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Результаты 2001-2010 из 4,033
A triangular fuzzy TOPSIS-based approach for the application of water technologies in different emergency water supply scenarios
2016
Qu, Jianhua | Meng, Xianlin | You, Huan | You, Hong
Because of the increasing frequency and intensity of unexpected natural disasters, providing safe drinking water for the affected population following a disaster has become a global challenge of growing concern. An onsite water supply technology that is portable, mobile, or modular is a more suitable and sustainable solution for the victims than transporting bottled water. In recent years, various water techniques, such as membrane-assisted technologies, have been proposed and successfully implemented in many places. Given the diversity of techniques available, the current challenge is how to scientifically identify the optimum options for different disaster scenarios. Hence, a fuzzy triangular-based multi-criteria, group decision-making tool was developed in this research. The approach was then applied to the selection of the most appropriate water technologies corresponding to the different emergency water supply scenarios. The results show this tool capable of facilitating scientific analysis in the evaluation and selection of emergency water technologies for enduring security drinking water supply in disaster relief.
Показать больше [+] Меньше [-]Trace metal contamination in commercial fish and crustaceans collected from coastal area of Bangladesh and health risk assessment
2016
Raknuzzaman, Mohammad | Ahmed, Md Kawser | Islam, Md Saiful | Habibullah-Al-Mamun, Md | Tokumura, Masahiro | Sekine, Makoto | Masunaga, Shigeki
Trace metals contamination in commercial fish and crustaceans have become a great problem in Bangladesh. This study was conducted to determine seven trace metals concentration (Cr, Ni, Cu, Zn, As, Cd, and Pb) in some commercial fishes and crustaceans collected from coastal areas of Bangladesh. Trace metals in fish samples were in the range of Cr (0.15 − 2.2), Ni (0.1 − 0.56), Cu (1.3 − 1.4), Zn (31 − 138), As (0.76 − 13), Cd (0.033 − 0.075), and Pb (0.07 − 0.63 mg/kg wet weight (ww)), respectively. Arsenic (13 mg/kg ww) and Zn (138 mg/kg ww) concentrations were remarkably high in fish of Cox’s Bazar due to the interference of uncontrolled huge hatcheries and industrial activities. The elevated concentrations of Cu (400), Zn (1480), and As (53 mg/kg ww) were also observed in crabs of Cox’s Bazar which was considered as an absolutely discrepant aquatic species with totally different bioaccumulation pattern. Some metals in fish and crustaceans exceeded the international quality guidelines. Estimated daily intake (EDI) and target cancer risk (TR) revealed high dietary intake of As and Pb, which was obviously a matter of severe public health issue of Bangladeshi coastal people which should not be ignored and concentrate our views to solve this problem with an integrated approaches. Thus, continuous monitoring of these toxic trace elements in seafood and immediate control measure is recommended.
Показать больше [+] Меньше [-]Changes in bryophyte and lichen communities on Scots pines along an alkaline dust pollution gradient
2016
Degtjarenko, Polina | Marmor, Liis | Randlane, Tiina
Dust pollution can cause a significant damage of environment and endanger human health. Our study aimed to investigate epiphytic lichens and bryophytes in relation to long-term alkaline dust pollution and provide new insights into the bioindicators of dust pollution. We measured the bark pH of Scots pines and the species richness and cover of two cryptogam groups in 32 sample plots in the vicinity of limestone quarries (up to ca. 3 km) in northern Estonia. The bark pH decreased gradually with increasing distance from quarries. We recorded the changes in natural epiphytic communities, resulting in diversified artificial communities on pines near the pollution source; the distance over 2 km from the quarries was sufficient to re-establish the normal acidity of the bark and natural communities of both lichens and bryophytes. The cover of lichens and the number of bryophytes are a more promising indicator of environmental conditions than individual species occurrence. We confirmed previously proposed and suggested new bioindicator species of dust pollution (e.g., Lecidella elaeochroma, Opegrapha varia, Schistidium apocarpum). Limestone quarrying activity revealed a “parapositive” impact on cryptogamic communities, meaning that quarrying might, besides disturbances of natural communities, temporarily contribute to the distribution of locally rare species.
