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Issue Indigenous women in many countries experience a lack of access to culturally appropriate midwifery services. A number of models of care have been established to provide services to women. Research has examined some services, but there has not been a synthesis of qualitative studies of the models of care to help guide practice development and innovations. Aim To undertake a review of qualitative studies of midwifery models of care for Indigenous women and babies evaluating the different types of services available and the experiences of women and midwives. Methods A meta-synthesis was undertaken to examine all relevant qualitative studies. The literature search was limited to English-language published literature from 2000–2014. Nine qualitative studies met the inclusion criteria and literature appraisal – six from Australia and three from Canada. These articles were analysed for coding and theme development. Findings The major themes were valuing continuity of care, managing structural issues, having negative experiences with mainstream services and recognising success. Discussion The most positive experiences for women were found with the services that provided continuity of care, had strong community links and were controlled by Indigenous communities. Overall, the experience of the midwifery services for Indigenous women was valuable. Despite this, there were still barriers preventing the provision of intrapartum midwifery care in remote areas. Conclusion The expansion of midwifery models of care for Indigenous women and babies could be beneficial in order to improve cultural safety, experiences and outcomes in relation to pregnancy and birth. [ABSTRACT FROM AUTHOR]

Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. In Humber Bay and Toronto Harbour microplastic concentrations were consistently > 500 particles per kg dry sediment. Maximum concentrations of ~ 28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments < 2 mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring and discuss potential sources of microplastics in terms of how and where to implement preventative measures to reduce the contaminant influx. Although the impacts of microplastics contamination on ecosystem health and functioning is uncertain, understanding, monitoring and preventing further microplastics contamination in Lake Ontario and the other Great Lakes is crucial. [ABSTRACT FROM AUTHOR]

Microplastics (plastic particles <5 mm) are abundant in aquatic environments, particularly near urban areas. Little is known, however, about how variations in microplastic abundances within watersheds affect fishes. Microplastics were examined in demersal fishes—white sucker (Catostomus commersonii) and common carp (Cyprinus carpio)—across 11 sites in the Thames River, Ontario, Canada. Microplastics were found in 44% of white sucker, ranging from 0 to 14 particles per fish, and 31% of common carp, ranging from 0 to 128 particles per fish. Across both species, the number of microplastics was higher in urban sites than rural sites, and there was a positive relationship between the number of microplastics in the fish and the abundance of microplastics in the sediment. Body mass was also positively related to number of microplastics in fish. Together these results provide insight into environmental and biological factors that may be influencing microplastic ingestion in demersal fishes. [Display omitted] • Demersal river fish ingested fragments, fibres and tire wear particles. • 44% of white sucker and 31% of common carp contained at least one particle. • Microplastic in fish were related to body mass and land use; not species dependent. • Amount of microplastics in sediment may be useful to indicate amounts in fish. [ABSTRACT FROM AUTHOR]

Microplastics are a source of environmental pollution resulting from degradation of plastic products and spillage of resin pellets. We report the amounts of microplastics from various sites of Lake Ontario and evaluate their potential for preservation in the sediment record. A total of 4635 pellets were sampled from the Humber Bay shoreline on three sampling dates. Pellet colours were similar to those from the Humber River bank, suggesting that the river is a pathway for plastics transport into Lake Ontario. Once in the lake, high density microplastics, including mineral-polyethylene and mineral-polypropylene mixtures, sink to the bottom. The minerals may be fillers that were combined with plastics during production, or may have adsorbed to the surfaces of the polymers in the water column or on the lake bottom. Based on sediment depths and accumulation rates, microplastics have accumulated in the offshore region for less than 38 years. Their burial increases the chance of microplastics preservation. Shoreline pellets may not be preserved because they are mingled with organic debris that is reworked during storm events. [ABSTRACT FROM AUTHOR]

