Environmental Pollution：亞熱帶農業小流域大氣活性氮排放、沉降與收支研究

【歡迎您關注--農業環境科學】

中國科學院亞熱帶農業生態研究所土壤生態與環境課題組以典型亞熱帶農業小流域——金井河流域為研究物件，監測了流域內稻田、森林和茶園的大氣活性氮幹、溼沉降，編制了流域NH3和NOx排放清單。相關成果發表於

Environmental Pollution

（IF=8。071）。

研究工作得到國家重點研發計劃、國家自然科學基金和中科院青年創新促進會的支援。

閱讀論文全文請點選文末

閱讀原文

。

Highlights

Mean atmospheric Nr deposition was 36 kg N ha1 yr1 in a subtropical catchment in a 2-yr study。

Total Nr emissions in catchment were 80 kg N ha1 yr1， with 62 kg N ha1 yr1 from NH3 emissions。

The net Nr budget showed high emissions due to NH3 emissions from livestock and fertilization。

Paddy and tea fields were net sources of Nrs， while forest was a net strong sink of Nrs。

Abstract

The study of emissions and depositions of atmospheric reactive nitrogen species （Nrs） in a region is important to uncover the sources and sinks of atmospheric Nrs in the region。 In this study， atmospheric total Nrs depositions including both wet-only and dry deposition were monitored simultaneously across major land-use types in a 105 km2 catchment called Jinjing River Catchment （JRC） in subtropical central China from 2015 to 2016。 Based on activity data and emission factors for the main Nrs emission sources， ammonia （NH3） and nitrogen oxides （NOx） emission inventories for the catchment were also compiled。 The estimated total Nrs deposition in JRC was 35。9 kg N ha1 yr1， with approximately 49。7 % attributed to reduced compounds （NHx）， and 40。5 % attributed to oxidized （NOy）。 The total Nrs emission rate in JRC was 80。4 kg N ha1 yr1， with 61。5 and 18。9 kg N ha1 yr1 from NH3 and NOx emissions， respectively。 Livestock excretion and fertilization were the two main contributing emission sources for NH3， while vehicle sources contributed the bulk of NOx emissions。 The net atmospheric budgets of Nrs in paddy field， forest， and tea field were +3。7， 36。1， and +23。8 kg N ha1 yr1， respectively。 At the catchment scale， the net atmospheric budget of Nrs was +47。7 kg N ha1 yr1， with +43。7 kg N ha1 yr1 of NHx and +4。0 kg N ha1 yr1 of NOy， indicating that the subtropical catchment was net sources of atmospheric Nrs。 Considering that excessive atmospheric Nr emissions and deposition may cause adverse effects on the environment， effects should be conducted to mitigate the Nrs emissions from agriculture and transportation， and increasing the area of forest is good for reducing the net positive budget of atmospheric Nrs in the subtropical catchments in China。

大氣活性氮排放與沉降研究對於揭示大氣活性氮的源與匯有重要意義。隨著我國經濟的快速發展，畜禽養殖數量、化學氮肥使用量以及化石燃料消耗量不斷增加，排放到大氣中的氨氣（NH3）及氮氧化合物（NOx）也呈持續增加態勢，大氣中的活性氮最終透過幹、溼沉降返回地表，從而導致灰霾汙染、土壤和水體酸化、生態系統多樣性喪失等生態問題。

我國亞熱帶地區佔我國土地面積的四分之一，其中廣泛分佈著農業小流域，是大氣活性氮排放和沉降的熱點區域。因此，量化亞熱帶農業小流域大氣活性氮排放、沉降和收支，對於揭示大氣活性氮的源與匯十分重要。然而，亞熱帶農業小流域大氣活性氮收支研究鮮有報道。

基於此，中國科學院亞熱帶農業生態研究所土壤生態與環境課題組以典型亞熱帶農業小流域——金井河流域為研究物件，監測了流域內三種主要土地利用型別（稻田、森林和茶園）的大氣活性氮幹、溼沉降。此外，研究人員基於排放因子法，透過流域調查和文獻調研獲取活動資料，編制了流域NH3和NOx排放清單。研究表明，流域內大氣活性氮總沉降量為35。9 kg N ha-1 yr-1，其中還原態（NHx）與氧化態（NOy）活性氮分別佔49。7%和40。5%。流域內NH3排放與NOx排放速率分別為61。5 kg N ha-1 yr-1和18。9 kg N ha-1 yr-1。其中，畜禽源和交通源分別是NH3和NOx排放清單的主要排放源。綜合流域內排放與沉降研究表明，稻田、森林和茶園的淨大氣活性氮收支分別為+3。7、-36。1 kg N ha-1 yr-1和+23。8 kg N ha-1 yr-1，而流域尺度為+47。7 kg N ha-1 yr-1（+為排放，-為沉降），表明森林是重要的大氣活性氮的匯，而亞熱帶農業小流域或是大氣活性氮的源。