Decolorization of azo dye reactive black B by Bacillus cereus strain HJ-1

Reactive black B (RBB) is a group of azo dyes that are widely used in the textile industry. In this study, a new microbial strain was isolated from azo dye contaminated river sediment which is capable of degrading RBB. The strain was identified as Bacillus cereus strain HJ-1 by 16S rRNA gene sequences analysis. The optimal conditions for RBB decolorization by B. cereus strain HJ-1 are: 25 °C, pH 8, 1 CMC of triton X-100, 0.15 g L^?1 of added yeast extract, 0.125 g L^?1 of added glucose and static culture. Then the toxicity of RBB on the green algae Chlorella vulgaris was determined. The results showed that the median effective concentration (EC₅₀) of RBB for C. vulgaris is 48 mg L^?1 and toxicity will really decrease after decolorization. In the end, B. cereus strain HJ-1 was amended into the origin river sediment and analyzed the whole microbial community structure of river sediment samples by PCR-DGGE technique. The result showed that B. cereus strain HJ-1 could survive in the river sediment after 12 d of incubation. Based on this work, we hope that these findings could provide some useful information for applying the decolorization of RBB in our environment.     

Measurements of atmospheric nitrous acid and nitric acid

A highly sensitive technique for the measurement of atmospheric HONO and HNO₃ is reported. The technique is based on aqueous scrubbing using two coil samplers, followed by conversion of HNO₃ to nitrite, derivatization of nitrite to a highly light-absorbing azo dye with sulfanilamide (SA) and N-(1-naphthyl) ethylenediamine (NED), and high performance liquid chromatography (HPLC) analysis. HNO₃ concentration was obtained by the difference of the two channels. Two scrubbing solutions were used for sampling the two species: a 1-mM phosphate buffer solution (pH 7) for the measurement of HONO and a 180 mM NH₄Cl/NH₃ buffer solution (pH 8.5) for the measurement of HONO+HNO₃. The scrubbing solution flow rate was 0.24 ml min⁻¹ and the gas sampling flow rate was 2 l min⁻¹. HNO₃ in the NH₄Cl/NH₃ buffer solution was quantitatively reduced to nitrite along an on-line 0.8-cm Cd reductor column. Nitrite in both channels was derivatized with 2 mM SA and 0.2 mM NED in 25 mM HCl. Quantitative derivatization was achieved within 5 min at 55°C. The azo dye derivative was then separated from the SA/NED reagent by reversed-phase HPLC and detected with a UV-vis detector at 540 nm. With an on-line SEP-PAK C-18 cartridge for the reagent purification, the method detection limit is estimated to be better than 1 pptv for HONO and about 20 pptv for HNO₃. The sample integration time was about 2 min and the sampling frequency is every 10 min. Data collected in downtown Albany and Whiteface Mountain, NY, are shown as examples of applications of this technique in both urban and remote clean environments.     

Preparation of controlled nano-MgO and investigation of its bactericidal properties

Nano-MgO is a good bactericide but with strong alkalinity in water due to its rapid hydrolysis. To control its hydrolysis rate and keep its bactericidal properties, we synthesized nano-MgO microspheres using chitosan–alginate system in this study. The synthesized nano-MgO release-controlled microspheres (nMgO-RCM) were with 0.98–1.20 mm of particle sizes. Also, their embedding ratio and loading percentage was 63.52% and 12.27%, respectively. Based on the characterization results, nano-MgO was only observed on surface of the nMgO-RCM. Its release rate from the nMgO-RCM could be controlled by the chitosan–alginate system, and the observed rate constant (k_obs) increased from 0.0289 h⁻¹ to 0.0358 h⁻¹ with the increment of the dosage from 10 mg L⁻¹ to 80 mg L⁻¹. Furthermore, the nMgO-RCM could maintain pH value lower than 8.5 and colony counts less than 20 CFU mL⁻¹ for at least 120 h.     

