Microplastics (plastic < 5 mm in size) are now known to contaminate riverine systems but understanding about how their concentrations vary spatially and temporally is limited. This information is ...critical to help identify key sources and pathways of microplastic and develop management interventions. This study provides the first investigation of microplastic abundance, characteristics and temporal variation along the Ganges river; one of the most important catchments of South Asia. From 10 sites along a 2575 km stretch of the river, 20 water samples (3600 L in total) were filtered (60 samples each from pre- and post-monsoon season). Overall, 140 microplastic particles were identified, with higher concentrations found in the pre-monsoon (71.6%) than in post-monsoon (61.6%) samples. The majority of microplastics were fibres (91%) and the remaining were fragments (9%). We estimate that the Ganges, with the combined flows of the Brahmaputra and Meghna rivers (GBM), could release up to 1–3 billion (109) microplastics into the Bay of Bengal (north-eastern portion of the Indian Ocean) every day. This research provides the first step in understanding microplastic contamination in the Ganges and its contribution to the oceanic microplastic load.
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•The microplastics identified were dominated by fibers (91%) and fragments (9%).•A greater number of microplastics were found pre-monsoon than post-monsoon•Microplastic concentrations increased from source to sea.•Approximately 1–3 billion microplastic pieces are discharged into the Bay of Bengal daily.
We estimate that up to 1–3 billion microplastics are released into the Bay of Bengal every day.
The washing of synthetic clothes is considered to be a substantial source of microplastic to the environment. Therefore, various devices have been designed to capture microfibres released from ...clothing during the washing cycle. In this study, we compared 6 different devices which varied from prototypes to commercially available products. These were designed to either be placed inside the drum during the washing cycle or fitted externally to filter the effluent wastewater discharge. The aim of this study was to examine the efficacy of these devices at mitigating microfibre release from clothing during washing or at capturing any microfibres released in the wastewater. When compared to the amount of microfibres entering the wastewater without any device (control), the XFiltra filter was the most successful device. This device captured microfibres reducing their release to wastewater by around 78%. The Guppyfriend bag was the second most successful device, reducing microfibre release to wastewater by around 54%; it appeared to mainly work by reducing microfibre shedding from the clothing during the washing cycle. Despite some potentially promising results it is important to recognise that fibres are also released when garments are worn in everyday use. Researchers and industry need to continue to collaborate to better understand the best intervention points to reduce microfibre shedding, by considering both product design and fibre capture.
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•This study tested the efficiency of six devices available in 2018.•XFiltra was 78% efficient at reducing microfibre loss to wastewater.•External filters were more successful at microfibre capture.•In-drum inventions helped reduce microfibre release from clothing itself.•Independent research is essential to establish optimum intervention points.
While land-based sources of plastic pollution have gained increasing attention in recent years, ocean-based sources have been less well studied. The aim of this study was to compare a variety of ...ropes (differing in age, wear surface and material) to quantify and characterise the production of microplastic during use. This was achieved by simulating, in laboratory and field experiments, rope hauling activity which is typically performed on board maritime vessels, such as fishing boats. Microplastic generation was quantified by collecting fragments that were released as a consequence of abrasion. Notably, we show that microplastic fragments generated from rope wear during use were characteristically irregular in shape, rather than fibrous such as those assigned to synthetic rope by previous studies. Therefore, we suggest that some of the plastic fragments found in the marine environment may have been falsely attributed to land-based sources but have in fact arisen form the abrasion of rope. Our research found that new and one-year old polypropylene rope released significantly fewer microplastic fragments (14 ± 3 and 22 ± 5) and less microplastic mass (11 ± 2 and 12 ± 3 μg) per metre hauled compared to ropes of two (720 ± 51, 247 ± 18 μg) or ten (767 ± 55, 1052 ± 75 μg) years of age. We show that a substantial amount of microplastic contamination is likely to directly enter the marine environment due to in situ rope abrasion and that rope age is an important factor influencing microplastic release. Our research suggests the need for standards on rope maintenance, replacement, and recycling along with innovation in synthetic rope design with the aim to reduce microplastic emission.
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•This study tested a variety of ropes differing in age and polymer type.•Microplastic from rope abrasion is likely to directly enter the marine environment.•Microplastic fragments, not fibres, were generated from rope wear.•New rope released significantly less microplastic fragments than older rope (≥ 2 yrs).•Need for standards on rope maintenance, replacement and recycling.
Rivers are key pathways for the transfer of microplastics (MP) to marine environments. However, there are considerable uncertainties about the amount of microplastics transported by rivers to the ...ocean; this results in inaccuracies in our understanding of microplastic quantity and transport by freshwater systems. Additionally, it has been suggested that rivers may represent long-term sinks, with microplastics accumulating in sediment due to their high density or other biological, chemical, and physical factors. The atmosphere is also an important pathway by which airborne microplastics may enter aquatic habitats. Here, we compare for first time microplastics type and concentration in these key environmental mediums (air, water and sediment) along a major river (Ganges), from sea to source to understand 1) the abundance, 2) the spatial distribution, and 3) characteristics. Mean microplastic abundance settling from the atmosphere was 41.12 MP m−2 day−1; while concentrations in sediment were 57.00 MP kg−1 and in water were 0.05 MP L−1. Across all sites and environmental mediums, rayon (synthetically altered cellulose) was the dominant polymer (54–82 %), followed by acrylic (6–23 %) and polyester (9–17 %). Fibres were the dominant shape (95–99 %) and blue was the most common colour (48–79 %). Across water and sediment environmental mediums, the number of microplastics per sample increased from the source of the Ganges to the sea. Additionally, higher population densities correlated with increased microplastic abundance for air and water samples. We suggest that clothing is likely to be the prominent source of microplastics to the river system, influenced by atmospheric deposition, wastewater and direct input (e.g. handwashing of clothes in the Ganges), especially in high density population areas. However, we suggest that subsequent microplastic release to the marine environment is strongly influenced by polymer type and shape, with a large proportion of denser microplastics settling in sediment prior to the river discharging to the ocean.
