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Effects of Ambient Ozone Concentrations on Contents of Nonstructural Carbohydrates in Phoebe bournei and Pinus massoniana Seedlings in Subtropical China Полный текст
2015
Chen, Zhan | Shang, He | Cao, Jixin | Yu, Hao
Ground-level ozone (O₃) pollution has affected carbon metabolism in tree species, which becomes one of the top environmental issues in China. In this paper, 1-year-old seedlings of Phoebe bournei and Pinus massoniana Lamb. were grown under field conditions at a rural site near the city of Taihe (Jiangxi Province). The plants were exposed in open-top chambers either to charcoal-filtered air or nonfiltered ambient air for 145 days. At the end of the growth season, the plants were harvested and the major nonstructural carbohydrates in leaves and roots were determined. Exposure to nonfiltered ambient air compared with filtered air controls caused an increase of sucrose, glucose, fructose, starch, and total nonstructural carbohydrates (TNCs) in fine roots of Ph. bournei, while there is no change in carbohydrate contents in Pi. massoniana roots. Compared with filtered air, in Ph. Bournei, starch and TNCs in leaves were reduced by 48 and 7 %, respectively, in ambient O₃. While, ambient O₃ just increased TNC content by 8.9 % in Pi. massoniana needles compared to filtered air. In summary, ambient O₃ affected carbohydrate metabolism of these two subtropical tree species in China, and Pi. massoniana was less sensitive than Ph. bournei. O₃ induced much greater changes in the amounts of carbohydrates in roots than in leaves.
Показать больше [+] Меньше [-]Bulk Deposition of Pesticides in a Canadian City: Part 1. Glyphosate and Other Agricultural Pesticides Полный текст
2015
Farenhorst, Annemieke | Andronak, L. A. | McQueen, R. D. A.
Winnipeg is a city in the Canadian Prairies with a population of about 600,000. Like many other cities and towns in this region of Canada, the city is surrounded by agriculture. Weekly bulk deposition samples were collected from May to September in 2010 and 2011 and analyzed for 43 pesticides used in Prairie agriculture. Fourteen herbicides, five herbicide metabolites, two insecticides, and two fungicides were detected with 98.5 % of the samples containing chemical mixtures. Glyphosate is the most widely used pesticide in Prairie agriculture and accounted for 65 % of the total pesticide deposition over the 2 years. Seasonal glyphosate deposition was more than five times larger in 2011 (182 mm rain) than 2010 (487 mm rain), suggesting increased glyphosate particulate transport in the atmosphere during the drier year. The seasonal deposition of ten other frequently herbicides was significantly positively correlated with the amount of herbicides applied both in and around Winnipeg (r = 0.90, P < 0.001) and with agricultural herbicide use around Winnipeg (r = 0.63, P = 0.05), but not with agricultural herbicide use province wide (P = 0.23). Herbicides 2,4-D (2,4-dichlorophenoxyacetic acid), dicamba, and mecoprop had known urban applications and were more consistently detected in samples relative to bromoxynil and 2-methyl-4-chlorophenoxyacetic acid (MCPA) whose frequency of detections decreased throughout August and September. The Canadian Water Quality Guidelines for irrigation water were frequently exceeded for both dicamba (75 %) and MCPA (49 %) concentrations in rain. None of glyphosate concentrations in rain exceeded any of the Canadian Water Quality Guidelines established for this herbicide.
Показать больше [+] Меньше [-]Phytotoxicity of Phenanthrene and Its Nitrogen Polycyclic Aromatic Hydrocarbon Analogues in Ageing Soil Полный текст
2015
Anyanwu, Ihuoma N. | Semple, K. T. (Kirk T.)
The impacts of phenanthrene and its nitrogen-containing analogues (N-PAHs) on seedling emergence and plant biomass of two terrestrial plant species, Lactuca sativa (lettuce) and Lolium perenne (rye grass), were investigated in soil over a 21-day exposure period. The data over 0–90-day soil-chemical contact time revealed that seedling emergence and plant biomass were significantly affected by N-PAHs even at the lowest concentration of 10 mg/kg. N-PAH amended soils showed greater inhibitory effects on seedling emergence and early plant biomass than phenanthrene amendments with incubations overtime. The degree of inhibition (% inhibition) on seedling emergence over time was 33.3 % (lettuce) and 46.7 % (rye grass) for the phenanthrene, and 53.3 % (lettuce) and 93.3 % (rye grass) for the N-PAHs, respectively, suggesting greater sensitivity of seedling emergence and early plant biomass on N-PAH-contaminated soil. The results from this study will contribute to data gaps for poorly managed chemicals/chemical groups for environmental risk assessment and might be useful in the development of new approaches for hazard assessment of contaminated systems.
