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Structure and function of the bacterial communities during rhizoremediation of hexachlorobenzene in constructed wetlands Texto completo
2017
Zhang, Cuiping | Wang, Bei | Dai, Xiaoyan | Li, Shuying | Lu, Guangqiu | Zhou, Yuanqing
Vertical flow constructed wetlands (VF CWs) are considered to be effective for treating organic pollutants. The rhizosphere of macrophytes such as Phragmites sp., Typha sp. serves as an active and dynamic zone for the microbial degradation of organic pollutants. However, it is still not clear how soil bacterial communities respond to macrophytes and pollutants during the process. For this purpose, the seedlings of Phragmites australis and Typha angustifolia were planted respectively in the VF CWs added with HCB at a dose of 2 mg/kg. During 96 days of cultivation, we monitored hexachlorobenzene (HCB) removal efficiency by GC/MS and the structure of the rhizosphere bacterial communities in the different VF CWs by denaturing gradient gel electrophoresis (DGGE), and constructed bacterial clone library based on PCR-amplified 16S rRNA gene. As expected, the rhizosphere bacterial communities also remained insensitive to HCB exposure in the wetland soil. The diversity of these microbes presented two stages, from the varied up and down to equilibrium in the entire experimental period. Molecular analysis revealed that the phylum Firmicutes dominated over the bacterial communities. The genera that increased under HCB stress included the well-known HCB-degrading bacteria (Pseudomonas sp. and Alcaligenes sp.) and other common bacteria found in contaminated soil but with lesser known practical functions (Burkholderia sp., Lysinibacillus fusiformis, and Bacillus cereus). Furthermore, there was a certain variance in the relative abundances of the bacterial phyla and HCB removal efficiency among different VF CW treatments. The degradation of HCB in T. angustifolia microcosms was faster than that in P. australis and unvegetated wetlands, and the highest bacterial diversity and richness was found in the VF CWs comprising T. angustifolia.
Mostrar más [+] Menos [-]Monitoring of selected pharmaceuticals in surface waters of Croatia Texto completo
2017
Ivešić, Martina | Krivohlavek, Adela | Žuntar, Irena | Tolić, Sonja | Šikić, Sandra | Musić, Valerija | Pavlić, Ivan | Bursik, Andrea | Galić, Nives
Sulfonamides, macrolides, torasemide, fumagillin, and chloramphenicol were simultaneously analyzed in surface water samples by using solid-phase extraction (SPE) and reversed-phase (RP) liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS). In the pre-concentration and clean-up process, the pH value of samples and volume of the solvent for extraction of analytes from cartridge were optimized. Extraction recoveries were high with values in the range from 62 to 115%. Limits of quantification (LoQ) were in the range from 0.02 to 0.2 μg L⁻¹. Repeatability of the method was evaluated at LoQ and expressed as relative standard deviation (RSD). Calculated RSDs were low with values in the range from 2.4 to 14.5%. The method was successfully applied for analysis of surface water real samples. Samples were collected along the rivers in Croatia on four sampling sites in 2012 in Danube catchment areas, 19 sampling sites in Danube and Adriatic catchment areas in 2013, and another 19 places in 2014. Altogether, 20 target compounds were analyzed in 148 water samples and detected in 31 samples in range (0.1–5.3) μg L⁻¹ or in 20.1% of samples. The most frequent and highest concentrations were detected for macrolide antibiotics. This is the first attempt of such monitoring in surface waters in Croatia.
