Track and trace: how aeolian dust can help to understand East African climate

Samples of present-day aeolian dust collected with the help of various kinds of dust sampling devices are currently a widely used resource to measure distinct characteristics of aeolian transported material, such as variations in the amount of dust flux over space and/or time, chemical and mineralogical composition and isotopic signatures of the material to ultimately infer the origin of the aeolian transported sediment, to understand transport pathways and to identify the sensitivity of aeolian dust to changes in local or global climate variability. However, so far the majority of samples captured by dust traps originate from classical desert environments, such as the Saharan desert or the Australian or Asian deserts. Due to smaller sample amounts, longer depositional periods, difficulties in installing the traps, and labor-intensive trap maintenance, continuous dust-trap records from semi-arid regions are rare.

In this study we present a record of aeolian dust deposits from the semi-arid region at Lake Chala, in SE Kenya/ NE Tanzania, comprising a nearly continuous sampling period of 5 years from three different locations. The first dust traps were installed in 2016 during the ICDP DeepCHALLA drilling and deliver a monthly record of dust characteristics in the area. A combination of microscopic investigations, detailed grain-size measurements, as well as mineralogical analysis allows us to infer changes in the amount and characteristics of the monthly deposited aeolian sediments and provide a first insight into seasonal changes and fluctuations of atmospheric forcing factors responsible for dust transport and the deposition in our study area.