خيارات البحث
النتائج 3131 - 3140 من 3,208
Quality assessment of digested sludges produced by advanced stabilization processes النص الكامل
2015
Braguglia, C. M. | Coors, A. | Gallipoli, A. | Gianico, A. | Guillon, Emmanuel | Kunkel, U. | Mascolo, G. | Richter, E. | Ternes, T. A. | Tomei, M. C. | Mininni, G.
The European Union (EU) Project Routes aimed to discover new routes in sludge stabilization treatments leading to high-quality digested sludge, suitable for land application. In order to investigate the impact of different enhanced sludge stabilization processes such as (a) thermophilic digestion integrated with thermal hydrolysis pretreatment (TT), (b) sonication before mesophilic/thermophilic digestion (UMT), and (c) sequential anaerobic/aerobic digestion (AA) on digested sludge quality, a broad class of conventional and emerging organic micropollutants as well as ecotoxicity was analyzed, extending the assessment beyond the parameters typically considered (i.e., stability index and heavy metals). The stability index was improved by adding aerobic posttreatment or by operating dual-stage process but not by pretreatment integration. Filterability was worsened by thermophilic digestion, either alone (TT) or coupled with mesophilic digestion (UMT). The concentrations of heavy metals, present in ranking order Zn > Cu > Pb > Cr ~ Ni > Cd > Hg, were always below the current legal requirements for use on land and were not removed during the processes. Removals of conventional and emerging organic pollutants were greatly enhanced by performing double-stage digestion (UMT and AA treatment) compared to a single-stage process as TT; the same trend was found as regards toxicity reduction. Overall, all the digested sludges exhibited toxicity to the soil bacterium Arthrobacter globiformis at concentrations about factor 100 higher than the usual application rate of sludge to soil in Europe. For earthworms, a safety margin of factor 30 was generally achieved for all the digested samples.
اظهر المزيد [+] اقل [-]Combined use of PAH levels and EROD activities in the determination of PAH pollution in flathead mullet (Mugil cephalus) caught from the West Black Sea coast of Turkey النص الكامل
2015
Bozcaarmutlu, Azra | Sapmaz, Canan | Kaleli, Gizem | Turna, Sema | Yenisoy-Karakaş, Serpil
The aim of this study was to determine the extent of polycyclic aromatic hydrocarbon (PAH) pollution by measuring PAH levels and 7-ethoxyresorufin-O-deethylase (EROD) activities in flathead mullet (Mugil cephalus) samples caught from the West Black Sea coast of Turkey. The fish samples were caught in August 2008–2011. The levels of 13 PAHs were measured by high-performance liquid chromatography (HPLC) in the liver of fish. Most of the measured PAHs had three rings (low molecular weight). The frequencies of detection of PAHs were higher in fish samples caught from Zonguldak Harbour and Gülüç Stream Mouth than those from Sakarya River Mouth, Amasra and Kefken. EROD activities and cytochrome P4501A (CYP1A) protein level were also measured in the fish liver microsomes. Highly elevated EROD activities and CYP1A levels were measured in the mullet samples caught from Zonguldak Harbour and Gülüç Stream than those from Amasra and Kefken. The detection of PAHs in the liver of fish samples shows recent exposure to PAHs. The chemical analyses of PAHs and EROD activity results together reflected the extent of PAH pollution in the livers of fish caught from the West Black Sea coast of Turkey. The results indicate that Zonguldak Harbour is the most polluted site in the West Black Sea coast of Turkey.
اظهر المزيد [+] اقل [-]Ornamental plants for micropollutant removal in wetland systems النص الكامل
2015
Macci, Cristina | Peruzzi, Eleonora | Doni, Serena | Iannelli, Renato | Masciandaro, Grazia
The objective of this paper was to evaluate the efficiency of micropollutant removal, such as Cu, Zn, carbamazepine, and linear alkylbenzene sulfonates (LAS), through the use of a subsurface vertical flow constructed wetland system with ornamental plants. Zantedeschia aethiopica, Canna indica, Carex hirta, Miscanthus sinensis, and Phragmites australis were selected and planted in lysimeters filled up with gravel. The lysimeters were completely saturated with synthetic wastewater (N 280 mg L⁻¹, P 30 mg L⁻¹, Cu 3.6 mg L⁻¹, Zn 9 mg L⁻¹, carbamazepine 5 μg L⁻¹, linear alkylbenzene sulfonates 14 mg L⁻¹), and the leaching water was collected for analysis after 15, 30, and 60 days in winter-spring and spring-summer periods. Nutrients (N and P) and heavy metals decreased greatly due to both plant activity and adsorption. C. indica and P. australis showed the highest metal content in their tissues and also the greatest carbamazepine and LAS removal. In these plants, the adsorption/degradation processes led to particularly high oxidative stress, as evidenced by the significantly high levels of ascorbate peroxidase activity detected. Conversely, Z. aethiopica was the less efficient plant in metal and organic compound removal and was also less stressed in terms of ascorbate peroxidase activity.
