Dark microplastics trigger changes on snow metamorphism that depends on the snow initial density

Area of Science:

• Environmental Science
• Glaciology
• Atmospheric Science

Background:

• Microplastic pollution is pervasive, even in cryospheric regions.
• The impact of microplastics on snow albedo and melting remains largely uninvestigated.
• Dark microplastics can act as light-absorbing impurities.

Purpose of the Study:

• To assess the effect of dark microplastics on snow properties under realistic conditions.
• To investigate the relationship between microplastic concentration and changes in snow albedo, specific surface area, and melt rate.

Main Methods:

• Conducted six in situ experiments in the Central Pyrenees (Spain).
• Exposed surface snow to varying concentrations of dark microplastics for 4 hours.
• Monitored changes in snow albedo, specific surface area, and snowmelt.

Main Results:

• Results varied significantly based on initial snow conditions (density and age).
• In light snow (<250 kg m^-3), microplastics caused moderate albedo decrease and significant specific surface area reduction (11.4 m² kg^-1), with minimal melt (<1%).
• In aged, dense snow (>450 kg m^-3), high microplastic loads increased snowmelt by 17% compared to control samples.

Conclusions:

• Dark microplastics have a variable impact on snow properties, contingent on snow characteristics.
• Further research is crucial to fully understand microplastic effects on the global cryosphere.
• Microplastics can alter snowmelt dynamics, with implications for hydrological cycles and climate feedbacks.