壤中流驱动下可溶性有机碳迁移的研究进展

Advances of the migration of dissolved organic carbon driven by interflow

土壤碳库的相对稳定是保持土壤肥力、维持碳素平衡和应对全球气候变化的重要途径。土壤侵蚀尤其水力侵蚀是土壤碳库命运的重要影响因子,土壤碳的侵蚀损失受到持续和普遍关注;但是目前水力侵蚀作用下土壤碳素动态研究主要着重于地表径流和泥沙,而对壤中流驱动下的碳素(主要是可溶性有机碳DOC)损失研究较少涉及。对部分壤中流发育发达的土壤剖面而言,DOC的迁移损失不仅是碳素损失的重要途径,也会影响到水体环境和人类健康,理应受到更多关注。在简要概括水力侵蚀过程中有机碳随地表径流和侵蚀泥沙的迁移以及矿化释放等关键过程的基础上,重点阐述了国内外不同生态系统壤中流驱动下DOC的迁移通量及其迁移机制2方面的研究进展。在迁移通量方面,国外着重于森林和草地生态系统,而国内偏重于耕地。在迁移机制方面,国内外都是主要关注降雨因素(包括降雨量和降雨强度)对DOC迁移过程和迁移通量的影响。在此基础上总结现有研究的不足,指出今后需在研究内容(径流入渗过程中土壤DOC的再分配及其影响因素、DOC和可溶性有机氮DON的同步监测)、研究对象(红壤坡耕地)和研究手段(自然降雨背景下野外坡耕地原位定位观测)3方面加强研究,以期对相关领域的研究起到一定程度的推动作用。

[Background]Soil carbon(C)pool is regulated by water erosion on slope or watershed scale.Water erosion is a major driver to C redistribution over terrestrial landscapes and export into aquatic systems.Due to the vital function of soil organic carbon(SOC)in sustainable social and environmental development,SOC migration and its loss accompanied by soil erosion(especially water erosion)have attracted continuous and global attentions.At present,the study of soil C dynamics under water erosion mainly focused on the migration driven by surface runoff and sediment.However,dissolved organic carbon(DOC)migration driven by interflow remains largely unknown.For some well-developed interflow soils,DOC migration is not only an important way of soil C loss,but also can affect the water environment and human health.[Methods]In this study,the research progresses of DOC migration and its main driving forces driven by interflow in typical ecosystems were reviewed,based on a brief summary of the overall dynamics of SOC under water erosion.[Results]1)DOC migration fluxes have been well documented in the world.Foreign studies focused on the loss of DOC in forest ecosystems and grassland ecosystems.The DOC migration fluxes in some agricultural ecosystems were bigger than that in natural ecosystems,which needs more attention.2)Recently,the study of DOC migration driven by interflow has gradually increased in China,including some agricultural ecosystems in different erosion type areas,such as northeast black soil area,Sichuan purple soil area,Southwest karst area and southern red soil area.Especially the DOC migration driven by interflow in slope land in purple soil area has attracted more attentions.Many studies showed that the vertical migration of DOC accounted for a large proportion in the total SOC loss in sloping land of purple soil.3)Rainfall was the main natural factor for DOC migration,including rainfall and rainfall intensity.Rainfall was the decisive factor for DOC migration flux;however DOC migration concentration was closely related to rainfall intensity.4)For agricultural ecosystems,the effects of fertilization and cultivation on DOC migration have also attracted many attentions.Generally,the application of fertilizer,especially the organic fertilizer could increase DOC migration flux.[Conculsions]The main research directions in this field in the future are suggested,including research contents(DOC redistribution and its influencing factors in soil profile and synchronous monitoring of DOC and dissolved organic nitrogen),research objects(sloping cropland in red soil regions)and research methods(in-situ observation under natural rainfall).