Significant Latitudinal Gradient of Nitrate Production in the Marine Atmospheric Boundary Layer of the Northern Hemisphere

Abstract

Nitrate (NO 3 − , including particulate (NO 3 − (p) ) and gas-phase nitric acid (HNO 3(g) )), the final product of nitrogen oxides (NO x , NO x = NO + NO 2 ), is ubiquitous in the atmosphere and plays a critical role in biogeochemical cycles (Galloway et al., 2008). Previous observations and model simulations suggested that atmospheric deposition contributes to up to one-third of external inputs of oceanic nitrogen, and increased nitrogen concentrations in ocean surface waters have been observed with the intensification of atmospheric NO 3 − deposition (Duce et al., 2008;Jickells et al., 2017;Kim et al., 2011). On the other hand, ocean emissions (e.g., alkyl nitrates (RONO 2 )) can also act as a source of atmospheric NO x , potentially influencing the budget of NO 3 − in the marine atmospheric boundary layer (MABL) (

Continental Emissions Influence the Sources and Formation Mechanisms of Marine Nitrate Aerosols in Spring Over the Bohai Sea and Yellow Sea Inferred From Stable Isotopes

“…The contribution of (NO 3 + HC/DMS) to nitrate in the BNYS was relatively high, resulting in a negative mean ε value. Our ε value in the BNYS was in line with that (−1.8‰) in the MBL (50–70°N) (Li, Shi, et al., 2022) of the Northern Hemisphere where the P2 pathway dominated nitrate formation. Since the δ 15 N value would change from NO x to nitrate, the δ 15 N–NO 3 − values in aerosol samples had to be corrected by subtracting their corresponding ε values and then served as input data in the SIAR model.…”

“…As well known, nitrate has been identified as the primary contributor to WSIs in aerosols in several cities in eastern China. Studies conducted in Changchun (Zhao et al., 2020), Beijing (Fan et al., 2020), Tianjin (Zhang et al., 2022), Jiaozuo (Li, Geng, et al., 2022), Li, Shi, et al., 2022nd Shanghai (Sun et al., 2022) have all reported the significant role played by nitrate in atmospheric aerosols in urban agglomerations in this region. The consistent high nitrate contribution of aerosols in the northern seas as well as in nearby continental areas like the North China Plain and Northeast China, suggests that the significant differences in nitrate concentrations and isotope characteristics between the northern and southern seas maybe attributed to continental outflow.…”

“…On the contrary, the relative fractions of NO 3 + HC/DMS and N 2 O 5 hydrolysis to nitrate exhibited the opposite distributions which increased in the high‐latitude regions. NO 3 + HC/DMS is typically considered as one of the nocturnal pathways, however, Li, Shi, et al., 2022) suggested that the contribution of nitrate formed by this pathway can be as high as 45% at high‐latitude oceans (50–70°N) even in the summertime. In recent years, some studies highlighted the significant role of NO 3 + HC pathway in nitrate formation in China.…”

“…δ 15 N isotopic fractionation occurs between NO 2 and NO x , NO 2 and NO 3 , and NO 2 and N 2 O 5 (Walters & Michalski, 2016), resulting in a total δ 15 N isotopic fractionation value expressed as the sum of the fractionation between NO 2 and NO x and the fractionation between NO 2 and NO 3 − . This overall fractionation value varies with the relative contributions of the different nitrate formation mechanisms (Li, Shi, et al., 2022; Walters & Michalski, 2016). Our results indicated that the δ 15 N isotopic fractionation between NO 2 and NO 3 was negative with an average value of −18.5‰.…”

Formation Mechanisms and Source Apportionments of Nitrate Aerosols in a Megacity of Eastern China Based On Multiple Isotope Observations

“…(2020). However, the δ 18 O‐NO 3 − values in Hangzhou were much higher than those observed in the MBL (37.6‰–76.7‰, mean = 61.7‰; Y. Li et al., 2022), indicating different formation mechanisms of nitrate aerosols between urban and marine regions. In this study, δ 18 O‐NO 3 − was positive correlated with Δ 17 O‐NO 3 − ( r = 0.59, P < 0.01).…”