Determination of Oxidative Metabolism in Collembolan Proisotoma minuta (Tullberg)

An oxidative metabolism of Collembolan Proisotoma minuta was determined with a model compound of aldrin and dieldrin in this paper. The seven-day LD₅₀ values for aldrin, dieldrin, and piperonyl butoxide in salt solution were 0.496, 0.367, and 8.346 mg L^?1, respectively. When P. minuta were exposed to aldrin, dieldrin was the sole metabolite. The conversion of aldrin to dieldrin was known to be catalyzed by P450 monooxygenases system. It has been shown that the synergist piperonyl butoxide inhibited the metabolism of aldrin in P. minuta.     

Use of Co speciation and soil properties to explain variation in Co toxicity to root growth of barley (Hordeum vulgare L.) in different soils

The influence of soil properties on the bioavailability and toxicity of Co to barley (Hordeum vulgare L.) root elongation was investigated. Ten soils varying widely in soil properties were amended with seven doses of CoCl₂. Soil properties greatly influenced the expression of Co toxicity. The effective concentration of added Co causing 50% inhibition (EC₅₀) ranged from 45 to 863 mg kg⁻¹, representing almost 20-fold variation among soils. Furthermore, we investigated Co toxicity in relation to Co concentrations and free Co²⁺ activity in soil solution. The EC₅₀ values showed variation among soils of 17- and 29-fold, based on the Co concentration in soil solution and free Co²⁺ activity, respectively. Single regressions were carried out between Co toxicity threshold values and selected soil properties. Models obtained showed that soil effective cation exchange capacity (eCEC) and exchangeable calcium were the most consistent single predictors of the EC₅₀ values based on soil added Co.     

The effects of copper ions and copper nanomaterials on the output of amino acids from marine microalgae

In this study, the marine microalgae Skeletonema costatum and Nitzschia closterium were exposed to different forms of copper, such as a metal salt (Cu²⁺), a nano-metal (nano-Cu), and nano-metal oxide (nano-CuO). During a 96-h exposure to nanoparticles (NPs) and salt, the cell number, Cu²⁺ concentration in the culture medium, morphology, and intracellular amino acids were measured to assess the toxicity of the copper materials and the toxicity mechanism of the NPs. As results, the toxicity of Cu²⁺, nano-Cu, and nano-CuO to marine phytoplankton decreased in order. The EC₅₀ values of Cu²⁺ and nano-Cu for S. costatum and N. closterium ranged from 0.356 to 0.991 mg/L and 0.663 to 2.455 mg/L, respectively. Nano-Cu inhibits the growth of marine phytoplankton by releasing Cu²⁺; however, nano-CuO is harmful to microalgae because of the effect of NPs. The secretion of extracellular polymeric substances by microalgae could also affect the toxicity of nano-Cu and nano-CuO to microalgae. S. costatum was more sensitive to copper than N. closterium. Cu²⁺, nano-Cu, and nano-CuO all reduced per-cell amino acids and the total output of algae-derived amino acids by affecting the growth of the phytoplankton. This study helps to understand the risk assessment of nano-Cu and nano-CuO to marine microalgae.

     

Acute toxicity assessment of explosive-contaminated soil extracting solution by luminescent bacteria assays

Explosive-contaminated soil is harmful to people’s health and the local ecosystem. The acute toxicity of its extracting solution was tested by bacterial luminescence assay using three kinds of luminescent bacteria to characterize the toxicity of the soil. An orthogonal test L ₁₆ (4⁵) was designed to optimize the soil extracting conditions. The optimum extracting conditions were obtained when the ultrasonic extraction time, ultrasonic extraction temperature, and the extraction repeat times were 6 h, 40 °C, and three, respectively. Fourier transform infrared spectroscopy (FTIR) results showed that the main components of the contaminated soil’s extracting solution were 2,4-dinitrotoluene-3-sulfonate (2,4-DNT-3-SO₃ ⁻); 2,4-dinitrotoluene-5-sulfonate (2,4-DNT-5-SO₃ ⁻); and 2,6-dinitrotoluene (2,6-DNT). Compared with Photobacterium phosphoreum and Vibrio fischeri, Vibrio qinghaiensis sp. Nov. is more suitable for assessing the soil extracting solution’s acute toxicity. Soil washing can remove most of the contaminants toxic to luminescent bacterium Vibrio qinghaiensis sp. Nov., suggesting that it may be a potential effective remediation method for explosive-contaminated soil.