Offshore and nearshore sediment samples from Lake Huron, North America, were analysed for microplastics. Normalized abundances ranged from 59 to 335,714 particles per kg of dry weight sediment (p kg−1 dw). Of the four main basins of Lake Huron, the North Channel contained the greatest microplastic abundances, averaging 47,398 p kg−1 dw, followed by Georgian Bay (21,390 p kg−1 dw), the main basin (15,910 p kg−1 dw) and Saginaw Bay (1592 p kg−1 dw). Results indicate that greater lake depths (p = 0.004), associated with finer grained sediment (p = 0.048), are significant zones of deposition. Regression analysis reveals that source-driven factors generally do not account for microplastic abundances and distribution. Instead, process-driven hydrodynamic forces such as waves and surface currents could be driving distribution and deposition into the offshore environment. The findings suggest that these often overlooked processes should be considered when investigating microplastics quantity in bottom sediment of large lakes. • Greater depths of the lake, associated with finer grained sediment, represent significant zones of deposition in Lake Huron. • Hydrodynamic forces could be driving microplastic dispersion and deposition into the offshore environment. • Microplastic distribution is primarily process-driven as opposed to source-driven. [ABSTRACT FROM AUTHOR]

Abstract: The ephemeral nature of most sedimentation processes and the fragmentary character of the sedimentary record are of first-order importance. Despite a basic uniformity of external controls on sedimentation resulting in markedly similar lithologies, facies, facies associations and depositional elements within the rock record across time, there are a number of secular changes, particularly in rates and intensities of processes that resulted in contrasts between preserved Precambrian and Phanerozoic successions. Secular change encompassed (1) variations in mantle heat, rates of plate drift and of continental crustal growth, the gravitational effects of the Moon, and in rates of weathering, erosion, transport, deposition and diagenesis; (2) a decreasing planetary rotation rate over time; (3) no vegetation in the Precambrian, but prolific microbial mats, with the opposite pertaining to the Phanerozoic; (4) the long-term evolution of the hydrosphere–atmosphere–biosphere system. A relatively abrupt and sharp turning point was reached in the Neoarchaean, with spikes in mantle plume flux and tectonothermal activity and possibly concomitant onset of the supercontinent cycle. Substantial and irreversible change occurred subsequently in the Palaeoproterozoic, whereby the dramatic change from reducing to oxidizing volcanic gases ushered in change to an oxic environment, to be followed at ca. 2.4–2.3Ga by the “Great Oxidation Event” (GOE); rise in atmospheric oxygen was accompanied by expansion of oxygenic photosynthesis in the cyanobacteria. A possible global tectono-thermal “slowdown” from ca. 2.45–2.2Ga may have separated a preceding plate regime which interacted with a higher energy mantle from a ca. 2.2–2.0Ga Phanerozoic-style plate tectonic regime; the “slowdown” period also encompassed the first known global-scale glaciation and overlapped with the GOE. While large palaeodeserts emerged from ca. 2.0–1.8Ga, possibly associated with the evolution of the supercontinent cycle, widespread euxinia by ca. 1.85Ga ushered in the “boring billion” year period. A second time of significant and irreversible change, in the Neoproterozoic, saw a second major oxidation event and several low palaeolatitude Cryogenian (740–630Ma) glaciations. With the veracity of the “Snowball Earth” model for Neoproterozoic glaciation being under dispute, genesis of Pre-Ediacaran low-palaeolatitude glaciation remains enigmatic. Ediacaran (635–542Ma) glaciation with a wide palaeolatitudinal range contrasts with the circum-polar nature of Phanerozoic glaciation. The observed change from low latitude to circum-polar glaciation parallels advent and diversification of the Metazoa and the Neoproterozoic oxygenation (ca. 580Ma), and was succeeded by the Ediacaran–Cambrian transition which ushered in biomineralization, with all its implications for the chemical sedimentary record. [Copyright &y& Elsevier]

Abstract: The Slave Craton is composed of five Archaean terranes that accreted during the Neoarchean. The Central Slave superterrane is the only tectonic block containing evidence of four major sedimentary successions, including 1) a quartz arenite-dominated succession deposited on an extensive tide-influenced coastline along a rifted continental margin, 2) a turbidite-dominated succession that developed as submarine fans in a fore-arc or intra-arc basin, 3) a second turbidite succession representing deep water deposition in a back-arc basin, and 4) late conglomerate-dominated successions representing fluvial, alluvial fan and shallow water depositional settings in strike-slip basins. Deposition of the sedimentary rocks took place between ca. 3.1 Ga and 2.6 Ga, indicating a complex tectonic history. An unconformity between the gneissic basement and the overlying quartz arenite succession marks a marine flooding surface consistent with a first order sea level change. A major hiatus lies between the quartz arenite successions and arc-backarc related volcanic deposits with interstratified and conformably overlying turbidite strata. Late conglomerate successions are exposed along north-trending lineaments and overlie all sedimentary and volcanic rock units unconformably. This depositional hiatus represents a fundamental change from compression and uplift to transcurrent motion during the final stages of craton stabilization. Between ca. 2630 and 2580 Ma, the Slave Province experienced considerable pluton emplacement, which disaggregated much of the once-continuous stratigraphy. A Wheeler diagram illustrates the major tectonic events that occurred during formation of the Central Slave superterrane, however, remaining uncertainties concerning the evolution of the entire Slave craton reflect the need for additional detailed field investigations. [Copyright &y& Elsevier]

