Dry-deposition of inorganic and organic nitrogen aerosols to the Arabian Sea: Sources, transport and biogeochemical significance in surface waters
Dry-deposition of inorganic and organic nitrogen aerosols to the Arabian Sea: Sources, transport and biogeochemical significance in surface waters
复制标题
DOI：
10.1016/j.marchem.2021.103938
复制
发表时间：
2021-02
期刊：
影响因子：
3
通讯作者：
P. Bikkina;V. Sarma;K. Kawamura;S. Bikkina
中科院分区：
文献类型：
--
作者：
P. Bikkina;V. Sarma;K. Kawamura;S. Bikkina
水溶性总氮（WNTN）的海气沉降影响着近岸海洋的初级生产力。在这里，我们评估了冬季（SS 379：2018年12月6日至24日）阿拉伯海上空的气溶胶无机（WSIN：NH 4 ++ NO3−）和水分的浓度。NH 4+的平均浓度（109 ± 83 nmol m−3）超过了NO3−（32 ± 13 nmol m−3）和水溶性有机氮（WSON：WSTN-WSIN：86 ± 81 nmol m−3）的平均浓度，约占Wessel质量的50 ± 31%。WSON与水溶性有机碳和NH 4+与非海盐（NSS）-K+的显着线性关系，表明它们共同的起源于生物质燃烧和肥料。反向气团轨迹和基于卫星的火灾计数进一步揭示了它们在印度恒河平原和印度南部的起源。NO3-浓度与nss单键Ca 2+（粉尘示踪剂）中度相关，表明矿物气溶胶表面的非均匀反应性吸收。尽管浓度很高，但NH 4+（~9.4 ± 7.1 μmol m−2d−1）和WSON（7.4 ± 7.0 μmol m−2d−1）的沉积通量低于NO3−（27 ± 11 μmol m− 2d −1），因为它们具有主要的精细性质（即，与nss-SO 42-有很强的相关性）。我们还限制了在大陆外流期间（11月至4月），WSIN（0.94 Tg yr-1）和WSON（0.08 Tg yr-1）向阿拉伯海的总年大气沉积速率。WSON向阿拉伯海的最大干沉积（0.24 Tg yr−1）是河流补给（0.11 Tg yr−1）的两倍，突出了风成来源的重要性。通过使用Redfield化学计量学，Wyndham沉积（21-73 μmol m−2d−1）可以占阿拉伯海初级生产固定碳的5.3%。
Air-to-sea deposition of water-soluble total nitrogen (WSTN) can influence the primary productivity in the coastal oceans. Here, we assessed the concentrations of aerosol inorganic (WSIN: NH4++ NO3−) and WSTN over the Arabian Sea during winter season (SS379:6–24 December 2018). The mean concentrations of NH4+(109 ± 83 nmol m−3) overwhelm that of NO3−(32 ± 13 nmol m−3) and water-soluble organic nitrogen (WSON: WSTN-WSIN: 86 ± 81 nmol m−3), and contributing to ~50 ± 31% of WSTN mass. Significant linear relationships of WSON with water-soluble organic carbon and NH4+with non-sea-salt (nss)-K+is observed suggesting their common origin from biomass burning and fertilizers. Backward air mass trajectories and satellite-based fire counts further revealed their provenance in the Indo-Gangetic Plain and southern India. The concentration of NO3−moderately correlated with nsssingle bondCa2+(dust tracer), indicating heterogeneous reactive uptake on mineral aerosol surface. Despite high concentrations, the deposition fluxes of NH4+(~9.4 ± 7.1 μmol m−2d−1) and WSON (7.4 ± 7.0 μmol m−2d−1) are lower than NO3−(27 ± 11 μmol m−2d−1) because of their predominant fine nature (i.e.,strong correlation with nss-SO42−). We also constrained the total annual atmospheric deposition rates of WSIN (0.94 Tg yr−1) and WSON (0.08 Tg yr−1) to the Arabian Sea during the continental outflow (November-April). The maximum dry-deposition of WSON to the Arabian Sea (0.24 Tg yr−1) is twice that of the riverine supply (0.11 Tg yr−1), highlighting the significance of aeolian sources. By using Redfield Stoichiometry, the WSTN deposition (21–73 μmol m−2d−1) can account for <5.3% of fixed‑carbon by a primary production in the Arabian Sea.