خيارات البحث
النتائج 1571 - 1580 من 1,908
Observation of carbonaceous aerosols during 2006–2009 in Nyainqêntanglha Mountains and the implications for glaciers
2013
Zhao, Shuyu | Ming, Jing | Sun, Junying | Xiao, Cunde
Atmospheric carbonaceous aerosols were sampled discontinuously from July 2006 to December 2009 at Nam Co Comprehensive Observation and Research Station (NCOS) in the central Tibetan Plateau (TP). The mean daily concentration of carbonaceous aerosols increased from 268 to 330 ng m(-3), and pollution episodes could significantly increase the mean level of carbonaceous aerosols in the total mass concentration. Organic carbon was the main component of carbonaceous aerosols at NCOS, and black carbon (BC) accounted for 5.8 %. Seven-day air masses backward trajectories calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory model and the aerosol optical depth distribution in the TP and South Asia both suggested that atmospheric pollutants emitted from Northern India and South Asia could penetrate into central TP by southwest winds. Due to the seasonal variations of emission sources and regional atmospheric conditions, calculated BC deposition flux in the nonmonsoon season was higher than that in the monsoon season. Increased BC concentration in snowpack in winter from 2007 to 2009 indicated that the atmospheric environment in central TP became more polluted and the influences from human activities have strengthened. Pollution episodes could significantly increase BC concentrations in the snowpack on a seasonal scale, which would furthermore affect the surface albedo.
اظهر المزيد [+] اقل [-]Use of EO-1 Advanced Land Imager (ALI) multispectral image data and real-time field sampling for water quality mapping in the Hirfanlı Dam Lake, Turkey
2013
Kavurmacı, Murat | Ekercin, Semih | Altaş, Levent | Kurmaç, Yakup
This paper focuses on the evaluation of water quality variations in Hirfanlı Water Reservoir, which is one of the most important water resources in Turkey, through EO-1 (Earth Observing-1) Advanced Land Imager (ALI) multispectral data and real-time field sampling. The study was materialized in 20 different sampling points during the overpass of the EO-1 ALI sensor over the study area. A multi-linear regression technique was used to explore the relationships between radiometrically corrected EO-1 ALI image data and water quality parameters: chlorophyll a, turbidity, and suspended solids. The retrieved and verified results show that the measured and estimated values of water quality parameters are in good agreement (R ² > 0.93). The resulting thematic maps derived from EO-1 multispectral data for chlorophyll a, turbidity, and suspended solids show the spatial distribution of the water quality parameters. The results indicate that the reservoir has average nutrient values. Furthermore, chlorophyll a, turbidity, and suspended solids values increased at the upstream reservoir and shallow coast of the Hirfanlı Water Reservoir.
اظهر المزيد [+] اقل [-]Contamination of different portions of raw and boiled specimens of Norway lobster by mercury and selenium
2013
Perugini, Monia | Visciano, Pierina | Manera, Maurizio | Abete, Maria Cesarina | Gavinelli, Stefania | Amorena, Michele
The aim of this study was to evaluate mercury and selenium distribution in different portions (exoskeleton, white meat and brown meat) of Norway lobster (Nephrops norvegicus). Some samples were also analysed as whole specimens. The same portions were also examined after boiling, in order to observe if this cooking practice could affect mercury and selenium concentrations. The highest mercury concentrations were detected in white meat, exceeding in all cases the maximum levels established by European legislation. The brown meat reported the highest selenium concentrations. In all boiled samples, mercury levels showed a statistically significant increase compared to raw portions. On the contrary, selenium concentrations detected in boiled samples of white meat, brown meat and whole specimen showed a statistically significant decrease compared to the corresponding raw samples. These results indicate that boiling modifies mercury and selenium concentrations. The high mercury levels detected represent a possible risk for consumers, and the publication and diffusion of specific advisories concerning seafood consumption is recommended.
