Microplastics in Lake Mead National Recreation Area, USA: Occurrence and biological uptake

Abstract

Microplastics are an environmental contaminant of growing concern, but there is a lack of information about microplastic distribution, persistence, availability, and biological uptake in freshwater systems. This is especially true for large river systems like the Colorado River that spans multiple states through mostly rural and agricultural land use. This study characterized the quantity and morphology of microplastics in different environmental compartments in two large reservoirs along the Colorado River: Lakes Mead and Mohave, within Lake Mead National Recreation Area. To assess microplastic occurrence, surface water and surficial sediment were sampled at a total of nine locations. Sampling locations targeted different sub-basins with varying levels of anthropogenic impact. Las Vegas Wash, a tributary which delivers treated wastewater to Lake Mead, was also sampled. A sediment core (33 cm long, representing approximately 19 years) was extracted from Las Vegas Bay to assess changes in microplastic deposition over time. Striped bass (Morone saxatilis), common carp (Cyprinus carpio), quagga mussels (Dreissena bugensis), and Asian clams (Corbicula fluminea) were sampled at a subset of locations to assess biological uptake of microplastics. Microplastic concentrations were 0.44-9.7 particles/cubic meter at the water surface and 87.5-1,010 particles/kilogram dry weight (kg dw) at the sediment surface. Sediment core concentrations were 220-2,040 particles/kg dw, with no clear increasing or decreasing trend over time. Shellfish microplastic concentrations ranged from 2.7-105 particles/organism, and fish concentrations ranged from 0-19 particles/organism. Fibers were the most abundant particle type found in all sample types. Although sample numbers are small, microplastic concentrations appear to be higher in areas of greater anthropogenic impact. Results from this study improve our understanding of the occurrence and biological uptake of microplastics in Lake Mead National Recreation Area, and help fill existing knowledge gaps on microplastics in freshwater environments in the southwestern U.S.

Use of the Zebra Mussel Dreissena polymorpha (Mollusca, Bivalvia) as a Bioindicator of Microplastics Pollution in Freshwater Ecosystems: A Case Study from Lake Iseo (North Italy)

“…There were significant differences in the shape frequencies between the three sites (χ 2 = 8.095; chi-square test, p = 0.017). As reported by previous studies of microplastics pollutions in freshwater environments [34][35][36][37], we noted that fibers were the most abundant microplastic found in the samples from all three sites, whereas fragments were more commonly found in the samples from the sites (Costa Volpino and Lovere) with greater anthropogenic impact due to their proximity to wastewater inflow, as reported elsewhere [37].…”

“…The chi-square test showed significant differences in the color frequencies between the three sites (χ 2 = 20.14; p = 0.002). The source of the blue particles is unclear, but their prevalence has been reported in previous studies [37,38].…”

“…Field studies of microplastics accumulation in zebra mussels are lacking. A study in quagga mussels (Dreissena bugensis) from Lake Mead and Lake Mohave in the Lake Mead National Recreation Area (USA) found higher items/specimens (range, 2.7-13.0) [37]. As regards other freshwater bivalve species, Su et al [38] conducted a survey of microplastic pollution in Asian clams (Corbicula fluminea) from 21 sites in the Middle-Lower Yangtze River Basin and found microplastics at a concentration of 0.4-5.0 items/individual.…”

Electric clothes dryers: An underestimated source of microfiber pollution

“…An abundance of microfibers have been found in aquatic (freshwater and marine) and terrestrial environments worldwide [7][8][9][10][11]. Recent studies have observed microplastics, the majority of which were microfibers, in the French Pyrenees, the Italian Alps and in snow samples from the Arctic [12,13].…”

Lake Phytoplankton Assemblage Altered by Irregularly Shaped PLA Body Wash Microplastics but Not by PS Calibration Beads

“…Fibers are therefore more likely to interact with living cells that they encounter in the environment than beads and fragments. With our increasing awareness of their true ubiquity [9,23,58], further investigation of the effects of MPs, including fibers on phytoplankton communities, and potential bottom-up effects on aquatic food webs are warranted.…”