Iron Biogeochemistry in the High Latitude North Atlantic

自工业革命开始以来，由于燃烧化石燃料和砍伐森林，二氧化碳的浓度显著增加。二氧化碳影响着地球上的气候，现在它的浓度如此之高，以至于地球的大气正在变暖，天气变得更加极端。海洋中被称为浮游植物的小型漂浮植物从大气中吸收二氧化碳，从而有助于降低大气中的二氧化碳浓度。浮游植物细胞也需要氮、磷和硅等营养物质来生长。最近，人们发现世界海洋许多地区的浮游植物缺乏铁。例如，在南大洋，浮游植物细胞的生长受到非常低的铁浓度的限制。因此，这片海洋中的浮游植物从大气中吸收的二氧化碳不如它们在理想条件下所能做的那么多。许多人认为北大西洋通过撒哈拉沙漠的沙尘运输获得了足够的铁。然而，最近的实验表明，即使在北大西洋的浮游植物细胞也可能缺乏铁。在这个项目中，我们想研究铁是否限制了北大西洋高纬度地区（bbb60 N）浮游植物的生长。为了实现这一目标，我们将参加3次研究巡航，采集水、沉积物、大气尘埃和雨水的样本。我们将分析样品中的铁和营养物质，并计算铁与N、P、C向表层海洋的供应比例，以及它们在沉积物中的比例。我们将使用模型来帮助我们计算这些元素的海洋转移。如果浮游植物在北大西洋高纬度地区的铁含量有限，那是因为它们从其他营养物质中获得的铁含量太低了。我们还将直接调查铁是否限制了北大西洋高纬度水样中浮游植物的生长。为了找到答案，我们将在甲板上的透明瓶子里培养从海洋表面提取的浮游植物细胞。我们会在一些瓶子里添加Fe，而其他瓶子根本没有添加Fe。浮游植物的生长和生理状态将通过一些测量来确定，例如色素（叶绿素a）浓度。这些测量结果将告诉我们，与没有添加铁的瓶子相比，添加了铁的瓶子是否显示出更多的浮游植物细胞和更高的生长速度。拟议项目的结果将使我们更好地了解像铁这样的营养物质在海洋浮游植物细胞生长中的作用。收集到的数据将帮助计算机建模者设计改进的气候模型，使我们能够更好地预测未来100年气候变化的范围。

The concentration of carbon dioxide has increased significantly since the start of the industrial revolution as a result of burning of fossil fuels and deforestation. Carbon dioxide influences the climate on earth and its concentration is now so high that the earth's atmosphere is warming and the weather is becoming more extreme. Small floating plants in the ocean, called phytoplankton, take up carbon dioxide from the atmosphere and that way help to reduce the atmospheric concentrations. The phytoplankton cells also need nutrients like nitrogen, phosphorus and silicon to grow. Recently, it has been discovered that the phytoplankton in many regions of the world's oceans are lacking Fe. For example, in the Southern Ocean the growth of the phytoplankton cells is limited by very low Fe concentrations. Therefore, the phytoplankton in this ocean do not remove as much carbon dioxide from the atmosphere as they could do under ideal conditions. Many people think that the North Atlantic Ocean receives enough Fe through dust transport from the Sahara. However, recent experiments have shown that even in the North Atlantic phytoplankton cells may be lacking Fe. In this project, we want to study whether Fe is limiting phytoplankton growth in the North Atlantic at higher latitudes (>60 N). In order to achieve this, we will take part in 3 research cruises and take samples of water, sedimenting material, and atmospheric dust and rain. We will analyse Fe and nutrients in the samples and calculate the supply ratios of Fe to N, P, C to the surface oceans, and their ratios in sedimenting material. We will use models to aid us with the calculations for the oceanic transfers of these elements. If the phytoplankton are Fe limited in the high latitude N Atlantic then it will be because the amount of Fe they get in relation to other nutrients is too low. We will also directly investigate whether Fe is limiting the growth of phytoplankton in water samples from the high latitude N Atlantic. To find this out, we will grow phytoplankton cells taken from the surface ocean in transparent bottles on the deck of the ship. We will add Fe to some bottles, whereas other bottles will receive no added Fe at all. The growth and physiological state of the phytoplankton will be determined using a number of measurements, such as pigment (chlorophyll a) concentrations. These measurements will show us whether the bottles with added Fe show a higher number of phytoplankton cells and a higher growth, compared with the bottles to which we added no Fe. The results of the proposed project will provide us with a better understanding of the role that nutrients like Fe play in the growth of phytoplankton cells in the ocean. The gathered data will help the computer modellers to design improved climate models that will allow us to better predict the extend of climate change over the next 100s of years.