Optimization of culturing conditions for isolated Arthrobacter sp. ZXY-2, an effective atrazine-degrading and salt-adaptive bacterium

NARCIS (Netherlands)

Zhao, X.; Wang, Li; Du, Linna; Yang, Jixian; Dong, Jing; Ma, Fang

2017-01-01

The increasing salinity in aquatic environments has had a negative impact on the biodegradation of atrazine, an extensively used herbicide which has been proven to pollute soil and water ecosystems. In the present study, a novel atrazine-degrading strain (ZXY-2) was isolated from industrial

Monod kinetics rather than a first-order degradation model explains atrazine fate in soil mini-columns: Implications for pesticide fate modelling

International Nuclear Information System (INIS)

Cheyns, K.; Mertens, J.; Diels, J.; Smolders, E.; Springael, D.

2010-01-01

Pesticide transport models commonly assume first-order pesticide degradation kinetics for describing reactive transport in soil. This assumption was assessed in mini-column studies with associated batch degradation tests. Soil mini-columns were irrigated with atrazine in two intermittent steps of about 30 days separated by 161 days application of artificial rain water. Atrazine concentration in the effluent peaked to that of the influent concentration after initial break-through but sharply decreased while influx was sustained, suggesting a degradation lag phase. The same pattern was displayed in the second step but peak height and percentage of atrazine recovered in the effluent were lower. A Monod model with biomass decay was successfully calibrated to this data. The model was successfully evaluated against batch degradation data and mini-column experiments at lower flow rate. The study suggested that first-order degradation models may underestimate risk of pesticide leaching if the pesticide degradation potential needs amplification during degradation. - Population dynamics of pesticide degrading population should be taken into account when predictions of pesticide fate are made to avoid underestimation of pesticide break-through towards groundwater.

Laboratory degradation studies of 14C-atrazine and -isoproturon in soil from sugarcane cultivated fields under Kenyan tropical conditions.

Science.gov (United States)

Getenga, Z M; Dörfler, U; Schroll, R

2009-06-01

A study to compare the degradation rates of atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diammine) and isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] in soils from sugarcane fields with different practices of herbicides application was carried out. (14)C-atrazine was poorly mineralized to (14)CO(2) (1.10% +/- 0.22%) after 139 days of incubation in soil without previous exposure to atrazine. In the same soil also with no previous isoproturon exposure isoproturon was mineralized to (14)CO(2) by 7.70% +/- 0.94%. Atrazine mineralization after 98 days was 13.4% +/- 0.30% in soil which discontinued the use of atrazine in 1997 while it was 89.9% +/- 1.23% in soil in which atrazine is currently being used. The isoproturon mineralization values were 7.24% +/- 0.85% and 22.97% +/- 0.96% in soil which discontinued atrazine and soil currently using atrazine, respectively.

The ability of indigenous micro-organisms to degrade isoproturon, atrazine and mecoprop within aerobic UK aquifer systems.

Science.gov (United States)

Johnson, Andrew C; White, Craig; Bhardwaj, C Lal; Dixon, Andy

2003-12-01

The potential for the herbicides isoproturon, atrazine and mecoprop to degrade in the major UK aquifers of chalk, sandstone and limestone was studied using laboratory microcosms spiked at 100 microg litre(-1). Significant mecoprop degradation was only observed in sandstone groundwater samples. Atrazine transformation, based on the formation of metabolites, did occur in most groundwater samples, but only at a rate of 1-3% per year. A potential to degrade isoproturon was observed in groundwater samples from each of the aquifer types, with the most rapid and consistent degradation occurring at the sandstone field site. Biodegradation was confirmed by the formation of monodesmethyl- and didesmethyl-isoproturon. Isoproturon degradation potential rates obtained from the groundwater microcosms could not be correlated with either dissolved organic carbon or numbers of bacteria in the groundwater. It was noted that the ability of the groundwater at a field site to degrade a pesticide was not related to performance of the soil above.

Atrazine degradation and enzyme activities in an agricultural soil under two tillage systems.

Science.gov (United States)

Mahía, Jorge; Martín, Angela; Carballas, Tarsy; Díaz-Raviña, Montserrat

2007-05-25

The content of atrazine and its metabolites (hydroxyatrazine, deethylatrazine and deisopropylatrazine) as well as the activities of two soil enzymes (urease and beta-glucosidase) were evaluated in an acid agricultural soil, located in a temperate humid zone (Galicia, NW Spain), with an annual ryegrass-maize rotation under conventional tillage (CT) and no tillage (NT). Samples were collected during two consecutive years from the arable layer at two depths (0-5 cm and 5-20 cm) and different times after atrazine application. Hydroxyatrazine and deisopropylatrazine were the main metabolites resulting from atrazine degradation in the acid soil studied, the highest levels being detected in the surface layer of the NT treatment. A residual effect of atrazine was observed since hydroxyatrazine was detected in the arable layer (0-5 cm, 5-20 cm) even one year after the herbicide application. Soil enzyme activities in the upper 5 cm layer under NT were consistently higher than those in the same layer under CT. Urease and beta-glucosidase activities decreased with depth in the profile under NT but they did not show any differences between the two depths for the plots under CT. For both tillage systems enzyme activities also reflected temporal changes during the maize cultivation; however, no consistent effect of the herbicide application was observed.

Atrazine degradation using chemical-free process of USUV: Analysis of the micro-heterogeneous environments and the degradation mechanisms

International Nuclear Information System (INIS)

Xu, L.J.; Chu, W.; Graham, Nigel

2014-01-01

Graphical abstract: - Highlights: • Two chemical-free AOP processes are combined to enhance atrazine degradation. • ATZ degradation in sonophotolytic process was analyzed using a previous proposed model. • The micro-bubble/liquid heterogeneous environments in sonolytic processes were investigated. • The salt effects on different sonolytic processes were examined. • ATZ degradation mechanisms were investigated and pathways were proposed. - Abstract: The effectiveness of sonolysis (US), photolysis (UV), and sonophotolysis (USUV) for the degradation of atrazine (ATZ) was investigated. An untypical kinetics analysis was found useful to describe the combined process, which is compatible to pseudo first-order kinetics. The heterogeneous environments of two different ultrasounds (20 and 400 kHz) were evaluated. The heterogeneous distribution of ATZ in the ultrasonic solution was found critical in determining the reaction rates at different frequencies. The presence of NaCl would promote/inhibit the rates by the growth and decline of “salting out” effect and surface tension. The benefits of combining these two processes were for the first time investigated from the aspect of promoting the intermediates degradation which were resistant in individual processes. UV caused a rapid transformation of ATZ to 2-hydroxyatrazine (OIET), which was insensitive to UV irradiation; however, US and USUV were able to degrade OIET and other intermediates through • OH attack. On the other hand, UV irradiation also could promote radical generation via H 2 O 2 decomposition, thereby resulting in less accumulation of more hydrophilic intermediates, which are difficult to degradation in the US process. Reaction pathways for ATZ degradation by all three processes are proposed. USUV achieved the greatest degree of ATZ mineralization with more than 60% TOC removed, contributed solely by the oxidation of side chains. Ammeline was found to be the only end-product in both US and USUV

Atrazine degradation using chemical-free process of USUV: Analysis of the micro-heterogeneous environments and the degradation mechanisms

Energy Technology Data Exchange (ETDEWEB)

Xu, L.J., E-mail: xulijie827@gmail.com [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Chu, W., E-mail: cewchu@polyu.edu.hk [Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Graham, Nigel, E-mail: n.graham@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

2014-06-30

Graphical abstract: - Highlights: • Two chemical-free AOP processes are combined to enhance atrazine degradation. • ATZ degradation in sonophotolytic process was analyzed using a previous proposed model. • The micro-bubble/liquid heterogeneous environments in sonolytic processes were investigated. • The salt effects on different sonolytic processes were examined. • ATZ degradation mechanisms were investigated and pathways were proposed. - Abstract: The effectiveness of sonolysis (US), photolysis (UV), and sonophotolysis (USUV) for the degradation of atrazine (ATZ) was investigated. An untypical kinetics analysis was found useful to describe the combined process, which is compatible to pseudo first-order kinetics. The heterogeneous environments of two different ultrasounds (20 and 400 kHz) were evaluated. The heterogeneous distribution of ATZ in the ultrasonic solution was found critical in determining the reaction rates at different frequencies. The presence of NaCl would promote/inhibit the rates by the growth and decline of “salting out” effect and surface tension. The benefits of combining these two processes were for the first time investigated from the aspect of promoting the intermediates degradation which were resistant in individual processes. UV caused a rapid transformation of ATZ to 2-hydroxyatrazine (OIET), which was insensitive to UV irradiation; however, US and USUV were able to degrade OIET and other intermediates through • OH attack. On the other hand, UV irradiation also could promote radical generation via H{sub 2}O{sub 2} decomposition, thereby resulting in less accumulation of more hydrophilic intermediates, which are difficult to degradation in the US process. Reaction pathways for ATZ degradation by all three processes are proposed. USUV achieved the greatest degree of ATZ mineralization with more than 60% TOC removed, contributed solely by the oxidation of side chains. Ammeline was found to be the only end-product in both US

Treatment of atrazine by integrating photocatalytic and biological processes

International Nuclear Information System (INIS)

Chan, C.Y.; Tao, S.; Dawson, R.; Wong, P.K.

2004-01-01

This research examines the degradation of atrazine by photocatalytic oxidation (PCO) under different experimental conditions. Deisopropylatrazine, deethylatrazine and deethyldeisopropylatrazine were formed as major intermediates based on gas chromatography-mass spectrometry. The reaction mixture was found to be toxic towards two bioassays, i.e. the Microtox[reg] and amphipods survival tests even when atrazine was completely degraded by PCO within 2 h under optimized conditions. The results indicate that adding H 2 O 2 could significantly enhance the degradation of atrazine by PCO. Ammeline, ammelide and cyanuric acid (CA) became the major intermediates/products as detected by high performance liquid chromatography from 6th to the 40th h of PCO treatment. After 72 h PCO treatment, only CA was detectable in the reaction mixture. Further degradation of CA was carried out by a newly isolated CA-degrading bacterium, Sphingomonas capsulata. The photochemical pretreatment integrated with microbial degradation lead to the complete degradation and detoxification of atrazine

Potential for isoproturon, atrazine and mecoprop to be degraded within a chalk aquifer system

Science.gov (United States)

Johnson, Andrew C.; White, Craig; Lal Bhardwaj, C.

2000-06-01

The potential for herbicide degradation in an unconfined chalk aquifer was examined by collecting and spiking fresh samples and incubating them in the laboratory. The microcosms were incubated at 20°C under aerobic conditions and spiked with either isoproturon, atrazine or mecoprop at a concentration of 100 μg/l. The samples were obtained from a single fieldsite within the Upper Chalk aquifer in Hampshire, UK. Groundwater samples required the presence of sterile chalk in a ratio of at least 1:13 to promote isoproturon degradation. An isoproturon degradation potential existed in the soil, and the chalk unsaturated and saturated zones. However, no degradation of isoproturon in the unsaturated zone was observed when a more appropriate simulation of in-situ moisture conditions was carried out. Apart from the soil, no potential for atrazine or mecoprop degradation could be detected in the same samples over a 200-day incubation. In a series of groundwater samples taken from different boreholes, 10-300 m apart, large differences in isoproturon degradation potential were observed. Removal rates for 100 μg/l isoproturon varied from 83-425 ng/day, but in some samples no degradation potential could be detected. The primary metabolite which could be distinguished from isoproturon degradation in chalk and groundwater was monodesmethyl-isoproturon. When a chalk groundwater sample was spiked with isoproturon at 0.9 μg/l, this was not degraded over a 300-day incubation period. Further experiments with fresh groundwater from a Triassic Sandstone site illustrated that groundwater bacteria could degrade isoproturon at the more realistic temperature of 10°C as well as at 20°C.

Evaluation of the the temperature and humidity effect in the Atrazine degradation in the Saldana soil (Tolima) for liquid chromatography of high resolution

International Nuclear Information System (INIS)

Acevedo Buitrago Baudilio; Guerrero Jairo A; Lozano Amanda; Fuentes Cilia

2000-01-01

In this study was designed an experiment under laboratory conditions with temperature and soil moisture controlled. The effect of these two factors was evaluated in atrazine degradation in silty loam soil, pH 6.23 (1:1 w), and 1.48% organic carbon. The extraction process of AT and deetilatrazine (DEA), and deisopropilatrazine (DIA) metabolites of the soil was carried out with methanol followed by a clean up with dichloromethane-buffer phosphate pH 10,0.01 M. Separation and quantification of the compounds was carried out by high performance liquid chromatography (HPLC). Soil moisture was not a significant factor in atrazine degradation process, while the temperature was the factor that regulates the herbicide degradation. Atrazine degradation at 30oC was faster than at 20o C. DIA and DEA metabolites were not detected in any soil field samples

Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles.

Science.gov (United States)

Brodeur, Julie C; Sassone, Alina; Hermida, Gladys N; Codugnello, Nadia

2013-06-01

Despite of the various studies reporting on the subject, anticipating the impacts of the widely-used herbicide atrazine on anuran tadpoles metamorphosis remains complex as increases or decreases of larval period duration are almost as frequently reported as an absence of effect. The aim of the present study was to examine the effects of environmentally-relevant concentrations of atrazine (0.1, 1, 10, 100, and 1000μg/L) on the timings of metamorphosis and body size at metamorphosis in the common South American toad, Rhinella arenarum (Anura: bufonidae). None of the atrazine concentrations tested significantly altered survival. Low atrazine concentrations in the range of 1-100μg/L were found to accelerate developmental rate in a non-monotonic U-shaped concentration-response relationship. This observed acceleration of the metamorphic process occurred entirely between stages 25 and 39; treated tadpoles proceeding through metamorphosis as control animals beyond this point. Together with proceeding through metamorphosis at a faster rate, tadpoles exposed to atrazine concentrations in the range of 1-100μg/L furthermore transformed into significantly larger metamorphs than controls, the concentration-response curve taking the form of an inverted U in this case. The no observed effect concentration (NOEC) was 0.1μg atrazine/L for both size at metamorphosis and timings of metamorphosis. Tadpoles exposed to 100μg/L 17β-estradiol presented the exact same alterations of developmental rate and body size as those treated with 1, 10 and 100μg/L of atrazine. Elements of the experimental design that facilitated the detection of alterations of metamorphosis at low concentrations of atrazine are discussed, together with the ecological significance of those findings. Copyright © 2013 Elsevier Inc. All rights reserved.

Isolation and characterization of atrazine mineralizing Bacillus subtilis strain HB-6.

Directory of Open Access Journals (Sweden)

Jinhua Wang

Full Text Available Atrazine is a widely used herbicide with great environmental concern due to its high potential to contaminate soil and waters. An atrazine-degrading bacterial strain HB-6 was isolated from industrial wastewater and the 16S rRNA gene sequencing identified HB-6 as a Bacillus subtilis. PCR assays indicated that HB-6 contained atrazine-degrading genes trzN, atzB and atzC. The strain HB-6 was capable of utilizing atrazine and cyanuric acid as a sole nitrogen source for growth and even cleaved the s-triazine ring and mineralized atrazine. The strain demonstrated a very high efficiency of atrazine biodegradation with a broad optimum pH and temperature ranges and could be enhanced by cooperating with other bacteria, suggesting its huge potential for remediation of atrazine-contaminated sites. To our knowledge, there are few Bacillus subtilis strains reported that can mineralize atrazine, therefore, the present work might provide some new insights on atrazine remediation.

Oxidative degradation of triazine- and sulfonylurea-based herbicides using Fe(VI): The case study of atrazine and iodosulfuron with kinetics and degradation products

Science.gov (United States)

The occurrence of common herbicides (Atrazine, ATZ and Iodosufuron, IDS), in waters presents potential risk to human and ecological health. The oxidative degradation of ATZ and IDS by ferrate(VI) (FeVIO42-, Fe(VI)) is studied at different pH levels where kinetically observed se...

Effect of Cell-to-matrix Ratio in Polyvinyl Alcohol Immobilized Pure and Mixed Cultures on Atrazine Degradation

International Nuclear Information System (INIS)

Siripattanakul, Sumana; Wirojanagud, Wanpen; McEvoy, John; Khan, Eakalak

2008-01-01

Atrazine biodegradation by immobilized pure and mixed cultures was examined. A pure atrazine-degrading culture, Agrobacterium radiobacter J14a (J14a), and a mixed culture (MC), isolated from an atrazine-contaminated crop field, were immobilized using phosphorylated-polyvinyl alcohol (PPVA). An existing cell immobilization procedure was modified to enhance PPVA matrix stability. The results showed that the matrices remained mechanically and chemically stable after shaking with glass beads over 15 days under various salt solutions and pH values. The immobilization process had a slight effect on cell viability. With the aid of scanning electron microscopy, a suitable microstructure of PPVA matrices for cell entrapment was observed. There were two porous layers of spherical gel matrices, the outside having an encapsulation property and the inside containing numerous pores for bacteria to occupy. J14a and MC were immobilized at three cell-to-matrix ratios of 3.5, 6.7, and 20 mg dry cells/mL matrix. The atrazine biodegradation tests were conducted in an aerobic batch system, which was inoculated with cells at 2,000 mg/L. The tests were also conducted using free (non-immobilized) J14a and MC for comparative purpose. The cell-to-matrix ratio of 3.5 mg/mL provided the highest atrazine removal efficiency of 40-50% in 120 h for both J14a and MC. The free cell systems, for both cultures, presented much lower atrazine removal efficiencies compared to the immobilized cell systems at the same level of inoculation

Uptake of C14-atrazine by prairie grasses in a phytoremediation setting.

Science.gov (United States)

Khrunyk, Yuliya; Schiewer, Silke; Carstens, Keri L; Hu, Dingfei; Coats, Joel R

2017-02-01

Agrochemicals significantly contribute to environmental pollution. In the USA, atrazine is a widely used pesticide and commonly found in rivers, water systems, and rural wells. Phytoremediation can be a cost-effective means of removing pesticides from soil. The objective of this project was to investigate the ability of prairie grasses to remove atrazine. 14 C-labeled atrazine was added to sterilized sand and water/nutrient cultures, and the analysis was performed after 21 days. Switchgrass and big bluestem were promising species for phytoremediation, taking up about 40% of the applied [ 14 C] in liquid hydroponic cultures, and between 20% and 33% in sand cultures. Yellow Indiangrass showed low resistance to atrazine toxicity and low uptake of [ 14 C] atrazine in liquid hydroponic cultures. Atrazine degradation increased progressively from sand to roots and leaves. Most atrazine taken up by prairie grasses from sand culture was degraded to metabolites, which accounted for 60-80% of [ 14 C] detected in leaves. Deisopropylatrazine (DIA) was the main metabolite detected in sand and roots, whereas in leaves further metabolism took place, forming increased amounts of didealkylatrazine (DDA) and an unidentified metabolite. In conclusion, prairie grasses achieved high atrazine removal and degradation, showing a high potential for phytoremediation.

Introduction of Atrazine-Degrading Pseudomonas SP. Strain ADP to Enhance Phytoremediation of Atrazine

Science.gov (United States)

Atrazine (ATR) has been widely applied in the US Midwestern states. Public health and ecological concerns have been raised about contamination of surface and ground water by ATR and its chlorinated metabolites, due to their toxicity and potential carcinogenic or endocrinology effects. Phytoremediati...

Assessing the phytoremediation potential of crop and grass plants for atrazine-spiked soils.

Science.gov (United States)

Sánchez, Virtudes; López-Bellido, Francisco Javier; Cañizares, Pablo; Rodríguez, Luis

2017-10-01

Pollution of soil and groundwater by atrazine has become an increasing environmental concern in the last decade. A phytoremediation test using plastic pots was conducted in order to assess the ability of several crops and grasses to remove atrazine from a soil of low permeability spiked with this herbicide. Four plant species were assessed for their ability to degrade or accumulate atrazine from soils: two grasses, i.e., ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea), and two crops, i.e., barley (Hordeum vulgare) and maize (Zea mays). Three different doses of atrazine were used for the contamination of the pots: 2, 5 and 10 mg kg -1 . 16 days after spiking, the initial amount of atrazine was reduced by 88.6-99.6% in planted pots, while a decrease of only 63.1-78.2% was found for the unplanted pots, thus showing the contribution of plants to soil decontamination. All the plant species were capable of accumulating atrazine and its N-dealkylated metabolites, i.e., deethylatrazine and deisopropylatrazine, in their tissues. Some toxic responses, such as biomass decreases and/or chlorosis, were observed in plants to a greater or lesser extent for initial soil doses of atrazine above 2 mg kg -1 . Maize was the plant species with the highest ability to accumulate atrazine derivatives, reaching up to 38.4% of the initial atrazine added to the soil. Rhizosphere degradation/mineralization by microorganisms or plant enzymes, together with degradation inside the plants, have been proposed as the mechanisms that contributed to a higher extent than plant accumulation to explain the removal of atrazine from soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phytoremediation potential of the novel atrazine tolerant Lolium multiflorum and studies on the mechanisms involved

International Nuclear Information System (INIS)

Merini, Luciano J.; Bobillo, Cecilia; Cuadrado, Virginia; Corach, Daniel; Giulietti, Ana M.

