Concentrations are reported of hexabromocyclododecanes (HBCDs) and tetrabromobisphenol-A (TBBP-A) in water (n = 27), sediment (n = 9), and fish samples (n = 30) from nine English lakes. Seasonal variation in concentrations in water is minimal. Concentrations of TBBP-A range from 140 to 3200 pg L(-1) (water), 330 to 3800 pg g(-1) dry weight (sediment), and <0.29 to 1.7 ng g(-1) lipid weight (fish). Those of SigmaHBCDs range between 80 and 270 pg L(-1) (water), 880 and 4800 pg g(-1) dry weight (sediment), and 14 and 290 ng g(-1) lipid weight (fish). Aqueous concentrations of SigmaHBCDs and TBBP-A are significantly positively correlated, indicating a common source. Average +/-sigma(n) "freely-dissolved" phase proportions are 47 +/- 4.7% (SigmaHBCDs) and 61 +/- 2.9% (TBBP-A). Average field-derived bioaccumulation factors are 5900, 1300, 810, and 2100 for alpha-, beta-, gamma-, and SigmaHBCDs, respectively. Tetrabromocyclododecadienes are detected in all sediments, with pentabromocyclododecenes present in some. This suggests HBCD degrades via sequential loss of HBr. The delta-HBCD meso form was quantified in 43% of fish samples (1.0-11% SigmaHBCDs). Its absence from temporally and spatially consistent water and sediment samples suggests it is formed via bioisomerization. While HBCD chiral signatures are racemic in water and sediment, our data reveal enantiomeric enrichment of (-)alpha-HBCD and (+)gamma-HBCD in fish.
While studies on microplastics in the marine environment show their wide-distribution, persistence and contamination of biota, the freshwater environment remains comparatively neglected. Where studies on freshwaters have been undertaken these have been on riverine systems or very large lakes. We present data on the distribution of microplastic particles in the sediments of Edgbaston Pool, a shallow eutrophic lake in central Birmingham, UK. These data provide, to our knowledge, the first assessment of microplastic concentrations in the sediments of either a small or an urban lake and the first for any lake in the UK. Maximum concentrations reached 25-30 particles per 100 g dried sediment (equivalent to low hundreds kg) and hence are comparable with reported river sediment studies. Fibres and films were the most common types of microplastic observed. Spatial distributions appear to be due to similar factors to other lake studies (i.e. location of inflow; prevailing wind directions; propensity for biofouling; distribution of macroplastic debris) and add to the growing burden of evidence for microplastic ubiquity in all environments.
A radionuclide-dated ( 210 Pb and 137 Cs) sediment core collected from Hampstead Pond No. 1, a North London lake, was used to provide novel data on the historical accumulation of microplastic waste in the urban environment. Microplastics were extracted from sediments by sieving and dense-liquid separation. Fibres of anthropogenic origin dominated the assemblage. Microplastics were first identified by microscopy before Raman spectroscopy of selected particles was used to determine the composition of synthetic polymers and dyes. Polystyrene microplastic particles were identified, in addition to synthetic fibres of polyacrylonitrile, polyvinyl chloride and fibres containing synthetic dyes. Concentrations of total microplastics in the sediment samples ranged from detection level to 539 particles per kilogram of dried sediment. Proliferation of microplastics is evident in the core from the late 1950s to the present. Relatively low numbers of particles were found in older sediments, comparable to laboratory blanks, highlighting the difficulty of extending a plastic chronostratigraphy back to the early twentieth century. This study shows that, with optimisation, routine extraction of microplastics from radionuclide-dated lake sediments can add an important temporal perspective to our understanding of microplastics in aquatic systems.
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