Synergism of MGK-264 and piperonyl butoxide on the toxicity of plant derive molluscicides

The binary mixture of ethanolic extract of powder, hecogenin, tigogenin, seed powder and thymol with synergiats MGK-264 and piperony butoxide in a 1:5 ratio were used against the . It was observed that the toxic effect of these mixtures were time and dose dependent. The binary mixtures of plant molluscicides with synergist were more toxic with respect to the independent toxicity of these plant molluscicides. Maximum synergistic action (10 fold) of MGK-264 and piperonyl butoxide was observed with hecogenin.     

Cadmium accumulation and Cd-binding proteins in marine invertebrates--a radiotracer study

Tissue and subcellular accumulation of cadmium were studied in different tissues of three marine invertebrates (blue mussel Mytilus edulis, the tunicate Ciona intestinalis and the sea star Asterias rubens) using radioactive ¹⁰⁹Cd as a tracer. The organisms were exposed to 0.05, 2 and 50 μg Cd l⁻¹ for 21 days. Quantitative data were obtained by dissecting, weighing and subsequently measuring radioactivity in organs and tissues. Differences between each exposure and each tissue with regard to the amount of radioactivity and metallothionein (MT) content were evaluated. Obvious interspecies differences in Cd accumulation were observed, as well as differences between tissues of the three species. The highest concentrations of Cd in all exposure treatments were found in the hepatopancreas of M. edulis and body wall of A. rubens. Taking all treatments into account, Cd accumulation in the tunic of C. intestinalis was high compared to other tissues from this species. Over 60% of Cd was present in the S50 fraction in all treatments in all three species. Metallothionein levels were increased at the highest Cd-exposure in all species and tissues, except in branchial pharynx of C. intestinalis where the highest MT level was reached following exposure to 2 μg Cd l⁻¹. The most surprising finding was that even the lowest Cd exposure concentration (0.05 μg Cd l⁻¹) caused MT induction in pyloric caeca of A. rubens, but there was no dose-dependent increase in MT at higher exposure levels.     

Analysis of serpentinophytes from north-east of Portugal for trace metal accumulation--relevance to the management of mine environment

In north–east of Portugal, the serpentinized area is about 8000 ha with a characteristic geology and flora. The serpentine plant community and respective soils were analyzed to examine the trace metal budget in different tissues of the plants exhibiting resistance to trace metals. One hundred and thirty five plant species belonging to 39 families and respective soils have been analyzed for total Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Substantial amounts of Ni, Cr, Co and Mn were detected in plant tissues which are listed below: Ni: Alyssum serpyllifolium (38 105); Bromus hordeaceus (1467); Linaria spartea (492); Plantago radicata (140); Lavandula stoechas (118) and Cistus salvifolius (114); Cr: L. spartea (706.7); Ulmus procera (173.4); A. serpyllifolium (129.3); Cistus ladanifer (40.8); L. stoechas (29.5); P. radicata (27.81); Setariopsis verticillata (25.7); Plantago lanceolata (24); Digitalis purpurea (23.4); Logfia minima (23.1); Arenaria querioides (23); Hieracium peleteranum (22.7); Arenaria montana (14.5); Co: A. serpyllifolium (145.1); L. spartea (63.2); P. radicata (10.4); H. peleteranum (7.3); Lepidium heterophyllum (6.9); A. querioides (6.6); C. salvifolius (6.5); C. ladanifer (6.3); L. stoechas (6.1); Anthyllis lotoides (6.1); L. minima (6.1); Euphorbia falcata (5.7) and B. hordeaceus (5.6); Mn: A. serpyllifolium (830); L. spartea (339); L. stoechas (187.1); L. minima (182.7); Castanea sativa (125); Spergula pentandra (124); P. radicata (119); Cytisus striatus (115.4); Quercus pyrenaica (110); Teucrium scorodonia (109.4); Fraxinus vulgaris (109); Anthyllis sampaiana (108); Quercus ilex (108). The significance of serpentine flora, need for conservation of these fragile and environmentally invaluable plant resources for possible use for in situ remediation of metalliferous substrates are presented in this paper.     

