Effect of mixing on reductive dechlorination of persistent organic pollutants by Fe/Pd nanoparticles

Herein, we report the comparison of two different mixing methods for reductive dechlorination of gamma-hexachlorocyclohexane (γ-HCH), aldrin, and p, p'-dichlorodiphenyl-trichloroethane (p, p'-DDT), using iron/palladium (Fe/Pd) bimetallic nanoparticles. A noticeable enhancement of the reaction rate was found when the reductive dechlorination reaction was carried out in an ultrasound bath as compared with a platform shaker. These enhancements could be attributed to (a) the continuous cleaning and chemical activation of the surfaces of nanoscale Fe/Pd bimetallic nanoparticles by the combined chemical and physical effects of acoustic cavitation; and (b) the accelerated mass transport rates of target POPs to the surfaces of the Fe/Pd nanoparticles. Finally, the degradation intermediates and final products were determined by gas chromatography/mass spectrometry (GC/MS) analysis and the plausible degradation pathways for γ-HCH, aldrin, and p, p'-DDT by Fe/Pd bimetallic nanoparticles were proposed. PRACTITIONER POINTS: Exposure to POPs is a resilient global environmental and health issue. Fe/Pd bimetallic nanoparticles demonstrated > 90 % removal of POPs in the first 30 minutes of the reaction via ultrasonic mixing. GC-MS analyses provided verification of POPs degradation intermediates and final products.

Degradation of aldrin and endosulfan in rotary drum and windrow composting

Removal efficiencies, kinetics and degradation pathways of aldrin, endosulfan α and endosulfan β in vegetable waste were evaluated during rotary drum and conventional windrow composting. The highest percentage removal of aldrin, endosulfan α and endosulfan β in rotary drum composting was 86.8, 83.3 and 85.3% respectively, whereas in windrow composting, it was 66.6%, 77.7% and 67.2% respectively. The rate constant of degradation of aldrin, endosulfan α and endosulfan β during rotary drum composting ranged from 0.410-0.778, 0.057-0.076 and 0.009-0.061 day(-1) respectively. The pathways of degradation of these pesticides in composting process were proposed. Metabolites dieldrin and 1 hydroxychlorodene formed during composting of aldrin in the vegetable waste indicated the occurrence of epoxidation reaction and oxidation of bridge carbon of aldrin containing the methylene group. Formation of chloroendic acid and chloroendic anhydride during composting of endosulfan containing vegetable waste support the occurrence of endosulfan sulfate and dehydration reaction respectively.

Distribution and risk assessment of suspected endocrine-disrupting pesticides in creek water of Mumbai, India

The present study deals with the investigation of existing pollution levels and potential ecological risk assessment of endocrine-disrupting organochlorine and organophosphorous pesticide residues in the Vasai Creek water near Mumbai. The average concentration of α- and β-endosulfan (137.75 ng·L(-1)) exceeds the chronic criteria level of α- and β-endosulfan (6.5 ng·L(-1)) set by US EPA for freshwater aquatic organisms. The concentration levels of aldrin (75.31 ng·L(-1)), dieldrin (71.19 ng·L(-1)) and endrin (76.60 ng·L(-1)) was found to exceed the respective criteria levels of <0.13, 65.1, and 61 ng·L(-1) as set by US EPA for protection of freshwater aquatic organisms. In addition, the level of chlorpyrifos (208.77 ng·L(-1)) exceeds the recommended concentration value of <35 ng·L(-1) set by Ministry of Environment of British Colombia. The results of our study give an indication of probable ecotoxicological risk to the marine breeding organisms of creek.

Role of dissolved organic matter in ice photochemistry

In this study, we provide evidence that dissolved organic matter (DOM) plays an important role in indirect photolysis processes in ice, producing reactive oxygen species (ROS) and leading to the efficient photodegradation of a probe hydrophobic organic pollutant, aldrin. Rates of DOM-mediated aldrin loss are between 2 and 56 times faster in ice than in liquid water (depending on DOM source and concentration), likely due to a freeze-concentration effect that occurs when the water freezes, providing a mechanism to concentrate reactive components into smaller, liquid-like regions within or on the ice. Rates of DOM-mediated aldrin loss are also temperature dependent, with higher rates of loss as temperature decreases. This also illustrates the importance of the freeze-concentration effect in altering reaction kinetics for processes occurring in environmental ices. All DOM source types studied were able to mediate aldrin loss, including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isolated by solid phase extraction, indicating the ubiquity of DOM in indirect photochemistry in environmental ices.

