خيارات البحث
النتائج 2561 - 2570 من 4,294
Ecological and agriculture impacts of bakery yeast wastewater use on weed communities and crops in an arid environment
2017
Abu-Dieyeh, Mohammed H. | Diab, Mahmoud | Al-Ghouti, Mohammad A.
The goal of this study was to evaluate the impact of using yeast wastewater (YW) on weed communities. The study showed that all ecological parameters including species richness, dispersion, density, frequency, and % of vegetation cover were significantly increased in the site irrigated with YW compared to a natural rain fed site and another site irrigated with fresh water. The vegetation cover (%) was significantly increased by 2-folds in the site irrigated with YW (52%) than the one irrigated with fresh water (27%). Species richness increases to 23 in the site irrigated with yeast wastewater compared to 12 species in natural rain fed site and 7 species in areas irrigated with fresh water. The 10 studied weed species germinated better at 10 and 20% dilutions of baker’s YW. However, only five species achieved few germination (3–25%) at 50% of YW and the two species Sisymbrim irio and Cardariia droba achieved (6–13%) germination using 100% YW. No germination occurred for the crop seeds (tomato, squash, lentil, and barley) at 50 and 100% YW. For tomato, 10 and 20% of YW achieved better germination (82 and 63%, respectively) than the seeds of other species, followed by barley with 80 and 53% of germination. Squash showed the lowest germination percentage with 59 and 42% at 10 and 20% of YW, respectively. Yeast wastewater seems to be crop specific and can affect weed species composition and relative abundances and care should be taken before using the effluent for irrigation of tree plantations and crops.
اظهر المزيد [+] اقل [-]Human health risk assessment due to dietary intake of heavy metals through rice in the mining areas of Singhbhum Copper Belt, India
2017
Giri, Soma | Singh, Abhay Kumar
The study was intended to investigate heavy metal contamination levels in the rice grown in the vicinity of the mining areas of Singhbhum Copper Belt, India. The concentrations of the metals were below the Indian maximum allowable concentrations for food except for Pb, Ni, and Zn at some locations. Principal component analysis extracted three factors explaining 79.1% of the data variability. The extracted factors suggested that the sources of metals in the rice can be attributed to soil, irrigating water, and atmospheric dust deposition. High potential health risks of metal exposure from rice consumption were illustrated based on estimated daily intake (EDI) and target hazard quotient (THQ). The daily intakes of heavy metals for local adults were higher than the tolerable daily intakes provided by WHO in some samples for Cr, Fe, Ni, and V. Considering the geometric mean of the metals in rice samples of the study area, the hazard index (HI) for adult was above unity (3.09). Pb, Cu, and Cr were the key components contributing to potential non-carcinogenic risk. The HI varied from 2.24 to 12.7 among the locations indicating an appreciable heath risk to the consumers of the locally grown rice around the mining areas.
اظهر المزيد [+] اقل [-]Degradation of 5,5-diphenylhydantoin by chlorination and UV/chlorination: kinetics, transformation by-products, and toxicity assessment
2017
Mansor, NurAdawiyah | Tay, KhengSoo
This study investigated the reaction kinetics and mechanism of the degradation of 5,5-diphenylhydantoin (DPH) during conventional chlorination and UV/chlorination. DPH is one of the antiepileptic drugs, which has frequently been detected in the aquatic environment. For chlorination, the second-order rate constant for the reaction between DPH and free active chlorine (FAC) was determined at pH 5 to 8. At pH 6 to 8, the efficiency of chlorination in the removal of DPH was found to be dominated by the reaction involving hypochlorous acid (HOCl). The result also showed that anionic species of DPH was more reactive toward FAC as compared with neutral DPH. For UV/chlorination, the effect of FAC dosage and pH on the degradation of DPH was evaluated. UV/chlorination is a more effective method for removing DPH as compared with conventional chlorination and UV irradiation. The DPH degradation rate was found to increase with increasing FAC concentration. On the other hand, the degradation of DPH was found to be more favorable under the acidic condition. Based on the identified transformation by-products, DPH was found to be degraded through the reaction at imidazolidine-2,4-dione moiety of DPH for both chlorination and UV/chlorination. Toxicity study on the chlorination and UV/chlorination-treated DPH solutions suggested that UV/chlorination is a more efficient method for reducing the toxicity of DPH.