Показать больше [+] Меньше [-]Salinization and Yield Potential of a Salt-Laden Californian Soil: an In Situ Geophysical Analysis Полный текст
2015
Cassel, Florence | Goorahoo, Dave | Sharmasarkar, Shankar
Salinization is a global problem, including in California, USA, where over two million hectares of irrigated lands have deteriorated due to salt loading. Because of freshwater shortage, some farmlands are also irrigated with agricultural drainage water, which further exacerbates the salinization process. With the objectives of rapidly quantifying spatial and temporal progression of salinization and identifying yield potential for a high-value crop, we conducted 2-year salinity surveys in a salt-affected farm in California by utilizing a dual dipole electromagnetic induction technology (EM38). The EM-predicted conductivity (ECₑ) was consistent with the ground-truth soil data ECₛ and increased with depth. About 50 and 25 % of the ECₑ data in moderately (A) and severely (B) affected salinity zones surpassed 500 and 1000 mS m⁻¹ levels, respectively. In the northern part of B, up to 70 % samples remained within 500–1000 mS m⁻¹ range. There was eastbound salt loading in the northern and southern parts of A. Rhizosphere salinity showed spatial dependence up to 500 m lateral distance. The shifts in salinity could be due to dispersion and leaching of solutes. High crop yield reduction was estimated in the southwestern and northeastern parts of the field that had typically elevated ECₑ. Around 43 % surveyed area was conducive to attaining 80 % of full yield potential, and the central part of the field was determined to be most suitable for crop growth. Coupling of EM results with production values indicated that under elevated saline condition, it would be feasible to grow a high-value tomato crop.
Показать больше [+] Меньше [-]Speciation in Application Environments for Dissolved Carbon Dioxide Sensors Полный текст
2015
Bhatia, Sonja | Risk, David
Measurement of the concentration of dissolved carbon dioxide in ground and surface aqueous environments is needed for a wide variety of scientific and industrial applications. These environments can be fresh, saline, or transitional in nature and can be hydrochemically complex. A next generation of sensors, like fiber-optic sensors, offer real-time, direct, distributed sensing of dissolved carbon dioxide and are an improvement over current technology for many applications; however, these sensors may be susceptible to signal disturbance when deployed in hydrochemically complex, natural environments. This complexity can best be characterized using hydrochemical modeling techniques. The modeling software, phreeqc 2.18, was used to conduct a comprehensive review to gain perspective on published data of natural water samples. Freshwater, saltwater, and transitional environments were characterized in terms of the distribution of carbonate and non-carbonate species present. Saline, transitional, and deep freshwater environments had the broadest range of carbonate distribution and species that may cross-interfere with sensor response. These data should be used to build complex laboratory test solutions that mimic the natural environment for use in sensor development. In some cases, specially engineered membranes may be required to mitigate the potentially cross-interfering effect of these ions.
Показать больше [+] Меньше [-]Constructed Wetland for Treating Effluent from Subtropical Aquaculture Farm Полный текст
2015
Travaini-Lima, Fernanda | da Veiga, Márcia Andreia Mesquita Silva | Sipaúba-Tavares, Lúcia Helena
A free water surface flow constructed wetland (CW) was designed to evaluate the capacity of this biological treatment system, which receives wastewater from aquaculture and upflow anaerobic sludge blanket (UASB) reactors, to retain heavy metal. The purpose of this study was to determine the role of the sediment and the macrophytes Cyperus giganteus, Typha domingensis, Eichhornia crassipes, and Pontederia cordata in accumulating Al, Cd, Cr, Cu, Fe, Ni, Mn, Pb, and Zn, during the dry (winter) and rainy (summer) seasons. In general, the concentrations and mass loading of heavy metals in the outlet water were lower than in the inlet water. The highest removal efficiency rates of water (mainly mass removal) occurred in the dry season. In the rainy season, the probable low oxygen level in the upper layer of sediment resulted in a release of reduced metals into the water because of organic matter mineralization and an increase in depth. This, coupled with an increase in the hydraulic loading rate (HLR), affected the efficiency removal in this season. The metals were especially immobilized as a result of the sedimentation process and could be removed weakly via macrophyte uptake, with the exception of Mn. In addition to the sediment, which is the main compartment for heavy metal retention in the CW system, the macrophytes have the advantage of being harvested. Therefore, E. crassipes and T. domingensis, which are good metal accumulators, can be recommended for the removal of heavy metals from agricultural wastewaters.
