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首页> 外文期刊>Marine Chemistry >Use of lipids and their degradation products as biomarkers for carbon cycling in the northwestern Mediterranean Sea
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Use of lipids and their degradation products as biomarkers for carbon cycling in the northwestern Mediterranean Sea

机译：使用脂质及其降解产物作为地中海西北部碳循环的生物标记

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Changes in phytoplankton composition and degradation of particulate organic matter (POM) in the northwestern Mediterranean Sea were studied using time-series sediment trap samples collected during the spring of 2003 at the DYFAMED station. Upid biomarkers (pigments, fatty acids, sterols, acyclic isoprenoids, alkenones and n-alkanols) were used to identify the main contributors to the POM produced during two phytoplankton blooms, while the effects of photooxidation, autoxidation and biodegradation were differentiated using characteristic lipid degradation products. Traps collected material corresponding to pre-bloom, bloom and post-bloom periods. Pigment analyses in the integrated (0-200 m) water column samples indicated that diatoms dominated the initial stages of the bloom event, with smaller amounts of haptophytes and pelagophytes. During the second part of bloom event there was a switch to haptophyte dominance with significant contributions from diatoms and pelagophytes, and an increased contribution from cryptophytes. Fatty acid distributions in the trap samples reflected contributions from marine bacteria, phytoplankton and zooplankton. Photooxidation and autoxidation products of monounsaturated oleic, cis-vaccenic and palmitoleic acids were detected along with photooxidation products from the chlorophyll side-chain. The relatively good correlation between the variation of U_(37)~K' index and specific phytol autoxidation product percentage allowed us to attribute the alterations of U_(37)~K' observed during the pre-bloom period and in the deeper traps to the involvement of selective autoxidative degradation processes. A variety of sterol oxidation products formed by biohydrogenation, autoxidation and photooxidation were detected. Sterol degradation products appeared to be less suited than oxidation products of monounsaturated fatty acids for the precise monitoring of the degradation state of POM, but their stable functionalized cyclic structure constitutes a useful tool to estimate the part played by biotic and abiotic processes. In these waters, biotic degradation generally predominates, but abiotic degradation is not negligible and, as expected, the extent of biotic degradation increases with depth. To obtain a more complete picture of POM degradation, the use of a pool of lipid degradation products (i.e. from unsaturated fatty acids, the phytyl side-chain and sterols) should be employed.
机译：利用2003年春季在DYFAMED站收集的时间序列沉积物捕集阱样品，研究了地中海西北部浮游植物组成的变化和颗粒有机物（POM）的降解。使用Upid生物标志物（色素，脂肪酸，固醇，无环类异戊二烯，烯酮和正烷醇）来鉴定两次浮游植物开花期间产生的POM的主要贡献者，而光氧化，自氧化和生物降解的作用则通过独特的脂质降解来区分产品。陷阱收集的花朵对应于开花前，开花和开花后时期。在集成的（0-200 m）水柱样品中进行的颜料分析表明，硅藻在水华事件的初期占主导地位，而附生植物和聚伞植物的数量较少。在绽放事件的第二部分中，硅藻和pelagophytes显着贡献，而隐生植物的贡献增加，切换到haptophyte优势。捕集阱样品中的脂肪酸分布反映了海洋细菌，浮游植物和浮游动物的贡献。检测到单不饱和油酸，顺式-癸酸和棕榈油酸的光氧化和自氧化产物以及叶绿素侧链的光氧化产物。 U_（37）〜K'指数的变化与特定植物醇自氧化产物百分比之间的相对良好相关性，使我们可以将在开花前期和更深陷阱中观测到的U_（37）〜K'的变化归因于参与选择性自氧化降解过程。检测了通过生物氢化，自氧化和光氧化形成的各种甾醇氧化产物。对于精确监测POM的降解状态，甾醇降解产物似乎不如单不饱和脂肪酸的氧化产物合适，但是它们稳定的官能化环状结构构成了评估生物和非生物过程所起的作用的有用工具。在这些水域中，生物降解通常占主导地位，但非生物降解是不可忽略的，并且正如预期的那样，生物降解的程度随深度的增加而增加。为了获得更完整的POM降解图，应使用一系列脂质降解产物（即来自不饱和脂肪酸，植酸侧链和固醇的脂质降解产物）。

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