Environmental photochemistry of PCDDs. Part I. Kinetics and quantum yields of the photodegration of 1,2,3,4,7-penta- and 1,2,3,4,7,8-hexachlorodibenzo-p-dixin in aqueous acetontrile

For the determination of the quantum yields of 1,2,3,4,7-pentachlorodibenzo-$\text{p}$-dioxin ($\text{1}$) and 1,2,3,4,7,8-hexachlorodibenzo-$\text{p}$-dioxin ($\text{2}$), ten Pyrex glass photochemical cells were constructed and their correction factors determined. Quantum yields at 313 nm for $\text{1}$ and $\text{2}$ in aqueous acetonitrile (4:6 v/v) were (9.781 ± 2.376) 10^?5 and (1.096 ± 0.020) × 10^?4, respectively. These quantum yields and the measured absorption spectra were used to estimate the environmental phototransformation first-order rate constants and photochemical half-lives of $\text{1}$ and $\text{2}$ in water under conditions of variable sunlight intensity during various seasons from solar intensity data available in the literature. In summer, typical half-lives for the phototransformation of $\text{1}$ and $\text{2}$, respectively, near the surface of water bodies at 40° north latitude would be 364 ± 88 and 151 ± 3 h; whilst such values in winter would be 1257 ± 309 and 518 ± 10 h.     

Analysis of snake tissue and snake eggs for 2,3,7,8-tetrachlorodibenzo-p-dioxin via fused silica GC combined with atmospheric pressure ionization MS

Several snake tissue samples and one set of snake eggs were collected and analyzed for 2,3,7,8-tetrachlorodibenzo-$\text{p}$-dioxin. The isomer-specific analysis was performed using fused silica GC combined with atmospheric pressure ionization MS. The results ranged from a low of 38 parts-per-trillion (ppt) to high levels over 500 ppt.     

Tetrachlorodibenzo-p-dioxins and tetrachlorodibenzofurans in Atlantic coast striped bass and in selected Hudson River fish,waterfowl and sediments

In striped bass samples from the lower Hudson River and its estuary 2,3,7,8-tetrachlorodibenzo-$\text{p}$-dioxin (2,3,7,8-TCDD) was found at concentrations from 16 to 120 pg/g (ppt). Striped bass from two other locations (Rhode Island coastal waters and Chesapeake Bay, Maryland) had <5 ppt, 2,3,7,8-TCDD. The contaminant, 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF), was found in striped bass from all three locations with concentrations varying from 6 ppt in Chesapeake Bay to 78 ppt in the Hudson River. Results from a limited number of non-migratory fish (carp and goldfish) and sediments suggest that the upper Hudson River is not a source for 2,3,7,8-TCDD/2,3,7,8-TCDF contamination of striped bass.     

Formation of PCDD/Fs from oxidation of 2-monochlorophenol over an Fe2O3/silica surface

The role of iron in surface-mediated formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from 2-chlorophenol (2-MCP) was investigated over the temperature range of 200-550 °C under oxidative conditions. In order to compare and contrast with previous work on copper and ferric oxide-mediated pyrolysis of 2-MCP, identical reaction conditions were maintained (50 ppm 2-MCP, model fly-ash particles containing 5% Fe₂O₃ on silica). Observed products included dibenzo-p-dioxin (DD), 1-monochlorodibenzo-p-dioxin (1-MCDD), dibenzofuran (DF), 4,6-dichlorodibenzofuran (4,6-DCDF), 2,4- and 2,6-dichlorophenol, 2,4,6-trichlorophenol, quinone, catechol, chloro-o-quinone, chlorocatechol and polychlorinated benzenes. Yields of DD and 1-MCDD were 2 and 5 times higher than under pyolysis conditions, respectively. Although 4,6-DCDF was the major PCDD/F product formed with a yield that was 2.5× greater than under pyrolysis, the yield of non-chlorinated DF, which was the dominant PCDD/F product under pyrolysis, decreased by a factor of 3. Furthermore, the ∼2× higher yield of PCDDs under oxidative conditions resulted in a PCDD to PCDF ratio of 0.75 compared to a relatively low ratio of 0.39 previously observed under pyrolytic conditions.     

Soil-catalyzed oxidation of aniline

Aniline partially degraded in sterile soil to azobenzene, azoxybenzene, phenazine, form=anilide, and acetanilide. Nitrobenzene, $\text{p}$-benzoquinone, and unidentified species were possible products; substantial bound residues may also have formed. Soil-catalyzed conversion of aniline or [$\text{d}$₅]aniline seems evidenced by 6-24X more product recovery in sterile soil than in sterile water alone, a process inhibited by Na₂S₂O₄. Freundlich adsorption constants showed: azobenzene > azoxybenzene > phenazine > aniline.     

