Microplastic contamination of the aquatic environment is a global issue. Microplastics can be ingested by organisms leading to negative physiological impacts. The ingestion of microplastics by ...freshwater invertebrates has not been reported outside the laboratory. Here we demonstrate the ingestion of microplastic particles by Tubifex tubifex from bottom sediments in a major urban waterbody fed by the River Irwell, Manchester, UK. The host sediments had microplastic concentrations ranging from 56 to 2543 particles kg–1. 87% of the Tubifex-ingested microplastic particles were microfibers (55–4100 μm in length), while the remaining 13% were microplastic fragments (50–4500 μm in length). FT-IR analysis revealed ingestion of a range of polymers, including polyester and acrylic fibers. While microbeads were present in the host sediment matrix, they were not detected in Tubifex worm tissue. The mean concentration of ingested microplastics was 129 ± 65.4 particles g–1 tissue. We also show that Tubifex worms retain microplastics for longer than they retain other particulate components of the ingested sediment matrix. Microplastic ingestion by Tubifex worms poses a significant risk for trophic transfer and biomagnification of microplastics up the aquatic food chain.
Across a 1000‐km stretch of the River Nile, from the 1st Cataract in southern Egypt to the 4th Cataract in Sudan, many hundreds of drystone walls are located within active channels, on seasonally ...inundated floodplains or in now‐dry Holocene palaeochannel belts. These walls (or river groynes) functioned as flood and flow control structures and are of a type now commonly in use worldwide. In the Nile Valley, the structures have been subject only to localised investigations, and none have been radiometrically dated. Some were built within living memory to trap nutrient‐rich Nile silts for agriculture, a practice already recorded in the early 19th century C.E. However, others situated within ancient palaeochannel belts indicate construction over much longer time frames. In this paper, we map the distribution of these river groynes using remote sensing and drone survey. We then establish their probable functions and a provisional chronology using ethnoarchaeological investigation and the ground survey, excavation and radiometric dating of the structures in northern Sudan, focusing on the Holocene riverine landscape surrounding the pharaonic settlement of Amara West (c. 1300–1000 B.C.E.). Finally, we consider the historical and economic implications of this form of hydraulic engineering in the Nile Valley over the past three millennia.
Purpose
Manchester is often heralded as the first industrial city. Large volumes of physical and liquid contaminants were released into its river network throughout the industrial period up to the ...latter part of the twentieth century. Water quality has improved dramatically in recent decades, but, given their environmental significance, it is important to ascertain the extent to which a legacy of contamination persists in the modern bed sediments.
Materials and methods
Fine-grained bed sediments were sampled at 40 sites in the Mersey and Irwell catchments. Sediments were wet sieved to isolate the <63-μm grain size fraction. Metal concentrations were determined using XRF. Particle size characteristics were also measured. Sediments were subjected to a five-step sequential extraction procedure to ascertain the environmental significance of metal concentrations. Alongside archival research of past industry, enrichment factors, multivariate statistical techniques and conditional inferences trees were used to identify sources of heavy metals.
Results and discussion
Bed sediment-associated heavy metal(loid) concentrations were as follows: As (9.89–110 mg kg
−1
), Cr (76.5–413 mg kg
−1
), Cu (53.1–383 mg kg
−1
), Pb (80.4–442 mg kg
−1
) and Zn (282–1020 mg kg
−1
). Enrichment factors ranged from moderate to extremely severe, with Pb showing the greatest enrichment across the catchments. Chemical mobility was generally low, but metal(loid) partitioning identified the influence of anthropogenic sources. Statistical analysis highlighted a number of point sources associated with former industrial sites that operated during the industrial period. Conditional inference trees highlighted the role of the textile industry on Cu concentrations in addition to indicating the complexity of sources, fluxes and stores of sediment-associated contamination throughout the system.