     

Experimental Variability in Characterization of Cyfluthrin Sorption to Soil

To assess the risk of a pesticide to leach to groundwater or to run off to surface water after application, it is necessary to characterize the sorption of the pesticide to soil. For pyrethroids, their hydrophobicity, strong sorption to various materials, and low solubility make it difficult to accurately characterize sorption processes. The objective of this research was to evaluate the variability in cyfluthrin ((RS)-α -cyano-4-fluoro-3-phenoxybenzyl (1RS,3RS;1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate) sorption to soil as affected by experiment conditions. To minimize cyfluthrin sorption on the walls of glass, silanized-glass, stainless steel, and PTFE centrifuge tubes, cyfluthrin solution was added to aqueous soil slurries or directly to soil, after which it was equilibrated with aqueous solution. Depending on the soil, variation in sorption coefficients, K _oc, obtained using different experimental methodologies with one soil can be comparable to the variation in K _oc values obtained for soils with different physical and chemical properties using one method. K _oc values for cyfluthrin ranged from 56,000 to 300,000 L kg^?1. Sorption methodology needs to be evaluated before sorption coefficients are used in predictive transport models.     

Application of an artificial sea salt solution to determine acute toxicity of herbicides to Proisotoma minuta (Collembola)

The acute toxicity test is described in this experiment where the Collembola species Proisotoma minuta was exposed to herbicides in an artificial sea salt solution for seven days. The salt solution did not prohibit the insects' reproduction system. The seven day LD50 values for trifluralin, pendimethalin, metolachlor, prometryn, paraquat, atrazine, fluometuron, and diuron were 3.48, 10.4, 12.4, 13.0, 23.1, 33.4, 250, and 711 mg L(-1), respectively. A good correlation between toxicity of the compounds and their lipophilicity and vapor pressure was recorded in this study.     

Distribution Equilibrium of Mercury (II) Chloride between Water and Air Applied to Flue Gas Scrubbing

ABSTRACT

In the literature, different values of the distribution coefficient K_H for HgCl₂ between water and air are present in a range that spans more than 3 orders of magnitude. In order to determine if a waste incineration scrubber solution could become saturated with regard to HgCl₂, an accurate experimental determination of the distribution constant of HgCl₂ at elevated temperatures is needed. In this work, the coefficient has been determined at four different temperatures between 10 and 50 °C. The Arrhenius expression obtained is 5.5 x 10⁵ x exp[-(8060 ± 2200)/7] with a corresponding enthalpy for the process HgCl₂(aq)<» HgCl₂(g) of 67 ± 20 kJ/mole. K_H at 293 K was found to be ~5 x 10^-7 atm M^-1, which is in almost perfect agreement with an earlier study. Applying the obtained K_H values to waste incineration scrubber conditions shows that no major saturation effect will occur.     

Evaluation of the capacity of the cyanobacterium Microcystis novacekii to remove atrazine from a culture medium

The bioaccumulation of atrazine and its toxicity were evaluated for the cyanobacterium Microcystis novacekii. Cyanobacterial cultures were grown in WC culture medium with atrazine at 50, 250 and 500 μg L^?1. After 96 hours of exposure, 27.2% of the atrazine had been removed from the culture supernatant. Spontaneous degradation was found to be insignificant (< 9% at 500 μg L^?1), indicating a high efficiency for the bioaccumulation of atrazine by M. novacekii. There were no atrazine metabolites detected in the culture medium at any of the doses studied. The acute toxicity (EC₅₀) of atrazine to the cyanobacterium was 4.2 mg L^?1 at 96 hours demonstrating the potential for M. novacekii to tolerate high concentrations of this herbicide in fresh water environments. The ability of M. novacekii to remove atrazine combined with its tolerance of the pesticide toxicity showed in this study makes it a potential biological resource for the restoration of contaminated surface waters. These findings support continued studies of the role of M. novacekii in the bioremediation of fresh water environments polluted by atrazine.     

