خيارات البحث
النتائج 2111 - 2120 من 2,512
Comparison of species sensitivity distributions for species from China and the USA النص الكامل
2014
Wang, Xiaonan | Zhenguang, Yan | Liu, Zhengtao | Zhang, Cong | Wang, Weili | Li, Handong
China has recently commenced water quality criteria (WQC) research using the species sensitivity distribution (SSD) method; however, it is difficult to obtain sufficient native species toxicity data for thousands of contaminants. In this study, the feasibility of using non-native toxicity data in deriving native WQC was analyzed. We constructed SSDs based on acute toxicity data of species from China and the USA for eight priority pollutants, and compared the sensitivities of different taxonomic groups between the two countries. The results showed that the SSD method of log-logistic distribution fit the toxicity data of different taxa well. The comparison of sensitivity distribution and hazardous concentration for 5 % of the species and 50 % of the species showed that there was no significant difference between Chinese and American taxa. It could be feasible to use toxicity data from the USA to provide a temporary way to protect organisms in China in emergency situations or for management of priority pollutants when native toxicity data are lacking.
اظهر المزيد [+] اقل [-]Characterization of the interactions between tetracycline antibiotics and microbial extracellular polymeric substances with spectroscopic approaches النص الكامل
2014
Song, Chao | Sun, Xue-Fei | Xing, Su-Fang | Xia, Peng-Fei | Shi, Yi-Jing | Wang, Shu-Guang
The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV–visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation–emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces.
اظهر المزيد [+] اقل [-]Characterization of springtime airborne particulate matter-bound reactive oxygen species in Beijing النص الكامل
2014
Liu, Qingyang | Zhang, Yuanxun | Liu, Yanju | Zhang, Meigen
Epidemiologic studies have suggested that particulate matter (PM)-associated adverse health effects are related to particle composition. To study the toxicological characteristics of dust storm, airborne PM₁₀ was collected at two sites in Beijing from March to May 2012. The production of reactive oxygen species (ROS), quantified by dithiothreitol (DTT), was used to measure the PM-induced oxidative potential. Two dust storm (DS) samples were monitored during the sampling period: one happened on March 28th (DS1) and the other one was on April 28th (DS2). The backward trajectory results showed that both events originated from Inner Mongolia and Mongolia, respectively. The increased trends of ROS activities during the dust storm episode in PM₁₀ were observed for all the dust storms owing to a higher concentration of water-soluble components for all the PM₁₀ samples compared to nondust storm ones. Interestingly, the correlations between DTT consumption with water-soluble species yield interesting results about the spatial variability of redox activity between sites. In particular, a tracer of soil suspension, namely Fe, contributed the most fraction to ROS variability in the urban background site. Water-soluble organic carbon (WSOC) made the highest contribution to ROS variability, suggesting that vehicle emission might be important driving factors of the PM-induced oxidative stress in the urban site.
اظهر المزيد [+] اقل [-]The GEOSS solution for enabling data interoperability and integrative research النص الكامل
2014
Nativi, Stefano | Mazzetti, Paolo | Craglia, Massimo | Pirrone, Nicola
Global sustainability research requires an integrative research effort underpinned by digital infrastructures (systems) able to harness data and heterogeneous information across disciplines. Digital data and information sharing across systems and applications is achieved by implementing interoperability: a property of a product or system to work with other products or systems, present or future. There are at least three main interoperability challenges a digital infrastructure must address: technological, semantic, and organizational. In recent years, important international programs and initiatives are focusing on such an ambitious objective. This manuscript presents and combines the studies and the experiences carried out by three relevant projects, focusing on the heavy metal domain: Global Mercury Observation System, Global Earth Observation System of Systems (GEOSS), and INSPIRE. This research work recognized a valuable interoperability service bus (i.e., a set of standards models, interfaces, and good practices) proposed to characterize the integrative research cyber-infrastructure of the heavy metal research community. In the paper, the GEOSS common infrastructure is discussed implementing a multidisciplinary and participatory research infrastructure, introducing a possible roadmap for the heavy metal pollution research community to join GEOSS as a new Group on Earth Observation community of practice and develop a research infrastructure for carrying out integrative research in its specific domain.
اظهر المزيد [+] اقل [-]New insight into molecular interaction of heavy metal pollutant—cadmium(II) with human serum albumin النص الكامل
2014
Liu, Yan | Chen, Mingmao | Jiang, Longguang | Song, Ling
Cadmium (Cd) is an extremely toxic metal commonly found as an environmental contaminant from industrial and agricultural sources, posing severe risks to human health. In this study, the binding mechanism of Cd(II)–human serum albumin (HSA) complex and the effect of Cd(II) on the conformational stability and structural state of HSA were comprehensively investigated through a series of efficient and appropriate methods. X-ray photoelectron spectroscopy accurately described the microenvironmental changes around protein C, N, and O atoms in the presence of Cd(II). Fluorescence results indicated that the probable mechanism of Cd(II)–HSA interaction is a static quenching process. Fourier transform infrared spectroscopy and dynamic light scattering showed Cd(II) complexation altered HSA conformation and the microenvironments of Trp and Tyr residues, accompanied by the size increases of HSA aggregates. This research will be helpful for understanding the toxic effects of Cd(II) on protein function in vivo. Figure The detailed binding mechanism between Cd(II) and HSA accompanied with the conformational analysis of HSA was comprehensively investigated at the molecular level
اظهر المزيد [+] اقل [-]Food sources of arsenic in pregnant Mediterranean women with high urine concentrations of this metalloid النص الكامل
2014
Fort, Marta | Grimalt, Joan O. | Casas, Maribel | Sunyer, Jordi
Seafood consumption provides a significant amount of arsenic, although in its organic, nontoxic forms. Mediterranean populations may incorporate high levels of this metalloid as a consequence of seafood consumption. In the present study, the significance of this input among pregnant women from a Mediterranean city (Sabadell, Catalonia, Spain) is assessed. Total urinary arsenic was analyzed in 489 pairs of urine samples, corresponding to the 12th and 32th weeks of pregnancy. Association of arsenic content with seafood and other dietary items were studied. Geometric mean concentrations were 34 and 37 μg/g creatinine during the first and third trimesters, respectively. The observed concentrations were similar to those reported in studies from other Mediterranean countries. The differences between both periods were not statistically significant. The only dietary factor significantly and positively associated with total urinary arsenic in both series of samples was seafood, particularly lean fish. Moreover, lean fish consumption during both periods was found to be the main determinant for differences in levels of arsenic between the first and third trimesters, which confirms the association between high levels of total urinary arsenic and seafood consumption.
