Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China

Abstract

Abstract. Emissions of reactive nitrogen (N) species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, threeyear average of 60.6 kg N ha −1 yr −1 . The deposition levels showed spatial and temporal variation in the range of 28.5-100.4 kg N ha −1 yr −1 . Of the annual total deposition, 40 % was deposited via precipitation, and the remaining 60 % was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10 % to the total flux. On an annual basis, oxidized species accounted for 21 % of total N deposition, thereby implying that other forms of gaseous N, such as NH 3 , comprised a dominant portion of the total flux. The contribution of NO − 3 to N deposition was enhanced in certain urban and industrial areas, possibly due to the fossil fuse combustion. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH 3 dry deposition. Taken together, these findings show that NH 3 emissions should be abated to mitigate high N deposition and associated potential impacts on ecosystems in Northern China. The present results improve our understanding of spatio-temporal variations of magnitudes, pathways and species of deposited N in the target areas, and are important not only to inform conservation and regulatory bodies but also to initiate further detailed studies. Uncertainties among current observations underscore the need to quantify the impact of vegetation on dry deposition and to refine the simulation of dry deposition velocity.

Dry deposition of nitrogen compounds (NO<sub>2</sub>, HNO<sub>3</sub>, NH<sub>3</sub>), sulfur dioxide and ozone in west and central African ecosystems using the inferential method

“…The inferential technique has been widely used in other studies for different types of ecosystems (Shen et al, 2009;Pineda and Venegas, 2009;Jin et al, 2006;Zhang et al, 2005Zhang et al, , 2009Delon et al, 2010Delon et al, , 2012and Pan et al, 2012). This approach is more suited when routine monitoring data are available but the values of the derived fluxes are clearly dependent on the validity of the dry deposition velocity calculation.…”

Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution

“…Both are aboard the NASA Aura satellite in a sun-synchronous orbit with an ascending equator crossing time of 13:45 LT (Beer, 2006). We evaluate model simulated wet deposition fluxes of ammonium and nitrate with observational data from the Acid Deposition Monitoring Network in East Asia (EANET; data available at http://www.eanet.asia/index.html) and 10 sites monitored by the Chinese Academy of Science (CAS) located in North China (Pan et al, 2012). Measurements of nitrogen dry deposition fluxes are rather limited over the northwestern Pacific.…”

Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

“…To investigate the spatial and temporal variations in atmospheric NO 2 and NH 3 , ground measurements are acknowledged to be an effective way of monitoring the accurate concentrations of NO 2 and NH 3 Pan et al, 2012;Meng et al, 2010). Ground measurements of NO 2 concentrations in China, including about 500 stations in 74 cities, have been monitored and reported to the public since January 2013 (Xie et al, 2015).…”

“…Atmospheric reactive N emissions are dominated by nitrogen oxides (NO x = NO + NO 2 ) and ammonia (NH 3 ; Li et al, 2016;Galloway et al, 2004). Atmospheric NO 2 and NH 3 are the most important precursors for N r compounds including N 2 O 5 , HNO 3 , HONO and particulate NO − 3 and NH + 4 in the atmosphere Pan et al, 2012). Therefore, an understanding of both the spatial and temporal patterns of NO 2 and NH 3 is essential for evaluating N-enriched environmental effects, and can provide the scientific background for N pollution mitigation.…”