Study on effects of temperature, moisture and pH in degradation and degradation kinetics of aldrin, endosulfan, lindane pesticides during full-scale continuous rotary drum composting

Study focused on effects of temperature, moisture and pH on degradation and degradation kinetics of aldrin, endosulfan (α), endosulfan (β) and lindane during vegetable waste composting using full-scale continuous rotary drum composter (FSCRDC). Extraction, concentration and quantification of pesticides were made from waste material at different stages by ultra-sonification, silica gel column and GC-MS analysis. Removal efficiency of aldrin, endosulfan α, endosulfan β and lindane was found 85.67%, 84.95%, 83.20% and 81.36% respectively due to optimum temperature, moisture, pH and enhanced microbial activity. Maximum temperature in inlet zone was found 60-65°C which is most suitable for complex microbial population. After feeding and turning in inlet zone, temperature reduced to 38°C from 60 to 65°C and regained it within 7-8h, and pH reduced to 5.3±0.2 from 7.5±0.3 in 4h and regained it in 10h. Heterotrophic bacteria Bacillus sp., Pseudomonas sp. and Lactobacillus sp. also decreased from 4.4×10(3) to 7.80×10(2)CFU g(-1) in 2 h due to gradual variation in temperature and pH. No significant temperature change was found in middle and outlet zones during feeding and turning. Degradation of pesticides was observed as first order kinetics and half-life of aldrin, endosulfan α, endosulfan β and lindane was reduced to 25.54, 18.43, 18.43 and 27.43 d from 1095, 60, 270 and 160 d respectively. Thus, the observations in contrast of removal and degradation kinetics of organochlorine pesticides residues in vegetable waste though full-scale rotary drum composting proved it the best suited technique.

Photochemical processing of aldrin and dieldrin in frozen aqueous solutions under arctic field conditions

Organochlorine (OC) contaminants are transported to the Polar Regions, where they have the potential to bioaccumulate, presenting a threat to the health of wildlife and indigenous communities. They deposit onto snowpack during winter, and accumulate until spring, when they experience prolonged solar irradiation until snowmelt occurs. Photochemical degradation rates for aldrin and dieldrin, in frozen aqueous solution made from MilliQ water, 500 μM hydrogen peroxide solution or locally-collected melted snow were measured in a field campaign near Barrow, AK, during spring-summer 2008. Significant photoprocessing of both pesticides occurs; the reactions depend on temperature, depth within the snowpack and whether the predominant phase is ice or liquid water. The effect of species present in natural snowpack is comparable to 500 μM hydrogen peroxide, pointing to the potential significance of snowpack-mediated reactions. Aldrin samples frozen at near 0 °C were more reactive than comparable liquid samples, implying that the microenvironments experienced on frozen ice surfaces are an important consideration.

Degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole in soil

BACKGROUND, AIM, AND SCOPE

3-Chlorocarbazole and 3,6-dichlorocarbazole were isolated from Bavarian soils. The stereospecific formation of the isomers of these chlorinated carbazols can be explained by quantum mechanical calculations using the DFT method. It was shown that chlorination of carbazole and 3-chlorocarbazole respectively is preferred via the sigma-complexes 3-chlorocarbazole and 3,6-dichlorocarbazole as the most stable products. The dioxin-like toxicological potential of 3,6-dichlorocarbazole, determined by the Micro-EROD Test, is in the range of some picogram TCDD equivalents per milligram carbazole. The degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole was analysed within a long-term study (57 days) in soil.

MATERIALS AND METHODS

The soil was extracted by ASE (accelerated solvent extraction) and a further clean-up procedure with column chromatography and chromatography with C18-SPE stationary phases. Quantification of 3-chlorocarbazole and 3,6-dichlorocarbazole was performed employing the isotope-dilution method. The samples were measured with high-resolution GC/MS.

