School of Geography, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China; Key Laboratory of Virtual Geographic Environment, Ministry of Education, Nanjing Normal University, Nanjing 210023, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China.
School of Geography, Nanjing Normal University, 1 Wenyuan Road, Qixia, Nanjing 210023, China.
Sci Total Environ. 2021 Sep 15;787:147442. doi: 10.1016/j.scitotenv.2021.147442. Epub 2021 May 7.
The nitrogen (N) cascade in rural areas of Changshu County should be measured and evaluated due to the large increase in anthropogenic disturbances in China's Yangtze Delta. Here, we developed a village-scale N flow model using Changshu County and its towns as a case study. The model included four subsystems and was used to describe the driving forces behind the N cascade from agricultural food production and household consumption to the environment (agriculture-food-environment) system. It was found that from 1998 to 2018 the N input increased from 274.63 to 848.65 kg N ha. The cropland N use efficiency (NUEc) decreased by 10.35%, whereas the livestock feed N use efficiency (NUEa) increased by 51.84%. A relatively lower NUE, with a higher N input, was found in Shajiabang Town, which was attributed to hairy crab farming. Changes in dietary patterns led to the food N cost (FNC) being in the range of 4.59-7.74 kg kg. Over the past two decades, the N losses from the agriculture-food-environment system decreased by 45.40% from 12,436.60 t N yr (1998). The contribution of the croplands, livestock-breeding, and household consumption to the N losses were 32.44%, 37.78%, and 29.78%, respectively. About 62.83% of the total N losses entered the water environment. Nitrogen emissions from the croplands accounted for 63.21% of the N losses into the atmosphere. Nitrogen oxide (NO) emissions accounted for 38.50% of the gas emissions, followed by NH (28.36%) and NO (2.81%). The total N losses decreased annually but losses to the water environment increased by 5.10% from 60.16% (1998). The contribution of food production to the total N loss displayed a decreasing trend, while that of food consumption exhibited an increasing trend. Population growth and increased volumes of domestic waste in the Changsu area were the main driving forces for the increased contribution of household food consumption. The significant decline in cropland area and increase in built-up and heavily trafficked areas indicated an overall increase in anthropogenic disturbances, stimulating the N cascade in the Yangtze Delta from 1998 to 2018.
由于中国长江三角洲地区人为干扰的大量增加，常熟县农村地区的氮（N）级联需要进行测量和评估。在这里，我们以常熟县及其城镇为例，开发了一个村庄规模的 N 流模型。该模型包括四个子系统，用于描述从农业食品生产和家庭消费到农业-食品-环境系统的 N 级联的驱动力。结果表明，1998 年至 2018 年，N 输入量从 274.63 千克 N/公顷增加到 848.65 千克 N/公顷。农田 N 利用效率（NUEc）下降了 10.35%，而牲畜饲料 N 利用效率（NUEa）增加了 51.84%。沙家浜镇的 NUE 相对较低，N 输入量较高，这归因于毛蟹养殖。饮食模式的变化导致食品 N 成本（FNC）在 4.59-7.74 千克 N/千克之间。在过去的二十年中，农业-食品-环境系统的 N 损失从 1998 年的 12436.60 吨 N/年减少了 45.40%。农田、畜牧业和家庭消费对 N 损失的贡献分别为 32.44%、37.78%和 29.78%。大约 62.83%的总 N 损失进入水环境。农田氮排放占大气氮损失的 63.21%。氮氧化物（NO）排放量占气体排放量的 38.50%，其次是氨（28.36%）和一氧化氮（2.81%）。总 N 损失逐年减少，但 1998 年以来，水环境损失增加了 5.10%，达到 60.16%。食品生产对总 N 损失的贡献呈下降趋势，而食品消费的贡献呈上升趋势。常熟地区人口增长和城市生活垃圾量增加是家庭食品消费贡献增加的主要驱动力。农田面积的显著减少和建成区及交通繁忙区的增加表明，人为干扰的总体增加，刺激了 1998 年至 2018 年长江三角洲地区的 N 级联。
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