QSPR prediction of chromatographic retention times of pesticides: Partition and fractal indices

The high‐performance liquid‐chromatographic retentions of red‐wine pesticide residues are modeled by structure–property relationships. The effect of different types of features is analyzed: geometric, lipophilic, etc. The properties are fractal dimensions, partition coefficient, etc., in linear and nonlinear correlation models. Biological plastic evolution is an evolutionary perspective conjugating the effect of acquired characters and relations that emerge among the principles of evolutionary indeterminacy, morphological determination and natural selection. It is applied to design the co‐ordination index that is used to characterize pesticide retentions. The parameters used to calculate the co‐ordination index are the molar formation enthalpy, molecular weight and surface area. The morphological and co‐ordination indices barely improve the correlations. The fractal dimension averaged for non?buried atoms, partition coefficient, etc. distinguishes the pesticide molecular structures. The structural and constituent classification is based on nonplanarity, and the number of cycles, and O, S, N and Cl atoms. Different behavior depends on the number of cycles.     

不同泥龄MBR中溶解性微生物代谢产物对膜污染的影响

通过4套平行运行的小试膜生物反应器(membrane bioreactor,MBR)研究了不同泥龄下溶解性微生物代谢产物(soluble microbial products,SMP)对膜污染的影响.以多糖、蛋白质表征SMP的含量,并通过三维荧光光谱(EEM)、分子量分布(MW)、红外光谱(FTIR)及扫面电镜-能谱分析(SEM-EDX)技术分析了不同泥龄下SMP的变化.结果表明,各泥龄MBR对氨氮和COD均有较好的去除效果,但SMP的含量以及膜污染程度均随着泥龄的升高而降低.泥龄越低,膜阻力越大,小分子量物质(< 1 000)积累程度越大,低泥龄MBR中蛋白质以及腐殖酸类物质含量较高;扫描电镜-能谱分析(SEM-DEX)结果表明,金属元素更容易在低泥龄MBR中的膜表面堆积.     

Ozonolysis of monoterpenes in mechanical ventilation systems

In this investigation the ozonolysis of of three monoterpenes (α-pinene, Δ³-carene and limonene) was studied was studied in authentic mechanical ventilation systems, that included either a cross flow or a rotary heat exchanger. The effects of varying three experimental parameters were investigated: the level of ozone (25 and 75 ppb), the reaction time (25 and 75 s), and the surface area in the ventilation duct (14.8 and 29.5 m²). The initial concentration of each of the monoterpenes was 20 ppb in every experiment, and 1–16% of the α-pinene, <0.5–13% of the Δ³-carene, and <0.5–16% of the limonene reacted. The effects of humidity (g m⁻³) and temperature of the outdoor and supply air, and water losses in the ventilation duct, were also evaluated. Experiments were based on a chemometric statistical design. Comparison of the results to theoretically calculated values showed that theoretical calculations underestimated the amounts that reacted in the ventilation systems by factors of 2–13, depending on the monoterpene and experimental settings.     

HRT对固定床厌氧反应器运行效果的影响

为了考察水力停留时间(HRT)对炭纤维载体固定床厌氧反应器运行效果的影响,在进水COD分别为20 000~25 000 mg/L和40 000~45 000 mg/L2个浓度范围下,研究了不同HRT对反应器运行效果的影响。结果表明,通过HRT的调整,在达到相同有机负荷(OLR)下,进水COD为20 000~25 000 mg/L的COD去除率和产气量,明显比进水COD为40 000~45 000 mg/L的运行效果好;进水COD为20 000~25 000 mg/L,HRT为14 h,相应的OLR为41.09 kgCOD/(m3.d)时,COD去除率仍然维持在68%以上,沼气容积产气率达到14.55 m3/(m3.d)。炭纤维载体固定床厌氧反应器具有较高的COD去除率、产气效率以及抵抗低pH、高负荷冲击的能力,运行过程中没有发生反应器堵塞的现象。     

Assessment of sewage sludge bioremediation at different hydraulic retention times using mixed fungal inoculation by liquid-state bioconversion

