Soil carbon sequestration in a changing global environment

Throughout its long history the Earth has undergone warm periods with high atmospheric concentrations of greenhouse gases (GHG), and has responded with different buffering mechanisms whereby atmospheric C has been transferred to other geochemical compartments. Strategies for the mitigation and adaptation to the current climatic forcing may thus be generated by the acceleration of such natural mechanisms, especially those involved in short cycles, mainly in the biosphere and the pedosphere. Although these contain smaller C stocks than other compartments (< 0.01% of the total C), they circulate large amounts of C from the atmosphere through photosynthesis and mineral weathering (e.g., 120 Pg C are circulated through terrestrial ecosystems and total C in the atmospheric compartment is 805 Pg C). Increased C sequestration can thus be achieved in terrestrial ecosystems, by: (1) favouring growth of biomass; (2) promoting and facilitating carbonation processes; (3) reducing erosion and favouring pedogenesis; (4) developing organic matter-rich horizons; (5) recovering degraded or contaminated soils, and/or (6) managing waste by use of systems that minimize emissions of GHG. Within the latter option, the following actions are considered here in more detail: 1) production of Technosols, and 2) production of biochar. All of the above options should form part of a strategy for the mitigation and adaptation to global climate change. In this review, we analyze those focused on promoting soil conservation, soil restoration and soil formation.     

Design and Application of Nucleic Acid Standards for Quantitative Detection of Enteric Viruses by Real-Time PCR

Synthetic multiple-target RNA and DNA oligonucleotides were constructed for use as quantification standards for nucleic acid amplification assays for human norovirus genogroup I and II, hepatitis E virus, murine norovirus, human adenovirus, porcine adenovirus and bovine polyomavirus. This approach overcomes the problems related to the difficulty of obtaining practical quantities of viral RNA and DNA from these viruses. The quantification capacity of assays using the standards was excellent in each case (R ² > 0.998 and PCR efficiency > 0.89). The copy numbers of the standards were equivalent to the genome equivalents of representative viruses (murine norovirus and human adenovirus), ensuring an accurate determination of virus presence. The availability of these standards should facilitate the implementation of nucleic acid amplification-based methods for quantitative virus detection.     

Reduction in ecological cost through biofuel production from cooking oils: An ecological solution for the city of Campinas, Brazil

The aim of the present study was to produce biodiesel from mixtures of cooking oil and provide a possible environmental solution for the region of Campinas (state of São Paulo, Brazil) based on the theory of environmental cost accounting (ECA). Cooking oil collected from homes in Campinas was mixed with ethanol at a ratio of 7:1 and transesterified at 60 °C for one hour for the obtainment of biodiesel using NaOH as a catalyst. The results of the physicochemical analyses demonstrated that the biodiesel possessed characteristics close to those required by Brazilian standards. A recent survey carried out in the city of Campinas revealed that residents are not concerned with the increased of environmental impact and ecological costs in the region caused by the disposal of used cooking oil, which is discarded in sewers and soil. Urgent action is recommended, beginning with raising awareness among the population and the implementation of a policy to determine the storage, periodic collection and use of cooking oil for the production of biodiesel. This fuel could be used for buses, trucks and machines or sold to fuel distributors, offering a savings of US$ 0.8 to 4.5 millions. Campinas could then gain environmental credits and become a sustainable city. Moreover, used cooking oil constitutes low-cost biodiesel with no consumption of raw materials and will reduce worldwide criticism directed at Brazil regarding the use of oleaginous plants for biodiesel production.     