اظهر المزيد [+] اقل [-]Uptake and translocation of organophosphates and other emerging contaminants in food and forage crops
2013
Eggen, Trine | Heimstad, Eldbjørg S. | Stuanes, A. O. (Arne O.) | Norli, Hans Ragnar
Emerging contaminants in wastewater and sewage sludge spread on agricultural soil can be transferred to the human food web directly by uptake into food crops or indirectly following uptake into forage crops. This study determined uptake and translocation of the organophosphates tris(1-chloro-2-propyl) phosphate (TCPP) (log Kₒw2.59), triethyl-chloro-phosphate (TCEP) (log Kₒw1.44), tributyl phosphate (TBP) (log Kₒw4.0), the insect repellent N,N-diethyl toluamide (DEET) (log Kₒw2.18) and the plasticiser N-butyl benzenesulfonamide (NBBS) (log Kₒw2.31) in barley, wheat, oilseed rape, meadow fescue and four cultivars of carrot. All species were grown in pots of agricultural soil, freshly amended contaminants in the range of 0.6–1.0 mg/kg dry weight, in the greenhouse. The bioconcentration factors for root (RCF), leaf (LCF) and seed (SCF) were calculated as plant concentration in root, leaf or seed over measured initial soil concentration, both in dry weight. The chlorinated flame retardants (TCEP and TCPP) displayed the highest bioconcentration factors for leaf and seed but did not show the same pattern for all crop species tested. For TCEP, which has been phased out due to toxicity but is still found in sewage sludge and wastewater, LCF was 3.9 in meadow fescue and 42.3 in carrot. For TCPP, which has replaced TCEP in many products and also occurs in higher residual levels in sewage sludge and wastewater, LCF was high for meadow fescue and carrot (25.9 and 17.5, respectively). For the four cultivars of carrot tested, the RCF range for TCPP and TCEP was 10–20 and 1.7–4.6, respectively. TCPP was detected in all three types of seeds tested (SCF, 0.015–0.110). Despite that DEET and NBBS have log Kₒwin same range as TCPP and TCEP, generally lower bioconcentration factors were measured. Based on the high translocation of TCPP and TCEP to leaves, especially TCPP, into meadow fescue (a forage crop for livestock animals), ongoing risk assessments should be conducted to investigate the potential effects of these compounds in the food web.
اظهر المزيد [+] اقل [-]Remote estimation of phycocyanin (PC) for inland waters coupled with YSI PC fluorescence probe
2013
Song, Kaishan | Li, Lin | Tedesco, Lenore | Clercin, Nicole | Hall, Bob | Li, Shuai | Shi, Kun | Liu, Dawei | Sun, Ying
Nuisance cyanobacterial blooms degrade water resources through accelerated eutrophication, odor generation, and production of toxins that cause adverse effects on human health. Quick and effective methods for detecting cyanobacterial abundance in drinking water supplies are urgently needed to compliment conventional laboratory methods, which are costly and time consuming. Hyperspectral remote sensing can be an effective approach for rapid assessment of cyanobacterial blooms. Samples (n = 250) were collected from five drinking water sources in central Indiana (CIN), USA, and South Australia (SA), which experience nuisance cyanobacterial blooms. In situ hyperspectral data were used to develop models by relating spectral signal with handheld fluorescence probe (YSI 6600 XLM-SV) measured phycocyanin (PC in cell/ml), a proxy pigment unique for indicating the presence of cyanobacteria. Three-band model (TBM), which is effective for chlorophyll-a estimates, was tuned to quantify cyanobacteria coupled with the PC probe measured cyanobacteria. As a comparison, two band model proposed by Simis et al. (Limnol Oceanogr, 50(11): 237–245, 2005; denoted as SM05) was paralleled to evaluate TBM model performance. Our observation revealed a high correlation between measured and estimated PC for SA dataset (R ² = 0.96; range: 534–20,200 cell/ml) and CIN dataset (R ² = 0.88; range: 1,300–44,500 cell/ml). The potential of this modeling approach for imagery data were assessed by simulated ESA/Centinel3/OLCI spectra, which also resulted in satisfactory performance with the TBM for both SA dataset (RMSE % = 26.12) and CIN dataset (RMSE % = 34.49). Close relationship between probe-measured PC and laboratory measured cyanobacteria biovolume was observed (R ² = 0.93, p < 0.0001) for the CIN dataset, indicating a stable performance for PC probe. Based on our observation, field spectroscopic measurement coupled with PC probe measurements can provide quantitative cyanobacterial bloom information from both relatively static and flowing inland waters. Hence, it has promising implications for water resource managers to obtain information for early warning detection of cyanobacterial blooms through the close association between probe measured PC values and cyanobacterial biovolume via remote sensing modeling.