Abstract: Plastic debris is accumulating on the beaches of Kauai at an alarming rate, averaging 484 pieces/day in one locality. Particles sampled were analyzed to determine the effects of mechanical and chemical processes on the breakdown of polymers in a subtropical setting. Scanning electron microscopy (SEM) indicates that plastic surfaces contain fractures, horizontal notches, flakes, pits, grooves, and vermiculate textures. The mechanically produced textures provide ideal loci for chemical weathering to occur which further weakens the polymer surface leading to embrittlement. Fourier transform infrared spectroscopy (FTIR) results show that some particles have highly oxidized surfaces as indicated by intense peaks in the lower wavenumber region of the spectra. Our textural analyses suggest that polyethylene has the potential to degrade more readily than polypropylene. Further evaluation of plastic degradation in the natural environment may lead to a shift away from the production and use of plastic materials with longer residence times. [Copyright &y& Elsevier]

Plastic debris in Earth’s oceans presents a serious environmental issue because breakdown by chemical weathering and mechanical erosion is minimal at sea. Following deposition on beaches, plastic materials are exposed to UV radiation and physical processes controlled by wind, current, wave and tide action. Plastic particles from Kauai’s beaches were sampled to determine relationships between composition, surface textures, and plastics degradation. SEM images indicated that beach plastics feature both mechanically eroded and chemically weathered surface textures. Granular oxidation textures were concentrated along mechanically weakened fractures and along the margins of the more rounded plastic particles. Particles with oxidation textures also produced the most intense peaks in the lower wavenumber region of FTIR spectra. The textural results suggest that plastic debris is particularly conducive to both chemical and mechanical breakdown in beach environments, which cannot be said for plastics in other natural settings on Earth. [Copyright &y& Elsevier]

Industrial, pre-consumer pellets are a major type of plastics pollution found on shorelines worldwide. This study investigates the distribution and characteristics of plastic pellets accumulated on beaches of the Laurentian Great Lakes of North America and provides a "snapshot" of pellet distribution in a lake system that accounts for 21% of the world's freshwater reserves. We sampled pellets simultaneously from 10m2 quadrats on 66 beaches and characterized the 12,595 pellets collected (average of 19.1 pellets/m2). Forty-two beaches contained pellets and 86% of the pellets were found on three beaches: Rossport (Lake Superior), Baxter (Lake Huron), and Bronte (Lake Ontario). The number of pellets on each beach was compared with factors hypothesized to control their accumulation. In general, positive correlations were found between pellet abundance and watershed population, number of plastic-related industries, and proximity to a river mouth, although for Lake Superior, abundance was related to a train spill that took place over 10 years ago. Beach grain size appears to be related to pellet abundance, with very fine sand, fine sand and medium sand containing the greatest number of pellets. All pellets were visually characterized based on size, color, shape, weathering, and distinguishing traits. The predominant color was white, oblate shapes were most common, and the main distinguishing trait was a dimple. Most pellets showed little evidence of weathering, with the weathered samples mainly from Lakes Erie and Ontario. Lake Ontario pellets were the most varied, with 6/7 shapes, 35/40 colors, and 21/25 distinguishing traits, indicating a wider range of pellet sources compared to the other lakes. Polymer compositions were mainly polyethylene (PE) and polypropylene (PP). Our results will lead to increased recognition of regional pellet pollution in the Great Lakes watershed, thereby motivating change during their production, transport and use. Unlabelled Image • Shorelines of the Great Lakes are littered with industrial plastic pellets. • 42 of 66 beaches contained pellets, for an average of 19.1 pellets/m2. • Abundance increased with number of plastic industries and proximity to river mouths. • Variety was greatest on a beach in a watershed containing 112 plastic industries. • Pellets were most abundant on very fine, fine, and medium sand beaches. [ABSTRACT FROM AUTHOR]