Recyclable textiles functionalized with reduced graphene Oxide@ZnO for removal of oil spills and dye pollutants

A novel recyclable and flexible membrane was prepared for the removal of oil spills and organic dye pollutants, by functionalizing polyester textiles with reduced graphene oxide@ZnO nanocomposites using a layer-by-layer technique. The membrane showed efficient water/oil separation, and the amount of oil adsorbed by the membrane could be up to 23 times its own weight. The adsorption capacity was largely retained during many adsorption recycling cycles. The membrane also displayed highly efficient removal of a dye pollutant from water under simulated sunlight. The membrane maintained a near-original removal efficiency after five cycles of dye removal. This new type of membrane may find practical applications in the large-scale separation of organic pollutants from water, particularly in the field of oil spills clean-up and dye removal from industrial effluent.

Climate-driven impacts of prey abundance on the population structure of a tropical aquatic predator

In the present study we explore how annual variation in climate (late wet-season rainfall) affects population demography in a gape-limited obligate piscivorous predator, the Arafura filesnake Acrochordus arafurae in the Australian tropics. These aquatic snakes display extreme sexual dimorphism, with body sizes and relative head sizes of females much larger than those of males. Two consecutive years with low rainfall during the late wet season reduced the abundance of small but not large sized fish. Although snake residual body mass (RBM, calculated from a general linear regression of ln-transformed mass to ln-SVL) decreased after the first year with low prey availability, it was not until the second year that reduced prey abundance caused a dramatic decline in filesnake survival, and hence in population numbers. Thus, our results suggest that most snakes survived the first year of reduced prey abundance, but a successive year with low prey availability proved fatal for many animals. However, the effects of prey scarcity on RBM and survival fell disproportionately on some size classes of snakes. Medium-sized animals (large males and intermediate-sized females) were affected more dramatically than were small or large snakes. We attribute the higher survival of small snakes to their lower energy needs compared to medium-sized individuals, and the higher survival of large snakes to the continued abundance of large prey (mainly large catfish). Two successive years with low abundance of smaller sized prey thus massively modified the size-structure of the filesnake population, virtually eliminating large males and intermediate-sized females. Our field data provide a clear demonstration of the ways in which stochastic variation in climatic conditions can have dramatic effects on predator population demography, mediated via effects on prey availability.

Pop, heavy metal and the blues: secondary analysis of persistent organic pollutants (POP), heavy metals and depressive symptoms in the NHANES National Epidemiological Survey

Persistent environmental pollutants, including heavy metals and persistent organic pollutants (POPs), have a ubiquitous presence. Many of these pollutants affect neurobiological processes, either accidentally or by design. The aim of this study was to explore the associations between assayed measures of POPs and heavy metals and depressive symptoms. We hypothesised that higher levels of pollutants and metals would be associated with depressive symptoms.

Edge patterns in aquatic invertebrates explained by predictive models

Predictive frameworks for understanding and describing how animals respond to habitat fragmentation, particularly across edges, have been largely restricted to terrestrial systems. Abundances of zooplankton and meiofauna were measured across seagrasssand edges and the patterns compared with predictive models of edge effects. Artificial seagrass patches were placed on bare sand, and zooplankton and meiofauna were sampled with tube traps at five positions (from patch edges: 12, 60 and 130 cm into seagrass; and 12 and 60 cm onto sand). Position effects consisted of the following three general patterns: (1) increases in abundance around the seagrasssand edge (total abundance and cumaceans); (2) declining abundance from seagrass onto sand (calanoid copepods, harpacticoid copepods and amphipods); and (3) increasing abundance from seagrass onto sand (crustacean nauplii and bivalve larvae). The first two patterns are consistent with resource-distribution models, either as higher resources at the confluence of adjacent habitats or supplementation of resources from high-quality to low-quality habitat. The third pattern is consistent with reductions in zooplankton abundance as a consequence of predation or attenuation of currents by seagrass. The results show that predictive models of edge effects can apply to aquatic animals and that edges are important in structuring zooplankton and meiofauna assemblages in seagrass. © 2010 CSIRO.

Aquatic toxicity of manufactured nanomaterials: challenges and recommendations for future toxicity testing

 Aquatic nanotoxicologists and ecotoxicologists have begun to identify the unique properties of the nanomaterials (NMs) that potentially affect the health of wildlife. In this review the scientific aims are to discuss the main challenges nanotoxicologists currently face in aquatic toxicity testing, including the transformations of NMs in aquatic test media (dissolution, aggregation and small molecule interactions), and modes of NM interference (optical interference, adsorption to assay components and generation of reactive oxygen species) on common toxicity assays. Three of the major OECD (Organisation for Economic Co-operation and Development) priority materials, titanium dioxide (TiO2), zinc oxide (ZnO) and silver (Ag) NMs, studied recently by the Natural Sciences and Engineering Research Council of Canada (NSERC), National Research Council of Canada (NRC) and the Business Development Bank of Canada (BDC) Nanotechnology Initiative (NNBNI), a Canadian consortium, have been identified to cause both bulk effect, dissolution-based (i.e. free metal), or NM-specific toxicity in aquatic organisms. TiO2 NMs are most toxic to algae, with toxicity being NM size-dependent and principally associated with binding of the materials to the organism. Conversely, dissolution of Zn and Ag NMs and the subsequent release of their ionic metal counterparts appear to represent the primary mode of toxicity to aquatic organisms for these NMs. In recent years, our understanding of the toxicological properties of these specific OECD relevant materials has increased significantly. Specifically, researchers have begun to alter their experimental design to identify the different behaviour of these materials as colloids and, by introducing appropriate controls and NM characterisation, aquatic nanotoxicologists are now beginning to possess a clearer understanding of the chemical and physical properties of these materials in solution, and how these materials may interact with organisms. Arming nanotoxicologists with this understanding, combined with knowledge of the physics, chemistry and biology of these materials is essential for maintaining the accuracy of all future toxicological assessments.

An Antarctic research station as a source of brominated and perfluorinated persistent organic pollutants to the local environment

This study investigated the role of a permanently manned Australian Antarctic research station (Casey Station) as a source of contemporary persistent organic pollutants (POPs) to the local environment. Polybrominated diphenyl ethers (PBDEs) and poly- and perfluoroalkylated substances (PFASs) were found in indoor dust and treated wastewater effluent of the station. PBDE (e.g., BDE-209 26-820 ng g(-1) dry weight (dw)) and PFAS levels (e.g., PFOS 3.8-2400 ng g(-1) (dw)) in dust were consistent with those previously reported in homes and offices from Australia, reflecting consumer products and materials of the host nation. The levels of PBDEs and PFASs in wastewater (e.g., BDE-209 71-400 ng L(-1)) were in the upper range of concentrations reported for secondary treatment plants in other parts of the world. The chemical profiles of some PFAS samples were, however, different from domestic profiles. Dispersal of chemicals into the immediate marine and terrestrial environments was investigated by analysis of abiotic and biotic matrices. Analytes showed decreasing concentrations with increasing distance from the station. This study provides the first evidence of PFAS input to Polar regions via local research stations and demonstrates the introduction of POPs recently listed under the Stockholm Convention into the Antarctic environment through local human activities.