Marine Humic Substances: Formation Via Vascular Plant Degradation and Biological Availability

木质纤维素是潮间带维管植物的主要成分 以及由此产生的碎屑。这在数量上是很重要的，尽管 沿海湿地中高难降解有机物储存 例如作为盐的沼泽和红树林沼泽。 因此它 是海洋食物网碳和能量的主要来源， 虽然微生物介导的转化为颗粒， 需要溶解的降解产物或微生物生物量 在这种丰富的有机聚合物中的碳可以被 被后生动物利用。 由于木质纤维素被天然海洋微生物降解， 人口，一个显着的部分（高达20-50%）， 总降解产物释放至原液合并液中， 溶解有机碳（DOC）。 重要的是， 木质纤维素衍生的DOC（LC-DOC）符合操作定义 “腐殖”物质。 最近的地球化学研究表明， 来源于以维管植物为主水生植物的腐殖物质 系统的组成不同于腐殖酸来源于 以南极洲为主的远洋系统。 腐殖物质具有 传统上被认为是高度不稳定的， 微生物转化，因此，隐含地，不是一个 为浮游细菌提供燃料的重要碳源和/或能源 二次生产。 这一假设尚未得到直接证实。 在海洋生态系统中受到实验性的挑战， 有证据表明，浮游细菌的生产是以牺牲 DOC腐殖成分在某些环境中具有营养动力学重要性， 系统，并且可用性可能与源（以及 化学成分）的腐殖物质。 这个项目 包括实地和实验室研究，以提高我们的理解 维管植物中溶解的腐殖物质的形成 木质纤维素并确定LC衍生和 支持浮游细菌的天然海洋腐殖物质 生产

Lignocellulose is a major component of intertidal vascular plants and resulting detritus. It is a quantitatively important, although highly refractory, store of organic matter in coastal wetland environments such as salt marshes and mangrove swamps. As such, it represents a major source of carbon and energy to marine food webs, although microbially mediated transformations to particulate and dissolved degradation products or microbial biomass are required before the carbon from this abundant organic polymer can be utilized by metazoans. As lignocellulose is degraded by natural marine microbial populations, a significant fraction (as high as 20-50%) of the total degradation products is released into the bulk pool of dissolved organic carbon (DOC). Importantly, up to half of this lignocellulose-derived DOC (LC-DOC) fits the operational definition of "humic" material. Recent geochemical studies have shown that humic material originating in vascular plant-dominated aquatic systems is compositionally distinct from humics originating in plankton-dominated pelagic systems. Humic material has traditionally been considered to be highly recalcitrant to microbial transformation and thus, implicitly, not to be a significant carbon and/or energy source fueling bacterioplankton secondary production. This assumption has not yet been directly challenged experimentally in marine ecosystems, although there is evidence that bacterioplankton production at the expense of the humic component of DOC can be trophodynamically important in some systems, and that availability may be related to the source (and chemical composition) of the humic substances. This project involves field and laboratory studies to improve our understanding of the formation of dissolved humic substances from vascular plant lignocelluloses and determine the importance of LC-derived and natural marine humics in the support of bacterioplankton production.