Removal of vaporous naphthalene using polyoxyethylenated nonionic surfactants

Previous research has demonstrated that an anionic surfactant can increase the solubility of the vapor phases of both naphthalene and sulfur dioxide in water. This study examines the feasibility of removing polycyclic aromatic hydrocarbons (PAHs) during gas absorption by adding the polyoxyethylenated nonionic surfactants tetraethylene glycol monodecyl ether (C10E4), octaethylene glycol monodecyl ether (C10E8), and octaethylene glycol monotetradecyl ether (C14E8), to water. The apparent solubility and absorption rates of naphthalene in surfactant solution were slightly higher than in pure water at a concentration lower than the critical micelle concentration (CMC). However, the apparent equilibrium naphthalene solubility increased linearly in proportion to the concentrations of nonionic surfactants because of the solubilization effect of micelles at concentrations above the CMC. The solubilization effect exceeded that of the reduced mass transfer coefficient, increasing the rate of absorption of vaporous naphthalene. For the four surfactants, the capacity to solubilize naphthalene was in the order C10E4 > C14E8 > C10E8 > sodium dodecyl sulfate (SDS) and was related to the hydrophile-lipophile balance values of the surfactants. The enrichment factors, which can express the degree of naphthalene solubility in solution, were 6.09-14.2 at a surfactant concentration of 0.01 M for the three polyoxyethylenated nonionic surfactants. Empirical findings confirm that adding nonionic surfactants increases the absorption efficiency of hydrophobic organic compounds (HOCs) using spray or packed tower.     

Horizontal distribution of butyltins in surface sediments from an enclosed bay system, Korea

Tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined from surface sediment samples (total 59 stations) covering a whole basin where harbors, shipyards, and aquaculture farms were located. Butyltin compounds were detected from all the stations covering 640 km(2) of an enclosed bay system. TBT concentrations ranged from 4 to 382 ng/g as tin on a dry weight basis, and total butyltin concentrations, from 27 to 1763 ng/g. Horizontal distribution of TBT concentration showed apparent negative gradients from harbors and shipyards, indicating that its contamination was closely related to boating and dry-docking activities. However, TBT concentrations were decreased steeply from source areas. Elevated DBT and MBT levels in creeks imply the possible input of DBT from industrial wastewater. Total butyltin concentrations in sediments are significantly correlated with particulate organic carbon concentration for the subset of stations that are distant from source areas.     

Estimating uncertainties and uncertainty contributors of CMB PM2.5 source apportionment results

The chemical mass balance (CMB) model was applied for source apportionment of PM_2.5 in Atlanta in order to explore levels and causes of uncertainties in source contributions. Monte Carlo analysis with Latin hypercube sampling (MC-LHS) was performed to evaluate the source impact uncertainties and quantify how uncertainties in ambient measurement and source profile data affect results. In general, uncertainties in the source profile data contribute more to the final uncertainties in source apportionment results than do those in ambient measurement data. Uncertainty contribution estimates suggest that non-linear interactions among source profiles also affect the final uncertainties although their influence is typically less than uncertainties in source profile data.     

Effect of agricultural antibiotics on the persistence and transformation of 17beta-estradiol in a Sequatchie loam

A laboratory incubation study was conducted to investigate the effect of agricultural antibiotics (sulfamethazine, tylosin, and chlortetracycline) on the persistence and transformation of 17beta-estradiol in Sequatchie loam. We measured concentrations of 17beta-estradiol and its primary metabolite (estrone) in soils spiked with antibiotics and 17beta-estradiol. Dehydrogenase activity (DHA) was also measured as an indicator of the total microbial activity of the soils. The presence of antibiotics significantly decreased transformation of 17beta-estradiol to estrone. There was a positive correlation between the DHA and the concentrations of estrone in soil spiked with 17beta-estradiol only, implying that the reaction is mainly catalyzed by dehydrogenases. However, the positive correlation was weakened in soil spiked with 17beta-estradiol and antibiotics together. We recommend that any study evaluating the fate and transport of estrogenic hormones in soil should include the effect of agricultural antibiotics because antibiotics and estrogenic hormones are commonly excreted together in environmental samples.     

Treatment of solutions with binary solutes using an admicellar enhanced CSTR: background solute effect

This study presents an admicellar enhanced continuous-flow stirred tank reactor (CSTR). Solutions containing single and binary aliphatic alcohols are introduced into this reactor for breakthrough experiments. Two phenomena occur during experiments with binary solutes: (a) a competitive effect caused by background solutes with relatively high hydrophobicity; (b) a co-solvent effect attributable to background solutes with relatively low hydrophobicity. The competition phenomenon and the corresponding mechanism involved are well demonstrated by directly monitoring the pre-adsolubilized solutes drawn out back to the solution while adsolubilizing other solutes with higher hydrophobicity. On the other hand, adsolubilization kinetics hindered by the background solute, which acts as a co-solvent, significantly alters the slopes of breakthrough curves of the target solute treated in the reactor.     

