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Resultados 1291-1300 de 1,506
Seed bank persistence of genetically modified canola in California
2012
Munier, Douglas J. | Brittan, Kent L. | Lanini, W Thomas
INTRODUCTION: Canola, which is genetically modified (GM) for tolerance to glyphosate, has the potential to become established as a new glyphosate resistant weed, thus reducing the effectiveness of glyphosate. METHODS: Volunteer from dormant canola seeds produced thousands of plants per hectare in the fourth year (2011) following a 2007 crop harvest. This occurred with no additional canola seed production since the 2007 harvest. RESULTS: Volunteer plants following harvests of annual crops are typically only a problem for the first year after harvest. In California, glyphosate is the core herbicide on over a million hectares of high value row, tree, and vine crops and new glyphosate resistant weeds reduce the effectiveness of glyphosate. CONCLUSIONS: The combination of dormant seed and herbicide resistance makes GM glyphosate-resistant canola a new and difficult California weed which was first observed in the winter of 2009.
Mostrar más [+] Menos [-]Assessing the removal of pharmaceuticals and personal care products in a full-scale activated sludge plant
2012
Salgado, R. | Marques, R. | Noronha, J. P. | Carvalho, G. | Oehmen, A. | Reis, M. A. M.
PURPOSE: This study aimed to investigate the removal mechanisms of pharmaceutical active compounds (PhACs) and musks in a wastewater treatment plant (WWTP). Biological removal and adsorption in the activated sludge tank as well as the effect of UV radiation used for disinfection purposes were considered when performing a mass balance on the WWTP throughout a 2-week sampling campaign. METHODS: Solid-phase extraction (SPE) was carried out to analyse the PhACs in the influent and effluent samples. Ultrasonic solvent extraction was used before SPE for PhACs analysis in sludge samples. PhAC extracts were analysed by LC-MS. Solid-phase microextraction of liquid and sludge samples was used for the analysis of musks, which were detected by GC-MS. The fluxes of the most abundant compounds (13 PhACs and 5 musks) out of 79 compounds studied were used to perform the mass balance on the WWTP. RESULTS: Results show that incomplete removal of diclofenac, the compound that was found in the highest abundance, was observed via biodegradation and adsorption, and that UV photolysis was the main removal mechanism for this compound. The effect of adsorption to the secondary sludge was often negligible for the PhACs, with the exceptions of diclofenac, etofenamate, hydroxyzine and indapamide. However, the musks showed a high level of adsorption to the sludge. UV radiation had an important role in reducing the concentration of some of the target compounds (e.g. diclofenac, ibuprofen, clorazepate, indapamide, enalapril and atenolol) not removed in the activated sludge tank. CONCLUSIONS: The main removal mechanism of PhACs and musks studied in the WWTP was most often biological (45%), followed by adsorption (33%) and by UV radiation (22%). In the majority of the cases, the WWTP achieved >75% removal of the most detected PhACs and musks, with the exception of diclofenac.
Mostrar más [+] Menos [-]Daily, seasonal and monthly variations in ozone levels recorded at the Turia river basin in Valencia (Eastern Spain)
2012
Castell-Balaguer, Nuria | Téllez, Laura | Mantilla, Enrique
INTRODUCTION: The Turia river basin, located in the east of the Iberian Peninsula, drains into the Mediterranean Sea near the city of Valencia (population, 814,208). The predominance of sea-breeze fluxes favours the inland transport of pollutants from the city up the basin where ozone concentrations exceeding the threshold for protection of human health are systematically recorded during the summer months. METHODS: This work analyses the variability in ozone levels by examining their spatial and temporal distribution in a Mediterranean river basin downwind from a city within the period 2005–2008. Orographic determinants and atmospheric fluxes induce strong variations in ozone measurements, even on relatively close locations. CONCLUSIONS: Results show a different behaviour of the monthly means and the daily cycles depending on the season of the year and the measuring environment, with summer/winter ratios ranging from 2.4 in cities to 1.6 inland, and mean values always higher in the interior of the basin. Daily cycles show significant summer/winter differences related to the predominant situations of anticyclonic stability in winter, which limit ventilation, and the predominant breeze circulations in summer. Results also show a “weekend effect” at urban and medium-distance stations. At the most inland station, the weekend/weekday behaviour differs according to the season of the year; weekend ozone levels are higher in spring, autumn and winter, and lower in summer, coinciding with the predominance of local wind cycles that favour air mass penetration inland from the coast.
Mostrar más [+] Menos [-]Enhancement of natural radioactivity in fertilized soil of Faisalabad, Pakistan
2012
Ak̲h̲tar, Nasīm | Sabiha-Javied, | Tufail, M.
