Affiner votre recherche
Résultats 1971-1980 de 3,208
PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities Texte intégral
2015
Ren, Chen | Wu, Yaketon | Zhang, Shuo | Wu, Liangliang | Liang, Xiao-Guo | Chen, Tian-Hu | Zhu, Cheng-Zhu | Sojinu, Samuel O | Wang, Ji-Zhong
In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (Σ₂₈PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY). The predominant PAHs are high molecular weight (HMW) homologous for all samples; as a result, industrial wastewater from a steel company is expectedly the key source of PAHs in ENF, while coke consumption would be the important source of PAHs at other three sampling sites. Vertical distribution of PAHs in the sediment cores could be explained by the local social and economic activities. Furthermore, a minor variation of PAH composition in the sediment core could be justified by the stable structure of energy consumption in the Anhui Province. These results justify the need for further enhancement of industrial wastewater treatment and development of renewable energies which are the key factors on the control of PAH pollution in China.
Afficher plus [+] Moins [-]Refractory organic pollutants and toxicity in pulp and paper mill wastewaters Texte intégral
2015
Lindholm-Lehto, Petra C. | Knuutinen, Juha S. | Ahkola, Heidi S. J. | Herve, Sirpa H.
This review describes medium and high molecular weight organic material found in wastewaters from pulp and paper industry. The aim is to review the versatile pollutants and the analysis methods for their determination. Among other pollutants, biocides, extractives, and lignin-derived compounds are major contributors to harmful effects, such as toxicity, of industrial wastewaters. Toxicity of wastewaters from pulp and paper mills is briefly evaluated including the methods for toxicity analyses. Traditionally, wastewater purification includes mechanical treatment followed by chemical and/or biological treatment processes. A variety of methods are available for the purification of industrial wastewaters, including aerobic and anaerobic processes. However, some fractions of organic material, such as lignin and its derivatives, are difficult to degrade. Therefore, novel chemical methods, including electrochemical and oxidation processes, have been developed for separate use or in combination with biological treatment processes.
Afficher plus [+] Moins [-]Assessment of the non-protein amino acid BMAA in Mediterranean mussel Mytilus galloprovincialis after feeding with estuarine cyanobacteria Texte intégral
2015
Baptista, Mafalda S. | Vasconcelos, Rita G. W. | Ferreira, Paula C. | Almeida, C. Marisa R. | Vasconcelos, Vitor M.
To determine whether 2-amino-3-methylaminopropanoic acid (BMAA) could be taken up by marine organisms from seawater or their diet mussels Mytilus galloprovincialis, collected from the North Atlantic Portuguese shore, were exposed to seawater doped with BMAA standard (for up to 48 h) or fed with cyanobacteria (for up to 15 days). Mussels were able to uptake BMAA when exposed to seawater. Mussels fed with cyanobacteria Synechocystis salina showed a rise in BMAA concentration during feeding and a decline in concentration during the subsequent depuration period. Cells from the gills and hepatopancreas of mussels fed with S. salina showed lessened metabolic activity in mussels fed for longer periods of time. A hot acidic digestion (considered to account for total BMAA) was compared with a proteolytic digestion, using pepsin, trypsin and chymotrypsin. The latter was able to extract from mussels approximately 30 % of total BMAA. Implications for BMAA trophic transfers in marine ecosystems are discussed.
Afficher plus [+] Moins [-]Effect of lambda cyhalothrin on Calothrix sp. (GUEco 1001), an autochthonous cyanobacterium of rice fields of Brahmaputra floodplain Texte intégral
2015
Gupta, Kiran | Baruah, P. P.
Pesticide contamination in the rice fields has manifested into a serious global environmental concern. Application of pesticides in the rice fields has deleterious effects on non-target organisms including nitrogen-fixing cyanobacteria which help to maintain the rice field fertility. In the present research endeavor, the effect of lambda cyhalothrin (5 % EC), a synthetic pyrethroid insecticide, has been studied on the growth and pigments content of Calothrix sp. (GUEco 1001), an indigenous strain isolated from rice grown areas of Brahmaputra floodplain. To study the toxic effect of lambda cyhalothrin, the test organism was exposed to varying concentrations of the insecticide i.e., 20 ppm, 40 ppm, 80 ppm, and 160 ppm based upon the determination of LC₅₀ for a period of 20 days. The result obtained in the laboratory showed a progressive decrease in the growth and pigments content by the test organism with increasing concentrations of the lambda cyhalothrin against time dose-dependent manner. At high dose (160 ppm), the test organism showed significant decrease in dry weight biomass (54.5 %), chlorophyll-a (68 %), carotenoids (38 %), phycocyanin (80 %), and nitrogen contents (55 %) over the control. A little but insignificant stimulatory effect on growth and chlorophyll-a contents was recorded in 20 ppm treatment of the insecticide that, however, was reversed in case of carotenoids and phycocyanin contents.