Mostrar más [+] Menos [-]Spatial variation and toxicity assessment for heavy metals in sediments of intertidal zone in a typical subtropical estuary (Min River) of China Texto completo
2017
Sun, Zhigao | Li, Jiabing | He, Tao | Ren, Peng | Zhu, He | Gao, Hui | Tian, Liping | Hu, Xingyun
Sediment samples were collected in five marshes (C1, Phragmites australis marsh; C2, P. australis and Cyperus malaccensis marsh; C3, C. malaccensis marsh; C4, Spartina alterniflora marsh; and C5, Cyperus compressus marsh) respectively along two typical transects (T1 and T2) extending from the vegetated marsh to the mudflat in a typical subtropical estuary (Min River) of China in July 2015 to investigate the spatial variation and toxicity of heavy metals (Pb, Cr, Cu, Zn, and Ni) in intertidal zone. Results showed that the concentrations of heavy metal in surface sediments of the two transects were in the order of Zn > Cr > Pb > Cu > Ni and slightly decreased from the land to the sea except for Pb and Zn. The levels of the five metals at C5 marsh were generally the lowest, while those of Pb, Cr, and Zn at C2 marsh were the highest. The vertical variations of Pb, Cr, and Zn concentrations in profiles differed among marshes or transects, and in most cases, there was no evidence of sediment organic matter (SOM) contributing to the sorption of significant amount of metals in sediments along the two transects, while grain composition was a primary factor controlling the spatial variations of metals. Both the vertical distributions of Cu and Ni levels among marshes or transects showed little fluctuation, which could be better explained by the effects of sulfur on the solubility and mobility of the two metals in profiles. Heavy metal levels in sediments of the Min River estuary were much higher compared with most estuaries in Asia, Europe, Africa, and South America. The sediments in intertidal zone of the Min River estuary were moderately polluted by the five metals, and particularly, Ni was identified as heavy metal of primary concern. Both Ni and Pb in sediments of the intertidal zone showed high potential toxicity and high contributions to the sum of the toxic units (ΣTUs). In future, the metal pollutions in intertidal zone of the Min River estuary might be more serious, and in the next step, there will be long-term potential consequences for endangered animals or migrant birds if measures are not taken to rehabilitate the sediments resulting from metal pollutions.
Mostrar más [+] Menos [-]Effects of epiphytic algae on biomass and physiology of Myriophyllum spicatum L. with the increase of nitrogen and phosphorus availability in the water body Texto completo
2017
Song, Yu-Zhi | Jin, Zhongda | Gao, Yong-Xia
The disappearance of submerged vascular macrophytes in shallow eutrophic lakes is a common phenomenon in the world. To explore the mechanism of the decline in submerged macrophyte abundance due to the growth of epiphytic algae along a nutrient gradient in eutrophic water, a 2 × 3 factorial experiment was performed over 4 weeks with the submerged macrophyte (Myriophyllum spicatum L.) by determining the plant’s biomass and some physiological indexes, such as chlorophyll (Chl) content, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity in the leaves of M. spicatum L. on days 7, 14, 21, and 28, which are based on three groups of nitrogen and phosphorus levels in the water body (N-P [mg L⁻¹]: NP1 0.5–0.05, NP2 2.5–0.25, NP3 4.5–0.45) and two levels of epiphytic algae (the epiphytic algae group and the control group). Epiphytic algal biomass was also assayed. The results indicated that epiphytic algal biomass remarkably enhanced in the course of the experiment with elevated levels of nitrogen and phosphorus in the water. Under the same level of nutrient condition, plants’ biomass accumulation and Chl content were higher in the control group than that in the epiphytic algae group, respectively, while MDA content and SOD activity in the former were lower than that in the latter. The influences of epiphytic algae on the biomass accumulation and Chl content and MDA content became greater and greater with elevated levels of nutrients. In general, in this experiment, water nutrients promoted the growth of both epiphytic algae and submerged plants, while the growth of epiphytic algae hindered submerged macrophytes’ growth by reducing Chl content and promoting peroxidation of membrane lipids in plants.