اظهر المزيد [+] اقل [-]Variation in Cd accumulation among radish cultivars and identification of low-Cd cultivars
2017
Dai, Hongwen | Yang, Zhongyi
Heavy metals have serious health consequences and ecosystem impacts. A pot experiment was conducted to investigate the variation of cadmium (Cd) uptake and accumulation among 40 cultivars of radish (Raphanus sativus L.) at three Cd levels, including 0.31 (T1), 0.83 (T2), and 1.13 (T3) mg kg⁻¹. Most of the tested cultivars had higher taproot biomass in the T3 treatment when compared to those in the T1 treatment, indicating a Cd stress-induced growth in radish. Taproot Cd concentrations in 95 and 5% of the tested cultivars were lower than 0.1 mg kg⁻¹ (fresh weight, FW) in the T1 and T2 treatments, respectively; however, there was no cultivar suitable for safe consumption in the T3 treatment. Radish production showed potential risk of Cd pollution as high as some leafy vegetables when grown in the soils where Cd concentration exceeded 0.8 mg kg⁻¹. When compared with Chinese heat-resisting or imported cultivars, Chinese common cultivars had significantly higher taproot Cd concentrations. Three low-Cd cultivars and five high-Cd cultivars were identified. Taproot Cd concentrations showed significant correlations between any two of the three treatments (p < 0.01), suggesting that Cd accumulation in taproot of radish was genotype-dependent.
اظهر المزيد [+] اقل [-]Comparative developmental toxicity of eight typical organic pollutants to red sea bream (Pagrosomus major) embryos and larvae
2017
Zhao, Yanyan | Wang, Xinhong | Lin, Xiaolong | Zhao, Songhe | Lin, Jianqing
The red sea bream (Pagrosomus major) 48-h embryo-larval bioassay was used to assess and compare the developmental toxicities of eight typical organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), organophosphorus pesticides, polychlorinated biphenyls (PCBs) and alkylphenol. Toxicological endpoints such as survival rates of P. major embryos or larvae and the rates of hatching and of malformation (oedema, condensed blood, spinal curvatures or eye abnormalities) were noted and described within 48 h of exposure. The LC₅₀, EC₅₀, no-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) were calculated, based on the dose-response relationship. The results showed that exposures to all of the selected organic pollutants except for methyl parathion produced acute toxic effects on P. major embryos and larvae, at different levels of exposure. The levels of acute toxicity of the eight typical organic pollutants for P. major embryos and larvae showed the following trend: benzo(a)pyrene > malathion > PCB 126 > pyrene > nonylphenol > phenanthrene > monocrotophos > methyl parathion. However, the larvae were more sensitive to these pollutants than embryos, according to the calculated LC₅₀, EC₅₀, NOEC and LOEC. This increased sensitivity of larvae could have resulted from losing the natural barrier function of the egg shell membrane. Benzo(a)pyrene, malathion, nonylphenol and monocrotophos delayed the development of P. major for both embryos and larvae, and decreased the hatching rate of the embryos. These results implied that the development of fish embryos and larvae could serve as potential biomarkers for evaluating organic contamination in the aquatic environment. The marine economic fish P. major was more sensitive to PAHs than the model fish, marine medaka (Oryzias melastigma). The estimated safe concentrations (SCs) for marine economic fish, as determined in our research, could provide a reference for the formulation of water quality criteria.