2009-01-01

Atrazine impact on human health and the environment have been extensively studied. Phytoremediation emerged as a low cost, environmental friendly biotechnological solution for atrazine pollution in soil and water. In vitro atrazine tolerance assays were performed and Lolium multiflorum was found as a novel tolerant species, able to germinate and grow in the presence of 1 mg kg -1 of the herbicide. L. multiflorum presented 20% higher atrazine removal capacity than the natural attenuation, with high initial degradation rate in microcosms. The mechanisms involved in atrazine tolerance such as mutation in psbA gene, enzymatic detoxification via P 450 or chemical hydrolysis through benzoxazinones were evaluated. It was demonstrated that atrazine tolerance is conferred by enhanced enzymatic detoxification via P 450 . Due to its atrazine degradation capacity in soil and its agronomical properties, L. multiflorum is a candidate for designing phytoremediation strategies for atrazine contaminated agricultural soils, especially those involving run-off avoiding. - Finding of a novel atrazine-tolerant species, as a potential candidate for phytoremediating herbicide-contaminated agriculture soils and elucidation of the mechanisms involved in tolerance.

Phytoremediation potential of the novel atrazine tolerant Lolium multiflorum and studies on the mechanisms involved

Energy Technology Data Exchange (ETDEWEB)

Merini, Luciano J. [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina); Bobillo, Cecilia [Servicio de Huellas Digitales Geneticas, Facultad de Farmacia y Bioquimica, Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires, Junin 956, BS As (Argentina); Cuadrado, Virginia [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina); Corach, Daniel [Servicio de Huellas Digitales Geneticas, Facultad de Farmacia y Bioquimica, Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires, Junin 956, BS As (Argentina); Giulietti, Ana M., E-mail: agiule@ffyb.uba.a [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina)

2009-11-15

Atrazine impact on human health and the environment have been extensively studied. Phytoremediation emerged as a low cost, environmental friendly biotechnological solution for atrazine pollution in soil and water. In vitro atrazine tolerance assays were performed and Lolium multiflorum was found as a novel tolerant species, able to germinate and grow in the presence of 1 mg kg{sup -1} of the herbicide. L. multiflorum presented 20% higher atrazine removal capacity than the natural attenuation, with high initial degradation rate in microcosms. The mechanisms involved in atrazine tolerance such as mutation in psbA gene, enzymatic detoxification via P{sub 450} or chemical hydrolysis through benzoxazinones were evaluated. It was demonstrated that atrazine tolerance is conferred by enhanced enzymatic detoxification via P{sub 450}. Due to its atrazine degradation capacity in soil and its agronomical properties, L. multiflorum is a candidate for designing phytoremediation strategies for atrazine contaminated agricultural soils, especially those involving run-off avoiding. - Finding of a novel atrazine-tolerant species, as a potential candidate for phytoremediating herbicide-contaminated agriculture soils and elucidation of the mechanisms involved in tolerance.

New aspects on atrazine biodegradation

Directory of Open Access Journals (Sweden)

Luciane Sene

2010-04-01

Full Text Available The world practice of using agrochemicals for long periods, in an indiscriminated and abusive way, has been a concern of the authorities involved in public health and sustainability of the natural resources, as a consequence of environmental contamination. Agrochemicals refer to a broad range of insecticides, fungicides and herbicides, and among them stands out atrazine, a herbicide intensively used in sugarcane, corn and sorghum cultures, among others. Researches have demonstrated that atrazine has toxic effects in algae, aquatic plants, aquatic insects, fishes and mammals. Due to the toxicity and persistence of atrazine in the environment, the search of microbial strains capable of degrading it is fundamental to the development of bioremediation processes, as corrective tools to solve the current problems of the irrational use of agrochemicals. This review relates the main microbial aspects and research on atrazine degradation by isolated microbial species and microbial consortia, as well as approaches on the development of techniques for microbial removal of atrazine in natural environments.A prática mundial do uso de agroquímicos por períodos extensos, de maneira indiscriminada e abusiva, tem mobilizado as autoridades envolvidas em saúde pública e sustentabilidade de fontes naturais, como uma conseqüência da contaminação ambiental. Agroquímicos referem-se a uma ampla variedade de inseticidas, fungicidas e herbicidas, entre estes a atrazina, um herbicida intensivamente usado em culturas de cana-de-açúcar, milho, sorgo, entre outros. Pesquisadores têm demonstrado que a atrazina tem efeitos tóxicos em algas, plantas aquáticas, insetos aquáticos, peixes e mamíferos. Devido à toxicidade e à persistência da atrazina no ambiente, a busca de linhagens microbianas capazes de degradá-la é fundamental para o desenvolvimento de processos de biorremediação, com uma ferramenta corretiva para solucionar problemas decorridos do uso

Monitoring bioremediation of atrazine in soil microcosms using molecular tools

International Nuclear Information System (INIS)

Sagarkar, Sneha; Mukherjee, Shinjini; Nousiainen, Aura; Björklöf, Katarina; Purohit, Hemant J.; Jørgensen, Kirsten S.; Kapley, Atya

2013-01-01

Molecular tools in microbial community analysis give access to information on catabolic potential and diversity of microbes. Applied in bioremediation, they could provide a new dimension to improve pollution control. This concept has been demonstrated in the study using atrazine as model pollutant. Bioremediation of the herbicide, atrazine, was analyzed in microcosm studies by bioaugmentation, biostimulation and natural attenuation. Genes from the atrazine degrading pathway atzA/B/C/D/E/F, trzN, and trzD were monitored during the course of treatment and results demonstrated variation in atzC, trzD and trzN genes with time. Change in copy number of trzN gene under different treatment processes was demonstrated by real-time PCR. The amplified trzN gene was cloned and sequence data showed homology to genes reported in Arthrobacter and Nocardioides. Results demonstrate that specific target genes can be monitored, quantified and correlated to degradation analysis which would help in predicting the outcome of any bioremediation strategy. - Highlights: ► Degradation of herbicide, atrazine. ► Comparison of bioremediation via bioaugmentation, biostimulation and natural attenuation. ► Gene profile analysis in all treatments. ► Variation in trzN gene numbers correlated to degradation efficiency. ► Cloning and sequence analysis of trzN gene demonstrates very high homology to reported gene. - This study demonstrates the use of molecular tools in bioremediation to monitor and track target genes; correlates the results with degradation and thereby predicts the efficiency of treatment.

Spatial variability of atrazine dissipation in an allophanic soil.

Science.gov (United States)

Müller, Karin; Smith, Roger E; James, Trevor K; Holland, Patrick T; Rahman, Anis

2003-08-01

The small-scale variability (0.5 m) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) concentrations and soil water contents in a volcanic silt loam soil (Haplic Andosol, FAO system) was studied in an area of 0.1 ha. Descriptive and spatial statistics were used to analyse the data. On average we recovered 102% of the applied atrazine 2 h after the herbicide application (CV = 35%). An increase in the CV of the concentrations with depth could be ascribed to a combination of extrinsic and intrinsic factors. Both variables, atrazine concentrations and soil water content, showed a high horizontal variability. The semivariograms of the atrazine concentrations exhibited the pure nugget effect, no pattern could be determined along the 15.5-m long transects on any of the seven sampling days over a 55-day period. Soil water content had a weak spatial autocorrelation with a range of 6-10 m. The dissipation of atrazine analysed using a high vertical sampling resolution of 0.02 m to 0.2 m showed that 70% of the applied atrazine persisted in the upper 0.02-m layer of the soil for 12 days. After 55 days and 410 mm of rainfall the centre of the pesticide mass was still at a soil depth of 0.021 m. The special characteristics of the soil (high organic carbon content, allophanic clay) had a strong influence on atrazine sorption and mobility. The mass recovery after 55 days was low. The laboratory degradation rate for atrazine, determined in a complementary incubation study and corrected for the actual field temperature using the Arrhenius equation, only accounted for about 35% of the losses that occurred in the field. Results suggest field degradation rates to be more changeable in time and much faster than under controlled conditions. Preferential flow is discussed as a component of the field transport process.

Modeling atrazine transport in soil columns with HYDRUS-1D

Directory of Open Access Journals (Sweden)

John Leju Celestino Ladu

2011-09-01

Full Text Available Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS-1D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves (BTCs. Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.

Magnetic bionanoparticles of Penicillium sp. yz11-22N2 doped with Fe3O4 and encapsulated within PVA-SA gel beads for atrazine removal.

Science.gov (United States)

Yu, Jiaping; He, Huijun; Yang, William L; Yang, Chunping; Zeng, Guangming; Wu, Xin

2018-07-01

A novel magnetic bionanomaterial, Penicillium sp. yz11-22N2 doped with nano Fe 3 O 4 entrapped in polyvinyl alcohol-sodium alginate gel beads (PFEPS), was successfully synthesized. The factors including nutrient substance, temperature, pH, initial concentrations of atrazine and rotational speeds were presented and discussed in detail. Results showed that the highest removal efficiency of atrazine by PFEPS was 91.2% at 8.00 mg/L atrazine. The maximum removal capacity for atrazine was 7.94 mg/g. Meanwhile, it has been found that most of atrazine were removed by metabolism and degradation of Penicillium sp. yz11-22N2, which could use atrazine as the sole source of either carbon or nitrogen. Degradation kinetics of atrazine conformed to first-order kinetics model. The intermediates indicated that the possible pathway for atrazine degradation by PFEPS mainly included hydrolysis dechlorination, dealkylation, side-chain oxidation and ring-opening. Copyright © 2018 Elsevier Ltd. All rights reserved.

Quantitative accelerated degradation testing: Practical approaches

International Nuclear Information System (INIS)

Mohammadian, S. Hossein; Ait-Kadi, Daoud; Routhier, Francois

2010-01-01

The concept of accelerated testing by tracking degradation of samples over test time needs to be developed for reliability estimation. This paper aims at proposing practical approaches to conduct accelerated degradation testing on new and available used samples. For this purpose, product failure is related to a suitable physical property. Then, its failure time is defined as the expected time in which its property reaches the critical level. Degradation model of field samples returned from service due to a degrading failure mode has been estimated based on the least square method, and available gap between manufacturer criterion and user's claim (to report a failure) has also been discussed. For a product under some stresses, a general formula has been proposed by the superposition principle in order to estimate its degradation for independent and dependent failure modes. If used samples are available, and acceleration factor of the related test is unknown, partial aging method has been presented to considerably shorten the test time.

Determination of the atrazine migration parameters in Vertisol

Science.gov (United States)

Raymundo-Raymundo, E.; Hernandez-Vargas, J.; Nikol'Skii, Yu. N.; Guber, A. K.; Gavi-Reyes, F.; Prado-Pano, B. L.; Figueroa-Sandoval, B.; Mendosa-Hernandez, J. R.

2010-05-01

The parameters of the atrazine migration in columns with undisturbed Vertisol sampled from an irrigated plot in Guanajuato, Mexico were determined. A model of the convection-dispersion transport of the chemical compounds accounting for the decomposition and equilibrium adsorption, which is widely applied for assessing the risk of contamination of natural waters with pesticides, was used. The model parameters were obtained by solving the inverse problem of the transport equation on the basis of laboratory experiments on the transport of the 18O isotope and atrazine in soil columns with an undisturbed structure at three filtration velocities. The model adequately described the experimental data at the individual selection of the parameters for each output curve. Physically unsubstantiated parameters of the atrazine adsorption and degradation were obtained when the parameter of the hydrodynamic dispersion was determined from the data on the 18O migration. The simulation also showed that the use of parameters obtained at water content close to saturation in the calculations for an unsaturated soil resulted in the overestimation of the leaching rate and the maximum concentration of atrazine in the output curve compared to the experimental data.

Persistence of 14C-labeled atrazine and its residues in a field lysimeter soil after 22 years

International Nuclear Information System (INIS)

Jablonowski, Nicolai D.; Koeppchen, Stephan; Hofmann, Diana; Schaeffer, Andreas; Burauel, Peter

2009-01-01

Twenty-two years after the last application of ring- 14 C-labeled atrazine at customary rate (1.7 kg ha -1 ) on an agriculturally used outdoor lysimeter, atrazine is still detectable by means of accelerated solvent extraction and LC-MS/MS analysis. Extractions of the 0-10 cm soil layer yielded 60% of the residual 14 C-activity. The extracts contained atrazine (1.0 μg kg -1 ) and 2-hydroxy-atrazine (42.5 μg kg -1 ). Extractions of the material of the lowest layer 55-60 cm consisting of fine gravel yielded 93% of residual 14 C-activity, of which 3.4 μg kg -1 was detected as atrazine and 17.7 μg kg -1 was 2-hydroxy-atrazine. The detection of atrazine in the lowest layer was of almost four times higher mass than in the upper soil layer. These findings highlight the fact that atrazine is unexpectedly persistent in soil. The overall persistence of atrazine in the environment might represent a potential risk for successive groundwater contamination by leaching even after 22 years of environmental exposure. - Atrazine and its metabolite 2-hydroxy-atrazine are still present in soil after long-term aging.

Performance of a novel microwave-based treatment technology for atrazine removal and destruction: Sorbent reusability and chemical stability, and effect of water matrices

International Nuclear Information System (INIS)

Hu, Erdan; Hu, Yuanan; Cheng, Hefa

2015-01-01

Highlights: • Cu"2"+ and Fe"3"+ in zeolite pores enhance atrazine sorption and MW-induced degradation. • Exchanged zeolites perform well over multiple sorption–regeneration cycles. • Fe"3"+ species in the zeolite micropores have much greater stability than those of Cu"2"+. • DOC in natural waters can compromise the sorption capacity of exchanged zeolites. • Iron-exchanged dealuminated Y zeolites hold great promise for practical applications. - Abstract: Transition metal-exchanged dealuminated Y zeolites were used to adsorb atrazine from aqueous solutions, followed by regeneration of the sorbents and destruction of the sorbed atrazine with microwave irradiation. Exchange of copper and iron into the zeolite's micropores significantly enhanced its sorption capacity and selectivity toward atrazine, and increased the microwave-induced degradation rate of the sorbed atrazine by 3–4-folds. Both the copper- and iron-exchanged zeolites could be regenerated and reused multiple times, while the catalytic activity of the latter was more robust due to the much greater chemical stability of Fe"3"+ species in the micropores. The presence of humic acid, and common cations and anions had little impact on the sorption of atrazine on the transition metal-exchanged zeolites. In the treatment of atrazine spiked in natural surface water and groundwater samples, sorptive removal of atrazine was found to be impacted by the level of dissolved organic carbon, probably through competition for the micropore spaces and pore blocking, while the water matrices exhibited no strong effect on the microwave-induced degradation of sorbed atrazine. Overall, iron-exchanged dealuminated Y zeolites show great potential for removal and destruction of atrazine from contaminated surface water and groundwater in practical implementation of the novel treatment technology.

Performance of a novel microwave-based treatment technology for atrazine removal and destruction: Sorbent reusability and chemical stability, and effect of water matrices

Energy Technology Data Exchange (ETDEWEB)

Hu, Erdan; Hu, Yuanan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Cheng, Hefa, E-mail: hefac@umich.edu [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

2015-12-15

Highlights: • Cu{sup 2+} and Fe{sup 3+} in zeolite pores enhance atrazine sorption and MW-induced degradation. • Exchanged zeolites perform well over multiple sorption–regeneration cycles. • Fe{sup 3+} species in the zeolite micropores have much greater stability than those of Cu{sup 2+}. • DOC in natural waters can compromise the sorption capacity of exchanged zeolites. • Iron-exchanged dealuminated Y zeolites hold great promise for practical applications. - Abstract: Transition metal-exchanged dealuminated Y zeolites were used to adsorb atrazine from aqueous solutions, followed by regeneration of the sorbents and destruction of the sorbed atrazine with microwave irradiation. Exchange of copper and iron into the zeolite's micropores significantly enhanced its sorption capacity and selectivity toward atrazine, and increased the microwave-induced degradation rate of the sorbed atrazine by 3–4-folds. Both the copper- and iron-exchanged zeolites could be regenerated and reused multiple times, while the catalytic activity of the latter was more robust due to the much greater chemical stability of Fe{sup 3+} species in the micropores. The presence of humic acid, and common cations and anions had little impact on the sorption of atrazine on the transition metal-exchanged zeolites. In the treatment of atrazine spiked in natural surface water and groundwater samples, sorptive removal of atrazine was found to be impacted by the level of dissolved organic carbon, probably through competition for the micropore spaces and pore blocking, while the water matrices exhibited no strong effect on the microwave-induced degradation of sorbed atrazine. Overall, iron-exchanged dealuminated Y zeolites show great potential for removal and destruction of atrazine from contaminated surface water and groundwater in practical implementation of the novel treatment technology.

Flow accelerated organic coating degradation

Science.gov (United States)

Zhou, Qixin

Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as

Dissipation of atrazine, enrofloxacin, and sulfamethazine in wood chip bioreactors and impact on denitrification

Science.gov (United States)

Wood chip bioreactors are receiving increasing attention as a means of reducing nitrate in subsurface tile drainage systems. Agrochemicals in tile drainage water entering wood chip bioreactors can be retained or degraded and may impact denitrification. The degradation of 5 mg L-1 atrazine, enrofloxa...

Accelerated Testing Of Photothermal Degradation Of Polymers

Science.gov (United States)

Kim, Soon Sam; Liang, Ranty Hing; Tsay, Fun-Dow

1989-01-01

Electron-spin-resonance (ESR) spectroscopy and Arrhenius plots used to determine maximum safe temperature for accelerated testing of photothermal degradation of polymers. Aging accelerated by increasing illumination, temperature, or both. Results of aging tests at temperatures higher than those encountered in normal use valid as long as mechanism of degradation same throughout range of temperatures. Transition between different mechanisms at some temperature identified via transition between activation energies, manifesting itself as change in slope of Arrhenius plot at that temperature.

Regression models for estimating concentrations of atrazine plus deethylatrazine in shallow groundwater in agricultural areas of the United States

Science.gov (United States)

Stackelberg, Paul E.; Barbash, Jack E.; Gilliom, Robert J.; Stone, Wesley W.; Wolock, David M.

2012-01-01

Tobit regression models were developed to predict the summed concentration of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and its degradate deethylatrazine [6-chloro-N-(1-methylethyl)-1,3,5,-triazine-2,4-diamine] (DEA) in shallow groundwater underlying agricultural settings across the conterminous United States. The models were developed from atrazine and DEA concentrations in samples from 1298 wells and explanatory variables that represent the source of atrazine and various aspects of the transport and fate of atrazine and DEA in the subsurface. One advantage of these newly developed models over previous national regression models is that they predict concentrations (rather than detection frequency), which can be compared with water quality benchmarks. Model results indicate that variability in the concentration of atrazine residues (atrazine plus DEA) in groundwater underlying agricultural areas is more strongly controlled by the history of atrazine use in relation to the timing of recharge (groundwater age) than by processes that control the dispersion, adsorption, or degradation of these compounds in the saturated zone. Current (1990s) atrazine use was found to be a weak explanatory variable, perhaps because it does not represent the use of atrazine at the time of recharge of the sampled groundwater and because the likelihood that these compounds will reach the water table is affected by other factors operating within the unsaturated zone, such as soil characteristics, artificial drainage, and water movement. Results show that only about 5% of agricultural areas have greater than a 10% probability of exceeding the USEPA maximum contaminant level of 3.0 μg L-1. These models are not developed for regulatory purposes but rather can be used to (i) identify areas of potential concern, (ii) provide conservative estimates of the concentrations of atrazine residues in deeper potential drinking water supplies, and (iii) set priorities

A General Accelerated Degradation Model Based on the Wiener Process.

Science.gov (United States)

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-12-06

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A General Accelerated Degradation Model Based on the Wiener Process

Directory of Open Access Journals (Sweden)

Le Liu

2016-12-01

Full Text Available Accelerated degradation testing (ADT is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

Simulation of branched serial first-order decay of atrazine and metabolites in adapted and nonadapted soils

Science.gov (United States)

Webb, Richard M.; Sandstrom, Mark W.; Jason L. Krutz,; Dale L. Shaner,

2011-01-01

In the present study a branched serial first-order decay (BSFOD) model is presented and used to derive transformation rates describing the decay of a common herbicide, atrazine, and its metabolites observed in unsaturated soils adapted to previous atrazine applications and in soils with no history of atrazine applications. Calibration of BSFOD models for soils throughout the country can reduce the uncertainty, relative to that of traditional models, in predicting the fate and transport of pesticides and their metabolites and thus support improved agricultural management schemes for reducing threats to the environment. Results from application of the BSFOD model to better understand the degradation of atrazine supports two previously reported conclusions: atrazine (6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine) and its primary metabolites are less persistent in adapted soils than in nonadapted soils; and hydroxyatrazine was the dominant primary metabolite in most of the soils tested. In addition, a method to simulate BSFOD in a one-dimensional solute-transport unsaturated zone model is also presented.