Assessment of toxicity of a glyphosate-based formulation using bacterial systems in lake water

A new Aeromonas bioassay is described to assess the potential harmful effects of the glyphosate-based herbicide, Roundup^®, in the Albufera lake, a protected area near Valencia. Viability markers as membrane integrity, culturability and β-galactosidase production of Aeromonas caviae were studied to determine the influence of the herbicide in the bacterial cells. Data from the multifactor analysis of variance test showed no significant differences (P > 0.05) between A. caviae counts of viability markers at the studied concentrations (0, 50 and 100 mg l⁻¹ of glyphosate).

The effects of Roundup^® on microbial biota present in the lake were assessed by measuring the number of indigenous mesophilic Aeromonas in presence of different amounts of the herbicide at 0, 50 and 100 mg l⁻¹ of glyphosate. In samples containing 50 and 100 mg l⁻¹ of glyphosate a significant (P < 0.05) increase in Aeromonas spp. counts and accompanying flora was observed.

The acute toxicity of Roundup^® and of Roundup^® diluted with Albufera lake water to Microtox^® luminescent bacterium (Vibrio fischeri) also was determined. The EC₅₀ values obtained were 36.4 mg l⁻¹ and 64.0 mg l⁻¹ of glyphosate respectively. The acidity (pH 4.5) of the herbicide formulation was the responsible of the observed toxicity.     

Contaminated sediments and bioassay responses of three macroinvertebrates, the midge larva Chironomus riparius, the water louse Asellus aquaticus and the mayfly nymph Ephoron virgo

Bioassays are widely used to estimate ecological risks of contaminated sediments. We compared the results of three whole sediment bioassays, using the midge larva Chironomus riparius, the water louse Asellus aquaticus, and the mayfly nymph Ephoron virgo. We used sediments from sixteen locations in the Dutch Rhine-Meuse Delta that differed in level of contamination. Previously developed protocols for each bioassay were followed, which differed in sediment pretreatment, replication, and food availability. The Chironomus bioassay was conducted in situ, whereas the other two were conducted in the laboratory. The measured endpoints, survival and growth, were related to contaminant levels in the sediment and to food quantity in water and sediment.

Only the response of A. aquaticus in the bioassay was correlated with sediment contamination. Food availability in overlying water was much more important for C. riparius and E. virgo, thereby masking potential sediment contaminant effects. We conclude that growth of A. aquaticus was depressed by sediment contamination, whereas growth of E. virgo and C. riparius was stimulated by seston food quantity. We discuss that the trophic state of the ecosystem largely affects the ecological risks of contaminated sediments.     

Distribution of mercury in adult penaeid shrimps from Altata-Ensenada del Pabellón lagoon (SE Gulf of California)

The Altata-Ensenada del Pabellón lagoon system is located in the central part of Sinaloa state, NW Mexico. The major sources of pollution are represented by the waste effluents from the intensive agriculture and the urban sewage from the cities of Culiacán (population of 750 000) and Navolato (population of 50 000). In this lagoon system diverse penaeid shrimps occur; the crystal shrimp Farfantepenaeus brevirostris, the brown shrimp F. californiensis, the blue shrimp Litopenaeus stylirostris, the white shrimp L. vannamei and the Pacific seabob Xiphopenaeus kroyeri. With the purpose of knowing distribution and relative concentrations of Hg in the main tissues of penaeid shrimps, levels of Hg in five species from Altata-Enesenada del Pabellón lagoon on the SE Gulf of California were determined. Analysis were carried out by reducing mercury compounds after acid digestion reduction with SnCl₂ and detection by cold vapour atomic absorption. In general, hepatopancreas was the tissue where Hg was mostly accumulated, followed by muscle and exoskeleton. The sequence of Hg concentrations in the five species studied here for every tissue was: hepatopancreas L. vannamei > F. californiensis > L. stylirostris > F. brevirostris > X. kroyeri; muscle L. stylirostris > F. brevirostris > L. vannamei > F. CALIFORNIENSIS=X. kroyeri and exoskeleton F. brevirostris > F. californiensis > L. vannamei > L. stylirostris > X. kroyeri.     