Changes in the levels of aspartate and alanine aminotransferase activities of Anabastestudineus (Bloch) exposed to disyston

In $\text{Anabas}$$\text{testudineus}$, the per cent changes noted in the aspartate aminotransferase (AAT) activities of gill, brain, intestine, liver, muscle and kidney until 6 hr of exposure to lethal concentration (10.5 mg/L disyston) were relatively much less when compared to those of sublethal concentration (4.0 mg/L disyston). But in the case of alanine aminotransferase (AIAT) activity, the tissues which showed such effect (paradoxical effect) were gill, brain and liver.     

Enumeration of 2,4-D-degrading microorganisms in soils and crop plant rhizospheres using indicator media; high populations associated with sugarcane (Saccharum officinarum)

Population of microorganisms able to degrade 2,4-D (2,4-dichlorophenoxyacetate) were estimated in 4 non-rhizosphere and 5 rhizosphere soils in Natal by a most probable number (MPN) method using 2,4-D-bromocresol purple media to show 2,4-D degradation with the formation of HC1. Confirmation of herbicide degradation in acid 2,4-D tubes was required by subculturing into fresh 2,4-D-and control indicator media. The MPN estimates of 2,4-D-degrading organisms per g of corresponding rhizosphere/control soils were 6100/212 with African clover ($\text{Trifolium africanum}$ L.) soils, and $\text{46400}\text{178}$, $\text{156000}\text{1480}$ and $\text{40700}\text{6170}$ with sugarcane ($\text{Saccharum officinarum}$ L.) soils. The high, stimulated populations of 2,4-D-degrading microorganisms in the sugarcane rhizospheres suggest the possibility of rapid degradaton in the rhizosphere as an additional mechanism for the protection of certain plants against soil-applied herbicides.     

Chlordane compounds residues in Weddell seals (Leptonychotesweddelli) from the Antarctic

Weddell seal samples taken from the Antarctic have been found to be contaminated with chlordane compounds. ΣChlordane ($\text{cis}\text{-chlordane}\text{+}\text{cis}\text{-nonachlor}\text{+}\text{trans}\text{-nonachlor}\text{+}\text{oxychlordane}$) was present in blubber of seals at the range of 12 - 62 ng/g fresh weight. The order of chlordane compound concentrations was $\text{trans}\text{-nonachlor}\text{>}\text{oxychlordane}\text{>}\text{cis}\text{-nonachlor}\text{>}\text{cis}\text{-chlordane}$. Relative aboundance of $\text{cis}$-chlordane in Σchlordane is higher than that in humans. A probable explanation for their occurrence in the Antarctic is an airborne transport.     

Semi-empirical estimation of sorption of hydrophobic pollutants on natural sediments and soils

Methods were developed for estimating the equilibrium sorption behavior of hydrophobic pollutants. At low pollutant concentration (aqueous phase concentration less than half the solubility), sorption isotherms were linear, reversible, and characterized by a partition coefficient, K_p. Partition coefficients normalized to organic carbon, K_OC ($\text{K}{}_{\mathrm{OC}}\text{=}\text{K}{}_{\mathrm{p}}\text{fraction}$ organic carbon), were highly invariant over a set of sediments and soils collected from throughout the nation. Equations for estimating K_OC from water solubility (including crystal energy) and octanol/water partition coefficients were developed. The predictive equations were tested on literature sorption data and found to estimate measured K_OC's generally within a factor of two.     

Bioaccumulation of pentachlorophenol by killifish (Fundulussimilus)

Killifish ($\text{Fundulus}$$\text{similis}$) were exposed in the laboratory to pentachlorophenol (PCP) at concentrations of 57 to 610 μg PCP/L. Bioaccumulation reached a plateau value of about 53 by 168 hrs and remained at this level for at least 72 hrs. One-half the plateau value was reached in about 25 hrs. Following exposure, fish placed in PCP-free aquaria lost PCP rather slowly ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～ 4.7}\text{days}$). The depuration data were suggestive of a pool of PCP which was lost more rapidly ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～ 4.2}\text{hrs}$). The results of this study are compared to similar studies in other species. The bioaccumulation factors measured in this study agree relatively well with those in other marine species, but are lower than reported for fresh water species. Possible reasons for this difference are discussed.     

Effect of fungicidal seed treatments on alfalfa growth and nodulation by Rhizobiummeliloti

A study of the effect of 5 fungicide seed treatments on alfalfa ($\text{Medicago}$$\text{sativa}$ L. var. Vernal) growth and nodulation by $\text{Rhizobium}$$\text{meliloti}$ 102F66 was conducted in a growth chamber. Captan, maneb and thiram exhibited greater toxicity to $\text{R}$. $\text{meliloti}$ and alfalfa plants than that of benomyl and zineb. Recovery of the inhibitory effect was rapid.     

