煤矸石充填重构土壤剖面温度变化对覆土厚度的响应

摘要

为探究不同覆土厚度煤矸石充填重构土壤剖面温度变化及其对表层土壤微生物量碳(MBC)含量和土壤呼吸的影响,根据覆土厚度将研究区分为A(15 ～40 cm),B(40 ～ 60cm),C(60 ～ 80 cm)和D(80～100 cm)4类监测区,分别测定重构土壤0～120 cm土壤层温度和表层土壤呼吸速率,并采集表层土壤测定其MBC的含量.结果表明:监测区表层土壤(5 cm)日最高温度和温度变幅均呈A＞B＞D＞C,监测区A和B年均温度要比C和D高出1℃左右.矸石层的存在会影响表层0～20 cm土壤温度的日变幅,并且随着覆土厚度的增加,表层土壤温度日变幅逐渐减小.当覆土厚度大于80 cm时,土壤层的温度变化几乎不受矸石层的影响.随着太阳辐射的增加,矸石层对土壤层温度的影响也会增强,并且随着覆土厚度的增加,矸石层对土壤层温度的影响会逐渐削弱.Tc值(矸石层对表层土壤的温度影响系数)能够准确地定量分析矸石层对土壤层温度的影响并估算重构土壤的覆土厚度.重构土壤表层土壤MBC含量与温度无显著相关性,覆土厚度过薄或过厚均不利于MBC的累积,当覆土厚度在60～ 80 cm时最有利于表层土壤MBC的累积,其年均MBC含量为83.46 mg/kg.重构土壤呼吸速率与土壤温度呈显著正相关,但不同覆土厚度重构土壤呼吸速率的差异主要是由矸石层引起,并且矸石层对重构土壤的影响随着覆土厚度的增加逐渐减小.%The temperature of reconstruction soil with 0-120 cm thickness,soil respiration rate and microbial biomass carbon (MBC) content were determined.The study area is divided into four kinds of monitoring areas for A (15-40 cm),B (40-60 cm),C (60-80 cm),and D (80-100 cm) according to topsoil in order to analyze the reconstruction soil filling with coal gangue profile temperature change with different topsoil thickness and its influences on MBC content and soil respiration.The results show that the highest temperature and temperature change range of surface soil (5 cm) of the monitoring area is A ＞ B ＞ D＞C.The annual average temperature of the monitoring area of A and B are higher than C and D for 1 ℃.The existence of coal gangue will affect the temperature change of soil with 0-20 cm thickness,and the surface soil temperature amplitude decreases with the increase of topsoil thickness.When the topsoil thickness is greater than 80 cm,the temperature change of the soil layer is almost not affected by coal gangue.The influence of coal gangue on surface temperature increases with the solar radiation increases and the soil layer temperature decreases with topsoil increases.The value of Tc (the temperature influence coefficient of coal gangue on surface soil) can accurately analyze the influence of coal gangue on soil layer temperature and calculate topsoil thickness.There is no obvious correlation between the MBC content and soil temperature.The too thick or too thin topsoil is not conducive to the MBC accumulation,but the topsoil thickness in 60-80 cm is the most conducive to the MBC accumulation and its annual average content is 83.46 mg/kg.Soil respiration rate of reconstruction soil is correlated to soil temperature,but the differences between reconstruction soil with different topsoil thicknesses are mainly affected by coal gangue.With the topsoil thickness increasing,the effects of coal gangue layer on reconstructed soil are reducing.Thus,the respiration rate of reconstructed soil is gradually enhancing with topsoil thickness increasing.