Effect of some heavy metals and soil humic substances on the phytochelatin production in wild plants from silver mine areas of Guanajuato, Mexico

Phytochelatins (PCs) were determined in the wild plants, focusing on their relationship with the levels of heavy metals and humic substances (HS) in soil. Ricinus communis and Tithonia diversifolia were collected from several sites in Guanajuato city (Mexico), which had long been the silver and gold mining center. The analysis of PCs in root extracts was carried out by liquid chromatography (derivatization with monobromobimane). Total Ag, Cd, Cu and Pb in plant roots and in soil samples, as well as soil HS were determined. The association of metals with HS in soils was evaluated by size exclusion chromatography (SEC) with UV and ICP-MS detection. The results obtained revealed the induction of PCs in R. communis but not in T. diversifolia. The levels of Cd and Pb in plant roots presented strong positive correlation with PC-2 (r = 0.9395, p = 0.005; r = 0.9573, p = 0.003, respectively), indicating that these two metals promote PCs induction in R. communis. On the other hand, the inverse correlation was found between soil HS and metal levels in roots of R. communis (Cu > Pb > Cd > Ag), in agreement with the decreasing affinity of these metals to HS. Importantly, the inverse correlation between soil HS and plant PC-2 was observed (r = −0.7825, p = 0.066). These results suggest that metals strongly bound to HS could be less bioavailable to plants, which in turn would limit their role in the induction of PCs. Indeed, the SEC elution profiles showed Pb but not Cd association with HS and the correlation between metal in soil and PC-2 in plant was statistically significant only for Cd (r = 0.7857, p = 0.064). Based on these results it is proposed that the role of heavy metals in PCs induction would depend on their uptake by R. communis, which apparently is controlled by the association of metals with soil HS. This work provides further evidence on the role of environmental conditions in the accumulation of heavy metals and phytochelatin production in plants.     

Biotransformation and antioxidant response in Ceratophyllum demersum experimentally exposed to 1,2- and 1,4-dichlorobenzene

We report the effects of 1,2- and 1,4-dichlorobenzene (1,2-DCB and 1,4-DCB) on the aquatic macrophyte Ceratophyllum demersum. We evaluated the response of the antioxidant system through the assay of glutathione reductase (GR), guaiacol peroxidase (POD) and glutathione peroxidase (GPx). Additionally, the effect of DCBs on the detoxication system by measuring the activity of glutathione-S-transferase (GST) was evaluated.

C. demersum showed elevated GST activities when exposed to 10 and 20 mg l⁻¹ 1,2-DCB, and at 10 mg l⁻¹ for 1,4-DCB. These results show that glutathione conjugation take place at relatively high concentrations of both isomers. Significantly increased activities of POD were also detected in C. demersum exposed to concentrations above 5 mg l⁻¹ of the corresponding isomer.

The GR activity was enhanced in plants exposed to 1,2-DCB (5 mg l⁻¹) and 1,4-DCB (10 mg l⁻¹). GPx was also significantly increased in exposures to the corresponding isomer, each at a concentration of 10 mg l⁻¹. However, plants exposed to low doses of 1,4-DCB (1 mg l⁻¹) showed significantly decreased activities of both enzymes GR and GPx.

Consequently, it is clear that the exposure of the aquatic macrophyte C. demersum to DCBs is able to cause an activation of the antioxidant system, showing an isomer specific pattern, which suggests that the defence system of this plant is playing an important role in scavenging ROS, helping to protect the organism against adverse oxidative effects generated by the prooxidant action of the tested xenobiotics. Furthermore, increased GST activities give indirect evidence on the conjugation of either DCBs or the corresponding metabolites during phase II of detoxication, which supports the elimination process of toxic metabolites from cells of C. demersum.     

A microcosm approach to assessing the effects of earthworm inoculation and oat cover cropping on CO2 fluxes and biological properties in an amended semiarid soil

We designed a microcosm experiment to assess the influence of inoculation with Eisenia foetida earthworms and the establishment of an Avena sativa cover crop on biological (enzyme activities and labile carbon fractions) soil quality indicators in a soil treated with a composted organic residue, and to determine the contribution of these treatments to carbon dioxide emissions from the soil to the atmosphere of the microcosm. The microcosms were incubated for 53 days under 28 °C/18 °C day/night temperatures. The addition of earthworms and the planting of A. sativa increased dehydrogenase activity of compost amended soil by about 44% after 23 days of incubation. The metabolic potential, calculated as the ratio dehydrogenase activity/water soluble C, was higher in the compost amended soil planted with A. sativa. The highest total amount of CO₂–C evolved occurred in the soil treated with composted residue and earthworms (about 40% of the total amount of CO₂ evolved came from earthworm activity). The planting of A. sativa increased the decomposition rate constant of organic matter in the amended soil but decreased the potentially mineralizable C pool. In conclusion, the establishment of an A. sativa cover crop and the addition of E. foetida to a degraded agricultural soil treated with composted residue were effective treatments for improving the biological and biochemical quality and the metabolic potential of the soil.     

