Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment.
Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment.
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DOI：
10.5194/bg-7-3769-2010
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发表时间：
2010-11
期刊：
影响因子：
4.9
通讯作者：
T. Wagener;C. Guieu;N. Leblond
中科院分区：
文献类型：
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作者：
T. Wagener;C. Guieu;N. Leblond
抽象的。土壤灰尘沉积被认为是全球和区域范围内公海铁的主要来源。然而，尘埃沉积后控制海洋表层铁的形态和循环的过程却很少有记录，这主要是由于调查现场自然尘埃事件的后勤困难。 DUNE 项目（低营养低叶绿素生态系统中的 DUst 实验）框架内清洁中生态系统的发展是在一次灰尘沉积事件的未探索规模上研究这些过程的独特机会。在 DUNE-1-P 中宇宙播种实验期间，在模拟 10 g m−2 湿沉降的人工粉尘播种后 8 天内，对铁库存（水柱中的溶解浓度和颗粒浓度）和通量（沉积物捕集器中颗粒铁的输出）进行了跟踪。在中宇宙表面添加灰尘后，0-10 m 水柱中溶解铁 [dFe] 浓度立即下降。这种减少可能是由于 dFe 对沉降灰尘颗粒和矿物有机骨料的清除作用。溶解铁对粉尘颗粒的清除率平均为 0.37 ± 0.12 nmol mg−1。与中生态实验并行进行的批量溶解实验表明，与对照条件相比，施有粉尘的水中的粉尘铁溶解能力增加（高达 600%）。这项研究提供了灰尘沉积对海洋表面生物地球化学复杂且意想不到的影响的证据：（1）大量灰尘沉积事件可能是海洋表面溶解铁的汇，（2）连续的灰尘沉积事件可能会在海洋表面引起不同的生物地球化学反应。
Abstract. Soil dust deposition is recognized as a major source of iron to the open ocean at global and regional scales. However, the processes that control the speciation and cycle of iron in the surface ocean after dust deposition are poorly documented mainly due to the logistical difficulties to investigate in-situ, natural dust events. The development of clean mesocosms in the frame of the DUNE project (a DUst experiment in a low Nutrient low chlorophyll Ecosystem) was a unique opportunity to investigate these processes at the unexplored scale of one dust deposition event. During the DUNE-1-P mesocosm seeding experiment, iron stocks (dissolved and particulate concentrations in the water column) and fluxes (export of particulate iron in sediment traps) were followed during 8 days after an artificial dust seeding mimicking a wet deposition of 10 g m−2. The addition of dust at the surface of the mesocosms was immediately followed by a decrease of dissolved iron [dFe] concentration in the 0–10 m water column. This decrease was likely due to dFe scavenging on settling dust particles and mineral organic aggregates. The scavenging ratio of dissolved iron on dust particles averaged 0.37 ± 0.12 nmol mg−1. Batch dissolution experiments conducted in parallel to the mesocosm experiment showed a increase (up to 600%) in dust iron dissolution capacity in dust-fertilized waters compared to control conditions. This study gives evidences of complex and unexpected effects of dust deposition on surface ocean biogeochemistry: (1) large dust deposition events may be a sink for surface ocean dissolved iron and (2) successive dust deposition events may induce different biogeochemical responses in the surface ocean.