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Resultados 1871-1880 de 4,033
Sorption of Atrazine, 17α-Estradiol, and Phenanthrene on Wheat Straw and Peanut Shell Biochars
2016
Zhou, Jiangmin | Chen, Hualin | Huang, Weilin | Arocena, Joselito M. | Ge, Shimei
Biochars from two different feedstocks (peanut shell-PB; wheat straw-WB) were used in this study to understand the sorption mechanisms of atrazine (ATR), 17α-ethinyl estradiol (EE2), and phenanthrene (PHEN) to help minimize the bioavailability of the organic pollutants in the environment. Sorption isotherms of ATR, EE2, and PHEN by WB and PB biochars followed the Freundlich model where the sorption parameter (n) shows the trend: ATR > EE2 and PHEN, while the sorption capacity (log K ₒc) increases from ATR < EE2 < PHEN and indicate that the most hydrophobic and planar organic pollutant (PHEN) is the most easily adsorbed organic compound on PB and WB. The higher H/C and (O + N)/C ratios of WB (0.099 and 0.525, respectively) suggest its stronger aliphaticity and polarity than PB (0.078 and 0.352, respectively) that induced stronger sorption affinity for ATR and PHEN. Higher specific surface area (m² g⁻¹) of PB (19.7) may be responsible for the higher sorption capacity for EE2 than WB (8.8) because it can accommodate the large molecule of EE2. Results from this study may be helpful to predict the bioavailability of organic pollutants when soils contaminated with pollutants are remediated with biochars produced from wheat straw and peanut shells.
Mostrar más [+] Menos [-]Effects of Saline Water Irrigation and N Application Rate on NH3 Volatilization and N use Efficiency in a Drip-Irrigated Cotton Field
2016
Zhou, Guangwei | Zhang, Wen | Ma, Lijuan | Guo, Huijuan | Min, Wei | Li, Qi | Liao, Na | Hou, Zhenan
Ammonia (NH₃) volatilization is one of the main pathways of N loss from farmland soil. Saline water irrigation can have direct or indirect effects on soil NH₃ volatilization, N leaching, and crop N uptake. This study was conducted to evaluate the effects of irrigation water salinity and urea-N application rate on NH₃ volatilization and N use efficiency in a drip-irrigated cotton field. The experiment consisted of three levels of irrigation water salinity: fresh water, brackish water, and saline water (electrical conductivities of 0.35, 4.61, and 8.04 dS/m, respectively). The N application rates were 0, 240, 360, and 480 kg/ha. The results showed that soil salinity and soil moisture content were significantly higher in the saline water treatment than in either the fresh or brackish water treatments. Irrigation water salinity significantly increased soil NH₄-N concentration, but NO₃-N concentration decreased as water salinity increased. The amount of N leaching varied from 5.0 to 25.5 kg/ha, accounting for 1.81 to 4.79 % of the urea-N applied under different water salinity and N application rate treatments. Both the amount of N leaching and the proportions of applied N lost through leaching significantly increased as water salinity increased. N application increased the amounts of N leaching, but the ratios of applied N were not affected by N application rate. Soil NH₃ volatilization increased rapidly after urea fertigation, and peaked at 1–2 days after N application, then decreased rapidly. The amount of NH₃ volatilization varied from 9.0 to 33.7 kg/ha, accounting for 3.2 to 3.8 % of the N applied in all treatments. Soil NH₃ volatilization was significantly higher in the saline water treatment than that in either the fresh or the brackish water treatments. Cotton N uptake increased significantly as N application rate increased, but decreased with irrigation water salinity increased. In conclusion, saline water irrigation with high N application rate induced high N leaching and NH₃ volatilization losses, thereby dramatically reducing the apparent N recovery (ANR) of cotton.
