Biogeochemistry of coastal marine sediments

沿海海洋沉积物的生物地球化学

• 批准号: 124367-2006
• 负责人: Sundby, Bjorn
• 金额: $ 2.46万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=391353
• 关键词: Biogeochemistry; coastal; marine; sediments

The interest in the environmental chemistry of metals stems from the fundamental importance of metals to living organisms and the realization that man's activities have altered the natural cycle of metals. Metals enter the environment via different pathways and are removed by deposition on the sea floor and burial. Before metals are buried so deep that they are removed permanently and become part of the geological record, they participate in chemical and biochemical reactions, mediated by the organisms that inhabit the sedimentary environment. This proposal will examine organism-sediment interactions in sediment where the dominant macro-organisms are either invertebrates or plants. The focus will be on metal-binding organic compounds produced by organisms, and the complexes they form with metal ions. These complexes have different solubility, mobility, availability, and toxicity than uncomplexed metals. Invertebrate organisms construct burrows and galleries, extending the contact between sediment and overlying water, and stimulating the exchange of complexed and uncomplexed metals between sediment and water. Intertidal vascular plants do not influence exchange of metals with the water column, but their hollow roots transport oxygen, which oxidizes reduced sediment. Root also release metal-binding organic acids. The growth and decay of roots produce profound changes in metal speciation and cause intense cycling of metals between sediment, pore water, and plant tissue. The proposed research will use electrochemical techniques in combination with a solid-state voltammetric microelectrode to determine concentrations, properties, and fluxes of metals and metal-complexes. The fact that invertebrates and roots are hidden from view is a major impediment to understanding organism-sediment interactions. We will visualize the distributions of roots and invertebrates with CAT-scan analysis of intact cores. The 3-D images will guide the positioning of microelectrodes and let us measure oxygen, sulfide, iron, and manganese near surfaces of burrow and roots. 3-D images of root distributions will let us estimate how root biomass and oxygen flux evolve during the growth season.

对金属环境化学的兴趣源于金属对生物体的根本重要性，以及人们认识到人类的活动已经改变了金属的自然循环。金属通过不同的途径进入环境，并通过海底沉积和掩埋而被清除。在金属被埋得很深，以至于它们被永久地移走，成为地质记录的一部分之前，它们参与了由沉积环境中的生物介导的化学和生物化学反应。该提案将研究沉积物中生物-沉积物的相互作用，其中主要的大型生物是无脊椎动物或植物。重点将放在由生物体产生的金属结合有机化合物，以及它们与金属离子形成的复合物上。这些配合物与未配合的金属相比，具有不同的溶解度、迁移率、可用性和毒性。无脊椎生物建造洞穴和通道，扩大沉积物和上覆水之间的接触，并刺激沉积物和水之间复杂和非复杂金属的交换。潮间带维管植物不影响金属与水柱的交换，但它们中空的根运输氧气，从而氧化还原的沉积物。根也释放金属结合有机酸。根的生长和腐烂产生金属形态的深刻变化，并引起金属在沉积物、孔隙水和植物组织之间的强烈循环。拟议的研究将使用电化学技术与固态伏安微电极相结合来确定金属和金属配合物的浓度、性质和通量。无脊椎动物和树根隐藏在视野之外，这是理解生物-沉积物相互作用的主要障碍。我们将通过完整岩心的ct扫描分析来可视化树根和无脊椎动物的分布。3d图像将指导微电极的定位，让我们测量洞穴和根部表面附近的氧气、硫化物、铁和锰。根系分布的三维图像将使我们估计根系生物量和氧通量在生长季节如何演变。