Faculty Mentor

Dr. Carmen Nezat

Document Type


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Chemical weathering is an ongoing natural phenomenon that aids in the breakdown of solid rocks and contributes to the chemistry of natural waters and soils. Therefore, studying chemical weathering in a given area may provide a better understanding of the natural influencers on nearby water chemistry. The eruption of Mount St. Helens (MSH) in 1980 provides a unique opportunity to study the chemical weathering of young rocks which typically weather more rapidly than older rocks.

The aim of the study was to determine the relative resistance of the volcanic rocks from the 1980 MSH eruption to chemical weathering by using a sequential leaching process. Sediments were collected from the streams and leached with the following solutions to simulate chemical weathering: ultra-pure water (H2O), 1 N acetic acid (CH3COOH), and 1 N nitric acid (HNO3). The leaches were analyzed for Ca, Na, K, Fe, Mg, and Al using an inductively coupled plasma optical emission spectrotrometer (ICP-OES). Results show that each successive leach was capable of breaking down more resistant minerals. Future research includes interpreting the composition of the leaches to determine which minerals each removed from the stream sediments.