BACKGROUND, GOAL, AND SCOPE: Natural radioactivity in phosphate rock (PR) is transferred to phosphate fertilizer (PF) during the manufacturing process of the PF. The continuous addition of the PF to the cultivated soil accumulates the radionuclides in the land and increases the level of radioactivity in the soil. The purpose of the present study was to investigate the enhanced level of accumulated radioactivity due to the continuous addition of the PF in the farmlands of Nuclear Institute of Agriculture and Biology (NIAB) at Faisalabad in Pakistan. The selected study area consisted of the highly fertilized farmlands and an unfertilized barren land of the NIAB. INTRODUCTION: The understudy area is very fertile for the growth of various types of crops; therefore, four agricultural research institutes have been established at Faisalabad and NIAB is one of those. The NIAB has developed various research farmlands at different places in Pakistan. The crop yield has been increased by adding various fertilizers in the farmlands. The addition of the PF accompanied with the radionuclides enhances radioactivity in the fields. Human being is exposed directly or indirectly to this radiological hazard. A prolong exposure may become a cause of health risk. MATERIALS AND METHODS: The area of study consisted of three types of lands: the land under cultivation for the last 40 and 30 years called Site 1 and Site 2, respectively, and the barren land was called Site 3. A total of 75 soil samples were collected within the crop rooting zone (up to 25 cm deep) of the soil of the NIAB farms. The samples were dried, pulverized to powder, sealed in plastic containers, and stored to achieve equilibrium between 226Ra and 222Rn. Activity concentrations of the radionuclides 238U (226Ra), 232Th, and 40K in soil samples were determined by using a high resolution gamma ray spectrometry system, consisting of an high purity germanium detector coupled through a spectroscopy amplifier with a PC based MCA installed with Geni-2000 software. RESULTS: The measured activity concentration levels of 40K were 662 ± 15, 615 ± 17, and 458 ± 20 Bq kg−1, 226Ra were 48 ± 6, 43 ± 5, and 26 ± 4 Bq kg−1, and that of 232Th were 39 ± 5, 37 ± 5, 35 ± 5 Bq kg−1, respectively, in the soil of the Sites 1, 2, and 3. Gamma dose rate 1 m above the soil surface was 55, 51, and 40 nGy h−1 from Sites 1, 2, and 3, respectively. External dose rates in the rooms constructed of the bricks made of the soil from Sites 1, 2, and 3 were 161, 149, and 114 nGyh−1, respectively. DISCUSSIONS: Activity concentration values of 40K and 226Ra in the soil of Sites 1 and 2 were higher than that in the soil of Site 3. The relative rise of 40K was 43 % and 34 % and that of 226Ra was 85 % and 65 % respectively in these sites. Activity concentrations of 232Th in all these sites were in the background range. Gamma dose rate 1 m above soil surface of Sites 1 and 2 was 40 % and 30 % respectively higher than that from the soil of Site 3. The rise in activity of 40K and 226Ra and gamma dose from the Site 1 was greater than that from the Site 2. The least activity and dose were observed from the Site 3. Gamma dose in the dwellings made of fertilized soil bricks of Site 1 and Site 2 were respectively calculated to be 41 % and 32 % higher than that in the abodes made of unfertilized soil bricks of Site 3. CONCLUSIONS: Activity concentrations of 226Ra and 40K were observed to be enhanced in the fertilized farmlands of the NIAB. Outdoor and indoor gamma dose as radiological hazard were found to be increasing with the continuous addition of PF in the understudy farmlands. RECOMMENDATIONS: It is recommended that naturally occurring radioactive metal should be removed during the process of manufacturing of the PF from the PR. PROSPECTIVE: The rise in radioactivity in the farmlands due to the addition of the PF can be a source of direct or indirect exposure to radiation that may enhance cancer risk of the exposed individuals.
