华北平原农田关键带分类研究

Classification of agricultural critical zones in the North China Plain

地球关键带是大气圈、水圈、生物圈、岩石圈、土壤圈相互作用并发生物质迁移转化的区域,也是决定人类社会生存和发展的关键区域。我国学者根据土地利用的差异对地球关键带开展了分类,其中农田关键带是人类活动影响最为强烈的一类。但已有研究更多考虑的是地表要素,包含包气带和含水层方面的要素较少,对关键带地下部分的属性关注不够。华北平原作为我国重要粮食高产区,地下水超采严重,农业生产引起的环境污染风险日益引发关注。开展农田关键带分类研究可以为该区域地下水水量/水质演化及保护提供基础科学支撑。本研究综合考虑华北平原的第四纪沉积物特征、浅层地下水埋深、地下水矿化度以及农业土地利用类型等要素,在遵循综合性原则和主导因素原则的基础上,制定了华北平原农田关键带三级分类方案。通过使用叠置法对分类要素进行叠加和合并,提出了华北平原农田关键带的分类方案,将华北平原分为38个农田关键带类型。本研究对于深入认识农业活动对地下水环境的影响具有重要意义。

The Earth’s critical zone is an area where water and solutes,as well as energy,gases,solids,and organisms,are exchanged among the atmosphere,hydrosphere,biosphere,lithosphere,and pedosphere,creating a life-sustaining environment for human society.In the vertical direction,the Earth’s critical zone goes up to the plant canopy and down through soil layers,unsaturated vadose zones,and saturated aquifers.Laterally,the Earth’s critical zones include not only weathered loose strata but also lakes,rivers,shallow marine environments,and vegetation.Earth’s critical zone studies mostly focus on the interaction between air,water,organisms,soil,surface rocks,and soil,integrating aboveground and belowground,time and space,and living and abiotic factors.This provides a basis for a comprehensive analysis of the evolution of complex terrestrial ecosystems and interdisciplinary research.The critical zones of the Earth are classified according to the differences in land use,among which the agricultural critical zone is the most strongly affected by human activities.However,most studies only consider surface function elements,without considering the important elements in the vadose zone and aquifers.The North China Plain(NCP)is a highly productive region where groundwater overexploitation and pollution are the major concerns.The crop-soil-aquifer critical zone perspective can provide new ideas for groundwater protection.Classification of the agricultural critical zone is the early basis for the study of regional groundwater volume/quality evolution and spatial differences.However,there has been little research on the classification of critical agricultural zones in the NCP.The classification of the agricultural critical zones in the NCP refers to the scheme for a comprehensive natural zone to a certain extent.By analyzing the hydrogeological conditions of the area and other information,combined with regional characteristics,the new classification followed the principles of comprehensiveness and dominant factors were developed with a three-level classification scheme for agricultural critical zones in the NCP by comprehensively considering the quaternary geology and geomorphology,shallow groundwater salinity,groundwater table depth,and agricultural land use factors.Taking the NCP as an example,agricultural critical zone zoning and mapping were carried out using the superposition method to superimpose and merge the classification elements,and an agricultural zone classification scheme was proposed.Finally,the results of this study divided the agricultural critical zone in the North China Plain into three first-level units,13 second-level units,and 38 third-level units.This study has important reference significance for promoting the development of Earth critical zones,systematically understanding agricultural activities and their impacts on critical zone processes,and conducting research on the integrated management of regional groundwater and natural resources based on protection.