Afficher plus [+] Moins [-](NH4) 2SO 4 recovery from liquid side streams Texte intégral
2015
Boehler, Marc Anton | Heisele, Alexander | Seyfried, Alexander | Grömping, Markus | Siegrist, Hansruedi
Two methods of recovering nitrogen from liquid side streams are presented in this paper. The first method was demonstrated at an ammonia stripping plant treating 5–7 m³/h sludge water at the wastewater treatment plant (WWTP) Kloten-Opfikon (CH). In addition to the usual stripping and scrubbing columns, a third column had been added in order strip CO₂, thus reducing the NaOH-demand of the subsequent ammonia stripping. At first, just the stripping plant was put into operation and optimized without any pre-treatment of the supernatant. Next, the CO₂-stripper column was activated and optimized by gas measurements to minimize free ammonia losses, heat losses, and energy consumption. Key operational aspects of the plant were evaluated. Finally, up to 1.4 m³/h source-separated urine was successfully fed into the stripping facility. The second ammonia removal method using hydrophobic hollow fiber membranes was tested in two small pilot systems by different manufacturers in 2012 and 2013 at WWTP Neugut. In this technology, free ammonia gas in the sludge liquid diffuses at pH >9.3 from the sludge liquid through the air-filled pores of the microporous hydrophobic membrane into concentrated sulfuric acid flowing through the hollow fibers, forming ammonium sulfate. The small pore size and the hydrophobic nature of the membrane prevent the liquid phase from entering into the pores due to the surface tension effect. Practical experience regarding operational parameters like wastewater flow rate, pH, temperature, ammonia concentration, fouling and precipitations processes, optimal flow schemes, and process configurations was collected.
Afficher plus [+] Moins [-]Columnar and ground-level aerosol optical properties: sensitivity to the transboundary pollution, daily and weekly patterns, and relationships Texte intégral
2015
Perrone, M. R. | Romano, S. | Orza, J. A. G.
Columnar and ground-level aerosol optical properties co-located in space and time and retrieved from sun/sky photometer and nephelometer measurements, respectively, have been analyzed to investigate the impact of local and transboundary pollution, to analyze their relationships, and hence to contribute to the aerosol load characterization over the Central Mediterranean. The aerosol optical depth (AOD) at 440 nm, the Ångström exponent (Å) calculated from the AOD at 440 and 675 nm, and the asymmetry parameter (g cₒₗ) at 440 nm represent the investigated columnar aerosol parameters. The scattering coefficient (σ ₚ) at 450 nm, the scattering Ångström exponent (å) calculated from σ ₚ at 450 and 635 nm, and the asymmetry parameter (g) at 450 nm are the corresponding ground-level parameters. It is shown that the columnar and ground-level aerosol properties were significantly and similarly affected by the main airflows identified with backtrajectory cluster analysis. The yearly averaged daily evolution of σ ₚ, å, and g was fairly correlated to the one of the AOD, Å, and g cₒₗ , respectively. These results indicate that the aerosol particles were on average characterized by similar yearly averaged optical properties up to the ground level. In particular, the yearly means of columnar and ground-level Ångström exponents, 1.3 ± 0.4 and 1.1 ± 0.4, respectively, which are close to one, reveal a coarse-mode aerosol contribution in addition to the fine-mode particle contribution up to the ground level. Hourly means, day-by-day, and seasonal daily patterns of ground-level parameters were, however, very weakly correlated with the corresponding columnar parameters. The large impact of the local meteorology on the daily evolution of the ground-level aerosol properties, which makes the impact of long-range transported particles less apparent, was mainly responsible for these last results. It has also been found that columnar Ångström exponents much smaller than one may not be linked to å values smaller than 1. This may occurs when coarse-mode particle plumes, advected at high altitudes, do not penetrate inside the planetary boundary layer. Ångström exponents smaller than 1 are due to a significant contribution of coarse-mode particles as dust particles. Therefore, it is shown that å represents one of the best parameters to infer the contribution of coarse-mode particles at the ground level. The daily evolution of the aerosol properties referring to working days (Monday to Friday) and Sunday and the weekly cycle have suggested that the aerosol source contributions varied during the weekends. In particular, the AOD was characterized by a negative weekly cycle (higher AOD values during the weekend than during the weekdays), the Sunday σ ₚ daily mean was 11 % larger than the Monday value, and å reached the highest value on Sunday. The impact up to the ground level of the weekdays’ transboundary pollution, which reaches the monitoring site during the weekends, has likely contributed to these results.