Fate of caffeine in mesocosms wetland planted with Scirpus validus

Uptake, accumulation and translocation of caffeine by Scirpus validus grown in hydroponic condition were investigated. The plants were cultivated in Hoagland’s nutrient solution spiked with caffeine at concentrations of 0.5–2.0 mg L^?1. The effect of photodegradation on caffeine elimination was determined in dark controls and proved to be negligible. Removal of caffeine in mesocosms without plants showed however that biodegradation could account for about 15–19% of the caffeine lost from solutions after 3 and 7 d. Plant uptake played a significant role in caffeine elimination. Caffeine was detected in both roots and shoots of S. validus. Root concentrations of caffeine were 0.1–6.1 μg g^?1, while the concentrations for shoots were 6.4–13.7 μg g^?1. A significant (p < 0.05) positive correlation between the concentration in the root and the initial concentrations in the nutrient solution was observed. The bioaccumulation factors (BAFs) of caffeine for roots ranged from 0.2 to 3.1, while BAFs for shoots ranged from 3.2 to 16.9. Translocation from roots to shoots was the major pathway of shoot accumulation. The fraction of caffeine in the roots as a percentage of the total caffeine mass in solution was limited to 0.2–4.4% throughout the whole experiment, while shoot uptake percentage ranged from 12% to 25% for caffeine at the initial concentration of 2.0 mg L^?1 to 50–62% for caffeine at the initial concentration of 0.5 mg L^?1. However, a marked decrease in the concentration of caffeine in the shoots between d-14 and d-21 suggests that caffeine may have been catabolized in the plant tissues subsequent to plant uptake and translocation.     

Henry’s law constant measurements for formaldehyde and benzaldehyde as a function of temperature and water composition

Henry’s law constants H of formaldehyde and benzaldehyde were determined using a dynamic system based on the water/air equilibrium at the interface within the length of a microporous tube. The measurements were conducted over the range 273–293 K in (i) deionized water, (ii) 35 g L^?1 solution of NaCl simulating seawater and (iii) two nitric acid solutions, i.e. 0.63 and 6.3 wt%.In pure water, the obtained data were used to derive the following Arrhenius expressions: ln H = (6423 ± 542)/T ? (13.4 ± 2.0) and ln H = (6258 ± 280)/T ? (17.5 ± 1.0) for formaldehyde and benzaldehyde, respectively. The H values, calculated at 293 K from Arrhenius expressions cited above were the following (in units of M atm^?1): H = 5020 ± 1170 (formaldehyde), H = 47 ± 5 (benzaldehyde). The temperature dependence of H permits then to derive the solvation enthalpies for both compounds: ΔH_solv = ?(53.4 ± 4.5) kJ mol^?1 and ΔH_solv = ?(52.0 ± 2.3) kJ mol^?1 for formaldehyde and benzaldehyde, respectively.In 35 g L^?1 salt solution, the H values were 27–66% and 12–21% lower than their respective determinations in deionized water, for formaldehyde and benzaldehyde respectively. The observed salt effect was used to estimate the following Setschenow coefficients at 293 K for 0.6 M NaCl: formaldehyde (0.21) and benzaldehyde (0.09).In 6.3 wt% nitric acid solution, H values of benzaldehyde were approximately 30% higher than those found in pure water although no significant influence was observed for formaldehyde.Finally, our experimental data were then used to estimate the fractions of formaldehyde and benzaldehyde in atmospheric aqueous phase and their derived atmospheric lifetimes.     

Receptor modeling of source apportionment of Hong Kong aerosols and the implication of urban and regional contribution