Toxicity of new pyrethroid in pest insects Asciamonuste and Diaphania hyalinata,predator Solenopsis saevissima and stingless bee Tetragonisca angustula

There is increasing demand for new products for vegetable pest management. Thus, the aim of this study was to assess the toxicity of pyrethroids with acid moiety modifications to measure the insecticidal activity of these compounds on the lepidopteran vegetable pests Diaphania hyalinata (L.) (Lepidoptera: Pyralidae) and Asciamonuste (Latreille) (Lepidoptera: Pieridae) and evaluate their selectivity for the predatory ant Solenopsis saevissima (F. Smith) (Hymenoptera: Formicidae) and pollinator Tetragonisca angustula (Latreille) (Hymenoptera: Apidae: Meliponinae). Racemic mixtures of five new pyrethroids (30 µg molecule mg^?1 insect body weight) resulted in high (100%) and rapid (stable LD₅₀ after 12 h) mortality in D. hyalinata and A. monuste. In A. monuste, the trans-pyrethroid [12] isomer showed similar toxicity to permethrin. For D. hyalinata, the trans-pyrethroid [9] isomer and cis-pyrethroid [10] isomer were as toxic as permethrin. Due to their low selectivity, these new pyrethroids should be applied on the basis of ecological selectivity principles to minimize impacts on nontarget organisms S. saevissima and T. angustula.     

Mixture Toxicity of the Antifouling Compound Irgarol to the Marine Phytoplankton Species Dunaliella tertiolecta

This study examined the toxicity of irgarol, individually and in binary mixtures with three other pesticides (the fungicide chlorothalonil, and the herbicides atrazine and 2,4-D), to the marine phytoplankton species Dunaliella tertiolecta. Standard 96-h static algal bioassays were used to determine pesticide effects on population growth rate. Irgarol significantly inhibited D. tertiolecta growth rate at concentrations ≥ 0.27 μ g/L. Irgarol was significantly more toxic to D. tertiolecta than the other pesticides tested (irgarol 96 h EC₅₀ = 0.7 μ g/L; chlorothalonil 96 h EC₅₀ = 64 μ g/L; atrazine 96 h EC₅₀ = 69 μ g/L; 2,4-D 96 h EC₅₀ = 45,000 μ g/L). Irgarol in mixture with chlorothalonil exhibited synergistic toxicity to D. tertiolecta, with the mixture being approximately 1.5 times more toxic than the individual compounds. Irgarol and atrazine, both triazine herbicides, were additive in mixture. The toxicity threshold of 2,4-D was much greater than typical environmental levels and would not be expected to influence irgarol toxicity. Based on these interactions, overlap of certain pesticide applications in the coastal zone may increase the toxicological risk to resident phytoplankton populations.     

Toxicity identification evaluation of anaerobically treated swine slurry: A comparison between Daphnia magna and Raphanus sativus

