Atmospheric Mineral Nanoparticles in Antarctic Ice during the last Climatic Cycle

上一个气候周期期间南极冰中的大气矿物纳米颗粒

• 批准号: 1744961
• 负责人: John Olesik
• 金额: $ 69.31万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744961&HistoricalAwards=false
• 关键词: Atmospheric; Mineral; Nanoparticles; Antarctic; Ice

The main goal of this project is to identify and geochemically characterize atmospheric mineral nanoparticles in pre-industrial Antarctic ice during the last climatic cycle. Recent technological and industrial development is introducing a large number of natural and engineered nanoparticles into Earth's atmosphere. These constitute a concern for human health, mainly due to their high chemical reactivity. While many atmospheric nanoparticle studies have been performed in modern urban environments, there is essentially no information about their occurrence in a pristine pre-industrial atmosphere. This information is critical, as it constitutes an important benchmark for comparison to the modern atmosphere. Information on nanoparticles from the pre-industrial atmosphere can be obtained from atmospheric mineral nanoparticles that are entrapped in remote pre-industrial Antarctic ice covering the last climatic cycles. Mineral nanoparticles can also affect several climatic processes. First, they directly influence the global energy balance by reflecting solar radiation and indirectly influence through changes in cloud formation (and clouds also reflect solar radiation). Second, atmospheric mineral nanoparticles such as iron oxides could have fertilized the oceans, causing blooms of marine phytoplankton that may have drawn part of the atmospheric carbon dioxide into the oceans during glacial ages (the "biological pump"). Third, a significant amount of extraterrestrial material entering the Earth atmosphere is thought to be transported to the poles as nanoparticles called "meteoric smoke" that form polar stratospheric clouds implicated in changes of the ozone hole.This project aims to establish the natural background of unknown classes of glacial particles whose size is below the detection limit of the conventional dust analyzers. The team will take advantage of ice samples from the "horizontal ice core", already extracted from the remote Taylor Glacier (coastal East Antarctica) covering the last ~44,000 years. These ancient samples are particularly suited to project scope because i) a large ice volume is available ii) the team expects to find a markedly different geochemistry between nanoparticles deposited during the last glacial age and during the current interglacial. A set of advanced techniques including Transmission Electron Microscopy, Single Particle Inductively Coupled Plasma Mass Spectrometry (spICP-MS), spICP-Time of Flight MS, and Field Flow Fractionation will be employed to determine mineral nanoparticle sizes, number/volume, and chemical composition. So far, the elemental composition of dust entrapped in polar ice has been mainly determined by Inductively Coupled Plasma Sector Field Mass Spectrometry and it is generally assumed to be descriptive of the coarse aeolian dust fraction. However, project will test whether or not the determined elemental composition is instead mainly linked to the previously unobserved smaller mineral nanoparticle content. Results on nanoparticles will be compared with a set of new experiments of total dust composition measured by Inductively Coupled Plasma Sector Field Mass Spectrometry, using the same ice samples from Taylor Glacier.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目的主要目标是确定上一个气候周期中工业化前南极冰层中的大气矿物纳米颗粒并对其进行地球化学性质的表征。最近的技术和工业发展正在将大量的天然和工程纳米颗粒引入地球大气层。这些物质对人类健康构成了威胁，这主要是因为它们具有很高的化学反应活性。虽然许多大气纳米颗粒的研究都是在现代城市环境中进行的，但基本上没有关于它们在原始的前工业化大气中出现的信息。这一信息至关重要，因为它构成了与现代大气进行比较的重要基准。有关工业化前大气中的纳米颗粒的信息可以从覆盖上一个气候周期的遥远的工业化前南极冰层中捕获的大气矿物纳米颗粒中获得。矿物纳米颗粒也会影响几个气候过程。首先，它们通过反射太阳辐射直接影响全球能量平衡，并通过云形成的变化间接影响(云也反射太阳辐射)。其次，像氧化铁这样的大气矿物纳米颗粒可能使海洋肥沃，导致海洋浮游植物大量繁殖，这些浮游植物可能在冰河时代将部分大气二氧化碳吸收到海洋中(“生物泵”)。第三，进入地球大气层的大量外星物质被认为以纳米粒子的形式被输送到两极，这些纳米粒子被称为“陨烟”，形成极地平流层云，与臭氧层空洞的变化有关。该项目旨在建立未知类别冰川颗粒的自然背景，这些颗粒的大小低于传统尘埃分析仪的检测下限。该团队将利用从遥远的泰勒冰川(东南极洲沿海)提取的“水平冰芯”的冰样，覆盖过去约44,000年。这些古老的样品特别适合于项目范围，因为i)有大量的冰块可用；ii)研究小组希望在上一次冰川时期和当前间冰期沉积的纳米颗粒之间发现明显不同的地球化学性质。将使用一套先进的技术，包括透射电子显微镜、单粒子电感耦合等离子体质谱(SPICPMS)、飞行时间质谱仪和场流分选技术来确定矿物纳米颗粒的尺寸、数量/体积和化学成分。到目前为止，极地冰层中尘埃的元素组成主要是通过电感耦合等离子体扇区场质谱来确定的，一般认为它描述的是粗风尘分数。然而，该项目将测试所确定的元素组成是否主要与之前未观察到的较小矿物纳米颗粒含量有关。关于纳米粒子的结果将与一组新的实验进行比较，这些实验使用来自泰勒冰川的相同冰样，使用电感耦合等离子体扇区场质谱测量总粉尘成分。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。