Effects of Atrazine on Soil Microorganisms

Directory of Open Access Journals (Sweden)

Ljiljana Radivojević

2006-01-01

Full Text Available Effects of the herbicide atrazine on soil microorganisms was investigated. Trials were set up in laboratory, on a clay loam soil. Atrazine was applied at 8.0, 40.0 and 80.0 mg/kg soil rates. The abundance of total microorganisms, fungi, actinomycetes, cellulolytic microorganisms and amino-heterotrophs was recorded. Soil samples were collected 1, 7, 14, 21, 30 and 60 days after atrazine treatment for microbiological analyses.The results showed that the intensity of atrazine effect on soil microorganisms depended on treatment rate, exposure time and group of microorganisms. Atrazine had an inhibiting effect on cellulolytic microorganisms and amino-heterotrophs. Initially, it inhibited fungiand actinomycetes but its effect turned into a stimulating one once a population recovered. Atrazine had a stimulating effect on total abundance of microorganisms.

Atrazine removal in Danish anaerobic aquifers

DEFF Research Database (Denmark)

Pedersen, Philip Grinder; Arildskov, N.P.; Albrechtsen, Hans-Jørgen

2002-01-01

process was abiotic since atrazine was also removed from microbially inhibited autoclaved and chloroform amended controls, although in controls amended with mercury, atrazine removal was slowed down. (ring-U-C-14)- atrazine amended samples showed no mineralization to (CO2)-C-14 or transformation...

Hydroponic Uptake of Atrazine and Lambda-cyhalothrin in Aquatic Macrophytes

Science.gov (United States)

Bouldin, J. L.; Farris, J. L.; Moore, M. T.; Smith, S.; Cooper, C. M.

2005-05-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to soil geochemical modifications and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48 h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8 d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that the seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Evaluation of Crops Sensitivity to Atrazine Soil Residual

Directory of Open Access Journals (Sweden)

E Izadi

2012-02-01

Full Text Available Abstract In order to study the sensitivity of 9 crops to atrazine soil residual, two separate experiments were conducted in field and greenhouse conditions. First experiment was conducted in a field with treated soil by atrazine based on split plot and the results evaluated in greenhouse conditions. Treatments in the field experiment included two organic manure application rates (0 and 50 t/ha as main plots and 2 atrazine application rates (2 and 4 kg/ha atrazine a.i. as sob plots. After corn harvesting soil was sampled at 0-15 cm surface layer in each plots in 15 points, after mixing the samples. Wheat, barley, sugar beet, pea, lens and colza planted in pots at greenhouse. Second experiment conducted in greenhouse conditions for evaluation of atrazine soil residual in completely randomized design. Treatments included atrazine soil residual concentrations (0, 0.2, 0.5, 1, 5, 10 and 15 mg/kg soil and crops included wheat, barley, sugar beet, pea, lens, rape, bean and tomato. Results showed that atrazine residue had no effect on crops growth in field experiment treated with atrazine. It seems that atrazine residue in filed soil is lower that its damage threshold for crops or maybe for its fast removal in field than in control conditions. But in bioassay experiment (greenhouse experiment crops response to atrazine residues were different. Results showed that onion and pea were most susceptible ant tolerant crops between studied species and based of ED50 parameter the other crops tolerance to total residue ranked as: pea< bean< lentil< sugar beet< tomato< barley< wheat< rape< onion. Keywords: Atrazine residue, Pea, Bean, Lentil, Sugar beet, Barley, Wheat, Rape, Tomato

Effect of arbuscular mycorrhizal fungus (Glomus caledonium) on the accumulation and metabolism of atrazine in maize (Zea mays L.) and atrazine dissipation in soil

Energy Technology Data Exchange (ETDEWEB)

Huang Honglin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18th Shuangqinglu, Haidian District, Beijing 100085 (China); Zhang Shuzhen [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18th Shuangqinglu, Haidian District, Beijing 100085 (China)]. E-mail: szzhang@mail.rcees.ac.cn; Shan Xiaoquan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18th Shuangqinglu, Haidian District, Beijing 100085 (China); Chen Baodong [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18th Shuangqinglu, Haidian District, Beijing 100085 (China); Zhu Yongguan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18th Shuangqinglu, Haidian District, Beijing 100085 (China); Bell, J. Nigel B. [Center for Environmental Policy, Imperial College, London (United Kingdom)

2007-03-15

Effects of an arbuscular mycorrhizal (AM) fungus (Glomus caledonium) on accumulation and metabolism of atrazine in maize grown in soil contaminated with different concentrations of atrazine were investigated in a series of pot experiments. Roots of mycorrhizal plants accumulated more atrazine than non-mycorrhizal roots. In contrast, atrazine accumulation in shoot decreased in mycorrhizal compared with non-mycorrhizal plants. No atrazine derivatives were detected in the soil, either with or without mycorrhizal colonization. However, atrazine metabolites, deethylatrazine (DEA) and deisopropylatrazine (DIA), were detected in plant roots and the AM colonization enhanced the metabolism. After plant harvest atrazine concentrations decreased markedly in the soils compared to the initial concentrations. The decreases were the most in rhizosphere soil and then near-rhizosphere soil and the least in bulk soil. Mycorrhizal treatment enhanced atrazine dissipation in the near-rhizosphere and bulk soils irrespective of atrazine application rates. - Arbuscular mycorrhizal fungus increases the accumulation and metabolism of atrazine in maize.

Effect of arbuscular mycorrhizal fungus (Glomus caledonium) on the accumulation and metabolism of atrazine in maize (Zea mays L.) and atrazine dissipation in soil

International Nuclear Information System (INIS)

Huang Honglin; Zhang Shuzhen; Shan Xiaoquan; Chen Baodong; Zhu Yongguan; Bell, J. Nigel B.

2007-01-01

Effects of an arbuscular mycorrhizal (AM) fungus (Glomus caledonium) on accumulation and metabolism of atrazine in maize grown in soil contaminated with different concentrations of atrazine were investigated in a series of pot experiments. Roots of mycorrhizal plants accumulated more atrazine than non-mycorrhizal roots. In contrast, atrazine accumulation in shoot decreased in mycorrhizal compared with non-mycorrhizal plants. No atrazine derivatives were detected in the soil, either with or without mycorrhizal colonization. However, atrazine metabolites, deethylatrazine (DEA) and deisopropylatrazine (DIA), were detected in plant roots and the AM colonization enhanced the metabolism. After plant harvest atrazine concentrations decreased markedly in the soils compared to the initial concentrations. The decreases were the most in rhizosphere soil and then near-rhizosphere soil and the least in bulk soil. Mycorrhizal treatment enhanced atrazine dissipation in the near-rhizosphere and bulk soils irrespective of atrazine application rates. - Arbuscular mycorrhizal fungus increases the accumulation and metabolism of atrazine in maize

Concentrated Light for Accelerated Photo Degradation of Polymer Materials

DEFF Research Database (Denmark)

Madsen, Morten Vesterager; Tromholt, Thomas; Norrman, Kion

2013-01-01

Concentrated light is used to perform photochemical degradation of polymer solar cell materials with acceleration factors up to 1200. At constant temperature the photon efficiency in regards to photo degradation is constant for 1–150 suns and oxygen diffusion rates are not a limiting factor...

Label-free impedimetric immunosensor for sensitive detection of atrazine

Energy Technology Data Exchange (ETDEWEB)

Ionescu, Rodica E. [Universite de Lyon, Laboratoire de Sciences Analytiques, UMR CNRS 5180, Universite Claude Bernard Lyon 1, Batiment CPE, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Gondran, Chantal; Bouffier, Laurent [Departement de Chimie Moleculaire, UMR CNRS 5250, ICMG FR CNRS 2607, Universite Joseph Fourier, BP 53, 38041 Grenoble, Cedex 9 (France); Jaffrezic-Renault, Nicole, E-mail: nicole.jaffrezic@univ-lyon1.f [Universite de Lyon, Laboratoire de Sciences Analytiques, UMR CNRS 5180, Universite Claude Bernard Lyon 1, Batiment CPE, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Martelet, Claude [Universite de Lyon, Laboratoire de Sciences Analytiques, UMR CNRS 5180, Universite Claude Bernard Lyon 1, Batiment CPE, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Cosnier, Serge, E-mail: serge.cosnier@ujf-grenoble.f [Departement de Chimie Moleculaire, UMR CNRS 5250, ICMG FR CNRS 2607, Universite Joseph Fourier, BP 53, 38041 Grenoble, Cedex 9 (France)

2010-08-30

Impedance spectroscopy transduction combined with the immunosensor technology has been used for the determination of atrazine, a herbicide The sensor electrode was based on the immobilization of anti-atrazine antibody by affinity binding onto a polypyrrole film N-substituted by nitrilotriacetic acid NTA electrogenerated on a gold electrode. The poly NTA film was previously modified by the coordination of Cu2 ions by the chelating NTA centers. The anti-atrazine antibody Fab fragment K47 modified with histidine-tag was then anchored by affinity interactions between the histidine-tag and the coordinated Cu2. Cyclic voltammetry experiments confirm that the antibody immobilization and the resulting immunosensor were applied to the impedimetric detection of atrazine without reagent and labelling step. The immunoreaction of atrazine on the attached anti-atrazine antibody directly triggers an increase in the charge transfer resistance proportional to the atrazine concentration, allowing the detection of extremely low atrazine concentration, namely 10 pg mL{sup -1}.

Study of the Bioremediation of Atrazine under Variable Carbon and Nitrogen Sources by Mixed Bacterial Consortium Isolated from Corn Field Soil in Fars Province of Iran

Science.gov (United States)

Nasseri, Simin; Hashemi, Hassan

2013-01-01

Atrazine herbicide that is widely used in corn production is frequently detected in water resources. The main objectives of this research were focused on assessing the effects of carbon and nitrogen sources on atrazine biodegradation by mixed bacterial consortium and by evaluating the feasibility of using mixed bacterial consortium in soil culture. Shiraz corn field soil with a long history of atrazine application has been explored for their potential of atrazine biodegradation. The influence of different carbon compounds and the effect of nitrogen sources and a different pH (5.5–8.5) on atrazine removal efficiency by mixed bacterial consortium in liquid culture were investigated. Sodium citrate and sucrose had the highest atrazine biodegradation rate (87.22%) among different carbon sources. Atrazine biodegradation rate decreased more quickly by the addition of urea (26.76%) compared to ammonium nitrate. Based on the data obtained in this study, pH of 7.0 is optimum for atrazine biodegradation. After 30 days of incubation, the percent of atrazine reduction rates were significantly enhanced in the inoculated soils (60.5%) as compared to uninoculated control soils (12%) at the soil moisture content of 25%. In conclusion, bioaugmentation of soil with mixed bacterial consortium may enhance the rate of atrazine degradation in a highly polluted soil. PMID:23533452

Biodegradation of a commercial mixture of the herbicides atrazine and S-metolachlor in a multi-channel packed biofilm reactor.

Science.gov (United States)

Cabrera-Orozco, Alberto; Galíndez-Nájera, Silvia Patricia; Ruiz-Ordaz, Nora; Galíndez-Mayer, Juvencio; Martínez-Jerónimo, Fernando

2017-11-01

Atrazine and S-metolachlor are two of the most widely used herbicides for agricultural purposes; consequently, residues of both compounds and their metabolites had been detected in ground and superficial waters. Unlike atrazine, the complete degradation of metolachlor has not been achieved. Hence, the purpose of this research is to study the biodegradation of a commercial mixture of atrazine and S-metolachlor in a prototype of a multi-channel packed-bed-biofilm reactor (MC-PBR) designed with the aim of solving the problems of pressure drop and oxygen transfer, typically found on this type of bioreactors.Because the removal efficiency of the herbicides was increased when Candida tropicalis was added to the original microbial community isolated, the reactor was inoculated with this enriched community. The operational conditions tested in batch and continuous mode did not affect the removal efficiency of atrazine; however, this was not the case for S-metolachlor. The removal rates and efficiencies showed a notable variation along the MC-PBR operation.

Study of the Bioremediation of Atrazine under Variable Carbon and Nitrogen Sources by Mixed Bacterial Consortium Isolated from Corn Field Soil in Fars Province of Iran

Directory of Open Access Journals (Sweden)

Mansooreh Dehghani

2013-01-01

Full Text Available Atrazine herbicide that is widely used in corn production is frequently detected in water resources. The main objectives of this research were focused on assessing the effects of carbon and nitrogen sources on atrazine biodegradation by mixed bacterial consortium and by evaluating the feasibility of using mixed bacterial consortium in soil culture. Shiraz corn field soil with a long history of atrazine application has been explored for their potential of atrazine biodegradation. The influence of different carbon compounds and the effect of nitrogen sources and a different pH (5.5–8.5 on atrazine removal efficiency by mixed bacterial consortium in liquid culture were investigated. Sodium citrate and sucrose had the highest atrazine biodegradation rate (87.22% among different carbon sources. Atrazine biodegradation rate decreased more quickly by the addition of urea (26.76% compared to ammonium nitrate. Based on the data obtained in this study, pH of 7.0 is optimum for atrazine biodegradation. After 30 days of incubation, the percent of atrazine reduction rates were significantly enhanced in the inoculated soils (60.5% as compared to uninoculated control soils (12% at the soil moisture content of 25%. In conclusion, bioaugmentation of soil with mixed bacterial consortium may enhance the rate of atrazine degradation in a highly polluted soil.

Toxicity Assessment of Atrazine and Related Triazine Compounds in the Microtox Assay, and Computational Modeling for Their Structure-Activity Relationship

Directory of Open Access Journals (Sweden)

Jerzy Leszczynski

2000-10-01

Full Text Available The triazines are a group of chemically similar herbicides including atrazine, cyanazine, and propazine, primarily used to control broadleaf weeds. About 64 to 80 million lbs of atrazine alone are used each year in the United States, making it one of the two most widely used pesticides in the country. All triazines are somewhat persistent in water and mobile in soil. They are among the most frequently detected pesticides in groundwater. They are considered as possible human carcinogens (Group C based on an increase in mammary gland tumors in female laboratory animals. In this research, we performed the Microtox Assay to investigate the acute toxicity of a significant number of triazines including atrazine, atraton, ametryne, bladex, prometryne, and propazine, and some of their degradation products including atrazine desethyl, atrazine deisopropyl, and didealkyled triazine. Tests were carried out as described by Azur Environmental [1]. The procedure measured the relative acute toxicity of triazines, producing data for the calculation of triazine concentrations effecting 50% reduction in bioluminescence (EC50s. Quantitative structure-activity relationships (QSAR were examined based on the molecular properties obtained from quantum mechanical predictions performed for each compound. Toxicity tests yielded EC50 values of 39.87, 273.20, 226.80, 36.96, 81.86, 82.68, 12.74, 11.80, and 78.50 mg/L for atrazine, propazine, prometryne, atraton, atrazine desethyl, atrazine deisopropyl, didealkylated triazine, ametryne, and bladex, respectively; indicating that ametryne was the most toxic chemical while propazine was the least toxic. QSAR evaluation resulted in a coefficient of determination (r2 of 0.86, indicating a good value of toxicity prediction based on the chemical structures/properties of tested triazines.

Accelerated Testing of UH-60 Viscous Bearings for Degraded Grease Fault

Science.gov (United States)

Dykas, Brian; Hood, Adrian; Krantz, Timothy; Klemmer, Marko

2015-01-01

An accelerated aging investigation of critical aviation bearings lubricated with MIL-PRF- 81322 grease was conducted to derive an understanding of the mechanisms of grease degradation and loss of lubrication over time. The current study focuses on UH-60 Black Hawk viscous damper bearings supporting the tail rotor driveshaft, which were subjected to more than 5800 hours of testing in a heated environment to accelerate the deterioration of the grease. The mechanism of grease degradation is a reduction in the oil/thickener ratio rather than the expected chemical degradation of grease constituents. Over the course of testing, vibration and temperature monitoring of bearings was conducted and trends for failing bearings are presented.

Simultaneous atrazine degradation and E. coli inactivation by simulated solar photo-Fenton-like process using persulfate.

Science.gov (United States)

Garkusheva, Natalya; Matafonova, Galina; Tsenter, Irina; Beck, Sara; Batoev, Valeriy; Linden, Karl

2017-07-29

This work evaluated the feasibility of a photo-Fenton-like process using persulfate (PS) and ferrous iron (Fe 2+ ) under simulated solar radiation for degrading the herbicide atrazine (ATZ, 6-Chloro-N-ethyl-N'-isopropyl-1,3,5-triazine-2,4-diamine) and inactivating E. coli. Milli Q water, lake water, and diluted wastewater effluents were spiked both simultaneously and separately with ATZ (4 mg/L) and E. coli (10 5 CFU/mL), and exposed to treatment. A method for determining the average irradiance throughout the water media in the UV(A+B) range of the Xe lamp emission was developed for bench-scale experiments. These values were used to calculate the UV(A+B) fluences and the solar UV(A+B) energy doses per unit of volume (Q UV(A+B) , kJ/L). The obtained kinetic data were presented versus energy dose. Treatment of lake water at near-neutral pH was ineffective via the photo-Fenton-like process, attaining only 20% ATZ removal and 1-log reduction of E. coli. In Milli Q water and wastewater, the complete degradation of ATZ in the absence of bacteria was observed at an average energy dose of 1.5 kJ/L (60 min), while in the presence of cells the degradation efficiency was ∼60%. When ATZ was present, E. coli inactivation was also affected in Milli Q water, with 1.4-log reduction (93%) at a dose of 1.6 kJ/L (60 min), whereas in wastewater complete inactivation was achieved at a lower dose of 1.3 kJ/L (45 min). The energy requirements on a Q UV(A+B) basis for simultaneous 90% ATZ removal and 99.99% E. coli inactivation in Milli Q water and wastewater were shown to be less than 10 kJ/L. This suggests the solar/PS/Fe 2+ system is promising for simultaneous treatment and disinfection of wastewater effluents.

Atrazine biodegradation modulated by clays and clay/humic acid complexes

International Nuclear Information System (INIS)

Besse-Hoggan, Pascale; Alekseeva, Tatiana; Sancelme, Martine; Delort, Anne-Marie; Forano, Claude

2009-01-01

The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

Development and duration of accelerated degradation of nematicides in different soils

NARCIS (Netherlands)

Smelt, J.H.; Peppel-Groen, van de A.E.; Pas, van der L.J.T.; Dijksterhuis, A.

1996-01-01

The development and duration of accelerated degradation of nematicides were studied in incubation experiments with soils from three experimental fields that had been treated annually for three to ten years with aldicarb, oxamyl, ethoprophos, fenamiphos or 1,3-dichloropropene. Highly accelerated

Degradation of carrageenan by low energy electron accelerator

International Nuclear Information System (INIS)

Relleve, L.; Aranilla, C.; Abad, L.; Dela Rosa, A.; Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio

2004-01-01

Degradation of κ-carrageenan using vessel-type low energy electron accelerator was investigated. Carrageenan with different molecular weights were obtained from irradiation of high molecular weight (HMW) and low molecular weight (LMW) κ-carrageenan. Other results presented were obtained from degradation studies of carrageenan by gamma rays. The decrease in molecular weight was accompanied by partial desulfation. From comparison of radiation degradation yield (Gd), it was found that the susceptibility to radiation of the three types of carrageenans in aqueous/gel forms follows the order of λ->ι->>κ- and could have been influenced by their conformational state. κ-carrageenan with molecular weight of ca. 10,000 showed strong growth promotion effect for potato in tissue culture. (author)

Accelerated degradation of the D2 protein of photosystem II under ultraviolet radiation

International Nuclear Information System (INIS)

Jansen, M.A.K.; Edelman, M.; Greenberg, B.M.; Gaba, V.

1996-01-01

The D2 protein of photosystem II is relatively stable in vivo under photosynthetic active radiation, but its degradation accelerates under UVB radiation. Little is known about accelerated D2 protein degradation. We characterized wavelength dependence and sensitivity toward photosystem II inhibitors. The in vivo D2 degradation spectrum resembles the pattern for the rapidly turning over D1 protein of photosystem II, with rates being maximal in the UVB region. We propose that D2 degradation, like D1 degradation, is activated by distinct photosensitizers in the UVB and visible regions of the spectrum. In both wavelength regions, photosystem II inhibitors that are known to be targeted to the D1 protein affect D2 degradation. This suggests that degradation of the two proteins is coupled, D2 degradation being influenced by events occurring at the Q B niche on the D1 protein. (Author)

Atrazine distribution measured in soil and leachate following infiltration conditions.

