陇中盆地中新世土壤呼吸历史及其对东亚夏季风的响应

Miocene soil respiration history in Longzhong Basin and its response to East Asian summer monsoon

  • 摘要: 土壤呼吸作用是土壤碳循环研究的重要环节,查明呼吸作用产生的二氧化碳浓度、土壤呼吸速率及影响因素对理解土壤碳循环至关重要。目前更多的研究集中于现代土壤呼吸作用,地质历史时期的土壤呼吸报道很少。中中新世作为预测未来气候变化的相似期,其土壤呼吸的研究可以为未来高二氧化碳浓度下气候变化提供借鉴。报道了陇中盆地天水莲花剖面中新世以来碳酸盐结核的δ13CPC以及碳酸盐结核内包含的δ13Com,并重建了中新世土壤呼吸速率以及土壤呼吸释放的二氧化碳浓度。结果显示,土壤呼吸速率为150~400 gC·m−2·a−1,土壤呼吸释放的二氧化碳为700×10−6~2 400×10−6。土壤呼吸释放的二氧化碳以及土壤呼吸速率都显示在中中新世暖期增高,在早中新世及晚中新世土壤呼吸释放的二氧化碳以及土壤呼吸速率下降,这种变化与东亚夏季风降水变化趋势一致,指示暖湿气候增强了土壤呼吸作用。

     

    Abstract: Soil respiration is an important link in the study of soil carbon cycle, for which understanding the soil respired carbon dioxide concentration, soil respiration rate, and the influencing factors is important. Most present studies focus on modern soil respiration and few concerned that in geological history. Taking the Miocene Lianhua Section, Longzhong Basin in Tianshui, Gansu, NW China as a case of an ancient analogue and as a reference point for predicting future climate change under high carbon dioxide concentration, we studied and compared the δ13C values of the organic matter in carbonate nodules (δ13Com) and that of the inorganic matter in pedogenic carbonate nodules (δ13Cpc) from the section, from which the soil respiration rate and soil respired carbon dioxide concentration during the Miocene were reconstructed. Results show that the soil respiration rate ranged 150~400 gC·m−2·a−1 and the carbon dioxide released from soil respiration ranged (700~2400)×10−6. Both soil respired CO2 and soil respiration rate were shown increased during the Middle Miocene warm period, and the soil respired CO2 and soil respiration rate decreased before and after the Middle Miocene. This change is consistent with the East Asian summer precipitation, indicating that warm-wet climate enhanced soil respiration.

     

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