Phytoremediation of radiostrontium ((90)Sr) and radiocesium ((137)Cs) using giant milky weed (Calotropis gigantea R.Br.) plants

Potential of plants to remove radionuclides/toxic elements from soils and solutions can be successfully applied for removal of important radionuclides such as strontium-90 (⁹⁰Sr) and cesium-137 (¹³⁷Cs). When uptake of ¹³⁷Cs and ⁹⁰Sr by Calotropis gigantea plants incubated in distilled water spiked with the radionuclides either alone or in combination was studied, it was found to have a high efficiency for the removal of ⁹⁰Sr, with 90% being removed from solutions (5 × 10³ kBq l⁻¹) within 24 h of incubation. However, in case of ¹³⁷Cs, about 44% could be removed from solutions (5 × 10³ kBq l⁻¹) at the end of 168 h of incubation. Accumulation of ⁹⁰Sr and ¹³⁷Cs was higher in roots compared to shoots. The plants could remediate both ⁹⁰Sr and ¹³⁷Cs when they were added together to the solution. When two months old plants were incubated in low level nuclear waste, 99% of activity disappeared at the end of 15 days. The present study suggests that C. gigantea could be used as a potential candidate plant for phytoremediation of ⁹⁰Sr and ¹³⁷Cs.     

The copper tolerance strategies and the role of antioxidative enzymes in three plant species grown on copper mine

This study was undertaken to identify the strategies and the status of antioxidant enzyme activities involved in three plant species tolerance against Cu-toxicity in copper mine. The following methods were used for evaluations in three wild type species; Datura stramonium, Malva sylvestris and Chenopodium ambrosioides. The level of chlorophyll and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) by spectrometry, malondialdehyde (MDA) and dityrosine by HPLC and the levels of Cu in tissues and soils by atomic absorption spectrometry (AAS).

Analysis showed that total and available copper were at toxic levels for plants growing on contaminated soil (zone 1). However, there were not any visual and conspicuous symptoms of Cu toxicity in plant species. Among three species, excess copper was transferred only into the D. stramonium and C. ambrosioides tissues. The C. ambrosioides accumulated Cu in roots and then in leaves, in which the leaves chloroplasts stored Cu around two times of vacuoles. In D. stramonium most of Cu was accumulated in leaves in which the storage rate in vacuoles and chloroplasts were 42% and 8%, respectively. In zone 1, the chlorophyll levels increased significantly in leaves of C. ambrosioides with respect to the same plant growing on uncontaminated soil (zone 2). There was insignificant decrease in chlorophyll content of D. stramonium leaves, collected from zone 1 with respect to zone 2. The D. stramonium and C. ambrosioides in zone 1, both revealed significant increase in their tissues antioxidant enzyme activities in comparison with the same samples of zone 2. There was significant elevation in oxidative damage biomarkers; MDA and dityrosine, when the aerial parts of D. stramonium in zone 1 were compared with the same parts of zone 2.

We concluded that there were different tolerance strategies in studied plant species that protected them against copper toxicity. In M. sylvestris, exclusion of Cu from the roots or its stabilization in the soil restricted Cu toxicity effects. On the other hand D. stramonium and C. ambrosioides, elevated their antioxidative enzyme activities in response to cu-toxicity. In addition, the species D. stramonium accumulated excess of Cu in leaves vacuoles.     

Determination of dithiocarbamate fungicide propineb and its main metabolite propylenethiourea in airborne samples