Understanding the spatial–temporal variations of source apportionment of PM_2.5 is critical to the effective control of particulate pollution. In this study, two one-year studies of PM_2.5 composition were conducted at three contrasting sites in Hong Kong from November 2000 to October 2001, and from November 2004 to October 2005, respectively. A receptor model, principal component analysis (PCA) with absolute principal component scores (APCS) technique, was applied to the PM_2.5 data for the identification and quantification of pollution sources at the rural, urban and roadside sites. The receptor modeling results identified that the major sources of PM_2.5 in Hong Kong were vehicular emissions/road erosion, secondary sulfate, residual oil combustion, soil suspension and sea salt regardless of sampling sites and sampling periods. The secondary sulfate aerosols made the most significant contribution to the PM_2.5 composition at the rural (HT) (44 ± 3%, mean ± 1σ standard error) and urban (TW) (28 ± 2%) sites, followed by vehicular emission (20 ± 3% for HT and 23 ± 4% for TW) and residual oil combustion (17 ± 2% for HT and 19 ± 1% for TW). However, at the roadside site (MK), vehicular emissions especially diesel vehicle emissions were the major source of PM_2.5 composition (33 ± 1% for diesel vehicle plus 18 ± 2% for other vehicles), followed by secondary sulfate aerosols (24 ± 1%). We found that the contribution of residual oil combustion at both urban and rural sites was much higher than that at the roadside site (2 ± 0.4%), perhaps due to the marine vessel activities of the container terminal near the urban site and close distance of pathway for the marine vessels to the rural site. The large contribution of secondary sulfate aerosols at all the three sites reflected the wide influence of regional pollution. With regard to the temporal trend, the contributions of vehicular emission and secondary sulfate to PM_2.5 showed higher autumn and winter values and lower summer levels at all the sites, particularly for the background site, suggesting that the seasonal variation of source apportionment in Hong Kong was mainly affected by the synoptic meteorological conditions and the long-range transport. Analysis of annual patterns indicated that the contribution of vehicular emission at the roadside was significantly reduced from 2000/01 to 2004/05 (p < 0.05, two-tail), especially the diesel vehicular emission (p < 0.001, two-tail). This is likely attributed to the implementation of the vehicular emission control programs with the tightening of diesel fuel contents and vehicular emission standards over these years by the Hong Kong government. In contrast, the contribution of secondary sulfate was remarkably increased from 2001 to 2005 (p < 0.001, two-tail), indicating a significant growth in regional sulfate pollution over the years.     

Extent of H-atom abstraction from OH + p-cymene and upper limits to the formation of cresols from OH + m-xylene and OH + p-cymene

Aromatic hydrocarbons are important constituents of vehicle exhaust and of non-methane volatile organic compounds in ambient air in urban areas. It has recently been proposed that dealkylation is a significant pathway for the OH radical-initiated reactions, leading to the formation of phenolic compounds and/or oxepins (Noda, J., Volkamer, R., Molina, M.J., 2009. Dealkylation of alkylbenzenes: a significant pathway in the toluene, o-, m-, and p-xylene + OH reaction. Journal of Physical Chemistry A 113, 9658–9666.). We have investigated the formation of cresols from the reactions of OH radicals with m-xylene and p-cymene, and obtain upper limits of <1% for formation of each cresol isomer from OH + m-xylene and <2% for formation of each cresol isomer from OH + p-cymene. In addition, we have measured the formation yield of 4-methylacetophenone (the major product formed subsequent to H-atom abstraction from the CH(CH₃)₂ group) in the OH + p-cymene reaction to be 14.8 ± 3.2%, and estimate that H-atom abstraction from the CH₃ and CH(CH₃)₂ groups in p-cymene accounts for 20 ± 4% of the overall OH radical reaction. We also used a relative rate technique to measure the rate constant for the reaction of OH radicals with 4-methylacetophenone to be (4.50 ± 0.43) × 10^?12 cm³ molecule^?1 s^?1 at 297 ± 2 K.     

Formation of hydrogen peroxide in the ozonolysis of isoprene and simple alkenes under humid conditions

The ozonolysis of isobutene and isoprene was performed in a 570 ℓ static reactor at 295 K and 730 Torr synthetic air in the presence and absence of water vapour, with the reactant concentration ranges of 1–6 ppmv. Products were analysed by a combination of FTIR spectroscopy, GC-FID, and HPLC. For both alkenes, the yields of H₂O₂ and the primary carbonyl products (acetone for isobutene, methacrolein and methylvinyl ketone for isoprene) increased under humid conditions. In the isoprene ozonolysis, the H₂O₂ yields relative to the O₃ conversion were, as determined from the initial rate of the formation, 1 and 9% for dry and humid conditions, respectively. The increase in its yield under the humid conditions was correlated with the sum of the increase in the yields of methacrolein and methylvinyl ketone (∼13%). This was explained by rapid decomposition of the transient α-hydroxy hydroperoxides formed in the reaction of H₂O with the two stabilised C₄ Criegee intermediates. Atmospheric relevance of the results is discussed.     

