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Impact of elevated CO2 and elevated O3 on Beta vulgaris L.: Pigments, metabolites, antioxidants, growth and yield 全文
2013
Kumari, Sumita | Agrawal, Madhoolika | Tiwari, Supriya
The present study was conducted to assess morphological, biochemical and yield responses of palak (Beta vulgaris L. cv Allgreen) to ambient and elevated levels of CO2 and O3, alone and in combination. As compared to the plants grown in charcoal filtered air (ACO2), growth and yield of the plants increased under elevated CO2 (ECO2) and decreased under combination of ECO2 with elevated O3 (ECO2 + EO3), ambient O3 (ACO2 + AO3) and elevated O3 (EO3). Lipid peroxidation, ascorbic acid, catalase and glutathione reductase activities enhanced under all treatments and were highest in EO3. Foliar starch and organic carbon contents increased under ECO2 and ECO2 + EO3 and reduced under EO3 and ACO2 + AO3. Foliar N content declined in all treatments compared to ACO2 resulting in alteration of C/N ratio. This study concludes that ambient level of CO2 is not enough to counteract O3 impact, but elevated CO2 has potential to counteract the negative effects of future O3 level.
显示更多 [+] 显示较少 [-]Evaluating nutrient impacts in urban watersheds: Challenges and research opportunities 全文
2013
Carey, Richard O. | Hochmuth, George J. | Martinez, Christopher J. | Boyer, Treavor H. | Dukes, Michael D. | Toor, Gurpal S. | Cisar, J. L. (John L.)
This literature review focuses on the prevalence of nitrogen and phosphorus in urban environments and the complex relationships between land use and water quality. Extensive research in urban watersheds has broadened our knowledge about point and non-point pollutant sources, but the fate of nutrients is not completely understood. For example, it is not known how long-term nutrient cycling processes in turfgrass landscapes influence nitrogen retention rates or the relative atmospheric contribution to urban nitrogen exports. The effect of prolonged reclaimed water irrigation is also unknown. Stable isotopes have been used to trace pollutants, but distinguishing sources (e.g., fertilizers, wastewater, etc.) can be difficult. Identifying pollutant sources may aid our understanding of harmful algal blooms because the extent of the relationship between urban nutrient sources and algal blooms is unclear. Further research on the delivery and fate of nutrients within urban watersheds is needed to address manageable water quality impacts.
显示更多 [+] 显示较少 [-]An intermediate complexity dynamic model for predicting accumulation of atmospherically-deposited metals (Ni, Cu, Zn, Cd, Pb) in catchment soils: 1400 to present 全文
2013
The Intermediate Dynamic Model for Metals (IDMM) is a model for prediction of the pools of metals (Ni, Cu, Zn, Cd, Pb) in topsoils of catchments resulting from deposition of metals from the atmosphere. We used the model to simulate soil metal pools from 1400 onwards in ten UK catchments comprising semi-natural habitats, and compared the results with present day observations of soil metal pools. Generally the model performed well in simulating present day pools, and further improvements were made to simulations of Ni, Cu, Zn and Cd by adjusting the strength of metal adsorption to the soils. Some discrepancies between observation and prediction for Pb appeared to be due either to underestimation of cumulative deposition, or to overestimation of the metal pool under ‘pristine’, pre-industrial conditions. The IDMM provides a potential basis for large scale assessment of metal dynamics in topsoils.
显示更多 [+] 显示较少 [-]Quantitation of tetrabromobisphenol-A from dust sampled on consumer electronics by dispersed liquid-liquid microextraction 全文
2013
Tetrabromobisphenol-A (TBBPA) is a brominated flame retardant used worldwide. Despite its widespread use, there are few data concerning environmental concentrations of TBBPA. Thus, the objective of this work was to optimize an ultrasound-assisted dispersed liquid-liquid microextraction (DLLME) method to analyze swabbed surfaces of consumer electronics to determine TBBPA concentrations. Upon sample preparation with DLLME, TBBPA was derivatized with acetic anhydride and then analyzed by gas chromatography–mass spectrometry (GC/MS). Using a 13C12-TBBPA internal standard to improve precision and quantitation, a recovery study was performed. At concentrations of 250–1000 ng/mL, recoveries were 104–106%. Sample preparation with solid phase extraction had comparable recoveries, although overall, improved analyte recovery and precision were achieved with DLLME. In a small survey study, TBBPA concentrations in dust collected from 100 cm2 areas on electronic surfaces (monitor, microwave, refrigerator, and TV) were determined to range from less than the LOQ to 523 ng/mL.
显示更多 [+] 显示较少 [-]Effect of organic matter amendment, arsenic amendment and water management regime on rice grain arsenic species 全文
2013
Norton, Gareth J. | Adomako, Eureka E. | Deacon, Claire M. | Carey, Anne-Marie | Price, Adam H. | Meharg, Andrew A.
Arsenic accumulation in rice grain has been identified as a major problem in some regions of Asia. A study was conducted to investigate the effect of increased organic matter in the soil on the release of arsenic into soil pore water and accumulation of arsenic species within rice grain. It was observed that high concentrations of soil arsenic and organic matter caused a reduction in plant growth and delayed flowering time. Total grain arsenic accumulation was higher in the plants grown in high soil arsenic in combination with high organic matter, with an increase in the percentage of organic arsenic species observed. The results indicate that the application of organic matter should be done with caution in paddy soils which have high soil arsenic, as this may lead to an increase in accumulation of arsenic within rice grains. Results also confirm that flooding conditions substantially increase grain arsenic.