A simple, rapid and sensitive GC–MS method for the determination of dithiocarbamate fungicide propineb [polymeric zinc propylenebis (dithiocarbamate)] and an improved HPLC procedure for the simultaneous determination of its main metabolite, propylenethiourea, and ethylenethiourea, the main metabolite of all ethylenedithiocarbamates, in airborne samples are described. The method for the analysis of propineb involves the evolution of carbon disulfide (CS₂), under acidic conditions in the presence of stannous chloride, extraction of the generated CS₂ into a layer of isooctane which is then analyzed for CS₂ content by GC–MS in SIM mode. Under the optimum conditions, the retention time of CS₂ was 1.89 min and the total time of chromatographic analysis was 5 min. Recoveries from spiking glass microfibre filters (GF/A) and silica gel filters were 86 ± 7 (n = 9) and 89 ± 4 (n = 9), respectively. The limit of detection is 0.7 ng per filter, which is equivalent to about 0.8–1.0 ng m⁻³ in air. In parallel, an HPLC method with ultraviolet detection is presented for the simultaneous analysis of the metabolites. Separation of the two metabolites was attained in less than 5 min. Recoveries from spiking GF/A and silica gel filters for ethylenethiourea were 100 ± 1 (n = 3) and 98 ± 2 (n = 3), respectively, while for propylenethiourea were 102 ± 1 (n = 3) and 98 ± 1 (n = 3), respectively. The detection limits are about 36–43 and 40–49 ng m⁻³ in air for ethylenethiourea and propylenethiourea, respectively. All the analytes spiked in the filters are proven to be stable for more than one month, at −4 °C.     

Multi-generation studies with Chironomus riparius--effects of low tributyltin concentrations on life history parameters and genetic diversity

While toxicological data are available for numerous chemicals from standard tests, little is known on effects of pollutants over several generations or regarding chronic effects of chemicals on genetic diversity. Within the experiments, effects of the model pollutant tributyltin (TBT) were investigated over eleven generations at a sublethal TBT concentration of 4.46 μg as Sn kg⁻¹ sediment dw on life-cycle parameters and genetic variability of Chironomus riparius. Moreover, the adaptation potential towards TBT was determined. This experimental design enables the identification of TBT effects on life-cycle parameters and the determination of a potential extinction risk caused by chronic exposure. Furthermore, effects on the genetic structure can be determined, which are not predictable based solely on knowledge of the toxic mode of action of the chemical.

Genetic variety was determined via microsatellite analysis, measuring individual length differences of highly variable satellite DNA fragments. For the identification of changes in tolerances towards the stressor, acute and chronic toxicity experiments were conducted.

During the multi-generation study, significant effects on development and reproduction were determined. For some generations, the emergence was significantly (p < 0.05) delayed under TBT exposure. Reproduction seems to be a sensitive parameter as well, whereby females laid significantly larger egg masses (p < 0.05) in the latter generations. TBT did not affect the population growth rate nor the genetic variability, while clear deviations from the Hardy–Weinberg equilibrium appeared. The study also provides strong evidence for the acquirement of a higher tolerance towards the stressor in the TBT-exposed group.     

Comparison of trace element concentrations in livers of diseased, emaciated and non-diseased southern sea otters from the California coast

Infectious diseases have been implicated as a cause of high rates of adult mortality in southern sea otters. Exposure to environmental contaminants can compromise the immuno-competence of animals, predisposing them to infectious diseases. In addition to organic pollutants, certain trace elements can modulate the immune system in marine mammals. Nevertheless, reports of occurrence of trace elements, including toxic heavy metals, in sea otters are not available. In this study, concentrations of 20 trace elements (V, Cr, Mn, Co, Cu, Zn, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb, and Bi) were measured in livers of southern sea otters found dead along the central California coast (n = 80) from 1992 to 2002. Hepatic concentrations of trace elements were compared among sea otters that died from infectious diseases (n = 27), those that died from non-infectious causes (n = 26), and otters that died in emaciated condition with no evidence of another cause of death (n = 27). Concentrations of essential elements in sea otters varied within an order of magnitude, whereas concentrations of non-essential elements varied by two to five orders of magnitude. Hepatic concentrations of Cu and Cd were 10- to 100-fold higher in the sea otters in this study than concentrations reported for any other marine mammal species. Concentrations of Mn, Co, Zn, and Cd were elevated in the diseased and emaciated sea otters relative to the non-diseased sea otters. Elevated concentrations of essential elements such as Mn, Zn, and Co in the diseased/emaciated sea otters suggest that induction of synthesis of metallothionein and superoxide dismutase (SOD) enzyme is occurring in these animals, as a means of protecting the cells from oxidative stress-related injuries. Trace element profiles in diseased and emaciated sea otters suggest that oxidative stress mediates the perturbation of essential-element concentrations. Elevated concentrations of toxic metals such as Cd, in addition to several other organic pollutants, may contribute to oxidative stress-meditated effects in sea otters.     

