Preliminary investigation on the environmental occurrence and effects of antibiotics used in aquaculture in Italy

A preliminary investigation has been carried out on the occurrence and effects of antibiotics used in Italian aquaculture with the objective of identifying priorities for monitoring programmes. According to the information available on the most pertinent and diffuse fish diseases and their related therapies, the presence of flumequine and oxytetracycline in sediments sampled from two trout farms and three sea-bass farms and in their surrounding environments was selected for an analytical investigation. The concentrations of oxytetracycline and flumequine varied up to a maximum of 246.3 and 578.8 microg/kg d.w., respectively. Flumequine was seen to have the highest toxicity in a bioluminescence assay with EC50 values varying within the range of 12-15 mg/l, while the EC50 values for oxytetracycline were within the range of 121-139 mg/l. The results of the present study indicate flumequine and oxytetracycline as priority chemicals to be monitored for possible environmental side effects of aquaculture in Italy. Apart from peak concentrations the chronic presence of flumequine and oxytetracycline in sediments both inside and outside farms should also be considered. In spite of the potential risks related to the use of antibiotics, the concentrations found in the sediments of the studied fish farms are significantly lower than those found in other areas.     

Metabolism of the nonylphenol isomer [ring-U-14C]-4-(3',5'-dimethyl-3'-heptyl)-phenol by cell suspension cultures of Agrostemma githago and soybean

The biotransformation of the nonylphenol isomer [ring-U-14C]-4-(3',5'-dimethyl-3'-heptyl)-phenol (4-353-NP, consisting of two diastereomers) was studied in soybean and Agrostemma githago cell suspension cultures. With the A. githago cells, a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v) was used, in order to produce higher concentrations and amounts of 4-353-NP metabolites for their identification; 4-353-NP was applied via the n-hexadecane phase. Initial concentrations of [14C]-4-353-NP were 1 mg L(-1) (soybean), and 5 and 10 mg L(-1) (A. githago). After 2 (soybean) and 7 days (A. githago) of incubation, the applied 4-353-NP was transformed almost completely by both plant species to four types of products: glycosides of parent 4-353-NP, glycosides of primary 4-353-NP metabolites, nonextractable residues and unknown, possibly polymeric materials detected in the media. The latter two products emerged especially in soybean cultures. Portions of primary metabolites amounted to 19-22% (soybean) and 21-42% of applied 14C (A. githago). After liberation from their glycosides, the primary 4-353-NP metabolites formed by A. githago were isolated by HPLC and examined by GC-EIMS as trimethylsilyl derivatives. In the chromatograms, eight peaks were detected which due to their mass spectra, could be traced back to 4-353-NP. Seven of the compounds were side-chain monohydroxylated 4-353-NP metabolites, while the remaining was a (side-chain) carboxylic acid derivative. Unequivocal identification of the sites of hydroxylation/oxidation of all transformation products was not possible. The main primary metabolites produced by A. githago were supposed to be four diastereomers of 6'-hydroxy-4-353-NP (about 80% of all products identified). It was concluded that plants contribute to the environmental degradation of the xenoestrogen nonylphenol; the toxicological properties of side-chain hydroxylated nonylphenols remain to be examined.     

Metabolism of the Nonylphenol Isomer [Ring-U-14c]-4-(3′,5′-Dimethyl-3′-Heptyl)-Phenol by Cell Suspension Cultures of Agrostemma githago and Soybean