Afficher plus [+] Moins [-]Distribution and chemical forms of copper in the root cells of castor seedlings and their tolerance to copper phytotoxicity in hydroponic culture Texte intégral
2015
Kang, Wei | Bao, Jianguo | Zheng, Jin | Hu, Hongqin | Du, Jiangkun
The subcellular localization and chemical forms of copper in castor (Ricinus communis L.) seedlings grown in hydroponic nutrient solution were identified by chemical extraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The wild castor seeds were harvested from an abandoned copper mine in Tonglu Mountain, Daye City of Hubei Province, China. The results revealed that (1) the seedlings grew naturally in MS liquid medium with 40.00 mg kg⁻¹CuSO₄, in which the seedling growth rate and biomass index were 0.14 and 1.23, respectively, which were the highest values among all the treatments. The copper content in castor seedlings increased along with elevated CuSO₄concentration in the medium, reaching a maximum value of 16 570.12 mg kg⁻¹(DW) when exposed to 60.00 mg L⁻¹CuSO₄, where 91.31 % of the copper was accumulated in roots. (2) The copper existed in various chemical forms in the roots of the castor seedlings. Copper of 67.66 % was extracted from the components of cell walls, such as exchangeable acidic polar compounds, cellulose and lignin, protein and pectin, and less concentrated in cell cytoplasm and nuclei. (3) Furthermore, the root cell walls were thickened when the castor seedlings exposed to CuSO₄, with a large amount of high-density electron bodies, attached to the thickened cell walls. In the cell walls, most copper was bound to the carboxyl (−COOH) and hydroxyl (−OH) groups of acidic polar compounds, cellulose, hemicellulose, and polysaccharides. The conclusion showed that castor exhibited a strong tolerance to copper, the copper were accumulated mainly in the root cell, the root cell walls of castor were the major location of patience and detoxification in copper stress.
Afficher plus [+] Moins [-]Genotoxic and hematological parameters in Colossoma macropomum (Pisces, Serrasalmidae) as biomarkers for environmental impact assessment in a protected area in northeastern Brazil Texte intégral
2015
Fortes Carvalho Neta, Raimunda Nonata | Pinheiro Sousa, Débora Batista | de Macêdo Sobrinho, Inaldo Carvalho | Yarbrough Horton, Emily | Almeida, Zafira da Silva de | Tchaicka, Lígia | de Sousa, Alana Lislea
Genotoxic and hematological parameters in tambaqui (Colossoma macropomum), a native freshwater fish, were used as biomarkers to assess exposure to environmental stressors within the Maracanã Protected Area of Maranhão State, Brazil. Fish were sampled at two sites—Serena Lagoon (control) and Ambude River—on four occasions (dry and rainy season), and biometric data (length and weight) recorded and blood collected from all fish for analysis. Erythrocyte indices—mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration—were calculated. Blood samples were stained with Giemsa and acridine orange, and microscopically examined for micronuclei and morphological nuclear abnormalities. Micronuclei were observed in fish from both sites, although the frequency was significantly higher in fish from the Ambude River and morphological nuclear abnormalities were only observed in fish from the Ambude River. More morphological nuclear abnormalities and a larger number of micronuclei were observed in erythrocytes stained with acridine orange compared with those stained with Giemsa. On average, erythrocyte indices were lower in fish from the Ambude River than from the Serena Lagoon. The results confirm that genotoxic and hematological parameters in C. macropomum can be used as indicators of environmental health and could be valuable tools for monitoring environmental conditions within protected areas.
