Collaborative Research: GEOTRACES particulate intercalibration

大采样和方法偏差，报告的差异高达200%，继续混淆海洋地球化学研究界参与水柱微粒采样。在设计GEOTRACES相互校准巡航（IC）计划时，没有充分认识到所报告的差异的程度和真实性。解决这一问题仍然是一个紧迫的优先事项。在该项目中，加州大学伯克利分校-劳伦斯伯克利国家实验室和伍兹霍尔海洋研究所的研究人员将参与US-GEOTRACES IC研究。UCB/LBNL团队将部署多单元大容量原位过滤系统（MULVFS）作为IC研究的一部分。MULVFS是一个独特的、高度灵活的、可靠的系统，具有无与伦比的、经过全球测试的从海洋中收集颗粒和溶解物质的能力。MULVFS从1000 L体积的海水中收集10000米以上12个深度层位的粒度分级颗粒样品。将向其他IC实验参与者提供子样本。作为IC实验的一部分，LBNL/UCB将分析来自瓶和McLane泵的微粒样品。MULVFS还将用于同时比较不同的颗粒捕获和尺寸分离装置（例如McLane、Challenger、基尔泵过滤器支架）、过滤器类型和吸附器系统。这项工作得到了GEOTRACES国际中心PI和参与者以及GEOTRACES科学指导委员会成员的高度协调。将通过该奖项开展的工作旨在消除GEOTRACES颗粒物采样对研究者和采样方法的依赖性，并将协调该计划中使用的各种采样方法。工作将支持多调查员颗粒物IC研究，使用MULVFS在环境容易的位置，如BATS和SAFe网站，并在物理动态和生物可变的位置，如在墨西哥湾流和加州电流。MULVFS的设计目的是在墨西哥湾流的强水流中保留颗粒。在具有挑战性和非挑战性的环境中与其他颗粒采样方法进行比较，将有助于理解和解决已发表文献中记录的实质性偏倚/差异，并在本提案中进一步记录。这样的内部校准以前从未进行过。此外，MULVFS通过提供上层水柱中痕量金属和核素的高分辨率基线剖面，大大提高了IC实验的效率。GEOTRACES高度重视颗粒物样品，这些样品在水柱中天然存在的颗粒物的组成和粒度分布方面具有代表性，无论水柱是温暖的、寒冷的、静止的还是物理动态的或生物可变的。更广泛的影响：拟议的工作解决了非常真实的问题的方法依赖的颗粒采样和分析前的偏见（大颗粒损失，从一些泵，大颗粒沉降损失之前，在瓶子中过滤，样品保存不良等）。它将与从事微粒研究的海洋学界所有成员有关。

Large sampling and methodological biases, with reported differences as large as 200%, continue to confound the marine geochemical research community involved in water-column particulate sampling. When the GEOTRACES Intercalibration Cruise (IC) program was designed, the extent and reality of reported differences had not been fully appreciated. The resolution of this problem remains an urgent priority. In this project, researchers at the University of California Berkeley - Lawrence Berkeley National Laboratory and the Woods Hole Oceanographic Institution will participate in the US-GEOTRACES IC study. The UCB/LBNL team will deploy Multiple Unit Large Volume in-situ Filtration System (MULVFS) as part of the IC study. MULVFS is a unique, highly flexible, and reliable system with an unparalleled and globally tested ability for collection of particulate and dissolved species from the sea. MULVFS collects size fractionated particulate samples from 10000 L volumes of seawater at 12 depth horizons in the upper 1000 m. Subsamples will be provided to other IC experiment participants. LBNL/UCB will analyze particulate samples from bottle and McLane pumps as part of the IC experiment. MULVFS will also be used for simultaneous comparison of different particle capture and size separation devices (e.g. McLane, Challenger, Kiel pump filter holders), filter types, and adsorber systems. This work has been highly coordinated with the GEOTRACES IC PIs and participants as well as with members of the GEOTRACES Science Steering Committee. The work that will be carried out through this award is designed to eliminate investigator and sampling approach dependency for GEOTRACES particulate sampling and will reconcile the various sampling approaches to be used in this program. Work will support multi-investigator particulate matter IC studies using MULVFS in both the environmentally easy locations such as the BATS and SAFe site and in physically dynamic and biologically variable locations such as in the Gulf Stream and California Current. MULVFS was designed to retain particles in strong current flows of the Gulf Stream. Comparison with other particle sampling methodologies in both challenging and non-challenging environments will lead to understanding and resolution of biases /differences that are both substantial, documented in published literature, and further documented in this proposal. Such an inter calibration has never been done before. Furthermore, MULVFS greatly improves the efficiency of the IC experiment by providing high resolution baseline profiles of trace metals and nuclides in the upper water column. GEOTRACES places high priority on particulate matter samples being representative in composition and size distribution of the particulates naturally occurring in the water column whether or not the water column is warm, cold, quiescent or physically dynamic or biologically variable. Broader Impacts: The proposed work tackles the very real problems of method-dependent particle sampling and pre analysis biases (large particle loss from some pumps, large particle settling loss before filtration in bottles, poor sample preservation, etc.). It will be of relevance to all members of the oceanography community who engage in particle studies.