Seasonal soil and leaf CO2 exchange rates in a Mediterranean holm oak forest and their responses to drought conditions

We measured the soil and leaf CO₂ exchange in Quercus ilex and Phillyrea latifolia seasonally throughout the year in a representative site of the Mediterranean region, a natural holm oak forest growing in the Prades Mountains in southeastern Catalonia. In the wet seasons (spring and autumn), we experimentally decreased soil moisture by 30%, by excluding rainfall and water runoff in 12 plots, 1×10 m, and left 12 further plots as controls. Our aim was to predict the response of these gas exchanges to the drought forecasted for the next decades for this region by GCM and ecophysiological models.Annual average soil CO₂ exchange rate was 2.27±0.27 μmol CO₂ m⁻² s⁻¹. Annual average leaf CO₂ exchange rates were 8±1 and 5±1 μmol m⁻² s⁻¹ in Q. ilex and P. latifolia, respectively. Soil respiration rates in control treatments followed a seasonal pattern similar to photosynthetic activity. They reached maximum values in spring and autumn (2.5–3.8 μmol m⁻² s⁻¹ soil CO₂ emission rates and 7–15 μmol m⁻² s⁻¹ net photosynthetic rates) and minimum values (almost 0 for both variables) in summer, showing that soil moisture was the most important factor driving the soil microbial activity and the photosynthetic activity of plants. In autumn, drought treatment strongly decreased net photosynthesis rates and stomatal conductance of Q. ilex by 44% and 53%, respectively. Soil respiration was also reduced by 43% under drought treatment in the wet seasons. In summer there were larger soil CO₂ emissions in drought plots than in control plots, probably driven by autotrophic (roots) metabolism. The results indicate that leaf and soil CO₂ exchange may be strongly reduced (by ca. 44%) by the predicted decreases of soil water availability in the next decades. Long-term studies are needed to confirm these predictions or to find out possible acclimation of those processes.     

Ozone response to precursor controls: comparison of data analysis methods with the predictions of photochemical air quality simulation models

Comparisons were made between the predictions of six photochemical air quality simulation models (PAQSMs) and three indicators of ozone response to emission reductions: the ratios of O₃/NO_z and O₃/NO_y and the extent of reaction. The values of the two indicator ratios and the extent of reaction were computed from the model-predicted mixing ratios of ozone and oxidized nitrogen species and were compared to the changes in peak 1 and 8 h ozone mixing ratios predicted by the PAQSMs. The ozone changes were determined from the ozone levels predicted for base-case emission levels and for reduced emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NO_x). For all simulations, the model-predicted responses of peak 1 and 8 h ozone mixing ratios to VOC or NO_x emission reductions were correlated with the base-case extent of reaction and ratios of O₃/NO_z and O₃/NO_y. Peak ozone values increased following NO_x control in 95% (median over all simulations) of the high-ozone (>80 ppbv hourly mixing ratio in the base-case) grid cells having mean afternoon O₃/NO_z ratios less than 5 : 1, O₃/NO_y less than 4 : 1, or extent less than 0.6. Peak ozone levels decreased in response to NO_x reductions in 95% (median over all simulations) of the grid cells having peak hourly ozone mixing ratios greater than 80 ppbv and where mean afternoon O₃/NO_z exceeded 10 : 1, O₃/NO_y was greater than 8 : 1, or extent exceeded 0.8. Ozone responses varied in grid cells where O₃/NO_z was between 5 : 1 and 10 : 1, O₃/NO_y was between 4 : 1 and 8 : 1, or extent was between 0.6 and 0.8. The responses in such grid cells were affected by ozone responses in upwind grid cells and by the changes in ozone levels along the upwind boundaries of the modeling domains.     

Properties of organic matter in PM2.5 at Changdao Island,China—A rural site in the transport path of the Asian continental outflow

Fifty-five seasonal PM_2.5 samples were collected March 2003–January 2004 at Changdao, a resort island located at the demarcation line between Bohai Sea and Yellow Sea in Northern China. Changdao is in the transport path of the continental aerosols heading toward the Pacific Ocean in winter and spring due to the East Asia Monsoon. Solvent-extractable organic compounds (SEOC), organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were analyzed for source identification based on molecular markers. This data set provides useful information for the downstream site researchers of the Asian continental outflow. Total carbon (TC, OC+EC) was ∼18 μg m⁻³ in winter, ∼9 μg m⁻³ in spring and autumn and a large part of the TC was WSOC (33% in winter, >45% in the other seasons). Winter and spring were the high SEOC seasons with n-fatty acids the highest at ∼290 and ∼170 ng m⁻³, respectively, followed by n-alkanes at ∼210 and ∼90 ng m⁻³, and polycyclic aromatic hydrocarbons (PAHs) were also at high at ∼120 and ∼30 ng m⁻³. High WSOC/TC, low C_18:1/C₁₈ of fatty acids, and low concentrations of labile PAHs such as benzo(a)pyrene, together with back trajectory analysis suggested that the aerosols were aged and transported. PAHs, triterpane and sterane distributions provided evidence that coal burning was the main source of the continental outflow. The detection of levoglucosan and β-sitosterol in nearly all the samples showed the impact of biomass burning.     