اظهر المزيد [+] اقل [-]Tracer-based source apportionment of polycyclic aromatic hydrocarbons in PM₂.₅ in Guangzhou, southern China, using positive matrix factorization (PMF)
2013
Gao, Bo | Guo, Hai | Wang, Xin-Ming | Zhao, Xiu-Ying | Ling, Zhen-Hao | Zhang, Zhou | Liu, Teng-Yu
From 28 November to 23 December 2009, 24-h PM₂.₅ samples were collected simultaneously at six sites in Guangzhou. Concentrations of 18 polycyclic aromatic hydrocarbons (PAHs) together with certain molecular tracers for vehicular emissions (i.e., hopanes and elemental carbon), coal combustion (i.e., picene), and biomass burning (i.e., levoglucosan) were determined. Positive matrix factorization (PMF) receptor model combined with tracer data was applied to explore the source contributions to PAHs. Three sources were identified by both inspecting the dominant tracer(s) in each factor and comparing source profiles derived from PMF with determined profiles in Guangzhou or in the Pearl River Delta region. The three sources identified were vehicular emissions (VE), biomass burning (BB), and coal combustion (CC), accounting for 11 ± 2 %, 31 ± 4 %, and 58 ± 4 % of the total PAHs, respectively. CC replaced VE to become the most important source of PAHs in Guangzhou, reflecting the effective control of VE in recent years. The three sources had different contributions to PAHs with different ring sizes, with higher BB contributions (75 ± 3 %) to four-ring PAHs such as pyrene and higher CC contributions (57 ± 4 %) to six-ring PAHs such as benzo[ghi]perylene. Temporal variations of VE and CC contributions were probably caused by the change of weather conditions, while temporal variations of BB contributions were additionally influenced by the fluctuation of BB emissions. Source contributions also showed some spatial variations, probably due to the source emission variations near the sampling sites.
اظهر المزيد [+] اقل [-]DNA integrity of onion root cells under catechol influence
2013
Petriccione, Milena | Forte, Valentina | Valente, Diego | Ciniglia, Claudia
Catechol is a highly toxic organic pollutant, usually abundant in the waste effluents of industrial processes and agricultural activities. The environmental sources of catechol include pesticides, wood preservatives, tanning lotion, cosmetic creams, dyes, and synthetic intermediates. Genotoxicity of catechol at a concentration range 5 × 10(-1)-5 mM was evaluated by applying random amplified polymorphic DNA (RAPD) and time-lapse DNA laddering tests using onion (Allium cepa) root cells as the assay system. RAPD analysis revealed polymorphisms in the nucleotidic sequence of DNA that reflected the genotoxic potential of catechol to provoke point mutations, or deletions, or chromosomal rearrangements. Time-lapse DNA laddering test provided evidence that catechol provoked DNA necrosis and apoptosis. Acridine orange/ethidium bromide staining could distinguish apoptotic from necrotic cells in root cells of A. cepa.