اظهر المزيد [+] اقل [-]Optimizing landfill site selection by using land classification maps النص الكامل
2015
Eskandari, M. | Homaee, M. | Mahmoodi, S. | Pazira, E. | Van Genuchten, M. Th
Municipal solid waste disposal is a major environmental concern throughout the world. Proper landfill siting involves many environmental, economic, technical, and sociocultural challenges. In this study, a new quantitative method for landfill siting that reduces the number of evaluation criteria, simplifies siting procedures, and enhances the utility of available land evaluation maps was proposed. The method is demonstrated by selecting a suitable landfill site near the city of Marvdasht in Iran. The approach involves two separate stages. First, necessary criteria for preliminary landfill siting using four constraints and eight factors were obtained from a land classification map initially prepared for irrigation purposes. Thereafter, the criteria were standardized using a rating approach and then weighted to obtain a suitability map for landfill siting, with ratings in a 0–1 domain and divided into five suitability classes. Results were almost identical to those obtained with a more traditional environmental landfill siting approach. Because of far fewer evaluation criteria, the proposed weighting method was much easier to implement while producing a more convincing database for landfill siting. The classification map also considered land productivity. In the second stage, the six best alternative sites were evaluated for final landfill siting using four additional criteria. Sensitivity analyses were furthermore conducted to assess the stability of the obtained ranking. Results indicate that the method provides a precise siting procedure that should convince all pertinent stakeholders.
اظهر المزيد [+] اقل [-]Endocrine actions of pesticides measured in the Flemish environment and health studies (FLEHS I and II) النص الكامل
2015
Croes, K. | Den Hond, E. | Bruckers, L. | Govarts, E. | Schoeters, G. | Covaci, A. | Loots, I. | Morrens, B. | Nelen, V. | Sioen, I. | Van Larebeke, N. | Baeyens, W.
Within the Flemish Environment and Health studies (FLEHS I, 2002–2006, and FLEHS II, 2007–2012), pesticide exposure, hormone levels and degree of sexual maturation were measured in 14–15-year-old adolescents residing in Flanders (Belgium). In FLEHS II, geometric mean concentrations (with 95 % confidence interval (CI)) of 307 (277–341) and 36.5 ng L⁻¹ (34.0–39.2) were found for p,p′-dichlorophenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB). These values were respectively 26 and 60 % lower than levels in FLEHS I, 5 years earlier. Metabolites of organophosphorus pesticides (OPPs) and of para-dichlorobenzene were measured for the first time in FLEHS II, yielding concentrations of 11.4, 3.27 and 1.57 μg L⁻¹ for the sum of dimethyl- and diethyl phosphate metabolites and 2,5-dichlorophenol (2,5-DCP), respectively. Data on internal exposure of HCB showed a positive correlation with sexual maturation, testosterone and the aromatase index for boys and with free thyroxine (fT4) and thyroid stimulating hormone (TSH) (both boys and girls). For both p,p′-DDE and HCB, a negative association with sexual development in girls was found. The OPP metabolites were negatively associated with sex hormone levels in the blood of boys and with sexual maturation (both boys and girls). The pesticide metabolite 2,5-DCP was negatively correlated with free T4, while a positive association with TSH was reported (boys and girls). These results show that even exposure to relatively low concentrations of pesticides can have significant influences on hormone levels and the degree of sexual maturation in 14–15-year-old adolescents.