Science.gov (United States)

Neurath, Susan K; Sadeghi, Ali M; Shirmohammadi, Adel; Isensee, Allan R; Torrents, Alba

2004-01-01

Atrazine transport through packed 10 cm soil columns representative of the 0-10 cm soil horizon was observed by measuring the atrazine recovery in the total leachate volume, and upper and lower soil layers following infiltration of 7.5 cm water using a mechanical vacuum extractor (MVE). Measured recoveries were analyzed to understand the influence of infiltration rate and delay time on atrazine transport and distribution in the column. Four time periods (0.28, 0.8, 1.8, and 5.5 h) representing very high to moderate infiltration rates (26.8, 9.4, 4.2, and 1.4 cm/h) were used. Replicate soil columns were tested immediately and following a 2-d delay after atrazine application. Results indicate atrazine recovery in leachate was independent of infiltration rate, but significantly lower for infiltration following a 2-d delay. Atrazine distribution in the 0-1 and 9-10 cm soil layers was affected by both infiltration rate and delay. These results are in contrast with previous field and laboratory studies that suggest that atrazine recovery in the leachate increases with increasing infiltration rate. It appears that the difference in atrazine recovery measured using the MVE and other leaching experiments using intact soil cores from this field site and the rain simulation equipment probably illustrates the effect of infiltrating water interacting with the atrazine present on the soil surface. This work suggests that atrazine mobilization from the soil surface is also dependent on interactions of the infiltrating water with the soil surface, in addition to the rate of infiltration through the surface soil.

EFFECTS OF ATRAZINE AND AN ATRAZINE METABOLITE MIXTURE ON DIFFERENTIATED MAMMARY EPITHELIAL CELL MILK PROTEIN PRODUCTION IN CULTURE

Science.gov (United States)

Effects of Atrazine and an Atrazine Metabolite Mixture on Differentiated Mammary Epithelial Cell Milk Protein Production in CultureE.P. Hines, R. Barbee, M. Blanton, M.S. Pooler, and S.E. Fenton. US EPA, ORD/NHEERL, RTD, RTP, NC, 27711, USA.Previous studies have ...

Effects of atrazine on embryos, larvae, and adults of anuran amphibians.

Science.gov (United States)

Allran, J W; Karasov, W H

2001-04-01

We examined the effects of atrazine (0-20 mg/L) on embryos, larvae, and adult anuran amphibian species in the laboratory. Atrazine treatments did not affect hatchability of embryos or 96-h posthatch mortality of larvae of Rana pipiens, Rana sylvatica, or Bufo americanus. Furthermore, atrazine had no effect on swimming speed (measured for R. pipiens only). However, there was a dose-dependent increase in deformed larvae of all three species with increasing atrazine concentration. In adult R. pipiens, atrazine increased buccal and thoracic ventilation, indicating respiratory distress. However, because atrazine had no affect on hemoglobin, this respiratory distress was probably not indicative of reduced oxygen-carrying capacity of the blood. Frogs exposed to the highest atrazine concentration stopped eating immediately after treatment began and did not eat during the 14-d experiment. However, no decreases in mass were measured even for frogs that were not eating, probably because of compensatory fluid gain from edema. Atrazine concentrations found to be deleterious to amphibian embryos and adults are considerably higher than concentrations currently found in surface waters in North America. Therefore, direct toxicity of atrazine is probably not a significant factor in recent amphibian declines.

Hydroponic uptake of atrazine and lambda-cyhalothrin in Juncus effusus and Ludwigia peploides.

Science.gov (United States)

Bouldin, J L; Farris, J L; Moore, M T; Smith, S; Cooper, C M

2006-11-01

Phytoremediation encompasses an array of plant-associated processes known to mitigate contaminants from soil, sediment, and water. Modification of pesticides associated with agricultural runoff includes processes directly associated with aquatic macrophytes in addition to changes in soil geochemistry and associated rhizospheric degradation. Remediation attributes of two vegetative species common to agricultural drainages in the Mississippi Delta, USA, were assessed using atrazine and lambda-cyhalothrin. Concentrations used in 8-d hydroponic exposures were calculated using recommended field applications and a 5% runoff model from a 0.65-cm rainfall event on a 2.02-ha field. While greater atrazine uptake was measured in Juncus effusus, greater lambda-cyhalothrin uptake occurred in Ludwigia peploides. Maximum pesticide uptake was reached within 48h for each exposure and subsequent translocation of pesticides to upper plant biomass occurred in macrophytes exposed to atrazine. Sequestration of 98.2% of lambda-cyhalothrin in roots of L. peploides was measured after 8d. Translocation of lambda-cyhalothrin in J. effusus resulted in 25.4% of pesticide uptake partitioned to upper plant biomass. These individual macrophyte remediation studies measured species- and pesticide-specific uptake rates, indicating that seasonality of pesticide applications and macrophyte emergence might interact strongly to enhance mitigation capabilities in edge-of-field conveyance structures.

Leaching of Br-, metolachlor, alachlor, atrazine, deethylatrazine and deisopropylatrazine in clayey vadoze zone: a field scale experiment in north-east Greece.

Science.gov (United States)

Vryzas, Zisis; Papadakis, Emmanuel Nikolaos; Papadopoulou-Mourkidou, E

2012-04-15

An extensive four-year research program has been carried out to explore and acquire knowledge about the fundamental agricultural practices and processes affecting the mobility and bioavailability of pesticides in soils under semi-arid Mediterranean conditions. Pesticide leaching was studied under field conditions at five different depths using suction cups. Monitoring of metolachlor, alachlor, atrazine, deethylatrazine (DEA), deisopropylatrazine (DIA), and bromide ions in soil water, as well as dye patterns made apparent the significant role of preferential flow to the mobility of the studied compounds. Irrespective to their adsorption capacities and degradation rates, atrazine, metolachlor and bromide ions were simultaneously detected to 160 cm depth. Following 40 mm irrigation, just after their application, both alachlor and atrazine were leached to 160 cm depth within 18 h, giving maximum concentrations of 211 and 199 μg L(-1), respectively. Metolachlor was also detected in all depth when its application was followed by a rainfall event (50 mm) two weeks after its application. The greatest concentrations of atrazine, alachlor and metolachlor in soil water were 1795, 1166 and 845 μg L(-1), respectively. The greatest concentrations of atrazine's degradation products (both DEA and DIA) appeared later in the season compared to the parent compound. Metolachlor exhibited the greatest persistence with concentrations up to 10 μg L(-1) appearing in soil water 18 months after its application. Brilliant blue application followed by 40 mm irrigation clearly depict multi-branching network of preferential flow paths allowing the fast flow of the dye down to 150 cm within 24 h. This network was created by soil cracks caused by shrinking of dry soils, earthworms and plant roots. Chromatographic flow of the stained soil solution was evident only in the upper 10-15 cm of soil. Copyright © 2012 Elsevier Ltd. All rights reserved.

Rice (Oryza sativa) Laccases Involved in Modification and Detoxification of Herbicides Atrazine and Isoproturon Residues in Plants.

Science.gov (United States)

Huang, Meng Tian; Lu, Yi Chen; Zhang, Shuang; Luo, Fang; Yang, Hong

2016-08-24

Atrazine (ATR) and isoproturon (IPU) as herbicides have become serious environmental contaminants due to their overuse in crop production. Although ATR and IPU in soils are easily absorbed by many crops, the mechanisms for their degradation or detoxification in plants are poorly understood. This study identified a group of novel genes encoding laccases (EC 1.10.3.2) that are possibly involved in catabolism or detoxification of ATR and IPU residues in rice. Transcriptome profiling shows at least 22 differentially expressed laccase genes in ATR/IPU-exposed rice. Some of the laccase genes were validated by RT-PCR analysis. The biochemical properties of the laccases were analyzed, and their activities in rice were induced under ATR/IPU exposure. To investigate the roles of laccases in degrading or detoxifying ATR/IPU in rice, transgenic yeast cells (Pichia pastoris X-33) expressing two rice laccase genes (LOC_Os01g63180 and LOC_Os12g15680) were generated. Both transformants were found to accumulate less ATR/IPU compared to the control. The ATR/IPU-degraded products in the transformed yeast cells using UPLC-TOF-MS/MS were further characterized. Two metabolites, hydroxy-dehydrogenated atrazine (HDHA) and 2-OH-isopropyl-IPU, catalyzed by laccases were detected in the eukaryotic cells. These results indicate that the laccase-coding genes identified here could confer degradation or detoxification of the herbicides and suggest that the laccases could be one of the important enzymatic pathways responsible for ATR/IPU degradation/detoxification in rice.

Modelling accelerated degradation data using Wiener diffusion with a time scale transformation.

Science.gov (United States)

Whitmore, G A; Schenkelberg, F

1997-01-01

Engineering degradation tests allow industry to assess the potential life span of long-life products that do not fail readily under accelerated conditions in life tests. A general statistical model is presented here for performance degradation of an item of equipment. The degradation process in the model is taken to be a Wiener diffusion process with a time scale transformation. The model incorporates Arrhenius extrapolation for high stress testing. The lifetime of an item is defined as the time until performance deteriorates to a specified failure threshold. The model can be used to predict the lifetime of an item or the extent of degradation of an item at a specified future time. Inference methods for the model parameters, based on accelerated degradation test data, are presented. The model and inference methods are illustrated with a case application involving self-regulating heating cables. The paper also discusses a number of practical issues encountered in applications.

2004 National Atrazine Occurrence Monitoring Program using the Abraxis ELISA method.

Science.gov (United States)

Graziano, Nicole; McGuire, Michael J; Roberson, Alan; Adams, Craig; Jiang, Hua; Blute, Nicole

2006-02-15

The goal of this project was to gain a better understanding of atrazine occurrence in the United States by surveying drinking water utilities' sources and finished water for atrazine on a weekly basis for seven months. Atrazine is a contaminant of interest because the United States Environmental Protection Agency (USEPA) has found short-term atrazine exposure above the drinking water maximum contaminant level (MCL) to potentially cause heart, lung, and kidney congestion, low blood pressure, muscle spasms, weight loss, and damage to the adrenal glands. Long-term exposure to atrazine concentrations above the drinking water MCL has been linked to weight loss, cardiovascular damage, retinal and muscle degeneration, and cancer. This survey effort improved upon previously conducted atrazine surveys through intensive, high frequency sampling (participating plants sampled their raw and finished water on a weekly basis for approximately seven months). Such an intensive effort allowed the authors to gain a better understanding of short-term atrazine occurrence and its variability in drinking water sources. This information can benefit the drinking water industry by facilitating (1) better atrazine occurrence management (i.e., awareness when plants may be more susceptible to atrazine), (2) more efficient atrazine control (e.g., effective treatment alternatives and more effective response to atrazine occurrence), and (3) treatment cost reduction (e.g., efficient atrazine control can result in substantial cost savings). Forty-seven drinking watertreatment plants located primarily in the Midwestern United States participated in the survey and sampled their raw and finished water on a weekly basis from March through October. Samples were analyzed using the Abraxis enzyme-linked immunosorbent assay (ELISA) test kit. Confirmation samples for quality assurance/quality control (QA/QC) purposes were analyzed using solid-phase extraction (SPE) followed by gas chromatography mass

VUV/UV light inducing accelerated phenol degradation with a low electric input.

Science.gov (United States)

Li, Mengkai; Wen, Dong; Qiang, Zhimin; Kiwi, John

2017-01-23

This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4-6 min. The HO˙ and HO 2 ˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H 2 O 2 and Fe 3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H 2 O 2 or Fe 3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants.

Adsorption-desorption behavior of atrazine on agricultural soils in China.

Science.gov (United States)

Yue, Lin; Ge, ChengJun; Feng, Dan; Yu, Huamei; Deng, Hui; Fu, Bomin

2017-07-01

Adsorption and desorption are important processes that affect atrazine transport, transformation, and bioavailability in soils. In this study, the adsorption-desorption characteristics of atrazine in three soils (laterite, paddy soil and alluvial soil) were evaluated using the batch equilibrium method. The results showed that the kinetics of atrazine in soils was completed in two steps: a "fast" adsorption and a "slow" adsorption and could be well described by pseudo-second-order model. In addition, the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models. It was found that the adsorption data on laterite, and paddy soil were better fitted by the Freundlich model; as for alluvial soil, the Langmuir model described it better. The maximum atrazine sorption capacities ranked as follows: paddy soil>alluvial soil>laterite. Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic. The desorption data showed that negative hysteresis occurred. Furthermore, lower solution pH value was conducive to the adsorption of atrazine in soils. The atrazine adsorption in these three tested soils was controlled by physical adsorption, including partition and surface adsorption. At lower equilibrium concentration, the atrazine adsorption process in soils was dominated by surface adsorption; while with the increase of equilibrium concentration, partition was predominant. Copyright © 2016. Published by Elsevier B.V.

New competitive dendrimer-based and highly selective immunosensor for determination of atrazine in environmental, feed and food samples: the importance of antibody selectivity for discrimination among related triazinic metabolites.

Science.gov (United States)

Giannetto, Marco; Umiltà, Eleonora; Careri, Maria

2014-01-02

A new voltammetric competitive immunosensor selective for atrazine, based on the immobilization of a conjugate atrazine-bovine serum albumine on a nanostructured gold substrate previously functionalized with poliamidoaminic dendrimers, was realized, characterized, and validated in different real samples of environmental and food concern. Response of the sensor was reliable, highly selective and suitable for the detection and quantification of atrazine at trace levels in complex matrices such as territorial waters, corn-cultivated soils, corn-containing poultry and bovine feeds and corn flakes for human use. Selectivity studies were focused on desethylatrazine, the principal metabolite generated by long-term microbiological degradation of atrazine, terbutylazine-2-hydroxy and simazine as potential interferents. The response of the developed immunosensor for atrazine was explored over the 10(-2)-10(3) ng mL(-1) range. Good sensitivity was proved, as limit of detection and limit of quantitation of 1.2 and 5 ng mL(-1), respectively, were estimated for atrazine. RSD values <5% over the entire explored range attested a good precision of the device. Copyright © 2013 Elsevier B.V. All rights reserved.

Degradation of herbicides under different redox conditions in eight Danish aquifers

DEFF Research Database (Denmark)

Pedersen, Philip Grinder; Mosbæk, Hans; Albrechtsen, Hans-Jørgen

2000-01-01

The degradation potential of the herbicides 2,4-D, 2,4,5-T, atrazine, dichlobenil, DNOC, bentazone, DCP (dichloroprop), IPU (isoproturon), MCPA and MCPP (mecoprop) and the degradation product from dichlobenil 2,6-dichlorobenzamide (BAM) were investigated in laboratory incubations with sediment...

Atrazine determination and some of their degradation products in soils and water by means of liquid chromatography of high resolution

International Nuclear Information System (INIS)

Olarte, Israel; Guerrero, Jairo Arturo; Fuentes, Cilia

1999-01-01

This study describes the validation of the analytical method for the simultaneous determination of atrazine (AT) and its metabolites deisopropylatrazine (DIA) and deetylatrazine (DEA) in irrigation water and agricultural soil. Field samples were collected in a cornfield located in Saldana, (Tolima, Colombia) and treated with 2.9 kg. a.i/ha of atrazine. Samples were collected for three months starting after herbicide treatment. The quantitative determination of the compounds of interest was carried out by HPLC with UV detection in a lichrospher RP-18 column of 125 x 4 mm, 5 , using a gradient of acetonitrile-water as mobile phase. The compounds were extracted from the water matrix and concentrated using solid phase extraction (SPE). From the soil matrix the compounds were extracted with methanol followed by a clean up with dichloromethane and buffer phosphate 0.01 M, pH 10.0. Calibration curves were linear over a concentration range of 6 /L- 30 /L in water and 30 /kg - 200 /kg in soil. The method is specific and sensitive with a detection limit of 0.6 /L for DIA, 0.7 /L for DIA and AT in water, 2.0 /kg for DIA, 2.3 /kg for DIA and AT in soil. Recovery experiments were performed with irrigation water samples yielding average recoveries between 80-100% and performed on soil samples yielding average recoveries between 45-65%. DIA and DEA were not detected in neither water nor soil field samples, but atrazine was found in water after the first month following herbicide application at a concentration level of 5,8 /L, and in soil AT a concentration level of 97 /kg - at the second month, no atrazine was found in water but 42 /kg were detected in soil

Optimal design of constant-stress accelerated degradation tests using the M-optimality criterion

International Nuclear Information System (INIS)

Wang, Han; Zhao, Yu; Ma, Xiaobing; Wang, Hongyu

2017-01-01

In this paper, we propose the M-optimality criterion for designing constant-stress accelerated degradation tests (ADTs). The newly proposed criterion concentrates on the degradation mechanism equivalence rather than evaluation precision or prediction accuracy which is usually considered in traditional optimization criteria. Subject to the constraints of total sample number, test termination time as well as the stress region, an optimum constant-stress ADT plan is derived by determining the combination of stress levels and the number of samples allocated to each stress level, when the degradation path comes from inverse Gaussian (IG) process model with covariates and random effects. A numerical example is presented to verify the robustness of our proposed optimum plan and compare its efficiency with other test plans. Results show that, with a slightly relaxed requirement of evaluation precision and prediction accuracy, our proposed optimum plan reduces the dispersion of the estimated acceleration factor between the usage stress level and a higher accelerated stress level, which makes an important contribution to reliability demonstration and assessment tests. - Highlights: • We establish the necessary conditions for degradation mechanism equivalence of ADTs. • We propose the M-optimality criterion for designing constant-stress ADT plans. • The M-optimality plan reduces the dispersion of the estimated accelerated factors. • An electrical connector with its stress relaxation data is used for illustration.

Nuclear-waste-package materials degradation modes and accelerated testing

International Nuclear Information System (INIS)

1981-09-01

This report reviews the materials degradation modes that may affect the long-term behavior of waste packages for the containment of nuclear waste. It recommends an approach to accelerated testing that can lead to the qualification of waste package materials in specific repository environments in times that are short relative to the time period over which the waste package is expected to provide containment. This report is not a testing plan but rather discusses the direction for research that might be considered in developing plans for accelerated testing of waste package materials and waste forms

Influence of smectite hydration and swelling on atrazine sorption behavior.

Science.gov (United States)

Chappell, Mark A; Laird, David A; Thompson, Michael L; Li, Hui; Teppen, Brian J; Aggarwal, Vaneet; Johnston, Cliff T; Boyd, Stephen A

2005-05-01

Smectites, clay minerals commonly found in soils and sediments, vary widely in their ability to adsorb organic chemicals. Recent research has demonstrated the importance of surface charge density and properties of exchangeable cations in controlling the affinity of smectites for organic molecules. In this study, we induced hysteresis in the crystalline swelling of smectites to test the hypothesis that the extent of crystalline swelling (or interlayer hydration status) has a large influence on the ability of smectites to adsorb atrazine from aqueous systems. Air-dried K-saturated Panther Creek (PC) smectite swelled less (d(001) = 1.38 nm) than never-dried K-PC (d(001) = 1.7 nm) when rehydrated in 20 mM KCl. Correspondingly, the air-dried-rehydrated K-PC had an order of magnitude greater affinity for atrazine relative to the never-dried K-PC. Both air-dried-rehydrated and never-dried Ca-PC expanded to approximately 2.0 nm in 10 mM CaCl2 and both samples had similar affinities for atrazine that were slightly lower than that of never-dried K-PC. The importance of interlayer hydration status in controlling sorption affinity was confirmed by molecular modeling, which revealed much greater interaction between interlayer water molecules and atrazine in a three-layer hydrate relative to a one-layer hydrate. The entropy change on moving atrazine from a fully hydrated state in the bulk solution to a partially hydrated state in the smectite interlayers is believed to be a major factor influencing sorption affinity. In an application test, choice of background solution (20 mM KCl versus 10 mM CaCl2) and air-drying treatments significantly affected atrazine sorption affinities for three-smectitic soils; however, the trends were not consistent with those observed for the reference smectite. Further, extending the initial rehydration time from 24 to 240 h (prior to adding atrazine) significantly decreased the soil's sorption affinity for atrazine. We conclude that interlayer

Influence of lead on atrazine uptake by rice (Oryza sativa L.) seedlings from nutrient solution.

