Important contributions of non-fossil fuel nitrogen oxides emissions

Abstract

Since the industrial revolution, it has been assumed that fossil-fuel combustions dominate increasing nitrogen oxide (NOx) emissions. However, it remains uncertain to the actual contribution of the non-fossil fuel NOx to total NOx emissions. Natural N isotopes of NO3− in precipitation (δ15Nw-NO3−) have been widely employed for tracing atmospheric NOx sources. Here, we compiled global δ15Nw-NO3− observations to evaluate the relative importance of fossil and non-fossil fuel NOx emissions. We found that regional differences in human activities directly influenced spatial-temporal patterns of δ15Nw-NO3− variations. Further, isotope mass-balance and bottom-up calculations suggest that the non-fossil fuel NOx accounts for 55 ± 7% of total NOx emissions, reaching up to 21.6 ± 16.6Mt yr−1 in East Asia, 7.4 ± 5.5Mt yr−1 in Europe, and 21.8 ± 18.5Mt yr−1 in North America, respectively. These results reveal the importance of non-fossil fuel NOx emissions and provide direct evidence for making strategies on mitigating atmospheric NOx pollution.

Significant contributions of combustion‐related NH3 and non‐fossil fuel NOx to elevation of nitrogen deposition in southwestern China over past five decades

“…Because values were determined by fractional contributions of dominant NH 3 sources from vehicle exhausts, coal combustion, biomass burning, and wastes and fertilizers (, , , and , respectively) and their δ 15 N values (Table S3), and values were determined by fractional contributions of dominant NO x sources from vehicle exhausts, coal combustion, biomass burning, and microbial N cycles (, , , and , respectively) and their δ 15 N values (Table S3; Liu et al, 2017; Song et al, 2019, 2021), , , , , , , , and can be calculated by the Stable Isotope Analysis in R and based on and values, respectively (detailed in Text S2; shown in Figure S3). Then, we calculated relative contributions between combustion‐related NH 3 (c‐NH 3 ) sources (, the sum of , $$…”

Decadal Variabilities in Tropospheric Nitrogen Oxides Over United States, Europe, and China

“…In contrast to the continental averages (blue solid lines), the sampled satellite measurements match better with surface observations, confirming the reliability of NO 2 observation records provided by OMI, as well as the small influence from other oxidized nitrogen compounds (Lamsal et al., 2015; Liu et al., 2018) on the derived NO 2 trends. Because the density of surface stations (and sampled OMI measurements) is higher over polluted areas, the sampled OMI NO 2 are more strongly affected by local anthropogenic emissions; in contrast, the continental averaged OMI NO 2 are less affected by local anthropogenic emissions (Qu et al., 2021; Silvern et al., 2019; Song et al., 2021; Wang et al., 2021). The discrepancies between continental averaged and sampled OMI NO 2 thus, represent changes of NO 2 background from nonlocal sources, such as natural sources and possible intercontinental pollution transport (Qu et al., 2021; Silvern et al., 2019).…”

“…While NO x emissions are continuously declining in the reported inventories (see Table 1), a recent study (Jiang et al., 2018) reported a marked slowdown in the decrease of tropospheric NO 2 over North America since around 2010. The causes for this unexpected change are debated, with differing explanations involving uncertainties in anthropogenic and natural sources, nonlinear response of NO 2 columns to emissions, and NO x lifetime change (Jiang et al., 2018; Laughner & Cohen, 2019; J. Li & Wang, 2019; Qu et al., 2021; Silvern et al., 2019; Song et al., 2021; Wang et al., 2021), illustrating the challenges in understanding tropospheric NO 2 variations. This debate points to larger, global‐scale questions: are we able to understand the current trends of anthropogenic NO x emissions, the evolution of tropospheric NO 2 , and predict their future projections?…”

Nitrate Water Contamination from Industrial Activities and Complete Denitrification as a Remediation Option

“…Their increasing quantity disturbs the spontaneous biogeochemical N-cycling, halting and modifying the natural ecosystem. N cycling has become more fast-paced with urbanization, as gasoline-powered vehicles and machinery that use fossil fuels that contributing to atmospheric gaseous N species (N 2 O and N 2 ) in developed countries [35,36]. Out of all gaseous N species in the environment, various anthropogenic activities and the many metabolic processes of microorganisms together account for over 85% of the N 2 O in the atmosphere, the accumulation of which results in detrimental conditions in the biosphere [37,38].…”