Utilizing Po-210 deficit to constrain particle dynamics in mesopelagic water, western South China Sea
Utilizing Po-210 deficit to constrain particle dynamics in mesopelagic water, western South China Sea
复制标题
利用 Po-210 赤字限制南海西部中层水中的颗粒动力学
DOI：
10.1002/2017gc006899
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发表时间：
2017
影响因子：
3.5
通讯作者：
Zheng Minfang
中科院分区：
文献类型：
--
作者：
Ma Haoyang;Yang Weifeng;Zhang Lihao;Zhang Run;Chen Min;Qiu Yusheng;Zheng Minfang
210po‐210Pb对越来越多地被用作量化从光带输出的有机碳的代理。然而，对中远洋水体中210po和210pb的不平衡研究甚少。在这里，我们发现在中国南海（SCS）的中上层水域（200-1000米），相对于210pb， 210po异常缺乏。中上层的总颗粒物（TPM）比透光层增加了32%。总210po /210Pb比值在0.41 ~ 0.98之间变化，平均值为0.72±0.19，对中远洋水体中210po的去除效果较好。坡面站点的210po和210pb含量平均分别增加了23%和32%。这些结果表明，210 - po缺陷可能是通过底栖网状层的横向运输造成的。基于210po的缺乏，估计210po颗粒的停留时间为0.11 ~ 0.25年（平均0.17±0.07年），使重悬沉积物在较长时间内分散。210po的输出通量在68 ~ 121 dpm m−2d−1之间变化，平均为96±27 dpm m−2d−1，是光区输出通量的6倍。利用210 po亏缺，从中上层出口的TPM通量在4.19 ~ 10.20 g m−2d−1之间变化，揭示了从大陆架到南海盆地的大量颗粒。该研究表明，210po‐210Pb可能是跟踪中远洋水体中颗粒循环的有效示踪剂。
The210Po‐210Pb pair is increasingly used as a proxy of quantifying organic carbon export from the euphotic zone. However, disequilibria between210Po and210Pb in mesopelagic water have been poorly studied. Here we present unusual deficiencies of210Po with respect to210Pb in mesopelagic water (200–1000 m) in the South China Sea (SCS). The total particulate matter (TPM) increased by up to 32% in the mesopelagic layer comparing with the euphotic zone. The total210Po/210Pb ratio varied from 0.41 to 0.98 with an average of 0.72 ± 0.19, showing an enhanced removal of210Po in mesopelagic water. On average, particulate210Po and210Pb increased by 23% and 32% at the slope stations, respectively. These results indicated that the210Po deficits result from lateral transport, probably via benthic nepheloid layer. Based on the deficiency of210Po, the residence times of particulate210Po were estimated to range from 0.11 to 0.25 year (avg. 0.17 ± 0.07 year), allowing resuspended sediment to disperse over a long range. The export fluxes of210Po varied from 68 to 121 dpm m−2d−1with an average of 96 ± 27 dpm m−2d−1, which was 6 times that out of the euphotic zone. Using the210Po deficits, the export fluxes of TPM out of the mesopelagic layer were quantified to vary from 4.19 to 10.20 g m−2d−1, revealing a large amount of particles from the shelf to the SCS basin. This study suggests that210Po‐210Pb could be an effective tracer of tracking particle cycling in mesopelagic water.