Mostrar más [+] Menos [-]Impact of Anions, Cations, and pH on Manganese Accumulation and Toxicity in the Green Alga Scenedesmus quadricauda
2016
Švec, Pavel | Kováčik, Jozef | Hedbavný, Josef | Babula, Petr | Rotková, Gabriela | Klejdus, Bořivoj
Accumulation of divalent manganese (Mn) and its toxicity in the green alga Scenedesmus quadricauda was studied at circumneutral pH (6.5). A comparison of two applied concentrations (10 or 100 μM) of MnCl₂, MnSO₄, and Mn(NO₃)₂ indicated that mainly sulfate evoked higher Mn accumulation. On the other hand, nitrate rather depleted antioxidative enzyme activities (APX, CAT, SOD), leading to an increase in ROS formation as proven by fluorescence microscopy. Subsequent experiments revealed that increase in pH (from 4.5 to 9.5) increased also Mn content but typically depleted amounts of reduced glutathione and phytochelatin 2. We also measured the size of particles formed from the manganese salts at pH 9.5. Competitive experiment between Ca/K salts (CaCl₂, CaSO₄, Ca(NO₃)₂, KCl, K₂SO₄, KNO₃) and Mn (as Mn sulfate) showed a negative relation between Ca and Mn amount but KNO₃ stimulated Mn accumulation. Microscopy revealed that mainly K salts elevated plasma membrane damage (Acridine orange staining). Data indicate that not only pH but also accompanying anion affects Mn accumulation and that Ca salts may affect Mn toxicity.
Mostrar más [+] Menos [-]Assessment of Toxic Metal Uptake by Different Vegetables Grown on Soils Amended with Poultry Waste: Risk Assessment
2016
Sahito, Oan Muhammad | Kazi, Tasneem Gul | Afridi, Hassan Imran | Baig, Jameel Ahmed | Talpur, Farah Naz | Baloch, Shahnawaz | Memon, Nusrat Shahab | Kori, Nasreen Gul
The use of poultry waste (without proper treatment) as a potential fertilizer in agricultural soils have great concern to environment and human health, due to high levels of organic and inorganic toxicants, including heavy metals. Thus, the aim of this study was to monitor and assess bio-accumulation of heavy metals, cadmium (Cd), copper (Cu), Iron (Fe), lead (Pb), and zinc (Zn) contained in soil amended with poultry waste (SPW) and compared with controls. The physico-chemical parameters and heavy metal concentration in control soil (CS), poultry waste (PW), and SPW samples was also determined. The comparison study between the test vegetables and controls showed that the concentrations of Cd, Cu, Fe, Pb, and Zn in edible parts of chili pepper were found to be 0.057, 38.0, 61.9, 1.02, and 51.1 mg kg⁻¹, respectively, while the levels of Cd, Cu, Fe, Pb, and Zn were 0.14, 28.7, 138, 3.67, and 64.7 mg kg⁻¹, respectively, in coriander grown on SPW. The uptakes of heavy metals in test vegetables were found to be 35.7 to 95.6 % higher as compared with control vegetables. Soil-to-vegetable transfer factor values for all heavy metals in test samples were higher than control samples (p < 0.05). The enrichment factor values were >1.05, which indicated that the source of heavy metal contamination in the studied area was anthropogenic. Graphical Abstract Fate of heavy metals from poultry manure to agricultural soil
Mostrar más [+] Menos [-]Determination the Usefulness of AhHMA4p1::AhHMA4 Expression in Biofortification Strategies
2016
Weremczuk, Aleksandra | Barabasz, Anna | Ruszczyńska, Anna | Bulska, Ewa | Antosiewicz, Danuta Maria
AhHMA4 from Arabidopsis thaliana encodes Zn/Cd export protein that controls Zn/Cd translocation to shoots. The focus of this manuscript is the evaluation of AhHMA4 expression in tomato for mineral biofortification (more Zn and less Cd in shoots and fruits). Hydroponic and soil-based experiments were performed. Transgenic and wild-type plants were grown on two dilution levels of Knop’s medium (1/10, 1/2) with or without Cd, to determine if mineral composition affects the pattern of root/shoot partitioning of both metals due to AhHMA4 expression. Facilitation of Zn translocation to shoots of 19-day-old transgenic tomato was noted only when plants were grown in the more diluted medium. Moreover, the expression pattern of Zn-Cd-Fe cross-homeostasis genes (LeIRT1, LeChln, LeNRAMP1) was changed in transgenics in a medium composition-dependent fashion. In plants grown in soil (with/without Cd) up to maturity, expression of AhHMA4 resulted in more efficient translocation of Zn to shoots and restriction of Cd. These results indicate the usefulness of AhHMA4 expression to improve the growth of tomato on low-Zn soil, also contaminated with Cd.