Abstract

The biotransformation of the nonylphenol isomer [ring-U-¹⁴C]-4-(3′,5′-dimethyl-3′-heptyl)-phenol (4-353-NP, consisting of two diastereomers) was studied in soybean and Agrostemma githago cell suspension cultures. With the A. githago cells, a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v) was used, in order to produce higher concentrations and amounts of 4-353-NP metabolites for their identification; 4-353-NP was applied via the n-hexadecane phase. Initial concentrations of [¹⁴C]-4-353-NP were 1 mg L^?1 (soybean), and 5 and 10 mg L^?1 (A. githago). After 2 (soybean) and 7 days (A. githago) of incubation, the applied 4-353-NP was transformed almost completely by both plant species to four types of products: glycosides of parent 4-353-NP, glycosides of primary 4-353-NP metabolites, nonextractable residues and unknown, possibly polymeric materials detected in the media. The latter two products emerged especially in soybean cultures. Portions of primary metabolites amounted to 19–22% (soybean) and 21–42% of applied ¹⁴C (A. githago). After liberation from their glycosides, the primary 4-353-NP metabolites formed by A. githago were isolated by HPLC and examined by GC-EIMS as trimethylsilyl derivatives. In the chromatograms, eight peaks were detected which due to their mass spectra, could be traced back to 4-353-NP. Seven of the compounds were side-chain monohydroxylated 4-353-NP metabolites, while the remaining was a (side-chain) carboxylic acid derivative. Unequivocal identification of the sites of hydroxylation/oxidation of all transformation products was not possible. The main primary metabolites produced by A. githago were supposed to be four diastereomers of 6′-hydroxy-4-353-NP (about 80% of all products identified). It was concluded that plants contribute to the environmental degradation of the xenoestrogen nonylphenol; the toxicological properties of side-chain hydroxylated nonylphenols remain to be examined.     

Structure characterization and thermal stabilities of the isomers of the brominated flame retardant 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane

1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) is used primarily as an additive flame retardant. 1H NMR spectroscopy and an X-ray structure determination have revealed that a technical mixture consists largely of two (of the four possible) diastereomers, rac-(1R,2R)-1,2-dibromo-(4S)-4-((1S)-1,2-dibromoethyl)cyclohexane (alpha-TBECH) and rac-(1R,2R)-1,2-dibromo-(4S)-4-((1R)-1,2-dibromoethyl)cyclohexane (beta-TBECH), in a mole ratio of approximately 1:1. The two other possible isomers, gamma- and delta-TBECH, were not detected in a technical mixture. The TBECH isomers are thermally sensitive and can easily interconvert at temperatures of 125 degrees C. A thermal equilibrium mixture of alpha-, beta-, gamma- and delta-TBECH consists of approximately 33%, 33%, 17% and 17% of these isomers, respectively. Separation of all four TBECH diastereomers, with minimal thermal interconversion of the isomers, was achieved by careful selection of GC-capillary column length and injector temperature. Although technical TBECH does not contain the gamma- and delta-isomers, they may still be relevant environmental contaminants since manufacturing processes utilize thermal processes which may induce their formation.     

Foliar injury, leaf gas exchange and biomass responses of black cherry (Prunus serotina Ehrh.) half-sibling families to ozone exposure

Open pollinated families of black cherry seedlings were studied to determine genotypic differences in foliar ozone injury and leaf gas exchange in 1994 and growth response following three growing seasons. An O(3)-sensitive half-sibling family (R-12) and an O(3)-tolerant half-sibling family (MO-7) planted in natural soil were studied along with generic nursery stock (NS) seedlings. Ozone exposure treatments were provided through open top chambers and consisted of 50, 75, and 97% of ambient ozone, and open plots from May 9 to August 26, 1994. Ambient ozone concentrations reached an hourly peak of 88 ppb with 7-hour averages ranging from 39 to 46 ppb. Seedlings in the 50 and 75% of ambient chambers were never exposed to greater than 80 ppb O(3). Visible foliar ozone injury (stipple) was significantly higher for R-12 seedlings than MO-7 seedlings and increased with increasing ozone exposures. For the chamber treatments averaged over all families, there was no significant difference in stomatal conductance and net photosynthetic rates, but there was a significant decrease in root biomass, and a significant decrease in root/shoot ratio between the 50 and 97% of ambient chambers. Stomatal conductance and net photosynthetic rates were significantly different between families with R-12 seedlings generally greater than MO-7 seedlings. The R-12 seedlings had a 7.5 mmol m(-2) increase in ozone uptake compared to MO-7, and at the same cumulative O(3) exposure R-12 exhibited 40.9% stippled leaf area, whereas MO-7 had 9.2% stippled leaf area. Significant differences were observed in stem volume growth and total final biomass between the open-top chambers and open plots. Although R-12 had the most severe foliar ozone injury, this family had significantly greater stem volume growth and total final biomass than MO-7 and NS seedlings. Root:shoot ratio was not significantly different between MO-7 and R-12 seedlings.     

