Aeolian dust in sediment: a re-examination of methods for identification and dispersal assessed by diffuse reflectance spectrophotometry

Abstract

Analyses of aeolian sediments present two main challenges: (1) when aerosol particles are collected on atmospheric filters, only a small amount of aeolian material is normally present, and (2) in these and other samples, the aeolian sediment is typically mixed with other types of particles and the aeolian material often makes up only a small percentage of the total sample. Diffuse Reflectance Spectrophotometry (DRS) holds the promise of overcoming these problems by making it possible to analyse small samples with the specificity and sensitivity needed to study materials indicative of aeolian transport. Unlike many other methods used to analyse aeolian sediments, DRS provides semi-quantitative information about mineral content which can be related to dust provenance. In this paper, we assess the effectiveness of DRS in analysing atmospheric filters from islands in the equatorial and tropical Atlantic and from desert regions in north central China. We also investigate the aeolian particles deposited on the Loess Plateau of central China, in marine sediments from the Mediterranean Sea, the Atlantic Ocean between northwest Africa and South America, and the western Pacific off Japan. As shown in these studies, DRS has become an increasingly valuable tool for the analysis of aeolian sediments, especially those containing iron oxides.