Adsorption/thermal desorption-GC/MS for the analysis of pesticides in the atmosphere

An analytical methodology using Automatic Thermal Desorption (ATD) and GC/MS was developed for the determination of the pesticides alachlor, atrazine, captan, formothion, lindane and phosalone in atmospheric samples. This methodology was developed to evaluate the atmospheric contamination by pesticides during treatments and by post-application. Atmospheric samples were collected by using (4 i.d. x 89 mm) stainless steel sampling tubes containing 125 mg of adsorbents at a flow rate of 80 ml min-1. Different types of adsorbents were tested for their ability to efficiently trap pesticides under study: Tenax TA, Carbopack Y, Carbopack B, Carbotrap, Carboxen, Chromosorb 106 and XAD-4. Results of experiment show that Tenax gives the better results for all the pesticides used but the use of the thermal-desorption method, especially for pesticides with low volatility and/or poor thermal stability presents some difficulties. This method was validated by the analysis of the contamination of atmosphere, through volatilization by post-application processes, of atrazine in a parcel of 1 ha.     

Mutagenicity of chloroaniline/lignin metabolites in the salmonella/microsome assay

Abstract

Chloroanilines are constituents of many agrochemicals and have been found to be metabolized to succinic acid conjugates, e.g., succinamides and succinimides. The mutagenic potential of five chloroanilines and their succinamides and succinimide derivatives have been tested with two strains of Salmonella typhimurium (TA98 and TA100) with and without rat hepatic micro‐somal fraction. None of the compounds produced a dose response effect with a two‐fold increase in revertants indicating that these compounds are not mutagens or promutagens in these assays.     

Mutagenicity of chloroaniline/lignin metabolites in the Salmonella/microsome assay

Chloroanilines are constituents of many agrochemicals and have been found to be metabolized to succinic acid conjugates, e.g., succinamides and succinimides. The mutagenic potential of five chloroanilines and their succinamides and succinimide derivatives have been tested with two strains of Salmonella typhimurium (TA98 and TA100) with and without rat hepatic microsomal fraction. None of the compounds produced a dose response effect with a two-fold increase in revertants indicating that these compounds are not mutagens or promutagens in these assays.     

Biotransformation of the fungicide pentachloronitrobenzene by Tetrahymenathermophila

The protozoan, $\text{Tetrahymena}$$\text{thermophila}$, metabolizes pentachloronitrobenzene to several products, including nitrite, pentachlorothioanisole and pentachloroaniline. The latter two metabolites were identified by gas chromatographymass spectrometry. Pentachlorothioanisole may be produced via a glutathione-dependent pathway, and two key enzymes of this pathway, glutathione transferase and thiol S-methyltransferase, have been detected in crude extracts of this microorganism.     

Organochlorine compounds in the liver of cod (Gadusmorhua) in the Northern Baltic

The livers of 53 female cod weighing about 2 kg, caught at three different sites off the Finnish coast, were analyzed for chlorinated hydrocarbons. The average concentrations of PCB-, DDT- and chlordane compounds varied from 2.3 to 5.3, 0.3 to 1.0 and 0.02 to 0.05 mg/kg, respectively.     

Interactions of Trametes versicolor, Coriolopsis rigida and the arbuscular mycorrhizal fungus Glomus deserticola on the copper tolerance of Eucalyptus globulus

The presence of high levels of Cu in soil decreases the shoot and root dry weights of Eucalyptus globulus. However, higher plant tolerance of Cu has been observed in the presence of the arbuscular mycorrhizal (AM) fungus Glomus deserticola. The hyphal length of G. deserticola was sensitive to low Cu concentrations, and the percentage of AM root colonisation and the metabolic activity of the AM fungus were also decreased by Cu. Therefore, a direct effect of Cu on the development of the AM fungus inside and outside the root cannot be ruled out. E. globulus colonised by G. deserticola had higher metal concentrations in the roots and shoots than do non-mycorrhizal plants; however, the absence of a higher root to shoot metal ratio in the mycorrhizal plants (1.70 ± 0.11) indicated that G. deserticola did not play a filtering/sequestering role against Cu. The saprobe fungi Coriolopsis rigida and Trametes versicolor were able to remove Cu ions from the asparagine–glucose growth media. However, plants inoculated with C. rigida and T. versicolor did not accumulate more Cu than non-inoculated controls, and the growth of the plant was not increased in the presence of these fungi. However, C. rigida increased the shoot dry weight, AM root length colonisation, and metabolic mycelial activity of plants colonised with G. deserticola in the presence of Cu; only this saprobe-AM fungus combination increased the tolerance of E. globulus to Cu. Inoculation with G. deserticola and C. rigida increased the E. globulus Cu uptake to levels reached by hyperaccumulative plants.     

