Particle fluxes at sediment traps AU9701, south of Australia

Sediment trap moorings were deployed from September 21, 1997 through February 21, 1998 at three locations south of Australia along 140°E: at -47°S in the central Subantarctic Zone (SAZ) with traps at 1060, 2050, and 3850 m depth, at -51°S in the Subantarctic Front with one trap at 3080 m, and at -54°S in the Polar Frontal Zone (PFZ) with traps at 830 and 1580 m. Particle fluxes were high at all the sites (18-32 g/m**2/yr total mass and 0.5-1.4 g organic carbon/m**2/yr at -1000 m, assuming minimal flux outside the sampled summer period). These values are similar to other Southern Ocean results and to the median estimated for the global ocean by Lampitt and Antia [1997], and emphasize that the Southern Ocean exports considerable carbon to the deep sea despite its 'high-nutrient, low chlorophyll' characteristics. The SAZ site was dominated by carbonate (>50% of total mass) and the PFZ site by biogenic silica (>50% of total mass). Both sites exhibited high export in spring and late summer, with an intervening low flux period in December. For the 153 day collection period, particulate organic carbon export was somewhat higher in all the traps in the SAZ (range 0.57-0.84 gC/m**2) than in the PFZ (range 0.31-0.53), with an intermediate value observed at the SAF (0.60). The fraction of surface organic carbon export (estimated from seasonal nutrient depletion, Lourey and Trull [2001]) reaching 1000 m was indistinguishable in the SAZ and PFZ, despite different algal communities.

1997年9月21日至1998年2月21日，研究团队在澳大利亚以南沿东经140°的三个站位部署了沉积物捕集器锚系（sediment trap moorings）：分别为南纬47°的亚南极带（Subantarctic Zone, SAZ）中部站位，该站位布设了水深1060 m、2050 m及3850 m的沉积物捕集器；南纬51°的亚极锋（Subantarctic Front）站位，仅布设了水深3080 m的捕集器；以及南纬54°的极锋带（Polar Frontal Zone, PFZ）站位，布设了水深830 m及1580 m的沉积物捕集器。所有站位的颗粒物通量均处于较高水平：假设采样时段为夏季且采样时段外的通量可忽略不计，1000 m水深处总质量通量为18~32 g/m²/yr，有机碳通量为0.5~1.4 g/m²/yr。该通量数值与南大洋其他研究结果相近，也与Lampitt与Antia [1997]估算的全球海洋有机碳通量中位数相符，这表明尽管南大洋具有“高营养盐低叶绿素”的特征，其仍向深海输出了大量碳。亚南极带站位的颗粒物以碳酸盐为主（占总质量的50%以上），极锋带站位则以生源硅（biogenic silica）为主（占总质量的50%以上）。两个站位均在春季和夏末表现出较高的输出通量，而在12月出现通量低谷期。在153天的采样周期内，亚南极带所有捕集器的颗粒有机碳输出量（范围0.57~0.84 gC/m²）略高于极锋带（范围0.31~0.53 gC/m²），亚极锋站位的对应数值处于中间水平（0.60 gC/m²）。根据Lourey与Trull [2001]通过季节性营养盐消耗估算的结果，尽管两个区域的藻类群落存在差异，但抵达1000 m水深的表层有机碳输出占比在亚南极带与极锋带之间并无显著差异。