Evaluation of the presence of drugs of abuse in tap waters

A total of seventy samples of drinking water were tested for non-controlled and illicit drugs. Of these, 43 were from Spanish cities, 15 from seven other European countries, three from Japan and nine from seven different Latin American countries. The most frequently detected compounds were caffeine, nicotine, cotinine, cocaine and its metabolite benzoylecgonine, methadone and its metabolite EDDP. The mean concentrations of non-controlled drugs were: for caffeine 50 and 19 ng L⁻¹, in Spanish and worldwide drinking water respectively and for nicotine 13 and 19 ng L⁻¹. Illicit drugs were sparsely present and usually at ultratrace level (<1 ng L⁻¹). For example, cocaine has mean values of 0.4 (Spain) and 0.3 ng L⁻¹ (worldwide), whereas for benzoylecgonine, these mean values were 0.4 and 1.8 ng L⁻¹, respectively. Higher concentrations of benzoylecgonine were found in Latin American samples (up to 15 ng L⁻¹). No opiates were identified in any sample but the presence of methadone and EDDP was frequently detected. Total mean values for EDDP were 0.4 ng L⁻¹ (Spain) and 0.3 ng L⁻¹ (worldwide). Very few samples tested positive for amphetamines, in line with the reactivity of chlorine with these compounds. No cannabinoids, LSD, ketamine, fentanyl and PCP were detected.     

FT-IR product study of the OH-initiated oxidation of DMS in the presence of NOx

The influence of NO_x (NO+NO₂) concentrations on the product distribution of the OH-initiated oxidation of DMS has been studied at room temperature using total NO_x concentrations varying from 0 to ∼1800 ppbv (30–600 ppbv NO₂ and 140–1760 ppbv NO). Clear trends in the formation yields of the products SO₂, COS, MSA, MTF (methyl thiolformate), MSPN (methanesulphonyl peroxynitrate), DMSO and DMSO₂ have been observed with variation in NO_x. The presence of low levels of NO reduces the yields of both MTF and COS to zero. The formation yields of MSA and DMSO₂ increase with increasing NO_x concentration, whereas the yields of DMSO and SO₂ decrease. The following approximate changes in the yield, not corrected for possible loss processes, have been measured for variation of NO_x between 0 and ∼1800 ppbv: DMSO decreases from 20 to 3%S; DMSO₂ increases from 3 to 15%S, SO₂ decreases from 70 to 30%S and MSA increases from 4 to 17%S. Under the experiments conditions NO_x levels of several tens of ppbv are required before a perceptible change is observed in the MSA yield. If applicable to the atmosphere such a situation is only likely to be observed near coastal areas affected by pollution. MSPN (CH₃SO₂O₂NO₂) is observed as an oxidation product in the presence of NO₂ even at low levels (e.g. 60 ppbv). Its possible role as a NO_x reservoir in the troposphere is considered.     

Effects of feed-supplementation and hide-spray application of two sources of tannins on enteric and hide bacteria of feedlot cattle