Biomarkers of oxidative status associated with metal pollution in the blood of the white stork (Ciconia ciconia) in Spain

The aim of this study was to determine the impact of specific environmental contaminants on the activities of antioxidant enzymes in terrestrial, free-living birds. To investigate this, several biomarkers and the levels of lead, mercury, and arsenic were determined in blood of white stork (Ciconia ciconia) nestlings from two different colonies located in the west of Spain that were exposed to different environmental conditions and human activities. Different biomarker and contaminant patterns were observed between the two colonies, suggesting different levels of environmental contamination. In comparison to nestlings from a natural reference area, the levels of the three hazardous elements Pb, As, and Hg were significantly higher in the colony nearby a landfill. Analysis of antioxidant biomarkers revealed significantly higher levels of glutathione and glutathione S-transferase activity in birds from the colony close to the landfill site than were found in those from the “control” area. In contrast, the levels of malondialdehyde did not significantly differ between the two sampling sites. In addition, a positive correlation between glutathione and both Hg and As has been observed. Taken together, exposure to the three hazardous elements is reflected by enhanced activity of glutathione S-transferases, and elevated levels of glutathione and malondialdehyde. White storks can therefore be considered as a suitable model species for environmental monitoring programs.     

Effects of different management strategies on long-term trends of Australian threatened and near-threatened mammals

Monitoring is critical to assess management effectiveness, but broadscale systematic assessments of monitoring to evaluate and improve recovery efforts are lacking. We compiled 1808 time series from 71 threatened and near-threatened terrestrial and volant mammal species and subspecies in Australia (48% of all threatened mammal taxa) to compare relative trends of populations subject to different management strategies. We adapted the Living Planet Index to develop the Threatened Species Index for Australian Mammals and track aggregate trends for all sampled threatened mammal populations and for small (<35 g), medium (35–5500 g), and large mammals (>5500 g) from 2000 to 2017. Unmanaged populations (42 taxa) declined by 63% on average; unmanaged small mammals exhibited the greatest declines (96%). Populations of 17 taxa in havens (islands and fenced areas that excluded or eliminated introduced red foxes [Vulpes vulpes] and domestic cats [Felis catus]) increased by 680%. Outside havens, populations undergoing sustained predator baiting initially declined by 75% but subsequently increased to 47% of their abundance in 2000. At sites where predators were not excluded or baited but other actions (e.g., fire management, introduced herbivore control) occurred, populations of small and medium mammals declined faster, but large mammals declined more slowly, than unmanaged populations. Only 13% of taxa had data for both unmanaged and managed populations; index comparisons for this subset showed that taxa with populations increasing inside havens declined outside havens but taxa with populations subject to predator baiting outside havens declined more slowly than populations with no management and then increased, whereas unmanaged populations continued to decline. More comprehensive and improved monitoring (particularly encompassing poorly represented management actions and taxonomic groups like bats and small mammals) is required to understand whether and where management has worked. Improved implementation of management for threats other than predation is critical to recover Australia's threatened mammals.     

Relationship between plant biodiversity and heavy metal bioavailability in grasslands overlying an abandoned mine

Abandoned metal mines in the Sierra de Guadarrama, Madrid, Spain, are often located in areas of high ecological value. This is true of an abandoned barium mine situated in the heart of a bird sanctuary. Today the area sustains grasslands, interspersed with oakwood formations of Quercus ilex and heywood scrub (Retama sphaerocarpa L.), used by cattle, sheep and wild animals. Our study was designed to establish a relationship between the plant biodiversity of these grasslands and the bioavailability of heavy metals in the topsoil layer of this abandoned mine. We conducted soil chemical analyses and performed a greenhouse evaluation of the effects of different soil heavy metal concentrations on biodiversity. The greenhouse bioassays were run for 6 months using soil samples obtained from the mine polluted with heavy metals (Cu, Zn, Pb and Cd) and from a control pasture. Soil heavy metal and Na concentrations, along with the pH, had intense negative effects on plant biodiversity, as determined through changes in the Shannon index and species richness. Numbers of grasses, legumes, and composites were reduced, whilst other species (including ruderals) were affected to a lesser extent. Zinc had the greatest effect on biodiversity, followed by Cd and Cu. When we compared the sensitivity of the biodiversity indicators to the different metal content variables, pseudototal metal concentrations determined by X-ray fluorescence (XRF) were the most sensitive, followed by available and soluble metal contents. Worse correlations between biodiversity variables and metal variables were shown by pseudototal contents obtained by plasma emission spectroscopy (ICP-OES). Our results highlight the importance of using as many different indicators as possible to reliably assess the response shown by plants to heavy metal soil pollution.     