Adsorption and oxidation of fluoroquinolone antibacterial agents and structurally related amines with goethite

Seven members (ciprofloxacin, enrofloxacin, norfloxacin, ofloxacin, lomefloxacin, pipemidic acid, and flumequine) of the popular fluoroquinolone antibacterial agents (FQs) were found to adsorb strongly to goethite with 50-76% of the added FQ adsorbed under the experimental conditions. The adsorption isotherms fitted well to the Langmuir model. Adsorption was accompanied by slow oxidation of the FQs (except for flumequine) by goethite yielding a range of hydroxylated and dealkylated products. The oxidation kinetics showed different stages in reaction rate, mostly likely caused by accumulation of Fe(II) species on the oxide surface that slowed the reaction. Structurally related amines 1-phenylpiperazine, N-phenylmorpholine, aniline, and N,N-dimethylaniline were found to be oxidized by goethite without significant adsorption. The results strongly indicate that the carboxylic group of FQs is critical for adsorption while the piperazine ring is susceptible to oxidation. A radical mechanism is proposed for the oxidation of FQs by goethite which involves formation of a surface complex between the FQ and surface-bound Fe(III) through adsorption, and initial oxidation at the piperazinyl N1 atom to form radical intermediates that ultimately lead to the final products. This study indicates that Fe oxides in aquatic sediments may well play an important role in the natural attenuation of fluoroquinolone antibacterial agents.     

Structural characterization and thermal stabilities of the isomers of the brominated flame retardant 1,2,5,6-tetrabromocyclooctane (TBCO)

1,2,5,6-Tetrabromocyclooctane (TBCO) is a commercial brominated flame retardant that is employed mainly as an additive in textiles, paints and plastics. Very little is known about its presence or behavior in the environment or its analysis. TBCO can exist as two diastereomers, the stereochemistries of which have not been previously reported. We have named the first eluting isomer, under HPLC conditions, as alpha-TBCO (α-TBCO) and the later eluting isomer as beta-TBCO (β-TBCO) when using an Acquity UPLC BEH C₁₈ column with methanol/acetonitrile/water as the mobile phase. The structural elucidation of these two isomers was accomplished by ¹H NMR spectroscopy, GC/MS, LC/MS and X-ray structure determinations. α-TBCO is (1R,2R,5S,6S)-1,2,5,6-tetrabromocyclooctane and β-TBCO is rac-(1R,2R,5R,6R)-1,2,5,6-tetrabromocyclooctane. As with some other brominated cycloaliphatic compounds, TBCO is thermally labile and the isomers easily interconvert. A thermal equilibrium mixture of α- and β-TBCO consists of approximately 15% and 85% of these isomers, respectively. Separation of the two diastereomers, with minimal thermal interconversion between them, is achievable by careful selection of GC-capillary column length and injector temperature. LC/MS analyses of TBCO also presents an analytical challenge due to poor resolution of the isomers on chromatographic stationary phases, and weak intensity of molecular ions (or major fragment ions) when using LC-ESI/MS. Only bromide ions were seen in the mass spectra. APCI and APPI also failed to produce the molecular ion with sufficient intensity for identification.     

Preparation and X-ray structural characterization of further stereoisomers of 1,2,5,6,9,10-hexabromocyclododecane

Technical 1,2,5,6,9,10-hexabromocyclododecane (HBCD) consists largely of three diastereomers (α-, β-, and γ-HBCD) produced by the trans addition of bromine to cis,trans,trans-cyclododeca-1,5,9-triene (CDT). However, another seven diastereomers are theoretically possible and may be produced by trans addition of bromine across the double bonds of the other three isomers of 1,5,9-CDT. There are indications that small amounts of the minor HBCD isomers may be present in commercial HBCD mixtures or in products containing this brominated flame retardant (BFR). Such minor components may indeed derive from traces of other 1,5,9-CDTs in the cis, trans, trans starting material, however their formation may also be possible through isomerizations during the processing of this BFR or by bioisomerization subsequent to its release into the environment. Two of the seven additional diastereomers (δ- and ε-HBCD) were synthesized previously from trans,trans,trans-CDT. We now report the preparation of the remaining five diastereomers, ζ-, η-, and θ-HBCD from cis,cis,trans-CDT and ι- and κ-HBCD from cis,cis,cis-CDT, and their characterization by ¹H NMR spectroscopy and X-ray crystallography. The availability of these further diastereomers of HBCD should aid in determining if the minor isomers are present in commercial samples of this BFR, in products containing HBCDs, or in environmental samples. We have also carried out an X-ray crystal structure determination on ε-HBCD, so that crystal structures are now available for all 10 HBCD diastereomers.     