Показать больше [+] Меньше [-]Integrated Geophysical and Geochemical Assessment for the Comprehensive Study of the Groundwater
2016
Kotra, Krishna Kumar | Yedluri, Israel | Prasad, Surendra | Pasupureddi, Sowjanya
Groundwater studies often involve using any one of geophysical, geological, geochemical, or chemical data in the assessment of its characteristics. An integrated method in using all the above had been carried out for more comprehensive and confirmative assessments along the Thandava River basin, India. The geophysical data included the recording of the vertical electrical soundings by Schlumberger array configuration in 50 stations along the basin. Thirty soil samples and rainfall data of 5 years included the geological data. Chemical characterizations for 117 groundwater water samples were carried for two seasons. This study proposes the advantages besides delineating the approach in carrying integrated rather than mere single parameter-based speculative study. This correlative and computer modeling aided study led to an in-depth along with confirmative assessments on various geological, geophysical, and chemical characteristics of the groundwater along with the pollution status. Comprehensive details of groundwater like geomorphology, potential water zones, flow pattern, soil types, geochemical evolution of ions, chemical status, and suitability can be accessed by applying this type of integrated study. Graphical Abstract ᅟ
Показать больше [+] Меньше [-]Efficient Degradation of Methylene Blue by the Nano TiO2-functionalized Graphene Oxide Nanocomposite Photocatalyst for Wastewater Treatment
2016
Wang, Ruibin | Yang, Rendang | Wang, Bin | Gao, Wenhua
Herein, an efficient nano TiO₂-functionalized graphene oxide nanocomposite photocatalyst was readily prepared, using an ordinary solvothermal technique. It was noted that the as-prepared nanocomposite yielded a quadruple degradation capacity of the previously reported P25-graphene composite photocatalyst towards methylene blue (MB). To elucidate this, the Brunauer–Emmett–Teller (BET)-specific surface area, conductivity, and water contact angle measurements were all carried out. It was found out that graphene oxide was endowed with nontrivial photocatalytic activity by increasing its content in the nanocomposite (from 1/100 to 1/9, with respect to the dosage of nano TiO₂). Overall, the nano TiO₂-functionalized graphene oxide nanocomposite is a promising candidate in applications of environment remediation.
Показать больше [+] Меньше [-]Ammonia Emission Quantification from Pig Slurry Using Acid Wet Traps: Evaluation and Optimization of Measurement Frequency
2016
Antezana, W. | Ferrer, P. | Cambra-López, M. | Estellés, F. | Calvet, S.
Standardized measurement protocols are required to reduce ammonia (NH₃) emissions. In vitro measurement of NH₃ emissions consists in trapping the emission from an emitting source in an acidic solution under controlled conditions. The objective of this study was to assess the in vitro NH₃ measurement method from pig slurry with acid wet traps, as regards to the following: (i) the variation between replicates of NH₃ emissions measured in vitro, (ii) the relationships between partial and accumulated emissions, and (iii) the reduction of measurement frequency. For this study, a total of 60 pig slurry samples from different animal types (sows and growing animals) were collected from commercial farms. The coefficient of variation among replicates of accumulated NH₃ emission during 15 days was 6.73 %. Emissions tended to decrease with time, and an average reduction of NH₃ emissions about 16 % was found in the period 96–240 h with respect to the 0–96-h period. However, samples continued emitting considerable amounts of NH₃ after 360 h. Linear regression models allowed predicting emissions accumulated for 15 days using only the first 8 days (R ² > 0.90). Reducing NH₃ measurement frequency (from 24 to 48 h) did not significantly affect measured emissions (P > 0.05). The results of this study confirm that replication of measurements is required and a coefficient of variation of 10 % may be established as quality control requirement. The study also suggests that reducing the duration and frequency of measurements is a tangible option to simplify this methodology.
Показать больше [+] Меньше [-]Antibiotic Resistance in Airborne Bacteria Near Conventional and Organic Beef Cattle Farms in California, USA
2016
Sancheza, Helen M. | Echeverria, Cristina | Thulsiraj, Vanessa | Zimmer-Faust, Amy | Flores, Ariel | Laitz, Madeleine | Healy, Gregory | Mahendra, Shaily | Paulson, Suzanne E. | Zhu, Yifang | Jay, Jennifer A.
Levels of antibiotic resistance genes (ARGs) and the fractions of antibiotic resistant bacteria (ARB) among culturable heterotrophic bacteria were compared in outdoor air near conventional (n = 3) and organic (n = 3) cattle rearing facilities. DNA extracts from filters taken from 18 locations were analyzed by quantitative polymerase chain reaction (qPCR) for five ARGs. At the reference (non-agricultural) site, all genes were below detection. ARGs sul1, bla SHV, erm(B), and bla TEM were more frequently detected and at higher levels (up to 870 copies m⁻³ for bla SHV and 750 copies m⁻³ for sul1) near conventional farms compared to organic locations while the opposite was observed for erm(F) (up to 210 copies m⁻³). Isolates of airborne heterotrophic bacteria (n = 1295) collected from the sites were tested for growth in the presence of six antibiotics. By disk diffusion on a subset of isolates, the fractions of ARB were higher for conventional sites compared to organic farms for penicillin (0.9 versus 0.63), cloxacillin (0.74 versus 0.23), cefoperazone (0.58 versus 0.14), and sulfamethazine (0.50 versus 0.33) for isolates on nutrient agar. All isolates’ ΔA600ₚᵣₑₛ/ΔA600ₐbₛ were measured for each of the six tested antibiotics; isolates from farms downwind of organic sites had a lower average ΔA600ₚᵣₑₛ/ΔA600ₐbₛ for most antibiotics. In general, all three analyses used to indicate microbial resistance to antibiotics showed increases in air samples nearby conventional versus organic cattle rearing facilities. Regular surveillance of airborne ARB and ARGs near conventional and organic beef cattle farms is suggested.
