Sorption of non-ionic surfactants to soil: the role of soil mineral composition

In this study, the importance of individual soil mineral constituents on non-ionic surfactant sorption is evaluated by employing scanning electron microscopy (SEM) equipped with energy-dispersive X-ray analysis (EDAX) to observe microchemical surface composition of model soil colloids and relate surface microchemical composition to the sorption behavior of a non-ionic surfactant, Polyethylene Glyco Mono-p-nonylphenyl Ether (A9PE10), on selected model soil colloids. This information is critical to understanding the fate and transport of this class of contaminants in subsurface. Results obtained from this study indicate that a correlation between the atomic ratio of Si:(Al + Fe) on soil mineral surface and A9PE10 sorption capacity exist, where those soil with larger value of Si:(Al + Fe) ratio exhibit higher sorption capacity. This allows us to predict that the non-ionic surfactant sorption capacity for soil decrease with progressively increasing states of soil maturity.     

A method for removal of CO from exhaust gas using pulsed corona discharge

An experimental study of the oxidation of CO in exhaust gas from a motorcycle has been carried out using plasma chemical reactions in a pulsed corona discharge. In the process, some main parameters, such as the initial CO concentration, amplitude and frequency of pulses, residence time, reactor volume, and relative humidity (RH), as well as their effects on CO removal characteristics, were investigated. O3, which is beneficial to reducing CO, was produced during CO removal. When the exhaust gas was at ambient temperature, more than 80% CO removal efficiency was realized at an initial concentration of 288 ppm in a suitable range of the parameters.     

Oxidant stress, antioxidants and nitric oxide in traffic police of Hyderabad, India

Exposure to environmental pollutants is known to be harmful to health, in general, and to lungs in particular. In this respect, traffic police are at particular risk due to the nature of their job, since they are exposed to emissions from the vehicles. Here, we show that in the traffic police of Hyderabad city, India, the plasma levels of lipid peroxides are high, whereas the concentrations of the nitric oxide are low. In addition, the levels of various antioxidants in the RBC lysate such as catalase, superoxide dismutase and glutathione peroxidase were found to be low with no significant alteration in plasma ceruloplasmin levels. These results suggest that exposure to air pollutants, a major portion of which is due to emissions from the vehicles, can increase oxidant stress, decrease the levels of antioxidants and nitric oxide. This imbalance in the oxidant/antioxidant system may lead to lung damage and is likely to cause respiratory problems in individuals exposed to air pollution.     

Treatment of ethylether in air stream by a biotrickling filter packed with slags.

This paper reports results of studies using a biotrickling filter with blast-furnace slag packings (sizes = 2-4 cm and specific surface area = 120 m2/m3) for treatment of ethylether in air stream. Effects of volumetric loading, superficial gas velocity, empty bed gas retention time, recirculation liquid flow rate, and biofilm renewal on the ethylether removal efficiency and elimination capacity were tested. Results indicate that ethylether removal efficieincies of more than 95% were obtained with an empty bed retention time (EBRT) of 113 sec and loadings of lower than 70 g/m3/hr. At an EBRT of 57 sec, removal efficiencies of more than 90% could only be obtained with loadings of lower than 35 g/m3/hr. The maximum elimination capacities were 71 and 45 g/m3/hr for EBRT = 113 and 57 sec, respectively. The maximum ethylether elimination capacities were 71 and 96 g/m3/hr, respectively, before and after the renewal at EBRT = 113 sec. With an EBRT of 113 sec and a loading of lower than 38 g/m3/hr, the removal efficiency was nearly independent of the superficial liquid recirculation velocity in the range of 3.6 to 9.6 m3/m2/hr. From data regression, simplified masstransfer limited, and reaction- and mass-transfer limited models correlating the contaminant concentration and the packing height were proposed and verified. The former model is applicable for cases of low influent contaminant concentrations or loadings, and the latter is applicable for cases of higher ones. Finally, CO2 conversion efficiencies of approximately 90% for the influent ethylether were obtained. The value is comparable to data reported from other related studies.     