Biodegradation of s-triazine herbicide atrazine by Enterobacter cloacae and Burkholderia cepacia sp. from long-term treated sugarcane-cultivated soils in Kenya

In this study soils from sugarcane-cultivated fields were screened for bacterial species capable of atrazine (6-chloro-N²-ethyl-N⁴-isopropyl-1,3,5-triazine-2,4-diamine) degradation due to long exposure of the soils to this herbicide. To enrich for atrazine degraders, Minimal Salt Medium containing atrazine as the sole N source and glucose as the C source was inoculated with soils impacted with this herbicide and incubated. Bacterial growth was monitored by measuring optical density. The degradation of atrazine was followed by measuring residual atrazine in liquid cultures over a given time period by high performance liquid chromatography. Bacterial strains isolated from the enrichment cultures were characterized by biochemical tests and identified by 16S rRNA gene sequencing. Two bacterial strains coded ISL 8 and ISL 15 isolated from two different fields were shown to have 94 and 96% 16S rRNA gene sequence similarity to Burkholderia cepacia respectively. Another bacterial sp., ISL 14 was closely related to Enterobacter cloacae with a 96% 16S rRNA gene sequence similarity. There was not much difference between the extents of atrazine degradation by the enrichment cultures with communities (79–82% applied amount) from which pure strains were isolated and the pure strains themselves in liquid cultures that showed a degradation of 53–83% of applied amount. The study showed existence of bacterial strains in different sugarcane-cultivated fields which can use atrazine as a nitrogen source. The bacterial strains isolated can be used to enhance the degradation of atrazine in contaminated soils where atrazine is still considered to be recalcitrant.     

Synthesis of the two minor isomers, delta- and epsilon-1,2,5,6,9,10-hexabromocyclododecane, present in commercial hexabromocyclododecane

Hexabromocyclododecane (HBCD) is prepared commercially by bromination of cis,trans,trans-cyclododecatriene (ctt-CDT) and widely used as a flame retardant, particularly in polystyrene foams. Commercial HBCD consists largely of three diastereomers, alpha-, beta-, and gamma-HBCD, the structures of which have been known for many years. Recently, the presence in the mixture of small amounts of two minor diastereomers, delta- and epsilon-HBCD, has been reported. Bearing in mind the manner in which commercial HBCD is generated, it was anticipated that these components are probably formed by bromination of trans,trans,trans-cyclododecatriene (ttt-CDT), a common contaminant in commercial ctt-CDT. Indeed, when a sample of ttt-CDT was brominated it gave two products, the NMR spectra and LC/MS and GC/MS behaviour of which confirmed that they are identical to the minor components, delta- and epsilon-HBCD, present in commercial HBCD.     

Determination and health risk assessment of enrofloxacin,flumequine and sulfamethoxazole in imported Pangasius catfish products in Thailand

The goals of this study were to determine the levels of three antibiotics – enrofloxacin, flumequine and sulfamethoxazole – in Pangasius catfish products imported into Thailand and to assess the health risks from consumption. To extract these antibiotic residues, acetonitrile, methanol and a small amount of formic acid were used as solvents. Determination of the antibiotics after extraction steps was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The results showed that 14 and 3 samples of Pangasius catfish products were contaminated with enrofloxacin and sulfamethoxazole, respectively. No flumequine residue was found. While the concentration levels of these antibiotics in most contaminated samples were lower than the European Union (EU) standard, one sample was found to contain sulfamethoxazole at 245.91 µg kg^?1, which was higher than the EU standard (100 µg kg^?1), indicating the likelihood that some contaminated freshwater fish products are widely distributed in Thai markets. Notably, the concentration levels of enrofloxacin in samples of Pangasius catfish with skin were higher than in non-skin products, suggesting that products with skin might retain more antibiotic residues than non-skin products. Although the hazard quotient showed that consuming imported Pangasius catfish products, based on the current consumption rate, will not adversely affect consumer health, antibiotic residues in Pangasius catfish products imported into Thailand should be continually monitored.     

