风化煤对晋陕蒙矿区排土场新构土体土壤呼吸的影响

Effect of weathered coal on soil respiration of reconstructed soils on mining area's earth disposal sites in Shanxi-Shaanxi-Inner Monglia adjacent area

为探讨风化煤添加对晋陕蒙矿区排土场沙黄土及砒砂岩掺混沙黄土等新构土体土壤呼吸特征的影响,该文设置沙黄土、沙黄土+风化煤、沙黄土+风化煤+砒砂岩掺混、沙黄土+砒砂岩掺混的4种新构土体,采用Li-8100土壤呼吸测量系统测定田间土壤呼吸,分析了不同土体重构方式土壤呼吸特征及其与土壤水热因子的相互关系。结果表明:1)风化煤添加后沙黄土+砒砂岩土体与沙黄土土体土壤呼吸速率分别提高了35.2%(P<0.05)和17.1%,沙黄土土壤呼吸日变化为单峰曲线,风化煤添加后日变化呈双峰曲线。2)各土体土壤呼吸与土壤温度均呈极显著的指数函数关系,vant’Huff模型可用来模拟各土体土壤呼吸对土壤温度的响应。3)监测期内土壤含水率整体较高,土壤呼吸与土壤水分具有一定的线性关系,但不显著。土壤呼吸与土壤温度、水分多元线性分析结果也表明,监测期内新构土体土壤呼吸与土壤温度显著相关,与土壤水分相关性不显著,土壤温度可以解释土壤呼吸的大部分变异。综合研究结果表明风化煤促进了新构土体土壤呼吸,提高了碳释放速率,同时也改变了土壤呼吸日变化格局。研究阐明了添加风化煤对矿区新构土体碳通量释放的影响,对评估风化煤添加土体优缺点,估算未来局部碳变化具有积极意义。

Jin-Shan-Meng adjacent region is an important coal energy base in China, and also the most fragile ecological region. In recent years, the ecological system and landform have been destructed severely and widely because of opencast coal mining. So, how to improve the reconstructed soil rapidly and effectively on the earth disposal sites formed during coal mining becomes an important scientific problem for land reclamation and ecosystem restoration. Weathered coal, as a common organic material with an abundance of humus acid and oxygen-containing functional group, is probably an effective soil amendment material. However, adding weathered coal into soil in large scale might change the regional soil carbon cycling. To clarify the feasibility of weathered coal as an improvement material of soil quality and investigate the effect of weathered coal on soil respiration of the reconstructed soils on the earth disposal sites in this region, the soil respiration characteristics and the influence of soil temperature and soil moisture were studied. Two types of the reconstructed soils i.e. the local sandy loess (sandy loam) and the sandy loess mixed with soft rock were adopted, and the 2 components of latter soil were mixed at a ratio of 7:3 in weight; the thickness of soil layer covered was 50 cm. The 4 treatments with 3 replicates were set up as follows:sandy loess, sandy loess mixed with weathered coal, sandy loess mixed with soft rock, sandy loess mixed with soft rock and weathered coal. In July 2013, 12 trial plots of 4 m×5 m were constructed according to the treatments, weathered coal was added uniformly at the dose of 27 t/hm. During August and September in 2014, the soil respiration, temperature and moisture at 5 cm depth were monitored using Li-8100 system. The results showed that: 1) The response of soil respiration to soil temperature could be well simulated by vant’ Huff model;the diurnal variation of sandy loess was a curve with single peak, however, the reconstruction soil with weathered coal addition showed a double-peak curve;weathered coal changed the diurnal variation pattern of soil respiration, and significantly increased soil respiration rate of the soft rock mixed sandy loess and the sandy loess by 35.2%(P<0.05) and 17.1%, respectively. 2) The sensitivity coefficients of soil respiration to the temperature of different reconstruction soils were relatively higher than the regular soils. Multiple linear regression analysis showed that the changes of soil respiration were consistent with soil temperature. And the soil respiration and soil temperature had extremely significant correlation, but soil moisture was not significantly correlated with soil respiration, which meant the soil temperature was the main controlling factor of the change of soil respiration. The results of the experiment can reveal the respiration characteristics of reconstruction soils in a certain degree, and provide a reference for the feasibility assessment of the weathered coal as amendment material to the reconstructed soil in the opencast coal mining region. In conclusion, soil temperature is the decisive factor of soil respiration in arid and semi-arid climatic regions. Objectively speaking, this experiment did not observe the soil respiration under the lower soil water content condition, since soil moisture in this experiment was relatively appropriate in arid regions. Under the condition of soil temperature and water condition in this experiment weathered coal can improve the soil respiration rate, in other words, it will promote the release of soil carbon. So in the practical work, the feasibility of the weathered coal as a new material for soil improvement needs to be further studied from the aspect of the carbon stability.