اظهر المزيد [+] اقل [-]Removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) from wastewaters by zero-valent iron (ZVI): predominant removal mechanism for effective SDBS removal
2017
Takayanagi, Akari | Kobayashi, Maki | Kawase, Yoshinori
Mechanisms for removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in wastewaters by zero-valent iron (ZVI) were systematically examined. The contributions of four removal mechanisms, i.e., reductive degradation, oxidative degradation, adsorption, and precipitation, changed significantly with solution pH were quantified and the effective removal of SDBS by ZVI was found to be attributed to the adsorption capability of iron oxides/hydroxides on ZVI surface at nearly neutral pH instead of the degradation at acidic condition. The fastest SDBS removal rate and the maximum TOC (total organic carbon) removal efficiency were obtained at pH 6.0. The maximum TOC removal at pH 6.0 was 77.8%, and the contributions of degradation, precipitation, and adsorption to TOC removal were 4.6, 14.9, and 58.3%, respectively. At pH 3.0, which is an optimal pH for oxidative degradation by the Fenton reaction, the TOC removal was only 9.8% and the contributions of degradation, precipitation, and adsorption to TOC removal were 2.3, 4.6, and 2.9%, respectively. The electrostatic attraction between dodecyl benzene sulfate anion and the iron oxide/hydroxide layer controlled the TOC removal of SDBS. The kinetic model based on the Langmuir-Hinshelwood/Eley-Rideal approach could successfully describe the experimental results for SDBS removal by ZVI with the averaged correlation coefficient of 0.994. ZVI was found to be an efficient material toward the removal of anionic surfactant at nearly neutral pH under the oxic condition.
اظهر المزيد [+] اقل [-]Source analysis of organic matter in swine wastewater after anaerobic digestion with EEM-PARAFAC
2017
Zeng, Zhuo | Zheng, Ping | Ding, Aqiang | Zhang, Meng | Abbas, Ghulam | Li, Wei
Swine wastewater is one of the most serious pollution sources, and it has attracted a great public concern in China. Anaerobic digestion technology is extensively used in swine wastewater treatment. However, the anaerobic digestion effluents are difficult to meet the discharge standard. The results from batch experiments showed that plenty of refractory organic matter remained in the effluents after mesophilic anaerobic digestion for 30 days. The effluent total COD (tCOD) and soluble COD (sCOD) were 483 and 324 mg/L, respectively, with the sCOD/tCOD ratio of 0.671. Fluorescence excitation–emission matrix (EEM) coupled with parallel factor analysis (PARAFAC) revealed that the dissolved organic matter in the effluents was tryptophan-like substance, humic acid substance, and fulvic acid substance. Based on the appearance time during anaerobic digestion, tryptophan-like substance and humic acid substance were inferred to originate from the raw swine wastewater, and the fulvic acid substance was inferred to be formed in the anaerobic digestion. This work has revealed the source of residual organic matter in anaerobic digestion of swine wastewater and has provided some valuable information for the post-treatment.
اظهر المزيد [+] اقل [-]Occurrence of 25 pharmaceuticals in Taihu Lake and their removal from two urban drinking water treatment plants and a constructed wetland
2017
Hu, Xia-Lin | Bao, Yi-Fan | Hu, Jun-Jian | Liu, You-Yu | Yin, Da-Qiang
Pharmaceuticals in drinking water sources have raised significant concerns due to their persistent input and potential human health risks. The seasonal occurrence of 25 pharmaceuticals including 23 antibiotics, paracetamol (PAR), and carbamazepine (CMZ) in Taihu Lake was investigated; meanwhile, the distribution and removal of these pharmaceuticals in two drinking water treatment plants (DWTPs) and a constructed wetland were evaluated. A high detection frequency (>70%) in the Taihu Lake was observed for nearly all the 25 pharmaceutics. Chlortetracycline (234.7 ng L⁻¹), chloramphenicol (27.1 ng L⁻¹), erythromycin (72.6 ng L⁻¹), PAR (71.7 ng L⁻¹), and CMZP (23.6 ng L⁻¹) are compounds with both a high detection frequency (100%) and the highest concentrations, suggesting their wide use in the Taihu Basin. Higher concentrations of chloramphenicols, macrolides, PAR, and CMZP were observed in dry season than in wet season, probably due to the low flow conditions of the lake in winter and the properties of pharmaceuticals. The overall contamination levels of antibiotic pharmaceutics (0.2–74.9 ng L⁻¹) in the Taihu Lake were lower than or comparable to those reported worldwide. However, for nonantibiotic pharmaceutics, PAR (45.0 ng L⁻¹) and CMZP (14.5 ng L⁻¹), significantly higher concentrations were observed in the Taihu Lake than at a global scale. High detection frequencies of 25 pharmaceuticals were observed in both the two DWTPs (100%) and the wetland (>60%) except for florfenicol and sulfapyridine. The removal efficacies of the studied pharmaceuticals in DWTP B with advanced treatment processes including ozonation and granular activated carbon filtration (16.7–100%) were superior to DWTP A with conventional treatment processes (2.9–100%), except for sulfonamides. Wetland C with the constructed root channel technology was efficient (24.2–100%) for removing most pharmaceuticals. This work suggests that the application of cost-effective technologies such as constructed wetlands should be considered as an efficient alternative for removing pharmaceuticals from water supply sources.