显示更多 [+] 显示较少 [-]Biomass burning in eastern Europe during spring 2006 caused high deposition of ammonium in northern Fennoscandia 全文
2013
Karlsson, Per Erik | Ferm, Martin | Tømmervik, Hans | Hole, Lars R. | Pihl Karlsson, Gunilla | Ruoho-Airola, Tuija | Aas, Wenche | Hellsten, Sofie | Akselsson, Cecilia | Mikkelsen, Teis Nørgaard | Nihlgård, Bengt
High air concentrations of ammonium were detected at low and high altitude sites in Sweden, Finland and Norway during the spring 2006, coinciding with polluted air from biomass burning in eastern Europe passing over central and northern Fennoscandia. Unusually high values for throughfall deposition of ammonium were detected at one low altitude site and several high altitude sites in north Sweden. The occurrence of the high ammonium in throughfall differed between the summer months 2006, most likely related to the timing of precipitation events. The ammonia dry deposition may have contributed to unusual visible injuries on the tree vegetation in northern Fennoscandia that occurred during 2006, in combination with high ozone concentrations. It is concluded that long-range transport of ammonium from large-scale biomass burning may contribute substantially to the nitrogen load at northern latitudes.
显示更多 [+] 显示较少 [-]Effects of copper on germination and reserve mobilization in Vicia sativa L. seeds 全文
2013
Muccifora, Simonetta | Bellani, Lorenza M.
The effects of different copper concentrations on percentage germination, increase in fresh weight and radicle growth of Vicia sativa L. seeds were studied. Physiological studies showed that the germination rate was not affected up to a concentration of 5 × 10−3 M, but already at 10−3 M the copper stopped root elongation. Structural and ultrastructural observations of embryo and cotyledon reserve mobilization showed that inhibition of radicle growth at 10−3 M Cu concentration cannot be ascribed to nutrient shortage but probably to an effect of copper on radicle cell division and elongation. In seeds treated with 5 × 10−3 M CuBr2, the copper completely inhibited cotyledon protein mobilization, so that embryo protein mobilization supported normal growth of the radicle up to 30 h after imbibition. The particular protein content of adjacent cotyledon cells is also discussed.
显示更多 [+] 显示较少 [-]Distribution of hydrocarbons released during the 2010 MC252 oil spill in deep offshore waters 全文
2013
Spier, Chelsea | Stringfellow, William T. | Hazen, Terry C. | Conrad, Mark
The explosion of the Deepwater Horizon oil platform on April 20th, 2010 resulted in the second largest oil spill in history. The distribution and chemical composition of hydrocarbons within a 45 km radius of the blowout was investigated. All available certified hydrocarbon data were acquired from NOAA and BP. The distribution of hydrocarbons was found to be dispersed over a wider area in subsurface waters than previously predicted or reported. A deepwater hydrocarbon plume predicted by models was verified and additional plumes were identified. Because the samples were not collected systematically, there is still some question about the presence and persistence of an 865 m depth plume predicted by models. Water soluble compounds were extracted from the rising oil in deepwater, and were found at potentially toxic levels outside of areas previously reported to contain hydrocarbons. Application of subsurface dispersants was found to increase hydrocarbon concentration in subsurface waters.
显示更多 [+] 显示较少 [-]Seasonal and spatial variation of trace elements and metals in quasi-ultrafine (PM0.25) particles in the Los Angeles metropolitan area and characterization of their sources 全文
2013
Saffari, Arian | Daher, Nancy | Shafer, Martin M. | Schauer, James J. | Sioutas, Constantinos
Year-long sampling campaign of quasi-ultrafine particles (PM0.25) was conducted at 10 distinct locations across the Los Angeles south coast air basin and concentrations of trace elements and metals were quantified at each site using high-resolution inductively coupled plasma sector field mass spectrometry. In order to characterize sources of trace elements and metals, principal component analysis (PCA) was applied to the dataset. The major sources were identified as road dust (influenced by vehicular emissions as well as re-suspended soil), vehicular abrasion, residual oil combustion, cadmium sources and metal plating. These sources altogether accounted for approximately 85% of the total variance of quasi-ultrafine elemental content. The concentrations of elements originating from source and urban locations generally displayed a decline as we proceeded from the coast to the inland. Occasional concentration peaks in the rural receptor sites were also observed, driven by the dominant westerly/southwesterly wind transporting the particles to the receptor areas.
显示更多 [+] 显示较少 [-]National inventory of alkylphenol ethoxylate compounds in U.S. sewage sludges and chemical fate in outdoor soil mesocosms 全文
2013
Venkatesan, Arjun K. | Halden, Rolf U.
We determined the first nationwide inventories of alkylphenol surfactants in U.S. sewage sludges (SS) using samples from the U.S. Environmental Protection Agency's 2001 national SS survey. Additionally, analysis of archived 3-year outdoor mesocosm samples served to determine chemical fates in SS-amended soil. Nonylphenol (NP) was the most abundant analyte (534 ± 192 mg/kg) in SS composites, followed by its mono- and di-ethoxylates (62.1 ± 28 and 59.5 ± 52 mg/kg, respectively). The mean annual load of NP and its ethoxylates in SS was estimated at 2408–7149 metric tonnes, of which 1204–4289 is applied on U.S. land. NP compounds showed observable loss from SS/soil mixtures (1:2), with mean half-lives ranging from 301 to 495 days. Surfactant levels in U.S. SS ten-times in excess of European regulations, substantial releases to U.S. soils, and prolonged half-lives found under field conditions, all argue for the U.S. to follow Europe's move from 20 years ago to regulate these chemicals.
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