Impact of nitrogen cycling associated with production and consumption of food on nitrogen pollution of stream water
Impact of nitrogen cycling associated with production and consumption of food on nitrogen pollution of stream water
复制标题
与食品生产和消费相关的氮循环对溪流水氮污染的影响
DOI：
10.1080/00380768.2000.10408788
复制
发表时间：
2000
影响因子：
2
通讯作者：
R. Hatano
中科院分区：
文献类型：
--
作者：
T. Nagumo;R. Hatano
摘要本研究以朝川市7个具有不同土地利用类型的区域为研究对象，评价了氮素循环对水体氮污染的影响，重点研究了人、畜粪便中氮的处理（以下简称“处理N”）以及相对于水体总氮浓度的农田氮富余。为了估计氮循环，我们使用了由人类、牲畜和农田子系统组成的氮流模型。人口密度超过4,000人-2的市区产生了非常大量的处置氮（约2,700公斤/公顷农田-1）。根据处理N的量和生活污水的使用量，估计城市地区的N浓度为34 mg N - L-1，而污水处理设施流出物中的N浓度为24-28 mg N - L-1，与季节无关。结果表明，城区大部分处置氮通过污水处理设施直接排入水体，成为水体氮污染的点源。此外，生猪和家禽养殖区的畜禽设施氮处置量大于其他养殖区，这在一定程度上是氮污染的潜在来源。结果，城市及周边地区的N - L-1浓度均高于1 mg。另一方面，农田氮素过剩实际上是由化肥、畜禽粪便和作物吸收相关的氮流决定的。7个区氮素盈余基本一致，均在69 ~ 99 kg N hm -1 y-1之间。以剩余氮量和50%年平均降水量作为排放率估算的氮浓度为13.6 ~ 19.5 mg N - L-1。大部分剩余氮被滤出。而流经朝日川市的主要河流中，除市区及周边地区外，全氮浓度均低于1 mg N - L-1。即使发生了氮淋溶，农田中多余的氮也可能无法到达河流，这可能是由于植物吸收、反硝化和河岸带和河流通道的沉积对氮的去除。因此，农业实践对水体氮污染的影响不明显。
Abstract We evaluated the impact of nitrogen (N) cycling on N pollution of stream water, with emphasis on N disposed of (hereafter referred to as “disposal N”) from human and livestock excrement and the N surplus in cropland, compared to the total-N concentration of stream water, in seven zones of Asahikawa City characterized by various types of land use. In order to estimate N cycling, we used the Nitrogen Flow Model, composed of the N budgets of human, livestock, and cropland subsystems. The urban area with a population density of over 4,000 persons km-2 generated a very large amount of disposal N (about 2,700 kg N ha-1 cropland y-1). Based on the amount of disposal N and the volume of domestic sewage water used, the N concentration estimated for the urban area was 34 mg N L-1, which found in the effluent from the sewage treatment facility (24–28 mg N L-1), regardless of the season. Thus, it was indicated that most of the disposal N in the urban area was discharged directly to streams through the sewage treatment facilities, contributing to a point source of N pollution of stream water. In addition, the disposal N from livestock facilities was larger in pig and poultry farming areas than in other farming areas, contributing to some extent to a potential source of N pollution. As a result, the concentrations increased above 1 mg N L-1 in the urban and surrounding areas. On the other hand, the N surplus in cropland was practically determined by the N flows associated with chemical fertilizer, livestock excrement as manure, and crop uptake. The N surplus was similar among the seven zones, ranging from 69 to 99 kg N ha-1 y-1. The N concentration estimated from the amount of N surplus and 50% of mean annual precipitation as a discharge rate was 13.6–19.5 mg N L-1. Most of the surplus N was indicated to be leached out. However, the total-N concentration measured in the major streams flowing through Asahikawa City was mostly below 1 mg N L-1 except for the urban and surrounding areas. The surplus N in cropland may not reach the streams, even if N leaching occurs, probably due to N removal by plant uptake, denitrification, and sedimentation in the riparian zone and stream channels. Thus the effect of agricultural practices on N pollution of stream water was not appreciable.