Analytical Chemistry Seminar: Jennifer Berry and Kevin Jansen
Analytical & Environmental Chemistry Division and Atmospheric Chemistry Program Seminar
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Light-absorbing impurities and spectral albedo of the Juneau Icefield
By Jennifer Lynne Berry - Department of Chemistry and Biochemistry, University of Colorado Boulder
Light absorption by ice is extremely low in the visible and near ultraviolet wavelengths, so small concentrations of light-absorbing impurities can have a large effect on snow and ice albedo. Snow samples containing light-absorbing impurities were collected alongside measurements of spectral albedo on the Juneau Icefield in Alaska to investigate this effect. An Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) was constructed to infer black carbon and non-black carbon light-absorbing particle concentrations in snow. Although calibration of the ISSW is incomplete, Nanoparticle Tracking Analysis and SEM-EDX images of particles from meltwater show a wide range of particle sizes and distribution across the icefield.
Chemical and Physical Alterations of Acid-Treated Aluminosilicate Clay Minerals and Impacts on Heterogeneous Ice Nucleation
By Kevin Jansen - Department of Chemistry and Biochemistry, University of Colorado Boulder
Mineral dust aerosol is a major contributor to global ice nucleation, although atmospheric processing of mineral dust by sulfuric and nitric acids has been found to alter its ice nucleation ability. Samples of kaolinite and montmorillonite, two aluminosilicate clay minerals, were treated with aqueous sulfuric and nitric acid to simulate atmospheric processing. The samples were studied X-ray diffraction, transmission electron microscopy, and inductively coupled plasma–atomic emission spectroscopy were used to study the structural changes due to acid treatment, which were correlated to observations found in ice nucleation experiments. On the basis of lattice spacing arguments, the observed reduction in ice nucleation activity of acid-treated minerals were correlated to physical and chemical alterations to the mineral structure and the formation aqueous salts on the mineral surface.