Phosphorus geochemistry of equatorial Pacific sediments
Phosphorus geochemistry of equatorial Pacific sediments
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DOI：
10.1016/0016-7037(96)00042-7
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发表时间：
1996-05-01
影响因子：
5
通讯作者：
Delaney, ML
中科院分区：
文献类型：
--
作者：
Filippelli, GM;Delaney, ML
了解磷（P）的地球化学和埋藏在海洋沉积物中是重要的，因为P调节海洋生产力的长期时间尺度上的作用。在过去的5300万年里，我们调查了赤道太平洋七个地点的磷地球化学，利用连续提取技术阐明沉积物中的磷组成和磷成岩作用。这些沉积物中的主要含磷组分是自生磷（占总磷的61-86%），相对优势依次为铁结合磷（7-17%）、有机磷（3-12%）、吸附磷（2-9%）和碎屑磷（0-1%）。P组分组成存在明显的时间趋势。有机磷在东太平洋较年轻的沉积物中迅速减少（这是在较年轻的间隔中具有高样品分辨率的唯一地点），从0-1 Ma间隔中的2.3 μ mol P/g沉积物的平均浓度到5-6 Ma间隔中的0.4 μ mol/g。在同一时间间隔内，也观察到铁结合P（从2.1 μ mol P/g至1.1 μ mol P/g）和吸附P（从1.5 μ mol P/g至0.7 μ mol P/g）的减少。这些减少与自生磷的增加相反，（6.0-9.6 μ mol P/g），碎屑P无显著变化（0.1 μ mol P/g）和全P P地球化学的这些时间趋势表明：（1）有机质，P到海底的主要穿梭物，在沉积物中再生，并将相关的P释放到间隙沃茨，（2）在微生物铁还原时，与富铁羟基氧化物相关的P被释放到间隙沃茨中，（3）吸附P随年龄和深度的减少可能表明间隙水P浓度的类似减少，以及（4）碳酸氟磷灰石（CFA），或另一种自生含P相，沉淀由于释放的P从有机质和铁羟基氧化物，并成为一个越来越重要的P汇与年龄和深度。P在各种沉积池之间的重组及其最终并入CFA，已在各种大陆边缘环境中得到承认，但这是第一次在深海沉积物中发现这些过程。这项研究和其他研究的磷积累速率数据表明，全球人类活动前向海洋输入的磷的速率（20 × 10（10）mol P/年）比以前认为的高出约4倍，支持最近的建议，即P在海洋中的停留时间可能短至10，000 - 20，000年。
Understanding phosphorus (P) geochemistry and burial in oceanic sediments is important because of the role of P for modulating oceanic productivity on long timescales. We investigated P geochemistry in seven equatorial Pacific sites over the last 53 m.y., using a sequential extraction technique to elucidate sedimentary P composition and P diagenesis within the sediments. The dominant P-bearing component in these sediments is authigenic P (61-86% of total P), followed in order of relative dominance by iron-bound P (7-17%), organic P (3-12%), adsorbed P (2-9%), and detrital P (0-1%). Clear temporal trends in P component composition exist. Organic P decreases rapidly in younger sediments in the eastern Pacific (the only sites with high sample resolution in the younger intervals), from a mean concentration of 2.3 mu mol P/g sediment in the 0-1 Ma interval to 0.4 mu mol/g in the 5-6 Ma interval. Over this same time interval, decreases are also observed for iron-bound P (from 2.1 to 1.1 mu mol P/g) and adsorbed P (from 1.5 to 0.7 mu mol P/g). These decreases are in contrast to increases in authigenic P (from 6.0-9.6 mu mol P/g) and no significant changes in detrital P (0.1 mu mol P/g) and total P (12 mu mol P/g).These temporal trends in P geochemistry suggest that (1) organic matter, the principal shuttle of P to the seafloor, is regenerated in sediments and releases associated P to interstitial waters, (2)P associated with iron-rich oxyhydroxides is released to interstitial waters upon microbial iron reduction, (3) the decrease in adsorbed P with age and depth probably indicates a similar decrease in interstitial water P concentrations, and (4) carbonate fluorapatite (CFA), or another authigenic P-bearing phase, precipitates due to the release of P from organic matter and iron oxyhydroxides and becomes an increasingly significant P sink with age and depth. The reorganization of P between various sedimentary pools, and its eventual incorporation in CFA, has been recognized in a variety of continental margin environments, but this is the first time these processes have been revealed in deep-sea sediments. Phosphorus accumulation rate data from this study and others indicates that the global pre-anthropogenic input rate of P to the ocean (20 X 10(10) mol P/yr) is about a factor of four times higher than previously thought, supporting recent suggestions that the residence time of P in the oceans may be as short as 10,000-20,000 years.