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.     

Assessing and managing freshwater ecosystems vulnerable to environmental change

Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.     

The integrated biomarker response revisited: optimization to avoid misuse

The growing need to evaluate the quality of aquatic ecosystems led to the development of numerous monitoring tools. Among them, the development of biomarker-based procedures, that combine precocity and relevance, is recommended. However, multi-biomarker approaches are often hard to interpret, and produce results that are not easy to integrate in the environmental policies framework. Integrative index have been developed, and one of the most used is the integrated biomarker response (IBR). However, an analysis of available literature demonstrated that the IBR suffers from a frequent misuse and a bias in its calculation. Then, we propose here a new calculation method based on both a more simple formula and a permutation procedure. Together, these improvements should rightly avoid the misuse and bias that were recorded. Additionally, a case study illustrates how the new procedure enabled to perform a reliable classification of site along a pollution gradient based on biomarker responses used in the IBR calculations.     

Fate of nickel in a lime-stabilized biosolid,a calcareous soil and soil–biosolid mixtures

Soil contamination with anthropogenic metals resulting from biosolid application is widespread around the world. To better predict the environmental fate and mobility of contaminants, it is critical to study the capacity of biosolid-amended soils to retain and release metals. In this paper, nickel adsorption onto a calcareous soil, a lime-stabilized biosolid, and soil–biosolid mixtures (30, 75, and 150 t biosolid/ha) was studied in batch experiments. Sorption experiments showed that (1) Ni adsorption was higher onto the biosolid than the calcareous soil, and (2) biosolid acted as an adsorbent in the biosolid–soil mixtures by increasing Ni retention capacity. The sorption tests were complemented with the estimation of Ni adsorption reversibility by successive applications of extraction solutions with water, calcium (100 mg/L), and oxalic acid (equivalent to 100 mg carbon/L). It has been shown that Ni desorption rates in soil and biosolid-amended soils were lower than 30 % whatever the chemical reagent, indicating that Ni was strongly adsorbed on the different systems. This adsorption/desorption hysteresis effect was particularly significant at the highest biosolid concentration (150 t/ha). Finally, an adsorption empirical model was used to estimate the maximum permissible biosolid application rate using French national guideline. It has been shown that desorption effects should be quantitatively considered to estimate relevant biosolid loadings.     

Biomass smoke in Burkina Faso: what is the relationship between particulate matter,carbon monoxide,and kitchen characteristics?

In Burkina Faso where cooking with biomass is very common, little information exists regarding kitchen characteristics and their impact on air pollutant levels. The measurement of air pollutants such as respirable particulate matter (PM₁₀), an important component of biomass smoke that has been linked to adverse health outcomes, can also pose challenges in terms of cost and the type of equipment needed. Carbon monoxide could potentially be a more economical and simpler measure of air pollution. The focus of this study was to first assess the association of kitchen characteristics with measured PM₁₀ and CO levels and second, the relationship of PM₁₀ with CO concentrations, across these different kitchen characteristics in households in Nouna, Burkina Faso. Twenty-four-hour concentrations of PM₁₀ (area) were measured with portable monitors and CO (area and personal) estimated using color dosimeter tubes. Data on kitchen characteristics were collected through surveys. Most households used both wood and charcoal burned in three-stone and charcoal stoves. Mean outdoor kitchen PM₁₀ levels were relatively high (774 μg/m³, 95 % CI 329–1,218 μg/m³), but lower than indoor concentrations (Satterthwaite t value, ?6.14; p?<?0.0001). In multivariable analyses, outdoor kitchens were negatively associated with PM₁₀ (OR?=?0.06, 95 % CI 0.02–0.16, p value <0.0001) and CO (OR?=?0.03, 95 % CI 0.01–0.11, p value <0.0001) concentrations. Strong area PM₁₀ and area CO correlations were found with indoor kitchens (Spearman’s r?=?0.82, p?<?0.0001), indoor stove use (Spearman’s r?=?0.82, p?<?0.0001), and the presence of a smoker in the household (Spearman’s r?=?0.83, p?<?0.0001). Weak correlations between area PM₁₀ and personal CO levels were observed with three-stone (Spearman’s r?=?0.23, p?=?0.008) and improved stoves (Spearman’s r?=?0.34, p?=?0.003). This indicates that the extensive use of biomass fuels and multiple stove types for cooking still produce relatively high levels of exposure, even outdoors, suggesting that both fuel subsidies and stove improvement programs are likely necessary to address this problem. These findings also indicate that area CO color dosimeter tubes could be a useful measure of area PM₁₀ concentrations when levels are influenced by strong emission sources or when used in indoors. The weaker correlation observed between area PM₁₀ and personal CO levels suggests that area exposures are not as useful as proxies for personal exposures, which can vary widely from those recorded by stationary monitors.     

Gemfibrozil modulates cytochrome P450 and peroxisome proliferation-inducible enzymes in the liver of the yellow European eel (Anguilla anguilla)

The human lipid regulator gemfibrozil (GEM) has been shown to induce peroxisome proliferation in rodents leading to hepatocarcinogenesis. Since GEM is found at biological active concentrations in the aquatic environment, the present study investigates the effects of this drug on the yellow European eel (Anguilla anguilla). Eels were injected with different concentrations of GEM (0.1 to 200 μg/g) and sampled 24- and 96-h post-injection. GEM was shown to inhibit CYP1A, CYP3A and CYP2K-like catalytic activities 24-h post-injection, but at 96-h post-injection, only CYP1A was significantly altered in fish injected with the highest GEM dose. On the contrary, GEM had little effect on the phase II enzymes examined (UDP-glucuronyltransferase and glutathione-S-transferase). Peroxisome proliferation inducible enzymes (liver peroxisomal acyl-CoA oxidase and catalase) were very weakly induced. No evidence of a significant effect on the endocrine system of eels was observed in terms of plasmatic steroid levels or testosterone esterification in the liver.     