Anaerobic digestion does not efficiently reduce ionic compounds present in swine slurry, which could present a potential risk to aquatic ecosystems (surface runoff) and terrestrial ambient (irrigation). The objective of this study was to evaluate the ecotoxicological characteristics of anaerobically treated swine slurry using acute and chronic (epicotyl elongation) toxicity tests with Daphnia magna and Raphanus sativus and identification of suspected toxic compounds using the Toxicity Identification Evaluation (TIE) method. The evaluation was performed in three phases: physicochemical characterization of the slurry; acute/chronic toxicity testing with Daphnia magna and Raphanus sativus for each fraction of the TIE (cation and anion exchange columns, activated carbon, pH modification/aeration and EDTA) and identification of suspected toxic compounds. The anaerobically treated slurry contained concentrations of ammonium of 1,072 mg L^?1, chloride of 815 mg L^?1 and metals below 1 mg L^?1 with a D. magna acute toxicity (48h-LC₅₀) of 5.3% and R. sativus acute toxicity (144h-LC₅₀) of 48.1%. Epicotyl elongation of R. sativus was inhibited at concentrations above 25% (NOEC). The cation exchange reduced the toxicity and free ammonia by more than 90% for both bio-indicators. Moreover, this condition stimulated the epicotyl growth of R. sativus between 10% and 37%. In conclusion, the main compound suspected of causing acute toxicity in D. magna and acute/chronic toxicity in R. sativus is the ammonium. The findings suggest the need the ammonium treatment prior to the agricultural reuse of swine slurry given the high risk to contaminate the aquatic environment by runoff and toxicity of sensitive plants.     

Formaldehyde Concentrations Inside Private Residences: A Mail-Out Approach to Indoor Air Monitoring

Abstract

The main objective of this study was to monitor the volatile organic compounds (VOCs) in the stack gas released from organic chemical industrial plants to determine emission factors. Samples from 52 stacks, with or without air pollution control devices (APCDs), from seven industrial processes were taken and VOCs measured using U.S. Environmental Protection Agency (EPA) Method 18. These 7 processes, including 26 plants, were the manufacturers of acrylonitrile–butadiene–styrene (ABS), polyvinyl chloride (PVC), polystyrene (PS), acrylic resin (ACR), vinyl chloride (VC), para–terephthalic acid (PTA), and synthetic fiber (SYF). The results clearly indicate significant variations of emission factors among the various industrial processes, particularly emission factors for those without APCDs. As expected, those with APCDs yield much less emission factors. Regardless of those with or without APCDs, the order of manufacturing processes with regard to VOC emission factors is SYF > ABS > PS > ACR > PTA > PVC > VC. The emission factors for some processes also differ from those in EPA–42 data file. The VOC profiles further indicate that some VOCs are not listed in the U.S. VOC/Particulate Matter Speciation Data System (SPECIATE). The potential O₃ formation is determined from the total amount of VOC emitted for each of seven processes. The resultant O₃ yield varied from 0.22 (ACR) to 2.33 g O₃ g^–1 VOC (PTA). The significance of this O₃ yield is discussed.     

Fungicide sensitivity of Trichoderma spp. from Agaricus bisporus farms in Serbia

Trichoderma species, the causal agents of green mould disease, induce great losses in Agaricus bisporus farms. Fungicides are widely used to control mushroom diseases although green mould control is encumbered with difficulties. The aims of this study were, therefore, to research in vitro toxicity of several commercial fungicides to Trichoderma isolates originating from Serbian and Bosnia-Herzegovina farms, and to evaluate the effects of pH and light on their growth. The majority of isolates demonstrated optimal growth at pH 5.0, and the rest at pH 6.0. A few isolates also grew well at pH 7. The weakest mycelial growth was noted at pH 8.0–9.0. Generally, light had an inhibitory effect on the growth of tested isolates. The isolates showed the highest susceptibility to chlorothalonil and carbendazim (ED₅₀ less than 1 mg L^?1), and were less sensitive to iprodione (ED₅₀ ranged 0.84–6.72 mg L^?1), weakly resistant to thiophanate-methyl (ED₅₀ = 3.75–24.13 mg L^?1), and resistant to trifloxystrobin (ED₅₀ = 10.25–178.23 mg L^?1). Considering the toxicity of fungicides to A. bisporus, carbendazim showed the best selective toxicity (0.02), iprodione and chlorothalonil moderate (0.16), and thiophanate-methyl the lowest (1.24), while trifloxystrobin toxicity to A. bisporus was not tested because of its inefficiency against Trichoderma isolates.     