Pathogenic bacteria attached to the hide or shed in the feces of cattle at slaughter can contaminate carcasses intended to be processed for human consumption. Therefore, new pre-harvest interventions are needed to prevent the carriage and excretion of foodborne pathogens in cattle presented to the processing plant. The objectives of this study were to examine the antimicrobial effects of hydrolysable tannin-rich chestnut and condensed tannin-rich mimosa extracts on bacterial indicators of foodborne pathogens when applied as a hide-intervention and as a feed additive to feedlot cattle. Water (control) or solutions (3 % wt/vol) of chestnut- and mimosa-extract treatments were sprayed (25 mL) at the left costal side of each animal to a 1000 cm² area, divided in four equal quadrants. Hide-swabs samples obtained at pre-, 2-min, 8-h, and 24-h post-spray application were cultured to enumerate Escherichia coli/total coliforms and total aerobic plate counts. In a second experiment, diets supplemented without (controls) or with (1.5 % of diet dry matter) chestnut- or mimosa-extracts were fed during a 42–day experimental feeding period. Weekly fecal samples starting on day 0, and rumen fluid obtained on days 0, 7, 21 or 42 were cultured to enumerate E.coli/total coliforms and Campylobacter. Tannin spray application showed no effect of treatment or post-application-time (P> 0.05) on measured bacterial populations, averaging 1.7/1.8, 1.5/1.6 and 1.5/1.7 (log₁₀ CFU/cm²) for E. coli/total coliforms, and 4.0, 3.4 and 4.2 (log₁₀CFU/cm²) in total aerobes for control, chestnut and mimosa treatments, respectively. Mean (± SEM) ruminal E. coli and total coliform concentrations (log₁₀ CFU/mL) were reduced (P< 0.01) in steers fed chestnut-tannins (3.6 and 3.8 ± 0.1) in comparison with the controls (4.1 and 4.2 ± 0.1). Fecal E. coli concentrations were affected by treatment (P< 0.01), showing the highest values (log₁₀ CFU/g) in fecal contents from mimosa-fed steers compared to controls (5.9 versus 5.6 ± 0.1 SEM, respectively). Total coliforms (log CFU/g) showed the highest values (P< 0.01) in feces from chestnut- and mimosa-fed steers (6.0 and 6.1 ± 0.1 respectively) in comparison with controls (5.7 ± 0.1). Fecal Campylobacter concentrations (log₁₀CFU/g) were affected by treatment (P< 0.05), day (P< 0.001) and their interaction (P< 0.01) with the controls having lower concentrations than chestnut- and mimosa-fed steers (0.4, 1.0, and 0.8 ± 0.3, respectively). It was concluded that under our research conditions, tannins were not effective in decreasing measured bacterial populations on beef cattle hides. Additionally, chestnut tannin reduced E. coli and total coliforms within the rumen but the antimicrobial effect was not maintained in the lower gastrointestinal tract. Further research is necessary to elucidate the possible antimicrobial effects of tannins at site-specific locations of the gastrointestinal tract in beef cattle fed high-grain and high-forage diets.     

Effects of multigenerational exposures of D. magna to environmentally relevant concentrations of pentachlorophenol

The re-emergence of schistosomiasis has given rise to ubiquitous concentrations of the primary control agent pentachlorophenol (PCP) in the environment, especially in the surface waters of China. In this study, the effects of environmentally relevant concentrations of PCP, namely, 0.0002, 0.002, 0.02, 0.2, and 2 μmol/L on survival, age at first reproduction, fecundity, length of mothers, and number of molts of Daphnia magna were studied over three generations. The survival of D. magna exposed to 2 μmol/L was significantly affected in the three generations. Toxic effects were enhanced in later generations. Age at first reproduction of F ₁ and F ₂ D. magna was significantly slower than that of the controls. The total number of offspring per female exposed to concentrations of 0.002 μmol/L or greater was less (23.5 to 67.6, 9.4 to 73.7, and 3.6 to 83.7 %) than that of the controls in the F ₀, F ₁, and F ₂ generations, respectively. The body length of mothers significantly decreased (4.7 to 6.8, 9.6 to 15.1, and 13.3 to 23.2 %) after exposure to 0.002 μmol/L or greater than those of unexposed individuals in the F ₀, F ₁, and F ₂ generations, respectively. Dose–response relationships between concentrations of PCP and length and number of molts of D. magna were observed in the F ₀ to F ₂ generations. PCP concentrations on the surface waters of China caused adverse effects to D. magna, which increased over successive generations. Significant effects were observed in the third generation. The multigenerational studies were more sensitive than the single-generation experiments. Thus, multigenerational exposure may be more predictive of chronic exposure under field conditions.     