Afficher plus [+] Moins [-]Cadmium exposure and risk of pancreatic cancer: a meta-analysis of prospective cohort studies and case–control studies among individuals without occupational exposure history Texte intégral
2015
Chen, Cheng | Xun, Pengcheng | Nishijo, Muneko | Sekikawa, Akira | He, Ka
Pancreatic cancer is one of the most deadly types of cancer for both genders. Classified as a human carcinogen, cadmium has been related to diverse cancers. However, the association between cadmium exposure and the risk of pancreatic cancer is still unclear. We quantitatively reviewed the observational studies on the association of cadmium exposure with pancreatic cancer risk among individuals without occupational exposure history published through July 2014 in PubMed by using a fixed-effect model. Four prospective cohort studies (112,934 participants with 335 events) and two case–control studies (177 cases and 539 controls) were identified. The summarized relative risk (RR) with a 95 % confidence interval (CI) was 2.05 (95 % CI = 1.58–2.66), comparing the highest to the lowest category of cadmium exposure. This positive association persisted in men (RR = 1.78, 95 % CI = 1.04–3.05) but not in women (RR = 1.02, 95 % CI = 0.63–1.65). Further research is needed to provide more solid evidence on the association of cadmium exposure with pancreatic cancer risk and to elucidate the underlying biological mechanism of the potential gender difference.
Afficher plus [+] Moins [-]Investigations on sediment toxicity of German rivers applying a standardized bioassay battery Texte intégral
2015
Hafner, Christoph | Gartiser, Stefan | Garcia-Käufer, Manuel | Schiwy, Sabrina | Hercher, Christoph | Meyer, Wiebke | Achten, Christine | Larsson, Maria | Engwall, Magnus | Keiter, Steffen | Hollert, Henner
River sediments may contain a huge variety of environmental contaminants and play a key role in the ecological status of aquatic ecosystems. Contaminants adsorbed to sediments and suspended solids may contribute directly or after remobilization to an adverse ecological and chemical status of surface water. In this subproject of the joint research project DanTox, acetonic Soxhlet extracts from three German river sediments from the River Rhine (Altrip and Ehrenbreitstein with moderate contamination) and River Elbe (Veringkanal Hamburg heavily contaminated) were prepared and redissolved in dimethyl sulfoxide (DMSO). These extracts were analyzed with a standard bioassay battery with organisms from different trophic levels (bacteria, algae, Daphnia, fish) as well as in the Ames test and the umuC test for bacterial mutagenicity and genotoxicity according to the respective OECD and ISO guidelines. In total, 0.01 % (standard) up to 0.25 % (only fish embryo test) of the DMSO sediment extract was dosed to the test systems resulting in maximum sediment equivalent concentrations (SEQ) of 2 up to 50 g l⁻¹. The sediment of Veringkanal near Hamburg harbor was significantly more toxic in most tests compared to the sediment extracts from Altrip and Ehrenbreitstein from the River Rhine. The most toxic effect found for Veringkanal was in the algae test with an EᵣC₅₀ (72 h) of 0.00226 g l⁻¹ SEQ. Ehrenbreitstein and Altrip samples were about factor 1,000 less toxic. In the Daphnia, Lemna, and acute fish toxicity tests, no toxicity at all was found at 2 g l⁻¹ SEQ. corresponding to 0.01 % DMSO. Only when increasing the DMSO concentration the fish embryo test showed a 22-fold higher toxicity for Veringkanal than for Ehrenbreitstein and Altrip samples, while the toxicity difference was less evident for the Daphnia test due to the overlaying solvent toxicity above 0.05 % dimethyl sulfoxide (DMSO). The higher toxicities observed with the Veringkanal sample are supported by the PAH and PCB concentrations analyzed in the sediments. The sediment extracts of Altrip and Veringkanal were mutagenic in the Ames tester strain TA98 with metabolic activation (S9-mix). The findings allow a better ecotoxicological characterization of the sediments extensively analyzed in all subprojects of the DanTox project (e.g., Garcia-Kaeufer et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3894-4 , 2014; Schiwy et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3185-0 , 2014; Hollert and Keiter 2015). In the absence of agreed limit values for sediment extracts in standard tests, further data with unpolluted reference sediments are required for a quantitative risk assessment of the investigated polluted sediments.
Afficher plus [+] Moins [-]