Western Pacific atmospheric nutrient deposition fluxes, their impact on surface ocean productivity
Western Pacific atmospheric nutrient deposition fluxes, their impact on surface ocean productivity
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DOI：
10.1002/2013gb004794
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发表时间：
2014-07
影响因子：
5.2
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中科院分区：
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大量营养素和微量营养素的大气沉积在推动初级生产力方面发挥着重要作用，特别是在低纬度海洋中。我们报告了在西太平洋从~25°N到20°S的五次船基采样活动的气溶胶主要离子测量结果，并将结果与在同一实验室收集和分析气溶胶的大西洋纬向断面（~50°N到50°S）的结果进行了比较，允许完全不可比性。我们讨论了气溶胶中主要营养物质（氮（N），磷（P）和铁（Fe））的来源及其化学计量。两个盆地都有明显的南北梯度，北方半球受陆地尘埃源和人为排放的影响更大，北大西洋的影响明显大于北太平洋。我们估计了这些营养盐的大气供应率和大气沉降对热带西太平洋的潜在影响。我们的研究结果表明，相对于居民浮游植物的需求，大气沉降是缺乏磷。这些研究结果表明，大气供应的N，Fe和P提高初级生产力利用一些残留的过量磷（P*）在表面沃茨，以弥补气溶胶P缺乏。区域初级生产力的进一步提高，通过刺激固氮的燃料由大气残留的铁和P*。我们的化学计量计算表明，0.1 µmol L−1的P* 可以抵消大气供应中多个月的P不足。这项研究表明，大气沉降可能维持约10%的初级生产力在热带西太平洋。
The atmospheric deposition of both macronutrients and micronutrients plays an important role in driving primary productivity, particularly in the low‐latitude ocean. We report aerosol major ion measurements for five ship‐based sampling campaigns in the western Pacific from ~25°N to 20°S and compare the results with those from Atlantic meridional transects (~50°N to 50°S) with aerosols collected and analyzed in the same laboratory, allowing full incomparability. We discuss sources of the main nutrient species (nitrogen (N), phosphorus (P), and iron (Fe)) in the aerosols and their stoichiometry. Striking north–south gradients are evident over both basins with the Northern Hemisphere more impacted by terrestrial dust sources and anthropogenic emissions and the North Atlantic apparently more impacted than the North Pacific. We estimate the atmospheric supply rates of these nutrients and the potential impact of the atmospheric deposition on the tropical western Pacific. Our results suggest that the atmospheric deposition is P deficient relative to the needs of the resident phytoplankton. These findings suggest that atmospheric supply of N, Fe, and P increases primary productivity utilizing some of the residual excess phosphorus (P*) in the surface waters to compensate for aerosol P deficiency. Regional primary productivity is further enhanced via the stimulation of nitrogen fixation fuelled by the residual atmospheric iron and P*. Our stoichiometric calculations reveal that a P* of 0.1 µmol L−1 can offset the P deficiency in atmospheric supply for many months. This study suggests that atmospheric deposition may sustain ~10% of primary production in both the western tropical Pacific.