Growth, respiration and nitrogen content in needles of Scots pine exposed to elevated ozone and carbon dioxide in the field

Single Scots pine (Pinus sylvestris L.) trees, aged 30 years, were grown in open-top chambers and exposed to two atmospheric concentrations of ozone (O3; ambient and elevation) and carbon dioxide (CO2) as single variables or in combination for 3 years (1994-1996). Needle growth, respiration and nitrogen content were measured simultaneously over the period of needle expansion. Compared to ambient treatment (33 nmol mol(-1) O3 and 350 micromol mol(-1) CO2) doubled ambient O3 (69 nmol mol(-1)) significantly reduced the specific growth rates (SGRs) of the needles in the early stage of needle expansion and needle nitrogen concentration (N1) in the late stage, but increased apparent respiration rates (ARRs) in the late stage. Doubled ambient CO2 (about 650 micromol mol(-1)) significantly increased maximum SGR but reduced ARR and N1 in the late stage of needle expansion. The changes in ARR induced by the different treatments may be associated with treatment-induced changes in needle growth, metabolic activities and turnover of nitrogenous compounds. When ARR was partitioned into its two functional components, growth and maintenance respiration, the results showed that neither doubled ambient O3 nor doubled ambient CO2 influenced the growth respiration coefficients (Rg). However, doubled ambient O3 significantly increased the maintenance respiration coefficients (Rm) regardless of the needle development stage, while doubled ambient CO2 significantly reduced Rm only in the late stage of needle expansion. The increase in Rm under doubled ambient O3 conditions appeared to be related to an increase in metabolic activities, whereas the decrease in Rm under doubled ambient CO2 conditions may be attributed to the reduced N1 and turnover rate of nitrogenous compounds per unit. The combination of elevated O3 and CO2 had very similar effects on growth, respiration and N1 to doubled ambient O3 alone, but the interactive mechanism of the two gases is still not clear.     

Metal accumulation in tissues of seabirds from Chaun, northeast Siberia, Russia

Concentrations of four essential elements (Fe, Mn, Zn, and Cu) and two toxic metals (Cd and Hg) were determined in selected tissues of 11 seabird species collected in Chaun, northeast Siberia. In oldsquaw, arctic tern and herring gull, zinc concentrations were correlated with Cd concentrations. Cadmium concentrations in all the species were highest in kidney and Hg in liver. Cd levels in the liver and kidney of herring gulls were higher than those observed from other breeding areas. Similarly, Hg concentrations were also high in the liver of herring gull. High concentrations of Cd and Hg found in some birds from Chaun might have arisen from exposure on migration.     

Relationship between copper speciation in sediments and bioaccumulation by marine bivalves of Taiwan

This paper evaluates the relationships between copper species in sediments and accumulation by the purple clam (Hiatula diphos) and venus clam (Gomphina aeguilatera) collected from the field and culture (aquaculture) ponds in the polluted coastal area of Lukang, Taiwan. Sediment was sampled along with the molluscs, including oysters (Crassostrea gigas), purple clams (Hiatula diphos), rock-shells (Thais clavigera), venus clams (Gomphina aeguilatera), and hard clams (Meretrix lusoria), from two unique environments of Lukang during the period from August 1993 to July 1994. The data indicate that the total copper concentrations in sediments from culture ponds (185 microg g(-1)) was higher than those of the field (44.0 microg g(-1)). Copper species in sediments were analyzed by a sequential leaching technique. Results show that concentrations of various copper species in the sediments are in the range of 1.14 +/- 0.59 to 13.2 +/- 22.4 microg g(-1) and 0.36 +/- 0.24 to 133 +/- 36.7 microg g(-1) for the two environments, respectively. Also the exchangeable copper in sediment from culture ponds was 15 times higher than that from the field. In addition, the sum of exchangeable and copper carbonates had the highest percentages of copper in both the pond sediment (86.6 %) and the field sediment (50.7 %). Maximum copper concentrations (309 +/- 35.1 microg g(-1)) in oysters were much higher than those in the other benthic organisms by about 4-127 times. Similarly, the data also showed that copper concentrations in Thais clavigera were 12-32 times higher than those in other benthic organisms. Copper concentrations in various benthic organisms differed significantly (p < 0.05) from that in Thais clavigera. This capacity makes Thais clavigera a potential candidate for monitoring copper in marine sediments. In terms of copper species, the best correlation was generally obtained between copper carbonates in sediments and copper concentrations in Hiatula diphos (r = 0.886*). A strong multiple regression correlation (p < 0.05, r2 = 0.7894) also indicates that the copper carbonates may dominate as the available form of copper to Hiatula diphos from various environments in the Lukang coastal area under natural physicochemical conditions.     

