Effect of ferrate on green algae removal

Green algae Cladophora aegagropila, present in cooling water of thermal power plants, causes many problems and complications, especially during summer. However, algae and its metabolites are rarely eliminated by common removal methods. In this work, the elimination efficiency of electrochemically prepared potassium ferrate(VI) on algae from cooling water was investigated. The influence of experimental parameters, such as Fe(VI) dosage, application time, pH of the system, temperature and hydrodynamics of the solution on removal efficiency, was optimized. This study demonstrates that algae C. aegagropila can be effectively removed from cooling water by ferrate. Application of ferrate(VI) at the optimized dosage and under the suitable conditions (temperature, pH) leads to 100% removal of green algae Cladophora from the system. Environmentally friendly reduction products (Fe(III)) and coagulation properties favour the application of ferrate for the treatment of water contaminated with studied microorganisms compared to other methods such as chlorination and use of permanganate, where harmful products are produced.

     

Sustainable forest management in a mountain region in the Central Western Carpathians,northeastern Slovakia: the role of climate change

European forestry is facing many challenges, including the need to adapt to climate change and an unprecedented increase in forest damage. We investigated these challenges in a Norway spruce-dominated mountain region in Central Europe. We used the model Sibyla to explore forest biomass production to the year 2100 under climate change and under two alternative management systems: the currently applied management (CM), which strives to actively improve the forest’s adaptive capacity, and no management (NM) as a reference. Because biodiversity is thought to have mostly positive effects on the adaptive capacity of forests and on the quality of ecosystem services, we explored how climate change and management affect indicators of biodiversity. We found a differential response across the elevation-climatic gradient, including a drought-induced decrease in biomass production over large areas. With CM, the support of non-spruce species and the projected improvement of their growth increased tree species diversity. The promotion of species with higher survival rates led to a decrease in forest damage relative to both the present conditions and NM. NM preserved the high density of over-matured spruce trees, which caused forest damage to increase. An abundance of dead wood and large standing trees, which can increase biodiversity, increased with NM. Our results suggest that commercial spruce forests, which are not actively adapted to climate change, tend to preserve their monospecific composition at a cost of increased forest damage. The persisting high rates of damage along with the adverse effects of climate change make the prospects of such forests uncertain.     

Synergistic vulnerabilities: climate variability and fire management policy increase farming challenges in southeastern Mexico

Agricultural fire for land preparation is central in the livelihoods of subsistence farmers practicing shifting cultivation. Achieving a good agricultural burn, one in which the biomass is thoroughly consumed within the chosen area, depends on specific weather conditions. Fire use decisions are also shaped by institutions that define the timing and rules for fire use but also constrain the alternatives and shape adaptive capacities. Global and regional climate changes interact with the institutional framing of fire management affecting local fire use and burn outcomes. These effects are documented and analyzed to suggest adaptations to existing governance systems. We examined subsistence farmers’ socio-ecological vulnerability in the Calakmul municipality, located in southeastern Mexico. Using interviews with farmers and government agents, as well as participatory mapping and observation of agricultural burns, we studied fire management knowledge, practices and burn outcomes. Our results describe a continuum of burn outcomes covering good agricultural burns, uncontrolled burns leading to wildfires and “malquemados” literally poorly burned areas. Malquemados represent unsuccessful combustion associated with excess moisture that results in scorched vegetation. We discuss how unexpected early rains trigger effects that cascade through space and the ecological, economic and cultural domains. We argue that fire management has been historically approached from a conservation standpoint yet agricultural fire use and wildfire prevention should also be addressed from a rural development perspective. This shift in fire management would lead to the proper inclusion of the entire array of burn outcomes in studies and policies addressing farmers’ vulnerability amplified by synergistic effects between climate variability and institutional change.     