RESULTS

The degradation (ln(c/c(0)) vs. time with best-fit line) showed in almost every storage condition a very small degradation (slopes (h(-1)) in -10(-4) range). However, the decay for the controls were two to three times (-28°C) and six times (with sodium azide) higher, than the decrease of 3-chlorocarbazole and 3,6-dichlorocarbazole in the samples of environmental conditions.

DISCUSSION

Especially because of the toxicological potential of 3-chlorocarbazole and 3,6-dichlorocarbazole the proven degradative fate is of large interest. The results show that the analysed carbazoles are not readily degradable in this time period.

CONCLUSIONS

The expected results of exponential decay behaviour could not be proven.

RECOMMENDATION AND PERSPECTIVES

Longer-lasting studies are expected to reveal more accurate half-lives, although it has been shown here, that the compounds are not readily degradable in their native soil environment.

Composition of aldrin, dieldrin, and photodieldrin enantiomers in technical and environmental samples

Aldrin and dieldrin belong to the group of polycyclic chlorinated insecticides that are banned under the Stockholm Convention (POP Convention). Despite the fact that the use of these compounds ceased many years ago, aldrin and, in particular, dieldrin are still present in the environment from former applications, leading occasionally to contamination of agricultural produce and food, particularly Cucurbitaceae. These prochiral compounds have a complex stereochemistry. In the environment, aldrin is rapidly converted to its epoxide, dieldrin. Photolysis is one of the environmental transformation processes reported to be important for the compounds, leading to photoproducts such as photoaldrin and photodieldrin. In contrast to the parent compounds, photoaldrin and photodieldrin are chiral and exist as pairs of enantiomers. Although dieldrin and its metabolites have been extensively reviewed, the chirality of many of its metabolites has so far not been considered. In this study, the composition of technical aldrin and dieldrin from the 1950s and their photoproducts was investigated using both non-enantioselective and enantioselective gas chromatography with detection by several mass spectrometric techniques. Full enantiomer resolution of photodieldrin was achieved using a column with a silylated gamma-cyclodextrin as chiral selector. Photoaldrin, however, showed peak broadening, indicating some marginal resolution of the enantiomers. Whereas photodieldrin was formed as a racemate from both aldrin and dieldrin by natural sunlight, the analysis of environmental and biological samples (soil, biota) indicated its presence mostly with enantiomer compositions clearly differing from 1:1. The presence of photodieldrin in soil, treated more than 40 years ago with aldrin or dieldrin, documents that the photoreaction of dieldrin plays some role in the transformation of the compounds in the environment and that enantioselective biological processes are involved in its further transformation. The preliminary data also indicate that photodieldrin probably is not bioaccumulated more than dieldrin.

Aldrin epoxidation and dihydroisodrin hydroxylation as probes of in vivo and in vitro oxidative metabolic capability of some caterpillars

Comparative biochemical studies are productive means to study factors that limit both beneficial and harmful effects of chemicals. Reactions such as aldrin epoxidation and dihydroisodrin hydroxylation are valuable assays of oxidative metabolism in scientific studies of chemical biology in insects, subhuman primates and other living things. The tissue distribution of activity in caterpillars may have functional significance. Localization of relatively high concentrations of these cytochrome P450 monooxygenases in gut tissue of lepidoptera may represent an important means to minimize absorption of lipophilic foreign chemicals in food. Some polychlorocycloalkanes permit in vivo and in vitro studies owing to their stability, acceptable toxicity and relatively simple pattern of metabolism. In vivo studies to assess the significance of in vitro findings are feasible with substrates such as aldrin, dihydroisodrin (DHI) and oxidative methylenedioxyphenyl inhibitors such as piperonyl butoxide (PBO) or carbon monoxide. Biphasic dose-dependent decreased and increased DHI-OH formation resulted from PBO pretreatment by gut, fat body, head and Malpighian tubule homogenates of cutworms and gut and fat body (the only tissues tested) of cabbage looper Trichplusia ni (Hübner) and black cutworm Agrotis ipsilon (Hüfnagel). The biphasic in vivo responses of caterpillars to PBO are a reminder of the complexity of biochemical and physiological responses of organisms coexposed to chemicals that are classified, often glibly, as toxic substances and metabolic inhibitors and inducers. Knowledge of dose and time relationships demands very careful evaluation in living things in the environment.