Mostrar más [+] Menos [-]Do rainfalls wash out anthropogenic airborne magnetic particulates? Texto completo
2017
Baatar, Amarjargal | Ha, Raegyung | Yu, Yongjae
We separated dust particles from the mesh-filtered sets of rainwaters collected on rainy days with daily precipitations exceeding 10 mm per day. A total of 136 rainwaters (or snow during the winter season) samples collected from February 2009 to February 2013 were analyzed. In particular, 33 out of 136 rainwaters were collected during or just after the Asian dust storm (ADS) events. Values of pH were relatively higher during warmer seasons. During ADS events, precipitations were alkaline, possibly due to abundant supply of alkaline minerals from the deserts source area to the precipitation. Compositional analysis on particulate matter (PM) indicated that Fe (and Al, K, and Mg) enriched the dusts collected during ADS, with respect to events than those without ADS. We found that ADS rainfall events are effective in selectively eliminating dust particles. However, high rainfall does not necessarily indicate more dilution of dusts. On microscopic examination, we observed natural soils, natural dust of pedogenesis or weathering origin, anthropogenic C–Fe-rich particles, and anthropogenic C-rich particles. Because of its small size, the stoichiometry of ADS-related, Fe-rich dust particles was inferred from the magnetic analysis. Presence of Verwey transition near 100–120 K and experimental determination of Curie points near 580 °C indicate that magnetic mineral responsible for the magnetic properties of ADS-related dusts was magnetite.
Mostrar más [+] Menos [-]Would environmental pollution affect home prices? An empirical study based on China’s key cities Texto completo
2017
Hao, Yu | Zheng, Shaoqing
With the development of China’s economy, the problem of environmental pollution has become increasingly more serious, affecting the sustained and healthy development of Chinese cities and the willingness of residents to invest in fixed assets. In this paper, a panel data set of 70 of China’s key cities from 2003 to 2014 is used to study the effect of environmental pollution on home prices in China’s key cities. In addition to the static panel data regression model, this paper uses the generalized method of moments (GMM) to control for the potential endogeneity and introduce the dynamics. To ensure the robustness of the research results, this paper uses four typical pollutants: per capita volume of SO₂ emissions, industrial soot (dust) emissions, industrial wastewater discharge, and industrial chemical oxygen demand discharge. The analysis shows that environmental pollution does have a negative impact on home prices, and the magnitude of this effect is dependent on the level of economic development. When GDP per capita increases, the size of the negative impact on home prices tends to reduce. Industrial soot (dust) has the greatest impact, and the impact of industrial wastewater is relatively small. It is also found that some other social and economic factors, including greening, public transport, citizen income, fiscal situation, loans, FDI, and population density, have positive effects on home prices, but the effect of employment on home prices is relatively weak.
Mostrar más [+] Menos [-]Nonlinear data assimilation for the regional modeling of maximum ozone values Texto completo
2017
Božnar, Marija Zlata | Grašič, Boštjan | Mlakar, Primož | Gradišar, Dejan | Kocijan, J.
We present a new method of data assimilation with the aim of correcting the forecast of the maximum values of ozone in regional photo-chemical models for areas over complex terrain using multilayer perceptron artificial neural networks. Up until now, these types of models have been used as a single model for one location when forecasting concentrations of air pollutants. We propose a method for constructing a more ambitious model: a single model, which can be used at several locations because the model is spatially transferable and is valid for the whole 2D domain. To achieve this goal, we introduce three novel ideas. The new method improves correlation at measurement station locations by 10% on average and improves by approximately 5% elsewhere.
Mostrar más [+] Menos [-]Toxicity, uptake, and accumulation of nano and bulk cerium oxide particles in Artemia salina Texto completo
2017
Sugantharaj David, Einstein Mariya David | Madurantakam Royam, Madhav | Rajamani Sekar, Suresh Kumar | Manivannan, Bhuvaneshwari | Jalaja Soman, Swathy | Mukherjee, Amitava | Natarajan, Chandrasekaran
Although the toxicological impact of metal oxide nanoparticles has been studied for the last few decades on aquatic organisms, the exact mechanism of action is still unclear. The fate, behavior, and biological activity of nanoparticles are dependent on physicochemical factors like size, shape, surface area, and stability in the medium. This study deals with the effect of nano and bulk CeO₂ particles on marine microcrustacean, Artemia salina. The primary size was found to be 15 ± 3.5 and 582 ± 50 nm for nano and bulk CeO₂ (TEM), respectively. The colloidal stability and sedimentation assays showed rapid aggregation of bulk particles in seawater. Both the sizes of CeO₂ particles inhibited the hatching rate of brine shrimp cyst. Nano CeO₂ was found to be more toxic to A. salina (48 h LC₅₀ 38.0 mg/L) when compared to bulk CeO₂ (48 h LC₅₀ 92.2 mg/L). Nano CeO₂-treated A. salina showed higher oxidative stress (ROS) than those treated with the bulk form. The reduction in the antioxidant activity indicated an increase in oxidative stress in the cells. Higher acetylcholinesterase activity (AChE) was observed upon exposure to nano and bulk CeO₂ particles. The uptake and accumulation of CeO₂ particles were increased with respect to the concentration and particle size. Thus, the above results revealed that nano CeO₂ was more lethal to A. salina as compared to bulk particles.
