红壤侵蚀退化地土壤对不同来源可溶性有机碳的吸附特征

选取南方典型红壤侵蚀退化地恢复后的马尾松林为研究对象,通过在室内模拟芒萁(Dicranopteris dichotoma)和马尾松(Pinus massoniana)的鲜叶与凋落叶的浸提液在侵蚀退化地原状土柱的淋溶过程,分析了植被恢复过程中马尾松林土壤对不同来源可溶性有机碳(DOC)吸附特征及影响因素。结果表明:(1)红壤侵蚀退化地对不同来源DOC的吸附作用具有明显差异,来自马尾松鲜叶的DOC平均截留量最大为2.39mg/kg,来自芒萁鲜叶的DOC平均截留量最小为1.67mg/kg,说明马尾松鲜叶的DOC更易被表层土壤吸附,芒萁鲜叶的DOC更易进入深层土壤,不同来源DOC组成和性质的差异是其主要原因。(2)随着退化地的植被恢复,土壤渗滤液的DOC浓度增加,土壤截留DOC能力下降。土壤DOC截留量与粉粒和土壤pH呈正相关,与土壤DOC含量、土壤有机碳含量和砂粒呈负相关,其中土壤有机碳含量可以解释DOC截留量变化的51.4%,是影响土壤DOC截留能力的关键因素。(3)光谱特征表明芳香类化合物、腐殖类物质易被土壤吸附,吸附能力更强的物质可以解吸土壤中亲水性腐殖类物质。淋溶后DOC光谱特征的变化由不同来源DOC的化学组成和土壤有机碳的性质共同决定。红壤侵蚀退化地对不同植物来源的DOC吸附作用特征主要受DOC和土壤SOC性质的共同调控,对进一步认识退化红壤的固碳机制具有重要参考价值。

Adsorption Characteristics of Soil to Dissolved Organic Carbon Derived from Different Sources in Eroded Degraded Red Soil

Pinus massoniana forest after the restoration of eroded degraded land in the typical red soil of southern China was selected as the research object. Dissolved organic carbon (DOC) extracted from the fresh leaves and the leaf litter of P. massoniana and Dicranopteris dichotoma was leached through such soil cores of eroded degraded land in indoor simulation, and the adsorption characteristics and influencing factors of DOC from different sources in P. massoniana forest during vegetation restoration was analyzed. The results showed: (1) The adsorption of red soil eroded degraded land on DOC from different sources had obvious difference, the maximum of DOC average interception from the fresh leaves of P. massoniana was 2.39 mg/kg, the minimum of DOC average interception from the fresh leaves of D. dichotoma was 1.67 mg/kg. DOC from the fresh leaves of P. massoniana was more susceptible to surface soil adsorption, while DOC from the fresh leaves of D. dichotoma was easy to enter the deep soil, different sources of DOC composition and properties was the main reason for this difference. (2) With the increase of vegetation restoration years, the DOC concentration of soil leachate increased, and the soil interception ability of DOC decreased. DOC interception was positively correlated with the content of silt and soil pH, negatively correlated dissolved organic carbon and soil organic carbon and the content of sand. Soil organic carbon content could explain 51.4% of the change of DOC interception, and is the key factor affecting the ability of soil DOC interception. (3) The spectral characteristics showed that aromatic compounds and humic substances were easily adsorbed by soil, and the substances with stronger adsorption capacity could desorb hydrophilic humic substances in soil. The change of DOC spectral characteristics after leaching was determined by the chemical composition of DOC from different sources and the properties of soil organic carbon. The adsorption characteristics of eroded degraded red soil on DOC from different plant sources was mainly controlled by DOC and soil SOC properties, and this provided important reference value for further understanding the mechanism of carbon sequestration in degraded red soil.