Estrogen equivalent concentration of 13 branched para-nonylphenols in three technical mixtures by isomer-specific determination using their synthetic standards in SIM mode with GC-MS and two new diasteromeric isomers

Thirteen isomers of branched para-nonylphenols (para-NP) in three technical mixtures were isomer-specifically determined using their synthesized standards by SIM of structurally specific ions, m/z 135, 149 or 163 with GC–MS. Of the 13 isomers, four isomers, 4-(2,4-dimethylheptan-4-yl)phenol, 4-(4-methyloctan-4-yl)phenol, 4-(3-ethyl-2-methylhexan-2-yl)phenol (3E22NP) and 4-(2,3-dimethylheptan-2-yl)phenol synthesized for their determinations were first used as standard substances. The 13 isomers in the technical mixtures individually occurred at mass percent portion of more than 2%. The total mass percent portions in the mixtures from Tokyo Chemical Industry (TCI), Aldrich, and Fluka covered with 89 ± 2%, 75 ± 4% and 77 ± 2%, respectively. The abundance of 4-(3,6-dimethylheptan-3-yl)phenol in the three mixtures was the largest with 11.1 ± 2% to 9.9 ± 0.3%, while that of 4-(2-methyloctan-2-yl)phenol was the smallest with 2.9 ± 0.3% to 3.0 ± 0.2%. Additionally, structures of four new isomers of more than 1% portion present in a technical mixture were elucidated as two pairs of diastereomeric isomers: two types of 4-(3,4-dimethylheptan-4-yl)phenol (344NP) and those of 4-(3,4-dimethylheptan-3-yl)phenol (343NP). By estrogenic assay of 13 isomers with yeast estrogen screen system, the activity of 3E22NP was the highest, while that of 4-(3-methyloctan-3-yl)phenol was the least. Their relative activities to that of 3E22NP were individually calculated. Estrogenic equivalent concentrations of the three technical mixtures were predictively evaluated. The ratio of the EEC to the conventional concentration, total mass percent portions of the 13 isomers in technical mixtures were 0.208 for TCI, 0.206 for Aldrich and 0.205 for Fluka. The predicted estrogenic activity of measured concentration of para-NP in technical mixtures was approximately 5-fold greater than the measured estrogen agonist activity.     

Cold season CH4, CO2 and N2O fluxes from freshwater marshes in northeast China

Cold season (winter and thaw) CH₄, CO₂ and N₂O fluxes from freshwater marshes (47°35′N, 133°31′E, Northeast China) were measured, using the static chamber method. The mean CH₄ and CO₂ fluxes from Carex lasiocarpa (Cl) were 0.5 ± 0.19 and 6.23 ± 1.36 mg C m⁻² h⁻¹, respectively, and those from Deyeuxia angustifoli (Da) were 0.18 ± 0.15 and 5.22 ± 2.48 mg C m⁻² h⁻¹, respectively in winter. There was no significant difference between Cl and Da (p > 0.05). The contributions of winter CH₄ fluxes were about 5.5% and 3% in the Cl and Da, respectively. Marshes are an important potential N₂O sink in winter season in northeast China. During thaw, the CH₄ and CO₂ emissions rapidly increased, 4.5–6 times of winter emissions. Wetland became a source of N₂O. Cold season gases flux from northern wetlands play an important role in the seasonal gas exchange.     

Utilization and degradation of imazaquin by a naturally occurring isolate of Arthrobacter crystallopoietes

A species of bacteria that is capable of utilizing imazaquin as the sole carbon source was isolated from soil with repeated imazaquin applications, and was identified as Arthrobacter crystallopoietes (designated as strain “WWX-1”). This isolate degrades imazaquin as high as 200 μg ml⁻¹, and the estimated dissipation half-lives increased from 1.51 d for the treatment at 50 μg ml⁻¹ to 4.75 d for 200 μg ml⁻¹. Optimal growth of WWX-1 in mineral salt medium with 50 μg ml⁻¹ imazaquin was obtained at 35 °C and a pH of 5.0. Growth of WWX-1 was also observed in mineral salt medium with the addition of other imidazolinone herbicides such as imazethapyr and imazapyr, but not with different classes of herbicides such as metsulfuron-methyl. Two imazaquin metabolites were detected, and spectral analysis with HPLC–MS, ¹H NMR, and IR revealed one metabolite with a molecular weight (MW) of 199 as quinoline-2,3-dicarboxylic anhydride. We propose that A. crystallopoietes (WWX-1) could serve as an efficient biodegradation system for remediation of water and soils that are heavily contaminated with imazaquin or other structurally similar chemicals.     

