Roadside measurements of size-segregated particulate organic compounds near gasoline and diesel-dominated freeways in Los Angeles,CA

Individual organic compounds such as hopanes and steranes (originating in lube oil) and selected polycyclic aromatic compounds (PAHs) (generated via combustion) found in particulate emissions from vehicles have proven useful in source apportionment of ambient particulate matter (PM). Detailed information on the size-segregated (ultrafine and accumulation mode) chemical characteristics of organic PM during the winter season originating from a pure gasoline traffic freeway (CA-110), and a mixed-fleet freeway with the highest fraction of heavy-duty diesel vehicles in the state of California (I-710) is reported in this study. Hopanes and steranes as well as high molecular weight PAHs such as benzo(ghi)perylene (BgP) and coronene levels are found comparable near these freeways, while elemental carbon (EC) and lighter molecular weight PAHs are found much elevated near I-710 compared to CA-110. The roadway organic speciation data presented here are compared with the emission factors (EFs) measured in the Caldecott tunnel, Berkeley, CA [Phuleria, H.C., Geller, M.D., Fine, P.M., Sioutas, C., 2006. Size-resolved emissions of organic tracers from light- and heavy-duty vehicles measured in a California roadway tunnel. Environmental Science and Technology 40, 4109–4118] for light-duty vehicles (LDVs) and heavy-duty vehicles. Very good agreement is observed between CA-110 measurements and LDV EFs as well as I-710 measurements and corresponding reconstructed EFs from Caldecott tunnel for hopanes and steranes as well as heavier PAHs such as BgP and coronene. Our results, therefore, suggest that the EFs for hopanes and steranes obtained in tunnel environments, where emissions are averaged over a large vehicle-fleet, enable reliable source apportionment of ambient PM, given the overall agreement between the roadway vs tunnel concentrations of these species.     

Radical/radical vs radical/molecule reactions in the formation of PCDD/Fs from (chloro)phenols in incinerators

Pathways from chlorinated phenols as precursors to PCDD/Fs are discussed with focus on the effect of (poly)chlorination on thermochemistry and rate in the displacement of chlorine from a chlorophenol molecule by a (chloro)phenoxy radical (reaction (A) as a key example). Through measurements on the respective methylethers (anisoles) the O-H bond of 2,4,6-TCP turns out to be 5 kcal/ mol, and that in PCP 4 kcal/mol, less strong than O-H in phenol itself. On this basis it is concluded that-in contrast with earlier proposals--displacements such as in reaction (A) are at least as slow as reaction (B) of phenoxy radical with chlorobenzene. PhO. + PhCl -->PhOPh + Cl. reaction B Compared with condensation of two (chloro)phenoxy radicals, such radical/molecule reactions are therefore an insignificant pathway to dioxins in incinerators.     

In situ experiment to determine advective-diffusive controls on solute transport in a clay-rich aquitard

Solute transport in clay-rich aquitards is characterized as molecular diffusion- or advection-dominated based on the Péclet number (P(e)). However, few field-based measurements of the coefficient of molecular diffusion (D(e)) exist, and none with a range of advection- or diffusion-dominated conditions in the same aquitard. In this long-term field experiment, standing water in a recovering well was spiked with deuterium ((2)H), then water-level recovery and δ(2)H values were monitored as the well returned to static conditions over 1054 days. After a second (2)H spike, water levels and δ(2)H values were monitored to day 1644 while under near static conditions. Modeling of the second spike was used to define the D(e) of (2)H as (3-4)× 10(-10)m(2)s(-1) for an accessible porosity of 0.31. Reservoir concentrations from the initial spike were modeled to define the transition from advection- to diffusion-dominated transport. This occurred after 200 days, consistent with a transition in P(e) from <1 to >1 when the length term is taken as the radial extent of the tracer plume (normalized concentration <0.05). This study verifies plume extent as the characteristic length term in the calculation of P(e) and demonstrates the transition from advection- to diffusion-dominated transport as the value of P(e) decreases below unity.     

