Refine search
Results 1091-1100 of 2,459
Evaluation of Di-1-p-Menthene as Antiozonant on Bel-W3 Tobacco Plants, as Compared with Ethylenediurea
2014
Agathokleous, Evgenios | Saitanis, Costas J. | Papatheohari, Yolanda
Tropospheric ozone (O₃) has long been documented to cause an injury to plants, but a plants’ protectant, widely applicable in agronomical practice, does not exist. We evaluated the potential antiozonate efficacy of the antitranspirant di-1-p-menthene (Vapor Gard) compared with ethylenediurea (EDU) on Bel-W3 tobacco plants. Plants were treated either with water, or by EDU (10, 100, and 500 mg dm⁻³), or by vapor (1, 5, 10, and 50 ml dm⁻³) and were exposed either to O₃-enriched (90 ppb) or O₃-free air, for 12 days and 8 h day⁻¹. EDU when applied at 10 mg dm⁻³did not protect the plants against O₃, but when applied at 100 and 500 mg dm⁻³offered a significant protection to the plants. Vapor, when applied at 1 ml dm⁻³did not protect the plants against O₃, neither by terms of foliar visible injury nor by terms of aboveground biomass. In addition, when applied at 10 and 50 ml dm⁻³caused phytotoxicity to all the plants, which it was expressed as necrotic spots on the leaves’ surface, misshaping of the leaves, or short plants' height.It is obvious that vapor does not protect Bel-W3 tobacco plants against O₃. The antiozonate role of di-1-p-menthene is species-specific and probably occurs only under short-term exposures.
Show more [+] Less [-]Pesticides in River and Tap Water in a Rice Production Area of Niigata, Japan
2014
Narushima, Terukazu | Sato, Takehiko | Goto, Yusuke | Takahashi, Yukio
Water samples collected in 1995 and 2007 from the Shinano and Agano rivers were examined to determine the types and concentrations of pesticides and their effects on tap water in typical rice production areas of Japan. Tap water originating from the Shinano River was also sampled in 2007, in Niigata City, Japan. Pesticides were present in the river and tap water throughout the year. Comparison of 13 pesticides common to both 1995 and 2007 series revealed that the frequency of individual pesticide occurrence and concentrations were decreasing. Riverine pesticides were classified into five groups according to the period of their appearance and changes in concentration. Pesticides were detected at the time of application to, and drainage from, paddy fields. Pesticide concentrations in tap water showed notable decline following rapid sand-filtration combined with granular activated carbon. The detection index (DI) for tap water and Shinano River water did not exceed a value of 1. Herbicides contributed most to the DI.
Show more [+] Less [-]Biodegradation of a Ternary Mixture of Hydrophobic and Hydrophilic VOCs in Trickle Bed Air Biofilters
2014
Zehraoui, Abderrahman | Wendell, David | Sorial, George A.
The main objective of this study was to evaluate the degradation of a ternary mixture of n-hexane, benzene, and methanol fed to two Trickle Bed Air Biofilters (TBABs) designated as “A” and “B”. Both TBABs were loaded with pelletized diatomaceous earth support media and run at an empty bed residence time (EBRT) of 120 s. TBABs “A” and “B” were operated at pH 4 and fed with n-hexane:benzene:methanol (CH:CB:CM) concentrations ratios of 1:3:10 and 1:3:6.6, respectively under different loading rates. The influent total loading rates varied from 39.2 to 117.7 g/m³h and from 32 to 96.4 g/m³h for TBABs “A” and “B”, respectively. In both TBABs, methanol and benzene were the most eliminated volatile organic compounds (VOCs), while the removal of n-hexane was controlled by the VOCs ratios. Higher removal efficiencies were obtained for the VOCs ratio of 1:3:6.6 corresponding to a total VOCs load of 96.4 g/m³h. The addition of VOCs mixture to the TBABs resulted in change of the fungi community within the TBABs as compared to the fungi community when the TBABs were previously receiving only n-hexane as a sole substrate.