Science.gov (United States)

Su, Yu-Hong; Zhu, Yong-Guan

2005-01-01

Atrazine is a widely used herbicide, and its persistence in soil and water causes environmental concerns. In the past, plant uptake processes are mainly investigated for single contaminants. However, in many cases, contaminants co-exist in environmental matrix, such as soil, and plant uptake of one contaminant may be influenced by its co-existing ones. The uptake of atrazine by rice seedlings (Oryza sativa L.) from nutrient solution through the roots was investigated in a solution culture, over an exposure period of 4 weeks. Atrazine accumulation in plant tissues was determined by gas chromatography, and lead was determined using atomic absorption spectrometry. With different ratios of atrazine and Pb2+ concentrations in solution, the observed atrazine concentrations in shoots and roots varied significantly. In atrazine-Pb2+ mixture systems, the added Pb2+ either increased or decreased the concentrations or BCFs of atrazine in seedlings (relative to those without Pb2+), depending on the atrazine-Pb2+ ratio in nutrient solution. The enhanced atrazine uptake results presumably from atrazine-Pb2+ complex formation. The reduced atrazine uptake, which occurred mainly at high atrazine concentrations, is attributed to atrazine toxicity that inhibited seedling growth and transpiration. The formation of atrazine-Pb2+ complex both in the solution and within plant tissues may affect the accumulation of both contaminants by rice plants.

A Bayesian Optimal Design for Sequential Accelerated Degradation Testing

Directory of Open Access Journals (Sweden)

Xiaoyang Li

2017-07-01

Full Text Available When optimizing an accelerated degradation testing (ADT plan, the initial values of unknown model parameters must be pre-specified. However, it is usually difficult to obtain the exact values, since many uncertainties are embedded in these parameters. Bayesian ADT optimal design was presented to address this problem by using prior distributions to capture these uncertainties. Nevertheless, when the difference between a prior distribution and actual situation is large, the existing Bayesian optimal design might cause some over-testing or under-testing issues. For example, the implemented ADT following the optimal ADT plan consumes too much testing resources or few accelerated degradation data are obtained during the ADT. To overcome these obstacles, a Bayesian sequential step-down-stress ADT design is proposed in this article. During the sequential ADT, the test under the highest stress level is firstly conducted based on the initial prior information to quickly generate degradation data. Then, the data collected under higher stress levels are employed to construct the prior distributions for the test design under lower stress levels by using the Bayesian inference. In the process of optimization, the inverse Gaussian (IG process is assumed to describe the degradation paths, and the Bayesian D-optimality is selected as the optimal objective. A case study on an electrical connector’s ADT plan is provided to illustrate the application of the proposed Bayesian sequential ADT design method. Compared with the results from a typical static Bayesian ADT plan, the proposed design could guarantee more stable and precise estimations of different reliability measures.

Response of ligninolytic macrofungi to the herbicide atrazine: dose-response bioassays.

Science.gov (United States)

Cupul, Wilberth Chan; Abarca, Gabriela Heredia; Vázquez, Refugio Rodríguez; Salmones, Dulce; Hernández, Rigoberto Gaitán; Gutiérrez, Enrique Alarcón

2014-01-01

The effect of atrazine concentrations on mycelial growth and ligninolytic enzyme activities of eight native ligninolytic macrofungi isolated in Veracruz, México, were evaluated in a semi-solid culture medium. Inhibition of mycelial growth and growth rates were significantly affected (p=0.05) by atrazine concentrations (468, 937, 1875, and 3750 mg/l). In accordance with the median effective concentration (EC50), Pleurotus sp. strain 1 proved to be the most tolerant isolate to atrazine (EC50=2281.0 mg/l), although its enzyme activity was not the highest. Pycnoporus sanguineus strain 2, Daedalea elegans and Trametes maxima showed high laccase activity (62.7, 31.9, 29.3 U mg/protein, respectively) without atrazine (control); however, this activity significantly increased (p<0.05) (to 191.1, 83.5 and 120.6 U mg/protein, respectively) owing to the effect of atrazine (937 mg/l) in the culture medium. Pleurotus sp. strain 2 and Cymatoderma elegans significantly increased (p<0.05) their manganese peroxidase (MnP) activities under atrazine stress at 468 mg/l. The isolates with high EC50 (Pleurotus sp. strain 1) and high enzymatic activity (P. sanguineus strain 2 and T. maxima) could be considered for future studies on atrazine mycodegradation. Furthermore, this study confirms that atrazine can increase laccase and MnP activities in ligninolytic macrofungi. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España. All rights reserved.

Life prediction of OLED for constant-stress accelerated degradation tests using luminance decaying model

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jianping, E-mail: jpzhanglzu@163.com [College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Li, Wenbin [College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Cheng, Guoliang; Chen, Xiao [Shanghai Tianyi Electric Co., Ltd., Shanghai 201611 (China); Wu, Helen [School of Computing, Engineering and Mathematics, University of Western Sydney, Sydney 2751 (Australia); Herman Shen, M.-H. [Department of Mechanical and Aerospace Engineering, The Ohio State University, OH 43210 (United States)

2014-10-15

In order to acquire the life information of organic light emitting diode (OLED), three groups of constant stress accelerated degradation tests are performed to obtain the luminance decaying data of samples under the condition that the luminance and the current are respectively selected as the indicator of performance degradation and the test stress. Weibull function is applied to describe the relationship between luminance decaying and time, least square method (LSM) is employed to calculate the shape parameter and scale parameter, and the life prediction of OLED is achieved. The numerical results indicate that the accelerated degradation test and the luminance decaying model reveal the luminance decaying law of OLED. The luminance decaying formula fits the test data very well, and the average error of fitting value compared with the test data is small. Furthermore, the accuracy of the OLED life predicted by luminance decaying model is high, which enable rapid estimation of OLED life and provide significant guidelines to help engineers make decisions in design and manufacturing strategy from the aspect of reliability life. - Highlights: • We gain luminance decaying data by accelerated degradation tests on OLED. • The luminance decaying model objectively reveals the decaying law of OLED luminance. • The least square method (LSM) is employed to calculate Weibull parameters. • The plan designed for accelerated degradation tests proves to be feasible. • The accuracy of the OLED life and the luminance decaying fitting formula is high.

Life prediction of OLED for constant-stress accelerated degradation tests using luminance decaying model

International Nuclear Information System (INIS)

Zhang, Jianping; Li, Wenbin; Cheng, Guoliang; Chen, Xiao; Wu, Helen; Herman Shen, M.-H.

2014-01-01

In order to acquire the life information of organic light emitting diode (OLED), three groups of constant stress accelerated degradation tests are performed to obtain the luminance decaying data of samples under the condition that the luminance and the current are respectively selected as the indicator of performance degradation and the test stress. Weibull function is applied to describe the relationship between luminance decaying and time, least square method (LSM) is employed to calculate the shape parameter and scale parameter, and the life prediction of OLED is achieved. The numerical results indicate that the accelerated degradation test and the luminance decaying model reveal the luminance decaying law of OLED. The luminance decaying formula fits the test data very well, and the average error of fitting value compared with the test data is small. Furthermore, the accuracy of the OLED life predicted by luminance decaying model is high, which enable rapid estimation of OLED life and provide significant guidelines to help engineers make decisions in design and manufacturing strategy from the aspect of reliability life. - Highlights: • We gain luminance decaying data by accelerated degradation tests on OLED. • The luminance decaying model objectively reveals the decaying law of OLED luminance. • The least square method (LSM) is employed to calculate Weibull parameters. • The plan designed for accelerated degradation tests proves to be feasible. • The accuracy of the OLED life and the luminance decaying fitting formula is high

Antibody conjugated glycine doped polyaniline nanofilms as efficient biosensor for atrazine

Science.gov (United States)

Bhardwaj, Sanjeev K.; Sharma, Amit L.; Kim, Ki-Hyun; Deep, Akash

2017-12-01

Atrazine is an important member of triazine family of pesticides. The development of its detection methods gained great attention due to the potential health risks associated with its contamination in various media including water, soil, and food. The contamination of atrazine in drinking water beyond the legal permissible limit of EPA (e.g. 3 ng ml-1) may cause various damages to living organisms (e.g. heart, urinary, and limb defects). In this research, we discuss the potential significance of a highly sensitive conductometric immunosensor for sensing the atrazine pesticide. To this end, electrochemical assembly of glycine doped polyaniline (PAni) nanofilms on silicon (Si) substrate was built and modified further with anti-atrazine antibodies. The herein developed immunosensor offered highly sensitive detection of atrazine with a low detection limit of 0.07 ng ml-1. The proposed biosensor was simple in design with excellent performance in terms of its sensitivity, stability and specificity. Highlights •Glycine doped PAni nanofilms have been electropolymerized on Silicon substrates. •Functionality of the above thin films provides opportunity to develop an immunosensing platform. •Highly sensitive and specific detection of atrazine has been realized over a wide concentration range with a LOD of 0.07 ng ml-1. Novelty statement Atrazine is a widely used pesticide in the agriculture sector. It is highly recommended to develop simple biosensing systems for enabling the prospect of routine monitoring. The present research for the first time proposes the design of a glycine doped PAni based simple and highly effective biosensor for the atrazine pesticide. The doping of glycine has easily generated functional groups on the nano-PAni material for further convenient immobilization of anti-atrazine antibodies. The proposed sensor can be highlighted with advantages like ease of fabrication, use of environment friendly functionalization agent, specificity, wide

Atrazine acts as an endocrine disrupter by inhibiting cAMP-specific phosphodiesterase-4

International Nuclear Information System (INIS)

Kucka, Marek; Pogrmic-Majkic, Kristina; Fa, Svetlana; Stojilkovic, Stanko S.; Kovacevic, Radmila

2012-01-01

Atrazine, one of the most commonly used herbicides worldwide, acts as an endocrine disruptor, but the mechanism of its action has not been characterized. In this study, we show that atrazine rapidly increases cAMP levels in cultured rat pituitary and testicular Leydig cells in a concentration-dependent manner, but less effectively than 3-isobutyl-1-methylxanthine, a competitive non-specific inhibitor of phosphodiesterases (PDEs). In forskolin (an activator of adenylyl cyclase)- and probenecid (an inhibitor of cyclic nucleotide transporters)-treated cells, but not in 3-isobutyl-1-methylxanthine-treated cells, atrazine further increased cAMP levels, indicating that inhibition of PDEs accounts for accumulation of cAMP. In contrast to cAMP, atrazine did not alter cGMP levels, further indicating that it inhibits cAMP-specific PDEs. Atrazine-induced changes in cAMP levels were sufficient to stimulate prolactin release in pituitary cells and androgen production in Leydig cells, indicating that it acts as an endocrine disrupter both in cells that secrete by exocytosis of prestored hormones and in cells that secrete by de novo hormone synthesis. Rolipram abolished the stimulatory effect of atrazine on cAMP release in both cell types, suggesting that it acts as an inhibitor of PDE4s, isoforms whose mRNA transcripts dominate in pituitary and Leydig cells together with mRNA for PDE8A. In contrast, immortalized lacto-somatotrophs showed low expression of these mRNA transcripts and several fold higher cAMP levels compared to normal pituitary cells, and atrazine was unable to further increase cAMP levels. These results indicate that atrazine acts as a general endocrine disrupter by inhibiting cAMP-specific PDE4s. -- Highlights: ► Atrazine stimulates cAMP accumulation in pituitary and Leydig cells. ► Atrazine also stimulates PRL and androgens secretion. ► Stimulatory effects of atrazine were abolished in cells with IBMX-inhibited PDEs. ► Atrazine specificity toward c

Effectiveness of narrow grass hedges in reducing atrazine runoff under different slope gradient conditions.

Science.gov (United States)

Wang, Qinghai; Li, Cui; Chen, Chao; Chen, Jie; Zheng, Ruilun; Que, Xiaoe

2018-03-01

Atrazine is frequently detected in surface runoff and poses a potential threat to the environment. Grass hedges may minimize runoff loss of atrazine from crop fields. Therefore, the effectiveness of two grass hedges (Melilotus albus and Pennisetum alopecuroides) in controlling atrazine runoff was investigated using simulated rainfall on lands at different slope gradients (15 and 20%) in northern China. Results showed that a storm (40 mm in 1 h), occurring 4 h after atrazine application, caused a loss of 3% of the applied amount. Atrazine loss under 20% slope was significantly greater than that under 15% slope in control plots. Atrazine exports associated with the water fraction accounted for the majority of total loss. Pennisetum hedges were more efficient in controlling atrazine loss with runoff compared to Melilotus hedges. No significant difference in the capacity of grass hedges to reduce atrazine exports was observed between 15 and 20% slopes. These findings suggest grass hedges are effective in minimizing atrazine runoff in northern China, and Pennisetum hedges should be preferentially used on sloping croplands in similar climatic regions.

In vitro atrazine exposure affects the phenotypic and functional maturation of dendritic cells

International Nuclear Information System (INIS)

Pinchuk, Lesya M.; Lee, Sang-Ryul; Filipov, Nikolay M.

2007-01-01

Recent data suggest that some of the immunotoxic effects of the herbicide atrazine, a very widely used pesticide, may be due to perturbations in dendritic cell (DC) function. As consequences of atrazine exposure on the phenotypic and functional maturation of DC have not been studied, our objective was, using the murine DC line, JAWSII, to determine whether atrazine will interfere with DC maturation. First, we characterized the maturation of JAWSII cells in vitro by inducing them to mature in the presence of growth factors and selected maturational stimuli in vitro. Next, we exposed the DC cell line to a concentration range of atrazine and examined its effects on phenotypic and functional maturation of DC. Atrazine exposure interfered with the phenotypic and functional maturation of DC at non-cytotoxic concentrations. Among the phenotypic changes caused by atrazine exposure was a dose-dependent removal of surface MHC-I with a significant decrease being observed at 1 μM concentration. In addition, atrazine exposure decreased the expression of the costimulatory molecule CD86 and it downregulated the expression of the CD11b and CD11c accessory molecules and the myeloid developmental marker CD14. When, for comparative purposes, we exposed primary thymic DC to atrazine, MHC-I and CD11c expression was also decreased. Phenotypic changes in JAWSII DC maturation were associated with functional inhibition of maturation as, albeit at higher concentrations, receptor-mediated antigen uptake was increased by atrazine. Thus, our data suggest that atrazine directly targets DC maturation and that toxicants such as atrazine that efficiently remove MHC-I molecules from the DC surface are likely to contribute to immune evasion

Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

NARCIS (Netherlands)

Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

2015-01-01

A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

Light-current-induced acceleration of degradation of methylammonium lead iodide perovskite solar cells

Science.gov (United States)

Xiang, Yuren; Zhang, Fan; He, Junjie; Lian, Jiarong; Zeng, Pengju; Song, Jun; Qu, Junle

2018-04-01

The photo-conversion efficiency of perovskite solar cells (PSCs) has been improved considerably in recent years, but the poor stability of PSCs still prevents their commercialization. In this report, we use the rate of the integrated short-circuit current change (Drate) to investigate the performance degradation kinetics and identify the degradation of PSCs that is accelerated by the light current. The value of Drate increases by an order of magnitude from about 0.02 to 0.35 mA cm-2·min-1 after light-IV testing. The accelerated degradation progress is proven to be dominated by the hydration process and the migration of the iodine ions of the light current. The migration of the iodine ions enhances the hydration process through a chain reaction, enabling the formation of fast diffusion channels for both H2O and O2, which induce the rapid decomposition of the perovskite film and increase the density of the trap state. The X-ray photoelectron spectroscopy measurement data also indicate that the super oxygen may be formed due to the PCBM damage caused by the migration iodine ions. An understanding of the degradation acceleration mechanism would provide an insight into the effect of ion migration on the stability of PSCs.

Effect of compost age and composition on the atrazine removal from solution

Science.gov (United States)

Tsui, L.; Roy, W.R.

2007-01-01

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters. ?? 2006 Elsevier B.V. All rights reserved.

Effect of compost age and composition on the atrazine removal from solution.

Science.gov (United States)

Tsui, Lo; Roy, William R

2007-01-02

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters.

Accelerated thermal and radiation-oxidation combined degradation of electric cable insulation materials

International Nuclear Information System (INIS)

Yagi, Toshiaki; Seguchi, Tadao; Yoshida, Kenzo

1986-03-01

For the development of accelerated testing methodology to estimate the life time of electric cable, which is installed in radiation field such as a nuclear reactor containment vessel, radiation and thermal combined degradation of cable insulation and jacketing materials was studied. The materials were two types of formulated polyethylene, ethylene-propylene rubber, Hypalon, and Neoprene. With Co-60 γ-rays the materials were irradiated up to 0.5 MGy under vacuum and in oxygen under pressure, then exposed to thermal aging at elevated temperature in oxygen. The degradation was investigated by the tensile test, gelfraction, and swelling measurements. The thermal degradation rate for each sample increases with increase of oxygen concentration, i.e. oxygen pressure, during the aging, and tends to saturate above 0.2 MPa of oxygen pressure. Then, the effects of irradiation and the temperature on the thermal degradation rate were investigated at the oxygen pressure of 0.2 MPa in the temperature range from 110 deg C to 150 deg C. For all of samples irradiated in oxygen, the following thermal degradation rate was accelerated by several times comparing with unirradiated samples, while the rate of thermal degradation for the sample except Neoprene irradiated under vacuum was nearly equal to that of unirradiated one. By the analysis of thermal degradation rate against temperature using Arrhenius equation, it was found that the activation energy tends to decrease for the samples irradiated in oxidation condition. (author)

Reliability assessment for metallized film pulse capacitors with accelerated degradation test

International Nuclear Information System (INIS)

Zhao Jianyin; Liu Fang; Xi Wenjun; He Shaobo; Wei Xiaofeng

2011-01-01

The high energy density self-healing metallized film pulse capacitor has been applied to all kinds of laser facilities for their power conditioning systems, whose reliability is straightforward affected by the reliability level of capacitors. Reliability analysis of highly reliable devices, such as metallized film capacitors, is a challenge due to cost and time restriction. Accelerated degradation test provides a way to predict its life cost and time effectively. A model and analyses for accelerated degradation data of metallized film capacitors are described. Also described is a method for estimating the distribution of failure time. The estimation values of the unknown parameters in this model are 9.066 9 x 10 -8 and 0.022 1. Both the failure probability density function (PDF) and the cumulative distribution function (CDF) can be presented by this degradation failure model. Based on these estimation values and the PDF/CDF, the reliability model of the metallized film capacitors is obtained. According to the reliability model, the probability of the capacitors surviving to 20 000 shot is 0.972 4. (authors)

Degradation of contrasting pesticides by white rot fungi and its relationship with ligninolytic potential.

Science.gov (United States)

Bending, Gary D; Friloux, Maxime; Walker, Allan

2002-06-18

The capacity of nine species of white rot fungus from a variety of basidiomycete orders to degrade contrasting mono-aromatic pesticides was investigated. There was no relationship between degradation of the dye Poly R-478, a presumptive test for ligninolytic potential, and degradation of the highly available pesticides diuron, metalaxyl, atrazine or terbuthylazine in liquid culture. However, there were significant positive correlations between the rates of degradation of the different pesticides. Greatest degradation of all the pesticides was achieved by Coriolus versicolor, Hypholoma fasciculare and Stereum hirsutum. After 42 days, maximum degradation of diuron, atrazine and terbuthylazine was above 86%, but for metalaxyl less than 44%. When grown in the organic matrix of an on-farm "biobed" pesticide remediation system, relative degradation rates of the highly available pesticides by C. versicolor, H. fasciculare and S. hirsutum showed some differences to those in liquid culture. While H. fasciculare and C. versicolor were able to degrade about a third of the poorly available compound chlorpyrifos in biobed matrix after 42 days, S. hirsutum, which was the most effective degrader of the available pesticides, showed little capacity to degrade the compound.

Potential of macrophytes for removing atrazine from aqueous solution Potencial de macrófitas para remoção de atrazine de solução aquosa

Directory of Open Access Journals (Sweden)

F.P Guimarães

2011-01-01

Full Text Available The potential of three macrophytes, Azolla caroliniana, Salvinia minima, and Lemna gibba was assessed in this study to select plants for use in environmental remediation contaminated with atrazine. Experiments were carried out in a greenhouse over six days in pots containing Hoagland 0.25 strength nutritive solution at the following atrazine concentrations: 0; 0.01; 0.1; 1.0; 10.0 mg L-1. Decrease in biomass accumulation was observed in the three macrophytes, as well as toxic effects evidenced by the symptomatology developed by the plants which caused their deaths. The chlorosis and necrosis allowed to observe in the plants the high sensitivity of the three species to the herbicide. Plants presented low potential for removal of atrazine in solution when exposed to low concentrations of the herbicide. However, at the 10.0 mg L-1 atrazine concentration, L. gibba and A. caroliniana showed potential to remove the herbicide from the solution (0.016 and 0.018 mg atrazine per fresh mass gram, respectively. This fact likely resulted from the processes of atrazine adsorption by the dead material. The percentage of atrazine removed from the solution by the plants decreased when the plants were exposed to high concentrations of the pollutant. Azolla caroliniana, S. minima, and L. gibba were not effective in removing the herbicide from solution. The use of these species to remedy aquatic environments was shown to be limited.Avaliou-se, neste estudo, o potencial de três macrófitas - Azolla caroliniana, Salvinia minima e Lemna gibba - com vistas à seleção de plantas para remediação de ambientes contaminados por atrazine. Foram realizados experimentos em casa de vegetação durante seis dias, em vasos contendo solução nutritiva Hoagland (0,25 de força iônica, nas seguintes concentrações de atrazine: 0; 0,01; 0,1; 1,0; e 10,0 mg L-1. A redução da biomassa acumulada pelas macrófitas foi observada, bem como os efeitos de toxidez evidenciados pela

Accelerated degradation of methyl iodide by agrochemicals.

