Type of precipitation and durations of sediment exposure as important weathering factors

Abstract

A diversity of factors, led by lithology, weathering, and erosion processes, plays a significant role in the formation and future of badland terrains. Then on previous observations it can be concluded that surface flow processes are the first trigger of erosion and that intense soil erosion combined with rapid and deep weathering are tightly connected to high erosion rates.

Since climate change presents a global issue that gains increasing attention and due to the complexity of the interactions and processes that are a part of general badlands origin and evolution, a weathering experiment on badland sediments from China was conducted. Explaining temporal changes, the impact of different precipitation types and its durations of exposure on sediments during weathering processes, as well as its impact on leachate ions behaviour are the aims behind this experiment.

Red clayey siltstone and mudstone badland sediments selected for the laboratory experiment were organized in four sets that included three different samples, making a total of 12 treated samples. Based on field climate data, in laboratory conditions samples were exposed to rain, acid rain, snow, and acid snow through fifteen daily cycles. Leachate was collected after each cycle and its volume, pH, electrical conductivity (EC), and ion concentrations were measured and analysed from the leachate. Changes occurring on the surface of the sample were observed through photographs taken at the end of each cycle. Based on obtained results it can be said that the main differences occur when comparing rain and snow treatments generally. Temporal, cyclic changes were, to a certain extent, noticed through sediment decay. More importantly, durations of sediment exposure to precipitation proved to be crucial for weathering processes of tested siltstones and mudstones, having exclusion and ionic forces - ion exchange chromatography as dominant chemical processes.