Role of blue green algae biofertilizer in ameliorating the nitrogen demand and fly-ash stress to the growth and yield of rice (Oryza sativa L.) plants

Rice is a major food crop throughout the world; however, accumulation of toxic metals and metalloids in grains in contaminated environments is a matter of growing concern. Field experiments were conducted to analyze the growth performance, elemental composition (Fe, Si, Zn, Mn, Cu, Ni, Cd and As) and yield of the rice plants (Oryza sativa L. cv. Saryu-52) grown under different doses of fly-ash (FA; applied @ 10 and 100 tha(-1) denoted as FA(10) and FA(100), respectively) mixed with garden soil (GS) in combination with nitrogen fertilizer (NF; applied @ 90 and 120 kg ha(-1) denoted as NF(90) and NF(120), respectively) and blue green algae biofertilizer (BGA; applied @ 12.5 kg ha(-1) denoted as BGA(12.5)). Significant enhancement of growth was observed in the plants growing on amended soils as compared to GS and best response was obtained in amendment of FA(10)+NF(90)+BGA(12.5). Accumulation of Si, Fe, Zn and Mn was higher than Cu, Cd, Ni and As. Arsenic accumulation was detected only in FA(100) and its amendments. Inoculation of BGA(12.5) caused slight reduction in Cd, Ni and As content of plants as compared to NF(120) amendment. The high levels of stress inducible non-protein thiols (NP-SH) and cysteine in FA(100) were decreased by application of NF and BGA indicating stress amelioration. Study suggests integrated use of FA, BGA and NF for improved growth, yield and mineral composition of the rice plants besides reducing the high demand of nitrogen fertilizers.     

Comparing electron ionization high-resolution and electron capture low-resolution mass spectrometric determination of polybrominated diphenyl ethers in plasma, serum and milk

Gas chromatography coupled to low-resolution mass spectrometry with electron capture negative ionization as detection mode (GC-LRMS (ECNI)) has been compared to gas chromatography coupled to high-resolution mass spectrometry using electron ionization as detection mode (GC-HRMS (EI)) for determination of polybrominated diphenyl ethers (PBDEs) in biological samples. Extracts of 5.0 g plasma, serum and milk samples were analyzed using both methods. The GC-LRMS (ECNI) and GC-HRMS (EI) systems were found to be equally well suited for determination of PBDEs in the biological samples, as well as in standard solutions, with respect to response, detection limits and repeatability at the pg-level. The estimated limits of detection (LOD) in milk extracts ranged from 0.3-0.6 pg PBDE/g milk and 0.4-0.7 pg PBDE/g milk, for the GC-LRMS (ECNI) and GC-HRMS (EI) systems, respectively. The method repeatability including sample preparation was in the range 4.7-8.4% and 0.6-10% relative standard deviation (RSD) for the GC-LRMS (ECNI) and GC-HRMS (EI) systems, respectively.     

Heterogeneous photocatalysed reaction of three selected pesticide derivatives, propham, propachlor and tebuthiuron in aqueous suspensions of titanium dioxide

Heterogeneous photocatalysed reaction of three selected pesticide derivatives such as propham (1), propachlor (2) and tebuthiuron (3) has been investigated in aqueous suspensions of titanium dioxide by monitoring the change in substrate concentration employing UV Spectroscopic analysis and depletion in Total Organic Carbon (TOC) content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO(2) and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and ammonium persulphate (NH(4))(2)S(2)O(8) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts. The pesticide derivative propham (1) was found to degrade faster as compared to propachlor (2) and tebuthiuron (3). An attempt has also been made to identify the products formed during the photooxidation process through GC/MS analysis technique. All the model pollutants showed the formation of several intermediate products, which were identified on the basis of molecular ion and mass spectrometric fragmentation pattern. A probable mechanism for the formation of the products has been proposed.     