Bages-Sigean and Canet-St Nazaire lagoons (France): physico-chemical characteristics and contaminant concentrations (Cu,Cd, PCBs and PBDEs) as environmental quality of water and sediment

Environmental characteristics in water and sediments of two contrasted coastal Mediterranean lagoons, Bages-Sigean and Canet-St Nazaire, were measured over a three season survey. The urban pollution (treatment plant discharges) is very important in Canet-St Nazaire lagoon reflecting untreated sewages, while in Bages-Sigean, the northern part appears more impacted due to larger anthropogenic inputs. Dissolved Cd concentrations are on the whole similar in both lagoons, whereas Cu concentrations are by far higher in lagoon Canet-St Nazaire. Cu concentrations appear to be highly dependent on dissolved organic carbon whereas salinity seems to control Cd variations. Concerning the sediments, the confined northern part of lagoon Bages-Sigean shows organic carbon and total nitrogen enrichment whereas lipid concentrations are much higher in the Canet-St Nazaire lagoon. Cu complexation seems to be strongly related to organic matter as evidenced by the two significant positive relationships, on one hand between Cu and organic carbon, and on the other hand, between Cu and lipids. On the contrary, Cd concentrations appear to be mainly controlled by carbonates. PCBs and PBDEs were detected only in sediments and show relatively low concentrations compared to similar lagoon environments. Regarding the sediment quality guidelines, Cd, Cu and PCBs in both lagoons did not exceed any Probable Effect Concentration (PEC).     

Environmental monitoring of alcohol sulfates and alcohol ethoxysulfates in marine sediments

The study describes the environmental monitoring of anionic surfactants―alcohol sulfates (AS) and alcohol ethoxysulfates (AES)—in marine sediments. Concentration values were obtained after pressurised liquid extraction (PLE) and liquid chromatography–tandem mass spectrometry analysis (LC–MS/MS). Samples were collected from a range of wastewater discharge points along the coast of the provinces of Huelva, Málaga, Granada and Almería. Urban, agricultural and industrial wastewaters are discharged at the selected 38 sampling sites. Principal component analysis was carried out in order to evaluate the distribution and behaviour of these compounds in these coastal environments. Evaluation of the data revealed that the behaviour and sources of AS and AES in marine sediments are different, and that the distribution of AES depends on the length of the alkyl chain, while the number of ethoxylated units is not relevant. Additionally, the 38 sampling sites can be grouped into only two types of outfalls according to their AS distribution. The concentration of compounds in sediment samples ranged from 7.52 to 13.50 mg kg^?1 for AS, from 3.04 to 10.68 mg kg^?1 for AES–C₁₂E_x and from 3.83 to 11.56 mg kg^?1 for AES–C₁₄E_x.     

Effect of ibuprofen exposure on blood,gill, liver,and brain on common carp (Cyprinus carpio) using oxidative stress biomarkers

Although trace concentrations of ibuprofen (IBP) have been detected in diverse water bodies, there is currently insufficient information on the potentially deleterious effects of this xenobiotic. The present study aimed to determine whether IBP induces oxidative stress in brain, liver, gill, and blood of the common carp Cyprinus carpio. To this end, the median lethal concentration at 96 h (96-h LC₅₀) was determined and the lowest observed adverse effect level was established. Carp were exposed to the latter concentration (17.6 mg L^?1) for 12, 24, 48, 72, and 96 h, and the following biomarkers were evaluated: lipid peroxidation (LPX) and activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. Results indicated that LPX and antioxidant enzymes’ activity increased significantly (p?<?0.05) with respect to the control group in liver, gill, and blood, while no significant differences occurred in brain. In conclusion, IBP induced oxidative stress on C. carpio, the liver being the organ most affected by this damage.     

Distribution and ecological risk of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in surface sediments from the Bizerte lagoon,Tunisia

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in 18 surface sediment samples collected from Bizerte lagoon, Tunisia. The total concentrations of ten PCBs (∑PCBs) and of four OCPs (∑OCPs) in the sediments from this area ranged from 0.8 to 14.6 ng g^?1 dw (average value, 3.9 ng g^?1 dw) and from 1.1 to 14.0 ng g^?1 dw (average value, 3.3 ng g^?1 dw), respectively. Among the OCPs, the range of concentrations of dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorobenzene (HCB) were 0.3–11.5 ng g^?1 dw (1.9 ng g^?1 dw) and 0.6–2.5 ng g^?1 dw (1.4 ng g^?1 dw), respectively. Compositional analyses of the POPs indicated that PCB 153, 138 and 180 were the predominant congeners accounting for 60 % of the total PCBs. In addition, p,p′-DDT was found to be the dominant DDTs, demonstrating recent inputs in the environment. Compared with some other regions of the world, the Bizerte lagoon exhibited low levels of PCBs and moderate levels of HCB and DDTs. The high ratios ΣPCBs/ΣDDTs indicated predominant industrial versus agricultural activities in this area. According to the established guidelines for sediment quality, the risk of adverse biological effects from such levels of OCPs and PCBs, as recorded at most of the study sites, was insignificant. However, the higher concentrations in stations S1 and S3 could cause biological damage.