Latitudinal δ13Corg variations in sinking matter and sediments from the South Atlantic:: effects of anthropogenic CO2 and implications for paleo-PCO2 reconstructions
Latitudinal δ13Corg variations in sinking matter and sediments from the South Atlantic:: effects of anthropogenic CO2 and implications for paleo-PCO2 reconstructions
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DOI：
10.1016/s0924-7963(98)00059-1
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发表时间：
1998-11-01
影响因子：
2.8
通讯作者：
Wefer, G
中科院分区：
文献类型：
--
作者：
Fischer, G;Müller, P;Wefer, G
对南大西洋浮游生物、沉降颗粒和表层沉积物的δ（13）C（org）的纵向变化进行了汇编，并与文献中的表层沃茨[CO2（aq）]值进行了比较。我们观察到的沉积物三角洲（13）C数据在一个给定的纬度相比，浮游生物值，更敏感地记录季节性变化的变化。在季节性较低的热带-亚热带大西洋，我们测量到沉积物三角洲（13）C的纬度变化相对较小（-18.5至-22.5ppm）。相反，在南纬40度以南发现了同位素值和[CO2（aq）]的陡梯度。南纬60度，沉积物三角洲（13）C值在千分之-23和-26.5之间，对应于一般较高的[CO2（aq）]值。与下沉物质相比，热带-亚热带大西洋的表层沉积物一般重0.5- 3.2ppm，南大洋重3.0- 4.6ppm;它们也比南大洋新鲜沉积的植物碎屑重3.2ppm。这些差异可能至少部分归因于人为PCO 2增加，导致南大洋的影响增强，原因是CO2溶解度增加。我们估计，与现今的测量值相比，来自沉积物三角洲（13）C（org）的工业化前[CO2（aq）]在温暖的沃茨中低1-2 μ mol l（-1），在寒冷的沃茨中高达8 μ mol l（-1）。我们发现，表层沉积物的同位素值通常与表层水[CO2（aq）]（工业化前）相关，导致与浮游生物数据的关系非常相似[Rau，G.H.，1994.沉积有机三角洲（13）C的变化作为海洋和大气CO2浓度过去变化的代理。在：Zahn，R.，彼得森，TF，卡明斯基，文学硕士，拉贝里湖（编），冰川海洋中的碳循环，北约亚洲科学研究所系列，全球环境变化，第17卷]。然而，对沉积物三角洲（13）C（org）的过去[CO2（aq）]的估计可能有很大的不确定性，特别是在南大洋。在这里，我们的数据显示出最弱的相关性，这可能是由于增长率和生产率变化的影响，特别是在前沿地区。
Latitudinal variations of delta(13)C(org) of plankton, sinking particles and surface sediments of the southern Atlantic Ocean have been compiled and compared to literature-derived [CO2 (aq)] values in surface waters. We observed less variability of the sediment-delta(13)C data at a given latitude compared to the plankton values which more sensitively record seasonal changes. In the tropical-subtropical Atlantic with low seasonality, we measured a relatively small latitudinal variation (-18.5 to -22.5 parts per thousand) of the sediment-delta(13)C. In contrast, a steep gradient of both isotope values and [CO2 (aq)] was found south of 40 degrees S. South of 60 degrees S, the sediment-delta(13)C values were between -23 and -26.5 parts per thousand corresponding to generally higher [CO2 (aq)] values. The surface sediments were generally heavier by 0.5-3.2 parts per thousand in the tropical-subtropical Atlantic and 3.0-4.6 parts per thousand in Southern Ocean, respectively, compared to sinking matter; they were also heavier by up to 3.2 parts per thousand than freshly sedimented phytodetritus sampled in the Southern Ocean. These differences may at least be partly attributed to the anthropogenic PCO2 increase leading to an enhanced effect in the Southern Ocean due to increasing CO, solubility. We estimated the preindustrial [CO2 (aq)] from sediment-delta(13)C(org) to be lower by 1-2 mu mol l(-1) in warm waters and up to 8 mu mol l(-1) in cold waters compared to present day measurements. We found that the isotope values of the surface sediments were generally linked to surface water [CO2 (aq)] (preindustrial), resulting in a relationship rather similar to that derived from plankton data [Rau, G.H., 1994. Variations in sedimentary organic delta(13)C as a proxy for past changes in ocean and atmospheric CO2 concentrations. In: Zahn, R., Pedersen, T.F., Kaminski, M.A., Labeyrie, L. (Eds.), Carbon Cycling in the Glacial Ocean, NATO Asi Series, Global Environmental Change, Vol. 17]. However, estimations of past [CO2 (aq)] from sediment-delta(13)C(org) may have a large uncertainty especially in the Southern Ocean. Here, our data show the weakest correlation, probably due to effects of changing growth rates and productivity, in particular at the frontal zones.