Effect of N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) on Cr(VI) reduction by Fe(II)

The complexation of Fe(II) with organic ligand results in the decrease of redox potential, and enhances the reduction ability of Fe(II). An important example is the use of Fe(II)-organic complexes to accelerate Cr(VI) reduction. Dissolved O(2) and light can potentially affect Cr(VI) reduction; however, these two factors have not been adequately evaluated. A batch technique was used to investigate the Cr(VI) reduction as influenced by the light and dissolved O(2) using N-hydroxyethyl-ethylenediamine-triacetic acid (HEDTA) and Fe(II) solutions. The oxidation of Fe(II) by dissolved O(2) was rapid in the presence of HEDTA at low pH; nonetheless, the oxidation proceeded slowly when HEDTA was absent. Although Cr(VI) could be reduced by free Fe(II) at low pH, the reaction was considerably slower than that of systems involving HEDTA. The enhancement of Cr(VI) reduction by Fe(II) in the presence of high concentrations of HEDTA was achieved as a result of two processes. First, HEDTA acted as a ligand for expediting electron transfer between Fe(II) and Cr(VI). Secondly, HEDTA served as a reductant for Cr(VI) under illumination.     

Transient behavior of heavy metals in soils during electrokinetic remediation

This paper presents a systematic bench-scale laboratory study performed to assess the transient behavior of chromium, nickel, and cadmium in different soils during electrokinetic remediation. A series of laboratory electrokinetic experiments was conducted using two different clayey soils, kaolin and glacial till. For each type of soil, four electrokinetic experiments with 1, 2, 4, and 10 d of treatment time were performed. In all tests, the contaminants were Cr(VI), Ni(II), and Cd(II) combined in the soil. A geochemical assessment was performed using the geochemical model MINEQL(+) to determine the partitioning of the heavy metals in soils as precipitated, adsorbed, and aqueous forms. Results showed that in kaolin, the extent of Ni(II) and Cd(II) migration towards the cathode increased as the treatment time increased. Unlike kaolin, in glacial till treatment time had no effect on nickel and cadmium migration because of its high buffering capacity. In both kaolin and glacial till, the extent of Cr(VI) migration towards the anode increased as the treatment time increased. However, Cr(VI) migration was higher in glacial till as compared to kaolin because of the high pH conditions that existed in glacial till. In all tests, some Cr(VI) was reduced to Cr(III), and the Cr(VI) reduction rate to Cr(III) as well as the Cr(III) migration were significantly affected by the treatment time. Overall, this study showed that the electroosmotic flow as well as the direction and extent of contaminant migration and removal depend on the polarity of the contaminant, the type of soil, and the treatment duration.     

Evaluation of mutagenic potential of contaminated atmosphere at Ibirapuera Park, São Paulo - SP, Brazil, using the Tradescantia stamen-hair assay

We report seasonal variation in CH(4) and N(2)O emission rate from solid storage of bovine manure in Delhi as well as emission factors and emission inventory from manure management systems in India. Emission flux observed in the year 2002-2003 was 4.29+/-1, 4.84+/-2.44 and 12.92+/-4.25 mg CH(4)kg(-1)dung day(-1), as well as 31.29+/-4.93, 72.11+/-16.22 and 6.39+/-1.76 microgN(2)O kg(-1)dung day(-1) in winter, summer and rainy seasons, respectively. CH(4) emission factors varied from 0.8 to 3.3 kg hd(-1)year(-1) for bovines and were lower than IPCC-1996 default values. N(2)O emission factors varied from 3 to 11.7 mg hd(-1)year(-1) from solid storage of manure. Inventory estimates were found to about 698+/-27 Gg CH(4) from all manure management systems and 2.3+/-0.46 tons of N(2)O from solid storage of manure for the year 2000.     

Kinetics and mechanism of TNT degradation in TiO2 photocatalysis

The photocatalytic degradation of TNT in a circular photocatalytic reactor, using a UV lamp as a light source and TiO(2) as a photocatalyst, was investigated. The effects of various parameters such as the initial TNT concentration, and the initial pH on the TNT degradation rate of TiO(2) photocatalysis were examined. In the presence of both UV light illumination and TiO(2) catalyst, TNT was more effectively degraded than with either UV or TiO(2) alone. The reaction rate was found to obey pseudo first-order kinetics represented by the Langmuir-Hinshelwood model. In the mineralization study, TNT (30 mg/l) photocatalytic degradation resulted in an approximately 80% TOC decrease after 150 min, and 10% of acetate and 57% of formate were produced as the organic intermediates, and were further degraded. NO(-)(3) NO(-)(2), and NH(+)(4) were detected as the nitrogen byproducts from photocatalysis and photolysis, and more than 50% of the total nitrogen was converted mainly to NO(-)(3)in the photocatalysis. However, NO(-)(3) did not adsorbed on the TiO(2) surface. TNT showed higher photocatalytic degradation efficiency at neutral and basic pH.     