Residues of 18 organochlorine pesticides in 30 traditional Chinese medicines

We analyzed 30 different traditional Chinese medicines (TCMs) to determine levels of contamination with organochlorine pesticides (OCPs). We tested for 18 pesticides: benzene hexachloride (BHC, including alpha-BHC, beta-BHC, gamma-BHC, delta-BHC), heptachlor, heptachlor epoxide, tecnazene, pentachloronitrobenzene (PCNB), hexachlorobenzene, aldrin, methyl pentachlorophenyl sulphide (MPCPS), alpha-endosulfan, trans-chlorodane, cis-chlorodane, p,p'-DDE, o,p'-DDT, p,p'-DDD, and p,p'-DDT. The sample extracts were analyzed by GC-ECD. A total of 280 samples of 30 different TCMs were analyzed. Our results showed that 75.8% of samples contained at least one of the above pesticides. The pesticides detected were tecnazene, hexachlorobenzene, PCNB, heptachlor, aldrin, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, p,p'-DDE, o,p'-DDT, p,p'-DDD p,p'-DDT. More than 50% of samples contained alpha-BHC (55.8%) and PCNB (55.8%); hexachlorobenzene was detected in 40.9% of samples, tecnazene in 19.5%, gamma-BHC in 16.7% and p,p'-DDE in 16.0%. Less than 10% of samples contained beta-BHC, delta-BHC, heptachlor, aldrin, o,p'-DDT, p,p'-DDT and p,p'-DDD. None of the 280 samples contained heptachlor epoxide, MPCPS, alpha-endosulfan, trans-chlorodane, or cis-chlorodane. Concentrations of OCPs in four samples exceeded the maximum allowable residue limits (MRLs) specified in the PRC Pharmacopoeia 2005. The results indicate that the most common contaminants among the 280 samples were alpha-BHC, PCNB, hexachlorobenzene, and tecnazene. Our results suggest that contamination of TCMs with OCPs is widespread. The MRLs for other OCPs commonly found in TCMs (e.g. hexachlorobenzene and tecnazene) should be set as quickly as possible, and the MRLs of OCPs in other TCMs should be established.

Studies on photochemical reactions of air pollutants. XV. Photoreactivity of heptachloro-3'-cyclopentenyldioxy heptachloro-2-cyclopentene formed by exposure of hexachlorocyclopentadiene to ultraviolet light in air

Hexachlorocyclopentadiene (HCCP, 1), one of the starting materials in the synthesis of aldrin (3), was found to be able to epoxidize aldrin (3) to give dieldrin (4) when exposed to artificial light at wavelengths longer than 290 nm. In this photochemical reaction, heptachloro-3'-cyclopentenyldioxy heptachloro-2-cyclopentene (2) was isolated as a key intermediate, which appears to be derived from the interaction between the triplet state of photo-excited HCCP (1) and triplet oxygen (3sigma(g)-), but not from that between the ground state of HCCP (1) and singlet oxygen (1delta(g)). The peroxide (2) plays an important role in the formation of dieldrin (4), because it utilized oxygen atom derived from oxygen in air for the epoxidation.

Removal of aldrin, dieldrin, heptachlor, and heptachlor epoxide using activated carbon and/or Pseudomonas fluorescens free cell cultures