原位水解生成的羟基氧化铁凝聚吸附除磷效能与机制简

将不同摩尔比Fe³⁺与OH^-（[Fe³⁺]：[OH^-]=1：0、1：1、1：2和1：3）反应获得原位水解生成的羟基氧化铁（in situ FeO_xH_y）,研究了具有不同水解程度的羟基氧化铁对凝聚吸附除磷效能与机制。研究显示,In situ FeO_xH_y对磷的去除率随铁投量增大而升高,且均在中性pH范围内具有最佳除磷效果;在相同铁投量条件下,磷去除率随着[OH^-]：[Fe³⁺]的升高而降低;当体系碱度较低时（pH<6）,引入OH^-可促进Fe³⁺水解而提高除磷效果。4种羟基氧化铁均可在15 s内可快速吸附磷,且吸附过程符合准二级动力学模型;Freundlich模型均可很好地描述磷在4种羟基氧化铁表面的吸附行为。磷酸盐吸附后,In situ FeO_xH_y表面Zeta电位明显降低,且[Fe³⁺]：[OH^-]为1：0的羟基氧化铁降低最为显著。结合MINITEQ计算软件磷酸盐、铁盐形态分析结果显示,对于碱度较低的体系,通过投加一定量OH^-可促进Fe³⁺水解,进而使得其更易与水中H₂PO₄^-与HPO₄^2-结合,生成具有多核羟基的磷酸铁络合物,进而提高除磷效果。     

Chronic effects of mercuric chloride on the activities of some enzymes in certain tissues of the fresh water murrel, Channapunctatus

Alterations in the activities of some enzymes in the brain, gills, intestine, kidney, liver and muscles have been examined in the fresh water murrel, $\text{Channa}$$\text{punctatus}$, after exposure to a sublethal concentration of mercuric chloride (3 μg/1) for 15, 30 and 60 days. The results revealed that after 15 days of exposure amino acid oxidase activity was elevated in brain and liver and inhibited in intestine. The activity of xanthine oxidase was increased in gills, and inhibited in kidney. Thirty days exposure produced significant inhibition in the activities of malate dehydrogenase in liver, glutamate dehydrogenase in gills and brain, aminoacid oxidase in gills, and xanthine oxidase in liver and intestine. In contrast, glutamate dehydrogenase in intestine, kidney and liver and aminoacid oxidase in brain and liver were elevated. After 60 days of treatment, a decrease in the activity of glucose-6-phosphatase was recorded in gills, intestine, kidney and liver. Hexokinase activity in kidney and liver, and malate dehydrogenase in all the six tissues were inhibited. Glutamate dehydrogenase activity in intestine, kidney and liver remained higher than in control fish. In brain, kidney and liver the activity of aminoacid oxidase was elevated, but in gills the enzyme activity decreased. Xanthine oxidase activity was inhibited in intestine and liver.     

Bioconcentration of trans-chlordane by the midge, Chironomus decorus

The accumulation and transport of the organochlorine pesticide, trans-chlordane, by the midge, Chironomus decorus was examined in a whole life cycle laboratory exposure assay. Larvae were kept in dosed water exposures including food particles from egg stages through adult metamorphosis and were sampled for weight gain and chemical content over the course of the 50 day study. Accumulation of trans-chlordane was related to the amount of contaminant in the larval environment. Concentration of trans-chlordane (ng contaminant/g tissue) in larvae was not significantly different from second through fourth instar stages but depended upon the weight of the larvae. Differences in time to metamorphosis, weight gain and sex ratios occurred among all replicate exposures, including controls, suggesting nongenetic maternal differences, rather than environmental variation caused by chemical exposure. When the larvae metamorphosed, an average of 82.6% of the contaminant was retained in the adults while 11.4% was left behind in the shed exuviae. This study suggests that terrestrial predators feeding on emerging aquatic insects can be exposed to organic pesticides from aquatic environments.     

