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首页> 外文会议>2nd International Nitrogen Conference , Oct 14-18, 2001, Potomac, Maryland, USA >Emissions of Nitrous Oxide and Nitric Oxide from Soils of Native and Exotic Ecosystems of the Amazon and Cerrado Regions of Brazil
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Emissions of Nitrous Oxide and Nitric Oxide from Soils of Native and Exotic Ecosystems of the Amazon and Cerrado Regions of Brazil

机译：巴西亚马逊河和塞拉多地区原生和外来生态系统土壤中一氧化二氮和一氧化氮的排放

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This paper reviews reports of nitrous oxide (N_2O) and nitric oxide (NO) emissions from soils of the Amazon and Cerrado regions of Brazil. N_2O is a stable greenhouse gas in the troposphere and participates in ozone-destroying reactions in the stratosphere, whereas NO participates in tropo-spheric photochemical reactions that produce ozone. Tropical forests and savannas are important sources of atmospheric N_2O and NO, but rapid land use change could be affecting these soil emissions of N oxide gases. The five published estimates for annual emissions of N_2O from soils of mature Amazonian forests are remarkably consistent, ranging from 1.4 to 2.4 kg N ha~(-1) year~(-1), with a mean of 2.0 kg N ha~(-1) year~(-1). Estimates of annual emissions of NO from Amazonian forests are also remarkably similar, ranging from 1.4 to 1.7 kg N ha~(-1) year~(-1), with a mean of 1.5 kg N ha~(-1) year~(-1). Although a doubling or tripling of N_2O has been observed in some young (≤2 years) cattle pastures relative to mature forests, most Amazonian pastures have lower emissions than the forests that they replace, indicating that forest-to-pasture conversion has, on balance, probably reduced regional emissions slightly (<10%). Secondary forests also have lower soil emissions than mature forests. The same patterns apply for NO emissions in Amazonia. At the only site in Cerrado where vegetation measurements have been made N_2O emissions were below detection limits and NO emissions were modest (～0.4 kg N ha~(-1) year~(-1)). Emissions of NO doubled after fire and increased by a factor of ten after wetting dry soil, but these pulses lasted only a few hours to days. As in Amazonian pastures, NO emissions appear to decline with pasture age. Detectable emissions of N_2O have been measured in soybean and corn fields in the Cerrado region, but they are modest relative to fluxes measured in more humid tropical agricultural regions. No measurements of NO from agricultural soils in the Cerrado region have been made, but we speculate that they could be more important than N_2O emissions in this relatively dry climate. While a consistent pattern is emerging from these studies in the Amazon region, far too few data exist for the Cerrado region to assess the impact of land use changes on N oxide emissions.
机译：本文回顾了巴西亚马逊河和塞拉多地区土壤中一氧化二氮（N_2O）和一氧化氮（NO）排放的报告。 N_2O是对流层中的一种稳定的温室气体，并在平流层中参与破坏臭氧的反应，而NO参与产生臭氧的对流层光化学反应。热带森林和稀树草原是大气中N_2O和NO的重要来源，但土地使用的快速变化可能会影响这些土壤中N氧化物气体的排放。五个已发表的关于亚马逊河流域成熟森林土壤年N_2O排放的估计值非常一致，范围从1.4到2.4 kg N ha〜（-1）年〜（-1），平均为2.0 kg N ha〜（- 1）年〜（-1）。亚马逊森林的NO排放估算也非常相似，范围从1.4到1.7 kg N ha〜（-1）年〜（-1），平均为1.5 kg N ha〜（-1）年〜（ -1）。尽管相对于成熟的森林，在某些年轻（≤2年）的牛牧场中已观察到N_2O翻了一倍或三倍，但大多数亚马逊草牧场的排放量都低于其替代的森林，这表明从森林到牧场的转化总体上是平衡的，可能会略微减少区域排放（<10％）。次生林的土壤排放也比成熟林低。同样的模式适用于亚马逊地区的NO排放。在塞拉多唯一进行植被测量的地点，N_2O排放量低于检测极限，NO排放量不高（约0.4 kg N ha〜（-1）年〜（-1））。火灾后，NO的排放量增加了一倍，而在干燥的土壤中润湿后，其排放量增加了十倍，但这些脉冲仅持续了几小时到几天。像亚马逊草场一样，NO的排放似乎随着草龄的增长而下降。在塞拉多地区的大豆和玉米田中已检测到可检测到的N_2O排放，但相对于较湿润的热带农业地区所测得的通量而言，这些排放量相对较小。没有对塞拉多地区的农业土壤中的一氧化氮进行测量，但是我们推测，在这种相对干燥的气候中，它们可能比N_2O排放更为重要。尽管在亚马逊地区的这些研究中出现了一个一致的模式，但对于塞拉多地区而言，评估土地利用变化对一氧化氮排放的影响的数据很少。

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