Insights into estuarine benthic dissolved organic carbon (DOC) dynamics using δ13C-DOC values, phospholipid fatty acids and dissolved organic nutrient fluxes
Insights into estuarine benthic dissolved organic carbon (DOC) dynamics using δ13C-DOC values, phospholipid fatty acids and dissolved organic nutrient fluxes
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DOI：
10.1016/j.gca.2011.01.007
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发表时间：
2011-04
影响因子：
5
通讯作者：
D. Maher;B. Eyre
中科院分区：
文献类型：
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作者：
D. Maher;B. Eyre
通过测定河口生产性沉积物中溶解有机碳（DOC）通量、DOC同位素比值、营养盐通量、磷脂脂肪酸浓度和碳同位素比值，探讨DOC的底栖-远洋耦合机制。DOC在黑暗中吸收，在所有网站的光流出。DOC吸收速率与底栖呼吸（暗O2吸收）和流出耦合到沉积物的营养状态（生产呼吸比）。最高的吸收和流出率，观察到在两个高营养浓度的网站。水体溶解性有机物（DOM）的DOC：DON比值在黑暗时减小，在光照时增大，表明富碳溶解性有机物优先吸收和释放。计算的DOC的底栖生物所采取的碳同位素比值是显着超过散装水柱DOC池耗尽，建议优先吸收选定的组件的水柱DOC池。一般来说，在光照下释放的DOC的同位素比值比在黑暗中，这表明底栖生物具有显着改变河口DOC库的潜力。吸收和流出耦合到呼吸和藻类放牧/矿化，因此增加营养负荷可能会改变河口DOC池的组成，通过底栖DOC通量的大小变化。生物（DOC生产和消费的昼夜变化）和非生物过程（絮凝）的组合似乎是驱动所观察到的底栖DOC动态的研究地点。这项研究是第一个测量的水柱DOC库中的碳同位素变化，由于底栖生物的过程，并表明，底栖生物可以改变河口DOC库通过在DOC的吸收和流出的昼夜差异。
Benthic dissolved organic carbon (DOC) flux rates and changes in DOC isotope ratios, along with nutrient fluxes, phospholipid fatty acids concentration and carbon isotope ratios were measured in productive estuarine sediments over a diel cycle to determine the mechanisms driving benthic–pelagic coupling of DOC. There was uptake of DOC during the dark and efflux during the light at all sites. DOC uptake rates were related to benthic respiration (dark O2uptake) and effluxes were coupled to the trophic status (ratio of production to respiration) of the sediments. Highest uptake and efflux rates were observed at two high nutrient concentration sites. The DOC:DON ratio of water column dissolved organic matter (DOM) decreased during the dark and increased during the light indicating preferential uptake and release of carbon rich dissolved organic matter. The calculated carbon isotope ratio of the DOC taken up by the benthos was significantly more depleted than the bulk water column DOC pool, suggesting preferential uptake of selected components of the water column DOC pool. Generally the isotope ratio of the DOC released during the light was more enriched than that taken up during the dark, which suggests that the benthos has the potential to significantly alter the estuarine DOC pool. Uptake and efflux were coupled to respiration and algal grazing/mineralization, therefore increased nutrient loading may shift the composition of the estuarine DOC pool through changes in the magnitude of benthic DOC fluxes. A combination of biological (diel shifts in DOC production and consumption) and abiotic processes (flocculation) appear to be driving the observed benthic DOC dynamics at the study sites. This study was the first to measure carbon isotopic changes in the water column DOC pool due to benthic processes, and shows that the benthos can alter the estuarine DOC pool through diel differences in DOC uptake and efflux.