Mostrar más [+] Menos [-]Human exposure to perfluoroalkyl substances near a fluorochemical industrial park in China Texto completo
2017
Bao, Jia | Liu, Li | Wang, Xin | Jin, Yi-He | Dong, Guang-Hui
Severe perfluoroalkyl substance (PFAS) contaminations have been observed in both surface water and groundwater in the vicinity of Fuxin, China, over the past years, attributing to the fast-growing fluorochemical industries locally. However, little is known about the overall daily intake of PFAS contaminations by Fuxin residents recently. In the present study, ten target PFAS analytes in the blood serum samples collected from 100 non-occupationally exposed healthy residents in Fuxin, with an average age of 47.6 years, together with 14 drinking water samples obtained from the public water system (PWS) of Fuxin were analyzed via high-performance liquid chromotography–tandem mass spectrometry (HPLC–MS/MS). As the dominant PFAS contaminant, the serum concentrations of perfluorooctanoic acid (PFOA) in Fuxin residents ranged between <0.05 and 160 ng/mL, with a median concentration of 9.4 ng/mL, which was higher than those reported previously for Fuxin and other areas worldwide. In drinking water samples, PFOA had a median value of 8.5 ng/L, ranging from 7.7 to 8.8 ng/L. Based upon the simplified one-compartment pharmacokinetic model, the total daily intake of PFOA for individuals residing in Fuxin ranged from 0.30 to 1.76 ng/kg bw/day, with a median of 0.79 ng/kg bw/day; furthermore, daily consumption of drinking water from the PWS in Fuxin appeared to contribute 35% of overall PFOA burden in local residents, which was approximately 3-fold higher compared to that estimated for Fuxin residents in 2009.
Mostrar más [+] Menos [-]Iron encapsulated in 3D N-doped carbon nanotube/porous carbon hybrid from waste biomass for enhanced oxidative activity Texto completo
2017
Yao, Yunjin | Zhang, Jie | Wu, Guodong | Wang, Shaobin | Hu, Yi | Su, Cong | Xu, Tongwen
Novel iron encapsulated in nitrogen-doped carbon nanotubes (CNTs) supported on porous carbon (Fe@N-C) 3D structured materials for degrading organic pollutants were fabricated from a renewable, low-cost biomass, melamine, and iron salt as the precursors. SEM and TEM micrographs show that iron encapsulated bamboo shaped CNTs are vertically standing on carbon sheets, and thus, a 3D hybrid was formed. The catalytic activities of the prepared samples were thoroughly evaluated by activation of peroxymonosulfate for catalytic oxidation of Orange II solutions. The influences of some reaction conditions (pH, temperature, and concentrations of reactants, peroxymonosulfate, and dye) were extensively evaluated. It was revealed that the adsorption could enrich the pollutant which was then rapidly degraded by the catalytically generated radicals, accelerating the continuous adsorption of residual pollutant. Remarkable carbon structure, introduction of CNTs, and N/Fe doping result in promoted adsorption capability and catalytic performances. Due to the simple synthetic process and cheap carbon precursor, Fe@N-C 3D hybrid can be easily scaled up and promote the development of Fenton-like catalysts.
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