Controls on mesopelagic particle fluxes in the Sub-Antarctic and Polar Frontal Zones in the Southern Ocean south of Australia in summer-Perspectives from free-drifting sediment traps
Controls on mesopelagic particle fluxes in the Sub-Antarctic and Polar Frontal Zones in the Southern Ocean south of Australia in summer-Perspectives from free-drifting sediment traps
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DOI：
10.1016/j.dsr2.2011.05.025
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发表时间：
2011-11-01
影响因子：
3
通讯作者：
Bray, Stephen G.
中科院分区：
文献类型：
--
作者：
Ebersbach, Friederike;Trull, Thomas W.;Bray, Stephen G.
SAZ-Sense项目研究了南半球夏季南大洋碳输出的生态系统控制（2007年1月至2月）在三个地点：P1在低生物量的亚热带地区（SAZ）西部的塔斯马尼亚，P3在一个地区的生物量升高的SAZ东部的塔斯马尼亚燃料增加铁供应，和P2在高营养/低叶绿素（HNLC）极地锋面区（PFZ）沃茨南部的P1和P3。沉降颗粒的收集使用（i）一个圆柱形的时间序列（PPS 3/3）陷阱的散装地球化学通量，（ii）锯齿状旋转球（IRS）陷阱操作为原位沉降柱，以确定跨沉降率分数的通量分布，以及（iii）填充有聚丙烯酰胺凝胶的圆柱形捕集器，以获得用于图像分析的完整颗粒。（PPS 3/3陷阱）在P1时最高，P2时较低，P3时最低（分别为3.3 +/- 1.8、2.1 +/- 0.9和0.9 +/- 0.4 mmol m（-2）d（-1））。SAZ中的生物硅（BSi）通量非常低（P1和P3分别为0.2 +/- 0.2和0.02 +/- 0.005 mmol m（-2）d（-1）），PFZ中的生物硅通量要高得多（P2为2.3 +/- 0.5 mmol m（-2）d（-1））。因此，高生物量位点P3没有表现出相应的高POC或BSi通量。用IRS捕集器分离沉降率组分（在170和320 m深度）仅在PFZ站点P2处成功，在那里观察到通量的相对均匀分布，其中类似于1/3的POC下沉快于100 m d（-1），1/3下沉慢于10 m d（-1）。（在140、190、240和290米深度）使我们能够识别5种不同的类别：绒毛状聚集体（低密度多孔或无定形聚集体）、粪便聚集体（由不同类型的颗粒组成的密度更大的聚集体）、圆柱形和卵形粪便颗粒以及分离的植物细胞（链和单细胞）。粪便聚集体占主导地位的通量在所有网站，并在P1的大小相比，P3。PFZ网站P2有很大的不同，从两个SAZ网站在具有更高的丰度的硅藻和相对较小尺寸的粪便聚集体。总体而言，颗粒图像表明，放牧是一个重要的影响，在所有三个网站的垂直出口，大的聚集体形成和直接硅藻出口的程度的差异进一步影响网站之间的差异。(C)2011爱思唯尔有限公司保留所有权利。
The SAZ-Sense project examined ecosystem controls on Southern Ocean carbon export during austral summer (January-February 2007) at three locations: P1 in the low biomass Subantarctic Zone (SAZ) west of Tasmania, P3 in a region of elevated biomass in the SAZ east of Tasmania fuelled by enhanced iron supply, and P2 in High-Nutrient/Low Chlorophyll (HNLC) Polar Frontal Zone (PFZ) waters south of P1 and P3. Sinking particles were collected using (i) a cylindrical time-series (PPS3/3) trap for bulk geochemical fluxes, (ii) indented rotating sphere (IRS) traps operated as in-situ settling columns to determine the flux distribution across sinking-rate fractions, and (iii) cylindrical traps filled with polyacrylamide gels to obtain intact particles for image analysis.Particulate organic carbon (POC) flux at 150 m (PPS3/3 trap) was highest at P1, lower at P2, and lowest at P3 (3.3 +/- 1.8, 2.1 +/- 0.9, and 0.9 +/- 0.4 mmol m(-2) d(-1), respectively). Biogenic silica (BSi) flux was very low in the SAZ (0.2 +/- 0.2 and 0.02 +/- 0.005 mmol m(-2) d(-1) at P1 and P3, respectively) and much higher in the PFZ (2.3 +/- 0.5 mmol m(-2) d(-1) at P2). Hence, the high biomass site P3 did not exhibit a correspondingly high flux of either POC or BSi. Separation of sinking-rate fractions with the IRS traps (at 170 and 320 m depth) was only successful at the PFZ site P2, where a relatively uniform distribution of flux was observed with similar to 1/3 of the POC sinking faster than 100 m d(-1) and 1/3 sinking slower than 10 m d(-1).Analysis of thousands of particles collected with the gel traps (at 140, 190, 240, and 290 m depth) enabled us to identify 5 different categories: fluff-aggregates (low-density porous or amorphous aggregates), faecal-aggregates (denser aggregates composed of different types of particles), cylindrical and ovoid faecal pellets, and isolated phyto-cells (chains and single cells). Faecal-aggregates dominated the flux at all sites, and were larger in size at P1 in comparison to P3. The PFZ site P2 differed strongly from both SAZ sites in having a much higher abundance of diatoms and relatively small-sized faecal-aggregates. Overall, the particle images suggest that grazing was an important influence on vertical export at all three sites, with differences in the extents of large aggregate formation and direct diatom export further influencing the differences among the sites. (C) 2011 Elsevier Ltd. All rights reserved.