Nitrification of centrate from dewatering of anaerobically digested sludge

Nitrification of anaerobically digested sludge centrate was studied in bench-scale suspended growth and fixed film enhanced suspended growth systems at temperatures of 10.5-28.5°C and pH values of 6.0-9.1. Nitrification followed zero-order kinetics in both systems, and ammonia removals in excess of 99% were observed. The temperature dependency of the suspended growth nitrification rate observed under not fully acclimated biomass conditions at pH between 6.8 and 8.5, was expressed as k_T = k₂₀θ^T-20where k₂₀ and θ were found to be 0.34 mg NH₃-N/MLVSS-d and 1.033, respectively. The nitrification rate in the fixed film enhanced suspended growth system involving styrofoam pads ranged from 0.11 to 0.13 mg NH₃-N/mg MLVSS-d at temperatures of 21.5-25°C and pH values of 7.8-8.6. The process contained suspended solids in the range of 10-20 mg/l.     

Assessment of fates of estrogens in wastewater and sludge from various types of wastewater treatment plants

We measured five estrogens in the wastewater samples from the municipal wastewater treatment plants (M-WWTPs), livestock wastewater treatment plants (L-WWTPs), hospital WWTPs (H-WWTPs) and pharmaceutical manufacture WWTPs (P-WWTPs) in Korea. The L-WWTPs showed the highest total concentration (0.195-10.4 μg L⁻¹) of estrogens in the influents, followed by the M-WWTPs (0.028-1.15 μg L⁻¹), H-WWTPs (0.068-0.130 μg L⁻¹) and P-WWTPs (0.015-0.070 μg L⁻¹). Like the influents, the L-WWTPs (0.003-0.729 μg L⁻¹) and the M-WWTPs (0.001-0.299 μg L⁻¹) also showed higher total concentration of estrogens in the effluents than the H-WWTPs (0.002-0.021 μg L⁻¹) and P-WWTPs (0.011 μg L⁻¹ in one sample). The L-WWTPs (37.5-543 μg kg⁻¹, dry weight) showed higher total concentrations in sludge than the M-WWTPs (3.16-444 μg kg⁻¹, dry weight) like the wastewater. The distribution of estrogens in the WWTPs may be affected by their metabolism in the human body, their transition through biological treatment processes, and their usage for livestock growth. Unlike the concentration results, the daily loads of estrogens from the M-WWTPs were the highest, which is related to the high capacities of WWTPs.     

Spatial distribution of wet deposition of nitrogen in South Korea

A method is developed to estimate wet deposition of nitrogen in a 11×14 km (0.125°Lon.×0.125°Lat.) grid scale using the precipitation chemistry monitored data at 10 sites scattered over South Korea supplemented by the routinely available precipitation rate data at 65 sites and the estimated emissions of NO₂ and NH₃ at each precipitation monitoring site. This approach takes into account the contributions of local NO₂ and NH₃ emissions and precipitation rates on wet deposition of nitrogen. Wet deposition of nitrogen estimated by optimum regression equations for NO₃⁻ and NH₄⁺ derived from annual total monitored wet deposition and that of emissions of NO₂ and NH₃ is incorporated to normalize wet deposition of nitrogen at each precipitation rate class, which is divided into 6 classes. The optimum regression equations for the estimation of wet deposition of nitrogen at precipitation monitoring sites are developed using the normalized wet deposition of nitrogen and the precipitation rate at 10 precipitation chemistry monitoring sites. The estimated average annual total wet depositions of NO₃⁻ and NH₄⁺ are found to be 260 and 500 eq ha⁻¹ yr⁻¹ with the maximum values of 400 and 930 eq ha⁻¹ yr⁻¹, respectively. The annual mean total wet deposition of nitrogen is found to be about 760 eq ha⁻¹ yr⁻¹, of which more than 65% is contributed by wet deposition of ammonium while, the emission of NH₃ is about half of that of NO₂, suggesting the importance of NH₃ emission for wet deposition of nitrogen in South Korea.     