Mostrar más [+] Menos [-]Airborne lead levels in the Korean peninsula: characterization of temporal and spatial patterns and cancer risk analysis
2012
Mutlu, Atilla | Lee, Byeong-Kyu
INTRODUCTION: This study collected long-term airborne lead concentrations in the Korean peninsula and analyzed their temporal, spatial, and cancer risk characterization. METHODS: Approximately, 12,000 airborne samples of total suspended particulate (TSP) were collected from 30 ambient air monitoring stations in inland (Daegu, Daejeon, Gwangju, and Seoul) cities and portal cities (Incheon, Busan, and Ulsan) over a period of 7 years (2004–2010). High volume air samplers were employed to collect daily TSP samples during the second week of the consecutive months throughout the entire study period. The concentrations of Pb extracted from the TSP samples were analyzed using either inductively coupled plasma-atomic emission or flame atomic absorption spectrometry. RESULTS: The long-term high mean Pb concentrations were observed in the port cities including Incheon (88 ± 18 ng/m3), Ulsan (61 ± 7 ng/m3), and Busan (58 ± 6 ng/m3). In the temporal analysis, seasonal mean Pb levels were relatively higher in winter and spring than those in summer and fall. In the spatial analysis, the mean Pb levels in spring, winter, and fall from Incheon, which showed the highest seasonal concentrations except summer, were 110 ± 19, 101 ± 18, and 76 ± 23 ng/m3, respectively. In summer, the highest seasonal mean Pb level was observed in the largest industrial city and the second port city, Ulsan (78 ± 15 ng/m3), followed by Incheon (65 ± 13 ng/m3). CONCLUSION: The estimated excess cancer risk analysis showed that inhalation of Pb could result in cancer for one or two persons per million of population in the Korean peninsula.
Mostrar más [+] Menos [-]Copper chitosan nanocomposite: synthesis, characterization, and application in removal of organophosphorous pesticide from agricultural runoff
2012
Jaiswal, Meha | Chauhan, Divya | Sankararamakrishnan, Nalini
PURPOSE: Removal of malathion from agricultural runoff was studied using novel copper-coated chitosan nanocomposite (CuCH)—a biopolymeric waste obtained from marine industry. METHODS: Synthesis and characterization of the adsorbent using different spectral techniques like Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer, Emmett, and Teller surface analyzer have been carried out. Equilibrium studies have been carried out to optimize the dose rate, pH, and the reaction time. Parathion and methyl parathion removal were also evaluated by CuCH in the batch mode. Using gas chromatography–mass spectrometry (GC–MS) and FTIR studies suitable mechanism for adsorption has been suggested. RESULTS: The particle size of the adsorbent ranged from 700 to 750 nm. The surface area was found to be 20 m2 g-1 with a pore volume of 0.11 cc g-1. The maximum adsorption capacity of malathion by CuCH was found to be 322.6 ± 3.5 mg g-1 at an optimum pH of 2.0. Presence of copper ions enhanced the adsorption capacity of the adsorbent. The reaction was found to follow pseudo second-order kinetics with a rate constant of 0.53 g mg-1 min-1. Evidence from FTIR indicated that copper ions form a dithionate complex with malathion during the adsorption stage. The adsorbent was found to remove malathion completely from spiked concentration of 2 mg l-1 in the agricultural run-off samples. It was also found that CuCH removed other organophospurous pesticides like methyl parathion and parathion under prevailing conditions. CONCLUSIONS: The results indicated that CuCH could be applied for the removal of organophosphorous pesticides.
Mostrar más [+] Menos [-]Large-scale spatial pollution patterns around the North Sea indicated by coastal bird eggs within an EcoQO programme
2012
Dittmann, Tobias | Becker, Peter H. | Bakker, Joop | Bignert, Anders | Nyberg, Elisabeth | Pereira, M Glória | Pijanowska, Ursula | Shore, Richard F. | Stienen, Eric | Toft, Geir Olav | Marencic, Harald
To categorize the marine environmental health status, the Oslo and Paris commissions have recently formulated Ecological Quality Objectives (EcoQOs) for many ecological features including the contamination of coastal bird eggs with mercury and organochlorines. In this study, we describe spatial and temporal patterns of egg contamination around the North Sea and compared them to the EcoQOs. Concentrations of mercury, polychlorinated biphenyl (ΣPCB) congeners, dichlorodiphenyltrichloroethane (ΣDDT) and derivatives, hexachlorobenzene (HCB) and hexachlorocyclohexane (ΣHCH) isomers were analysed in two tern species (Sterna hirundo and Sterna paradisaea) and Oystercatcher (Haematopus ostralegus) eggs collected between 2008 and 2010 in a total of 21 sites in seven countries surrounding the North Sea. Hg, ΣPCB and HCB were highest in the southern sites, while ΣDDT and ΣHCH concentrations were greatest in eggs from the western North Sea and the Elbe estuary. There were rarely any consistent decreases over time for any compounds. In the terns, Hg, HCB and ΣHCH increased at most sites, ΣPCB and ΣDDT in Sweden and Norway. In the Oystercatcher, HCB and ΣHCH increased at more than the half of the sites, ΣPCB, ΣDDT and Hg at several German sites. In the terns, Hg, ΣPCB and ΣDDT exceeded the EcoQO in all, HCB in most years and sites. At most sites, ΣHCH fulfilled the EcoQO in some study years. In the Oystercatcher, Hg, ΣPCB and ΣDDT exceeded the EcoQO in all or most years and sites. HCB and ΣHCH fulfilled the EcoQO in some or all years at most sites. The EcoQO was exceeded most frequently in estuaries. We conclude that EcoQOs are suitable for drawing contamination patterns of the coastal North Sea in an easily understandable manner, offering the opportunity to harmonize the EcoQOs with coordinated environmental monitoring programmes.