Occurrence,distribution, and risk assessment of antibiotics in the Songhua River in China

The occurrence, distribution, and risk assessment of antibiotics in freshwater systems are receiving global attention, because of their impact on the environment and human health. However, few studies have focused on this topic in Northeast China and its Songhua River, the third-largest river in China. This study investigated the occurrence and distribution of 12 antibiotics, including three cephalosporins (cefazolin, cefmetazole, cefotaxime), three macrolides (azithromycin, clarithromycin, roxithromycin), three fluoroquinolones (ofloxacin, norfloxacin, flumequine), and three sulfonamides (sulfadiazine, sulfapyridine, sulfamethoxazole) in the mainstream and tributaries of the Songhua River. A total of 152 surface water samples were collected in January, May, July, and October 2016. These samples were analyzed using solid-phase extraction (SPE) and ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The results indicated the wide use of all 12 antibiotics in the mainstream of the Songhua River. Sulfamethoxazole and cefazolin were the dominant antibiotics, with maximum concentrations of 73.1 and 65.4 ng L^?1, respectively. Other antibiotics were present at mean concentrations below 15 ng L^?1, except cefmetazole, present at a mean concentration of 35.6 ng L^?1. The spatial distribution of antibiotics showed that unbalanced regional development may lead to the distribution pattern of the antibiotics in the tributaries and the mainstream. Thus study also assessed the seasonal variation of antibiotics in urban surface water; cephalosporin, sulfonamide, fluoroquinolone, and macrolide concentrations were significantly higher during the icebound season than during non-icebound season. This may be due to the low temperature and water flow of the river in winter. Risk assessment showed that azithromycin, clarithromycin, roxithromycin, flumequine, and sulfamethoxazole posed a low or median risk to the aquatic organisms in the mainstream. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River.

     

Biodegradation of endosulfan-contaminated soil in a pilot-scale reactor-bioaugmented with mixed bacterial culture

A novel mixed bacterial culture was enriched from an endosulfan (6, 7, 8, 9, 10, 10 – hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 3, 4-benzo (e) dioxathiepin-3-oxide) processing industrial surface soil. The cultures were successful in the degradation of aqueous phase endosulfan in both aerobic and anaerobic conditions. Using the cultures, endosulfan degradation in silty gravel with sand (GM) was examined via pilot scale reactor at an endosulfan concentration of 0.78 ± 0.01 mg g^{? 1} of soil, and optimized moisture content of 40 ± 1%. During operation, vertical spatial variability in endosulfan degradation was observed within the reactor. At the end of 56 days, maximum endosulfan degradation efficiency of 78 ± 0.2% and 86.91 ± 0.2% was observed in the top and bottom portion of the reactor, respectively. Both aerobic and anaerobic conditions were observed within the reactor. However, endosulfan degradation was predominant in anaerobic condition and the total protein concentration in the reactor was declined progressively down the soil depth. Throughout the study, no known intermediate metabolites of endosulfan reported by previous researchers were observed.     

Determination of levels of polychlorinated biphenyl in transformers oil from some selected transformers in parts of the Greater Accra Region of Ghana

Although polychlorinated biphenyls have never been manufactured in Ghana, it has been used extensively as dielectric fluid in electric transformers and capacitors. However, very little is known of its health and environmental impacts by both managers of these transformers and capacitors and also the general public. This work therefore seeks to explore INAA as a possible alternative to screening transformer oils for PCBs by determining the total chlorine content. The total chlorine content of transformer oil samples from Ghana that tested positive and some randomly selected samples that tested negative from screening using CLOR-N-OIL test kits, have had their total chlorine estimated. INAA using the Research Reactor located at the Ghana Atomic Energy Commission was used to estimate the total chlorine content of the oil samples. Neutron Activation and gamma ray spectroscopy using HPGe detector coupled to MAESTRO 32 software was used to determine the total chlorine content by integrating the peak area of the spectrum into a simplified program that was developed from the activation equation. Instrumental Neutron Activation Analysis was able to validate the result obtained from the test kits screening with accuracy 7.5%.The minimum total chlorine content of the positive samples determined by NAA was 71.34 μg g⁻¹.     