Research and application of method of oxygen isotope of inorganic phosphate in Beijing agricultural soils

Phosphorus (P) in agricultural ecosystems is an essential and limited element for plants and microorganisms. However, environmental problems caused by P accumulation as well as by P loss have become more and more serious. Oxygen isotopes of phosphate can trace the sources, migration, and transformation of P in agricultural soils. In order to use the isotopes of phosphate oxygen, appropriate extraction and purification methods for inorganic phosphate from soils are necessary. Here, we combined two different methods to analyze the oxygen isotopic composition of inorganic phosphate (δ¹⁸O_P) from chemical fertilizers and different fractions (Milli-Q water, 0.5 mol L^?1 NaHCO₃ (pH = 8.5), 0.1 mol L^?1 NaOH and 1 mol L^?1 HCl) of agricultural soils from the Beijing area. The δ¹⁸O_P results of the water extracts and NaHCO₃ extracts in most samples were close to the calculated equilibrium value. These phenomena can be explained by rapid P cycling in soils and the influence of chemical fertilizers. The δ¹⁸O_P value of the water extracts and NaHCO₃ extracts in some soil samples below the equilibrium value may be caused by the hydrolysis of organic P fractions mediated by extracellular enzymes. The δ¹⁸O_P values of the NaOH extracts were above the calculated equilibrium value reflecting the balance state between microbial uptake of phosphate and the release of intracellular phosphate back to the soil. The HCl extracts with the lowest δ¹⁸O_P values and highest phosphate concentrations indicated that the HCl fraction was affected by microbial activity. Hence, these δ¹⁸O_p values likely reflected the oxygen isotopic values of the parent materials. The results suggested that phosphate oxygen isotope analyses could be an effective tool in order to trace phosphate sources, transformation processes, and its utilization by microorganisms in agricultural soils.     

Monitoring of environmental contaminants in raw bovine milk and estimates of dietary intakes of children in South Korea

Persistent organic pollutants (POPs) are ubiquitous residual contaminants in the environment and in the food chain. Milk is an important matrix for monitoring POP contamination. This study determined the concentrations of POPs including polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in raw bovine milk, and the data was used to estimate dietary intakes in South Korea. The average concentrations of PBDEs, HCB, PCDD/Fs, and DL-PCBs in raw milk were 0.29 ng g⁻¹ fat, 0.50 ng g⁻¹ fat, 0.27 pg TEQ g⁻¹ fat, and 0.33 pg TEQ g⁻¹ fat, respectively. No significant relationship was found between the concentrations of analytes and the regions sampled. The dietary intakes of PBDEs from the consumption of milk was calculated to be 0.26, 0.10, and 0.05 ng kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. The dietary intakes of HCB was calculated to be 0.44, 0.16, and 0.09 ng kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. The dietary intakes of PCDD/Fs and DL-PCBs was calculated to be 0.78, 0.29, and 0.16 pg TEQ kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. These results indicated that the residual levels of PBDEs, HCB, PCDD/Fs, and DL-PCBs in raw bovine milk were within safe levels.     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Study of size distribution of atmospheric aerosol at Agra

Measurements on size distribution of atmospheric aerosol were made at Dayalbagh, Agra during July to September 1998. A 4-stage cascade particle sampler (CPS - 105) which fractionates particles in sizes ranging between 0.7 and >10.9 μm, was used. Samples were collected on Whatman 41 filters. The filters were analyzed for the major water-soluble ions. The anions (F, Cl, NO₃ and SO₄) were analyzed by Dionex DX-500 ion chromatograph while atomic absorption and colorimetric techniques were used for the analysis of cations (Na, K, Ca and Mg) and NH₄, respectively. The average mass of aerosol was found to be 131.6 μg m⁻³ and aerosol composition was found to be influenced by terrigeneous sources. The mass size distribution of total aerosol and the ions NH₄, Cl, NO₃, K, Ca, Mg, SO₄ and Na was bimodal while that of F was unimodal. SO₄, F, K and NH₄ dominated in the fine mode while Ca, Mg, Cl and NO₃ were in abundance in coarse fraction. Na was found in both coarse as well as fine mode. Coarse mode SO₄ and NO₃ have been ascribed to contribution from re-suspension of soil and formation by heterogeneous oxidation on soil derived particles. Preponderance of K in fine mode is attributed to emissions from vegetation and from burning of plant materials. Ca, Mg, Cl and NO₃ are largely soil derived and hence dominate in coarse fraction. Equivalent ratios of NH₄/(SO₄+NO₃) were calculated for both fine and coarse aerosols. The coarse mode ratio varied between 0.7 and 1.4 while in fine mode it ranged between 1.4 and 1.9. It shows that aerosol is basic, the basicity of coarse mode is due to higher concentration of soil-derived alkaline components while the basicity in fine mode is due to neutralization of acidity by NH₃.     

