FACTORS INFLUENCING ORGANIC-CARBON PRESERVATION IN MARINE-SEDIMENTS
FACTORS INFLUENCING ORGANIC-CARBON PRESERVATION IN MARINE-SEDIMENTS
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DOI：
10.1016/0009-2541(94)90061-2
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发表时间：
1994-06-01
期刊：
影响因子：
3.9
通讯作者：
CANFIELD, DE
中科院分区：
文献类型：
--
作者：
CANFIELD, DE
逃脱分解的有机物被埋藏并保存在海洋沉积物中，关于其数量是否取决于底层水O2浓度存在很大争议。一个小组认为，分解是更有效的O2，因此，有机碳将优先氧化在它的存在，并保存在它的缺席。另一组认为，有机物分解的动力学在O2存在和不存在的情况下是相似的，并且O2对保存没有影响。一份关于碳保存的汇编显示，根据沉积的情况，两组人都是对的。在沉积速率高的地方，例如靠近大陆边缘的地方，在保存方面的差别不大，因为底层水中的氧含量不同。重要的是，这些沉积物中的大多数碳通过厌氧途径分解，而不管底层水O2。因此，几乎没有影响的底层水O2的保存，事实上，预计。随着沉积速率的下降，沉积在含氧底层水中的沉积物逐渐变得更好氧，而富氧沉积物则保持厌氧。在这种情况下，好氧和厌氧分解的相对效率可能会影响保存。事实上，在低氧和缺氧环境中观察到增强的保存。为了详细探讨这种增强碳保存的因素，需氧和厌氧过程的生物化学方面进行了审查。对保存的其他潜在影响也进行了探讨。最后，提出了一个新的有机碳分解模型--“伪G”模型。该模型将难降解有机物的降解与沉积物的总体代谢活动相结合，并由于生物扰动将不稳定和难降解有机物混合在一起而导致碳保存的后果。
The organic matter that escapes decomposition is buried and preserved in marine sediments, with much debate as to whether the amount depends on bottom-water O2 concentration. One group argues that decomposition is more efficient with O2, and hence, organic carbon will be preferentially oxidized in its presence, and preserved in its absence. Another group argues that the kinetics of organic matter decomposition are similar in the presence and absence of O2, and there should be no influence of O2 on preservation. A compilation of carbon preservation shows that both groups are right, depending on the circumstances of deposition. At high rates of deposition, such as near continental margins, little difference in preservation is found with varying bottom-water O2. It is important that most carbon in these sediments decomposes by anaerobic pathways regardless of bottom-water O2. Hence, little influence of bottom-water O2 on preservation would, in fact, be expected. As sedimentation rate drops, sediments deposited under oxygenated bottom water become progressively more aerobic, while euxinic sediments remain anaerobic. Under these circumstances, the relative efficiencies of aerobic and anaerobic decomposition could affect preservation. Indeed, enhanced preservation is observed in low-O2 and euxinic environments. To explore in detail the factors contributing to this enhanced carbon preservation, aspects of the biochemistries of the aerobic and anaerobic process are reviewed. Other potential influences on preservation are also explored. Finally, a new model for organic carbon decomposition, the ''pseudo-G'' model, is developed. This model couples the degradation of refractory organic matter to the overall metabolic activity of the sediment, and has consequences for carbon preservation due to the mixing together of labile and refractory organic matter by bioturbation.