Effect of the allelochemicals from the macrophyte Egeria densa on the competitive interactions of pelagic and littoral cladocerans

Macrophytes release allelochemicals, which affect pelagic cladocerans such as Daphnia. Using population growth experiments, we analysed the effects of allelochemicals from the macrophyte Egeria densa on the interaction between Daphnia mendotae and three littoral cladocerans (Diaphanosoma birgei, Macrothrix triserialis and Simocephalus mixtus). We found that allelochemicals from E. densa increased the abundance of all the tested cladocerans in spite of the presence of a competitor. This effect was stronger (nearly three to four times higher than in controls) for D. birgei and M. triserialis in the absence of D. mendotae. Independent of the presence of allelochemicals, S. mixtus, but not D. birgei and M. triserialis, reduced the abundance of D. mendotae as compared to controls. The rate of population increase (r) per day was significantly elevated due to the presence of Egeria’s allelochemicals (from 0.07–0.16?d^?1 without allelochemicals against 0.12–0.24?d^?1 with allelochemicals). In our competition experiments, the rates of population increase of the cladocerans were lower than those in single-species cultures when cultured in the absence of allelochemicals. However, in the presence of allelochemicals this trend was not consistent. Thus, the positive effects of Egeria’s allelochemicals over the cladoceran populations may enhance the grazing pressure on phytoplankton.     

Differential blood counting in fish as a non-destructive biomarker of water contamination exposure

Differential white blood cell counting was performed on blood from the fish species Oreochromis niloticus and was used as an in situ indicator of the species’ exposure to contamination. Ten young fish were collected in an area influenced by the discharge of effluents and from a fish farm (control group). The fish were anesthetized and caudal puncture was used to collect the blood. Differential white blood cell counting was performed, as well as the counting of total leukocytes and thrombocytes (in 2000 cells). Physicochemical parameters of the water from both sites were analyzed. The water from the polluted area was found to have high conductivity and low levels of dissolved oxygen, factors that indicate poor environmental quality. Fish collected from the polluted site presented higher percentages of eosinophils and monocytes and fewer thrombocytes because of exposure to pollution and hypoxic conditions. The differential white blood cell count represents a suitable biomarker of environmental health and provides a tool for biomonitoring water quality.     

Pathways of rural change: an integrated assessment of metabolic patterns in emerging ruralities

While rural transformations are nothing new in human history, current processes of rural change occur under multiple forces at an unprecedented pace, involving profound and unexpected changes in land use and users, and rapid transformations in the metabolic patterns of rural systems. The present special section aims to shed light on current drivers and pathways of rural change by analyzing, under a common conceptual and theoretical framework, examples of new ruralities that are emerging as responses across different world regions. Within this context, this introduction presents: (1) common research questions of the six presented cases of rural change; (2) the general theoretical and methodological framework of integrated assessment of societal metabolism adopted to analyze rural systems and (3) the main contributions and conclusions that could be drawn from six context-specific case studies from Asia, Latin America and Europe.     

Advances in the recycling of plastic wastes for metallurgical coke production

This paper aims to provide useful knowledge on the use of plastic wastes as additives to coking blends for the production of metallurgical coke. It focuses on the influence that the composition of plastic wastes has upon the development of coal fluidity, the generation of pressure during the coking process and the quality of the cokes produced in a semipilot oven. Several plastic mixtures of two types of thermoplastics, polyolefins (HDPE, LDPE and PP) and aromatic polymers such as PET, were used. The overall addition rate of plastics to a medium-fluid coal blend was 2 wt%. It is shown that polyolefins, weaker modifiers of coal fluidity, may be employed to maintain coke quality but that they have a negative effect on the generation of coking pressure, while plastics of the aromatic type such as PET, a strong modifier of coal fluidity, can be used to counteract the generation of coking pressure. From the results, it is deduced that the protocol developed is useful for determining the optimum amount of each type of polymer (polyolefins and aromatic polymers) that is needed in order to counteract the generation of pressure during the coking process and to maintain the quality of the cokes.     

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.     

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.