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首页> 外文期刊>Marine Chemistry >Sources, Pathways And Sinks Of Particulate Organic Matter In Hudson Bay: Evidence From Lignin Distributions
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Sources, Pathways And Sinks Of Particulate Organic Matter In Hudson Bay: Evidence From Lignin Distributions

机译：哈德逊湾颗粒有机物的来源，途径和汇：来自木质素分布的证据

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摘要

Hudson Bay is a large, estuarine, shelf-like sea at the southern margin of the Arctic, where changes in seasonal ice cover and river discharge appear already to be underway. Here we present lignin data for dated sediments from eleven box cores and evaluate sources of terrigenous carbon, transport pathways, and whether terrigenous organic matter has been influenced by recent environmental change. Lignin yields (0.04 to 1.46 mg/100 mg organic carbon) decreased from the margin to the interior and from south to north, broadly reflecting the distribution of river inputs. Lignin compositional patterns indicated distinct regional sources with boreal forest (woody gymnosperm) vegetation an important source in the south, vs. tundra (non-woody angiosperm) in the north. Lignin patterns suggest redistribution of a fine-grained, mineral-associated fraction of the southern-derived terrigenous carbon to the northeast part of the Bay and ultimately into west Hudson Strait with the Bay's cyclonic coastal circulation. A small component of the carbon makes it to the central basins of Hudson Bay but most of the terrigenous organic material in that area appears to derive from resuspension of older, isostatically-rebounding coastal and inner shelf deposits. Most modern plant debris appears to be retained near river mouths due to hydrodynamic sorting, with the exception of the southwest inner shelf, where these materials extend >30 km from shore. Temporal changes in the composition of terrigenous organic carbon recorded in most of the southern Hudson Bay cores perhaps reflect increases in erosion and cross-shelf transport from coastal deposits, possibly mediated by change in ice climate. In contrast, temporal changes in the northwest may relate to changes in the supply of modern plant debris under recent warmer conditions. On the western shelf, changes may relate to ice climate and the distribution of northern coastal water and/or changes in the delivery of materials by the Churchill River due to water diversion. Although the cores show evidence of change related to the ice climate, there is little evidence that ice itself transports terrigenous organic carbon within the system.
机译：哈德逊湾是北极南部边缘的一个大的，河口状，架子状的海洋，季节性冰盖和河流流量的变化似乎已经在进行。在这里，我们提供了来自11个箱芯的过时沉积物的木质素数据，并评估了陆源碳的来源，运输途径以及陆源有机质是否受到近期环境变化的影响。木质素的产量（0.04至1.46 mg / 100 mg有机碳）从边缘到内部以及从南到北下降，这在很大程度上反映了河流投入的分布。木质素的组成模式表明了不同的区域性来源，其中北方的北方森林是北方森林（裸子植物）的重要植物，而北方的苔原（非木质被子植物）则是重要的植物。木质素模式表明，南部衍生的陆源碳的细粒，矿物相关部分重新分布到海湾的东北部，并随着海湾的气旋沿海环流最终分布到哈德逊海峡西部。碳的一小部分使其进入哈德逊湾的中部盆地，但该地区的大部分陆源有机物质似乎都来自较老的，等静回弹的沿海和内陆架沉积物的再悬浮。由于流体动力分类，大多数现代植物残渣似乎保留在河口附近，除了西南内陆架外，这些内陆架离海岸的距离超过30公里。哈德逊湾南部大多数核心地区记录的陆源有机碳成分的时间变化可能反映了沿海沉积物的侵蚀和跨架运输的增加，这可能是由于冰雪气候的变化所介导的。相反，西北地区的时间变化可能与最近变暖条件下现代植物碎屑的供应变化有关。在西部大陆架上，变化可能与冰的气候和北部沿海水的分布和/或由于调水导致丘吉尔河的物质输送变化有关。尽管岩心显示出与冰层气候有关的变化证据，但几乎没有证据表明冰层本身在系统中运输了陆源有机碳。

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