اظهر المزيد [+] اقل [-]The biological response chain to pollution: a case study from the “Italian Triangle of Death” assessed with the liverwort Lunularia cruciata
2017
Basile, Adriana | Loppi, Stefano | Piscopo, Marina | Paoli, Luca | Vannini, Andrea | Monaci, Fabrizio | Sorbo, Sergio | Lentini, Marco | Esposito, Sergio
The liverwort Lunularia cruciata, known for being a species tolerant to pollution able to colonize urban areas, was collected in the town of Acerra (South Italy) to investigate the biological effects of air pollution in one of the three vertices of the so-called Italian Triangle of Death. The ultrastructural damages observed by transmission electron microscopy in specimens collected in Acerra were compared with samples collected in the city center of Naples and in a small rural site far from sources of air pollution (Riccia, Molise, Southern Italy). The biological response chain to air pollution was investigated considering vitality, photosynthetic efficiency, heat shock protein 70 (Hsp70) induction and gene expression levels, and chlorophyll degradation and related ultrastructural alterations. Particularly, a significant increment in Hsp70 expression and occurrence, and modifications in the chloroplasts’ ultrastructure can be strictly related to the environmental pollution conditions in the three sites. The results could be interpreted in relation to the use of these parameters as biomarkers for environmental pollution.
اظهر المزيد [+] اقل [-]Evaluation of human thermal comfort ranges in urban climate of winter cities on the example of Erzurum city
2017
Toy, Süleyman | Kántor, Noémi
Human thermal comfort conditions can be evaluated using various indices based on simple empirical approaches or more complex and reliable human-biometeorological approaches. The latter is based on the energy balance model of the human body, and their calculation is supplemented with computer software. Facilitating the interpretation of results, the generally applied indices express the effects of thermal environment in the well-known temperature unit, just like in the case of the widely used index, the physiologically equivalent temperature (PET). Several studies adopting PET index for characterizing thermal components of climate preferred to organize the resulted PET values into thermal sensation categories in order to demonstrate the spatial and/or temporal characteristics of human thermal comfort conditions. The most general applied PET ranges were derived by Central European researchers, and they are valid for assumed values of internal heat production of light activity and thermal resistance of clothing representing a light business suit. Based on the example of Erzurum city, the present work demonstrates that in a city with harsh winter, the original PET ranges show almost purely discomfort and they seem to be less applicable regarding cold climate conditions. Taking into account 34-year climate data of Erzurum, the annual distribution of PET is presented together with the impact of application of different PET categorization systems, including 8°- and 7°-wide PET intervals. The demonstrated prior analyses lack any questionnaire filed surveys in Erzurum. Thus, as a next step, detailed field investigations would be required with the aim of definition of new PET categorization systems which are relevant for local residents who are adapted to this climatic background, and for tourists who may perform various kinds of winter activities in Erzurum and therefore may perceive the thermal environment more comfortable.
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