Preparation and Characterization of Clay Nanocomposites of Plasticized Starch and Polypropylene Polymer Blends

Plasticized starch (PLS) is a renewable, degradable, and inexpensive polymer, but it suffers from poor mechanical properties. The mechanical properties can be improved by blending PLS with polyolefins, nonetheless, at high PLS content, the mechanical properties remain poor. Here we show that addition of clay can greatly improve the mechanical properties of PLS/polypropylene blends at high starch content. Unmodified and organically modified montmorillonite clays, MMT and Cloisite 30B respectively, were added to blends of glycerol-plasticized starch and polypropylene, compatibilized using maleated polypropylene. TEM indicates that MMT is well dispersed in the PLS phase of the blends, while Cloisite 30B is located both within the PLS phase as well as at the interface between PLS and PP. At high PLS content, the addition of clay increased the tensile strength and tensile modulus by an order of magnitude, while reducing the ultimate elongation only slightly. Such improvements are attributable to both the addition of clay as a reinforcing component, as well as to the change in the two phase morphology due to addition of clay.     

Forecasting model to assess the potential of secondary lead production from lead acid battery scrap

Environmental Science and Pollution Research - Lead acid battery (LAB) scrap management is an important issue both environmentally and economically. The recovery of lead from battery scrap leads to...     

Aerosol formation yields from the reaction of catechol with ozone

The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers. Aerosol production was monitored using a scanning mobility particle sizer and loss of the precursor was determined by gas chromatography and infrared spectroscopy, whilst ozone concentrations were measured using a UV photometric analyzer. The overall organic aerosol yield (Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses (M_o) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm^?3. Analysis of the data clearly shows that Y is a strong function of M_o and that secondary organic aerosol formation can be expressed by a one-product gas–particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The results of this work are compared to similar studies reported in the literature.     

Physicochemical fingerprinting of thermal waters of Beira Interior region of Portugal

Mineral natural waters and spas have been used for therapeutic purposes for centuries, with Portugal being a very rich country in thermal waters and spas that are mainly distributed by northern and central regions where Beira Interior region is located. The use of thermal waters for therapeutic purposes has always been aroused a continuous interest, being dependent on physicochemical fingerprinting of this type of waters the indication for a treatment in a specific pathological condition. In the present work, besides a literature review about the physicochemical composition of the thermal waters of the Beira Interior region and its therapeutic indications, it was carried out an exhaustive multivariate analysis—principal component analysis and cluster analysis—to assess the correlation between different physicochemical parameters and the therapeutic indications claims described for these spas and thermal waters. These statistical methods used for data analysis enables classification of thermal waters compositions into different groups, regarding to the different variable selected, making possible an interpretation of variables affecting water compositions. Actually, Monfortinho and Longroiva are clearly quite different of the others, and Cró and Fonte Santa de Almeida appear together in all analysis, suggesting a strong resemblance between these waters. Thereafter, the results obtained allow us to demonstrate the role of major components of the studied thermal waters on a particular therapeutic purpose/indication and hence based on compositional and physicochemical properties partially explain their therapeutic qualities and beneficial effects on human health. This classification agreed with the results obtained for the therapeutic indications approved by the Portuguese National Health Authority and proved to be a valuable tool for the regional typology of mineral medicinal waters, constituting an important guide of the therapeutic armamentarium for well and specific-oriented pathological disturbs.     

Anti-oviposition activities of used sock media against a dengue vector: prospects of eco-friendly control and solutions to pollution

Yearly, huge amounts of sock refuse are discarded into the environment. Socks contain many molecules, and worn ones, which are rich in smell-causing bacteria, have a strong influence on animals’ behaviors. But the impacts of sock odor on the oviposition behavior of dengue vectors are unknown. We assessed whether Aedes albopictus changes its oviposition activity in response to the presence of used socks extract (USEx) in potential breeding grounds, using choice and no-choice bioassays (NCB). When furnished even chances to oviposit in two sites holding USEx and two others containing water (control), Ae. albopictus deposited significantly less eggs in USEx than in water sites. A similar pattern of oviposition preference was also observed when there were more oviposition options in water. When there were greater oviposition opportunities in USEx sites, Ae. albopictus oviposited preferentially in water. Females laid significantly more eggs during the NCB involving water than USEx. Also, significantly more mature eggs were retained by females in the NCB with USEx than in that with water. These observations strongly suggest the presence of molecules with either repellent or deterrent activities against Ae. albopictus females and provide an impetus to advocate the integration of used socks in dengue control programs. Such applications could be a realistic end-of-life recourse to reroute this waste from landfills.