The use of model compounds to elucidate metal forms in sewage sludge

Model phases of metal precipitates and organically bound metal were used to corroborate the nature of metal species found in sewage sludge by a sequential chemical extraction scheme. Model phase extractions supported the identification of the major species of Cd and Ni as carbonate (EDTA-extractable), Zn as organically-bound (Na(4)P(2)O(7)-extractable) and Pb as organically-bound or carbonate, although considerable overlap of fractions was apparent. Identification of the major species of Cu as sulphide (HNO(3)-extractable) could not be confirmed. The selectivity and efficiency of certain reagents was found to differ when used in sequence with other reagents, as opposed to being applied individually to model metal phases. Sample preparation was found to influence metal fractionation profiles in a model organic phase.     

Non-polar halogenated natural products bioaccumulated in marine samples. II. Brominated and mixed halogenated compounds

Several identified and potential natural brominated bioaccumulative compounds were studied in this work. 4,6-dibromo-2-(2('),4(')-dibromo)phenoxyanisole (BC-2) previously detected in Australian marine mammals and isolated from sponges, was synthesized. Two byproducts (a tetrabromo isomer and a tribromo congener) were investigated as well. The byproducts of the synthesis were not identified in the environmental samples investigated. Previously described natural brominated compounds (BC-1, BC-2, BC-3, BC-10, BC-11, MHC-1) and anthropogenic brominated diphenyl ethers (BDE-47, BDE-99, BDE-100, BDE-154) were detected in a sample of human milk. The sample was from a woman from the Faeroe Islands who frequently consumed fish as well as whale blubber and meat. The most abundant compound originated from the natural tetrabromo phenoxyanisole BC-3 which may have a 3:1 distribution of bromine on the two phenyl units. This sample also accumulated a dibromochloroanisole, as well as a previously unknown mixed halogenated compound (MHC-X) and an unknown, most likely aromatic brominated compound. Co-elutions on a DB-5 column were found for BDE-99 and BC-11 as well as BDE-154 and the unknown brominated compound. This suggests that quantification of these two compounds has to be carried out carefully.Two samples of lower trophic level, namely Baltic cod liver and Mexican mussel tissue, were investigated as well. The cod liver samples contained BDE congeners but also abundant signals for the natural 2,3,3('),4,4('),5,5(')-heptachloro-1(')-methyl-1,2(')-bipyrrole Q1 and tribromoanisole (TBA). The mussel sample contained Q1, TBA, another halogenated anisole, BC-1, BC-2, and BC-3, as well as additional, potential natural brominated compounds in the elution range of tribromophenoxyanisoles.     

Residual inorganic soil nitrogen in grass and maize on sandy soil

Nitrogen (N) remaining as inorganic ('mineral') soil N at crop harvest (N(minH)) contributes to nitrate leaching. N(minH) data from 20 (grass) and 78 (maize) experiments were examined to identify main determinants of N(minH). N-rate (A) explained 51% (grass) and 34% (maize) of the variance in N(minH). Best models included in addition crop N-offtake (U), offtake in unfertilised plots (U(0)), and N(minH) in unfertilised plots (N(minH,0)) and then explained up to 75% of variance. At low N-rates where apparent N recovery rho keeps to its initial value rho(ini), N(minH) keeps to its base level N(minH,0). At N-rates that exceed the value A(crit) where rho drops below rho(ini), N(minH) rises above N(minH,0) by an amount proportional to (rho(ini)-rho)A. About 80% of (rho(ini)-rho)A was found as N(minH,) in grass as well as in maize. The fraction (1-rho(ini))A does not appear to contribute to N(minH) at low N-rates (A< or =A(crit)) or at high N-rates (A>A(crit)).     