Show more [+] Less [-]Random Forests Analysis: a Useful Tool for Defining the Relative Importance of Environmental Conditions on Crown Defoliation
2014
Vitale, Marcello | Proietti, Chiara | Cionni, Irene | Fischer, Richard | De Marco, Alessandra
Defoliation is one of the most important parameters monitored in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). Defoliation is an indicator for forest health and vitality. Conventional statistical analysis shows weak or not significant correlations between tree crown defoliation and climatic conditions or air pollution parameters, because of its high variability. The study aims to evaluate the most important factors among climatic, pollutants (Nₒₓ and NHy) and stand parameters affecting crown defoliation of the main European tree species (Fagus sylvatica, Picea abies, Quercus ilex, Pinus sylvestris and Quercus petraea) through application of a new and powerful statistical classifier, the random forests analysis (RFA). RFA highlighted that tree crown defoliation was mainly related to age in P. abies, to geographic location in F. sylvatica and to air pollution predictors in Q. ilex, while it was similarly linked to meteorological and air pollution predictors in P. sylvestris and Q. petraea. In this study, RFA has proven to be, for the first time, a useful tool to discern the most important predictors affecting tree crown defoliation, and consequently, it can be used for an appropriate forest management.
Show more [+] Less [-]Optimization of Simultaneous Removal of Methylene Blue, Crystal Violet, and Fuchsine from Aqueous Solutions by Magnetic NaY Zeolite Composite
2014
Shirani, Mahboube | Semnani, Abolfazl | Haddadi, Hedayat | Habibollahi, Saeed
In this study, the adsorbent, magnetic NaY zeolite was synthesized for simultaneous removal of three toxic cationic dyes, methylene blue, crystal violet, and fuchsine, from aqueous solutions. The influences of five dominant parameters of pH, temperature, time, initial dyes concentration, and adsorbent mass on dyes adsorption were investigated. The percentage of dye removal was mathematically described as a function of experimental parameters and was modeled through central composite design (CCD). According to the predicted experiments, optimum conditions of 10.3, 50 °C, 45 min, 10 mg L⁻¹, and 46.2 mg, for pH, temperature, time, initial dyes concentration, and adsorbent mass were resulted, respectively. The maximum experimentally achieved dye removal percent of 98.4 ± 0.6, 98.1 ± 0.5, and 98.1 ± 0.3 were obtained, which were close to the percent of model dye removal prediction of 99.0, 98.6, and 98.4 for methylene blue, crystal violet, and fuchsine, respectively. This agreement showed that the central composite design model could ideally make an acceptable estimation of the process.
Show more [+] Less [-]Coexistence of Legionella pneumophila Bacteria and Free-Living Amoebae in Lakes Serving as a Cooling System of a Power Plant
2014
Żbikowska, Elżbieta | Kletkiewicz, Hanna | Walczak, Maciej | Burkowska, Aleksandra
The study was aimed at determining whether potentially pathogenic free-living amoebae (FLA) and Legionella pneumophila can be found in lakes serving as a natural cooling system of a power plant. Water samples were collected from five lakes forming the cooling system of the power plants Pątnów and Konin (Poland). The numbers of investigated organisms were determined with the use of a very sensitive molecular method—fluorescence in situ hybridization (FISH). The result of the present study shows that thermally altered aquatic environments provide perfect conditions for the growth of L. pneumophila and amoebae. The bacteria were identified in the biofilm throughout the entire research period and in the subsurface water layer in July and August. Hartmanella sp. and/or Naegleria fowleri were identified in the biofilm throughout the entire research period.
Show more [+] Less [-]The Development of a Wetland Classification and Risk Assessment Index (WCRAI) for Non-Wetland Specialists for the Management of Natural Freshwater Wetland Ecosystems
2014
Oberholster, P. J. | McMillan, P. | Durgapersad, K. | Botha, A. M. | de Klerk, A. R.
