High time resolution mineral dust deposition characterization with respect to particle size, composition and atmospheric ageing at locations relevant for the atmospheric-oceanic dust budget

湿沉降和干沉降是从大气系统中去除矿物粉尘的主要过程，矿物粉尘是主要的气溶胶类型之一。在适当的条件下，每年太克的尘埃可以在洲际尺度上运输。当矿物粉尘到达远离其源头的地球表面时，它可能会对生态系统产生重大影响。特别是，海洋生态系统的生产力因缺乏营养物质而受到限制，而营养物质可以由灰尘提供。此外，通过人工海洋施肥也存在地球工程的想法。尽管有如此高的影响，但对尘埃沉积的测量很少，而且通过少数可用数据集验证的模型性能很差。目前主要是缺乏详细的数据，这限制了我们对全球沙尘循环的了解。此外，干沉积测量技术的缺陷阻碍了适当数据的获取。在拟议的项目中，将开发一种新的自动湿法和干法沉积采样系统，并对其进行彻底的表征。该系统将在气象相关的时间尺度(小时至天)上收集样本，克服了过去测量沉积的问题，后者通常提供数周或数月的时间分辨率。通过使用自动扫描电子显微镜进行颗粒分析，该方法将提供前所未有的细节丰富的数据集。数据将包括直径在700纳米到100微米之间的粒度范围内的粒度分布、元素组成和颗粒混合状态。将特别注意潜在的营养素，铁、磷、钾、镁和钙。将测量选定样品的颗粒吸湿性。在弗里乌尔岛上的测试阶段结束后，采样器将与现有的时间序列进行验证，将在与向海洋输入粉尘有关的地点部署三台仪器：在佛得角圣文森特岛；在巴巴多斯，捕获撒哈拉沙漠外流；在冰岛海马伊岛，捕获北极粉尘。计划(在本项目之后)进行第二个项目阶段，网络将扩展到南美洲羽流中的福克兰新岛、日本阿马库萨岛的Araoteke、亚洲流出线以及位于南非东西向流出线和澳大利亚东西向流出线之间的阿姆斯特丹岛。该项目将首次提供连续的矿物粉尘干湿沉积系列，具有每日(干)或基于事件(湿)的时间分辨率和粒度分辨率。将描述导致沉积事件的大气关键因素。我们将评估营养物质--特别是铁和磷--在湿沉积和干沉积之间的分配情况，并确定相应的粒度分布。颗粒的混合状态和颗粒形状将通过混合模型和图像分析来评估。将提供一个公共数据库用于模型验证。计划在DFG筹资阶段结束后继续运作这些电台。

Wet and dry deposition are the major processes removing mineral dust, one of the major aerosol types, from the atmospheric system. Providing suitable conditions, teragrams of dust per year are transported on intercontinental scales. When mineral dust reaches the earth surface far away from its source, it may significantly influence ecosystems. In particular ocean ecosystems are limited in their productivity by lack of nutrients, which can be supplied by dust. Also, geo-engineering ideas exist by artificial ocean fertilization. Despite of this high impact, measurements of dust deposition are rare and model performance as validated by the few available data sets is poor. Mainly lack of detailed data is currently limiting our understanding of the global dust cycle. Moreover, deficits in dry deposition measurement techniques hamper acquisition of proper data.In the proposed project, a new automated wet and dry deposition sampling system will be developed and thoroughly characterized. The system will collect samples on meteorological relevant time scales (hours to days), overcoming the problem of past deposition measurements, which usually provided time resolution of weeks or months. By using automated scanning electron microscopy for particle analysis, the method will provide data sets of unprecedented detail richness. Data will include particle size distribution, elemental composition, and particle mixing state in the particle size range between 700 nm and 100 µm in diameter. Special attention will be given to the potential nutrients, iron, phosphorus, potassium, magnesium, and calcium. Particle hygroscopicity will be measured for selected samples.After the test phase on Frioul island, where the samplers will be validated with existing time series, three instruments will be deployed on locations relevant for dust input into the ocean: on the island of Sao Vicente, Cape Verde; Barbados, capturing Saharan outflow; and on Heimaey island, Iceland, capturing Arctic dust. A second project phase is planned (after present project), in which the network will be extended to New Island, Falkland, in the South American plume; to at Araoteke, Amakusa island Japan, Asian outflow; and to Amsterdam island, located between the South African west-east and Australian east-west outflow. The project will provide for the first time continuous series of mineral dust wet and dry deposition with daily (dry) or event-based (wet) time resolution and particle size resolution. Atmospheric key factors leading to deposition events will be characterized. We will assess the partitioning of nutrients - in particular of iron and phosphorus - between wet and dry deposition and will determine the according size distributions. Particle mixing state and particle shape will be assessed by mixing models and image analysis. A public database will be provided for model validation. It is planned that the stations will continue operation after the DFG funding phase.