当你穿越秦岭-淮河线时,你会发现在此线的南北两面,农业差异明显。我们可以将此归因于气候差异。北方的气候更干燥、寒冷,而南方则相反,这种差异导致了不同类型的农业。~1 China, or officially the People’s Republic of China, is a ...当你穿越秦岭-淮河线时,你会发现在此线的南北两面,农业差异明显。我们可以将此归因于气候差异。北方的气候更干燥、寒冷,而南方则相反,这种差异导致了不同类型的农业。~1 China, or officially the People’s Republic of China, is a country in East Asia that is home to more than 1.4 billion people.展开更多
This article utilizes a large quantity of data compiled and extracted from local gazetteers to examine the management of extensive agriculture in North China. The author finds that disrepair of fields and lrrigation, ...This article utilizes a large quantity of data compiled and extracted from local gazetteers to examine the management of extensive agriculture in North China. The author finds that disrepair of fields and lrrigation, a lack of animal power, primitive management styles, low per unit yields,and waterlogging were concrete manifestation of the regions extensive agriculture. Due to the practice of extensive agriculture, labor productivity per unit of land, technology, and capital investment were all inadequate. This restricted agricultural output and development of more efficient grain and labor productivity. Thus, using the theory of" involution" to explain North China’s underdevelopment of labor productivity does not fit reality, at least not for the Qing dynasty.展开更多
华北大气污染区域化正在对农业生态区域产生显著影响,为了了解华北农业地区大气细颗粒物PM_(2.5)的季节分布特征,2017年7月、9月、12月以及2018年4月在中国科学院禹城农业生态综合实验站进行分季节PM_(2.5)样品采集,并测定分析了样品中3...华北大气污染区域化正在对农业生态区域产生显著影响,为了了解华北农业地区大气细颗粒物PM_(2.5)的季节分布特征,2017年7月、9月、12月以及2018年4月在中国科学院禹城农业生态综合实验站进行分季节PM_(2.5)样品采集,并测定分析了样品中31种化学成分。结果表明,碳质气溶胶总体的浓度水平为13.11±8.37μg m^(−3),有机碳(OC)冬春季节浓度较高,元素碳(EC)浓度在秋冬季节较高。同时OC/EC的比值在秋季明显偏低,表明在秋季二次碳质气溶胶对PM_(2.5)贡献较小。水溶性离子浓度总体在冬季最高。NO_(3)^(-)/SO_(4)^(2-)比值在夏季明显偏低为0.69,华北地区夏季固定点源对大气污染的贡献相对较高。PM_(2.5)中金属元素以Na、Mg、Al、Ca、K、Fe等地壳元素为主,具有致癌风险的Co、Cr、Ni、Pb、As等金属元素年均浓度为0.32±0.24 ng m^(−3)、5.40±5.42 ng m^(−3)、10.23±7.46 ng m^(−3)、42.23±27.75 ng m^(−3)、5.66±3.79 ng m^(−3)。受体模型(PMF)计算结果表明,PM_(2.5)的主要来源为二次污染源、生物质燃烧源、燃煤燃油源、柴油车尾气和土壤源,贡献率分别达37.1%、18.2%、14.2%、9.4%和7.9%,表明农业区细颗粒物污染受到华北工业、农业与自然排放的多重影响。展开更多
Climate change is having a considerable impact on the availability of water resources for agricultural production on the North China Plain （NCP）, where the shortage of water is currently disturbing the stability and...Climate change is having a considerable impact on the availability of water resources for agricultural production on the North China Plain （NCP）, where the shortage of water is currently disturbing the stability and sustainability of agricultural production with respect to the drying tendency since the 1950s. However, although potential evapotranspiration （ET） has shown a decreasing trend under climate change, actual ET has slightly increased with an acceleration in hydrological cycling. Global climate model （GCM） ensemble projections predict that by the 2050s, the increased crop water demand and intensified ET resulting from global warming will reduce water resources surplus （Precipitation-ET） about 4%-24% and increase significantly the irrigation water demand in crop growth periods. This study assesses possible mitigation and adaptation measures for enabling agricultural sustainability. It is revealed that reducing the sowing area of winter wheat （3.0%-15.9%） in water-limited basins, together with improvement in crop water-use efficiency would effectively mitigate water shortages and intensify the resilience of agricultural systems to climate change.展开更多
文摘当你穿越秦岭-淮河线时,你会发现在此线的南北两面,农业差异明显。我们可以将此归因于气候差异。北方的气候更干燥、寒冷,而南方则相反,这种差异导致了不同类型的农业。~1 China, or officially the People’s Republic of China, is a country in East Asia that is home to more than 1.4 billion people.