The Wetland Classification and Risk Assessment Index (WCRAI) is based on manifestations of ecological processes in natural wetland ecosystems. The index is hierarchical in structure and is designed to allow identification and rapid assessment at the broadest levels by non wetland experts in different disciplines to manage natural wetlands. From previous studies, landscape ecology has demonstrated the importance of considering landscape context in addition to local site attributes when explaining wetland ecological processes and ecological integrity. The pressures that land uses and activities exert on wetlands generate impacts that affect both the biotic and abiotic characteristics of the surface water column and the surrounding riparian zone. Therefore, human-altered land in a catchment and spatial patterns of surrounding wetlands provide a direct way to measure human impacts and can be correlated with indicators such as water chemistry and biotic variables. The objective of this study was to develop and test the WCRAI so that the index can be used to classify different types of wetlands and to assess their ecological condition (also known as “Eco-status”) under different ecological conditions. The results obtained from the WCRAI were indicative of the integrity of these wetlands when compared to the status of the abiotic and biotic variables measured at each sampling site. From an economical perspective, the WCRAI can play a crucial role in preventing unnecessary degradation of wetlands, hence reducing financial loss through management, restoration, or rehabilitation efforts. The methodology can be applied very easily (due to its simplistic nature) by industry stakeholders to continually monitor these wetlands.
Show more [+] Less [-]Efficient Degradation of Congo Red by Sodium Persulfate Activated with Zero-Valent Zinc
2014
Li, Ying | Li, Hui | Zhang, Jing | Quan, Guixiang | Lan, Yeqing
Zn⁰-activated persulfate as a novel and potential approach to the degradation of azo dyes has hardly been reported. In this study, the effects of initial pH, persulfate concentration, Zn⁰ dosage, and temperature on the decomposition of Congo red (CR), an azo dye, were investigated. The results demonstrated that Zn⁰-activated persulfate could effectively mineralize CR. At the initial pH 5.5 and 25 °C, chemical oxygen demand (COD) and total organic carbon (TOC) in the solution with 95 mg/L CR decreased by approximately 87 and 60 %, respectively, within 3 h. The optimum dosages of persulfate and Zn⁰ were approximately 95 mg/L and 2 g/L, respectively. The highest decolorization efficiency of CR was realized at the initial pH 5.5. Both ·OH and SO₄ ⁻· contributed to the degradation of CR, and the spectra of free radicals showed that SO₄ ⁻· was gradually converted to ·OH with pH increasing from weak acidic to neutral condition.
Show more [+] Less [-]Modeling the Diffusion of Contaminated Site Remediation Technologies
2014
Hou, Deyi | O’Connor, David | Al-Tabbaa, Abir
The present study developed epidemic models to predict the diffusion of remediation technology. Hypotheses were derived from the models and then tested using data collected from a questionnaire survey (n = 223) and a qualitative interview (n = 28) mainly conducted in the USA, UK, and China, as well as data from the US Superfund program. Hypothesis testing results indicate that: (1) tacit knowledge in innovative remedial technologies leads to logistic rather than exponential growth in their adoption, and (2) social-economic and regulatory factors affect the adoption of remediation technologies. For specific remedial technologies adopted in the US Superfund program, it was found that in-situ bioremediation (ISB) has a higher maximum adoption rate than in-situ chemical treatment (ISC), likely due to lower cost and higher social acceptance associated with ISB. The diffusion of ISC was found to be more rapid than that of ISB due to a greater degree of tacit knowledge associated with ISB.
Show more [+] Less [-]Statistical Assessment of the Surface Water Quality Monitoring Network in Saskatchewan
2014
Khalil, Bahaa | Ou, Chunping | Proulx-McInnis, Sandra | St-Hilaire, Andre | Zanacic, Enisa
Surface water quality monitoring is one of the responsibilities of a number of provincial and federal environmental departments in Canada. In Saskatchewan, the Ministry of Environment is responsible for the province water quality monitoring network. The sampling effort was initiated 40 years ago and has been ongoing since, with varying degrees of spatial and temporal coverage. The main objective of the Saskatchewan monitoring network is the assessment of ambient water quality status. In addition, one of the main uses of the generated water quality data is the calculation of a Water Quality Index. The adequacy of the monitoring network to perform these tasks needs to be validated. The objective of this study is to provide a statistical assessment of two of the monitoring network main aspects, the water quality variables and their sampling frequency. A new rationalization approach is applied for the assessment and reselection of water quality variables. The proposed approach provides, in a systematic way, the optimal combinations of variables to continue measuring, variables that may be redundant and could be considered for discontinuance, and variables that may need to be added to the list of variables being measured. The confidence interval around the mean is used as the main criterion for the sampling frequency assessment. A design chart is provided for the sampling frequency assessment, which is easy to use, and provides an initial assessment of the number of samples required to provide a mean value with a predefined error percentage.
Show more [+] Less [-]