Oxygen-18 study of high-temperature air oxidation of SO2

The oxygen-18 enrichment in sulfates formed at high temperatures (475–500°C) by platinum-catalyzed air oxidation of SO₂ to SO₃ in humidified air, was found to be several parts per thousand higher than in the air oxygen, SO₂, or water vapor from which the sulfates were formed. Variation of the δ¹⁸O in the sulfates showed little dependence on variation of the δ¹⁸O in the water vapor. The mechanism of sulfate formation involved isotopic exchange between the air oxygen and water vapor, isotopic exchange between the water vapor and SO₂, and formation of the hydrate, H₂SO₄· 3H₂O.When Fe₂O₃ or V₂O₅ was heated in mixtures of air, water vapor, and SO₂, some of the SO₂ was analytically oxidized (via SO₃ formation) to sulfate of relatively high δ¹⁸O and the remainder to chemisorbed sulfate of relatively low δ¹⁸O. Charcoal and fly ash (containing unburned carbon and basic oxides) reacted with the SO₂ to yield chemisorbed sulfates of relatively low δ¹⁸O.     

Constituents of volatile organic compounds of evaporating essential oil

Essential oils containing aromatic compounds can affect air quality when used indoors. Five typical and popular essential oils—rose, lemon, rosemary, tea tree and lavender—were investigated in terms of composition, thermal characteristics, volatile organic compound (VOC) constituents, and emission factors. The activation energy was 6.3–8.6 kcal mol^?1, the reaction order was in the range of 0.6–0.8, and the frequency factor was 0.01–0.24 min^?1. Toluene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, n-undecane, p-diethylbenzene and m-diethylbenzene were the predominant VOCs of evaporating gas of essential oils at 40 °C. In addition, n-undecane, p-diethylbenzene, 1,2,4-trimethylbenzene, m-diethylbenzene, and 1,2,3-trimethylbenzene revealed high emission factors during the thermogravimetric (TG) analysis procedures. The sequence of the emission factors of 52 VOCs (137–173 mg g^?1) was rose ≈ rosemary > tea tree ≈ lemon ≈ lavender. The VOC group fraction of the emission factor of aromatics was 62–78%, paraffins were 21–37% and olefins were less than 1.5% during the TG process. Some unhealthy VOCs such as benzene and toluene were measured at low temperature; they reveal the potential effect on indoor air quality and human health.     

Measurement and modeling of the dry deposition of peroxides

easurements of the dry deposition velocity (V_d) of hydrogen peroxide (H₂O₂) and total organic peroxides (ROOH) were made during four experiments at three forested sites. Details and uncertainties associated with the measurement of peroxide fluxes by the flux-gradient method are discussed. The results are compared to those predicted using a bulk-resistance model of the type commonly used in regional photochemical models. Good agreement between the H₂O₂ V_d measurements and a bulk resistance model is obtained when the model contains a zero surface resistance (R_c) and a common form for the laminar leaf-layer resistance (R_b) based on Schmidt and Prandtl numbers. In this case, a near-zero (<5 s m^-1) surface resistance is confirmed for H₂O₂ within experimental uncertainties. Surface resistances for ROOH were determined to be about 10–15 s m^-1 over a coniferous forest and 20–40 s m^-1 over a deciduous forest. Higher uncertainties for ROOH prevent a detailed analysis of the differences in R_c among forest types. However, the ratio of deposition velocities (ROOH/H₂O₂), computed from normalized concentration gradients, ranged from 0.28 to 0.61 (geometric mean) at the three sites. Differences in molecular diffusivities between H₂O₂ and ROOH can only account for an estimated 16% difference in V_d. Thus, the major constituent of ROOH must also be less soluble and/or less reactive than H₂O₂, which is consistent with the characteristics of methylhydroperoxide (MHP).     

