Doctoral Dissertation Research: Temporal Variations in Pacific Ocean Dust Fluxes

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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.