Assessing ozone-precursor relationships based on a smog production model and ambient data

A semi-empirical model, Johnson's smog production model (SPM), which relates precursor emissions to ozone levels and estimates the relative effectiveness of volatile organic compounds (VOC) and NOx emission controls, has been evaluated and a modified version of SPM has been introduced. Both versions have been applied to routine data from 1989-1991 in five areas in the United States. In particular, extent parameters, which reveal the relative merit of VOC and NOx controls in reducing high ozone levels, have been calculated. Preliminary applications of SPM reveal interesting features with respect to VOC vs. NOx controls in reducing high ozone levels. For hourly data with ozone > or =0.08 ppm, distributions of extent parameters resulting from the modified SPM show the effectiveness of VOC controls at more monitoring sites than those from Johnson's SPM; however, relative features between the two versions are similar. On the other hand, for hourly data with ozone > or =0.12 ppm, the two SPM versions show very similar relative effectiveness of VOC and NOx controls with chosen values of model parameters. To improve the credibility of SPM, the range of validity of relationships between maximum smog produced or maximum ozone and NOx concentrations must be determined, and the parameters in these relationships must be better determined for typical VOC mixtures. Another essential parameter, which determines the fractional loss of NOy (NO and its oxidation products) from the gas phase must be better determined.     

An operational assessment of the application of the relative reduction factors in the demonstration of attainment of the 8-hr ozone National Ambient Air Quality Standard

The U.S. Environmental Protection Agency in 1997 revised the 1-hr ozone (O3) National Ambient Air Quality Standard (NAAQS) to one based on an 8-hr average, resulting in potential nonattainment status for substantial portions of the eastern United States. The regulatory process provides for the development of a state implementation plan that includes a demonstration that the projected future O3 concentrations will be at or below the NAAQS based on photochemical modeling and analytical techniques. In this study, four photochemical modeling systems, based on two photochemical models, Community Model for Air Quality and the Comprehensive Air Quality Model with extensions, and two emissions processing models, Sparse Matrix Optimization Kernel for Emissions and Emissions Modeling System, were applied to the eastern United States, with emphasis on the northeastern Ozone Transport Region in terms of their response to oxides of nitrogen and volatile organic carbon-focused controls on the estimated design values. With the 8-hr O3 NAAQS set as a bright-line test, it was found that a given area could be termed as being in or out of attainment of the NAAQS depending upon the modeling system. This suggests the need to provide an estimate of model-to-model uncertainty in the relative reduction factor (RRF) for a better understanding of the uncertainty in projecting the status of an area's attainment. Results indicate that the model-to-model differences considered in this study introduce     

Rapid reductive destruction of hazardous organic compounds by nanoscale Fe0

Fe0-mediated reductive destruction of hazardous organic compounds such as chlorinated organic compounds (COCs) and nitroaromatic compounds (NACs) in the aqueous phase is one of the latest innovative technologies. In this paper, rapid reductive degradation of COCs and NACs by synthesized nanoscale Fe0 in anaerobic batch systems was presented. The nanoscale Fe0, characterized by high specific surface area and high reactivity, rapidly transformed trichloroethylene (TCE), chloroform (CF), nitrobenzene (NB), nitrotoluene (NT), dinitrobenzene (DNB) and dinitrotoluene (DNT) under ambient conditions, which results in complete disappearance of the parent compounds from the aqueous phase within a few minutes. GC analysis reported that the main products of the dechlorination of TCE and CF were ethane and methane as well as that most of the nitro groups in NACs were reductively transformed to amine groups. These results suggest that the rapid reductive destruction by nanoscale Fe0 is potentially a viable in situ or aboveground treatment of groundwater contaminated with hazardous organic compounds including COCs and NACs.