Effect of forest edges on deposition of radioactive aerosols

The possible enhancement of aerosol deposition at forest edges was investigated in a wind tunnel and in the field. The wind tunnel study was carried out using 0.82 μm mass median aerodynamic diameter uranium particles and a composite canopy of rye grass and spruce saplings. The field study was undertaken at a coniferous woodland near to BNFL Sellafield, Cumbria, UK. Two transects were set through the woodland to determine the influence of the forest edge on atmospheric deposition of radionuclides released under authorisation from the Sellafield site. Results from the wind tunnel study showed that the deposition flux of uranium particles decreased with distance downwind from the grass–tree edge towards the interior of the canopy. The deposition flux at the edge was maximal at about 4×10⁻⁷ μg of U cm⁻² s⁻¹. This was 3 times higher than that observed over grass where a constant flux of about 1.32×10⁻⁷ μg of U cm⁻² s⁻¹ occurred. Results from the field study showed a clear influence of the forest edge on the atmospheric deposition of ²⁴¹Am and ¹³⁷Cs. Activity depositions of around 4750 and 230 Bqm⁻² for ¹³⁷Cs and ²⁴¹Am, respectively, were measured in front of the woodland. Activity deposition inside the forest edge, however, rose to levels of between 20,200 and 50,900 Bq m⁻² and 1100 and 3200 Bq m⁻² for ¹³⁷Cs and ²⁴¹Am, respectively, depending upon the transect. Similar activity concentrations were measured in the pasture to the front and behind Lady Wood. Results from these studies corroborate those obtained from various studies on air pollutants including radionuclides. This underlines the importance of deposition at the edge of forests and its contribution to the overall canopy deposition. The edge effect is therefore an important factor that should be considered in the assessment of fallout impact, whether this is to be made by either direct sampling or by modelling.     

Seasonal dependence of the oxidation capacity of the city of Santiago de Chile

The oxidation capacity of the highly polluted urban area of Santiago de Chile has been evaluated during a winter measurement campaign from May 25 to June 07, 2005, with the results compared and contrasted with those previously evaluated during a summer campaign from March 8 to 20, 2005. The OH radical budget was evaluated in both campaigns employing a simple quasi-photostationary state model (PSS) constrained with simultaneous measurements of HONO, HCHO, O₃, NO, NO₂, j(O¹D), j(NO₂), 13 alkenes and meteorological parameters. In addition, a zero dimensional photochemical box model based on the Master Chemical Mechanism (MCMv3.1) has been used for the analysis of the radical budgets and concentrations of OH, HO₂ and RO₂. Besides the above parameters, the MCM model has been constrained by the measured CO and other volatile organic compounds (VOCs) including alkanes and aromatics. Total production and destruction rates of OH and HO₂ in winter are about two times lower than that during summer. Simulated OH levels by both PSS and MCM models are similar during the daytime for both winter and summer indicating that the primary OH sources and sinks included in the simple PSS model are predominant. On a 24 h basis, HONO photolysis was shown to be the most important primary OH radical source comprising 81% and 52% of the OH initiation rate during winter and summer, respectively followed by alkene ozonolysis (12.5% and 29%), photolysis of HCHO (6.1% and 15%), and photolysis of O₃ (<1% and 4%), respectively. During both winter and summer, there was a balance between the OH secondary production (HO₂ + NO) and destruction (OH + VOCs) showing that initiation sources of RO₂ and HO₂ are no net OH initiation sources. This result was found to be fulfilled also for all other studies investigated. Seasonal impacts on the radical budgets are also discussed.     

