Trace metal-Organic matter interactions in seawater: Exploring the impact of seawater chemistry on trace metal speciation in a warming and acidifying ocean.

海水中的痕量金属-有机物相互作用：探索海水化学对海洋变暖和酸化中痕量金属形态的影响。

• 批准号: 499587781
• 负责人: Dr. Kechen Zhu
• 金额: --
• 依托单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/499587781?language=en
• 关键词: Trace; metal; Organic; matter; interactions

Trace metals (TMs), defined as less than 1 mg kg-1, are either important essential nutrients (Fe, Mn, Co, Cu, Ni, Zn) for microbial growth, or toxic (Cu, Pb, Cd) at elevated concentrations in seawater. The Ocean is currently experiencing deoxygenation, acidification, stratification and warming, resulting in changes in chemical speciation of TMs that are dependent on the physico-chemical conditions (e.g. pH, temperature and salinity). Whilst knowledge of dissolved and particulate metals provides information on total inventories and allows for identification of important sources of TMs to the marine environment, knowledge of chemical speciation is essential for understanding the biogeochemistry and bioavailability or toxicity of TMs. For example, previous work shows that inorganic Fe has a poor solubility in oxygenated seawater, but dissolved Fe concentrations are higher than expected because of complexation by organic matter. However current knowledge of TMs speciation is observed for a specific sample at laboratory conditions (e.g. pH=8.0, on the NBS scale), and therefore lack a mechanistic link to the intrinsic physico-chemical properties of seawater and their influence on metal binding to organic matter. Here I develop novel analytical and modelling tools, and utilize metal-resin/organic matter interactions to accurately determine TM speciation by ICP-MS over a wide range of pH values. I combine these measurements with an ion paring-organic matter (NICA-Donnan) model to develop a mechanistic description of the interactions and thereby improve our understanding of the roles of e.g. pH, temperature and ionic strength on marine TM cycling. Once this methodology is achieved, it will allow us to simultaneously determine TM speciation for multiple metals for the first time, including those frequently investigated before and TMs where recent evidence from isotope abundance points to an important role for binding to organic matter. The derived thermodynamic constants will also be incorporated into regional biogeochemical models, in order to obtain predictions of TM biogeochemical cycling at a mechanistic level under future ocean scenarios.

微量金属（TMs），定义为低于1mg kg-1，要么是微生物生长的重要必需营养素（Fe, Mn, Co, Cu, Ni, Zn），要么是海水中浓度升高的有毒物质（Cu, Pb, Cd）。海洋目前正在经历脱氧、酸化、分层和变暖，导致依赖于物理化学条件（如pH值、温度和盐度）的TMs化学形态发生变化。虽然对溶解金属和颗粒金属的了解提供了有关总清单的信息，并允许确定海洋环境中TMs的重要来源，但对化学形态的了解对于了解TMs的生物地球化学和生物可利用性或毒性至关重要。例如，先前的研究表明，无机铁在含氧海水中的溶解度较差，但由于有机物的络合作用，溶解铁的浓度高于预期。然而，目前对TMs物种形成的了解是在实验室条件下对特定样品（例如pH=8.0，按NBS标准）观察到的，因此缺乏与海水固有的物理化学性质及其对金属与有机物结合的影响的机制联系。在这里，我开发了新的分析和建模工具，并利用金属-树脂/有机物相互作用，通过ICP-MS在广泛的pH值范围内准确地确定TM物种形成。我将这些测量结果与离子配对-有机物（NICA-Donnan）模型结合起来，开发了相互作用的机制描述，从而提高了我们对pH、温度和离子强度等因素在海洋TM循环中的作用的理解。一旦这种方法实现，它将使我们能够首次同时确定多种金属的TM形态，包括那些以前经常研究的金属，以及最近同位素丰度证据指向与有机物结合的重要作用的TM。得到的热力学常数也将被纳入区域生物地球化学模型，以便在未来海洋情景下在机制水平上预测TM生物地球化学循环。