اظهر المزيد [+] اقل [-]Unintentional formed PCDDs, PCDFs, and DL-PCBs as impurities in Chinese pentachloronitrobenzene products النص الكامل
2015
Huang, Jun | Gao, Jie | Yu, Gang | Yamazaki, Norimasa | Deng, Shubo | Wang, Bin | Weber, Roland
Pentachloronitrobenzene (PCNB) products have been reported to contain relatively high levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) as impurities. No data was available for Chinese PCNB products which are still produced and used in China. Therefore, we analysed Chinese PCNB products, including two raw pesticides and three formulations available on the market. In all samples, PCDDs, PCDFs, and dioxin-like polychlorinated biphenyls (DL-PCBs) were detected at levels exceeding Japanese regulation limits. The concentrations of PCDDs and PCDFs (0.16 to 0.93 ng TEQ g⁻¹) were lower than the PCNB formulations measured from the Australian market (3.9 ng TEQ g⁻¹). However, the Toxic Equivalent (TEQ) contribution from DL-PCBs (0.7 to 2.5 ng TEQ g⁻¹) to total TEQ was higher compared to PCDDs and PCDFs. This discovery demonstrated that it is necessary to consider the DL-PCBs impurity in organochlorine pesticides and other organochlorine chemicals in particular chlorinated aromatic compounds for adequate risk assessment. In addition to DL-PCBs, other unintentionally POPs—hexachlorobenzene (HCB) (3.7 to 52 ng g⁻¹) and pentachlorobenzene (PeCBz) (0.04 to 0.3 ng g⁻¹) which are listed in the Stockholm Convention—were detected in the PCNB samples. The PCNB production steps were assessed for their unintentional POPs formation potential. Thermolysis of the aromatic compounds using iron chloride (FeCl₃) as catalyst is suggested as relevant production step for (DL-)PCBs formation. Since the levels in the formulated PCNB recalculated to active ingredient were higher compared to the raw pesticide, the formulation process (e.g., milling) may also have had an influence on additional PCDD/Fs and PCBs formation.
اظهر المزيد [+] اقل [-]Proteomic tools to decipher microbial community structure and functioning النص الكامل
2015
Arsène-Ploetze, Florence | Bertin, Philippe N. | Carapito, Christine
Recent advances in microbial ecology allow studying microorganisms in their environment, without laboratory cultivation, in order to get access to the large uncultivable microbial community. With this aim, environmental proteomics has emerged as an appropriate complementary approach to metagenomics providing information on key players that carry out main metabolic functions and addressing the adaptation capacities of living organisms in situ. In this review, a wide range of proteomic approaches applied to investigate the structure and functioning of microbial communities as well as recent examples of such studies are presented.
اظهر المزيد [+] اقل [-]Changes in cellular energy allocation in Enchytraeus crypticus exposed to copper and silver—linkage to effects at higher level (reproduction) النص الكامل
2015
Gomes, Susana I. L. | Soares, Amadeu M. V. M. | Amorim, Mónica J. B.
Changes in cellular energy allocation in Enchytraeus crypticus exposed to copper and silver—linkage to effects at higher level (reproduction) النص الكامل
2015
Gomes, Susana I. L. | Soares, Amadeu M. V. M. | Amorim, Mónica J. B.
Under stressful conditions, organisms often try to detoxify by mobilizing certain energy sources with costs to various functions, e.g. growth or reproduction. Cellular energy allocation (CEA) is a commonly used methodology to evaluate the energetic status of an organism. In the present study, the effects of copper (Cu) and silver (Ag) were evaluated on the total energy budget of Enchytraeus crypticus (Oligochaeta) over periods of exposure (0–2, 2–4 and 4–8 days). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (based on electron transport system activity) being further integrated to obtain the CEA. Results showed that Enchytraeids responded differently to Ag and Cu, mobilizing lipids and proteins in response to Ag and carbohydrates and proteins in response to Cu. Overall, it was possible to distinguish between effect concentrations (reproduction effect concentrations—EC₁₀ and EC₅₀), with EC₁₀ causing an increase in energy consumption (Ec); while for the EC₅₀, the increase in Ec is followed by a steep decrease in Ec, with a corresponding decrease in CEA in the longer exposure periods. These results could be linked with effects at higher levels of biological organization (effects on reproduction) providing evidences that CEA can be used as faster and sensitive endpoints towards metal exposure in E. crypticus.
اظهر المزيد [+] اقل [-]Changes in cellular energy allocation in Enchytraeus crypticus exposed to copper and silver-linkage to effects at higher level (reproduction) النص الكامل
2015 | 1000
Gomes, Susana I. L. | Soares, Amadeu M. V. M. | Amorim, Mónica J. B.