Effects of some pesticides on Rhizobiomjaponicum and on the seed germination and pathogens of soybean

The relative toxicity of 23 pesticides, including 21 fungicides and two pyrethroid insecticides, on $\text{Rhizobium}$$\text{japonicum}$, four soybean pathogens, $\text{Fusarium}$$\text{oxysporum}$, $\text{Phytophthora}$$\text{megasperma}$, $\text{Phytophthora}$$\text{parasitica}$ and $\text{Pythium}$$\text{ultimum}$, and germination of soybean seeds was compared with a highly toxic broad spectrum germicide, HgCl₂ under laboratory conditions.     

Photochemistry and environment. VII- The photohydrolysis of chlorobenzene: Studies of the excited state involved

Chlorobenzene excited in dilute aqueous solution is transformed quantitatively into phenol ($\text{ф= 0.10±0.02}$). This reaction involves a triplet state, since it is quenched by biacetyl and sensitized by ketones. Based on quenching experiments, the lifetime of the lowest triplet of chlorobenzene was measured as 30 ns. From the sensitized phosphorescence of biactyl, the quantum yield of intersystem crossing (S₁→T₁) was found to be 0.6 ±0.1. The photophysical characteristics of chlorobenzene are identical in acetonitrile (). Photosensitization of the photohydrolysis is observed with acetone and acetone D6 in aqueous solution. The quantum yield of the sensitized photohydrolysis is limited to 0.06±0.01. Hexadeuterated acetone appeared to be a more specific photosensitizer than acetone.     

Performance of a Semi-Industrial Scale Gasification Process for the Destruction of Polychlorinated Biphenyls

Abstract

A semi-industrial scale test was conducted to thermally treat mixtures of spent oil and askarels at a concentration of 50,000 ppm and 100,000 ppm of polychlorinated biphenyls (PCBs) under a reductive atmosphere. In average, the dry-basis composition of the synthesis gas (syngas) obtained from the gasification process was: hydrogen 46%, CO 34%, CO₂ 18%, and CH₄ 0.8%. PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (PCDDs/PCDFs) in the gas stream were analyzed by high-resolution gas chromatography (GC)-mass spec-trometry. The coplanar PCBs congeners 77, 105, 118, 156/157, and 167 were detected in the syngas at concentrations <2 ×10^?7 mg/m³ (at 298 K, 1 atm, dry basis, 7% O₂). The chlorine released in the destruction of the PCBs was transformed to hydrogen chloride and separated from the gas by an alkaline wet scrubber. The concentration of PCBs in the water leaving the scrubber was below the detection limit of 0.002 mg/L, whereas the destruction and removal efficiency was >99.9999% for both tests conducted. The concentration of PCDDs/PCDFs in the syngas were 8.1 ×10^?6 ng-toxic equivalent (TEQ)/m³ and 7.1 × 10^?6 ng-TEQ/m³ (at 298 K, 1 atm, dry basis, 7% O₂) for the tests at 50,000 ppm and 100,000 ppm PCBs, respectively. The only PCDD/F congener detected in the gas was the octachloro-dibenzo-p-dioxin, which has a toxic equivalent factor of 0.001. The results obtained for other pollutants (e.g., metals and particulate matter) meet the maximum allowed emission limits according to Mexican, U.S., and European regulations for the thermal treatment of hazardous waste (excluding CO, which is a major component of the syngas, and total hydrocarbons, which mainly represent the presence of CH₄).     

Simple and rapid yeast reporter bioassay for dioxin screening: evaluation of the dioxin-like compounds in industrial and municipal waste incineration plants

The CROMIS AhR kit, a simple and rapid yeast bioassay kit, was developed and used to detect dioxins and dioxin-like compounds in 20 gas and solid samples collected from refuse incineration plants in Japan. The World Health Organization toxic equivalent (WHO-TEQ) values of the samples were also calculated using high-resolution gas chromatography/high--resolution mass spectrometry. The WHO-TEQ values of the samples varied greatly, ranging from 0.0021–6.3 ng/g to 0.00013–16 ng/m³N (normal cubic meter) in the solid and gas samples, respectively. 2,3,4,7,8-Pentachlorodibenzofuran (23478-PeCDF) and 1,2,3,7,8-pentachlorodibenzo-p-dioxin (12378-PeCDD) were the major contributors to the samples’ WHO-TEQ values. The yeast in the bioassay responded to these congeners, and the EC₅₀ values of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2378-TeCDD), 12378-PeCDD, and 2,3,4,7,8-PeCDF were 490, 560, and 590 nM, respectively. The incinerator samples were subjected to the bioassay to obtain 2378-TeCDD equivalent values (CROMIS-TEQ values). The CROMIS-TEQ values of the solid and gas samples ranged from 0.0019 to 5.64 ng/g and from 0.14 to 20 ng/m³N, respectively. The CROMIS-TEQ and WHO-TEQ values displayed good correlations (r ²?=?0.94 and 0.95 in the solid and gas samples, respectively), except for those of the samples with low dioxin concentrations (below the Japanese emission standards). Therefore, the CROMIS AhR kit is a useful tool for the initial screening of samples containing dioxin-like compounds.     

