title: Measuring solids concentrations in urban stormwater and snowmelt: a new operational procedure.
abstract: A comparative study of five methods measuring suspended sediment or solid concentrations in water-sediment mixtures indicated that, depending on the method used, broadly varying results can be obtained. For water-sediment mixtures containing sand size particles, the standard TSS method produced negatively biased results, accounting for 0 to 90% of the present solids; the negative bias directly depended on the magnitude of the sand fraction in the water-sediment mixture. The main reason for the differences between the TSS and the rest of the methods laid in the handling of samples; in the former methods, whole samples were analysed, whereas the TSS analysis was performed on sub-samples withdrawn from the water sample, the withdrawal process tending to exclude large particles. The methods using whole water-solid samples, rather than aliquots withdrawn from such samples, produced accurate estimates of solid concentrations, with a fairly good precision. Two whole-sample methods were studied in detail, a slightly modified standard SSC-B method and the newly proposed operational procedure referred to as the Multiple Filter Procedure (MFP), using three filters arranged in a series with decreasing pore sizes (25, 1.6 and 0.45 µm). Both methods assessed accurately concentrations of solids in a broad range of concentrations (200-8000 mg L(-1)) and particle sizes (0.063-4.0 mm). The newly introduced MFP was in good agreement with the SSC procedure, the differences between the two procedures not exceeding the standard bias defined for the SSC-B method. The precision of both SSC and MFP was generally better than ±10%. Consequently, these methods should be used when the total mass of transported solids is of interest.
authors: Luleå University of Technology - Civil, Environmental and Natural Resources Engineering, Luleå, Sweden. helen.galfi@ltu.se.
authors: Kerstin
authors: K
authors: Nordqvist
authors: Helen
authors: H
authors: Galfi
authors: Heléne
authors: H
authors: Osterlund
authors: Jiri
authors: J
authors: Marsalek
authors: Camilla
authors: C
authors: Westerlund
authors: Maria
authors: M
authors: Viklander
mesh_terms: D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D005374:Filtration / Q000379:methods; D019015:Geologic Sediments / Q000032:analysis; D010316:Particle Size; D011891:Rain / Q000737:chemistry*; D012914:Snow / Q000737:chemistry*; D014873:Water Pollutants / Q000032:analysis*
chemical_list: D014873:Water Pollutants