Показать больше [+] Меньше [-]Exploitation of Nano-Bentonite, Nano-Halloysite and Organically Modified Nano-Montmorillonite as an Adsorbent and Coagulation Aid for the Removal of Multi-Pesticides from Water: A Sorption Modelling Approach Полный текст
2015
Shabeer, T. P Ahammed | Saha, Ajoy | Gajbhiye, V. T. | Gupta, Suman | Manjaiah, K. M. | Varghese, Eldho
The objective of this study was to investigate the removal of multi-pesticides through a combined treatment process with coagulation–adsorption on nano-clay. Nano-clays like nano-bentonite, nano-halloysite and organically modified nano-montmorillonite were used as the adsorbent, and alum and polyaluminium chloride (PAC) were used as the coagulants. The coagulation method alone was not sufficient to purify water, whereas coagulation plus adsorption methods provided superior purification. Amongst the nano-clays used, organically modified nano-montmorillonite gave the best result in terms of pesticide removal from water. In order to evaluate the effect of coagulant addition on the removal efficiency of nano-clay, the respective adsorption isotherms were also calculated in the presence and absence of coagulants. Freundlich isotherm constants have shown that adsorption of pesticides on different nano-clay depends on the type of clay, presence and absence of coagulants as well as the properties of pesticides. The treatment combination having the maximum removal capacity was used efficiently for the removal of pesticides from natural and fortified natural water. The results indicated that alum–PAC coagulation aided by nano-clay as an adsorbent was the superior process for the simultaneous removal of multi-pesticides from water.
Показать больше [+] Меньше [-]Peatland Microbial Communities as Indicators of the Extreme Atmospheric Dust Deposition Полный текст
2015
Fiałkiewicz-Kozieł, B. | Smieja-Król, B. | Ostrovnaya, T. M. | Frontasyeva, M. | Siemińska, A. | Lamentowicz, M.
We investigated a peat profile from the Izery Mountains, located within the so-called Black Triangle, the border area of Poland, Czech Republic, and Germany. This peatland suffered from an extreme atmospheric pollution during the last 50 years, which created an exceptional natural experiment to examine the impact of pollution on peatland microbes. Testate amoebae (TA), Centropyxis aerophila and Phryganella acropodia, were distinguished as a proxy of atmospheric pollution caused by extensive brown coal combustion. We recorded a decline of mixotrophic TA and development of agglutinated taxa as a response for the extreme concentration of Al (30 g kg⁻¹) and Cu (96 mg kg⁻¹) as well as the extreme amount of fly ash particles determined by scanning electron microscopy (SEM) analysis, which were used by TA for shell construction. Titanium (5.9 %), aluminum (4.7 %), and chromium (4.2 %) significantly explained the highest percentage of the variance in TA data. Elements such as Al, Ti, Cr, Ni, and Cu were highly correlated (r > 0.7, p < 0.01) with pseudostome position/body size ratio and pseudostome position. Changes in the community structure, functional diversity, and mechanisms of shell construction were recognized as the indicators of dust pollution. We strengthen the importance of the TA as the bioindicators of the recent atmospheric pollution.
Показать больше [+] Меньше [-]Effect of Citric Acid, Rhizosphere Bacteria, and Plant Age on Metal Uptake in Reeds Cultured in Acid Mine Drainage Полный текст
2015
Guo, Lin | Cutright, Teresa J. | Duirk, Stephen
Acid mine drainage (AMD) poses serious environmental problems. This study assessed the effect of plant age, rhizosphere bacteria, and citric acid (CA) on the metal plaque formation and metal uptake in Phragmites australis cultured in a synthetic AMD solution. Iron-oxidizing bacteria (Fe(II)OB) enhanced the formation of Fe plaque, which slightly decreased Fe and Mn uptake. CA reduced the growth of Fe(II)OB and formation of Fe plaque, thereby increasing the Fe and Mn accumulations in reeds. Adult reeds had developed more Fe plaque on the root surface than seedlings. However, the adult reeds still accumulated higher concentrations of metals due to their higher tolerance to toxic environments and bigger biomass. With 9.02 g/L CA, adult reeds accumulated 0.51 ± 0.00 mg Mn, 109.38 ± 1.37 mg Fe, and 1.77 ± 0.04 mg Al. More investigation may be needed to further study the effect of CA when applied to AMD-contaminated field.
Показать больше [+] Меньше [-]Accumulation of Platinum Nanoparticles by Sinapis alba and Lepidium sativum Plants Полный текст
2015
Nanoparticles (NPs) are commonly used, and concerns about their possible adverse effects are being voiced as well. However, little is known about the fates of NPs released to the environment. The aim of the study was to (i) evaluate the ability of Sinapis alba and Lepidium sativum plants to take up platinum nanoparticles (Pt-NPs) and translocate them to aboveground organs, (ii) compare the accumulation efficiency of different forms of platinum and (iii) identify the forms in which platinum is stored in plant tissues. Plants were cultivated on medium supplemented with different concentrations of Pt-NPs and [Pt(NH₃)₄](NO₃)₂. Platinum content in plants was determined using inductively coupled plasma mass spectrometry. For the identification of the presence of Pt-NPs in plant tissues, gamma spectrometry following iron irradiation was applied. It was found that L. sativum and S. alba are tolerant to applied concentrations of Pt-NPs and have an ability to take up platinum from the medium and translocate it to aboveground organs. The highest concentration of platinum was observed in plant roots (reaching 8.7 g kg⁻¹for S. alba). We tentatively conclude that platinum is accumulated as nanoparticles. The obtained results suggest future application of plants for phytoremediation and recovery of noble metal nanoparticles.
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