Estimation and testing for covariance-spectral spatial-temporal models

Environmental and Ecological Statistics - In this paper we explore a covariance-spectral modelling strategy for spatial-temporal processes which involves a spectral approach for time but a...     

Clean electrochemical deposition of calcium carbonate to prevent scale formation in cooling water systems

Calcium carbonate (CaCO₃) deposited in water systems leads to scale formation, decreases flow rate, reduces heat transfer and favors microbial proliferation of toxic bacteria such as Legionella. This issue may be solved by electrochemical deposition, without adding toxic chemicals. Therefore, we studied here the deposition of CaCO₃ by electrochemical reduction of oxygen into hydroxide ions with stainless steel and titanium (Ti) working electrodes. Analysis was done using cyclic voltammetry, chronoamperometry, dynamic impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX) coupled with X-ray diffraction (XRD). Results show that optimal formation of CaCO₃ is done at ?1.2 V with the stainless steel electrode and at ?1.4 V for the Ti electrode. More negative potentials induce the formation of calcite. Using the Ti electrode, we found that aragonite is the major form (82 %), with only one capacitive loop. Using the stainless steel electrode at 1.2 V, we found 47 % of aragonite and 38 % of calcite. Overall, our findings demonstrate the feasibility of the electrochemical deposition of CaCO₃ in cooling water systems, without the addition of any chemical.     

Detection of oxidative stress and DNA damage in freshwater snail <Emphasis Type="Italic">Lymnea leuteola</Emphasis> exposed to profenofos

Extensive production and use of organophosphate pesticide in agriculture, has risen concerned about its ecotoxicity and risk assessment of insecticides, which are more important. Therefore, the present investigation was aimed to study the induction of oxidative stress and DNA damage by organophosphate insecticide profenofos (PFF) in freshwater snail Lymnea luteola (L. luteola). The median lethal value (96 h LC₅₀) of PFF was estimated as 1.26 mg/L for L. luteola in a semi-static system and on the basis of LC₅₀ value three concentrations viz., 0.126 (1/10 of LC₅₀, Sublethal I), 0.63 (1/2 of LC₅₀, Sublethal II) and 0.84 mg/L (2/3 of LC₅₀, Sublethal III) were determined. Snails were exposed to above-mentioned concentrations of PFF along with solvent control (acetone) and negative control for 96 h. The haemolymph was collected at 24 and 96 h of after treatment. In heamolymph of PFF exposed snail, lipid peroxide, glutathione reduced glutathione S transferase and superoxide dismutase activities at the tested concentrations significantly differ from those in the control. The genotoxicity induced in hemocytes of treated snails was measured by alkaline single cell gel electrophoresis assay. The data of this experiment demonstrated significantly enhancement of oxidative stress and DNA damage in the treated snails as compared to controls. Also, we observed statistically significant correlations of ROS with DNA damage (% tail DNA) (R² = 0.9708) for 24 h and DNA damage (R2 = 0.9665) for 96 h.

Results of the current experiment can be useful in risk evaluation of PFF among aquatic organisms. The study confirmed the use of comet assay for in vivo laboratory experiments using freshwater snail for selecting the toxic potential of industrial chemicals and environmental contaminants.

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Individual relocation decisions after tornadoes: a multi‐level analysis

This study examines how multi‐level factors affected individuals' relocation decisions after EF4 and EF5 (Enhanced Fujita Tornado Intensity Scale) tornadoes struck the United States in 2013. A telephone survey was conducted with 536 respondents, including oversampled older adults, one year after these two disaster events. Respondents' addresses were used to associate individual information with block group‐level variables recorded by the American Community Survey. Logistic regression revealed that residential damage and homeownership are important predictors of relocation. There was also significant interaction between these two variables, indicating less difference between homeowners and renters at higher damage levels. Homeownership diminished the likelihood of relocation among younger respondents. Random effects logistic regression found that the percentage of homeownership and of higher income households in the community buffered the effect of damage on relocation; the percentage of older adults reduced the likelihood of this group relocating. The findings are assessed from the standpoint of age difference, policy implications, and social capital and vulnerability.     