Science.gov (United States)

Zheng, Wei; Papiernik, Sharon K; Guo, Mingxin; Yates, Scott R

2003-01-29

The fumigant methyl iodide (MeI, iodomethane) is considered a promising alternative to methyl bromide (MeBr) for soil-borne pest control in high-cash-value crops. However, the high vapor pressure of MeI results in emissions of a significant proportion of the applied mass into the ambient air, and this may lead to pollution of the environment. Integrating the application of certain agrochemicals with soil fumigation provides a novel approach to reduce excessive fumigant emissions. This study investigated the potential for several agrochemicals that are commonly used in farming operations, including fertilizers and nitrification inhibitors, to transform MeI in aqueous solution. The pseudo-first-order hydrolysis half-life (t(1/2)) of MeI was approximately 108 d, while the transformation of MeI in aqueous solutions containing selected agrochemicals was more rapid, with t(1/2) agrochemicals on the rate of MeI degradation in soil was also determined. Adsorption to soil apparently reduced the availability of some nitrification inhibitors in the soil aqueous phase and lowered the degradation rate in soil. In contrast, addition of the nitrification inhibitors thiourea and allylthiourea to soil significantly accelerated the degradation of MeI, possibly due to soil surface catalysis. The t(1/2) of MeI was 300 h).

Bacteria encapsulated in layered double hydroxides: towards an efficient bionanohybrid for pollutant degradation.

Science.gov (United States)

Halma, Matilte; Mousty, Christine; Forano, Claude; Sancelme, Martine; Besse-Hoggan, Pascale; Prevot, Vanessa

2015-02-01

A soft chemical process was successfully used to immobilize Pseudomonas sp. strain ADP (ADP), a well-known atrazine (herbicide) degrading bacterium, within a Mg2Al-layered double hydroxide host matrix. This approach is based on a simple, quick and ecofriendly direct coprecipitation of metal salts in the presence of a colloidal suspension of bacteria in water. It must be stressed that by this process the mass ratio between inorganic and biological components was easily tuned ranging from 2 to 40. This ratio strongly influenced the biological activity of the bacteria towards atrazine degradation. The better results were obtained for ratios of 10 or lower, leading to an enhanced atrazine degradation rate and percentage compared to free cells. Moreover the biohybrid material maintained this biodegradative activity after four cycles of reutilization and 3 weeks storage at 4°C. The ADP@MgAl-LDH bionanohybrid materials were completely characterized by X-ray diffraction (XRD), FTIR spectroscopy, thermogravimetric analysis and scanning and transmission electronic microscopy (SEM and TEM) evidencing the successful immobilization of ADP within the inorganic matrix. This synthetic approach could be readily extended to other microbial whole-cell immobilization of interest for new developments in biotechnological systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Vertical variation of atrazine mineralization capacity in soils Variación vertical de la capacidad de mineralización de atrazina en suelos

Directory of Open Access Journals (Sweden)

S. Hang

2007-12-01

Full Text Available The variation of atrazine mineralization capacity was investigated in two soil profiles selected with (adapted soil and without (non-adapted soil atrazine application history in Córdoba, Argentina. Atrazine evolution was characterized by balance of 14C-U-ring atrazine radioactivity between mineralized, extractable and non-extractable fractions by means of incubations under laboratory conditions in two soil situations: with dry heat treatment (T105 and without heat treatment (Control. The strong decrease of atrazine mineralization after microbial inactivation during all the incubation period in adapted soil suggests that the atrazine degraders were distributed throughout the entire adapted soil profile and were responsible for atrazine mineralization in subsurface horizons. In the non-adapted soil profile, the cometabolic process of mineralizing atrazine was corroborated. The atrazine mineralization capacity of subsurface horizons, where herbicide accumulation increases, should be considered and stimulated as a mechanism for the natural bioremediation of soils with frequent atrazine application.Se estudió la variación de la capacidad de mineralización de atrazina en dos suelos de la provincia de Córdoba, Argentina. Se seleccionaron dos perfiles de suelos con (suelo adaptado y sin (suelo no adaptado historia de aplicación de atrazina. La evolución de atrazina fue caracterizada mediante el balance de la radioactividad del 14C del anillo triazínico identificando las fracciones mineralizada, extractable y no extractable, durante incubaciones en condiciones de laboratorio con suelo tratado con calor (T105 y sin él (Control. La disminución de la capacidad de degradación de atrazina después de la inactivación microbiana y la limitada recuperación de esa capacidad observada en el perfil de suelo adaptado sugirió que los microorganismos degradadores de atrazina estarían distribuidos en todo el perfil siendo los responsables de la

Treatment of atrazine in nursery irrigation runoff by a constructed wetland.

Science.gov (United States)

Runes, Heather B; Jenkins, Jeffrey J; Moore, James A; Bottomley, Peter J; Wilson, Bruce D

2003-02-01

To investigate the treatment capability of a surface flow wetland at a container nursery near Portland, Oregon, atrazine was introduced during simulated runoff events. Treatment efficiency was evaluated as the percent atrazine recovered (as percent of applied) in the water column at the wetland's outlet. Atrazine treatment efficiency at the outlet of the constructed wetland during a 7-d period ranged from 18-24% in 1998 (experiments 1-3) and 16-17% in 1999 (experiments 4 and 5). Changes in total flow, or frequency and intensity of runoff events did not affect treatment. For experiment 6 in 1999, where the amount, frequency, and duration of runoff events exceeded all other experiments, treatment was compromised. For all experiments, deethylatrazine (DEA) and deisopropylatrazine (DIA) accounted for 13-21% of the initial application. Hydroxyatrazine (HA) was rarely detected in the water. Organic carbon adsorption coefficients (Koc) were determined from batch equilibrium sorption isotherms with wetland sediment, and they decreased in the order of HA > DIA > atrazine > DEA. Static water-sediment column experiments indicated that sorption is an important mechanism for atrazine loss from water passing through the constructed wetland. The results of the MPN assay indicated the existence in the wetland of a low-density population of microorganisms with the potential to mineralize atrazine's ethyl side chain.

Transport of atrazine and dicamba through silt and loam soils

Science.gov (United States)

Tindall, James A.; Friedel, Michael J.

2016-01-01

The objectives of this research were to determine the role of preferential flow paths in the transport of atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) and dicamba (3-6-dichloro-2-methoxybenzoic acid) through silt and loam soils overlying the High Plains aquifer in Nebraska. In a previous study, 3 of 6 study areas demonstrated high percentages of macropores; those three areas were used in this study for analysis of chemical transport. As a subsequent part of the study, 12 intact soil cores (30-cm diameter by 40-cm height), were excavated sequentially, two from each of the following depths: 0-40cm and 40-80cm. These cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties. Two undisturbed experimental field plots, each with a 3-m2 surface area, were installed in three study areas in Nebraska. Each was instrumented with suction lysimeters and tensiometers at depths of 10cm to 80cm in 10-cm increments. Additionally, each plot was planted with corn (Zea mays). A neutron probe access tube was installed in each plot to determine soil w ater content at 15-cm intervals. All plots were enclosed w ith a raised frame (of 8-cm height) to prevent surface runoff. All suction lysimeters were purged monthly for three months and were sampled immediately prior to pre-plant herbicide application to obtain background chemical concentrations. Atrazine and dicamba moved rapidly through the soil, but only after a heavy rainfall event, probably owing to the presence of preferential flow paths and lack of microbial degradation in these soil areas. Staining of laboratory cores showed a positive correlation between the percent area stained by depth and the subsequent breakthrough of Br- in the laboratory and leaching of field-applied herbicides owing to large rainfall events. Suction lysimeter samples in the field showed increases in concentrations of herbicides at depths where laboratory data indicated greater

Atrazine in a corn cultivated area and its relation with the landscape position

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Regimeire Freitas Aquino

2013-10-01

Full Text Available Atrazine is still being used in no-till corn production in Brazil. This herbicide can be moved by overland flow and leached in the soil profile. In both ways, it can pollute water, either by reaching the groundwater or lakes and streams close to the crop field. This study evaluated the presence of atrazine in a dystrophic Yellow-Red Argisol and a dystrophic Melanic Gleisol in a corn field, where atrazine has been applied for 11 years. Overland flow was the main process of atrazine transport on hillslope and leaching was the most important process in the floodplain. Frequency and location of atrazine application in the landscape define this herbicide contamination process.

FATE OF ATRAZINE IN THE AGRICULTURAL SOIL OF CORN FIELDS IN FARS PROVINCE OF IRAN

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S. Nasseri ، M. Dehghani ، S. Amin ، K. Naddafi ، Z. Zamanian

2009-10-01

Full Text Available Atrazine, a herbicide widely used in corn production, is frequently detected as pesticide in water resources. In this research, four agricultural fields with a long history of atrazine application in Shiraz and its vicinity in Fars province of Iran, have been studied to determine the fate of atrazine through the passage of time. These four farms were cultivated under a crop rotation (corn-wheat during the past 10 years. Samples were collected from four soil profiles of 0-10, 10-20, 20-40, and 40-60 cm soil depth at different times. The time intervals for soil sampling started before atrazine application and continued until no atrazine was detected. According to the general linear model, there was no significant difference between atrazine residual concentrations and the soil moisture and depth (p≥0.05. But, significant difference between atrazine residual concentrations and the sampling regions was observed (p<0.001. Based on the data, atrazine leaching and dissipation rate in different soil profiles in the four sampling regions were high and significant. Therefore, there is a high risk of atrazine pollution in groundwater resources of the region.

Insulin receptor degradation is accelerated in cultured lymphocytes from patients with genetic syndromes of extreme insulin resistance

International Nuclear Information System (INIS)

McElduff, A.; Hedo, J.A.; Taylor, S.I.; Roth, J.; Gorden, P.

1984-01-01

The insulin receptor degradation rate was examined in B lymphocytes that were obtained from peripheral blood of normal subjects and patients with several syndromes of extreme insulin resistance. The insulin receptors were surface labeled using Na 125 I/lactoperoxidase and the cells were returned to incubate in growth media. After varying periods of incubation, aliquots of cells were solubilized and the cell content of labeled receptor subunits were measured by immunoprecipitation with anti-receptor antibodies and NaDodSO4/polyacrylamide gel electrophoresis. In cell lines from four patients in whom the number of insulin receptors was reduced by greater than 90%, the rate of receptor loss was greater than normal (t1/2 equals 3.8 +/- 0.9 h vs. 6.5 +/- 1.2 h; mean +/- SD, P less than 0.01). However, a similar acceleration in receptor degradation was seen in cells from five patients with extreme insulin resistance but low-normal insulin receptor concentration (t1/2 equals 4.4 +/- 0.9 h). Thus, all the patients with genetic syndromes of insulin resistance had accelerated receptor degradation, regardless of their receptor concentration. By contrast, insulin receptors on cultured lymphocytes that were obtained from patients with extreme insulin resistance secondary to autoantibodies to the insulin receptor had normal receptor degradation (t1/2 equals 6.1 +/- 1.9 h). We conclude that (a) accelerated insulin receptor degradation is an additional feature of cells from patients with genetic forms of insulin resistance; (b) that accelerated insulin receptor degradation may explain the low-normal receptor concentrations that were seen in some patients with extreme insulin resistance; and (c) that accelerated degradation does not explain the decreased receptor concentration in patients with very low insulin receptor binding and, therefore, by inference, a defect in receptor synthesis must be present in this subgroup

Evaluation of the side effects of poly(epsilon-caprolactone) nanocapsules containing atrazine towards maize plants

Science.gov (United States)

Oliveira, Halley; Stolf-Moreira, Renata; Martinez, Cláudia; Sousa, Gustavo; Grillo, Renato; de Jesus, Marcelo; Fraceto, Leonardo

2015-10-01

Poly(epsilon-caprolactone) (PCL) nanocapsules have been used as a carrier system for the herbicide atrazine, which is commonly applied to maize. We demonstrated previously that these atrazine containing polymeric nanocapsules were ten-fold more effective in the control of mustard plants (a target species), as compared to a commercial atrazine formulation. Since atrazine can have adverse effects on non-target crops, here we analyzed the effect of encapsulated atrazine on growth, physiological and oxidative stress parameters of soil-grown maize plants (Zea mays L.). One day after the post-emergence treatment with PCL nanocapsules containing atrazine (1 mg mL-1), maize plants presented 15 and 21 % decreases in maximum quantum yield of photosystem II and in net CO2 assimilation rate, respectively, as compared to water-sprayed plants. The same treatment led to a 1.8-fold increase in leaf lipid peroxidation in comparison with control plants. However, all of these parameters were unaffected four and eight days after the application of encapsulated atrazine. These results suggested that the negative effects of atrazine were transient, probably due to the ability of maize plants to detoxify the herbicide. When encapsulated atrazine was applied at a ten-fold lower concentration (0.1 mg mL-1), a dosage that is still effective for weed control, no effects were detected even shortly after application. Regardless of the herbicide concentration, neither pre- nor post-emergence treatment with the PCL nanocapsules carrying atrazine resulted in the development of any macroscopic symptoms in maize leaves, and there were no impacts on shoot growth. Additionally, no effects were observed when plants were sprayed with PCL nanocapsules without atrazine. Overall, these results suggested that the use of PCL nanocapsules containing atrazine did not lead to persistent side effects in maize plants, and that the technique could offer a safe tool for weed control without affecting crop growth.

Fate of the herbicide 14C-atrazine during sewage treatment on a lab-scale bioreactor

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Jaime L. M. Oliveira

2013-08-01

Full Text Available Atrazine (2-chloro-4-(ethylamino-6-(isopropylamino-s-triazine is a persistent herbicide used on some crops and it has been found both in ground and surface water and drainage systems. This work studied the behaviour of atrazine during a sewage treatment process by activated sludge. The process was conducted on a laboratory scale using an under fed-batch system with a hydraulic retention time of 24 hours. After this period, the raw sewage (with atrazine was changed and another batch was begun (the sludge age was 7 days old. Radiolabel molecules (14C-atrazine were used for to trace their fate and to measure to the 14C-CO2 and the residues of atrazine were analysed by HPLC/UV. Initially about 50% of radioactivity was sorbed by the settled sludge but it was desorbed with successive additions of raw sewage without atrazine. The final balance of radioactivity showed that 98% of the atrazine was released into the treated effluent, probably without any biodegradation. Therefore, other organic micropollutants with similar characteristics to atrazine may behave a similar way.

Dimethoate and atrazine retention from aqueous solution by nanofiltration membranes.

Science.gov (United States)

Ahmad, A L; Tan, L S; Shukor, S R Abd

2008-02-28

In order to produce sufficient food supply for the ever-increasing human population, pesticides usage is indispensable in the agriculture sector to control crop losses. However, the effect of pesticides on the environment is very complex as undesirable transfers occur continually among different environmental sections. This eventually leads to contamination of drinking water source especially for rivers located near active agriculture practices. This paper studied the application of nanofiltration membrane in the removal of dimethoate and atrazine in aqueous solution. Dimethoate was selected as the subject of study since it is being listed as one of the pesticides in guidelines for drinking water by World Health Organization. Nevertheless, data on effectiveness of dimethoate rejection using membranes has not been found so far. Meanwhile, atrazine is classified as one of the most commonly used pesticides in Malaysia. Separation was done using a small batch-type membrane separation cell with integrated magnetic stirrer while concentration of dimethoate and atrazine in aqueous solution was analyzed using high performance liquid chromatography (HPLC). Four nanofiltration membranes NF90, NF200, NF270 and DK were tested for their respective performance to separate dimethoate and atrazine. Of all four membranes, NF90 showed the best performance in retention of dimethoate and atrazine in water.

The impact of atrazine on several biochemical properties of chernozem soil

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LJ. RADIVOJEVIC

2008-10-01

Full Text Available The impact of the pesticide atrazine on biochemical processes in soil was investigated. Atrazine loadings of 8.0, 40.0 and 80.0 mg/kg soil were laboratory tested in an experiment set up on a clay loam soil. Dehydrogenase activity, change in biomass carbon, soil respiration and metabolic coefficient were examined. The samples were collected for analysis 1, 7, 14, 21, 30 and 60 days after atrazine application. The acquired data indicated that the effect of atrazine on the biochemical activity of the soil depended on its application rate and duration of activity, and the effect was either stimulating or inhibiting. However, the detected changes were found to be transient, indicating that there is no real risk of the compound disrupting the balance of biochemical processes in soil.

Response to variable light intensity in photoacclimated algae and cyanobacteria exposed to atrazine

Energy Technology Data Exchange (ETDEWEB)

Deblois, Charles P.; Dufresne, Karine [Department of Biological Sciences-TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Universite du Quebec a Montreal, Succ. Centre-Ville, Montreal, Quebec (Canada); Juneau, Philippe, E-mail: juneau.philippe@uqam.ca [Department of Biological Sciences-TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Universite du Quebec a Montreal, Succ. Centre-Ville, Montreal, Quebec (Canada)

2013-01-15

Atrazine is frequently detected in freshwater ecosystems exposed to agricultural waste waters and runoffs worldwide and it can affect non-target organisms (mainly photoautotrophic) and modify community structure. Meanwhile, light environment is known to vary between aquatic ecosystems, but also before and during the exposure to atrazine and these variations may modify the sensitivity to atrazine of photoautotroph organisms. In this study, 10 species of phytoplankton (chlorophytes, baccilariophytes and cyanophytes) acclimated to low or high light intensities were exposed to atrazine and light of different intensities to compare their combined effect. Our data showed that chlorophytes and baccilariophytes were more resistant to atrazine compared to cyanophytes for all light conditions. Atrazine was found to inhibit {Phi}{sup Prime }{sub M}, {Psi}{sub 0}, P{sub M} and non-photochemical quenching for all species indicating an effect on electron transport, primary production and photoregulation processes. These data also indicate a higher sensitivity of {Psi}{sub 0} (average {Psi}{sub 0}-EC{sub 50} of 91 {+-} 11 nM or 19.6 {+-} 0.9 {mu}g L{sup -1}) compared to {Phi}{sup Prime }{sub M} (average {Phi}{sup Prime }{sub M}-EC{sub 50} of 217 {+-} 19 nM or 46.8 {+-} 4.1 {mu}g L{sup -1}) and suggest that photoregulation processes activated in presence of light decrease the effect of atrazine. We also showed that increasing light intensity decreased {Phi}{sup Prime }{sub M}-EC{sub 50} in both low (except baccilariophytes) and high light acclimated conditions. Despite this similarity, most species acclimated to high light were found to have higher or similar {Phi}{sup Prime }{sub M}-EC{sub 50} compared to low light acclimated cells and thus, were less sensitive to atrazine in low light and high light environments. We concluded that an increase in the plastoquinone pool induced by acclimation to high light decreased the sensitivity to atrazine in phytoplankton and we hypothesized

Potencial alelopático de 2-benzoxazolinona (boa e sua interação com atrazine no crescimento de plantas Allelopathic potential of 2-benzoxazolinone (boa and its interactions with atrazine on lant growth

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Itamar F. Souza

1994-01-01

Full Text Available Dois experimentos de laboratório foram conduzidos na Universidade de South Dakota, Vemillion, SD, EUA, em 1990, para determinar os efeitos do ácido hidroxâmico benzoxazolinona (BOA, do herbicida atrazine e de suas misturas sobre o crescimento e teor de clorofila de lentilha dágua (Lemna minor. BOA na concentração de 0,5 mM foi aplicado em combinação com atrazine a 0,001 e 0,005 mM em caixas plásticas com 24 células de 2,5 ml, contendo 3 frondes de lentilha dágua em solução nutritiva. BOA e atrazine, aplicados isoladamente, inibiram o número, o peso sêco e o teor de clorofila. Atrazine apresentou uma maior ação inibitória que BOA. A combinação BOA (0,05 mM e atrazine à 0,001 mM foi antagonística. A inibição induzida pelo atrazine a 0,001 mM foi, em parte, neutralizada, porém, com a dose 0,005 mM a sua ação inibitória não foi alterada.Two laboratoy experiments were carried out at the University of South Dakota, Vermillion, SD, USA, in 1990, to determine the effects of hydroxamic acid benzoxazolinone (BOA, the herbicide atrazine, and a mixture there of on duckweed growth and its chlorophyll content. BOA at 0.5 mM concentration was applied in combination with atrazine at 0.001 and 0.005 mM in a 2.5 ml cell tissue cluster dish containing three fronds of duckweed in nutrient solution. Single applications of BOA and atrazine inhibited duckweed frond number, frond dry weight, and its chlorophyll content. Atrazine showed stronger inbibition effect than BOA. The combination BOA and atrazine at 0.001 mM was antagonistic where the inhibition induced by the herbicide was counteracted. Unlike atrazine at 0.00I mM, BOA added to atrazine at 0,005 mM did not counteract the inhibitio caused by the herbicide.