Sustainable, environmental friendly, and safe disposal of sewage treatment plant (STP) sludge is a global expectation. Bioremediation performance was examined at different hydraulic retention times (HRT) in 3–10 days and organic loading rates (OLR) at 0.66–7.81 g chemical oxygen demand (COD) per liter per day, with mixed filamentous fungal (Aspergillus niger and Penicillium corylophilum) inoculation by liquid-state bioconversion (LSB) technique as a continuous process in large-scale bioreactor. Encouraging results were monitored in treated sludge by LSB continuous process. The highest removal of total suspended solid (TSS), turbidity, and COD were achieved at 98, 99, and 93 %, respectively, at 10 days HRT compared to control. The minimum volatile suspended solid/suspended solid implies the quality of water, which was recorded 0.59 at 10 days and 0.72 at 3 days of HRT. In treated supernatant with 88 % protein removal at 10 days of HRT indicates a higher magnitude of purification of treated sludge. The specific resistance to filtration (SRF) quantifies the performance of dewaterability; it was recorded minimum 0.049 × 10¹² m kg^?1 at 10 days of HRT, which was equivalent to 97 % decrease of SRF. The lower OLR and higher HRT directly influenced the bioremediation and dewaterability of STP sludge in LSB process. The obtained findings imply encouraging message in continuing treatment of STP sludge, i.e., bioremediation of wastewater for environmental friendly disposal in near future.     

Incidence of chlorinated benzenes and chlorinated ethylenes in Lake Ontario Herring Gulls

Great Lakes Herring Gulls (Larus argentatus) and their eggs have proven to be useful integrators on a lakewide basis of high molecular weight, relatively involatile organochlorine pollutants such as PCRs. A search for relatively volatile organochlorine compounds by GC/MS also revealed the presence of tri- and tetrachloroethylene, and isomers of di-, tri-, tetra-, penta- and hexachlorobenzene in the body lipid of adult Herring Gulls from Lake Ontario. Analysis of pooled eggs from colonies throughout the Great Lakes in 1978 showed that pentachlorobenzene and hexachlorobenzene were ubiquitous contaminants at levels from 14–50 ng/kg and 90–350 ng/kg, respectively. Hexachlorobenzene levels were 2–3 times higher in Lake Ontario than the other lakes, whereas pentachlorobenzene was more evenly distributed geographically. Levels of 1,2,3,4-tetra-, 1,2,4,5-tetra- and 1,2,4-trichlorobenzene near the detection limit of 10–20 ng/kg were found in a few samples.     

Aerosols formed from the chemical reaction of monoterpenes and ozone

Chamber experiments were conducted to study the aerosol products from the ozonolysis of the major atmospheric monoterpenes; α-pinene, β-pinene and limonene. It was found that the α-pinene-O₃ reaction produced mainly 2′, 2′-dimethyl-3′-acetyl cyclobutyl ethanal (pinonaldehyde), the β-pinene-O₃ reaction, mainly 6,6-dimethyl-bicyclo [3.1.1] heptan-2-one and the limonene-O₃ reaction, several unidentified products. These products were sought in forest aerosols and pinonaldehyde was detected in the atmosphere.     

Synthesis of chlorinated dibenzofurans and chlorinated amino-dibenzofurans from the corresponding diphenyl ethers and nitro-diphenylethers

The synthesis of five chlorinated dibenzofurans and three chlorinated animodibenzofurans from easily available diphenyl ethers is described. Also reported is the preparation of the diphenyl ethers. The ¹H-NMR and mass spectra data for the compounds are also reported.     

Photooxidant-forming monoterpenes in air plumes from kraft pulp industries

Monoterpenes emitted to air from two Swedish kraft (sulphate) pulp-mills were determined by sampling on the Tenax adsorbent followed by laboratory analysis using thermal desorption combined with high-resolution gas chromatography. The composition of the terpenes was found to be similar in the emissions from various parts of the process as well as in the mill plume. The bicyclic terpenes alpha-pinene and 3-carene, originating principally from wood of Scots pine (Pinus sylvestris), predominated among the thirteen assessed hydrocarbon monoterpenes. Terpinolene was the most prominent among the particularly reactive terpenes with a lifetime in ozone-rich air of only a few minutes. The rapid formation of photooxidants by chemical reactions of the terpenes with other components of the mill plume is discussed. It is concluded that a variety of phytotoxic photooxidants are formed which may contribute significantly to forest decline within 50 km of mills located along coasts.     