Mostrar más [+] Menos [-]Effects of Mediators for Ligninolytic Enzyme Production and Kinetic Studies on Degradation of Pentachlorobenzene by Trametes versicolor U80
2016
Sari, Ajeng Arum | Yasin, Hasbi | Tachibana, Sanro | Hadibarata, Tony
Pentachlorobenzene is one new persistent organic pollutants (POPs) that has been recently added to the Stockholm Convention on Persistent Organic Pollutants. Based on this reason, one treatment having ability to degrade this compound is needed. The microbiological process by using white-rot fungus was used in this experiment. Free cell of Trametes versicolor U80 degraded pentachlorobenzene 43 % in liquid medium at 40 days incubation. The rapid initial uptake of pentachlorobenzene was obtained in the first 20 days. The results based on ionization potential and the partial least square function indicated that both enzymatic systems of lignin peroxidase and P-450 monooxygenase involved in the degradation of pentachlorobenzene. By using addition of Tween 80, MnSO₄, and veratryl alcohol, degradation of pentachlorobenzene could be improved. Based on kinetic study, the use of 1 % of Tween 80 showed the highest degradation rate (2.0619/day) and the degradation of pentachlorobenzene by 50 % can be shortened up to 24 days. Application of T. versicolor U80 in soil and bioreactor degraded pentachlorobenzene 43 and 50 % at 40 days, respectively. T. versicolor U80 shows good capability degrading pentachlorobenzene in soil and bioreactor although it is lower than in liquid due to the difference of pollutant accessibility and transfer oxygen. Finally, strain T. versicolor U80 can be proposed as an excellent candidate for remediation application in pentachlorobenzene pollution.
Mostrar más [+] Menos [-]Effects of copper deficiency and copper toxicity on organogenesis and some physiological and biochemical responses of Scots pine (Pinus sylvestris L.) seedlings grown in hydroculture
2016
Ivanov, Yury V. | Kartashov, Alexander V. | Ivanova, Alexandra I. | Savochkin, Yury V. | Kuznetsov, Vladimir V.
The morphological, physiological, and biochemical parameters of 6-week-old seedlings of Scots pine (Pinus sylvestris L.) were studied under deficiency (1.2 nM) and chronic exposure to copper (0.32, 1, 2.5, 5, and 10 μM CuSO₄) in hydroculture. The deposit of copper in the seed allowed the seedlings to develop under copper deficiency without visible disruption of growth. The high sensitivity of Scots pine to the toxic effects of copper was shown, which manifested as a significant inhibition of growth and development. The loss of dominance of the main root and a strong inhibition of lateral root development pointed to a lack of adaptive reorganization of the root system architecture under copper excess. A preferential accumulation of copper in the root and a minor translocation in aerial organs confirmed that Scots pine belongs to a group of plants that exclude copper. Selective impairment in the absorption of manganese was discovered, under both deficiency and excess of copper in the nutrient solution, which was independent of the degree of development of the root system. Following 10 μM CuSO₄ exposure, the absorption of manganese and iron from the nutrient solution was completely suppressed, and the development of seedlings was secured by the stock of these micronutrients in the seed. The absence of signs of oxidative stress in the seedling organs was shown under deficiency and excess of copper, as evidenced by the steady content of malondialdehyde and 4-hydroxyalkenals. Against this background, no changes in total superoxide dismutase activity in the organs of seedlings were revealed, and the increased content of low-molecular-weight antioxidants was observed in the roots under 1 μM and in the needles under 5 μM CuSO₄ exposures.
