Environmental Pollution as a Marine Tracer - Measuring and Modelling Anthropogenic Lead in the Indian Ocean

背景：人类活动增加了铅（Pb）的环境通量超过一个数量级。含铅汽油的燃烧在1970年代达到高峰，随后在全球逐步淘汰，因此产生了特别强烈的铅排放。在海洋中，铅污染的影响被清楚地记录下来，首先是北大西洋表层沃茨中铅浓度的上升，然后是下降。然而，铅水平仍在增加，在其他地区，如印度洋，由于不同国家之间的逐步淘汰的滞后和工业源的贡献，这也排放大量的铅。大量的人为铅污染尖峰可以用来研究海洋循环的铅。其理由是，铅排放物在大气中停留的时间很短，然后就会沉积到海洋中。Pb示踪剂的一个特别优点是该元素具有独特的同位素指纹。这种指纹可以在海洋中追踪，它揭示了铅的来源和地区，甚至是何时排放的。这使得在几十年到几百年的时间尺度上，跟踪海洋铅，无论它是来自灰尘输入的自然来源还是来自人为来源，如含铅汽油，燃煤或冶炼。因此，铅的同位素特征也可用于研究海洋内部的过程，如水团的运动和海洋生物地球化学。项目：该项目的目标是对印度和印度洋独特的海水、气溶胶和河流样本进行同位素分析，这是通过帝国理工学院和印度国家海洋学研究所之间的合作实现的。新的结果将使我们能够调查印度洋沿岸快速发展国家的铅排放量，这些国家的铅排放量在过去40年中显着增加。样品处理和分析将在伦敦帝国理工学院地球科学与工程系MAGIC实验室的洁净室和质谱设施中进行（http：//www.imperial.ac.uk/earth-science/research/research-groups/magic/）。该小组是世界上少数几个定期进行这些具有挑战性的分析的实验室之一。结果将随后用于模拟铅循环，无论是在大气输入方面，以及在海洋地球化学方面。您将成为GEOTRACES计划（www.example.com）的一部分www.geotraces.org，这是一项对微量元素和同位素的海洋循环进行国际研究的使命，旨在确定控制海洋中关键微量元素和同位素分布的过程和量化通量，并确定这些分布对环境条件变化的敏感性。地质学或同等资格，可以集中在各种方向。

Background: Human activities have increased the flux of lead (Pb) to the environment by more than an order of magnitude. The combustion of leaded gasoline, which peaked in the 1970s before a gradual global phase-out, thereby generated particularly strong Pb emissions. In the oceans, the effect of Pb pollution is clearly recorded, first in rising and then falling Pb concentrations in surface waters of the North Atlantic. However, Pb levels are still increasing in other areas, such as the Indian Ocean, due to the lag in phase-out between different countries and contributions from industrial sources, which also emit large quantities of Pb.The massive pollution spike of anthropogenic Pb can be used to study the marine cycle of Pb. The rationale is that Pb emissions remain in the atmosphere for only a short time before they are deposited in the ocean. A particular advantage of the Pb tracer is that the element has a distinct isotopic fingerprint. This fingerprint can be traced in the ocean, where it reveals from which source and region and even when the Pb was emitted. This enables, on timescales of decades to centuries, the tracking of marine Pb, regardless of whether it is of natural origin from dust inputs or derived from anthropogenic sources, such as leaded gasoline, coal burning or smelting. As such, the isotopic signature of Pb can also be used to study processes within the ocean, such as the movement of water masses and ocean biogeochemistry.The Project: This project will target isotopic analysis of unique seawater, aerosol and river samples from India and the Indian Ocean, made possible through a collaboration between Imperial College and the National Institute of Oceanography in India . The new results will allow us to investigate Pb emissions from the rapidly developing countries that border the Indian Ocean, where Pb emissions have increased significantly in the last 40 years. Sample processing and analyses will be carried out in the clean room and mass spectrometry facilities of the MAGIC Laboratories at the Department of Earth Science & Engineering, Imperial College London (http://www.imperial.ac.uk/earth-science/research/research-groups/magic/). The group is one of only a handful of laboratories world-wide where these challenging analyses are routinely conducted. Results will subsequently be used to model the Pb cycle, both in terms of atmospheric inputs, as well as in terms of ocean biogeochemistry. You will be part of the GEOTRACES program (www.geotraces.org), an international study of the marine cycles of trace elements and isotopes with the mission to identify processes and quantify fluxes hat control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.The project is suitable for a student with a background in oceanography, chemistry, geology or an equivalent qualification and can be focused in a variety of directions.