Biodegradation kinetics and toxicity of vegetable oil triacylglycerols under aerobic conditions

The aerobic biodegradation of five triacylglycerols (TAGs), three liquids [triolein (OOO), trilinolein (LLL), and trilinolenin (LnLnLn)] and two solids [tripalmitin (PPP) and tristearin (SSS)] was studied in water. Respirometry tests were designed and conducted to determine the biochemical oxygen demand (BOD) parameters of the compounds. In the case of the solid lipids, the degradation process was limited by their extremely non-polar nature. When added to water, PPP and SSS formed irregular clumps or gumballs, not a fine and uniform suspension required for the lipase activity. After 30 days, appreciable mineralization was not achieved; therefore, first-order biodegradation coefficients could not be determined. The bioavailability of the liquid TAGs was restricted due to the presence of double bonds in the fatty acids (FAs). An autoxidation process occurred in the allylic chains, resulting in the production of hydroperoxides. These compounds polymerized and became non-biodegradable. Nevertheless, the non-oxidized fractions were readily mineralized, and BOD rate constants were estimated by non-linear regression: LLL (k = 0.0061 h⁻¹) and LnLnLn (k = 0.0071 h⁻¹) were degraded more rapidly than OOO (k = 0.0025 h⁻¹). Lipids strongly partitioned to the biomass and, therefore, Microtox^® toxicity was not observed in the water column. However, EC₅₀ values (<15% sample volume) were measured in the solid phase.     

Toxicity of HC Orange No. 1 to Daphnia magna, zebrafish (Brachydanio rerio) embryos, and goldfish (Carassius auratus)

HC Orange No. 1 (HCO1; 2-nitro-4′-hydroxydiphenylamine) (CAS No. 54381-08-7) is used as a color additive in hair dyes and can be released into aquatic environments in wastewater. In this paper, the effects of HCO1 on aquatic organisms were studied using a battery of toxicological tests. These included measuring immobilization of Daphnia magna, inhibition of zebrafish embryo development, and acute lethality in zebrafish and goldfish, which are different species belonging to different trophic levels. HCO1 was toxic to all of the organisms studied. In our experiments, HCO1 remarkably restrained the mobility of D. magna, which may cause subsequent death. The EC₅₀ value for restrained the mobility of D. magna at 48 h was 1.54 mg HCO1 l⁻¹. In addition, HCO1 showed toxicity in zebrafish and goldfish, where LC₅₀values at 96 h were 4.04 and 5.37 mg l⁻¹, respectively. The results also indicated that HCO1 remarkably retarded the development of zebrafish embryos, which may cause embryo abnormality and even lethality. The most sensitive toxicological endpoint in the development of the embryos was failure to hatch, which had an EC₅₀ of 0.19 mg HCO1 l⁻¹. These results indicated that HCO1 is a potential teratogen to zebrafish embryos. In addition, as HCO1 concentrations increased, the outcomes of each of these toxicity tests changed in a concentration-dependent manner. Together, the results revealed that HCO1 appears to be toxic to multiple different species of aquatic organisms. The EC₅₀ (LC₅₀) values contain sufficient discriminatory power for risk assessment of HCO1 in aquatic environments. Based on the present results, more efficient risk assessment procedures for HCO1 will be designed in the future, integrating more flexible testing methods into the testing schemes that employ only the necessary tools for each case.     

Seasonal variations of monoterpene emissions from coniferous trees of different ages in Korea

Seasonal variations of emission rates and compositions from coniferous species were measured under controlled conditions using a vegetation enclosure method. Total emission rates and compositions of monoterpene compounds from young and adult trees in different seasons were compared.

It was found that the total emission rates and the components of monoterpene varied significantly with tree species, age, and season. Total emissions from C. japonica and P. koraiensis were higher for older trees than for younger trees; however, significantly higher emissions were found from younger trees for C. obtusa. Higher monoterpene emission rates from each plant were found in spring and summer compared with autumn and winter emissions.