Degradation of aldrin (1,2,3,4,10,10-Hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5-8-dimethanonaphthalene), heptachlor (1H-1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methano indene), dieldrin (1aalpha,2beta,2aalpha,3beta,6beta,6aalpha,7beta,7aalpha)-3,4,5,6,9,9-Hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-d-methanonaphtha[2,3-b]oxirene, and heptachlor epoxide (1aalpha, 1bbeta,2alpha,5alpha,5alphabeta,6beta,6aalpha-2,3,4,5,6,7,7-Heptachloro-1a,1b,5,5a,6,6a-hexahydro-2,5-methano-2H-inden[1,2-b]-oxirene) was tested using free cultures of Pseudomonas fluorescens under controlled conditions. Pesticide concentrations were monitored by gas chromatography during 120 h. Percentages of degradation and biodegradation rates (BDR) were calculated. Data showed a trend suggesting a relation between chemical structure and degradability. Degradation kinetics for each pesticide tested showed that the highest degradation rates were found in the first 24 h. Kinetics data were adjusted to an empirical equation in order to predict their behavior, and the correlation coefficients obtained were satisfactory. Gas chromatography/mass spectrometry (GC/MS) analysis of the final extracts allowed the identification of chlordene and monodechlorodieldrin, which have been reported as final metabolite produced in the biodegradation of this kind of compounds. Regarding adsorption of pesticides on activated vegetal carbon, we concluded that removal efficiencies between 95.45 and 97.18% can be reached, depending on the pesticide and the carbon dose applied. The values for K from the Freundlich equation were quite similar for the four pesticides (between 1.0001 and 1.04), whereas the n values were quite different for each pesticide in the following order of affinity: dieldrin > aldrin > heptachlor epoxide > heptachlor. Equilibrium times, very important for scaling up the process, were between 43 min and 1 h, for the heptachlor epoxide and the heptachlor, respectively.

Establishing a chromium-reactor design for measuring δ2H values of solid polyhalogenated compounds using direct elemental analysis and stable isotope ratio mass spectrometry

2H/1H isotope ratios of polyhalogenated compounds were determined by elemental analysis and isotope ratio mass spectrometry (EA-IRMS). Initial measurements with standard EA-IRMS equipment, which used high-temperature pyrolysis to convert the organic compounds into hydrogen, did not achieve significant signals for polychlorinated pesticides and related compounds, presumably due to the formation of HCl instead of hydrogen. To reverse this problematic reaction, a chromium reactor was incorporated into the element analyzer system, which scavenged Cl, forming chromium chloride and releasing hydrogen again in the form of H2. The optimized system therefore allowed the delta2H values of polyhalogenated compounds to be determined. A quality assurance program was developed based on several parameters. (i) Each compound was analyzed using a sequence of five injections, where the first measurement was discarded. (ii) Recovery of H (when calculated relative to acetanilide) had to be >90% for all replicates in a sequence. (iii) All delta-values within a sequence had to vary by less than 10/1000. (iv) Results had to be reproducible on another day with a different sample scheme. Once this reproducibility had been established, variabilities in the delta2H values of organohalogen standards were investigated using the technique. The highest delta2H value of +75/1000 was found for o,p'-DDD, whereas the strongest depletion in deuterium was found for Melipax (-181/1000). The most important results for comparable compounds were as follows. DDT-related compounds gave delta2H values of between +59 and +75/1000 (technical DDT, o,p'- and p,p'-DDD) or in the range of approximately -1/1000, indicative of the different sources/methods of producing this compound. Four HCH isomers from the same supplier showed relatively similar hydrogen isotope distributions, whereas two lindane (gamma-HCH) standards from other sources had 39/1000 less deuterium. This difference is likely due to different purification steps during the isolation of pure lindane from the technical HCH mixture. An even greater difference was observed between the delta2H values of Toxaphene (US product dating from 1978) and Melipax (product from the former East Germany, dating from 1979), which gave delta2H values of -101/1000 and -181/1000, respectively, meaning that both products were easily distinguished via delta2H-IRMS. Fractioning of hydrogen isotopes in the atmospheric water cycle was suggested as one reason for the different values. In this theory, the water (which had different delta2H values depending on where it was taken from) was incorporated during the biosynthesis of camphene, which is the natural product used to produce both products. These results indicate that hydrogen isotope-specific analysis can be a valuable tool for tracing the origins of a compound in certain cases.

[Preparation and characterization of a novel adsorbent made by cellulose acetate]

A novel adsorbent made by cellulose acetate was developed. Preparation method, structure, and adsorbing characterization of the adsorbent were discussed. SEM results showed that the surface of round adsorbent was stable membrane of cellulose acetate, free from obvious cracks, holes, or other defects; while the cross section of the adsorbent was meshy and a lot of cavities were found. The adsorption results of 4 organochlorinated pesticides, such as Dieldrin, Aldrin, Endrin and Heptachlor, show that the adsorbent has higher efficient for organic pollutants, the adsorption rate is about 85% after 12 h. The adsorption rate is faster with the higher lgKow, and the removal efficiency of Heptachlor and Aldrin is up to 99% after 0.5h. The adsorbent can be used to remove persistent organic pollutants effectively.