Measurements of the chemical composition of stratiform clouds

Measurements are reported of the chemical composition of the liquid water and interstitial air in warm (> 0°C), non-precipitating stratus and strato-cumulus clouds at various locations in the eastern United States. Inorganic ionic composition of the cloud water was generally dominated by H⁺, NH₄⁺, NO₃⁻ and SO₄²⁻, similar to the composition of precipitation in this region of the U.S. Concentrations of the corresponding interstitial aerosol species and gaseous HNO₃ were invariably low in comparison to concentrations of the respective ionic species in cloudwater. In contrast, the concentration of NO_x (i.e. NO + NO₂ + organic nitrates) was invariably comparable to or in excess of that of cloudwater nitrate. Sulfur dioxide was found at varying concentrations relative to cloudwater sulfate. In many cases, the SO₂ concentration was quite low (< 0.2 ppb) even in the presence of substantial quantities of cloudwater SO₄²⁻ (> 1 ppb equivalent gas-phase concentration), suggesting large fractional conversion and incorporation into cloudwater. In other cases, in which dilute SO₂ plumes (pso, > 5 ppb) were observed in the cloud interstitial air, the gaseous SO₂ concentration substantially exceeded the cloudwater sulfate concentration.Concentrations of H₂O₂ in cloudwater were found to exhibit strong inverse correlation with interstitial SO₂. Appreciable concentrations of SO₂ in cloud interstitial air and H₂O₂ in cloudwater were only rarely observed to coexist, for the most part only one or the other being present above the limit of detection. These observations are consistent with aqueous-phase oxidation of SO₂ by H₂O₂, as has been inferred previously on the basis of laboratory kinetic studies, and with the hypothesis that depending on relative concentrations, either of these species can be a limiting reagent for in-cloud SO₂ oxidation. The uptake of NO_x as cloudwater nitrate is less complete than the uptake of SO₂ as sulfate, and evidence for the occurrence of similar in-cloud processes causing the conversion of NO or NO₂ to cloudwater nitrate has not been found.     

Assessment of microbial contamination within working environments of different types of composting plants

The objective of the study was to determine the degree of microbiological contamination, type of microflora, bioaerosol particle size distribution, and concentration of endotoxins in dust in different types of composting plants. In addition, this study provides a list of indicator microorganisms that pose a biological threat in composting facilities, based on their prevalence within the workplace, source of isolation, and health hazards. We undertook microbiological analysis of the air, work surfaces, and compost, and assessed the particle size distribution of bioaerosols using a six-stage Andersen sampler. Endotoxins were determined using gas chromatography–mass spectrometry (GC-MS). Microbial identification was undertaken both microscopically and using biochemical tests. The predominant bacterial and fungal species were identified using 16S rRNA and ITS1/2 analysis, respectively.?The number of mesophilic microorganisms in composting plants amounted to 6.9 × 10²–2.5 × 10⁴ CFU/m³ in the air, 2.9 × 10²–3.3 × 10³ CFU/100 cm² on surfaces, and 2.2 × 10⁵–2.4 × 10⁷ CFU/g in compost. Qualitative analysis revealed 75 microbial strains in composting plants, with filamentous fungi being the largest group of microorganisms, accounting for as many as 38 isolates. The total amount of endotoxins was 0.0062–0.0140 nmol/mg of dust. The dust fraction with aerodynamic particle diameter of 0.65–1.1 μm accounted for 28–39% of bacterial aerosols and 4–13% of fungal aerosols. We propose the following strains as indicators of harmful biological agent contamination: Bacillus cereus, Aspergillus fumigatus, Cladosporium cladosporioides, C. herbarum, Mucor hiemalis, and Rhizopus oryzae for both types of composting plants, and Bacillus pumilus, Mucor fragilis, Penicillium svalbardense, and P. crustosum for green waste composting plants. The biological hazards posed within these plants are due to the presence of potentially pathogenic microorganisms and the inhalation of respirable bioaerosol. Depending on the type of microorganism, these hazards may be aggravated or reduced after cleaning procedures.

Implications:?This study assessed the microbial contamination in two categories of composting plants: (1) facilities producing substrates for industrial cultivation of button mushrooms, and (2) facilities for processing biodegradable waste. Both workplaces showed potentially pathogenic microorganisms, respirable bioaerosol, and endotoxin. These results are useful to determine the procedures to control harmful biological agents, and to disinfect workplaces in composting plants.