Metals in airborne particulate matter from the first and second industrial complex area of Taejon city, Korea

To understand the metal distribution characteristics in a rapidly urbanized area, we collected and analyzed particulate matter (PM) samples for the metal concentrations. Using our measurement data for various metal species, we examined both the extent of metal pollution in the study area and the seasonality in their distribution characteristics. Results showed that each metal exhibited their occurrences in diverse concentration ranges over several orders of magnitude such as the mean values ranging from minimum value of 0.07 (Be) to maximum value of 1633 ng m(-3) (Fe). In addition, the extent of metal pollution in the study area was in general comparable with those typically observed from a strongly polluted urban area, if comparison was made with the results of previous studies. Examinations of their temporal distribution patterns indicated that most of metals tend to exhibit seasonal peaks during winter (or spring) seasons, similarly to the observed pattern for PMs. Moreover to explain the factors regulating their mobilization properties, the data were analyzed through the application of correlation analysis. Results of our correlation analysis showed that most metals can exhibit strong positive correlations each other, while they tend to be inversely correlated with most of important meteorological parameters (including air temperature and precipitation). Based on the overall results of our study, we conclude that the site may be strongly impacted by man-made sources but that many characteristics of their cycling are not significantly different from those generally observed from natural environments.     

Effect of dissolved humic matters on the leachability of PCDD/F from fly ash--laboratory experiment using Aldrich humic acid

The effect of dissolved humic matters (DHM) on the leachability of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in fly ash was studied theoretically and in laboratorial condition to verify the previous results for pilot and field experiment of incineration residues landfill. In theoretical review, it was shown that DHM could influence the actual solubility and leachability of PCDD/F. The higher concentration of DHM showed the higher leachability of PCDD/F. In the leaching test, three different DHM concentrations and pHs of solutions were adopted to fly ash samples imaging the various characteristics of municipal solid waste leachate. It was proved experimentally that the leachability of PCDD/F increased with increasing DHM concentration in all pH conditions. The highest leachability was shown at the highest pH. Isomer distribution patterns of PCDD/F in all leachates were similar in all pH conditions. It backed up the distribution theory of PCDD/F between DHM and water.     

Persistence of carbofuran in marine sand and water

Marine sand and seawater samples were collected in March 2002 from Laysan Island in the Hawaiian Islands National Wildlife Refuge, where a small area was contaminated by the carbamate insecticide carbofuran. Carbofuran was still detected at microg g(-1) levels in the Laysan sand after its identification in 1998 and initial observation of the toxicity in 1988. The persistence of carbofuran in the marine sand was investigated in the dark in a 30 degrees C oven, and in distilled deionized water and seawater samples exposed to artificial 300 nm light and to direct sunlight. The laboratory study showed a half-life (t1/2) of approximately 40 days for carbofuran in the native sand and in Ottawa sand. The photolysis of carbofuran was faster in seawater than in distilled deionized water when it was exposed to 300 nm light (t1/2, 0.1 vs. 3.1 h) and to direct sunlight (t1/2, 7.5 vs. 41.6 h). The large difference between the laboratory results and the field observation of carbofuran dissipation suggests that carbofuran degradation at the remote, undisturbed marine site may be governed by its unique environmental factors.     

Anaerobic digestion of polyelectrolyte flocculated waste activated sludge

This work examined how adding one of three polyelectrolyte flocculants (T3052: cationic, T2000: non-ionic, and T1052: anionic) affected the anaerobic digestion of wastewater sludge. Methane production, floc characteristics (morphology and zeta-potential) and process parameters (soluble chemical oxygen demands (SCODs) and reductive potentials) were monitored along the digestion tests. The digestion rates of T2000- and T1052-conditioned sludge resembled that for original sludge. The T3052-flocculated sludge generated methane at a higher rate during the first 6 days of digestion than did the original one. In the following stage, the digestion rate of sludge flocculated with T3052 at dosage exceeding 15 g/kg dried solids declined. For example, at 40 days of digestion the methane production amounts for original, 15 g/kg DS flocculated, and 40 g/kg flocculated sludge were of 136, 105, and 85 g/kg DS, respectively. The role of flocculants could change in different stages of digestion.The dosed polymers had no apparent toxicity to the inoculum used. The changes in SCOD, adenosintriphosphate concentrations, oxidative and reductive potential, and zeta-potentials did not correlate with the noted hindered digestion for T3052-conditioned sludge. Microphotographic observation revealed that the flocs of T3052-conditioned sludge were not only of a large size, but also were resistant to structural deterioration during digestion. Therefore, mass transfer resistance was proposed to account for the hindered digestion efficiency observed for T3052-conditioned sludge.     

Determination of mutagenic potential and organic contaminants of Great Lakes drinking water

Extracts of organic compounds were obtained, using XAD-2 macroreticular resin, from drinking water supplies in 12 Great Lakes municipalities. The extracts were tested for mutagenic potential using the Salmonella/mammalian-microsome assay and analysed for organochlorine pesticides, polyaromatic hydrocarbons, organophosphorous pesticides and trialkyl-arylphosphates. Grab samples of drinking water were also analysed for volatile organic compounds. Dose-related increases in mutagenicity were found in extracts from 11 of the drinking water supplies.