Mostrar más [+] Menos [-]Oxidative transformation of carbamazepine by manganese oxides
2012
He, Yan | Xu, Jian | Zhang, Yuan | Guo, Changsheng | Li, Lei | Wang, Yuqiu
This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (δ-MnO2) as well as impact of variables including initial MnO2 loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (δ-MnO2) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50 mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0 mg/L of carbamazepine and 130.5 mg/L of MnO2. Effects of initial MnO2 loading (0–130.5 mg/L), pH (2.72–8.58) and 0.01 M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5 min, and approximately 95 % of carbamazepine was eliminated within 60 min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO2 loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn2+ > Fe3+ > Ca2+ ≈ Mg2+. Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by δ-MnO2, and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO2 be a potential alternative to solve carbamazepine pollution.
Mostrar más [+] Menos [-]Co-remediation of cadmium-polluted soil using stainless steel slag and ammonium humate
2012
Zhuo, Lin | Li, Hua | Cheng, Fangqin | Shi, Yonglin | Zhang, Qiuhua | Shi, Weiyu
INTRODUCTION AND METHODS: This study investigated the remediation of cadmium-polluted soil using a combination of stainless steel slag and ammonium humate. These remedial agents were added to an artificially polluted garden soil to inhabit cadmium toxicity in soil by changing the physical and chemical properties of soil in a pot experiment. RESULTS AND CONCLUSIONS: The results showed that the co-application of ammonium humate and stainless steel slag significantly decreased the total and available soil cadmium concentrations, with maximum decreases of 16.30% and 58.04%, respectively. The co-application of an adequate dose of these remedial agents can significantly increase soil pH. The soil organic matter and cation exchange capacity, as well as the amount of soil aggregates, were also significantly increased by the addition ammonium humate, but not stainless steel slag.
Mostrar más [+] Menos [-]Degradation of 2,4-D in soils by Fe3O 4 nanoparticles combined with stimulating indigenous microbes
2012
Fang, Guodong | Si, Youbin | Tian, Chao | Zhang, Gangya | Zhou, Dongmei
PURPOSE: Degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in soils by Fe3O4 nanoparticles combined with soil indigenous microbes was investigated, and the effects of Fe3O4 nanoparticles on soil microbial populations and enzyme activities were also studied. METHODS: The soils contaminated with 2,4-D were treated with Fe3O4 nanoparticles. The microbial populations and enzyme activities were analyzed by dilution plate method and chemical assay, respectively, and the concentration of 2,4-D in soil was determined by high-performance liquid chromatography (HPLC). RESULTS: The results indicated that Fe3O4 nanoparticles combined with soil indigenous microbes led to a higher degradation efficiency of 2,4-D than the treatments with Fe3O4 nanoparticles or indigenous microbes alone. The degradation of 2,4-D in soils followed the pseudo first-order kinetic. The half-lives of 2,4-D degradation (DT50) of the combined treatments were 0.9, 1.9 and 3.1 days in a Red soil, Vertisol and Alfisol, respectively, which implied that the DT50 of the combination treatments were significantly shorter than that of the treatments Fe3O4 nanoparticles or indigenous microbes alone. The effects of Fe3O4 nanoparticles on soil microbial populations and enzyme activities were also investigated and compared with the α-Fe2O3 nanoparticles. The results suggested that the α-Fe2O3 nanoparticles had only comparatively small effects on degradation of 2,4-D in soils, while the Fe3O4 nanoparticles not only degraded 2,4-D in soils but also increased the soil microbial populations and enzyme activities; the maximum increase in enzyme activities were 67.8% (amylase), 53.8% (acid phosphatase), 26.5% (catalase) and 38.0% (urease), compared with the untreated soil. Moreover, the introduction of Fe3O4 nanoparticles at the different dosage resulted in a variable degradation efficiency of 2,4-D in soil. CONCLUSION: The method of combining Fe3O4 nanoparticles with indigenous soil microbes may offer great benefits for the application of nanotechnology in remediation of herbicide contaminated soil.
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