Summary of the 1991 EPRI/EPA/DOE SO2 Control Symposium

The 1991 SO₂ Control Symposium was held December 3-6, 1991, in Washington, D.C. The symposium, jointly sponsored by the Electric Power Research Institute (EPRI), the U.S. Environmental Protection Agency (EPA), and the U.S. Department of Energy (DOE), focused attention on recent improvements in conventional sulfur dioxide (SO₂) control technologies, emerging processes, and strategies for complying with the Clean Air Act Amendments of 1990. Its purpose was to provide a forum for the exchange of technical and regulatory information on SO₂ control technology. Over 800 representatives of 20 countries from government, academia, flue gas desulfurization (FGD) process suppliers, equipment manufacturers, engineering firms, and utilities attended. In all, 50 U.S. utilities and 10 utilities in other countries were represented. In 11 technical sessions, a diverse group of speakers presented 111 technical papers on development, operation, and commercialization of wet and dry FGD, Clean Coal Technologies, and combined sulfur dioxide/nitrogen oxides (SO₂/NO_x processes.     

Oxidative dealkylation of five phenylurea herbicides by the fungus CunninghamellaechinulataThaxter

Microorganisms isolated from soil degrade phenylurea herbicides via two major pathways: (i) direct hydrolysis by an amidase leading to N,O-dimethylhydroxylamine, CO₂ and aniline¹ and (ii) N-dealkylation, which has been described as the first step in urea herbicide degradation by a variety of organisms including mammals, plants and microbial systems (for a review see reference 2).Until now no attempts have been made to investigate the mechanism of N-demethylation of substituted ureas in soil microorganisms, due to the instability of the N-hydroxymethyl intermediates. This reaction mechanism has only been described in detail in green plants^3–5. As among soil fungi Phycomycetes are known to demethylate phenylurea herbicides^6,7 this study has been made to identify intermediate hydroxymethyl compounds from urea herbicides, when incubated with the fungus $\text{Cunninghamella echinulata Thaxter}$.     

Mercury induced alterations in the intestinal,absorption of nutrients in the fresh water murrel, Channapunctatus

The effect of five concentrations (10 mM, 1 mM, 0.1 mM, 0.01 mM and 0.001 mM) of mercury on the rate of absorption of glucose, fructose, glycine and tryptophan by the intestine of the fresh water murrel $\text{Channa}$$\text{punctatus}$ has been studied. Intestinal absorption of these nutrients was also examined in fish exposed to a sublethal concentration (3 μg/l) of mercury for 15 and 30 days. Significant decrease was recorded in the rate of intestinal absorption of all the four nutrients with higher concentrations (10 mM, 1 mM and 0.1 mM) of mercury. 0.01 mM and 0.001 mM of mercury also reduced the transport rate but it was insignificant, except in case of tryptophan, where 0.01 mM of mercury also produced significant decrease. Exposure of fish by bath to mercury also resulted in significant decrease in the intestinal transport rate of all the four nutrients after 30 days.     

Interaction of higher marine fungi with the herbicide atrazine. III. Adsorption of atrazine to the marine fungus Dendryphiellasalina

The adsorption of the herbicide ¹⁴C-atrazine to the marine fungus $\text{Dendryphiella}$$\text{salina}$ was studied using sodium azide as an inhibitor of active uptake. Adsorption of atrazine (94 ppb) was found to reach equilibrium within six hours. Adsorption as a function of concentration (9.4 to 468 ppb) conformed to the empirically derived Freundlich equation giving a K value of 6.2. Atrazine on the fungal cell surface was easily desorbed by successive artificial seawater washes indicating a relatively loose binding. The ability of the marine fungus $\text{D.}$$\text{salina}$ to remove ¹⁴C-atrazine from an artificial seawater medium suggests an environmental role in the transport and redistribution of atrazine in estuaries.     

Chemical transformation and flux of different forms of arsenic in the carb Carcinusmaenas

The amount of ingested arsenic assimilated and eliminated by the crab appeared to depend on chemical form of arsenic present in the food. Arsenic-74 was translocated rapidly with a high percentage located in hepatopancreas and exoskeleton. The speciation of radioarsenic determined by sequential extraction of experimental food, feces, muscle and hepatopancreas showed that there is no efficient mechanism within the crab which can covert lipid and water soluble arsenic to arsenite and residual arsenic or vice-versa. The biological mechanism in crab selectively and effectively excretes soluble form of arsenite and residual arsenic much more readily than organic arsenic.     

