydrophobic pools contributed to the majority of the retention, but the proportion of retained hydrophilic materials gradually increased with the increasing soil depth. The infrared spectrum suggested that the hydrophobic materials containing aromatic rings could be easily absorbed by soils, but alkanes and simple carbohydrates would transport into subsoils with soil solution. Proportional decrease in the highly sorptive DOC restricted C sorption by subsoils, and thus the adsorption occurred mainly in 0-40 cm soil layers, suggesting that the chemical nature of DOC had a greater influence on sorption capacity of the soils than soil physicochemical properties. The retention amounts of DOC by different soil types differed significantly, which were significantly positively correlated with the contents of clay, iron and aluminum oxides.