Conjugate depths in partially filled sewers and pipes

Environmental Fluid Mechanics - Partially filled pipes have many applications in hydraulic and environmental engineering; such as sewer and storm water collection pipes and circular culverts....     

Effects of previous drying of sediment on root functional traits and rhizoperformance of emerged macrophytes

• Sediment desiccation alters morphological characteristics of aquatic sediment. • Alternation in morphological properties of sediment limiting root characteristics. • Fibrous-rooted macrophytes root properties extra favor nutrients removal. • Thick-rooted macrophytes exhibit higher life-span in two sediment types. Purpose of the current study was to investigate the effects of constantly wet and dried-rewetted sediments on root functional traits of emerged macrophytes and their nutrients removal abilities. It is based on the hypothesis that root characteristics and nutrients removal abilities of plants will be altered in the course of sediment desiccation. Four emerged macrophytes including two fibrous-root plants (Canna indica and Acorus calamus) and two thick-root plants (Alocasia cucullata and Aglaonema commutatum) were investigated for their root functional traits and rhizoperformance in both wet and dried-rewetted sediments. Results showed that sediment desiccation followed by rewetting substantially altered the root functional traits (root surface area, radial oxygen loss, and root activity) of plants due to adverse changes in morphological characteristics (porosity, bulk density, particle density) of dried-rewetted sediments than by wet sediments. Consequently, limited plants growth and removal of nitrogen (N), phosphorus (P) and dissolved organic carbon (DOC) were recorded in dried-rewetted sediments and their pore water than in wet sediments. Radial oxygen loss from plant roots correlated positively with root functional traits, plants growth, and removal of N, P and DOC from pore water and sediment in both sediment types. Among the macrophyte species, the fibrous-root plants having advantages root functional traits, greatly influenced the rhizospheric conditions (pH, dissolved oxygen and redox potential), and demonstrated higher N, P and DOC reduction from both sediment types. While, the thick-rooted plants with thick diameter roots (D > 1 mm) and higher rhizome exhibited longer life-span in both sediment types.     

Dynamic routing with ant system and memory-based decision-making process

Environment Systems and Decisions - Dynamic routing is an essential tool for today’s cities. Dynamic routing problems can be solved by modelling them as dynamic optimization problems (DOPs)....     

CoFe2O4@Methylcelloluse as a New Magnetic Nano Biocomposite for Sonocatalytic Degradation of Reactive Blue 19

Journal of Polymers and the Environment - Reactive Blue 19 (RB19) removal from synthetic textile wastewater was investigated by using a CoFe2O4@methylcellulose (MC) activated with peroxymonosulfate...     

Stakeholder coordination analysis in hazardous waste management: a case study in China

Journal of Material Cycles and Waste Management - Hazardous waste management (HWM) in chemical industrial parks is an important issue related to sustainable development. Previous researches...     

Application of quadratic regression model for Fenton treatment of municipal landfill leachate

The effectiveness of Fenton process in municipal landfill leachate treatment, as a pre- or post-treatment approach, has been demonstrated. However, no general recommendations of universal validity could be made in the term of optimized conditions affecting Fenton process. At the first stage of this study, collected leachate samples from Aradkooh site, Tehran, Iran, were investigated using one-factor-at-a-time method to find out optimum coagulation pH and flocculation time values. Subsequently, the obtained results in addition to data issued previously by the authors were employed to develop a predictive model of the true response surface, namely chemical oxygen demand (COD) removal efficiency. Finally, the main parameters of Fenton procedure, i.e. initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were optimized taking advantage of the above-mentioned quadratic model. The derived second-order model included both significant linear and quadratic terms and seemed to be adequate in predicting responses (R(2)=0.9896 and prediction R(2)=0.6954). It was found that the interaction between initial pH and Fe(2+) dosage has a significant effect on COD removal. While, the optimal [H(2)O(2)]/[Fe(2+)] molar ratio was independent of ferrous ion dosage. The optimum conditions for the maximum COD removal of 50.76% for the parameters of initial pH, [H(2)O(2)]/[Fe(2+)] molar ratio, Fe(2+) dosage, and coagulation pH were found to be 5.8, 8.0, 22,500mg/L, and 8.7 respectively.