اظهر المزيد [+] اقل [-]Phytostabilization potential of evening primrose (Oenothera glazioviana) for copper-contaminated sites النص الكامل
2014
Guo, Pan | Wang, Ting | Liu, Yanli | Xia, Yan | Wang, Guiping | Shen, Zhenguo | Chen, Yahua
A field investigation, field experiment, and hydroponic experiment were conducted to evaluate feasibility of using Oenothera glazioviana for phytostabilization of copper-contaminated soil. In semiarid mine tailings in Tongling, Anhui, China, O. glazioviana, a copper excluder, was a dominant species in the community, with a low bioaccumulation factor, the lowest copper translocation factor, and the lowest copper content in seed (8 mg kg⁻¹). When O. glazioviana was planted in copper-polluted farmland soil in Nanjing, Jiangsu, China, its growth and development improved and the level of γ-linolenic acid in seeds reached 17.1 %, compared with 8.73 % in mine tailings. A hydroponic study showed that O. glazioviana had high tolerance to copper, low upward transportation capacity of copper, and a high γ-linolenic acid content. Therefore, it has great potential for the phytostabilization of copper-contaminated soils and a high commercial value without risk to human health.
اظهر المزيد [+] اقل [-]Response surface modeling for optimization heterocatalytic Fenton oxidation of persistence organic pollution in high total dissolved solid containing wastewater النص الكامل
2014
Sekaran, G. | Karthikeyan, S. | Boopathy, R. | Maharaja, P. | Gupta, V. K. | Anandan, C.
The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N₂adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy,²⁹Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H₂O₂(4 mmol/L), FeSO₄[Symbol: see text]7H₂O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90 %, respectively.
اظهر المزيد [+] اقل [-]Review on physical and chemical characterizations of contaminated sediments from urban stormwater infiltration basins within the framework of the French observatory for urban hydrology (SOERE URBIS) النص الكامل
2014
El-Mufleh, Amelène | Béchet, Béatrice | Ruban, Véronique | Legret, Michel | Clozel, Blandine | Barraud, Sylvie | Gonzalez-Merchan, Carolina | Bedell, Jean-Philippe | Delolme, Cécile
Urban stormwater infiltration basins are designed to hold runoff from impervious surfaces and allow the settling of sediments and associated pollutants. However concerns have been expressed about the environmental impacts that may be exerted by the trapped pollutants on groundwater, soils and ecosystems. In this context, sediment characterization represents a key issue for local authorities in terms of management strategies. During the last two decades, several studies were launched including either physical or chemical characterization of stormwater sediments but without real synthesis of data and methods used. Consequently, there is an important need for reviewing the current experimental techniques devoted to the physico-chemical characterization of sediment. The review is based on the outcomes of two experimental sites for which long term monitoring and data collection have been done: the Cheviré basin (near Nantes) and the Django Reinhardt basin (near Lyon). The authors summarize the studies dealing with bulk properties, pollutant contents, their potential mobility and speciation. This paper aims at promoting the significant progresses that were made through a multidisciplinary approach involving multi-scaled and combined experimental techniques.
اظهر المزيد [+] اقل [-]Seasonal influences on PCB retention and biotransformation in fish النص الكامل
2014
James, Margaret O. | Kleinow, Kevin M.
There is extensive evidence that fish from waters with polychlorinated biphenyls (PCB)-contaminated sediments accumulate PCBs and related chemicals and that people who eat fish from contaminated waters have higher body burdens of PCBs and PCB metabolites than those who do not. PCBs and their metabolites are potentially toxic; thus, it is important to human health to understand the uptake, biotransformation, and elimination of PCBs in fish since these processes determine the extent of accumulation. The intestinal uptake of PCBs present in the diet of fish into fish tissues is a process that is influenced by the lipid composition of the diet. Biotransformation of PCBs in fish, as in mammals, facilitates elimination, although many PCB congeners are recalcitrant to biotransformation in fish and mammals. Sequential biotransformation of PCBs by cytochrome P450 and conjugation pathways is even less efficient in fish than in mammalian species, thus contributing to the retention of PCBs in fish tissues. A very important factor influencing overall PCB disposition in fish is water temperature. Seasonal changes in water temperature produce adaptive physiological and biochemical changes in fish. While uptake of PCBs from the diet is similar in fish acclimated to winter or summer temperatures, there is evidence that elimination of PCBs occurs much more slowly when the fish is acclimated at low temperatures than at warmer temperatures. Research to date suggests that the processes of elimination of PCBs are modulated by several factors in fish including seasonal changes in water temperature. Thus, the body burden of PCBs in fish from a contaminated location is likely to vary with season.
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