Atrazine is not readily mineralised in 24 temperate soils regardless of pre-exposure to triazine herbicides

International Nuclear Information System (INIS)

Glaesner, Nadia; Baelum, Jacob; Strobel, Bjarne W.; Jacobsen, Carsten S.

2010-01-01

Mineralisation of atrazine in soil has been shown to depend on previous exposure of the herbicide. In this study, 24 Danish soils were collected and screened for potential to mineralise atrazine. Six soils were chosen, because they had never been exposed to atrazine, whereas 18 soils were chosen because of their history of application of atrazine or the related compound terbuthylazine. None of the 24 soils revealed a mineralisation potential of more than 4% of the added atrazine within a 60 day timeframe. In an atrazine adapted French soil, we found 60% mineralisation of atrazine in 30 days. Cattle manure was applied in order to boost the microbial activity, and a 2-3% increase in the atrazine mineralisation was found in some of the temperate soils, while in the highly adapted French soil it caused a 5% reduction. - The study highlights that pre-exposure of soils to triazine herbicides do not result in rapid mineralization in temperate soils.

Demasculinization and feminization of male gonads by atrazine: Consistent effects across vertebrate classes

Science.gov (United States)

Hayes, Tyrone B.; Anderson, Lloyd L.; Beasley, Val R.; de Solla, Shane R.; Iguchi, Taisen; Ingraham, Holly; Kestemont, Patrick; Kniewald, Jasna; Kniewald, Zlatko; Langlois, Valerie S.; Luque, Enrique H.; McCoy, Krista A.; Muñoz-de-Toro, Mónica; Oka, Tomohiro; Oliveira, Cleida A.; Orton, Frances; Ruby, Sylvia; Suzawa, Miyuki; Tavera-Mendoza, Luz E.; Trudeau, Vance L.; Victor-Costa, Anna Bolivar; Willingham, Emily

2015-01-01

Atrazine is the most commonly detected pesticide contaminant of ground water, surface water, and precipitation. Atrazine is also an endocrine disruptor that, among other effects, alters male reproductive tissues when animals are exposed during development. Here, we apply the nine so-called “Hill criteria” (Strength, Consistency, Specificity, Temporality, Biological Gradient, Plausibility, Coherence, Experiment, and Analogy) for establishing cause–effect relationships to examine the evidence for atrazine as an endocrine disruptor that demasculinizes and feminizes the gonads of male vertebrates. We present experimental evidence that the effects of atrazine on male development are consistent across all vertebrate classes examined and we present a state of the art summary of the mechanisms by which atrazine acts as an endocrine disruptor to produce these effects. Atrazine demasculinizes male gonads producing testicular lesions associated with reduced germ cell numbers in teleost fish, amphibians, reptiles, and mammals, and induces partial and/or complete feminization in fish, amphibians, and reptiles. These effects are strong (statistically significant), consistent across vertebrate classes, and specific. Reductions in androgen levels and the induction of estrogen synthesis – demonstrated in fish, amphibians, reptiles, and mammals – represent plausible and coherent mechanisms that explain these effects. Biological gradients are observed in several of the cited studies, although threshold doses and patterns vary among species. Given that the effects on the male gonads described in all of these experimental studies occurred only after atrazine exposure, temporality is also met here. Thus the case for atrazine as an endocrine disruptor that demasculinizes and feminizes male vertebrates meets all nine of the “Hill criteria”. PMID:21419222

Atrazine Contamination in Groundwater at Ejura in the Ashanti Region of Ghana

International Nuclear Information System (INIS)

Quaye, F.A.

2012-01-01

The present study the levels Atrazine, deethylatrazine(DEA) and deisopropylatrazine(DIA) in groundwater at Ejura within the Ejura-Sekyedumase District in the Ashanti region of Ghana which is a major maize growing area in the country. A total of twenty five (25) groundwater samples were collected from six(6) sampling sites within the sampling area and were analyzed using a Varian ProstaHPLC system (410) + autosampler, photodiote array (PDA) detector, UV and fluorescence detectors. The mean concentration of atrazine in the groundwater at Ejura is 0.255 μ/L. The maximum concentration of atrazine was 1.530μ/L and a minimum concentration of 0.20μ/L. The maximum and minimum concentrations for deethylatrazine (DEA) and deisopropylatrazine (DIA) are 0.423μ/L and 0.101μ/L and 0.204μ/L and 0.102μL respectively. The Deethylatrazine to Atrazine Ratio (DAR) was calculated; the values were much less than one suggesting a discrete source of contamination. This gives an indication of the pathway of atrazine contamination as being preferential flow. The levels of Atrazine deethylatrazine (DEA) and deisopropylatrazine (DIA) from the samples analyzed were all below WHO's maximum contamination levels (MCL), 2μ/L. (author)

Plastic antibody based surface plasmon resonance nanosensors for selective atrazine detection

Energy Technology Data Exchange (ETDEWEB)

Yılmaz, Erkut [Department of Chemistry, Aksaray University, 68100 Aksaray (Turkey); Özgür, Erdoğan; Bereli, Nilay; Türkmen, Deniz [Department of Chemistry, Hacettepe University, 06800 Ankara (Turkey); Denizli, Adil, E-mail: denizli@hacettepe.edu.tr [Department of Chemistry, Hacettepe University, 06800 Ankara (Turkey)

2017-04-01

This study reports a surface plasmon resonance (SPR) based affinity sensor system with the use of molecular imprinted nanoparticles (plastic antibodies) to enhance the pesticide detection. Molecular imprinting based affinity sensor is prepared by the attachment of atrazine (chosen as model pesticide) imprinted nanoparticles onto the gold surface of SPR chip. Recognition element of the affinity sensor is polymerizable form of aspartic acid. The imprinted nanoparticles were characterized via FTIR and zeta-sizer measurements. SPR sensors are characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR) and contact angle measurements. The imprinted nanoparticles showed more sensitivity to atrazine than the non-imprinted ones. Different concentrations of atrazine solutions are applied to SPR system to determine the adsorption kinetics. Langmuir adsorption model is found as the most suitable model for this affinity nanosensor system. In order to show the selectivity of the atrazine-imprinted nanoparticles, competitive adsorption of atrazine, simazine and amitrole is investigated. The results showed that the imprinted nanosensor has high selectivity and sensitivity for atrazine. - Highlights: • SPR based affinity sensor system was developed via molecular imprinting. • Recognition element of the affinity sensor is polymerizable form of an amino acid. • Combination of SPR and MIP offers highly selective sensor with long shelf-life. • Plastic antibody based biomimetic sensors offer relatively cheaper production. • Plastic antibody based biomimetic sensors offer high physical, chemical stability.

Plastic antibody based surface plasmon resonance nanosensors for selective atrazine detection

International Nuclear Information System (INIS)

Yılmaz, Erkut; Özgür, Erdoğan; Bereli, Nilay; Türkmen, Deniz; Denizli, Adil

2017-01-01

This study reports a surface plasmon resonance (SPR) based affinity sensor system with the use of molecular imprinted nanoparticles (plastic antibodies) to enhance the pesticide detection. Molecular imprinting based affinity sensor is prepared by the attachment of atrazine (chosen as model pesticide) imprinted nanoparticles onto the gold surface of SPR chip. Recognition element of the affinity sensor is polymerizable form of aspartic acid. The imprinted nanoparticles were characterized via FTIR and zeta-sizer measurements. SPR sensors are characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR) and contact angle measurements. The imprinted nanoparticles showed more sensitivity to atrazine than the non-imprinted ones. Different concentrations of atrazine solutions are applied to SPR system to determine the adsorption kinetics. Langmuir adsorption model is found as the most suitable model for this affinity nanosensor system. In order to show the selectivity of the atrazine-imprinted nanoparticles, competitive adsorption of atrazine, simazine and amitrole is investigated. The results showed that the imprinted nanosensor has high selectivity and sensitivity for atrazine. - Highlights: • SPR based affinity sensor system was developed via molecular imprinting. • Recognition element of the affinity sensor is polymerizable form of an amino acid. • Combination of SPR and MIP offers highly selective sensor with long shelf-life. • Plastic antibody based biomimetic sensors offer relatively cheaper production. • Plastic antibody based biomimetic sensors offer high physical, chemical stability.

Lichen microalgae are sensitive to environmental concentrations of atrazine.

Science.gov (United States)

Traba, Helena Moreno; Domínguez-Morueco, Noelia; Barreno, Eva; Catalá, Myriam

2017-04-03

The identification of new organisms for environmental toxicology bioassays is currently a priority, since these tools are strongly limited by the ecological relevance of taxa used to study global change. Lichens are sensitive bioindicators of air quality and their microalgae are an untapped source for new low-cost miniaturized bioassays with ecological importance. In order to increase the availability of a wider range of taxa for bioassays, the sensitivity of two symbiotic lichen microalgae, Asterochloris erici and Trebouxia sp. TR9, to atrazine was evaluated. To achieve this goal, axenic cultures of these phycobionts in suspension were exposed to a range of environmental concentrations of the herbicide atrazine, a common water pollutant. Optical density and chlorophyll autofluorescence were used as endpoints of ecotoxicity and ecophysiology on cell suspensions. Results show that lichen microalgae show high sensitivity to very low doses of atrazine, being higher in Asterochloris erici than in Trebouxia sp. TR9. We conclude that environmental concentrations of atrazine could modify population dynamics probably through a shift in reproduction strategies of these organisms. This seminal work is a breakthrough in the use of lichen microalgae in the assessment of micropollution effects on biodiversity.

Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes

OpenAIRE

Chirnside, Anastasia E. M.; Ritter, William F.; Radosevich, Mark

2011-01-01

Soils from bulk pesticide mixing and loading (mix-load) sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT) and alachlor (2-chloro- 2  , 6  -...

Accelerated degradation by UV radiation of adhesive materials used in solar equipment

International Nuclear Information System (INIS)

Tilca, F.; Acosta, D; Barcena, H.; Suarez, H.; Cadena, C.; Bolzi, Claudio

2003-01-01

Several materials which are used as common adhesives in photovoltaic cells, were tested in order to study their stability. Accelerated degradation effects were produced using high radiation doses of UV-C and UV-b in a previously described camera at different times. The exposed and unexposed films were studied by transmittance, X-ray diffraction and infrared. The results are in agreement with complex degradation process at long exposition times, while transmittance doesn't change significantly. (author)

Response of reservoir atrazine concentrations following regulatory and management changes

Science.gov (United States)

Since the early 1990s, atrazine concentrations in United States drinking water supplies exceeding the drinking water standard of 3 parts per billion (ppb) have been identified as a costly and major water quality concern. Atrazine levels in Columbus, Ohio tap water reached 8.74 ppb in the early 1990s...

Evaluation of the side effects of poly(epsilon-caprolactone nanocapsules containing atrazine towards maize plants

Directory of Open Access Journals (Sweden)

Halley Caixeta Oliveira

2015-10-01

Full Text Available Poly(epsilon-caprolactone (PCL nanocapsules have been used as a carrier system for the herbicide atrazine, which is commonly applied to maize. We demonstrated previously that these atrazine containing polymeric nanocapsules were ten-fold more effective in the control of mustard plants (a target species, as compared to a commercial atrazine formulation. Since atrazine can have adverse effects on non-target crops, here we analyzed the effect of encapsulated atrazine on growth, physiological and oxidative stress parameters of soil-grown maize plants (Zea mays L.. One day after the post-emergence treatment with PCL nanocapsules containing atrazine (1 mg mL-1, maize plants presented 15 and 21 % decreases in maximum quantum yield of photosystem II and in net CO2 assimilation rate, respectively, as compared to water-sprayed plants. The same treatment led to a 1.8-fold increase in leaf lipid peroxidation in comparison with control plants. However, all of these parameters were unaffected four and eight days after the application of encapsulated atrazine. These results suggested that the negative effects of atrazine were transient, probably due to the ability of maize plants to detoxify the herbicide. When encapsulated atrazine was applied at a ten-fold lower concentration (0.1 mg mL-1, a dosage that is still effective for weed control, no effects were detected even shortly after application. Regardless of the herbicide concentration, neither pre- nor post-emergence treatment with the PCL nanocapsules carrying atrazine resulted in the development of any macroscopic symptoms in maize leaves, and there were no impacts on shoot growth. Additionally, no effects were observed when plants were sprayed with PCL nanocapsules without atrazine. Overall, these results suggested that the use of PCL nanocapsules containing atrazine did not lead to persistent side effects in maize plants, and that the technique could offer a safe tool for weed control without affecting

Limitations of predicting in vivo biostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing.

Science.gov (United States)

Padsalgikar, Ajay; Cosgriff-Hernandez, Elizabeth; Gallagher, Genevieve; Touchet, Tyler; Iacob, Ciprian; Mellin, Lisa; Norlin-Weissenrieder, Anna; Runt, James

2015-01-01

Polyurethane biostability has been the subject of intense research since the failure of polyether polyurethane pacemaker leads in the 1980s. Accelerated in vitro testing has been used to isolate degradation mechanisms and predict clinical performance of biomaterials. However, validation that in vitro methods reproduce in vivo degradation is critical to the selection of appropriate tests. High temperature has been proposed as a method to accelerate degradation. However, correlation of such data to in vivo performance is poor for polyurethanes due to the impact of temperature on microstructure. In this study, we characterize the lack of correlation between hydrolytic degradation predicted using a high temperature aging model of a polydimethylsiloxane-based polyurethane and its in vivo performance. Most notably, the predicted molecular weight and tensile property changes from the accelerated aging study did not correlate with clinical explants subjected to human biological stresses in real time through 5 years. Further, DMTA, ATR-FTIR, and SAXS experiments on samples aged for 2 weeks in PBS indicated greater phase separation in samples aged at 85°C compared to those aged at 37°C and unaged controls. These results confirm that microstructural changes occur at high temperatures that do not occur at in vivo temperatures. In addition, water absorption studies demonstrated that water saturation levels increased significantly with temperature. This study highlights that the multiphase morphology of polyurethane precludes the use of temperature accelerated biodegradation for the prediction of clinical performance and provides critical information in designing appropriate in vitro tests for this class of materials. © 2014 Wiley Periodicals, Inc.

In vitro atrazine-exposure inhibits human natural killer cell lytic granule release

International Nuclear Information System (INIS)

Rowe, Alexander M.; Brundage, Kathleen M.; Barnett, John B.

2007-01-01

The herbicide atrazine is a known immunotoxicant and an inhibitor of human natural killer (NK) cell lytic function. The precise changes in NK cell lytic function following atrazine exposure have not been fully elucidated. The current study identifies the point at which atrazine exerts its affect on the stepwise process of human NK cell-mediated lyses of the K562 target cell line. Using intracellular staining of human peripheral blood lymphocytes, it was determined that a 24-h in vitro exposure to atrazine did not decrease the level of NK cell lytic proteins granzyme A, granzyme B or perforin. Thus, it was hypothesized that atrazine exposure was inhibiting the ability of the NK cells to bind to the target cell and subsequently inhibit the release of lytic protein from the NK cell. To test this hypothesis, flow cytometry and fluorescent microscopy were employed to analyze NK cell-target cell co-cultures following atrazine exposure. These assays demonstrated no significant decrease in the level of target cell binding. However, the levels of NK intracellular lytic protein retained and the amount of lytic protein released were assessed following a 4-h incubation with K562 target cells. The relative level of intracellular lytic protein was 25-50% higher, and the amount of lytic protein released was 55-65% less in atrazine-treated cells than vehicle-treated cells following incubation with the target cells. These results indicate that ATR exposure inhibits the ability of NK cells to lyse target cells by blocking lytic granule release without affecting the ability of the NK cell to form stable conjugates with target cells

The degradation behaviour of nine diverse contaminants in urban surface water and wastewater prior to water treatment.

Science.gov (United States)

Cormier, Guillaume; Barbeau, Benoit; Arp, Hans Peter H; Sauvé, Sébastien

2015-12-01

An increasing diversity of emerging contaminants are entering urban surface water and wastewater, posing unknown risks for the environment. One of the main contemporary challenges in ensuring water quality is to design efficient strategies for minimizing such risks. As a first step in such strategies, it is important to establish the fate and degradation behavior of contaminants prior to any engineered secondary water treatment. Such information is relevant for assessing treatment solutions by simple storage, or to assess the impacts of contaminant spreading in the absence of water treatment, such as during times of flooding or in areas of poor infrastructure. Therefore in this study we examined the degradation behavior of a broad array of water contaminants in actual urban surface water and wastewater, in the presence and absence of naturally occurring bacteria and at two temperatures. The chemicals included caffeine, sulfamethoxazole, carbamazepine, atrazine, 17β-estradiol, ethinylestradiol, diclofenac, desethylatrazine and norethindrone. Little information on the degradation behavior of these pollutants in actual influent wastewater exist, nor in general in water for desethylatrazine (a transformation product of atrazine) and the synthetic hormone norethindrone. Investigations were done in aerobic conditions, in the absence of sunlight. The results suggest that all chemicals except estradiol are stable in urban surface water, and in waste water neither abiotic nor biological degradation in the absence of sunlight contribute significantly to the disappearance of desethylatrazine, atrazine, carbamazepine and diclofenac. Biological degradation in wastewater was effective at transforming norethindrone, 17β-estradiol, ethinylestradiol, caffeine and sulfamethoxazole, with measured degradation rate constants k and half-lives ranging respectively from 0.0082-0.52 d(-1) and 1.3-85 days. The obtained degradation data generally followed a pseudo-first-order-kinetic model

Atrazine and Diuron partitioning within a soil-water-surfactant system

Science.gov (United States)

Wang, P.; Keller, A.

2006-12-01

The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

Embryo-larval exposure to atrazine reduces viability and alters oxidative stress parameters in Drosophila melanogaster.

Science.gov (United States)

Figueira, Fernanda Hernandes; Aguiar, Lais Mattos de; Rosa, Carlos Eduardo da

2017-01-01

The herbicide atrazine has been used worldwide with subsequent residual contamination of water and food, which may cause adverse effects on non-target organisms. Animal exposure to this herbicide may affect development, reproduction and energy metabolism. Here, the effects of atrazine regarding survival and redox metabolism were assessed in the fruit fly D. melanogaster exposed during embryonic and larval development. The embryos (newly fertilized eggs) were exposed to different atrazine concentrations (10μM and 100μM) in the diet until the adult fly emerged. Pupation and emergence rates, developmental time and sex ratio were determined as well as oxidative stress parameters and gene expression of the antioxidant defence system were evaluated in newly emerged male and female flies. Atrazine exposure reduced pupation and emergence rates in fruit flies without alterations to developmental time and sex ratio. Different redox imbalance patterns were observed between males and females exposed to atrazine. Atrazine caused an increase in oxidative damage, reactive oxygen species generation and antioxidant capacity and decreased thiol-containing molecules. Further, atrazine exposure altered the mRNA expression of antioxidant genes (keap1, sod, sod2, cat, irc, gss, gclm, gclc, trxt, trxr-1 and trxr-2). Reductions in fruit fly larval and pupal viability observed here are likely consequences of the oxidative stress induced by atrazine exposure. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Short Term Exposure of Atrazine on the Liver and Kidney of Normal and Diabetic Rats

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Dinesh Babu Jestadi

2014-01-01

Full Text Available The present study evaluates the effects of short term (15 days exposure of low dose (300 μg kg−1 of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine on antioxidant status and markers of liver and kidney damage in normal (nondiabetic and diabetic male Wistar rats. Rats were divided into four groups: Group I as normal control, Group II as atrazine treated, Group III as diabetic control, and Group IV as atrazine treated diabetic rats. Atrazine administration resulted in increased MDA concentration as well as increased activities of SOD, CAT, and GPx in both liver and kidney of atrazine treated and atrazine treated diabetic rats. However, GSH level was decreased in both liver and kidney of atrazine treated and atrazine treated diabetic rats. Atrazine administration led to significant increase in liver damage biomarkers such as AST, ALT, and ALP as well as kidney damage biomarkers such as creatinine and urea in both normal and diabetic rats, but this increase was more pronounced in diabetic rats when compared to normal rats. In conclusion, the results of the present study demonstrate that short term exposure of atrazine at a dose of 300 μg kg−1 could potentially induce oxidative damage in liver and kidney of both normal and diabetic rats.