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•Microplastics were investigated in water, sediment, and air in a major river system for the first time.•For water and sediment there was an increase of microplastics from source to sea.•Higher population densities correlated with increased microplastic abundance in Air and Water.•It is predicted a large proportion of denser microplastics settle in sediment.•Rayon was the dominant polymer and blue fibres were the dominant colour and shape.
West Nile virus (WNV) has been maintained in North America in enzootic cycles between mosquitoes and birds since it was first described in North America in 1999. House sparrows (HOSPs; Passer ...domesticus) are a highly competent host for WNV that have contributed to the rapid spread of WNV across the U.S.; however, their competence has been evaluated primarily using an early WNV strain (NY99) that is no longer circulating. Herein, we report that the competence of wild HOSPs for the NY99 strain has decreased significantly over time, suggesting that HOSPs may have developed resistance to this early WNV strain. Moreover, recently isolated WNV strains generate higher peak viremias and mortality in contemporary HOSPs compared to NY99. These data indicate that opposing selective pressures in both the virus and avian host have resulted in a net increase in the level of host competence of North American HOSPs for currently circulating WNV strains.
The distribution of West Nile virus has expanded in the past 6 years to include the 48 contiguous United States and seven Canadian provinces, as well as Mexico, the Caribbean islands, and Colombia. ...The suggestion of the emergence of a dominant genetic variant has led to an intensive analysis of isolates made across North America. We have sequenced the premembrane and envelope genes of 74 isolates and the complete genomes of 25 isolates in order to determine if a dominant genotype has arisen and to better understand how the virus has evolved as its distribution has expanded. Phylogenetic analyses revealed the continued presence of genetic variants that group in a temporally and geographically dependent manner and provide evidence that a dominant variant has emerged across much of North America. The implications of these findings are discussed as they relate to transmission and spread of the virus in the Western Hemisphere.
A West Nile virus (WNV) isolate from Mexico (TM171-03) and BIRD1153, a unique genotype from Texas, have exhibited reduced murine neuroinvasive phenotypes. To determine if murine neuroinvasive ...capacity equates to avian virulence potential, American crow (Corvus brachyrhynchos) and house sparrows (Passer domesticus) were experimentally inoculated with representative murine neuroinvasive/non-neuroinvasive strains. In both avian species, a plaque variant from Mexico that was E-glycosylation competent produced higher viremias than an E-glycosylation-incompetent variant, indicating the potential importance of E-glycosylation for avian replication. The murine non-neuroinvasive BIRD1153 strain was significantly attenuated in American crows but not house sparrows when compared with the murine neuroinvasive Texas strain. Despite the loss of murine neuroinvasive properties of nonglycosylated variants from Mexico, our data indicate avian replication potential of these strains and that unique WNV virulence characteristics exist between murine and avian models. The implications of reduced avian replication of variants from Mexico for restricted WNV transmission in Latin America is discussed.
The hallmark attribute of North American West Nile virus (WNV) strains has been high pathogenicity in certain bird species. Surprisingly, this avian virulent WNV phenotype has not been observed ...during its geographical expansion into the Caribbean, Central America and South America. One WNV variant (TM171-03-pp1) isolated in Mexico has demonstrated an attenuated phenotype in two widely distributed North American bird species, American crows (AMCRs) and house sparrows (HOSPs). In order to identify genetic determinants associated with attenuated avian replication of the TM171-03-pp1 variant, chimeric viruses between the NY99 and Mexican strains were generated, and their replicative capacity was assessed in cell culture and in AMCR, HOSP and house finch avian hosts. The results demonstrated that mutations in both the pre-membrane (prM-I141T) and envelope (E-S156P) genes mediated the attenuation phenotype of the WNV TM171-03-pp1 variant in a chicken macrophage cell line and in all three avian species assayed. Inclusion of the prM-I141T and E-S156P TM171-03-pp1 mutations in the NY99 backbone was necessary to achieve the avian attenuation level of the Mexican virus. Furthermore, reciprocal incorporation of both prM-T141I and E-P156S substitutions into the Mexican virus genome was necessary to generate a virus that exhibited avian virulence equivalent to the NY99 virus. These structural changes may indicate the presence of new evolutionary pressures exerted on WNV populations circulating in Latin America or may signify a genetic bottleneck that has constrained their epiornitic potential in alternative geographical locations.
Complete genome sequencing of 22 West Nile virus isolates suggested 2 independent introductions into Mexico. A previously identified mouse-attenuated glycosylation variant was introduced into ...southern Mexico through the southeastern United States, while a common US genotype appears to have been introduced incrementally into northern Mexico through the southwestern United States.
West Nile virus (WNV) has been maintained in North America in enzootic cycles between mosquitoes and birds since it was first described in North America in 1999. House sparrows (HOSPs; Passer ...domesticus) are a highly competent host for WNV that have contributed to the rapid spread of WNV across the U.S.; however, their competence has been evaluated primarily using an early WNV strain (NY99) that is no longer circulating. Herein, we report that the competence of wild HOSPs for the NY99 strain has decreased significantly over time, suggesting that HOSPs may have developed resistance to this early WNV strain. Moreover, recently isolated WNV strains generate higher peak viremias and mortality in contemporary HOSPs compared to NY99. These data indicate that opposing selective pressures in both the virus and avian host have resulted in a net increase in the level of host competence of North American HOSPs for currently circulating WNV strains.
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