文摘This article utilizes a large quantity of data compiled and extracted from local gazetteers to examine the management of extensive agriculture in North China. The author finds that disrepair of fields and lrrigation, a lack of animal power, primitive management styles, low per unit yields,and waterlogging were concrete manifestation of the regions extensive agriculture. Due to the practice of extensive agriculture, labor productivity per unit of land, technology, and capital investment were all inadequate. This restricted agricultural output and development of more efficient grain and labor productivity. Thus, using the theory of" involution" to explain North China’s underdevelopment of labor productivity does not fit reality, at least not for the Qing dynasty.
文摘华北大气污染区域化正在对农业生态区域产生显著影响,为了了解华北农业地区大气细颗粒物PM_(2.5)的季节分布特征,2017年7月、9月、12月以及2018年4月在中国科学院禹城农业生态综合实验站进行分季节PM_(2.5)样品采集,并测定分析了样品中31种化学成分。结果表明,碳质气溶胶总体的浓度水平为13.11±8.37μg m^(−3),有机碳(OC)冬春季节浓度较高,元素碳(EC)浓度在秋冬季节较高。同时OC/EC的比值在秋季明显偏低,表明在秋季二次碳质气溶胶对PM_(2.5)贡献较小。水溶性离子浓度总体在冬季最高。NO_(3)^(-)/SO_(4)^(2-)比值在夏季明显偏低为0.69,华北地区夏季固定点源对大气污染的贡献相对较高。PM_(2.5)中金属元素以Na、Mg、Al、Ca、K、Fe等地壳元素为主,具有致癌风险的Co、Cr、Ni、Pb、As等金属元素年均浓度为0.32±0.24 ng m^(−3)、5.40±5.42 ng m^(−3)、10.23±7.46 ng m^(−3)、42.23±27.75 ng m^(−3)、5.66±3.79 ng m^(−3)。受体模型(PMF)计算结果表明,PM_(2.5)的主要来源为二次污染源、生物质燃烧源、燃煤燃油源、柴油车尾气和土壤源,贡献率分别达37.1%、18.2%、14.2%、9.4%和7.9%,表明农业区细颗粒物污染受到华北工业、农业与自然排放的多重影响。
基金Acknowledgment This work was supported by the State＇s Key Project of Research and Development Plan （2010CB428404） and the Natural Science Foundation of China （41471026）.
文摘Climate change is having a considerable impact on the availability of water resources for agricultural production on the North China Plain （NCP）, where the shortage of water is currently disturbing the stability and sustainability of agricultural production with respect to the drying tendency since the 1950s. However, although potential evapotranspiration （ET） has shown a decreasing trend under climate change, actual ET has slightly increased with an acceleration in hydrological cycling. Global climate model （GCM） ensemble projections predict that by the 2050s, the increased crop water demand and intensified ET resulting from global warming will reduce water resources surplus （Precipitation-ET） about 4%-24% and increase significantly the irrigation water demand in crop growth periods. This study assesses possible mitigation and adaptation measures for enabling agricultural sustainability. It is revealed that reducing the sowing area of winter wheat （3.0%-15.9%） in water-limited basins, together with improvement in crop water-use efficiency would effectively mitigate water shortages and intensify the resilience of agricultural systems to climate change.
