The supply of iron from shelf sediments to the ocean

浮游植物(微型藻类)位于海洋食物链的底部，因此它们的存在对于维持鱼类等高等生物是必不可少的。它们还吸收与陆地植物一样多的大气二氧化碳，这样做有助于调节全球气候。铁是浮游植物生长所需的最重要的营养物质之一，并被用于重要的生物功能，包括光合作用(将二氧化碳和水转化为葡萄糖和氧气)。铁在陆地和周围的浅海水域富含铁，这些水域被称为“陆架区”。相比之下，铁以非常低的浓度存在于远离陆地的深海中(每10亿个水分子中不到1个铁原子)。这意味着浮游植物的生长可能会因为缺铁而受到限制。由于铁的化学性质，它在从海岸运输到开阔的海洋时会丢失--它在海水中非常不溶。然而，来自沿海地区的少量铁确实到达了开阔的海洋，这些铁构成了供应给那里生长的浮游植物的新铁的很大一部分。对海洋铁化学的研究要求我们确定有多少铁，铁的化学形态(例如，溶解的形态或颗粒)以及在这些不同形态之间发生的变化。这些不同形式的数量随着一年中的时间、水的位置、颗粒的数量和海水中的有机分子而变化。在海水中极低浓度的铁的采样和测量是具有挑战性的，申请者是世界上少数几个能够可靠地做到这一点的研究小组之一。在这个项目中，我们解决了洋流、潮汐、天气和海洋铁化学如何允许新的铁从英国周围的浅海陆架水域运输到附近的开阔海洋的问题。该项目最终将使我们能够解决更广泛的问题，即沿海水域和陆架沉积物中铁的数量和化学形态如何影响公海浮游植物的生长。此外，人类活动和气候变化对英国陆架地区铁运输的影响还知之甚少。这一点很重要，因为通过改变对开阔海洋的铁供应来改变海洋生产力，也会改变浮游植物吸收的二氧化碳数量。

Phytoplankton (microscopic algae) lie at the base of the marine food chain, so their presence is essential for sustaining higher organisms such as fish. They also take up as much atmospheric carbon dioxide as land plants and in doing so, help regulate the global climate. Iron is among the most important nutrients required by phytoplankton to grow and is used in vital biological functions, including photosynthesis (conversion of carbon dioxide and water into glucose and oxygen). Iron is abundant on land and in surrounding shallow coastal waters, known as 'shelf regions'. In contrast, iron is present at very low concentrations (less than 1 iron atom to every billion water molecules) in the deep open ocean, far from land. This means that the growth of phytoplankton can be restricted due to the lack of iron. Iron is lost as it is transported from the coast to the open ocean because of its chemistry - it is very insoluble in seawater. However, a small amount of iron from coastal regions does reach the open ocean and this iron makes up a large portion of the new iron supplied to the phytoplankton growing there. Studies of marine iron chemistry require us to determine how much iron there is, what chemical forms iron is in (e.g. dissolved forms or particles) and the changes that occur between these various forms. The amounts of these different forms change depending on the time of year, the location of the water, the number of particles and the organic molecules in seawater. Sampling and measurement of iron at very low concentrations in seawater is challenging and the applicants are among the few research groups in the world who are able to do this reliably.In this project we address the question of how currents, tides, weather and marine iron chemistry allow new iron to be transported away from the shallow shelf waters around the UK, to the nearby open ocean. The project will ultimately allow us to address the broader question of how the amount and chemical form of iron in coastal waters and shelf sediments can influence phytoplankton growth in the open ocean. Furthermore, the impact of human activity and climate change on the transport of iron from the UK shelf region is poorly understood. This is important because changing ocean productivity by changing iron supply to the open ocean will also alter the amount of carbon dioxide taken up by phytoplankton.