Doctoral Dissertation Research: Temporal Variations in Pacific Ocean Dust Fluxes

本博士论文研究项目调查了亚洲在太平洋岛屿上的粉尘沉积历史，以及气候变化如何影响过去43,000年的粉尘沉积率。来自亚洲沙漠的沙尘含有铁和磷，这两种营养物质可以极大地影响北太平洋的生态系统。沙尘流入受三个主要过程的差异影响，即空气中的沙尘量、长距离风运输和通过降雨进入海洋或土壤的沙尘沉降。尽管有这些重要的联系，但尚未有关于太平洋岛屿上亚洲沙尘通量时间变化的长期记录。通过分析从夏威夷泥炭沼泽中提取的几个岩心中可用的替代测量，博士生将生成太平洋岛屿上亚洲尘埃通量的原始长期记录。这一记录将有助于更好地探测亚洲沙尘通量-气候-生态系统的相互作用、变化和超越现代观测的时间尺度。这项新记录将通过几个可广泛访问的数据库提供，其他研究人员可以利用这些数据库正在努力模拟尘埃在大气过程中的作用。研究结果还将用于开发威斯康星州少数民族和低收入高中学生的科学丰富活动。一些太平洋岛屿（如夏威夷）土壤中丰富的石英表明，从东亚沙漠到北太平洋的大陆尘埃不断增加。本项目主要有三个研究目标：1)重建夏威夷石英聚集速率的历史；2)区分古沙尘记录中气候与人为石英通量；3)对比石英通量古记录与独立的气候历史记录，推断气候变化对夏威夷沙尘沉积的影响。代表亚洲尘通量的石英累积率、代表亚洲尘运至夏威夷的风强度的平均石英粒度、代表夏威夷古水文的有机碳累积量、C/N比和Br含量，以及代表人为引起的当地尘排放强度的平均粒度分布。通过重建和关联这些代理，博士生将展示气候变化如何影响夏威夷过去43,000年的亚洲沙尘通量。研究结果将有助于建立气候、大气尘埃和偏远生态系统之间联系的模型。

This doctoral dissertation research project investigates the history of Asian dust deposition on islands in the Pacific and how variability in climate has impacted rates of dust deposition over the past 43,000 years. Asian dust from deserts contains iron and phosphorous, two nutrients that can greatly influence ecosystems in the North Pacific. Dust influxes have been influenced by differentials in three major processes, the amount of dust in the air, long-distance wind transport, and dust settling via rainfall to the ocean or soils. Despite these important connections, long-term records of temporal variations in Asian dust flux onto islands in the Pacific have not been reported. By analyzing proxy measures available in several cores extracted from peat bogs on Hawai'i, the doctoral student will generate an original long-term record of Asian dust flux on islands in the Pacific. This record will help better detect Asian dust flux-climate-ecosystem interactions, variations, and timescales beyond those available in modern observations. This new record will be made available through several broadly accessible databases which can be used by other investigators in ongoing efforts to model the role of dust in atmospheric processes. The research results will also be used to develop a science enrichment activity for minority and low-income high school students in Wisconsin. The abundance of quartz in the soil of some Pacific islands such as Hawai'i demonstrates continuous addition of continental dust from East Asian deserts to the North Pacific. This project focuses on three research objectives: 1) reconstructing the history of quartz accumulation rates in Hawai'i; 2) distinguishing climate- from human-induced quartz flux in the paleodust records; and 3) comparing the quartz flux paleorecords with independent records of climate history to infer the influence of climate change on dust deposition in Hawai'i. Proxies include quartz accumulation rates for Asian dust flux, mean quartz grain size for the intensity of winds transporting Asian dust to Hawai'i, organic carbon accumulation, C/N ratio and Br content for Hawaiian paleohydrology, and mean grain size distribution for human-induced local dust emission intensity. By reconstructing and correlating these proxies, the doctoral student will demonstrate how climatologic variation has influenced Asian dust flux in Hawai'i over the last 43,000 years. The results will contribute to ongoing efforts to model the linkages among climate, atmospheric dust, and connections among remote ecosystems.