Kinetics of the gas-phase reactions of NO3 radicals with ethyl acrylate,n-butyl acrylate,methyl methacrylate and ethyl methacrylate

The relative rate method has been used to determine the rate constants for the gas-phase reactions of NO₃ radicals with a series of acrylate esters: ethyl acrylate (k₁), n-butyl acrylate (k₂), methyl methacrylate (k₃) and ethyl methacrylate (k₄) at 298 ± 1 K and 760 Torr. The obtained rate constants are k₁ = (1.8 ± 0.25) × 10^?16 cm³ molecule^?1 s^?1, k₂ = (2.1 ± 0.33) × 10^?16 cm³ molecule^?1 s^?1, k₃ = (3.6 ± 1.2) × 10^?15 cm³ molecule^?1 s^?1, k₄ = (4.9 ± 1.7) × 10^?15 cm³ molecule^?1 s^?1. The experimental rate constants are in good agreement with theoretical rate constants calculated by an algorithm of the correlation between the rate constants and the orbital energies for the reactions of unsaturated VOCs with NO₃ radicals. In addition, the atmospheric lifetimes of the compound against NO₃ attack are estimated and the results show that NO₃ reactions contribute little to the atmospheric losses of acrylate esters except in polluted regions.     

Development and characterization of cell line from the gill tissue of Catla catla (Hamilton, 1822) for toxicological studies

Catla gill cell line (ICG) was established from gill tissue of Indian major carp (Catla catla), a freshwater fish cultivated in India. The cell line was maintained in Leibovitz’s L-15 supplemented with 10% fetal bovine serum. These cells have been sub-cultured more than 55 passages over a period of 2 years. The ICG cell line consists predominantly of epithelial-like cells. The cells were able to grow at a wide range of temperatures from 24 °C to 32 °C with an optimum temperature of 28 °C. The growth rate of gill cells increased as the fetal bovine serum (FBS) proportion increased from 2% to 20% at 28 °C with optimum growth at the concentrations of 10% or 15% FBS. Amplification of mitochondrial gene 12s rRNA using primers specific to C. catla confirmed the origin of this cell line from C. catla. The cells were successfully cryopreserved and revived at passage numbers 25, 35, 45 and 55. The cytotoxicity of three metal salts (ZnCl₂, CuSO₄ and CdCl₂) was assessed in ICG cell line using multiple endpoints such as MTT, Neutral Red assay, Alamar Blue assay and Coomassie Blue protein assay. Acute toxicity assay on fish were conducted by exposing C. catla for 96 h to three metal salts under static conditions. Statistical analysis revealed good correlation with r² = 0.908–0.985 for all combinations between endpoints employed. Linear correlations between each in vitro EC₅₀ and the in vivo LC₅₀ data were highly significant.     

Bioaccumulation of polybrominated diphenyl ethers in harbor seals from the northwest Atlantic