Mostrar más [+] Menos [-]Heavy Metal Pollution in Urban Soil from 1994 to 2012 in Kaifeng City, China
2016
Liu, Dexin | Li, Yimeng | Ma, Jianhua | Li, Can | Chen, Xing
Heavy metal pollution in urban soil has become a serious environmental issue in China since the last three decades. Attention has been given to the investigation of soil contamination; however, there is little information available on the variation of heavy metal pollution in soils. To resolve this problem and provide references on similar regions, 18 topsoil (0∼20 cm) samples were collected from identical sites of districts that with different functions in Kaifeng City in 1994 and 2012. Total contents of As, Cd, Hg, and Pb were determined by standard methods. The variation of heavy metal pollution was evaluated by using geoaccumulation index and pollution load index. Results show a descending trend in heavy metal pollution of soil in Kaifeng City that demonstrated over the last 20 years, though there are still some contaminations in 2012. The highest concentration of soil metal was observed in industrial district, followed by the cultural and educational district, administrative business district, and entertaining district in turn. Concentrations of Pb in all soils and As in most soils were higher in 2012 than that in 1994, which mainly due to the rapid increase of motor vehicles and domestic garbage. Meanwhile, the concentrations of Hg and Cd in most soils were lower in 2012 than that in 1994, as the relocation and shutdown of industry and the wide development of environmental facilities. Land use and land cover change in urban areas can effect on soil metal pollution. When farmland transforms into urban land, the concentrations of soil metals would be increased, and also, the soil pollution will increase severely.
Mostrar más [+] Menos [-]Seasonal Variability in Stormwater Quality Treatment of Permeable Pavements Situated Over Heavy Clay and in a Cold Climate
2016
Winston, Ryan J. | Davidson-Bennett, Keely M. | Buccier, Kristen M. | Hunt, W. F. (William Frederick)
Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-winter water quality performance of two side-by-side permeable pavements in the Ohio snowbelt. The permeable interlocking concrete pavements were designed to drain impervious catchments 2.2 (large) and 7.2 (small) times larger than their surface area, were located over clay soils, and incorporated the internal water storage design feature. Nutrient reduction was similar to past studies—organic nitrogen and particulate phosphorus were removed through filtration and settling, while dissolved constituents received little treatment. Because of 16 and 32 % volume reductions in the small and large installations, respectively, nutrient loads were often significantly reduced but generally by less than 50 %. Aluminum, calcium, iron, magnesium, lead, chloride, and total suspended solids (TSS) concentrations and loads often increased after passing through the permeable pavements; effluent TSS loads were three- to five-fold higher than influent TSS loads. This was apparently due to seasonal release of clay- and silt-sized particles from the soils underlying the permeable pavement and inversely related to elapsed time since winter. The application of de-icing salt is thought to have caused deflocculation of the underlying soils, allowing particulates to exit with stormwater as it discharged from the underdrain of the permeable pavements. By autumn, both permeable pavements discharged metals and TSS concentrations similar to others in the literature, suggesting the de-icing effects lasted 3–6 months post-winter. Sodium may substantially affect the performance of permeable pavements following winter de-icing salt application, particularly when 2:1 clay minerals, such as vermiculites and smectites, predominate.
Mostrar más [+] Menos [-]Evaluation of Glass Wool Filters and Hollow-Fiber Ultrafiltration Concentration Methods for qPCR Detection of Human Adenoviruses and Polyomaviruses in River Water
2016
Ahmed, W. | Gyawali, P. | Toze, S.
Pathogenic human viruses cause over half of gastroenteritis cases associated with recreational water use worldwide. They are difficult to concentrate from environmental waters due to low numbers and small sizes. Rapid enumeration of viruses by quantitative polymerase chain reaction (qPCR) has the potential to improve water quality analysis and risk assessment. However, capturing and recovering these viruses from environmental water remain formidable barriers to routine use. Here, we compared the recovery efficiencies of human adenoviruses (HAdVs) and human polyomaviruses (HPyVs) from 10-L river water samples seeded with raw human wastewater (100 and 10 mL) using hollow-fiber ultrafiltration (HFUF) and glass wool filter (GWF) methods. The mean recovery efficiencies of HAdVs in river water samples through HFUF were 36 and 86 % for 100 and 10 mL of seeded human wastewater, respectively. In contrast, the estimated mean recovery efficiencies of HAdVs in river water samples through GWF were 1.3 and 3 % for 100 and 10 mL seeded raw human wastewater, respectively. Similar trends were also observed for HPyVs. Recovery efficiencies of HFUF method were significantly higher (P < 0.05) than GWF for both HAdVs and HPyVs. Our results clearly suggest that HFUF would be a preferred method for concentrating HAdVs and HPyVs from river water followed by subsequent detection and quantification with PCR/qPCR assays.
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