In vitro toxicity of fungicides with different modes of action to alfalfa anthracnose fungus,Colletotrichum destructivum

Abstract

Sensitivity of 24 isolates of Colletotrichum destructivum O’Gara, collected from alfalfa plants in Serbia, to eight selected fungicides, was investigated in this study. Molecular identification and pathogenicity test of isolates tested were also performed. Fungicide sensitivity was evaluated in vitro, using mycelial growth assay method. All isolates exhibited significant pathogenicity, causing necrosis at the alfalfa seedling root tips two days after inoculation. Using the primer pair GSF1-SR1 and by comparing the amplified fragments of the tested isolates with the marker (M), the presence of the amplicon of the expected size of about 900?bp was determined for all isolates. The isolates tested in this study showed different sensitivity towards fungicides in vitro. Mycelial growth was highly inhibited by QoI (quinone outside inhibitors) fungicide pyraclostrobin (mean EC₅₀=0.39?µg mL^?1) and by DMI (demethylation-inhibiting) fungicide tebuconazole (mean EC₅₀=0.61?µg mL^?1), followed by azoxystrobin (mean EC₅₀=2.83?µg mL^?1) and flutriafol (mean EC₅₀=2.11?µg mL^?1). Multi-site fungicide chlorothalonil and MBC (methyl benzimidazole carbamate) fungicide thiophanate-methyl evinced moderate inhibition with mean EC₅₀=35.31 and 62.83?µg mL^?1, respectively. Thirteen isolates were sensitive to SDHI (succinate dehydrogenase inhibitors) fungicide boscalid and fluxapyroxad, (mean EC₅₀=0.49 and 0.19?µg mL^?1, respectively), while the rest of isolates were highly resistant.     

Assessing the toxicity of sodium chloride to the glochidia of freshwater mussels: implications for salinization of surface waters

Chloride concentrations in surface waters have increased significantly, a rise attributed to road salt use. In Canada, this may be a concern for endangered freshwater mussels, many with ranges limited to southern Ontario, Canada’s most road-dense region. The acute toxicity of NaCl was determined for glochidia, the mussel’s larval stage. The 24 h EC50s of four (including two Canadian endangered) species ranged from 113-1430 mg Cl L⁻¹ (reconstituted water, 100 mg CaCO₃ L⁻¹). To determine how mussels would respond to a chloride pulse, natural river water (hardness 278-322 mg CaCO₃ L⁻¹) was augmented with salt. Lampsilis fasciola glochidia were significantly less sensitive to salt in natural water (EC50s 1265-1559 mg Cl L⁻¹) than in reconstituted water (EC50 285 mg L⁻¹). Chloride data from mussel habitats revealed chloride reaches levels acutely toxic to glochidia (1300 mg L⁻¹). The increased salinization of freshwater could negatively impact freshwater mussels, including numerous species at risk.     

Sorption of chlorpyrifos and fonofos on four soils and turfgrass thatch using membrane filters

Abstract

Chemical transport in soil is a major factor influencing soil and water contamination. Four soils and turfgrass thatch, representing a wide range of organic carbon OC content were studied to determine sorption K_d and K_f parameters for the insecticides chlorpyrifos and fonofos. The batch equilibrium method was used. The concentration of insecticide was measured in the solution as well as in the solid phase to determine the most accurate sorption data. Four soils and thatch were equilibrated for 24 h at 22 ± 1^OC with aqueous insecticide solutions. Four concentrations of the insecticides, each <50% of their respective water solubilities, were selected for the experiments. After extraction with an organic solvent, the concentration of insecticides in the aqueous solution was determined by gas liquid chromatography using electron capture detection for chlorpyrifos, and nitrogen/phosphorus detection for fonofos. Data obtained were fitted to the log and simple linear form of the Freundlich equation. Mass balance Freundlich isotherm exponents n ranged between 0.82 and 0.93 for chlorpyrifos. 0.82 and 1.21 for fonofos, with r² ≥ 0.97. K_oc (percent of organic carbon %OC normalized Sorption coefficient) values were calculated by using experimentally developed K_d and K_f coefficients in relation to OC levels from 0.29 to 34.85%. K_d and K_f coefficients of both insecticides were positively correlated with OC (r² ≥ 0.96). organic matter OM (r² ≥ 0.96), and cation exchange capacity CEC (r² ≥ 0.90).     

