The relationships between fine particle light scattering extinction coefficient, relative humidity and temperature can be used to quantify sulfate mass concentration and composition for laboratory generated and ambien...
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The relationships between fine particle light scattering extinction coefficient, relative humidity and temperature can be used to quantify sulfate mass concentration and composition for laboratory generated and ambient aerosols. This measurement involves the use of an integrating nephelometer as well as a system for controlling the temperature and relative humidity of the air directly upstream of the nephelometer. Recent improvements in the control of these variables has subsequently enhanced the ability to detect the presence of sulfate compounds in complex atmospheric mixtures. Measurements at 2 urban sites (Seattle, Washington and Riverside, California) indicate the presence of fine particle sulfate compounds mixed with more volatile compounds. Measurements at a background site (Ozette Lake, Washington) indicate a mixture of acidic sulfate compounds with compounds that are less volatile than (NH4)2SO4.
Correction for ‘Emerging investigator series: quantitative insights into the relationship between the concentrations and SERS intensities of neonicotinoids in water’ by Shengdong Liu et al., Environ. Sci.: Nano, 202...
Correction for ‘Emerging investigator series: quantitative insights into the relationship between the concentrations and SERS intensities of neonicotinoids in water’ by Shengdong Liu et al., Environ. Sci.: Nano, 2024, 11, 3294–3300, https://***/10.1039/D4EN00221K.
River ice jam is one of the most important issues in rivers in cold regions during winter time. With the extra solid boundary due to the ice cover, the flow condition under ice-covered conditions is completely differe...
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River ice jam is one of the most important issues in rivers in cold regions during winter time. With the extra solid boundary due to the ice cover, the flow condition under ice-covered conditions is completely different from that of a open channel flow. The presence of bridge piers will further change the velocity field around the bridge piers. As a consequence, the formation and the accumulation of ice jams in the vicinity of the bridge pier will be affected. On the other side, the formation of an ice jam around the piers can cause extra turbulence to reduce the stability of a river bridge. The present study focuses on the stress analysis of the ice jam in the vicinity of a bridge pier. By developing a governing equation for describing the equilibrium state of an ice jam, the stability of the ice jam around bridge piers is analyzed and determined. As seen from the field data in literature, the stability estimations of an ice jam around bridge piers determined by the present method agree well with the field observations. Therefore, the proposed approach can be used for the prediction of the formation of ice jams around bridge piers.
Recent data collected in the Arctic have demonstrated the transport of atmospheric aerosol of anthropogenic origin into that region. Concern over the radiative effect of the highly-absorbing soot component of this aer...
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The results of preliminary screening tests comparing the total Hg(II) removal capacity of 11 different brands of commercial activated carbon indicated that a high percent (99-100%) total Hg removal was attained by all...
The results of preliminary screening tests comparing the total Hg(II) removal capacity of 11 different brands of commercial activated carbon indicated that a high percent (99-100%) total Hg removal was attained by all types of activated carbon especially at pH 4-5;the percent total Hg(II) removal decreased with pH .**GRAPHIC**. 4-5 except activated carbons Nuchar SA and SN which maintained a relatively high percent (> 90%) total Hg(II) removal capacity at all pH values. Experiments were conducted to reveal the mechanisms of Hg(II) removal by Nuchar SA (a powdered carbon). Total Hg(II) removal was achieved by 2 mechanisms, adsorption and reduction. In order to investigate the kinetics of these 2 reactions, volatilization by bubbling N2 gas at high flow rate was used to remove the Hg(g) product of the reduction reaction. The adsorption and reduction/volatilization reactions were highly pH-dependent;at pH .apprx. < 3-4 or > .apprx. 9-10 the extent of reduction/volatilization reaction superceded the adsorption reaction;in the mid-pH region adsorption reaction dominated total Hg(II) removal. The rate of adsorption reaction was fast, reaching equilibrium in a few minutes;the rate of reduction/volatilization followed a linear .sqroot. t [time] expression. The reduction reaction was more significant with Filtrasorb 400 (H-type carbon) than Nuchar SA (L-type carbon). In the presence of strong chelating agent, EDTA, the total Hg(II) removal decreased due partly to the formation of less adsorbably Hg(II)-EDTA complexes.
This article describes the design, construction, and evaluation of a visual colorimeter for use in studies of color perception in the natural environment. The colorimeter is portable, has a low power consumption, and ...
This article describes the design, construction, and evaluation of a visual colorimeter for use in studies of color perception in the natural environment. The colorimeter is portable, has a low power consumption, and produces luminances typical of those found outdoors. An asymmetric binocular‐matching procedure is used to match the colors of natural objects. The performance of the colorimeter was tested by comparing chromaticities of matches of colored papers to spectrophotometric measurements.
1. A two-season investigation was undertaken to determine the contribution of benthic recruitment to the population development of several species of blue-green algae. 2. Gloeotrichia echinulata populations were shown...
1. A two-season investigation was undertaken to determine the contribution of benthic recruitment to the population development of several species of blue-green algae. 2. Gloeotrichia echinulata populations were shown to be heavily subsidized by benthic recruitment, deriving on average 40% of their planktonic colonies from the benthos. 3. Benthic recruitment of Aphanizomenon flos-aquae;Anabaena flos-aquae and a second Anabaena species contributed less than 2% to planktonic increases, while Microcystis aeruginosa recruitment was negligible. 4. Phosphorus translocation via migrating G. echinulata accounted for most of the phosphorus (P) in the planktonic colonies, and constituted a significant portion of the internal loading of the lake. 5. Estimated P translocation via Aph. flos-aquae was relatively minor, although there was evidence of luxury uptake in the benthos.
Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from ClO2-bleached pulping studies at Insti...
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Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from ClO2-bleached pulping studies at Institute of Paper Science and Technology (IPST) were used as the feed for batch reactors to test and rank the treatability and kinetics. The key aspect of the system is the use of sequential anaerobic/aerobic phases to enhance reductive dehalogenation of chloro-organic materials. Two continuous reactor systems, one operated in an anaerobic-aerobic mode and a second in an aerobic-aerobic mode, received bleaching wastewater obtained from a full-scale plant. Acclimated cultures from both continuous reactors were used to quantify the AOX (Adsorbable Organic Halide) and COD removal from various bleaching wastewaters. In general, the sequential anaerobic/aerobic treatment of bleach wastewater can improve both biotreatability and degradation rates. (C) 1997 IAWQ.
A new technique has been developed for determination of optical depths δa as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is ...
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A new technique has been developed for determination of optical depths δa as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is not affected by the scattering properties of the absorber. This is accomplished by introducing the absorber into the virtually isotropic radiation field between two high-reflectance diffusing wafers and measuring the resultant attenuation of the transmitted light. The technique has been directed toward determination of the absorption coefficient of atmospheric aerosols in remote and relatively unpolluted locations. Provided appropriate collection filters and sampling conditions are used, the method can establish an absorption coefficient for the aerosol as low as 5 × 10?9 m?1 within a 10-h sampling period. A proportionally higher absorption coefficient requires proportionally less sample time. This paper discusses instrument design, the theoretical optical model, laboratory calibration, and a field test of the technique.
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