Comparison of arsenic resistance in Mediterranean woody shrubs used in restoration activities

Myrtus communis, Arbutus unedo and Retama sphaerocarpa are Mediterranean shrubs widely used in revegetation of semiarid degraded soils. The aim of this work is to study the resistance of these plants to arsenic under controlled conditions, in order to evaluate their potential use in revegetation and/or phytoremediation of As-polluted soils. R. sphaerocarpa showed higher resistance to As than M. communis or A. unedo according to its higher EC50, P status and P/As molar ratio in both, roots and shoots, and the lower increases in lipid peroxidation and decrease of chlorophyll levels in response to arsenic, while the highest arsenate sensitivity was obtained for A. unedo. Arsenic was mainly retained in roots, and, although M. communis accumulated higher arsenic amounts than the other two species, R. sphaerocarpa showed the highest root to shoot transfer. Most of the studied parameters (chlorophylls, MDA and total thiols) showed significant correlation with arsenic concentration in roots and leaves of plants, so they can be useful indexes in the diagnosis of arsenic toxicity in these species. According to our results, both M. communis and R. sphaerocarpa could be used in the revegetation of moderately arsenic contaminated sites.     

Chitosan/Hydrophilic Plasticizer-Based Films: Preparation,Physicochemical and Antimicrobial Properties

The addition of plasticizers to biopolymer films is a good method for improving their physicochemical properties. The aim of this study was to evaluate the effect of chitosan (CHI) blended with two hydrophilic plasticizers glycerol (GLY) and sorbitol (SOR), at two concentrations (20 and 40 wt%) on their mechanical, thermal, barrier, structural, morphological and antimicrobial properties. The chitosan was prepared through the alkaline deacetylation of chitin obtained from fermented lactic from shrimp heads. The obtained chitosan had a degree of deacetylation (DA) of 84 ± 2.7 and a molecular weight of 136 kDa, which indicated that a good film had formed. The films composed of CHI and GLY (20 wt%) exhibited the best mechanical properties compared to the neat chitosan film. The percentage of elongation at break increase to over 700 % in the films that contained 40 % GLY, and these films also exhibited the highest values for the water vapor transmission rate (WVTR) of 79.6 ± 1.9 g m² h^?1 and a yellow color (b _o  = 17.9 ± 2.0) compared to the neat chitosan films (b _o  = 8.8 ± 0.8). For the structural properties, the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analyses revealed an interaction in the acetamide group and changes in the crystallinity of plasticized films. The scanning electron micrographs revealed that all formulations of the chitosan films were smooth, and that they did not contain aggregations, pores or microphase separation. The thermal analysis using differential scanning calorimetry (DSC) revealed a glass transition temperature (Tg) of 130 °C for neat chitosan film, but the addition of SOR or GLY elicited a decrease in the temperature of the peak (120 °C). In addition, the antimicrobial activity of the chitosan films was evaluated against Listeria monocytogenes, and reached a reduction of 2 log after 24 h. The plasticizer concentration of 20 % GLY is sufficient for obtaining flexible chitosan films with good mechanical properties, and it could serve as an alternative as a packaging material to reduce environmental problems associated with synthetic packaging films.     

Substituting missing data in compositional analysis

Multivariate analysis of environmental data sets requires the absence of missing values or their substitution by small values. However, if the data is transformed logarithmically prior to the analysis, this solution cannot be applied because the logarithm of a small value might become an outlier. Several methods for substituting the missing values can be found in the literature although none of them guarantees that no distortion of the structure of the data set is produced. We propose a method for the assessment of these distortions which can be used for deciding whether to retain or not the samples or variables containing missing values and for the investigation of the performance of different substitution techniques. The method analyzes the structure of the distances among samples using Mantel tests. We present an application of the method to PCDD/F data measured in samples of terrestrial moss as part of a biomonitoring study.     

Microplastic distribution in surface sediments along the Spanish Mediterranean continental shelf

Environmental Science and Pollution Research - Microplastics (MPs) are widely recognised as a contaminant of emerging concern in the marine environment. This work provides original data of the...     

The progress of interdisciplinarity in invasion science

Interdisciplinarity is needed to gain knowledge of the ecology of invasive species and invaded ecosystems, and of the human dimensions of biological invasions. We combine a quantitative literature review with a qualitative historical narrative to document the progress of interdisciplinarity in invasion science since 1950. Our review shows that 92.4% of interdisciplinary publications (out of 9192) focus on ecological questions, 4.4% on social ones, and 3.2% on social–ecological ones. The emergence of invasion science out of ecology might explain why interdisciplinarity has remained mostly within the natural sciences. Nevertheless, invasion science is attracting social–ecological collaborations to understand ecological challenges, and to develop novel approaches to address new ideas, concepts, and invasion-related questions between scholars and stakeholders. We discuss ways to reframe invasion science as a field centred on interlinked social–ecological dynamics to bring science, governance and society together in a common effort to deal with invasions.     

Innovative aspects of environmental chemistry and technology regarding air,water, and soil pollution

Environmental Science and Pollution Research -     

Effect of sewer headspace air-flow on hydrogen sulfide removal by corroding concrete surfaces

Hydrogen sulfide adsorption and oxidation by corroding concrete surfaces at different air-flows were quantified using a pilot-scale sewer reactor. The setup was installed in an underground sewer research station with direct access to wastewater. Hydrogen sulfide gas was injected into the headspace of the sewer reactor once per hour in peak concentrations of approximately 500 ppmv. The investigated range of sewer air-flows was representative for natural ventilated sewer systems, and covered both laminar and turbulent conditions. The experiments demonstrated a significant effect of sewer air-flow on the kinetics of hydrogen sulfide removal from the sewer headspace. From the lowest to the highest air-flow investigated, the rate of adsorption and oxidation increased more than threefold. At all air-flows, the reaction kinetics followed a simple n-th order rate equation with a reaction order of 0.8. The effect of air-flow on hydrogen sulfide adsorption and oxidation kinetics was quantified by a simple empirical equation.     

Effect of the veterinary ionophore monensin on the structure and activity of a tropical soil bacterial community

Abstract

Monensin (MON) is a coccidiostat used as a growth promoter that can reach the environment through fertilization with manure from farm animals. To verify whether field-relevant concentrations of this drug negatively influence the structure and activity of tropical soil bacteria, plate counts, CO₂ efflux measurements, phospholipid fatty acids (PLFA) and community-level physiological profiling (CLPP) profiles were obtained for soil microcosms exposed to 1 or 10?mg kg^?1 of MON across 11?days. Although 53% (1?mg kg^?1) to 40% (10?mg kg^?1) of the MON concentrations added to the microcosms dissipated within 5?days, a subtle concentration-dependent decrease in the number of culturable bacteria (<1 log CFU g^?1), reduced (?20 to ?30%) or exacerbated (+25%) soil CO₂ effluxes, a marked shift of non-bacterial fatty acids, and altered respiration of amines (1.22-fold decrease) and polymers (1.70-fold increase) were noted in some of the treatments. These results suggest that MON quickly killed some microorganisms and that the surviving populations were selected and metabolically stimulated. Consequently, MON should be monitored in agronomic and environmental systems as part of One Health efforts.