露天煤矿排土场复垦土地土壤有机碳的动态变化

为探讨黄土区露天煤矿复垦土壤剖面有机碳的动态变化，以山西平朔露天煤矿排土场不同复垦阶段的耕地、林地和草地为研究对象，通过野外分层采集土样，探讨了不同复垦方向土壤有机碳含量的剖面分布特征及其与土壤pH值、全氮和w(C/N)的相关关系。结果表明：土壤有机碳的剖面分布随土壤深度和复垦方向的变化而变化，不同复垦方向土壤有机碳的垂直分布表现出一定的规律性，即随着土层深度的增加而逐渐递减；与未复垦的排土场相比，复垦2 a和18 a的耕地表层土壤有机碳含量分别增加22.73%和46.06%，复垦18 a和22 a的林地土壤有机碳含量分别增加38.86%和29.55%，复垦14 a的草地土壤有机碳含量增加30.96%，而复垦18 a的草地土壤有机碳含量变化不大；矿区3种复垦方向土壤有机碳含量整体表现为：林地>耕地>草地；复垦后的耕地土壤有机碳与全氮含量之间有显著的正相关性，相关系数R=0.642，林地和草地土壤有机碳含量与全氮之间有极显著的正相关性，相关系数R≥0.812；不同复垦方向土壤有机碳与w(C/N)的相关性都极为显著，相关系数≥0.679；耕地和林地土壤有机碳含量与pH具有明显的负相关性，相关系数分别为-0.685和-0.723，而草地土壤有机C含量与土壤pH没有明显的相关性。本研究可为黄土区露天煤矿排土场土地复垦与生态重建提供一定的借鉴和参考。

Soil Organic Carbon Dynamics of Reclaimed Soils at an Opencast Coal Mine

To reveal the dynamics of organic carbon in the soil profiles of a open-pit coal mine in loess area，and taking the farmland，woodland and grassland in different reclamation phase in Pingshuo mine dump as research targets，the profile distribution of soil organic carbon (SOC) and its relationships with soil pH，total nitrogen and w(C/N) under different reclamation directions were studied.The results indicated: the profile distribution of SOC varies with soil depth and reclamation direction; the SOC vertical distribution in different reclamation directions exhibits a certain regularity，that is，the organic carbon content decreased with the increase of soil depth; Compared with the dump not being reclaimed，the surface SOC content of farmland that reclaimed for 2 years and 18 years，increased 22.73% and 46.06% respectively，the woodland reclaimed for 18 and 22 years increased 38.86% and 29.55%,the grassland reclaimed for 14 years increased 30.96%,while grassland reclaimed for 18 years changed slightly; the sequence of the organic carbon contents in different reclamation directions from high to low is generally as follows，woodland，farmland and grassland；Significant and positive correlations were found between SOC and total nitrogen under different reclamation directions with R=0.642 in farmland,R≥0.812 in forestland and grassland;SOC are in extremely significant and positive correlation with w(C/N)，with the correlation coefficient greater than or equal to 0.679;SOC content in farmland and woodland have a significant negative relationship with pH，(with R=-0.685 in farmland,R=-0.723 in forestland)，while SOC and pH under grassland has no significant correlation.This study can provide a certain reference for land reclamation and ecological reconstruction of opencast coal mine in Loess area.