College of Geomatics, Xi’an University of Science and Technology
Institute of Ecological Environment Restoration in Mine Areas of West China, Xi’an University of Science and Technology
Key Laboratory of Mine Geological Hazards Mechanism and Control, Ministry of Natural Resources
College of Geology and Environment, Xi’an University of Science and Technology
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining Technology-Beijing

深入了解荒漠化露天矿不同土地利用方式下不同深度土壤呼吸昼夜变化规律及影响因子，对评估生态脆弱的露天矿区生态系统碳循环至关重要。以红沙泉露天矿为研究对象，采用EGM-5便携式红外气体观测系统，监测获取不同土地利用类型下不同深度土壤昼夜呼吸速率并获取相关影响因子，分析得到各土地利用类型土壤呼吸变化规律与特征及其主要影响因素。结果表明：① 5种代表性地物类型之间的昼夜土壤呼吸差异显著，10和30 cm土壤呼吸速率日均值表现为人工林 > 红沙泉 > 排土场复垦区 > 柽柳林 > 南线，10 cm分别为5.72、0.98、0.34、0.08、−0.08 μmol/(m2·s)，30 cm分别为5.14、2.18、0.77、0.40、−0.05 μmol/(m2·s)，南线为碳汇，其余4种地物类型为碳源。② 土壤呼吸速率昼夜变化规律明显，排土场复垦区不同土层和红沙泉10 cm土壤呼吸昼夜变化呈“双峰”趋势，人工林、南线不同土层及红沙泉30 cm均呈“单峰型”，而柽柳林10和30 cm土壤呼吸昼夜变化呈“多峰型”。③ 在日尺度上，排土场复垦区、人工林和红沙泉10 cm土壤呼吸速率与土壤温度(P < 0.05)和土壤含水量(P < 0.01)呈显著正相关；土壤温度和土壤含水量能较好的综合解释矿区内5种地物类型土壤呼吸速率50.5%～97.3%的变化，而南线10 cm仅11.3%。土壤温度对柽柳林和南线土壤昼夜呼吸影响较弱，白天土壤温度限制土壤呼吸，而夜间及清晨土壤温度促进土壤呼吸。④ 柽柳林和南线土壤呼吸与土壤碳含量关系与其余3种地物类型不同，与无机碳(SIC)呈显著负相关(相关系数r=0.69, P < 0.01)，无机过程造成土壤呼吸速率为负值，SIC是土壤碳汇的关键影响因素；而排土场复垦区、人工林和红沙泉均与溶解性活性有机碳(DOC)呈较强负相关性，排土场复垦区和柽柳林土壤呼吸还与土壤有机碳(SOC)存在较强正相关性，SOC和DOC是土壤碳源的重要影响因子。综上所述，红沙泉矿区内不同地物类型和不同深度土壤呼吸速率差异显著，不同深度土壤呼吸对土壤温度等环境因子响应存在差异，初步阐明SIC是土壤碳汇的重要因子，SOC和DOC是土壤碳源的重要因子，为矿区碳排放、碳循环提供基础数据。

In-depth understanding of the diurnal variation of soil respiration and its influencing factors at different depths under different land use patterns in desertified open-pit mines is crucial to assessing the carbon cycle of ecosystems in ecologically fragile open-pit mines. Taking the Hongshaquan open-pit mine as the research object, the EGM-5 portable infrared gas observation system was used to monitor and obtain the diurnal respiration rate of soil at different depths under different land use types and obtain related influencing factors. Also, the variation law and characteristics, as well as their main influencing factors of soil respiration under different land use types were got. The results showed that: ① There are significant differences in diurnal soil respiration among the five representative types of land features. The daily average soil respiration rates at 10 and 30 cm depths are ordered as artificial forest > Hongshaquan > reclamation area of dump > tamarisk forest > southern line, at 10 cm depth are 5.72, 0.98, 0.34, 0.08 and −0.08 μmol/(m2·s), respectively, and at 30 cm depth are 5.14, 2.18, 0.77, 0.40 and −0.05 μmol/(m2·s), respectively. The southern line is carbon sink, and the other four types of land features are carbon sources. ② The diurnal variation of soil respiration rate is obvious. The diurnal variation of soil respiration in different soil layers and Hongshaquan at 10 cm depth in the reclamation area of the dump site shows a “double peak” trend. The diurnal variation of soil respiration at 10 and 30 cm depths in tamarisk forest shows a “multi-peak” trend. ③ On the diurnal scale, the soil respiration rate at 10 cm depth in the dump reclamation area, the artificial forest and Hongshaquan is significantly positively correlated with soil temperature (P < 0.05) and soil water content (P < 0.01). The diurnal respiration of soil in the forest and the southern line is weak, and the daytime soil temperature in the tamarisk forest and the southern line limits soil respiration, while the nighttime and early morning soil temperature promotes soil respiration. Soil temperature and soil water content can better explain the variation of soil respiration rate of 50.5%−97.3% for the five feature types in the mine area, while only 11.3% for 10 cm in the southern line. ④ There are differences in the relationship between soil respiration and soil carbon content in tamarisk forest and southern line, and the relationship between the soil respiration and soil carbon content of the other three types of land features. The tamarisk forest and southern line soil respiration have a significant negative correlation with inorganic carbon (SIC) (r=0.69, P < 0.01), the soil respiration rate is negative due to inorganic processes, and SIC is the key factor of soil carbon sink. However, the soil respiration in dump reclamation area, artificial forest and Hongshaquan all have a strong negative correlation with dissolved active organic carbon (DOC). The soil respiration in southern line and tamarisk forest also has a strong positive correlation with soil organic carbon (SOC). SOC and DOC are important factors of soil carbon sources. To sum up, the soil respiration rates of different types of land features and different depths in the Hongshaquan mining area are significantly different, and the responses of soil respiration to soil temperature and other environmental factors are different at different depths. It is preliminarily clarified that SIC is an important factor for soil carbon sinks, while SOC and DOC are important factors for soil carbon sources. The results can provide basic data for carbon emissions and carbon cycle in the mining area.

国家重点研发计划资助项目(2022YFF1303300)；自然资源部矿山地质灾害成灾机理与防控重点实验室开放课题资助项目(2022-07)；陕西省自然科学基础研究计划资助项目(2023-JC-YB-440)

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