济宁煤矿区采煤塌陷对土壤有机碳的影响

Effects of Coal Mining Subsidence on Soil Organic Carbon in Jining Coal Mining Area

采煤造成地表塌陷,原地貌发生大的变化,土壤受到严重扰动,致使土壤养分转化和迁移发生较大的空间变异,而土壤有机碳的变化是表征土壤养分的关键因子。土地塌陷对土壤有机碳的影响逐渐成为复垦土壤质量的研究热点问题。本研究选择济宁兖州煤矿区典型塌陷区,采集不同坡位和不同深度的土壤样品,分析土壤有机碳在坡面和垂直剖面上的分布特征及影响因素。结果表明:(1)在坡面上,土壤有机碳呈现出从坡顶到积水边缘迁移,先降低再升高,在塌陷中心富集的变化趋势,采煤塌陷对坡中和坡底部位的土壤有机碳含量影响差异显著(P<0.05);(2)在垂直剖面上,土壤有机碳含量随着土壤剖面层次的加深而降低,有机碳含量主要集中在0~20 cm土层,占整个土层(0~60 cm)的65.9%,显著高于20 cm以下各层次的有机碳含量(P<0.05);(3)土壤的不同性质空间变异程度大小排序大致为:有机碳>热导率>含水量>容重>pH值;(4)土壤有机碳与容重、含水量、pH值、热导率均呈负相关关系,其中与含水量的相关性达到显著水平,相关系数为-0.493*(P<0.05),与容重和pH值达到极显著相关,相关系数分别为-0.699**、-0.684**(P<0.01),与热导率的相关性不显著。土地塌陷产生的地面坡度已经引起土壤有机碳的流失,土壤肥力下降,土地生产力也随之下降。

The coal mining causes surface subsidence. The original landform changes a lot,and the soil is seriously disturbed,which resulting in soil nutrient transformation and migration at large spatial variation.The variation of soil organic carbon is the key representation factor of soil nutrient. The study on the impacts of land subsidence on soil organic carbon has gradually become a hot issue of reclamation soil quality. In this study,a typical subsidence area in Yanzhou coal mining area of Jining was selected to collect soil samples at different slope positions and depths,and the distribution characteristics and influencing factors of soil organic carbon on the slope and vertical profiles were analyzed. The results were as follows.( 1) In the slope direction,soil organic carbon showed decreasing at first and then increasing from the top to the edge of water transfer,and enriched at the collapse center. The effects of mining subsidence on soil organic carbon content on the middle and base of slope had significant differences( P < 0. 05).( 2) In the vertical section,the content of soil organic carbon decreased with the increase of depth in soil profile. The content of organic carbon was mainly concentrated in the 0 ~ 20-cm soil layer,accounting for 65. 9% of the whole soil( 0 ~ 60 cm),andit was significantly higher than those in the soil layer below 20 cm( P < 0. 05).( 3) The spatial variability degree of different soil properties are ranked as follows: organic carbon > thermal conductivity > water content >bulk density > pH value.( 4) Soil organic carbon were negatively related with soil bulk density,water content,pH value and thermal conductivity,and the correlation with water content reached a significant level with the correlation coefficient as-0. 493*( P < 0. 05); the correlations with the bulk density and pH value reached very significant levels with the correlation coefficients as-0. 699**and-0. 684**( P < 0. 01); and the correlation with thermal conductivity did not reach the significant level. The land slope caused by land subsidence had already caused the loss of soil organic carbon,which further resulting in decline of soil fertility and land productivity.