Microplastics are ubiquitous contaminants in aquatic habitats globally, and wastewater treatment plants (WWTPs) are point sources of microplastics. Within aquatic habitats microplastics are colonized ...by microbial biofilms, which can include pathogenic taxa and taxa associated with plastic breakdown. Microplastics enter WWTPs in sewage and exit in sludge or effluent, but the role that WWTPs play in establishing or modifying microplastic bacterial assemblages is unknown. We analyzed microplastics and associated biofilms in raw sewage, effluent water, and sludge from two WWTPs. Both plants retained >99% of influent microplastics in sludge, and sludge microplastics showed higher bacterial species richness and higher abundance of taxa associated with bioflocculation (e.g. Xanthomonas) than influent microplastics, suggesting that colonization of microplastics within the WWTP may play a role in retention. Microplastics in WWTP effluent included significantly lower abundances of some potentially pathogenic bacterial taxa (e.g. Campylobacteraceae) compared to influent microplastics; however, other potentially pathogenic taxa (e.g. Acinetobacter) remained abundant on effluent microplastics, and several taxa linked to plastic breakdown (e.g. Klebsiella, Pseudomonas, and Sphingomonas) were significantly more abundant on effluent compared to influent microplastics. These results indicate that diverse bacterial assemblages colonize microplastics within sewage and that WWTPs can play a significant role in modifying the microplastic-associated assemblages, which may affect the fate of microplastics within the WWTPs and the environment.
Abstract
The ecological dynamics of microplastic (<5 mm) are well documented in marine ecosystems, but the sources, abundance, and ecological role of microplastic in rivers are unknown and likely to ...be substantial. Microplastic fibers (e.g., synthetic fabrics) and pellets (e.g., abrasives in personal care products) are abundant in wastewater treatment plant (
WWTP
) effluent, and can serve as a point source of microplastic in rivers. The buoyancy, hydrophobic surface, and long transport distance of microplastic make it a novel substrate for the selection and dispersal of unique microbial assemblages. We measured microplastic concentration and bacterial assemblage composition on microplastic and natural surfaces upstream and downstream of
WWTP
effluent sites at nine rivers in Illinois, United States. Microplastic concentration was higher downstream of
WWTP
effluent outfall sites in all but two rivers. Pellets, fibers, and fragments were the dominant microplastic types, and polymers were identified as polypropylene, polyethylene, and polystyrene. Mean microplastic flux was 1,338,757 pieces per day, although the flux was highly variable among nine sites (min = 15,520 per day, max = 4,721,709 per day). High‐throughput sequencing of 16S
rRNA
genes showed bacterial assemblage composition was significantly different among microplastic, seston, and water column substrates. Microplastic bacterial assemblages had lower taxon richness, diversity, and evenness than those on other substrates, and microplastic selected for taxa that may degrade plastic polymers (e.g.,
Pseudomonas
) and those representing common human intestinal pathogens (e.g.,
Arcobacter
). Effluent from
WWTP
s in rivers is an important component of the global plastic “life cycle,” and microplastic serves as a novel substrate that selects and transports distinct bacterial assemblages in urban rivers. Rates of microplastic deposition, consumption by stream biota, and the metabolic capacity of microplastic biofilms in rivers are unknown and merit further research.
Rivers are a major source of microplastic particles (<5 mm) to oceans, but empirical measurements of microplastic movement in freshwater ecosystems are rare. The hard, buoyant surface of microplastic ...is a novel habitat that selects for unique microbial assemblages in rivers, especially downstream of wastewater treatment plant (WWTP) point sources. We measured microplastic in surface water and benthic habitats 50 m upstream and 50, 305, 1115, and 1900 m downstream of the effluent outfall from a large WWTP in an urban river. We used high-throughput sequencing to measure bacterial assemblages on microplastic from surface and benthic habitats and compared them to bacterial assemblages from seston, water, and sediment. Concentrations of total microplastic and microplastic types (fragment, pellet) in surface water did not change with distance downstream of the WWTP. Thus, microplastic transport showed no net deposition or resuspension. Microplastic concentrations were much higher in the benthic zone than surface water. Benthic deposition appears to be a plastic sink over longer time scales, but subsequent studies are needed to resolve microplastic transport dynamics by particle type, size, and habitat. Composition of microplastic-attached bacterial assemblages differed from that of assemblages in water, seston, and sediment and supports domestic wastewater as a point source of microplastic (e.g., gastrointestinal taxa). Shifts in microplastic assemblages with distance from the WWTP suggest succession toward a ‘stream-like’ bacterial assemblage. Future studies are required to quantify the metabolic capacity of microplastic-associated bacteria. Estimates of transport distance, microplastic storage, and microbial interactions are critical to include lotic ecosystems in accountings of global plastic budgets.
