EAPSI:Typhoon Impacts on Chemical Weathering in a Mountainous Island Watershed in Taiwan

Meyer Kevin J, Columbus OH

Investigators

Abstract

High standing islands such as Taiwan represent a major source of sediment and carbon transport to the oceans, but sparse data exist for chemical weathering rates and weathering sources in these terrains. Almost no data exist on the impact of typhoons and other extreme weather on chemical weathering rates. This award supports research that will determine chemical weathering rates within the Gaoping River watershed, and how they changed in response to Typhoon Mindulle (2004). It will also use several geochemical tools to constrain the sources of chemical weathering to the river, and how these sources may change in response to a typhoon. This research will be conducted under the supervision of Dr. Chen-Feng You at National Cheng Kung University, an expert in mass spectrometry techniques necessary for analysis, and an ideal collaborator for this study. Chemical weathering is a major control on atmospheric carbon dioxide levels over geological time, and high standing islands have been shown to have some of the highest weathering rates worldwide, yet the role of local weather in the global carbon cycle is poorly understood. This study will add new insight into the long term controls of earth?s climate and carbon cycle. Determining typhoon impacts on chemical weathering will primarily be accomplished through geochemical analysis of river waters collected during Typhoon Mindulle. Different tributaries to the Gaoping River drain rocks with distinct strontium (Sr) isotope and elemental compositions. Thermal Ionization Mass Spectrometry will be used to determine Sr isotope ratios, and Ion Chromatography will be used to determine major ion composition of the river waters. These analyses will be used to determine the relative weathering inputs of different lithologies of the watershed. Dissolved silica is commonly used as a proxy for chemical weathering, and will be measured and used in conjunction with historical stream gauge records to determine total chemical weathering input into the river system over the course of the storm. These analyses will be compared to similar analyses conducted by Dr. You during normal dry and wet season flow in the Gaoping watershed to determine changes attributable to the typhoon. This NSF EAPSI award is funded in collaboration with the Ministry of Science and Technology of Taiwan.