Performance of the National Water Model in Iowa Using Independent Observations

This paper explores the performance of the analysis‐and‐assimilation configuration of the National Water Model (NWM) v1.0 in Iowa. The NWM assimilates streamflow observations from the United States Geological Survey (USGS), which increases the performance but also limits the available data for model evaluation. In this study, Iowa Flood Center Bridge Sensors (IFCBS) data provided an independent nonassimilated dataset for evaluation analyses. The authors compared NWM outputs for the period between May 2016 and April 2017, with two datasets: USGS streamflow and velocity observations; Stage and streamflow data from IFCBS. The distribution of Spearman rank correlation (r_s), Nash–Sutcliffe efficiency (E), and Kling–Gupta efficiency (KGE) provided quantification of model performance. We found the performance was linked with the spatial scale of the basins. Analysis at USGS gauges showed the strongest performance in large (>10,000 km²) basins (r_s = 0.9, E = 0.9, KGE = 0.8), with some decrease at small (<1,000 km²) basins (r_s = 0.6, E = ?0.25, KGE = ?0.2). Analysis with independent IFCBS observations was used to report performance at large basins (r_s = 0.6, KGE = 0.1) and small basins (r_s = 0.2, KGE = ?0.4). Data assimilation improves simulations at downstream basins. We found differences in the characterization of the model and observed data flow velocity distributions. The authors recommend checking the connection of USGS gauges and NHDPlus reaches for selected locations where performance is weak.     

Toxicity testing of pesticides in zebrafish—a systematic review on chemicals and associated toxicological endpoints

The use of zebrafish (Danio rerio) has arisen as a promising biological platform for toxicity testing of pesticides such as herbicides, insecticides, and fungicides. Therefore, it is relevant to assess the use of zebrafish in models of exposure to investigate the diversity of pesticide-associated toxicity endpoints which have been reported. Thus, this review aimed to assess the recent literature on the use of zebrafish in pesticide toxicity studies to capture data on the types of pesticide used, classes of pesticides, and zebrafish life stages associated with toxicity endpoints and phenotypic observations. A total of 352 articles published between September 2012 and May 2019 were curated. The results show an increased trend in the use of zebrafish for testing the toxicity of pesticides, with a great diversity of pesticides (203) and chemical classes (58) with different applications (41) being used. Furthermore, experimental outcomes could be clustered in 13 toxicity endpoints, mainly developmental toxicity, oxidative stress, and neurotoxicity. Organophosphorus, pyrethroid, azole, and triazine were the most studied classes of pesticides and associated with various toxicity endpoints. Studies frequently opted for early life stages (embryos and larvae). Although there is an evident lack of standardization of nomenclatures and phenotypic alterations, the information gathered here highlights associations between (classes of) pesticides and endpoints, which can be used to relate mechanisms of action specific to certain classes of chemicals.     

Improving the Rheological and Mechanical Properties of Recycled PET Modified by Macromolecular Chain Extenders Synthesized by Controlled Radical Polymerization

In this work, a series of reactive copolymers of glycidyl methacrylate (G), styrene (S) and acrylonitrile (AN), were synthesized through reversible addition-fragmentation chain transfer polymerization and evaluated as macromolecular chain extenders in reactive extrusion of recycled poly(ethylene terephthalate) (rPET). The results obtained indicate that the addition of the reactive copolymers as chain extenders modifies the chain conformation in rPET causing low crystallization rate and low crystallinity. The physical and rheological properties (melt flow and intrinsic viscosity) of chain-extended rPET improved, rendering better processability. rPET modified with polymeric chain extenders shows improved rheological properties (complex viscosity, storage and loss modulus) and also displays higher elongation at break and impact properties as the GMA content in the chain extenders increase.