Turnitin: Impacts of baseflow and flooding on microplastic pollution in an effluent-dependent arid land river in the USA
Abstract
Effluent discharge from wastewater treatment plants can be a substantial source of microplastics in receiving water bodies
including rivers. Despite growing concern about microplastic pollution in freshwater habitats, the literature has not yet addressed
effluent-dependent rivers, which derive 100% of their baseflow from effluent. The objective of this study was to document and
explore trends in microplastic pollution within the effluent-dependent lower Santa Cruz River near Tucson, Arizona (USA). We
examined microplastic concentrations in the water column and benthic sediment and microplastic consumption by mosquitofish
(Gambusia affinis) at 10 sites along a ~40 km stretch of the lower Santa Cruz River across two time periods: baseflow (effluent
only) and post-flood (effluent immediately following urban runoff). In total, across both sampling periods, we detected
microplastics in 95% of water column samples, 99% of sediment samples, and 6% of mosquitofish stomachs. Flow status
(baseflow vs post-flood) was the only significant predictor of microplastic presence and concentrations in our models.
Microplastic fragment concentrations in the water column were higher post-flood, microplastic fiber concentrations in benthic
sediment were lower post-flood, and mosquitofish were more likely to have consumed microplastics post-flood than during
baseflow. The additional microplastics detected after flooding was likely due to a combination of allochthonous material entering
the channel via runoff and bed scour that exhumed microplastics previously buried in the riverbed. Effluent-dependent urban
streams are becoming increasingly common; more work is needed to identify microplastic pollution baselines and trends in
effluent rivers worldwide
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- Turnitin Report [1572]