Methylation mechanism of tin(II) by methylcobalamin in aquatic systems

The methylation reaction of tin(II) with methylcobalamin (CH(3)B(12)) in aquatic systems was modeled in the laboratory. The products were detected by a sensitive gas chromatography-flame photometric detector (GC-FPD), and further identified by gas chromatography-mass spectrometry (GC-MS). Both monomethyltin (MMT) and dimethyltin (DMT) were found as methylation products. Three important effecting factors during the methylation reaction, salinity, pH and aerobic or anaerobic, were studied. The results showed that methyl group can be transferred from CH(3)B(12) to tin in aquatic solutions as a radical or carbonium, as well as a carbanion. Two explanations for the pH-dependency of the methylation reaction between tin(II) and CH(3)B(12) were proposed: pH-dependency of the equilibrium states of CH(3)B(12), and pH-dependency of inorganic tin(II) species whose reactivity vary with the redox potential in the solution. Salinity can influence the activity of the methyl donor, which cause changes in the methylation efficiency. Kinetic experiments showed that the methylation reaction was pseudo-first-order for CH(3)B(12).     

On the sedimentary occurrence of chlorophyllone a

The 13(2),17(3)-cyclopheophorbide a enol (CPP) is shown to convert mainly to a approximately 1:1 mixture of (13(2)R/S) chlorophyllones a (Chlone), when chromatographed over silica gel or alumina supports. 15(1)-hydroxychlorophyllonelactone a and some other chlorophyll a related compounds are also tentatively identified as minor transformation products of CPP. This raises the possibility that the chlorophyllones reported in recent sediments may be analytical artifacts from CPP. However, data for the surface sediments from Lake Motte as well as literature data for other contemporary sediments show that, (i) they are not artifacts, (ii) considering that CPP is the intermediate compound in the formation of chlorophyllones from chlorophyll a, the hydroxylation of CPP in the sedimentary environment involves an enzymatic process leading preferentially to 13(2)S chlorophyllone a.     

Assessment of organotin pollution along the Polish coast (Baltic Sea) by using mussels and fish as sentinel organisms

Levels of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), as well as triphenyltin (TPT), were monitored in 10 stations along the Polish coast (Baltic Sea). Mussel-Mytilus edulis-and fish-Platichthys flesus-were used as sentinel organisms. The bioaccumulation patterns of butyltin and phenyltin compounds varied substantially. Butyltins were detected in mussel tissue from all the sampled stations. Among them, organisms from the Gulf of Gdansk showed the highest residues (68 ng/g w.w. as Sn) in conjunction with elevated TBT/DBT ratios, which suggest recent inputs of TBT in the area. Additionally, flatfish were sampled in the Gulf of Gdansk, and different tissues (liver, digestive tube and gills) were analyzed separately. TPT, although undetected in mussels, was always present in fish. The highest organotin concentration was observed in the liver (369 ng/g w.w. as Sn) of fish caught near Gdansk port. Relatively high concentrations were observed in digestive tube, which points out the ingestion of organotin contaminated food as an important uptake route of those compounds in P. flesus.     

Biosorption of heavy metals using rice milling by-products. Characterisation and application for removal of metals from aqueous effluents

The morphological characteristics as well as chemical composition of rice husks were evaluated by different techniques such as spectroscopy and thermogravimetry. The material, which is considered a by-product obtained from rice milling, was then investigated as a potential decontaminant of toxic heavy metals present in laboratory effluents. Studies using glass columns were carried out at room temperature employing 100 ml of synthetic solutions containing Cd(II) and Pb(II) at 100 mg l(-1) in order to study the effects of pH, flow rate and particle size on Cd(II) and Pb(II) adsorption. After establishing the optimised conditions, the potentiality of rice husks for removing Cd(II) and Pb(II) ions from 100 ml of laboratory effluent, presenting concentrations before treatment of 22 and 12 mg l(-1), respectively, was evaluated. The ability to take up other metals species, such as Al(III), Cu(II) and Zn(II), present in this effluent was also studied. According to the data obtained, under the optimised conditions (pH=4.0, flow rate of 8.0 ml min(-1) and < or =355 microm rice husk particle size), 30 g of husks were necessary to attain the permissible limits for effluent release, as recommend by the EPA, for those species evolved in this work (Al, Cd, Cu, Pb and Zn).     

