Seasonal controls on shelf-edge nutrient fluxes at the Malin Shelf

营养物质对海洋中浮游植物的生长至关重要。浮游植物从周围的水中吸收养分，它们的生长程度在很大程度上取决于养分的可获得性。硝酸盐和磷酸盐是至关重要的营养物质，它们存在于光照丰富的地表水域，可以维持藻类的水华。浮游植物从大气中吸收二氧化碳，而在陆架海洋中，浮游植物可以将这些碳锁定在沉积物中。在这个项目中，我们将研究这样的观点，即陆架海洋的季节性营养物质供应是由陆架边缘的物理混合过程控制的。这将使用能够现场测定硝酸盐和磷酸盐的新传感器进行，这种传感器将在水下滑翔机上一次部署长达3周。水下滑翔机是一种自动飞行器，从靠近海岸的地方发射后，可以“飞”到采样点，并通过卫星链路发回数据。我们将在一个季节性的时间尺度上使用四次滑翔机任务(2013年6月和9月，2014年1月和4月)，以便从根本上深入了解马林架周围高生产力陆架海域的年度营养物质供应。除了滑翔机上的营养传感器，还将有另外三个传感器，一个电导率和温度传感器，一个氧气传感器和一个可以测定作为水中浮游植物生物量替代品的叶绿素a的传感器。对于每一次任务，我们将使用两个滑翔机同时描述货架上和货架外的浓度梯度。这些滑翔机任务将被整合到一个由NERC资助的大型财团Fastnet中，该财团旨在确定促进西北欧大陆架边缘水交换的物理过程，并了解它们如何随季节演变。Fastnet将在同一地点部署长期的陆架边缘海流计系泊设施和另一种水下自动潜航器Autosub Long Range(ALR)。部署在滑翔机上的传感器的使用使我们能够扩大数据的空间和时间覆盖范围，这是传统的船上测量无法实现的，也是在暴风雨条件下无法进行的。对马林大陆架发生的物理过程的深入了解与来自传感器的准确的高分辨率营养数据相结合，意味着我们将能够调查是什么控制着光层的营养供应，以及这对浮游植物生长的影响。此外，我们将试验这些水下滑翔机的新部署方法-使用快速日船将它们带到离海岸基地尽可能远的地方。我们的数据将免费提供，我们将在整个项目中与最终用户(如负责渔业的英国政府环境、食品和农村事务部，以及英国气象局)分享我们的发现。

Nutrients are essential for phytoplankton growth in the sea. Phytoplankton take up nutrients from the surrounding water and the extent of their growth is largely dependent on nutrient availability. Nitrate and phosphate are vital nutrients and their presence in light-rich surface waters can sustain algal blooms. Phytoplankton draw down carbon dioxide from the atmosphere and in shelf seas can lock this carbon up in the sediments. In this project we will investigate the idea that the seasonal supply of nutrients to shelf seas is controlled by physical mixing processes at the shelf edge. This will be carried out using new sensors capable of determining nitrate and phosphate in-situ which will be deployed on underwater gliders for up to 3 weeks at a time. Underwater gliders are autonomous vehicles that, after launching from close to the coast, can "fly" to a sampling site and send back data via a satellite link. We will use four glider missions over a seasonal timescale (June & Sept 2013, Jan & April 2014) in order to gain a fundamental insight into the annual supply of nutrients to the highly productive shelf seas around the Malin Shelf. Alongside the nutrient sensors on the gliders will be three other sensors, a conductivity and temperature sensor, an oxygen sensor and a sensor which can determine chlorophyll a which is used as a proxy for phytoplankton biomass in the water. For each mission we will use two gliders to simultaneously characterise both the on- and off-shelf concentration gradients. These glider missions will be integrated into a large NERC-funded consortium, FASTNEt, which aims to identify the physical processes that facilitate the exchange of water across the edge of the north-west European shelf and understand how they evolve across the seasons. FASTNEt will be deploying long-term, shelf-edge current meter moorings and another underwater autonomous vehicle, the Autosub Long Range (ALR) in the same location. The use of sensors deployed on gliders allow us to increase the spatial and temporal coverage of data that would not be possible from traditional shipboard measurements, that cannot be carried out in stormy conditions. The combination of in-depth knowledge of the physical processes occurring at the Malin Shelf along with accurate high resolution nutrient data from the sensors means that we will be able to investigate what controls nutrient supply to the photic zone and how this impacts on the phytoplankton growth.Additionally, we will be trialling new deployment methodologies for these underwater gliders - using fast day-boats to take them as far offshore as possible from a coastal base.Our data will be freely available and we will share our findings with end-users (such as the UK government's Department for Environment, Food and Rural Affairs who are responsible for fisheries, and the UK Met Office) throughout the project.