اظهر المزيد [+] اقل [-]Distribution coefficients of potentially toxic elements in soils from the eastern Amazon
2013
de Souza Braz, Anderson Martins | Fernandes, Antônio Rodrigues | Ferreira, José Roberto | Alleoni, Luís Reynaldo Ferracciú
The solid-solution distribution or partition coefficient (Kd) is a measure of affinity of potentially toxic elements (PTE) for soil colloids. Kd plays a key role in several models for defining PTE guideline values in soils and for assessing environmental risks, and its value depends on edaphic and climatic conditions of the sites where the soils occur. This study quantified Kd values for Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn from representative soil samples from Brazil’s eastern Amazon region, which measures 1.2 million km². The Kd values obtained were lower than those set by both international and Brazilian environmental agencies and were correlated with the pH, Fe and Mn oxide content, and cationic exchange capacity of the soils. The following order of decreasing affinity was observed: Pb > Cu > Hg > Cr > Cd ≈ Co > Ni > Zn.
اظهر المزيد [+] اقل [-]The legacy of persistent organic pollutants in Azerbaijan: an assessment of past use and current contamination
2013
Aliyeva, Gulchohra | Halsall, Crispin | Alasgarova, Khoshgadam | Avazova, Matanat | Ibrahimov, Yaqub | Aghayeva, Roya
Azerbaijan has a history of production and heavy use of organochlorine pesticides (OCPs) with use focused in the main agricultural lowland region centred on the Kur River. Using a number of data sources, including archived reports from several government ministries, we attempt to construct production and use inventories for dichlorodiphenyltrichloroethane (DDT) and HCHs and compare these to scientific estimates of production and use of these chemicals in the 1960s to the 1980s. Notable discrepancies are evident particularly for DDT, with Azeri government records indicating much higher use (147-fold) than that estimated by the international scientific community. Soil and river sediment data from the 1980s and 2000s are also presented. While it is recognised that analytical uncertainties remain high for these older data (generated by GC–ECD), there is some evidence to show a decline in concentrations for some OCPs over this period. Extremely high concentrations of OCPs are evident for soils sampled in the vicinity of obsolete pesticide storage sites (found in numerous locations around the agricultural lowlands) and these levels may pose a health risk to wildlife and humans. River sediment data indicate high levels of both OCPs and polychlorinated biphenyls (PCBs), particularly downstream of the confluence of the two main rivers, the Kur and Araz. Particle-bound annual fluxes from the Kur River into the Caspian Sea are estimated for PCBs and OCPs and these are likely to influence levels observed in local coastal sediments, with agreement between river sediment data generated in the early 2000s and coastal marine sediment data generated from separate studies. We recommend that monitoring efforts should focus on soils in agricultural areas and around pesticide storage and production facilities as these soils will continue to provide a source of POPs to the regional environment.
اظهر المزيد [+] اقل [-]Coal fly ash as adsorptive material for treatment of a real textile effluent: operating parameters and treatment efficiency
2013
Zaharia, Carmen | Suteu, Daniela
The experimental results performed after the application of one single-stage treatment by sorption onto coal fly ash are evaluated in order to decolorize a real textile effluent of a private company specializing in manufacturing of cotton fabrics (i.e., sorption performance applied for a real textile effluent collected after the fabric dyeing, rinsing, and final finishing steps). The experiments are focused on studying the effect of initial textile effluent pH, adsorbent dose, temperature and adsorption time, considered as operating parameters of sorption process for high pollutant removals (e.g., organic pollutants as dyes, phenols, polymeric, and degradation compounds), and decoloration. The results indicate high values of decoloration degree (55.42–83.00 %) and COD removal (44.44–61.11 %) when it is worked at pH ≤2 with coal ash dose of 12–40 g/L, temperature higher than 20–25 °C, and continuous static operating regime (with an initial agitation step of 3–5 min). The treated textile effluent fulfills the quality demand, and is recyclable, inside reused or discharged after a stage of neutralization (standard pH of 6.5–8.5 for all textile effluent discharges). Also, the final effluent is able to follow the common path to the central biological treatment plant (i.e., a centralized treatment plant for all companies acting in the industrial site area with mechanical–biological steps for wastewater treatment) or may be directly discharged in the nearly watercourse.
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