Soluble carbohydrates in bean leaves transformed into oxidant-tolerant tissues by EDU treatment

Improved gas-liquid chromatography techniques were used to evaluate the effects of EDUa on soluble leaf carbohydrates in $\text{Phaseolus vulgaris}$ L. ‘Bush Blue Lake 290’. This snap bean cultivar is normally rather sensitive to 0₃ but becomes highly tolerant when treated systemically with EDU. Less than 24 h is required to induce the resistance. Standardized trifoliate leaves from EDU-treated and control plants were sampled 48 h after treatment. Additional plants were sampled 48 h after treatment. Additional plants were exposed to 0₃ one day after EDU soil application to assess the plant tolerance induced. The optimal dose required to enhance oxidant tolerance was 50 mg/pot.Major sugars in both EDU-treated (0₃-tolerant) and untreated (0₃-sensitive) leaves were glyceraldehyde, erythritol, fructose, glucose and sucrose. $\text{Myo}$-inositol, ribose and arbitol were present in lesser or trace amounts. EDU-treatment resulted in significant increases (35–62%) in all soluble carbohydrates except glyceraldehyde and $\text{myo}$-inositol. Implications relating to plant tolerance, to oxidants and stress-induced senescence are discussed.     

Prevalence of low chlorinated dibenzo-p-dioxin/dibenzofurans in human serum

Mono- to tri-chlorinated dibenzo-p-dioxin/dibenzofurans (DD/Fs) have not been studied as extensively as the 17 toxic 2,3,7,8-substituted congeners. In this study for the first time, mono- to octa-chlorinated DD/Fs were analyzed for seventy one human serum samples collected from incinerator workers as well as residents living near and far from the facility. The mean concentrations of ∑Cl_1–8DD/Fs and 17-toxic congeners were 1890 and 398 pg g^?1 lipid (11.9 TEQ pg g^?1 lipid), respectively. 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD, and 1,2,3,6,7,8-HxCDD were predominant congeners that accounted for more than 78% of the TEQ concentrations. The profile for polychlorinated dibenzo-p-dioxins (PCDDs) was dominated by the most chlorinated congener, OCDD (>58%), while decreasing concentrations with increasing degree of chlorination were seen for polychlorinated dibenzofurans (PCDFs); MoCDFs (>83%) and DiCDFs (>6%). ∑Cl_1–3DD/Fs accounted for 77% of the serum concentrations of ∑Cl_1–8DD/Fs. These findings confirm that human beings are exposed to a large amount of ∑Cl_1–3DD/Fs. Moreover, MoCDFs contributed more than 60% of the ∑Cl_1–8DD/Fs and was highly correlated with ∑Cl_1–8DD/Fs. Thus, 2-MoCDF could be a predictive indicator for ∑Cl_1–8DD/Fs (r_s = 0.96), and the combination of 2-MoCDF and OCDD could explain the 95.9% variation in the serum of ∑Cl_1–8DD/Fs. These results suggest that low chlorinated DD/Fs should be studied extensively until these low chlorinated congeners will have been elucidated for their toxicities.     

The effect of cadmium ion on the growth,photosynthesis, and nitrogenase activity of Anabaenainaequalis

The growth of $\text{Anabaena}$$\text{inaequalis}$ was significantly inhibited by Cd²⁺ concentrations greater than 0.02 ppm (μg/ml) and completely inhibited at 0.06 ppm (Day 12). Cadmium had no significant effect upon the lag phase of growth or the culture doubling time, but caused the retardation phase to arrive sooner. One ppm Cd²⁺ significantly inhibited the rates of both photosynthesis and acetylene reduction, by $\text{A}$. $\text{inaequalis}$, with complete inhibition at 4 and 20 ppm respectively. Cell sensitivity increased directly with exposure time. Cadmium caused some cell lysis of $\text{A}$. $\text{inaequalis}$ and induced an increase in filament length, heterocyst frequency, and a loss of cellular contents from filament apical cells. The cellular abnormalities observed and the fact that toxicity increased with longer exposure times, suggested that metal toxicity resulted from effects of Cd²⁺ taken up by cells rather than Cd²⁺ at the cell surface.