Development of a consistent thermodynamic model of trace element - organic matter interactions in the Ocean.

微量元素可以限制海洋的生产力，从而影响海洋浮游植物从大气中去除的二氧化碳量。对浮游植物生长最关键的微量元素是铁，它限制了世界上大约30%海洋的生产力。需要在将铁纳入生物地球化学模型和气候模型方面取得进展，以便考虑铁对二氧化碳对地球气候的影响。将铁纳入生物地球化学和气候模型需要对海水中铁的化学性质有基本的了解，因为铁的化学性质受到海洋pH值、温度和溶解有机碳浓度的影响。众所周知，有机物质对铁的化学反应有重大影响，但目前对铁和有机物质之间的相互作用的描述过于简单，与基本原理无关。在这个项目中，我们建议使用最先进的方法来参数化海水中铁的化学成分，这些方法实际地代表了有机物的复杂性，以及有机物与海洋环境中铁和其他微量元素相互作用的方式。重要的是，我们的方法采用了NICA模型——一个以热力学理论为基础的模型，并在淡水水生环境中进行了试验和测试。我们假设使用NICA模型来解释海水中的铁化学将提高我们将铁化学与溶解有机碳和海洋酸度的行为联系起来的能力。我们的目标是确定在海水中应用NICA模型所需的参数。我们将把这个模型应用于在亚马逊河的羽流中观察到的情况，亚马逊河是流入海洋的最大河流。我们的方法将使我们能够检查有机物和pH值在铁的海上运输中所起的作用，从而提高我们对控制铁流入海洋的河流通量的因素的理解。

Trace elements can limit productivity in the ocean, and thus influence the amount of carbon dioxide that marine phytoplankton remove from the atmosphere. The most critical trace element for phytoplankton growth is iron, which limits productivity in approximately 30 % of the worlds' ocean. Progress with respect to incorporation of iron into biogeochemical models and climate models is required, in order to account for its influence on the impact of carbon dioxide on the earths' climate. Incorporation of iron into biogeochemical and climate models needs to be underpinned by a fundamental understanding of the chemistry of iron in seawater, since iron chemistry is affected by ocean pH, temperature and the concentration of dissolved organic carbon. Organic matter is known to have a major influence on iron chemistry, but interactions between iron and organic matter are currently described in a simplistic way that do not relate to fundamental principles. In this project we propose to parameterise the chemistry of iron in seawater using state of the art approaches that realistically represent the complexity of organic matter and the way organic matter interacts with iron and other trace elements in the marine environment. Importantly our approach adopts the NICA model - a model that is grounded in thermodynamic theory and has been tried and tested in fresh water aquatic environments. We hypothesise that use of the NICA model for interpretation of iron chemistry in seawater will improve our ability to link iron chemistry to the behaviour of dissolved organic carbon and ocean acidity. Our objectives are to determine the parameters required to apply the NICA model in seawater. We will apply the model to conditions observed in the plume of the River Amazon which constitutes the largest riverine input to the ocean. Our approach will allow us to examine the role that organic matter and pH play in the offshore transportation of iron, thereby improving our understanding of the factors that control riverine fluxes of iron to the ocean.