Показать больше [+] Меньше [-]Coupling of Photoactive TiO2 and Impressed Magnetic Field for Phenol Highly Efficient Degradation
2016
He, Chi | Liu, Xiaohe | Ji, Weijiang | Zhao, Jinglian
Synergistic effect of nanosized TiO₂ and impressed magnetic field (MF) was studied by investigating the photocatalytic degradation of phenol at room temperature. The introducing of MF with relatively high intensity (>0.082 T) has obvious promotion effects on phenol degradation rate (C/C ₀), while negative influences of MF on C/C ₀ can be observed under low-intensity MF (<0.044 T). The yield of hydroxyl radicals (·OH) in reaction processes increases with the raising of MF intensity initially and reaches the maximum concentration when the magnetic intensity is 0.082 T. The photoinduced carriers initially decrease until the MF intensity reaches at 0.024 T, and then increase with the increasing of MF intensity. The effects of MF on photoinduced carriers can be explained in terms of the Δg mechanism together with the hyperfine coupling mechanism. Low-intensity MF accelerates the recombination of electrons and holes and suppresses the generation of photoinduced carriers, which further restricts the degradation of phenol. In contrast, the presence of high-intensity MF retards the recombination of hydroxyl radicals and thus enhances the production of ·OH radicals. The generation of hydroxyl radicals is the primary factor in determining the phenol degradation process in the high-intensity MF region. Graphical Abstract Effect of impressed magnetic field on phenol degradation over TiO2 photocatalytic system.
Показать больше [+] Меньше [-]Partitioning of Dichloro-diphenyl-trichloroethane and Its Metabolites Between Artificial Solid Media and Air
2016
Zhang, Yaping | Bi, Erping | Chen, Honghan
Soil–air partitioning is an important diffusive process affecting the environmental fate of organic compounds. In this study, the soil–air partition coefficients (K SA) for dichloro-diphenyl-trichloroethane and its metabolites (designated as DDTs, the sum of p, p′- and o, p′-isomers of DDT, DDD, and DDE) over a temperature range from 5 to 50 °C in artificial solid media were determined by a solid–fugacity meter. The results showed that log K SA gradually increased with soil organic carbon content (f OC). A reversed relationship was observed between log K SA values and the environmental temperatures (T). The enthalpy changes (ΔH SA) indicated that o, p′-isomers required more energy to release from artificial solid media to the gas phase. Moreover, with increasing temperature, the slope of the regression line of log K SA vs. log K OA (octanol–air partition coefficient) was approaching to 1. Based on factors influencing soil–air partitioning and the experimental data, a multiple parameter (T, f OC, and K OA) model was used to predict the K SA values for DDTs.
Показать больше [+] Меньше [-]Preliminary characterization of biosurfactant produced by a PAH-degrading Paenibacillus sp. under thermophilic conditions
2016
Mesbaiah, Fatma Zohra | Eddouaouda, Kamel | Badis, Abdelmalek | Chebbi, Alif | Hentati, Dorra | Sayadi, Sami | Chamkha, Mohamed
The capacities of a biosurfactant producing and polycyclic aromatic hydrocarbon (PAH) utilizing bacterium, namely, strain 1C, isolated from an Algerian contaminated soil, were investigated. Strain 1C belonged to the Paenibacillus genus and was closely related to the specie Paenibacillus popilliae, with 16S rRNA gene sequence similarity of 98.4 %. It was able to produce biosurfactant using olive oil as substrate. The biosurfactant production was shown by surface tension (32.6 mN/m) after 24 h of incubation at 45 °C and 150 rpm. The biosurfactant(s) retained its properties during exposure to elevated temperatures (70 °C), relatively high salinity (20 % NaCl), and a wide range of pH values (2–10). The infrared spectroscopy (FTIR) revealed that its chemical structure belonged to lipopeptide class. The critical micelle concentration (CMC) of this biosurfactant was about 0.5 g/l with 29.4 mN/m. In addition, the surface active compound(s) produced by strain 1C enhanced PAH solubility and showed a significant antimicrobial activity against pathogens. In addition to its biosurfactant production, strain 1C was shown to be able to utilize PAHs as the sole carbon and energy sources. Strain 1C as hydrocarbonoclastic bacteria and its interesting surface active agent may be used for cleaning the environments polluted with polyaromatic hydrocarbons.
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