Analysis of the relationship between ambient levels of O3, NO2 and NO as a function of NOx in the UK

Monitoring data from the UK Automatic Urban and Rural Network are used to investigate the relationships between ambient levels of ozone (O₃), nitric oxide (NO) and nitrogen dioxide (NO₂) as a function of NO_x, for levels ranging from those typical of UK rural sites to those observed at polluted urban kerbside sites. Particular emphasis is placed on establishing how the level of ‘oxidant’, OX (taken to be the sum of O₃ and NO₂) varies with the level of NO_x, and therefore to gain some insight into the atmospheric sources of OX, particularly at polluted urban locations. The analyses indicate that the level of OX at a given location is made up of NO_x-independent and NO_x-dependent contributions. The former is effectively a regional contribution which equates to the regional background O₃ level, whereas the latter is effectively a local contribution which correlates with the level of primary pollution. The local oxidant source has probable contributions from (i) direct NO₂ emissions, (ii) the thermal reaction of NO with O₂ at high NO_x, and (iii) common-source emission of species which promote NO to NO₂ conversion. The final category may include nitrous acid (HONO), which appears to be emitted directly in vehicle exhaust, and is potentially photolysed to generate HO_x radicals on a short timescale throughout the year at southern UK latitudes. The analyses also show that the local oxidant source has significant site-to-site variations, and possible reasons for these variations are discussed. Relationships between OX and NO_x, based on annual mean data, and fitted functions describing the relative contributions to OX made by NO₂ and O₃, are used to define expressions which describe the likely variation of annual mean NO₂ as a function of NO_x at 14 urban and suburban sites, and which can take account of possible changes in the regional background of O₃.     

厌氧—交替O/A的序批式膜生物反应器脱氮除磷性能比较

提出一种高效脱氮除磷的新工艺,即厌氧-交替O/A的序批式膜生物反应器.在HRT为8.4 h、交替O/A时间为10min/10 min时,系统氨氮、总氮、总磷的平均去除率分别达到99.57%、89.92%、93.26%.典型周期试验证明.频繁的O/A环境更利于系统高效脱氮除磷,且O/A交替越频繁,系统中反硝化聚磷菌(DPAO)占聚磷菌(PAO)的比例(即缺氧吸磷速率与好氧吸磷速率的比值)越大.当交替O/A时间为10 min/10 min时.系统中DPAO占PAO的比例为70.87%,比交替O/A时间为30 min/30 min时提高了66%.     

Application of GC-MS/MS for the analysis of PCDD/Fs in sewage effluents

The application of high resolution gas chromatography in combination with tandem mass spectrometry in an ion trap was tested to substitute the expensive high resolution mass spectrometry in analysing polychlorinated dibenzo-p-dioxins and furans in sewage effluents. In tandem mass spectrometry, a set of parameters has to be optimised in order to attain the required sensitivity. To the best of our knowledge, this is the first time a method development for analysing PCDD/Fs with GC-MS/MS in an ion trap is described in this detail. Nine parameters are varied, including isolation window, collision induced dissociation (CID) amplitude, CID time, acquisition mass range, broadband amplitude, CID bandwidth, modulation range, filament current and ion trap temperature. This technique can be adapted to other analytes. By this optimisation, limits of detection of 0.01-0.05 ng/l are obtained. With its selectivity and sensitivity, tandem mass spectrometry is a powerful tool for the determination of PCDD/Fs in water samples. 55 sewage effluent samples from Germany were analysed.     

Optimization of the ionization conditions for the trace analysis of PCDD/PCDF with ion trap MS/MS

Commercial ion trap mass spectrometer provides easy-to-operate MS/MS analysis for the determination of PCDD/PCDF. The limit of quantification is appropriately low (0.2 pg for 23478-P5CDF) because all the stages are performed in the trap and sample losses associated with the ion transportation are minimized. However, if excessive ions are injected into the trap, its electrical fields are distorted and an overall reduction in performance arises. Ionization condition is an important parameter as it affects the amount of the total ions produced. If the amount of interfering compounds are negligible, such as standard solution or cleaned-up sample, lower ionization condition (e.g. electron energy: 30 eV, emission current (EC): 150 μA) is preferable. On the contrary, in case excessive interfering ions are coexisting with PCDD/PCDF, such as crude extract or semi-cleaned-up sample, the ionization condition should be high (e.g. electron energy: 90 eV, EC: 350 μA) for the reproductive quantification.