Under stressful conditions, organisms often try to detoxify by mobilizing certain energy sources with costs to various functions, e.g. growth or reproduction. Cellular energy allocation (CEA) is a commonly used methodology to evaluate the energetic status of an organism. In the present study, the effects of copper (Cu) and silver (Ag) were evaluated on the total energy budget of Enchytraeus crypticus (Oligochaeta) over periods of exposure (0–2, 2–4 and 4– 8 days). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (based on electron transport system activity) being further integrated to obtain the CEA. Results showed that Enchytraeids responded differently to Ag and Cu, mobilizing lipids and proteins in response to Ag and carbohydrates and proteins in response to Cu. Overall, it was possible to distinguish between effect concentrations (reproduction effect concentrations—EC10 and EC50), with EC10 causing an increase in energy consumption (Ec); while for the EC50, the increase in Ec is followed by a steep decrease in Ec, with a corresponding decrease in CEA in the longer exposure periods. These results could be linked with effects at higher levels of biological organization (effects on reproduction) providing evidences that CEA can be used as faster and sensitive endpoints towards metal exposure in E. crypticus.
اظهر المزيد [+] اقل [-]Physiological and biochemical responses and microscopic structure changes of Populus tomentosa Carr seedlings to 4-BDE exposure النص الكامل
2015
Cai, Man | Li, Yuling | Li, Yanling | Du, Kejiu
Populus species are very effective in remediation of contaminants. Polybrominated diphenyl ethers (PBDEs) are commonly used as flame retardants and are known to be persistent environmental pollutants. Numerous studies have shown that PBDEs are rising in human tissues and biota. 4-Monobrominated diphenyl ether (4-BDE), one of the less brominated PBDEs, was served as a model compound for biodegradation of lower brominated congeners. The present study was designed to clarify the effects of 4-BDE stress on morphological, physiological, and biochemical impacts of Populus tomentosa Carr in a tissue culture condition. Different concentrations of 4-BDE (3 and 30 mg L⁻¹) were supplied alone or together with 0.5 mg L⁻¹ IBA in tissue culture media. With the concentration increased, 4-BDE caused negative effects on the microscopic structure of roots, stem, and leaves. The leaf color became shallow in low concentration of 4-BDE treatments and appeared albinism with 4-BDE concentration increased. The chlorophyll content and the leaf mass per area of albino leaves reduced significantly. 4-BDE also caused positive effects on the adventitious root differentiation and the biomass below 30 mg L⁻¹. With the 4-BDE treatment time increased (23, 47, and 58 days), the peroxidase (POD) activity displayed the decreasing trend. The proline content decreased first and then increased. Exposure to 4-BDE induced the malondialdehyde (MDA) to increase in leaves. Application of 4-BDE affected the endogenous hormone levels of cuttings in their adventitious roots inducing media. Below 0.3 mg L⁻¹, 4-BDE caused the faint expression of auxin-sensitive DR5::GUS reporter gene in Arabidopsis thaliana. Additionally, P. tomentosa Carr exhibited the better tolerance against 4-BDE in the range of less than 30 mg L⁻¹.
اظهر المزيد [+] اقل [-]Distribution and health risk assessment of mercury in urban street dust from coal energy dominant Huainan City, China النص الكامل
2015
Zheng, Liugen | Tang, Quan | Fan, Jiamin | Huang, Xiaoyu | Jiang, Chunlu | Cheng, Hua
High levels of mercury contamination in urban street dust pose a great threat to human health. In this study, representative urban street dust samples in different urban zones were collected from industrial Huainan City, Eastern China. The distribution and human health risk of Hg in urban street dusts were investigated. In comparison with the soil background Hg values of Huainan and China, the average Hg concentration (0.16 ± 0.14 mg kg⁻¹, n = 50) was significantly elevated, with a variation ranging from 0.02 to 0.56 mg kg⁻¹. Among the seven different urban zones, the industrial district had the highest levels of Hg, potentially deriving predominantly from the dust emissions of the nearby Pingwei coal-fired power plant. In addition, Hg concentrations in dust samples appear to increase with the decrease of particle size. The result of health risk assessment on Hg in these urban street dusts indicated that there was no significant risk of carcinogenesis for the adults living in Huainan city.
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