Drosophila melanogaster CYP6A8, an insect P450 that catalyzes lauric acid (ω-1)-hydroxylation

Only a handful of P450 genes have been functionally characterized from the approximately 90 recently identified in the genome of Drosophila melanogaster. Cyp6a8 encodes a 506-amino acid protein with 53.6% amino acid identity with CYP6A2. CYP6A2 has been shown to catalyze the metabolism of several insecticides including aldrin and heptachlor. CYP6A8 is expressed at many developmental stages as well as in adult life. CYP6A8 was produced in Saccharomyces cerevisiae and enzymatically characterized after catalytic activity was reconstituted with D. melanogaster P450 reductase and NADPH. Although several saturated or non-saturated fatty acids were not metabolized by CYP6A8, lauric acid (C12:0), a short-chain unsaturated fatty acid, was oxidized by CYP6A8 to produce 11-hydroxylauric acid with an apparent V(max) of 25 nmol/min/nmol P450. This is the first report showing that a member of the CYP6 family catalyzes the hydroxylation of lauric acid. Our data open new prospects for the CYP6 P450 enzymes, which could be involved in important physiological functions through fatty acid metabolism.

Degradation of aldrin in adsorbed system using advanced oxidation processes: comparison of the treatment methods

In this study, Fenton, UV/Fenton, UV/H2O2, UV/Fe2+ advanced oxidation processes have been applied for degradation of aldrin adsorbed on Na-montmorillonitte and activated carbon. Aldrin adsorbed on Na-montmorillonitte was degraded more efficiently than that of on activated carbon. For example, in UV/Fenton technique 95% of aldrin was removed from Na-montmorillonitte while 50% degradation was observed on activated carbon. Degradation of aldrin adsorbed on Na-montmorillonitte has also been achieved effectively using UV/Fe2+ technique despite the absence of H2O2. All AOPs but Fenton have been observed nearly equally effective for degradation of aldrin on Na-montmorillonitte sorbent. Fenton reaction exhibited least activity in degradation aldrin adsorbed on Na-montmorillonitte. The experiments with activated carbon sorbent indicated that phenyl groups in activated carbon structure and aldrin molecules exhibited competitive behavior on reaction with OH* radicals. The results of infrared spectroscopy support this assumption. The degradation efficiency of aldrin using activated carbon sorbent was determined in the following order: UV/Fenton > UV/H2O2 > Fenton > UV/Fe2+.

Effects of atmospheric pollution on a Lichenophagous lepidopteran

Terrestrial epiphytic algae were used to absorb atmospheric pollutants and this material was then fed to larvae of a bagmoth to assess the toxicological effects of the pollutants. Samples of algae were amended with pesticides to simulate agricultural spray drift and with vehicle exhaust gases to simulate road traffic emissions. Larval mortality, immobilization, and feeding were used as the toxicological endpoints. Feeding was the most sensitive of these, but clear dose-response relationships were observed with all three endpoints. The effects of atmospheric pollution on an impacted environment were then investigated using these organisms. Algal samples were collected along a transect that included an area of arable farming, a motorway, and a woodland. Feeding was reduced when the larvae were fed algae from the areas proximal to the arable land and to the motorway. It is suggested that pesticide spray drift and vehicle exhaust emissions may have been the causal agents for these effects.

Studies on photochemical reactions of air pollutants. XII. Photochemical epoxidation of aldrin with suspended particulates in air

Suspended particulates collected in Yokohama, Japan over various 24-h periods were found to cause the photochemical epoxidation of aldrin to dieldrin in good yield. trans-Stilbene did not undergo the epoxidation. Upon irradiation of aldrin together with the suspended particulates in quasi-air consisting of 18O2. 100% incorporation of 18O into dieldrin was obtained. Thus, the oxygen atom in dieldrin originated not from the particulates, but from oxygen in air.