Data relating microplastics concentrations in stormwater drains to catchment land use and demographics, Perth, Western Australia
The data were collected to test hypotheses that microplastic concentrations in stormwater drains would be able to be predicted from: (1) the proportions of different land uses in stormwater catchments; (2) catchment population and land area; (3) rainfall preceding sample collection. The data show that microplastic fibres were the most common morphology across all drains, followed by fragments. Most microplastics detected were in the 100-530 µm size range, with lower proportions ≤ 25 µm or > 530 µm. The most common colour was black, followed by red, blue, and green with other colours < 5% of total particle counts. There was no statistically significant variation in microplastic concentrations between or within stormwater catchments. Linear mixed-effects models showed significant positive effects of catchment area, catchment population, and the proportion of industrial land, natural land and public open space on microplastic concentrations. The proportion of residential land had a significant negative effect on microplastic concentrations. The proportion of agricultural land in each catchment, and preceding rainfall, had no effect on microplastic concentrations. The majority of data are presented as a single comma-separated value file with 144 rows representing 3 replicates of 4 size fractions from 12 sampling sites. Samples have unique names and are categorised by Size (4 categories), Drain (6 categories) and Site (12 categories, 2 per Drain). Quantitative data relating to microplastics measurement include: sample volume; raw counts of total microplastics and microplastics separated into fragment, fibre, film, and microbead categories; concentrations of total microplastics and microplastics separated into fragment, fibre, film, and microbead categories; blank corrections (fibres only); corrected raw counts and concentrations of fibres; corrected raw counts and concentrations of total microplastics. Catchment demographic and land use data are: catchment area and population; proportions of land use in residential, industrial, services, agricultural, natural, and public open space categories. Rainfall for the 7 days prior to sample collection is also recorded. A separate comma-separated value file summarises the microplastic colour data, and an image shows aerial photograph maps of each site.
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Two sites were sampled along each of the Bayswater Main Drain, Claisebrook Main Drain, Kitchener St Drain, Osborne Park Branch Drain, South Belmont Main Drain and South Coolup Main Drain, all in the greater Perth and adjacent Peel regions, Western Australia. Water samples were filtered in-situ with a purpose-built fractionation device with samples collected on stainless steel mesh with 4 progressively increasing aperture sizes. Microplastics on each mesh were counted by optical microscopy (Nikon TE-PSE30), and blank measurements subtracted from counts. Laser Raman microscopy (WITEC Alpha 300 RA+ Confocal) was used to identify polymer types and to calculate a false positive identification rate which was then used to adjust raw, blank-subtracted counts downwards to generate the final dataset. Catchment boundaries and contributing drainage areas were derived from a hydrologically enforced digital elevation model (DEM), and land-use and population data were obtained from public domain sources.