Conclusions
Fine-grained sediment-associated metal(loid)s in the Mersey and Irwell catchments are anthropogenically enriched. Concentrations also exceed sediment quality guidelines. A lack of distinct spatial patterning points to a complex network of contaminant inputs across the catchments, even in the headwaters. Whilst potential modern urban sources are likely to be important, spatial patterns and multivariate/data mining techniques also highlighted the importance of releases from former industrial sites as well as the reworking of historically contaminated floodplains and soils.
This paper outlines the nature of microplastic contamination in rivers and the risks to freshwater fishes. We discuss how input sources influence the concentration and composition of microplastics ...and examine factors that subsequently influence their spatiotemporal dynamics in a river system. We then discuss how the distributions and assemblages of microplastics can impact the risk of interactions with fishes, and the processes associated with the internalisation of microplastic into the body and across the organs and tissues. Finally, we examine the physical and toxicological effects of microplastic exposure in fish species, with special attention directed towards impacts at environmentally relevant concentrations. This review integrates expertise in fluvial geomorphological processes and how they influence the movement and storage of microplastics in river channel environments at a range of scales. We combine this knowledge with expertise in fish ecology and biology to set out a new and integrated analysis of microplastic dynamics in rivers and how these microplastics interact with fish. The integration of knowledge from these fields allows us also to comment upon the microplastic risk to fish and other biota in river environments.
•We explore current understanding of riverine microplastics and their interactions with freshwater fish.•We examine how sources of microplastics combine with fluvial processes to influence their fate in a river system.•We review microplastic bioavailability, uptake, retention and removal, bioaccumulation, biomagnification, and translocation.•We consider the physical and toxicological effects of microplastic exposure in fish with special attention at environmentally-relevant concentrations.
On December 26, 2015 (Boxing Day), an exceptional flood event occurred in the Irwell catchment, United Kingdom, when the neighbouring Mersey catchment experienced a much more typical winter run‐off ...event. This provided an opportunity to examine the influence of high‐magnitude hydrological processes on the behaviour of fine‐grained metal‐contaminated bed sediments. Forty sites across the two catchments were sampled for channel bed fine sediment storage and sediment‐associated metal(loid) concentrations prior to, and following, the flooding. Sediments were analysed for total As, Cr, Cu, Pb, and Zn and then subjected to a five‐step sequential extraction procedure. Despite a significant reorganisation of fine‐grained (<63 μm) sediment storage, metal(loid) concentrations demonstrated markedly conservative behaviour with no significant difference observed between pre‐flooding and post‐flooding values across both catchments. Estimates of the channel bed storage of sediment‐associated metal(loid)s also showed minimal change as a result of the flooding. The metal partitioning data reveal only minor changes in the mobility of bed sediment‐associated metal(loid)s, indicating that such flood events do not increase the availability of sorbed contaminants in these catchments. Post‐flooding bed sediment metal(loid) loadings remain high, indicating persistent and long‐lasting sources of contamination within the Irwell and upper Mersey fluvial network.
Past human mountain settlement patterns and resource and high-altitude landscape exploitation are underexplored research fields in archaeology. This study presents data gathered during more than 20 ...years of fieldwork in the Pindus range of Western Macedonia (Greece), focusing in particular on Holocene land use. The investigated territory is located around the Vlach town of Samarina. The area is partly bounded by Mounts Vasilitsa, Gurguliu, Bogdani and Anitsa, and their interconnecting watersheds between ca. 1400 and 2000 m a.s.l. This research led to the discovery of many sites and findspots of lithic and ceramic artefacts attributed to the Middle and Upper Palaeolithic, Mesolithic, Late Neolithic, Chalcolithic, Bronze Age, and several Historical periods. The radiocarbon results show an unexpected longue durée of Holocene human landscape use. The number of sites, their distribution, location, and subsistence strategies exhibit shifts between the Middle Palaeolithic and different periods of the Holocene, which are closely related to the exploitation of the mountain environment and its resources. Moreover, typical knapped stone artefacts have been used as a proxy for dating the glacial landforms which characterise the Samarina highland zone; we correlate them to the better-known moraine systems of Mount Tymphi in Epirus and contribute to the reconstruction of the Pleistocene glacial landscapes of the Pindus Range.
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