Polybrominated diphenyl ethers (PBDEs) were analyzed in blubber of harbor seals (Phoca vitulina concolor) collected between 1991 and 2005 along the northwest Atlantic. ∑PBDE concentrations (mono- to hexa-BDEs) detected in blubber samples (n = 42) ranged from 80 to 25 720 ng g⁻¹ lw, (overall mean 2403 ± 5406 ng g⁻¹ lw). By age, mean ∑PBDE concentrations were: 3645 ± 7388, 2945 ± 5995, 1385 ± 1265, and 326 ± 193 ng g⁻¹ lw in pups, yearlings, adult males, and adult females, respectively. Unlike the trend for PCBs, no decreasing gradient from urban to rural/remote areas was observed for PBDEs in these samples, likely reflecting inputs from local sources. No significant temporal trend was observed for PBDEs in harbor seals between 1991 and 2005, although congener profiles shifted over time. Tetra-BDE-47 was the dominant congener, followed by BDEs-99, -100, -153, -154, and -155 in varying order, suggesting exposure to the penta-BDE product. In adult males, the hexa-BDEs contributed more to the total (22%) than BDEs-99 and -100 (14%), and concentrations of BDE-155 were elevated compared with -154. Higher BDEs were detected in a subset of seals (n = 12) including hepta-BDE-183, the marker for the octa-BDE mixture, and octa-BDE-197, along with several unidentified hepta- and octa- congeners. BDE-209 was detected in seal blubber at concentrations ranging from 1.1 to 8 ng g⁻¹ lw, indicating that deca-BDE is bioavailable in this marine food web. This is the first study to document the accumulation of BDE-209 at measurable levels in wild harbor seals. While the PBDE patterns in blubber indicate exposure to all three BDE commercial mixtures, the data also suggest that BDE-209 debromination by seal prey fish may contribute to the loading of lower brominated congeners (hexa- to octa-BDEs) in these seals.     

Decadal reductions of traffic emissions on a transit route in Austria – results of the Tauerntunnel experiment 1997

Real-world emissions of a traffic fleet on a transit route in Austria were determined in the Tauerntunnel experiment in October 1997. The total number of vehicles and the average speed was nearly the same on both measuring days (465 vehicles 30 min⁻¹ and 76 km h⁻¹ on the workday, 477 and 78 km h⁻¹ on Sunday). The average workday fleet contained 17.6% heavy-duty vehicles (HDV) and the average Sunday fleet 2.8% HDV resulting in up to four times higher emission rates per vehicle per km on the workday than on Sunday for most of the regulated components (CO₂, CO, NO_x, SO₂, and particulate matter-PM10). Emission rates of NMVOC accounted for 200 mg vehicle⁻¹ km⁻¹ on both days. The relative contributions of light-duty vehicles (LDV) and HDV to the total emissions indicated that aldehydes, BTEX (benzene, toluene, ethylbenzene, xylenes), and alkanes are mainly produced by LDV, while HDV dominated emissions of CO, NO_x, SO₂, and PM10. Emissions of NO_x caused by HDV were 16,100 mg vehicle⁻¹ km⁻¹ (as NO₂). Produced by LDV they were much lower at 360 mg vehicle⁻¹ km⁻¹. Comparing the emission rates to the results that were obtained by the 1988 experiment at the same place significant changes in the emission levels of hydrocarbons and CO, which accounted 1997 to only 10% of the levels in 1988, were noticed. However, the decrease of PM has been modest leading to values of 80 and 60% of the levels in 1988 on the workday and on Sunday, respectively. Emission rates of NO_x determined on the workday in 1997 were 3130 mg vehicle⁻¹ km⁻¹ and even higher than in 1988 (2630 mg vehicle⁻¹ km⁻¹), presumable due to the increase of the HD-traffic.     

Exposure to cadmium in male urban and rural workers and effects on FSH,LH and testosterone

ObjectiveThis cross-sectional study was conducted to assess the relationship between exposure to cadmium and circulating reproductive hormone levels in urban and rural male workers.Materials and MethodsUrinary cadmium, blood cadmium, luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone were obtained from 86 non-smoking traffic policemen and 86 subjects working as roadmen in a rural area. All subjects were monitored to evaluate airborne exposure to cadmium.ResultsThe mean value of exposure to cadmium was 1.3 ng m^?3 in traffic policemen, while the mean value was less than 0.5 ng m^?3 in roadmen. The mean concentrations of urinary cadmium (1.4 vs. 0.9 μg g^?1 creatinine; p = 0.001), blood cadmium (1.1 vs. 0.7 μg l^?1; p = 0.000), FSH (2.6 vs. 3.2 μlU ml^?1; p = 0.02) and LH (2.6 vs. 3.1 μlU ml^?1; p = 0.03) were significantly different between traffic policemen and roadmen. No differences were found in the mean values of testosterone between the two groups. Multiple linear regression models showed associations between (a) urinary cadmium, airborne cadmium, working life, job category and consumption of water from water supply (b) blood cadmium, airborne cadmium and job category (c) the values of FSH and age, working life, job category, urinary cadmium and blood cadmium (d) the values of LH and both the age and working life.ConclusionThe above results must be confirmed by further studies, but they indicate the influence of exposure to the cadmium present in urban air on the circulating FSH, even at low doses.     