Chlorometabolite production by the ecologically important white rot fungus Bjerkandera adusta.

Two strains of the basidiomycete, Bjerkandera adusta (DAOM 215869 and BOS55) produce in static liquid culture, phenyl, veratryl, anisyl and chloroanisyl metabolites (CAM's) (alcohols, acids and aldehydes) as well as a series of compounds not previously known to be produced by Bjerkandera species: 1-phenyl, 1-anisyl, 1-(3-chloro-4-methoxy) and 1-(3,5-dichloro-4-methoxy) propan-1,2-diols, predominantly as erythro diastereomers with IR, 2S absolute configurations. 1-Anisyl-propan-1,2-diol and 1-(3,5-dichloro-4-methoxy)-propan-1,2-diol are new metabolites for which the names Bjerkanderol A and B, respectively, are proposed. Experiments with static liquid cultures supplied with 13C6- and 13C9-L-phenylalanine showed that all identified aromatic compounds (with the exception of phenol) can be derived from L-phenylalanine. For the aryl propane diols, the 13C label appeared only in the phenyl ring and the benzylic carbon, suggesting a stereoselective re-synthesis from a C7 and a C2-unit, likely aromatic aldehyde and decarboxylated pyruvate, respectively. Other compounds newly discovered to be derived from phenylalanine by this white rot fungus include phenylacetaldehyde and phenylpyruvic, phenylacetic, phenyllactic, mandelic and phenyl glyoxylic (benzoyl formic) acids. For both strains, cultures supplied with Na37Cl showed incorporation of 37Cl in all identified chlorometabolites. Veratryl alcohol and the CAM alcohols, which occur in both strains and can be derived from L-phenylalanine (all 13C-labelled), have reported important physiological functions in this white rot fungus. Possible mechanisms for their formation through the newly discovered compounds are discussed.     

Enhanced degradation of benzo[a]pyrene by Mycobacterium sp. in conjunction with green alga

Previous work in this laboratory has confirmed that the bacteria Mycobacterium sp. strain RJGII.135 and Sphingomonas yanoikuyae strain B1 and the green alga Selanastrum capricornutum strain UTEX 1648 degrade benzo[a]pyrene (BaP) to various BaP intermediates. S. capricornutum was first grown with BaP for 4 days. The organic extract of this media was then introduced into separate cultures of strain RJGII.135 and strain B1; separate cultures were grown with BaP for comparison. Cultures grown with BaP and those grown with the algal/BaP extract showed similar mineralization patterns. The quantity of total metabolites formed was greater in bacterial cultures grown with the algal/BaP extract than those grown with BaP alone. For strain RJGII.135, only 27% of the original BaP remained in cultures grown with the algal/BaP extract; 59% remained in cultures grown with BaP. For strain B1, only 6% of the original BaP remained in cultures grown with the algal/BaP extract; 38% remained in cultures grown with BaP. These results indicate that strategies utilizing organisms together may be necessary in being able to degrade large, recalcitrant polycyclic aromatic hydrocarbons (PAHs) such as BaP.     

Persistence of residues in water and sediment op a fresh‐water lake after surface application of technical chlordane

Abstract

A fresh‐water lake, free from detectable pesticide residues before this study, was treated with a commercial formulation of technical chlordane. Water and sediment samples were analysed for chlordane residues 7, 24, 52, 279. and 421 days after treatment. Residues moved rapidly from the water to the lake bottom, supporting earlier results of a laboratory study with other organochlorines.