Microwave synthesis and antifungal evaluations of some chalcones and their derived diaryl-cyclohexenones

Microwave irradiation (MWI) of acetophenones and substituted benzaldehydes in water resulted in a “green-chemistry” procedure for the preparation of chalcones (1-14), through base catalyzed Claisen-Schmidt condensation reaction, in good yields. Further 3,5-diaryl-6-carbethoxy-2-cyclohexen-1-ones (1a-14a) were prepared through base catalyzed cyclocondensation of above chalcones with ethylacetoacetate using MWI as the energy source and silica as support. Out of fourteen cyclohexenones, ten (1a, 4a, 5a, 6a, 7a, 9a, 10a, 11a, 12a and 13a) are reported for the first time in literature. The synthesized compounds were characterized using various spectroscopic techniques, viz. (¹H NMR and IR) and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be active against R. solani whereas against S. rolfsii, moderate activity was observed, as evident from LC₅₀ values. The most potent compounds against R. solani were 1-(4-Fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-Diphenyl-propenone (14) having LC₅₀ values of 2.36 and 2.49 mgL^{? 1} respectively (LC₅₀ of Hexaconazole = 1.12 mgL^{? 1}) and against S. rolfsii 3-(4-Fluoro-phenyl)-5-(3-nitro-phenyl)-6-carbethoxy-2-cyclohexen-1-one (12a) was most active having LC₅₀ value of 285 mgL^{? 1}compared to Hexaconazole (LC₅₀ = 1.27 mgL^{? 1}).     

Evaluation of the mobility of c14‐labelled pesticides in soils by thin layer chromatography using a linear analyser

Abstract

The mobility of seven pesticides in a chromic cambisol soil was studied by soil thin layer chromatography. Pesticide mobilities were determined by means of conventional autoradiographs of the chromatograms, as well as from sequential series of curves and images of the pesticide spots provided by a linear analyser. The R _f values obtained from the autoradiographs and those provided by the linear analyser were quite consistent. Based on such values, pesticide mobility decreased in the following order: acephate > fluometuron > atrazine > ethofumesate > metolachlor > diazinon > glyphosate. According to the mobility scale proposed by Helling and Turner (1968), acephate is highly mobile; atrazine, fluometuron, ethofumesate and metolachlor are moderately mobile; diazinon is slightly mobile; and glyphosate is immobile. The images provided by the linear analyser allow to determine the R _f values for the zones of maximum activity in the pesticide spots (R _f ^max), as well as the activities of different spot zones and those corresponding to R _f and R _f ^max. The results obtained show the image analyser to provide more expeditious R _f measurements from the chromatograms and open up new prospects for using soil TLC to investigate pesticide mobility.     

Combined effect of polystyrene plastics and triphenyltin chloride on the green algae Chlorella pyrenoidosa

The combined effect of polystyrene (PS) particles and triphenyltin chloride (TPTCl) to the green algae Chlorella pyrenoidosa was studied. The 96 h IC₅₀ of TPTCl to the green algae C. pyrenoidosa was 30.64 μg/L. The toxicity of PS particles to C. pyrenoidosa was size-dependent, with the 96 h IC₅₀ at 9.10 mg/L for 0.55 μm PS but no toxicity observed for 5.0 μm PS. The exposure to 0.55 μm PS led to damage on structure of algal cells, which could in turn cause inhibition on photosynthesis and population growth of the green algae. TPTCl concentrations in test medium were lowered by 15–19% at presence of 0.55 μm PS particles, indicating a reduced bioavailability of TPTCl. In spite of this reduced bioavailability, the presence of PS increased the toxicity of TPTCl, which might be attributed to facilitated uptake of TPTCl by the green algae after the damage of cell structure. The overall results of the present study provided important information on the effect of PS on the bioavailability and toxicity of TPTCl to phytoplankton species.