Treatment of high-ammonium anaerobic digester supernatant by aerobic granular sludge and ultrafiltration processes

Anaerobic sludge digester supernatant characterized by 569 mg TKN L^?1, high color and a COD/N ratio of 1.4 was treated in granular sequencing batch reactors (GSBRs) followed by post-denitrification (P-D) and ultrafiltration (UF) steps. The use of granular sludge allowed for the oxidation of ammonium in anaerobic digester supernatant at all investigated GSBR cycle lengths of 6, 8 and 12 h. The highest ammonium removal rate (15 mg N g^?1 VSS h^?1) with removal efficiency of 99% was noted at 8 h.Since the GSBR effluent was characterized by a high concentration of nitrites, slowly-degradable substances and biomass, additional purification steps were applied. In P-D stage, the microbial activity of granular biomass in the GSBR effluent was implemented. The P-D was supported by external carbon source addition and the most advantageous variant comprised dosing of half of the theoretical acetate dose for nitrite reduction in the 3-h intervals. The use of the system consisting of the GSBR with 8 h, an optimal P-D variant and a UF for the treatment of anaerobic digester supernatant allowed for the 99%, 71% and 97% reductions of TKN, COD and color, respectively.     

Comparison of measured and model-calculated real-world traffic emissions

The quality of an emission calculation model based on emission factors measured on roller test stands and statistical traffic data was evaluated using source strengths and emission factors calculated from real-world exhaust gas concentration differences measured upwind and downwind of a motorway in southwest Germany. Gaseous and particulate emissions were taken into account. Detailed traffic census data were taken during the measurements. The results were compared with findings of similar studies.The main conclusion is the underestimation of CO and NO_x source strengths by the model. On the average, it amounts to 23% in case of CO and 17% for NO_x. The latter underestimation results from an undervaluation by 22% of NO_x emission factors of heavy-duty vehicles (HDVs). There are significant differences between source strengths on working days and weekends because of the different traffic split between light-duty vehicles (LDVs) and HDVs. The mean emission factors of all vehicles from measurements are 1.08 g km⁻¹ veh⁻¹ for NO_x and 2.62 g km⁻¹ veh⁻¹ for CO. The model calculations give 0.92 g km⁻¹ veh⁻¹ for NO_x and 2.14 g km⁻¹ veh⁻¹ for CO.The source strengths of 21 non-methane hydrocarbon (NMHC) compounds quantified are underestimated by the model. The ratio between the measured and model-calculated emissions ranges from 1.3 to 2.1 for BTX and up to 21 for 16 other NMHCs. The reason for the differences is the insufficient knowledge of NMHC emissions of road traffic.Particulate matter emissions are dominated by ultra-fine particles in the 10–40 nm range. As far as aerosols larger than 29 nm are concerned, 1.80×10¹⁴ particles km⁻¹ veh⁻¹ are determined for all vehicles, 1.22×10¹⁴ particles km⁻¹ veh⁻¹ and an aerosol volume of 0.03 cm³ km⁻¹ veh⁻¹ are measured for LDVs, and for HDVs 7.79×10¹⁴ particles km⁻¹ veh⁻¹ and 0.41 cm³ km⁻¹ veh⁻¹ are calculated. Traffic-induced turbulence has been identified to have a decisive influence on exhaust gas dispersion near the source.     

Comparing the desorption and biodegradation of low concentrations of phenanthrene sorbed to activated carbon,biochar and compost