Investigation of a new approach to decompose two potent greenhouse gases: photoreduction of SF(6) and SF(5)CF(3) in the presence of acetone

In this paper, we addressed the utilization of photochemical method as an innovative technology for the destruction and removal of two potent greenhouse gases, SF(6) and SF(5)CF(3). The destruction and removal efficiency (DRE) of the process was determined as a function of excitation wavelength, irradiation time, initial ratio of acetone to SF(5)X (X represented F or CF(3)), initial SF(5)X concentration, additive oxygen and water vapor concentration. A complete removal was achieved by a radiation period of 55min and 120min for SF(6)-CH(3)COCH(3) system and SF(5)CF(3)-CH(3)COCH(3) system respectively under 184.9nm irradiation. Extra addition of water vapor can enhance DRE by approximately 6% points in both systems. Further studies with GC/MS and FT-IR proved that no hazardous products such as S(2)F(10), SO(2)F(2), SOF(2), SOF(4) were generated in this process.     

Species of copper and zinc in sediments collected from the antarctic ocean and the Taiwan Erhjin Chi coastal area

The species of copper and zinc, such as bioexchangeable, skeletal, easily reducible (Fe and Mn oxides), moderately reducible (crystalline Mn oxide), organic combined with sulfides, and detritus with minerals, in mud and sand, separated from the surface Antarctic Ocean and the Taiwan Erhjin Chi coastal (including river and estuarine) sediments, have been analyzed by sequential leaching methods. Results show that in the Antarctic Ocean sediments, high concentrations of total copper (128 mg/kg) and zinc (458 mg/kg) were found in the high mud (99.09%) content samples compared with the low concentrations of total copper (83.8 mg/kg) and zinc (288 mg/kg) in low mud (51.69%) content samples. High concentrations of copper, zinc, manganese and iron are possibly due to the characteristics of manganese nodules, in which the species of copper and zinc are mainly contained in the crystalline Mn oxide phase. In the Taiwan Erhjin Chi coastal sediments, the total copper and zinc concentrations in mud and sand vary with season and location. High values were generally observed in the river sediments during the dry season, and low values were in the estuarine and coastal sediments during the heavy rainy season. High percentages of copper (as high as 49.4%) and zinc (as high as 76.7%) in mud and sand were in the bioexchangeable phase including the skeletal phase. This result might be correlated with the problems arising from human impact on copper and zinc as well as sewage pollution in Taiwan. In the organic combined phase, biogenic particulate matter related to higher primary productivity in the Antarctic Ocean is also discussed.     

Removal mechanism of elemental mercury by using non-thermal plasma

The removal mechanism of elementary mercury (Hg(0)) by non-thermal plasma (NTP) has been investigated, where dielectric barrier discharge and O(3) injection methods as oxidation techniques are employed, together with the analysis of mercury species deposited on the reactor surface using temperature-programmed desorption and dissociation (TPDD) and scanning electron microscopy-energy dispersive spectroscopy. The removal of Hg(0) by NTP is found to be time-dependent and proceed through three domains; the Hg(0) concentration just slightly decreases as soon as NTP is initiated and then becomes constant for several minutes (Region 1), thereafter starts to decrease rapidly for 1h (Region 2) and, after passing fall-off region, very slowly decreases for about 4h (Region 3). The deposited mercury species on the reactor surface were conglomerated like islands, rather than dispersed uniformly, and their ratio of Hg(0) to O composition is observed to be 1:2. Additionally, the new peak in TPDD spectra observed in the region of 260-380°C is proposed as HgO(3). These results lead us to conclude that the deposited mercury species by NTP have extra O atoms to oxidize the adsorbed Hg(0), resulting in the acceleration of removal rate as the oxidation of Hg(0) proceeds.