SMU 76938 is a nearly complete skeleton of a fossil bony fish, about 1.2 m in total length, housed in Southern Methodist University in Dallas, Texas, USA. It was collected from the Tarrant Formation ...(middle Cenomanian) of the Upper Cretaceous Eagle Ford Group in Tarrant County, Texas, an area where it was near the East Texas Embayment of the Western Interior Seaway during the Late Cretaceous. Our phylogenetic analysis indicates that it is a pachyrhizodontid crossognathiform fish, and comparisons with previously reported pachyrhizodontids suggest that the fossil fish belongs to a new genus and species within Pachyrhizodontidae, Polcynichthys lloydhilli gen. et sp. nov.. With a fusiform body, a large symmetrical caudal fin, and a mouth with numerous small conical teeth suited for grasping, the new taxon is interpreted to be a fast swimming, open-ocean predator that likely pursued smaller squid, crustaceans, and other fishes. Vertebral growth rings suggest that the individual was possibly about 14 years old at the time of its death, and our vertebra-based theoretical growth model indicates that the species could have reached up to about 1.8 m TL and lived up to 37 years old in age.
Microplastic is a contaminant of concern in freshwater ecosystems worldwide. Microplastic particles within aquatic habitats are colonized by dense microbial biofilms, and previous studies have shown ...that microplastic microbiomes are distinct in taxonomic composition from bacterial assemblages in the surrounding environment. However, questions remain about the degree to which microplastic selects for specific bacterial taxa across diverse aquatic habitats. We used laboratory microcosms inoculated with water from 3 rivers in northern Illinois watersheds with distinct land-use types to test the hypothesis that microbiomes present on microplastic would be similar even when the microplastic was incubated with microbial assemblages from different source waters. When microplastic from a commercial soap and ceramic tiles were incubated with water from each of the 3 rivers for ~1 mo, the bacterial assemblages that colonized the microplastic were remarkably consistent in taxonomic composition, whereas the planktonic and tile bacterial assemblages originating from the 3 rivers were distinct. The number of bacterial operational taxonomic units found within the microplastic microbiomes was consistent across source water treatments and ~3× lower than in the surrounding water and tiles. Some of the bacterial taxa that were over-represented in the microplastic microbiomes in our experiment can metabolize plastic or plastic-associated compounds. If microplastic microbiomes are metabolizing plastic polymers, this process could have significant implications for the long-term fate of microplastic in freshwater habitats.
Palaeonotopterus greenwoodi Forey is an enigmatic Cretaceous bony fish (Teleostei: Osteoglossomorpha) currently known only from Albian–Cenomanian deposits of Morocco. Here, we describe nine fossil ...tooth plate specimens from the Eutaw Formation and Mooreville Chalk Formation from Alabama, U.S.A., tentatively assigned to P. greenwoodi. If they indeed belong to the taxon, these specimens not only represent the geologically youngest material ranging from late Santonian to early Campanian in age, but also constitute the first record of the species outside of Morocco.
Colorectal cancer often presents with obstruction needing urgent, potentially life-saving decompression. The comparative efficacy and safety of endoluminal stenting versus emergency surgery as ...initial treatment for such patients is uncertain.
Patients with left-sided colonic obstruction and radiological features of carcinoma were randomized to endoluminal stenting using a combined endoscopic/fluoroscopic technique followed by elective surgery 1-4 weeks later, or surgical decompression with or without tumour resection. Treatment allocation was via a central randomization service using a minimization procedure stratified by curative intent, primary tumour site, and severity score (Acute Physiology And Chronic Health Evaluation). Co-primary outcome measures were duration of hospital stay and 30-day mortality. Secondary outcomes were stoma formation, stenting completion and complication rates, perioperative morbidity, 6-month survival, 3-year recurrence, resource use, adherence to chemotherapy, and quality of life. Analyses were undertaken by intention to treat.
Between 23 April 2009 and 22 December 2014, 245 patients from 39 hospitals were randomized. Stenting was attempted in 119 of 123 allocated patients (96.7 per cent), achieving relief of obstruction in 98 of 119 (82.4 per cent). For the 89 per cent treated with curative intent, there were no significant differences in 30-day postoperative mortality (3.6 per cent (4 of 110) versus 5.6 per cent (6 of 107); P = 0.48), or duration of hospital stay (median 19 (i.q.r. 11-34) versus 18 (10-28) days; P = 0.94) between stenting followed by delayed elective surgery and emergency surgery. Among patients undergoing potentially curative treatment, stoma formation occurred less frequently in those allocated to stenting than those allocated to immediate surgery (47 of 99 (47.5 per cent) versus 72 of 106 (67.9 per cent); P = 0.003). There were no significant differences in perioperative morbidity, critical care use, quality of life, 3-year recurrence or mortality between treatment groups.
Stenting as a bridge to surgery reduces stoma formation without detrimental effects. Registration number: ISRCTN13846816 (http://www.controlled-trials.com).
The variable line spacing plane grating monochromator beamline at the Canadian Light Source (CLS) employs three grazing incidence variable line spacing gratings to cover a photon energy range of ...5-250 eV. It uses a 185 mm period length planar permanent magnet insertion device as the photon source, sharing a straight section with another soft x-ray beamline at the CLS. The commissioning and performance of the beamline is reported. The high resolution photoabsorption spectra of Ar and PF(5) gases are reported. A resolving power of over 40,000 for photons in the low energy region and >10,000 for a wider energy range (8-200 eV) can be achieved. A photon flux of up to 2 x 10(12) photons/s per 100 mA with slit settings of 50 microm has been measured.
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