In water, α‐ and γ‐chlordane concentrations remained proportional to total chlordane concentrations, as determined by total‐peak area measurements of gas‐liquid chronatogrammes. But in bottom sediments, α‐ and γ‐chlordane were more persistent than other constituents of technical chlordane, supporting recent evidence that quantification of technical chlordane residues on the basis of γ‐chlordane quantification only (or that of a‐ and γ‐chlordane only), can lead to incorrect results and that this method, although simple and fast, should no longer be recommended.     

Contribution of Nitrate and Carbonaceous Species to PM2.5 Observed in Canadian Cities

ABSTRACT

At a variety of Canadian monitoring sites, carbonaceous compounds were estimated to account for an average of 50% of fine particle mass. These estimates were determined by subtracting the total fine particle mass associated with inorganic compounds from the total fine mass determined gravimetrically. This approach, which yields an upper limit estimate of the total amount of carbon-related mass was necessary since particulate carbon was not measured in the Canadian National Air Pollution Surveillance (NAPS) network. In this paper, total carbon estimates are evaluated against organic and elemental carbon measurements at locations in the Greater Vancouver area and Toronto. In addition, particle nitrate measurements at seven Canadian locations are used to determine the importance of nitrate relative to total mass and to examine the sampling artifacts due to the loss of particle nitrate from Teflon filters used in the NAPS di-chotomous samplers.

Measurements of organic and elemental carbon indicated that the total carbon estimation approach provides representative estimates of the average contribution by carbonaceous material to the total fine and coarse mass. The average total carbon among all Vancouver area measurements (N = 225) was 4.28 μg m^-3, while the estimated value was 4.34 μg m^-3. There was a larger discrepancy between Toronto total carbon measurements (12.1 μg m^-3) and estimates (8.8 μg m^-3), which is attributed in part to sampling of particles above 10 mm in diameter. However, the R² relating the measurements and estimates was about 0.71 for both areas. Linear regression slopes of 0.98 for Vancouver and 0.78 for Toronto (nonsignificant intercepts) indicate little bias in the Vancouver estimates, but a tendency for underestimation as the observed total carbon concentration increased in Toronto.

Annually, nitrate was responsible for 17% and 12% of the fine mass in the Vancouver area and Ontario, respectively. In contrast, at two rural locations in southern Quebec and Nova Scotia, only 6% of fine mass was associated with nitrate. Due to filter losses, nitrate concentrations determined through the NAPS dichot sampling were much lower than actual concentrations (0.44 μg m^-3 vs. 2.63 μg m^-3). As a result of these losses (attributed mostly to loss during laboratory storage), previous total carbon estimates for the Canadian NAPS sites were likely to have been overestimated on average by about 10%.     

The Release of Methyl Chloride from Biomass Burning in Australia

Abstract

Black carbon (BC) was measured every 5 min for two years (May 1998–May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two aethalometers, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.53 in the first year and 0.35 in the second year.

The main outdoor source of BC was the general regional background, contributing 83–84% of the total during each of the two years. Morning rush hour traffic contributed 8–9% of the total BC. An evening peak in the fall and winter, thought to include contributions from wood burning, was responsible for ~8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16 and 31%, respectively, of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor aethalometer in both years. An artifact associated with the tape advance was noted for the aethalometer, but a correction factor was developed that reduced the associated error by a factor of 2.     

Contributions of flumequine and nitroarenes to the genotoxicity of river and ground waters

The SOS/umuC assay was performed in conjunction with analytical measurements to identify potential genotoxins in river and adjacent ground waters in the Jialu River basin, China. The major genotoxic activities of the river and adjacent ground waters occurred in the same two fractions (F4 and F11) when assayed using the Salmonella typhimurium strain TA1535/pSK1002. This indicates that ground water near the Jialu River was influenced by the river water. LC-MS/MS analysis indicated that flumequine accounted for 86% and 76% of the genotoxicity in fraction F11 of the river and adjacent ground waters, respectively. When HPLC fractions were tested using the strain NM3009, three fractions showed genotoxic activities for river water sample, while no fractions from ground water samples elicited genotoxic activities. The specific response to the strain NM3009 in one fraction compared with the strain TA1535/pSK1002 suggested the presence of nitroarenes. However, we failed to identify the exact nitroarenes when GC-MS analysis was used to analyze nitroarenes which are well detected in air and soil samples in previous papers.