High ambient concentrations of monoterpenes in a Scandinavian pine forest

Total monoterpene levels of the order of 100 μg m ⁻³ were assessed in the summer night air of a typical young planted forest of Scots pine (Pinus silvestris) in Sweden. These concentrations are much higher than those reported in previous studies of ambient monoterpenes. Predominant species were α-pinene and 3-carene. Camphene, β-pinene, myrcene, β-phellandrene and limonene were other prominent components determined. The monoterpenes were shown to originate almost exclusively from Scots pine and the proportions between them to be characteristic of this conifer species.     

Aerosols formed from the chemical reaction of monoterpenes and ozone

Chamber experiments were conducted to study the aerosol products from the ozonolysis of the major atmospheric monoterpenes; α-pinene, β-pinene and limonene. It was found that the α-pinend–O₃ reaction produced mainly 2′. 2′-dimethyl-3′-acetyl cyclobutyl ethanal (pinonaldehyde), the β-pinene–O₃ reaction, mainly 6,6-dimethyl-bicyclo [3.1.1] heptan-2-one and the limonene–O₃ reaction, several unidentified products. These products were sought in forest aerosols and pinonaldehyde was detected in the atmosphere.     

Microbial degradation of chlorinated dioxins

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were introduced into the biosphere on a large scale as by-products from the manufacture of chlorinated phenols and the incineration of wastes. Due to their high toxicity they have been the subject of great public and scientific scrutiny. The evidence in the literature suggests that PCDD/F compounds are subject to biodegradation in the environment as part of the natural chlorine cycle. Lower chlorinated dioxins can be degraded by aerobic bacteria from the genera of Sphingomonas, Pseudomonas and Burkholderia. Most studies have evaluated the cometabolism of monochlorinated dioxins with unsubstituted dioxin as the primary substrate. The degradation is usually initiated by unique angular dioxygenases that attack the ring adjacent to the ether oxygen. Chlorinated dioxins can also be attacked cometabolically under aerobic conditions by white-rot fungi that utilize extracellular lignin degrading peroxidases. Recently, bacteria that can grow on monochlorinated dibenzo-p-dioxins as a sole source of carbon and energy have also been characterized (Pseudomonas veronii). Higher chlorinated dioxins are known to be reductively dechlorinated in anaerobic sediments. Similar to PCB and chlorinated benzenes, halorespiring bacteria from the genus Dehalococcoides are implicated in the dechlorination reactions. Anaerobic sediments have been shown to convert tetrachloro- to octachlorodibenzo-p-dioxins to lower chlorinated dioxins including monochlorinated congeners. Taken as a whole, these findings indicate that biodegradation is likely to contribute to the natural attenuation processes affecting PCDD/F compounds.     

Seasonal variation of monoterpenes in the atmosphere of a pine forest

Seasonal variation of monoterpene concentration in the atmosphere of a pine forest was measured and is discussed in relation to various environmental factors. The concentration of monoterpenes was low in winter, and higher and more variable in summer and autumn. Rough seasonal variation may be explained by temperature differences, but changes from day to day are anticorrelated with ozone concentration. The emission rate of monoterpenes from a pine forest was estimated on the basis of atmospheric concentration, going on the assumption that the disappearance of monoterpenes in the forest is governed by atmospheric reactions.     

Structure-activity relationships of larvicidal monoterpenes and derivatives against Aedes aegypti Linn

In the search for larvicidal compounds against Aedes aegypti L. (Diptera: Culicidae), a collection of monoterpenes were selected and evaluated. R- and S-limonene exhibited the highest larvicidal potency (LC₅₀ = 27 and 30 ppm, respectively), followed by γ-terpinene (LC₅₀ = 56 ppm) and RS-carvone (LC₅₀ = 118 ppm). Structural characteristics which may contribute to the understanding of the larvicidal activity of monoterpenes were empirically identified. The presence of heteroatoms in the basic hydrocarbon structure decreases larvicidal potency. Conjugated and exo double bonds appear to increase larvicidal potency. Replacement of double bonds by more reactive epoxides decreases the larvicidal potency. The presence of hydroxyls in the cyclic structure resulted in decreased potency, probably due to increased polarity indicanting that lipophilicity seems to play an important role in increasing the larvicidal potency in this set of compounds.