Pollutants in urban snow
Snow and snowmelt are sources of surface water pollution, which can deteriorate the surface water quality. The major sources of pollutants in urban snow are traffic, atmospheric deposition, de-icing salt and anti-skidding materials and urban littering. The pollutants of interest in snow and snowmelt are solids, heavy metals, chlorides, organic pollutants, microplastics and nutrients.
Arya Vijayan will present her licentiate thesis titled “Quality of snow deposited in urban areas: Storage, load assessment and release of selected pollutants with snowmelt” on November 03, 2020 at Luleå University of Technology. The discussion leader is Dr. Kim H Paus from Asplan Viak AS. The overall aim of this study is to understand the concentrations and mass of pollutants in snow and pollutant’s behaviour during a melt event to support the planning and development of site-specific snow handling and management practices. The licentiate thesis consist of a study comparing different snow pile sampling designs aiming at accurately estimating the pollutant loads in the snow pile, a laboratory study to investigate the behaviour of solids, metals and PAHs during a snowmelt event and another study focusing on presence of microplastics in urban snow.
The results showed that systematic grid sampling (taking samples at regularly spaced intervals) is the best strategy compared to single snow column sampling (taking single sample vertically from top to bottom through the pile at any point in the snow pile) and composite sampling (compositing single snow column samples). The results from laboratory scale study indicate that PAHs in the urban snow are mostly attached to the particles. Only around 10% of the total PAHs burden contributed by melt water and the remaining stayed at the ground with the sediment residue. PAHs showed delayed release from snow piles, which was similar to the release pattern of TSS. Truly dissolved metals (<3000 MWCO, Molecular Weight Cut-off) (Zn, Cu and Cd) represented 71- 90% of dissolved fraction in snow samples without road salt and 74-98% in those with added road salt. Both dissolved and truly dissolved metals showed advanced release from all snow piles. Microplastics (MPs) ranging in from 50 µm to 5 mm were found in all the analysed snow samples collected from the banks of low (< 6000 vehicles/ day) and high (around 20,000 vehicles/day) traffic intensity roads. The largest proportion of MPs were road wear particle (mean 19300±47400 particles/L), which consisted of both rubber from tire and bitumen particles.
Heléne Österlund, Maria Viklander and Godecke-Tobias Blecken
Contact
Heléne Österlund
- Associate Professor
- 0920-492294
- helene.osterlund@ltu.se
- Heléne Österlund
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