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Influence of Riparian Seepage Zones on Nitrate Variability in Two Agricultural Headwater Streams 下载免费PDF全文
Mark R. Williams Anthony R. Buda Herschel A. Elliott Kamini Singha James Hamlett 《Journal of the American Water Resources Association》2015,51(4):883-897
Riparian seeps have been recognized for their contributions to stream flow in headwater catchments, but there is limited data on how seeps affect stream water quality. The objective of this study was to examine the effect of seeps on the variability of stream NO3‐N concentrations in FD36 and RS, two agricultural catchments in Pennsylvania. Stream samples were collected at 10‐m intervals over reaches of 550 (FD36) and 490 m (RS) on 21 occasions between April 2009 and January 2012. Semi‐variogram analysis was used to quantify longitudinal patterns in stream NO3‐N concentration. Seep water was collected at 14 sites in FD36 and 7 in RS, but the number of flowing seeps depended on antecedent conditions. Seep NO3‐N concentrations were variable (0.1‐29.5 mg/l) and were often greater downslope of cropped fields compared to other land uses. During base flow, longitudinal variability in stream NO3‐N concentrations increased as the number of flowing seeps increased. The influence of seeps on the variability of stream NO3‐N concentrations was less during storm flow compared to the variability of base flow NO3‐N concentrations. However, 24 h after a storm in FD36, an increase in the number of flowing seeps and decreasing streamflow resulted in the greatest longitudinal variability in stream NO3‐N concentrations recorded. Results indicate seeps are important areas of NO3‐N delivery to streams where targeted adoption of mitigation measures may substantially improve stream water quality. 相似文献
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Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application
in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers
of methyl acrylate onto mercerized Grewia optiva
biofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters
such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized
to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared
spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric
techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect
of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optiva
biofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical
and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by
using grafted Grewia optiva
biofibers as reinforcement. 相似文献
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Pal Swades Singha Pankaj 《Environmental science and pollution research international》2023,30(5):11634-11660
Environmental Science and Pollution Research - Flow modification pursuing dams is widely found. Some works also focused on its impact on floodplain wetland hydrology. However, how this change can... 相似文献
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Removal of Pb(II) ions from aqueous solution and industrial effluent using natural biosorbents 总被引:1,自引:0,他引:1
Purpose
The purpose of the research is to investigate the applicability of the low-cost natural biosorbents for the removal of Pb(II) ions from aqueous solution and effluent from battery industry.Methods
Six different biosorbents namely rice straw, rice bran, rice husk, coconut shell, neem leaves, and hyacinth roots have been used for the removal of Pb(II) ions from aqueous solution in batch process. All the biosorbents were collected from local area near Kolkata, West Bengal, India. The removal efficiency was determined in batch experiments for each biosorbent.Results
The biosorbents were characterized by SEM, FTIR, surface area, and point of zero charge. The sorption kinetic data was best described by pseudo-second-order model for all the biosorbents except rice husk which followed intraparticle diffusion model. Pb(II) ions adsorption process for rice straw, rice bran, and hyacinth roots were governed predominately by film diffusion, but in the case of rice husk, it was intraparticle diffusion. Film diffusion and intraparticle diffusion were equally responsible for the biosorption process onto coconut shell and neem leaves. The values of mass transfer coefficient indicated that the velocity of the adsorbate transport from the bulk to the solid phase was quite fast for all cases. Maximum monolayer sorption capacities onto the six natural sorbents studied were estimated from the Langmuir sorption model and compared with other natural sorbents used by other researchers. The Elovich model, the calculated values of effective diffusivity, and the sorption energy calculated by using the Dubinin?CRadushkevich isotherm were indicated that the sorption process was chemical in nature. The thermodynamic studies indicated that the adsorption processes were endothermic. FTIR studies were carried out to understand the type of functional groups responsible for Pb(II) ions binding process. Regeneration of biosorbents were carried out by desorption studies using HNO3. Battery industry effluents were used for the application study to investigate applicability of the biosorbents.Conclusion
The biosorbents can be utilized as low-cost sorbents for the removal of Pb(II) ions from wastewater. 相似文献6.
Natural cellulosic fibers are one of the smartest materials for use as reinforcement in polymers possessing a number of applications. Keeping in mind the immense advantages of the natural fibers, in present work synthesis of natural cellulosic fibers reinforced polymer composites through compression molding technique have been reported. Scanning Electron microscopy (SEM), Thermo gravimetric/Differential thermal/Derivative Thermogravimetry (TGA/DTA/DTG), absorption in different solvents, moisture absorbance, water uptake and chemical resistance measurements were used as characterization techniques for evaluating the different behaviour of cellulosic natural fibers reinforced polymer composites. Effect of fiber loading on mechanical properties like tensile strength, flexural strength, compressive strength and wear resistances has also been determined. Reinforcing of the polymer matrix with natural fibers was done in the form of short fiber. Present work indicates that green composites can be successfully fabricated with useful mechanical properties. These composites may be used in secondary structural applications in automotive, housing etc. 相似文献
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Rani Rupa Kela Abhidha Dhaniya Geeta Arya Kamini Tripathi Amit K. Ahirwar Rajesh 《Environmental science and pollution research international》2021,28(39):54282-54298
Environmental Science and Pollution Research - Exposure to polycyclic aromatic hydrocarbons (PAHs) produced from various pyrogenic and petrogenic sources in the environment has been linked... 相似文献
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A characterization of the atmospheric surface layer in coastal region of Qatar is presented in the present paper. The micrometeorological data is collected in the New Doha International Airport (25.25N, 51.62E), at a pier 500 m into the ocean by deploying tower based instruments during the month of June-2011. The normalized variance of the three components of velocity and temperature are studied within the framework of Monin–Obukhov similarity theory. The normalized variances of stream wise and transverse velocity at near-neutral condition are found to be consistent with the reported values from measurement sites around the world, but the normalized variance of vertical velocity at near-neutral condition is found to be consistently lower in the present case. The dependency of the normalized velocity variances with buoyancy parameter indicates a higher growth rate of variances, compared to other investigations. The non-dimensional variance of temperature matches well with the past investigations, but the correlation between vertical velocity and temperature indicates higher magnitude for the present location. 相似文献
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Present work deals with the surface modification of Cannabis indica fiber through benzoylation and graft copolymerization of acrylonitrile (AN) onto C. indica fibers under the influence of microwave radiations. The Benzoylation of C. indica fiber was carried out by treating raw fiber with varying concentrations of benzoyl chloride solution. Different reaction parameters for graft copolymerization, such as reaction time, initiator concentration, nitric acid concentration, pH and monomer concentration were optimized to get the maximum percentage of grafting (25.54%). A suitable mechanism to explain benzoylation and graft copolymerization has been also proposed. Raw C. indica fiber, graft copolymerized and benzoylated fibers were subjected to evaluation of some of their properties like swelling behavior, moisture absorbance and resistance towards chemicals. Cannabis indica fibers treated with 5% benzoyl chloride solution and AN graft copolymerized fibers have been found to show more resistant towards moisture, water and chemicals when compared with that of untreated fibers. Morphological, structural changes, thermal stability and crystallanity of raw, graft copolymerized and benzoylated fibers have also been studied by SEM, FTIR, TGA and XRD techniques. It has been observed that the crystallinity of fiber decreases but thermal stability increases on surface modification. 相似文献
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