     

Arsenic in marine sediments from French Mediterranean ports: Geochemical partitioning,bioavailability and ecotoxicology

This work investigates arsenic mobility, bioavailability and toxicity in marine port sediments using chemical sequential extraction and laboratory toxicity tests. Sediment samples were collected from two different Mediterranean ports, one highly polluted with arsenic and other inorganic and organic pollutants (Estaque port (EST)), and the other one, less polluted, with a low arsenic content (Saint Mandrier port (SM)). Arsenic distribution in the solid phase was studied using a sequential extraction procedure specifically developed for appraising arsenic mobility in sediments. Toxicity assessment was performed on sediment elutriates, solid phases and aqueous arsenic species as single substance using the embryo-toxicity test on oyster larvae (Crassostrea gigas) and the Microtox test with Vibrio fischeri. Toxicity results showed that all sediment samples presented acute and sub-chronic toxic effects on oyster larvae and bacteria, respectively. The Microtox solid phase test allow to discriminate As-contaminated samples from the less contaminated ones, suggesting that toxicity of whole sediment samples is related to arsenic content. Toxicity of dissolved arsenic species as single substance showed that Vibrio fischeri and oyster larvae are most sensitive to As(V) than As(III). The distribution coefficient (Kd) of arsenic in sediment samples was estimated using results obtained in chemical sequential extractions. The Kd value is greater in SM (450 L kg^?1) than in EST (55 L kg^?1), indicating that arsenic availability is higher for the most toxic sediment sample (Estaque port). This study demonstrates that arsenic speciation play an important role on arsenic mobility and its bioavailability in marine port sediments.     

Effect of phenobarbital and polychlorinated biphenyls on the toxicity and disposition of 1,2,4,5‐tetrachlorobenzene in the rat

Soil avoidance by earthworms has been generally considered a relevant and sensitive endpoint for assessing soil contamination by xenobiotics. However, when pesticide ecotoxicological assessment is concerned, the sensitivity of the recently standardized avoidance assay has been questioned. We hypothesized that this controversy may be due to the specific pesticide mode of action of the chemicals used rather than reveal inconsistencies in the test feasibility, i.e. provided that no pesticides interfering with neuronal pathways are tested, this bioassay should keep expected high levels of sensitivity. In this study, the avoidance behaviour of the earthworm Eisenia andrei under exposure to the carbamate insecticide methomyl [S-methyl N-(methylcarbamoyloxy)thioacetimidate] was linked to the corresponding acetylcholinesterase (AChE) inhibition. Significant AChE inhibition occurred at lower concentrations (from 0.86 mg Kg^?1 onwards) than significant avoidance of spiked soil (from 5.62 mg Kg^?1 onwards). This indicates that assessments regarding pesticides that have neurotoxic activity may be biased if behavioral endpoints are selected. Despite theoretical hypothesis that have been raised, this should be the first study providing preliminary experimental evidence on such a link between avoidance behavior and neuronal impairment levels in earthworms. Further studies are ongoing that should refine conclusions of this study.     

Socio-Economic Stakes and Perceptions of Wetland Management in an Arid Region: A Case Study from Chott Merouane, Algeria

The objective of our study was to identify how actors from the main socio-economic sectors perceive their interactions and impacts on a sensitive wetland in an arid climate, specifically the salt pans of Chott Merouane in Algeria. The results revealed that there are three main economic stakes including agriculture, livestock production and salt mining, each activity providing a great benefit for local and national populations. The local population perceived that the current activities are conducted in such a way that they created conflict between socio-economic sectors and caused a threat for long term sustainability of the wetlands. The results highlighted the need to initiate an integrated management approach between the different sectors and to develop a shared vision for the territory.     

New methodological improvements in the Microtox® solid phase assay

The classic Microtox® solid phase assay (MSPA) based on the inhibition of light production of the marine bacteria recently renamed Aliivibrio fischeri suffers from various bias and interferences, mainly due to physico-chemical characteristics of the tested solid phase. To precisely assess ecotoxicity of sediments, we have developed an alternative method, named Microtox® leachate phase assay (MLPA), in order to measure the action of dissolved pollutants in the aqueous phase. Two hypotheses were formulated to explain the observed difference between MSPA and MLPA results: a real ecotoxicity of the solid phase or the fixation of bacteria to fine particles and/or organic matter. To estimate the latter, flow cytometry analyses were performed with two fluorochromes (known for their ability to stain bacterial DNA), allowing correction of MSPA measurements and generation of new (corrected) IC50. Comparison of results of MLPA with the new IC50 MSPA allows differentiating real ecotoxic and fixation effect in classic MSPA especially for samples with high amount of fines and/or organic matter.     

Presence and fate of coliphages and enteric viruses in three wastewater treatment plants effluents and activated sludge from Tunisia

Purpose

The role of water in the transmission of infectious diseases is well defined; it may act as a reservoir of different types of pathogens. Enteric viruses can survive and persist for a long time in water, maintaining infectivity in many instances. This suggests the need to include virus detection in the evaluation of the microbiological quality of waters.

Methods

In this study, enteric viruses (enteroviruses and hepatitis A virus (HAV)) were investigated by RT-PCR and coliphages (known as indicators of viral contamination) were enumerated with the double-layer technique agar in effluents and sewage sludge from three Tunisian wastewater treatment plants.

Results and discussion

The molecular detection of enteric viruses revealed 7.7% of positive activated sludge samples for enteroviruses. None of the samples was positive for HAV. Molecular virus detection threshold was estimated to be 10³?PFU/100?ml. All samples contained high concentrations of coliphages except those of dry sludge. Reductions in the concentrations of bacteriophages attained by the wastewater treatment plants are of the order of magnitude as reductions described elsewhere. Peak concentrations in raw wastewater were associated with winter rains and suspended materials rate in analysed samples. Our data which is the first in North Africa showed that similar trends of coliphages distribution to other studies in other countries.

Conclusion

No clear correlation between studied enteric viruses and coliphages concentration was proved. Coliphages abundance in collected samples should raise concerns about human enteric viruses transmission as these residues are reused in agricultural fields.