Estimating Pollution Loads in Snow Removed from a Port Facility: Snow Pile Sampling Strategies

Abstract

Choosing the appropriate sampling strategy is significant while estimating the pollutant loads in a snow pile and assessing environmental impacts of dumping snow into water bodies. This paper compares different snow pile sampling strategies, looking for the most efficient way to estimate the pollutant loads in a snow pile. For this purpose, 177 snow samples were collected from nine snow piles (average pile area − 30 m2, height − 2 m) during four sampling occasions at Frihamnen, Ports of Stockholm’s port area. The measured concentrations of TSS, LOI, pH, conductivity, and heavy metals (Zn, Cu, Cd, Cr, Pb, and V) in the collected samples indicated that pollutants are not uniformly distributed in the snow piles. Pollutant loads calculated from different sampling strategies were compared against the load calculated using all samples collected for each pile (best estimate of mass load, BEML). The results/study showed that systematic grid sampling is the best choice when the objective of sampling is to estimate the pollutant loads accurately. Estimating pollutant loads from single snow column samples (collected at a point from the snow pile through the entire depth of the pile) produced up to 400% variation from BEML, whereas samples composed by mixing volume-proportional subsamples from all samples (horizontal composite samples) produced only up to 50% variation. Around nine samples were required to estimate the pollutant loads within 50% deviation from BEML for the studied snow piles. Converting pollutant concentrations in snow to equivalent concentrations in snowmelt and comparing it with available guideline values for receiving water, Zn was identified as the critical pollutant.

Traffic-Related Metals in Urban Snow Cover: A Review of the Literature Data and the Feasibility of Filling Gaps by Field Data Collection

“…The sample collection (extraction) method mainly depends on the research objective. In this review a wide range of sampling methods were identified, such as inserting cylindrical corer sampler into the snow bank (Elik, 2001), stainless steel trowel (Glenn and Sansalone, 2002), ice drill (Reinosdotter and Viklander, 2005;Vijayan et al, 2019b), collecting (scooping) fixed volume of snow (Muthanna et al, 2007), PVC tube corer (Kuoppamäki et al, 2014), polyethylene (PE) trowels (Mihailović et al, 2014), Plexiglas corer with a removable bottom plate (Siudek et al, 2015;Pilecka et al, 2017); plastic containers (Grinfelde et al, 2021;Fournier et al, 2022), snow column sampler (Vijayan et al, 2021), aluminium snow shovel (Müller et al, 2022) for snow sampling, and for snowmelt sampling, discrete manual grab sampling (Galfi et al, 2017) and volume proportional samples withdrawn by automatic samplers (Lindfors et al, 2021). There were also differences in selection of sampling points within the snowbank, such as sampling immediately beside the road (Müller et al, 2022), or at a particular distance from the edge of road (Kuoppamäki et al, 2014;Fournier et al, 2022), at the highest point of the snowbank (Reinosdotter and Viklander, 2005), and so on.…”

“…Potential effects of the metals studied on the receiving waters vary depending on the method of snow disposal. Snow dumping into open waters (Vijayan et al, 2021), is a practice not allowed in the study area, due to its harmful effects. It represents a scenario, in which metals in snow enter the receiving waters directly and pose a threat to the aquatic environment Vijayan et al, 2021).…”

“…Snow dumping into open waters (Vijayan et al, 2021), is a practice not allowed in the study area, due to its harmful effects. It represents a scenario, in which metals in snow enter the receiving waters directly and pose a threat to the aquatic environment Vijayan et al, 2021). However, in most other disposal methods, snowmelt interacts with the surrounding environment before reaching the receiving waters and such interactions can reduce (or dilute) the concentrations and loads of metals.…”

Occurrence of Tire and Road Wear Particles in Urban and Peri-Urban Snowbanks, and Their Potential Environmental Implications

“…However, using sampling strategies where multiple samples are collected and combined to represent a larger area (multi-incremental sampling), as applied in the present study, could be important to obtain representative samples. Such strategies have been suggested in previous studies of snow (Vijayan et al, 2021) as well as for roadside soil sampling (Johnsen and Aaneby, 2019).…”

Assessment of Snowmelt Quality Discharging from a Cold-Climate Urban Landscape During Spring Melt

“…Due to the mixing of various roadside snows in removal trucks, their deposition on top of old packs, and potential-freeze thaw events causing partial or preferential elution of contaminants, it was assumed pollutants would not be uniformly distributed in the pile. Previous research on pollutant loading in snow packs found grid sampling to best minimize variations in mass load estimates(Vijayan et al 2021), though this team used drills to minimize depth uncertainty, which was not performed in the current study.The average pH for SP samples was 9.00 ± 0.54 and 8.07 ± 0.31 for SM samples (Table1). No variation was observed across either SP or SM by site or event for pH with one exception (p ≤ 0.05): the March 7th, 2020 SP samples were signi cantly different from all 2019 samples.…”