Carbonaceous soil amendments are applied to contaminated soils and sediments to strongly sorb hydrophobic organic contaminants (HOCs) and reduce their freely dissolved concentrations. This limits biouptake and toxicity, but also biodegradation. To investigate whether HOCs sorbed to such amendments can be degraded at all, the desorption and biodegradation of low concentrations of ¹⁴C-labelled phenanthrene (?5 μg L^?1) freshly sorbed to suspensions of the pure soil amendments activated carbon (AC), biochar (charcoal) and compost were compared. Firstly, the maximum abiotic desorption of phenanthrene from soil amendment suspensions in water, minimal salts medium (MSM) or tryptic soy broth (TSB) into a dominating silicone sink were measured. Highest fractions remained sorbed to AC (84 ± 2.3%, 87 ± 4.1%, and 53 ± 1.2% for water, MSM and TSB, respectively), followed by charcoal (35 ± 2.2%, 32 ± 1.7%, and 12 ± 0.3%, respectively) and compost (1.3 ± 0.21%, similar for all media). Secondly, the mineralization of phenanthrene sorbed to AC, charcoal and compost by Sphingomonas sp. 10-1 (DSM 12247) was determined. In contrast to the amounts desorbed, phenanthrene mineralization was similar for all the soil amendments at about 56 ± 11% of the initially applied radioactivity. Furthermore, HPLC analyses showed only minor amounts (<5%) of residual phenanthrene remaining in the suspensions, indicating almost complete biodegradation. Fitting the data to a coupled desorption and biodegradation model revealed that desorption did not limit biodegradation for any of the amendments, and that degradation could proceed due to the high numbers of bacteria and/or the production of biosurfactants or biofilms. Therefore, reduced desorption of phenanthrene from AC or charcoal did not inhibit its biodegradation, which implies that under the experimental conditions these amendments can reduce freely dissolved concentration without hindering biodegradation. In contrast, phenanthrene sorbed to compost was fully desorbed and biodegraded.     

Laboratory studies on the uptake of aromatic hydrocarbons by ice crystals during vapor depositional crystal growth

Uptake of aromatic hydrocarbons (AH) by ice crystals during vapor deposit growth was investigated in a walk-in cold chamber at temperatures of 242, 251, and 260 K, respectively. Ice crystals were grown from ambient air in the presence of gaseous AH namely: benzene (C₆H₆), toluene (methylbenzene, C₇H₈), the C₈H₁₀ isomers ethylbenzene, o-, m-, p-xylene (dimethylbenzenes), the C₉H₁₂ isomers n-propylbenzene, 4-ethyltoluene, 1,3,5-trimethylbenzene (1,3,5-TMB), 1,2,4-trimethylbenzene (1,2,4-TMB), 1,2,3-trimethylbenzene (1,2,3-TMB), and the C₁₀H₁₄ compound tert.-butylbenzene. Gas-phase concentrations calculated at 295 K were 10.3–20.8 μg m⁻³. Uptake of AH was detected by analyzing vapor deposited ice with a very sensitive method composed of solid-phase micro-extraction (SPME), followed by gas chromatography/mass spectrometry (GC/MS).Ice crystal size was lower than 1 cm. At water vapor extents of 5.8, 6.0 and 8.1 g m⁻³, ice crystal shape changed with decreasing temperatures from a column at a temperature of 260 K, to a plate at 251 K, and to a dendrite at 242 K. Experimentally observed ice growth rates were between 3.3 and 13.3×10⁻³ g s⁻¹ m⁻² and decreased at lower temperatures and lower value of water vapor concentration. Predicted growth rates were mostly slightly higher.Benzene, toluene, ethylbenzene, and xylenes (BTEX) were not detected in ice above their detection limits (DLs) of 25 pg g_ice⁻¹ (toluene, ethylbenzene, xylenes) and 125 pg g_ice⁻¹ (benzene) over the entire temperature range. Median concentrations of n-propylbenzene, 4-ethyltoluene, 1,3,5-TMB, tert.-butylbenzene, 1,2,4-TMB, and 1,2,3-TMB were between 4 and 176 pg g_ice⁻¹ at gas concentrations of 10.3–10.7 μg m⁻³ calculated at 295 K. Uptake coefficients (K) defined as the product of concentration of AH in ice and density of ice related to the product of their concentration in the gas phase and ice mass varied between 0.40 and 10.23. K increased with decreasing temperatures. Values of Gibbs energy (ΔG) were between −4.5 and 2.4 kJ mol⁻¹ and decreased as temperatures were lowered. From the uptake experiments, the uptake enthalpy (ΔH) could be determined between −70.6 and −33.9 kJ mol⁻¹. The uptake entropy (ΔS) was between −281.3 and −126.8 J mol⁻¹ K⁻¹. Values of ΔH and ΔS were rather similar for 4-ethlytoluene, 1,3,5-TMB and tert.-butylbenzene, whereas 1,2,3-TMB showed much higher values.