Lixiviação de trifluralin, atrazine e bromacil em três diferentes solos Leaching of trifluralin, atrazine and bromacil in three different soils

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L. H. Signori

1978-01-01

Full Text Available Foi estudada a taxa de lixiviação dos herbicidas trifluralin. atrazine e bromacil em três la. tossolos de texturas diferentes, utilizando-se as doses normais de uso de cada um. Foram utilizadas colunas não deformadas de cada solo e, após a percolação de precipitação simulada de 110 ou 220 mm, semearam-se capim-arroz (Echinochloa cruz-galli (L. Beauv. e alface (Lactuca sativa L. var. La Chaume longitudinalmente nas metades de cada uma. A lixiviação dos herbicidas foi avaliada aos 21 e 33 dias após a semeação. Com indicação dada pelo capim-arroz verificou-se que o trifluralin apresentou lixiviação pequena em quantidade e extensão no perfil, sendo semelhante nos três solos. No solo argiloso e areno-argiloso, com 110 ou 220 mm de chuva, o bromacil apresentou lixiviação bem maior que o atrazine. O bioensaio indicou que as concentrações de bromacil e de atrazine decresciam com a profundidade do perfil. As taxas de lixiviação dos herbicidas foram, de modo geral, proporcionais à sua solubilidade.The leaching rate of trifluralin, atrazine and bromacil in three latossols, with different textures, applying normal dosages of each. was studied. Intact columns of each soil were used and simula ted precip itations of 110 or 220 mm of water, Echinochloa cruz-galli L. Beauv. and Lactuca sativa cv. La Chaume were sown lenghtwise in the two halves of each colum. The leaching rate of the herbic ides was evaluated 21 and 23 days after seedling. With the indication given by E. cruz_galli it was verified that trifluralin showed very little leaching in the soil prof ile, and was similar in the three soils. In the clay and sandy-clay soils with 110 or 220 mm of rain, bromacil showed higher leaching rate than atrazine. In the loamy soil both herbicides showed simila r leaching due to the presence of caulinite, with has a low adsorbing capacity for atrazine. The bio-assay indicated that the bromacil and atrazine concentrations diminished with

Sorption of Atrazine in Tropical Soil by Biochar Prepared from Cassava Waste

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Hui Deng

2014-09-01

Full Text Available Biochar (BC is a carbonaceous and porous product generated from the incomplete combustion of biomass and has been recognized as an efficient adsorbent. This study evaluated the ability of BC to sorb atrazine pesticide in tropical soil, and explored potential environmental values of BC on mitigating organic micro-pollutants. BC was produced from cassava waste via pyrolyzation under oxygen-limiting conditions at 350, 550, and 750 °C (MS350, MS550, and MS750, respectively. Three biochars were characterized and investigated as sorbents for the removal atrazine from tropical soil. BC pyrolyzed at higher temperatures more quickly reached equilibrium. The pseudo-second-order model perfectly simulated the sorption kinetics for atrazine with the coefficients R2 above 0.996, and the sorption amount at equilibrium (qe was 0.016 mg/g for MS350, 0.025 mg/g for MS550 and 0.050 mg/g for MS750. The isotherms of MS350 displayed relatively linear behavior, whereas the sorption of atrazine on MS550 and MS750 followed a nonlinear isotherm. The sorption data were well described by the Freundlich model with logKF of 0.476 for MS350, 0.771 for MS550, 1.865 for MS750. A thermodynamic study indicated that the sorption of atrazine in BC-added soil was a spontaneous and endothermic process and was primarily controlled by physisorption. In addition, lower pH was conducive to the sorption of atrazine in BC-added soil.

The impact of the herbicide atrazine on growth and photosynthesis of seagrass, Zostera marina (L.), seedlings

International Nuclear Information System (INIS)

Gao Yaping; Fang Jianguang; Zhang Jihong; Ren Lihua; Mao Yuze; Li Bin; Zhang Mingliang; Liu Dinghai; Du Meirong

2011-01-01

Highlights: → Impact of the widely used herbicide atrazine on eelgrass seedlings was studied. → Atrazine presents a threat to eelgrass seedlings growth and photosynthesis. → The impact of atrazine on eelgrass seedlings is much higher than for adult plants. - Abstract: The impact of the widely used herbicide atrazine on seedling growth and photosynthesis of eelgrass was determined. The long-term impact of the herbicide atrazine (1, 10 and 100 μg/L) on growth of eelgrass Zostera marina (L.) seedlings, maintained in outdoor aquaria, was monitored over 4 weeks. Exposure to 10 μg/L atrazine resulted in significantly lower plant fresh weight and total chlorophyll concentration and up to 86.67% mortality at the 100 μg/L concentration. Short-term photosynthetic stress on eelgrass seedlings was determined and compared with adult eelgrass using chlorophyll fluorescence. The effective quantum yield in eelgrass seedlings was significantly depressed at all atrazine concentrations (2, 4, 8, 16, 32 and 64 μg/L) even within 2 h and remained at a lower level than for adult plants for each concentration. These results indicate that atrazine presents a potential threat to seagrass seedling functioning and that the impact is much higher than for adult plants.

20 years of long-term atrazine monitoring in a shallow aquifer in western Germany.

Science.gov (United States)

Vonberg, David; Vanderborght, Jan; Cremer, Nils; Pütz, Thomas; Herbst, Michael; Vereecken, Harry

2014-03-01

Atrazine was banned in Germany in 1991 due to findings of atrazine concentrations in ground- and drinking waters exceeding threshold values. Monitoring of atrazine concentrations in the groundwater since then provides information about the resilience of the groundwater quality to changing agricultural practices. In this study, we present results of a monitoring campaign of atrazine concentrations in the Zwischenscholle aquifer. This phreatic aquifer is exposed to intensive agricultural land use and susceptible to contaminants due to a shallow water table. In total 60 observation wells (OWs) have been monitored since 1991, of which 15 are sampled monthly today. Descriptive statistics of monitoring data were derived using the "regression on order statistics" (ROS) data censoring approach, estimating values for nondetects. The monitoring data shows that even 20 years after the ban of atrazine, the groundwater concentrations of sampled OWs remain on a level close to the threshold value of 0.1 μg l(-1) without any considerable decrease. The spatial distribution of atrazine concentrations is highly heterogeneous with OWs exhibiting permanently concentrations above the regulatory threshold on the one hand and OWs were concentrations are mostly below the limit of quantification (LOQ) on the other hand. A deethylatrazine-to-atrazine ratio (DAR) was used to distinguish between diffuse - and point-source contamination, with a global mean value of 0.84 indicating mainly diffuse contamination. Principle Component Analysis (PCA) of the monitoring dataset demonstrated relationships between the metabolite desisopropylatrazine, which was found to be exclusively associated with the parent compound simazine but not with atrazine, and between deethylatrazine, atrazine, nitrate, and the specific electrical conductivity. These parameters indicate agricultural impacts on groundwater quality. The findings presented in this study point at the difficulty to estimate mean concentrations

Acceleration of the herbicide isoproturon degradation in wheat by glycosyltransferases and salicylic acid.

Science.gov (United States)

Lu, Yi Chen; Zhang, Shuang; Yang, Hong

2015-01-01

Isoproturon (IPU) is a herbicide widely used to prevent weeds in cereal production. Due to its extensive use in agriculture, residues of IPU are often detected in soils and crops. Overload of IPU to crops is associated with human health risks. Hence, there is an urgent need to develop an approach to mitigate its accumulation in crops. In this study, the IPU residues and its degradation products in wheat were characterized using ultra performance liquid chromatography-time of fight tandem-mass spectrometer/mass spectrometer (UPLC-TOF-MS/MS). Most detected IPU-derivatives were sugar-conjugated. Degradation and glycosylation of IPU-derivatives could be enhanced by applying salicylic acid (SA). While more sugar-conjugated IPU-derivatives were identified in wheat with SA application, lower levels of IPU were detected, indicating that SA is able to accelerate intracellular IPU catabolism. All structures of IPU-derivatives and sugar-conjugated products were characterized. Comparative data were provided with specific activities and gene expression of certain glucosyltransferases. A pathway with IPU degradation and glucosylation was discussed. Our work indicates that SA-accelerated degradation is practically useful for wheat crops growing in IPU-contaminated soils because such crops with SA application can potentially lower or minimize IPU accumulation in levels below the threshold for adverse effects. Copyright © 2014 Elsevier B.V. All rights reserved.

Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Vanraes, Patrick, E-mail: patrick.vanraes@ugent.be [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Willems, Gert; Nikiforov, Anton [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Surmont, Pieter; Lynen, Frederic [Separation Science Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, 9000 Gent (Belgium); Vandamme, Jeroen; Van Durme, Jim [Research Group Molecular Odor Chemistry, Department of Microbial and Molecular Systems (M2S), KU Leuven, Technology Campus, Gebroeders De Smetstraat 1, 9000 Gent (Belgium); Verheust, Yannick P.; Van Hulle, Stijn W.H.; Dumoulin, Ann [Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, 8500 Kortrijk (Belgium); Leys, Christophe [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium)

2015-12-15

Highlights: • Increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. • Chlorine containing oxidation by-products of first and later generations are detected with HPLC–MS analysis, in agreement with literature. • Desorption analysis shows lower atrazine concentration and higher by-product concentration on activated carbon textile after plasma treatment. • Comparison with plasma reactors described in literature for atrazine decomposition confirms relatively high energy efficiency of our reactor. - Abstract: Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC–MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment.

Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge

International Nuclear Information System (INIS)

Vanraes, Patrick; Willems, Gert; Nikiforov, Anton; Surmont, Pieter; Lynen, Frederic; Vandamme, Jeroen; Van Durme, Jim; Verheust, Yannick P.; Van Hulle, Stijn W.H.; Dumoulin, Ann; Leys, Christophe

2015-01-01

Highlights: • Increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. • Chlorine containing oxidation by-products of first and later generations are detected with HPLC–MS analysis, in agreement with literature. • Desorption analysis shows lower atrazine concentration and higher by-product concentration on activated carbon textile after plasma treatment. • Comparison with plasma reactors described in literature for atrazine decomposition confirms relatively high energy efficiency of our reactor. - Abstract: Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC–MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment.

Adsorption kinetics, isotherms and thermodynamics of atrazine removal using a banana peel based sorbent.

Science.gov (United States)

Chaparadza, Allen; Hossenlopp, Jeanne M

2012-01-01

Atrazine removal from water by treated banana peels was studied. The effect of pH, contact time, initial atrazine concentration, and temperature were investigated. Batch experiments demonstrated that 15 g L(-1) adsorbent dosage removed 90-99% of atrazine from 1-150 ppm aqueous solutions. The removal was both pH and temperature dependent with the most atrazine removed between pH 7 and 8.2 and increased with increasing temperature. Equilibrium data fitted well to the Langmuir and Redlich-Peterson models in the concentration and temperature ranges investigated, with a maximum adsorption capacity of 14 mg g(-1). Simple mass transfer models were applied to the experimental data to examine the adsorption mechanism and it was found that both external mass transfer and intraparticle diffusion played important roles in the adsorption mechanisms. The enthalpy of atrazine adsorption was evaluated to be 67.8 ± 6.3 kJ mol(-l) with a Gibbs free energy of -5.7 ± 1.2 kJ mol(-1).

Watershed regressions for pesticides (WARP) for predicting atrazine concentration in Corn Belt streams

Science.gov (United States)

Stone, Wesley W.; Gilliom, Robert J.

2011-01-01

Watershed Regressions for Pesticides (WARP) models, previously developed for atrazine at the national scale, can be improved for application to the U.S. Corn Belt region by developing region-specific models that include important watershed characteristics that are influential in predicting atrazine concentration statistics within the Corn Belt. WARP models for the Corn Belt (WARP-CB) were developed for predicting annual maximum moving-average (14-, 21-, 30-, 60-, and 90-day durations) and annual 95th-percentile atrazine concentrations in streams of the Corn Belt region. All streams used in development of WARP-CB models drain watersheds with atrazine use intensity greater than 17 kilograms per square kilometer (kg/km2). The WARP-CB models accounted for 53 to 62 percent of the variability in the various concentration statistics among the model-development sites.

Die degradation effect on aging rate in accelerated cycling tests of SiC power MOSFET modules

DEFF Research Database (Denmark)

Luo, Haoze; Baker, Nick; Iannuzzo, Francesco

2017-01-01

In order to distinguish the die and bond wire degradations, in this paper both the die and bond wire resistances of SiC MOSFET modules are measured and tested during the accelerated cycling tests. It is proved that, since the die degradation under specific conditions increases the temperature swing...

Atrazine fate and transport within the coastal zone in southeastern Puerto Rico

Science.gov (United States)

Herbicide transport from crop-land to coastal waters may adversely impact water quality. This work examined potential atrazine impact from use on a farm field adjacent to the Jobos Bay National Estuarine Research Reserve on Puerto Rico’s southeastern coast. Atrazine application was linked to residu...

An iterative method for accelerated degradation testing data of smart electricity meter

Science.gov (United States)

Wang, Xiaoming; Xie, Jinzhe

2017-01-01

In order to evaluate the performance of smart electricity meter (SEM), we must spend a lot of time censoring its status. For example, if we assess to the meter stability of the SEM which needs several years at least according to the standards. So accelerated degradation testing (ADT) is a useful method to assess the performance of the SEM. As we known, the Wiener process is a prevalent method to interpret the performance degradation. This paper proposes an iterative method for ADT data of SEM. The simulation study verifies the application and superiority of the proposed model than other ADT methods.

Rapid treatment of water contaminated with Atrazine and Parathion with sero-valent iron

International Nuclear Information System (INIS)

Rima, Jamil; Amine, Charbel; Ghauch, Antoine; Martin-Bouyer, Michel

1999-01-01

Full text.Experiments were conducted in order to assess the utility of fine-grained iron metal in the remediation of water contaminated with pesticides. The two pesticides that were chosen for this study were Atrazine and Parathion. batch procedures under water treatment conditions (ambient temperature and circumneutral pH) indicated that these pesticides degrade rapidly in the presence of iron powder (40-60 mes, 40 g/L). The decline in the concentration of pesticide was monitored by HPLC analysis supplemented with programmable multiwavelength UV/VIS detector. Experiments were run in buffered solutions. Tests were also performed on an industrial effluent solution containing a variety of pesticides. Our HPLC results indicating the disappearance of all the parent pollutants

The potential protective role of Akropower against Atrazine- induced humoral immunotoxicity in rabbits.

Science.gov (United States)

Morgan, Ashraf M; Ibrahim, Marwa A; Hussien, Ahmed M

2017-12-01

Introduction to the herbicide Atrazine (ATR) can bring about immunotoxicity, aside from other unfavorable results for the creature and human wellbeing. We went for clarifying the genotoxic mechanisms required in humoral immunotoxicity of Gesaprim ® (ATR) and their constriction by Akropwer. Forty rabbits (1.5kg±20%) were utilized and appointed into 4 equal groups. group 1: control; group 2: Received Atrazine at 1/10 LD 50 via food; group 3: Received Akropwer at 1ml/1l/day by means of drinking water; group 4: Received both Atrazine and Akropwer associatively by the same said dosage and course. Atrazine and Akropower exposure were accomplished for 60days. The genotoxic mechanisms of Atrazine- induced humoral immunotoxicity were explained by increased serum total protein and albumin levels, decreased RHDV antibody titer only after four weeks of vaccination and increased level of spleen Fas and Caspase-III genes expression in Atrazine-exposed rabbits. Marked splenocytes apoptosis were detected in the immunohistochemical examination by caspase-III technique and TUNEL assay. Akropower attenuated ATR-induced apoptosis through down-regulation of Fas and Caspase-III genes expression and suppression of their signaling pathway. In conclusion, induction of apoptosis by overexpression of Fas and Caspase-III genes gives a new insight into the mechanism of ATR immunotoxicity. The protective part of Akropower, on the other hand, was characterized by attenuation of Fas and Caspase-III genes mediated apoptosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Menstrual cycle characteristics and reproductive hormone levels in women exposed to atrazine in drinking water.

Science.gov (United States)

Cragin, Lori A; Kesner, James S; Bachand, Annette M; Barr, Dana Boyd; Meadows, Juliana W; Krieg, Edward F; Reif, John S

2011-11-01

Atrazine is the most commonly used herbicide in the U.S. and a wide-spread groundwater contaminant. Epidemiologic and laboratory evidence exists that atrazine disrupts reproductive health and hormone secretion. We examined the relationship between exposure to atrazine in drinking water and menstrual cycle function including reproductive hormone levels. Women 18-40 years old residing in agricultural communities where atrazine is used extensively (Illinois) and sparingly (Vermont) answered a questionnaire (n=102), maintained menstrual cycle diaries (n=67), and provided daily urine samples for analyses of luteinizing hormone (LH), and estradiol and progesterone metabolites (n=35). Markers of exposures included state of residence, atrazine and chlorotriazine concentrations in tap water, municipal water and urine, and estimated dose from water consumption. Women who lived in Illinois were more likely to report menstrual cycle length irregularity (odds ratio (OR)=4.69; 95% confidence interval (CI): 1.58-13.95) and more than 6 weeks between periods (OR=6.16; 95% CI: 1.29-29.38) than those who lived in Vermont. Consumption of >2 cups of unfiltered Illinois water daily was associated with increased risk of irregular periods (OR=5.73; 95% CI: 1.58-20.77). Estimated "dose" of atrazine and chlorotriazine from tap water was inversely related to mean mid-luteal estradiol metabolite. Atrazine "dose" from municipal concentrations was directly related to follicular phase length and inversely related to mean mid-luteal progesterone metabolite levels. We present preliminary evidence that atrazine exposure, at levels below the US EPA MCL, is associated with increased menstrual cycle irregularity, longer follicular phases, and decreased levels of menstrual cycle endocrine biomarkers of infertile ovulatory cycles. Copyright © 2011 Elsevier Inc. All rights reserved.

Species-dependent effects of biochar amendment on bioaccumulation of atrazine in earthworms

International Nuclear Information System (INIS)

Wang, Fang; Ji, Rong; Jiang, Zhongwei; Chen, Wei

2014-01-01

We observed that at a contamination level of 4.25 mg-atrazine/kg-soil, the biota–soil accumulation factor (BSAF) for the anecic M. guillelmi is approximately 5 times that for the epigeic E. foetida. This is attributable to the fact that bio-uptake by E. foetida is mainly through dermal absorption, whereas bio-uptake by M. guillelmi is largely affected by the gut processes, through which the physical grinding and surfactant-like materials facilitate the desorption of atrazine from soil. Strikingly, biochar amendment resulted in much greater reduction in BSAF for M. guillelmi than for E. foetida. At a biochar dose of 0.5% (wt:wt) the difference in BSAF between the two species became much smaller, and at a dose of 2% no statistical difference was observed. A likely explanation is that gut processes by M. guillelmi were much less effective in extracting atrazine from the biochar (the predominant phase wherein atrazine resided) than from soil particles. -- Highlights: • Greater bio-uptake was observed for anecic M. guillelmi than for epigeic E. foetida. • Gut processes of M. guillelmi can facilitate desorption of contaminants from soil. • Biochar amendment caused greater reduction in bioaccumulation for M. guillelmi. • Gut processes are much less effective in extracting atrazine from biochar. -- Amendment of contaminated soils/sediments with biochar is more effective for earthworm species with greater bioaccumulation capabilities

Study of Operating Parameters for Accelerated Anode Degradation in SOFCs

DEFF Research Database (Denmark)

Ploner, Alexandra; Hagen, Anke; Hauch, Anne

2017-01-01

Solid oxide fuel cell (SOFC) applications require lifetimes of several years on the system level. A big challenge is to demonstrate such exceptionally long lifetimes in ongoing R&D projects. Accelerated or compressed testing are alternative methods to obtain this. Activities in this area have been...... carried out without arriving at a generally accepted methodology. This is mainly due to the complexity of degradation mechanisms on the single SOFC components as function of operating parameters. In this study, we present a detailed analysis of approx. 180 durability tests regarding degradation of single...... SOFC components as function of operating conditions. Electrochemical impedance data were collected on the fresh and long-term tested SOFCs and used to de-convolute the individual losses of single SOFC cell components – electrolyte, cathode and anode. The main findings include a time-dependent effect...

Enzymatic vegetable organic extracts as soil biochemical biostimulants and atrazine extenders.

Science.gov (United States)

García-Martínez, Ana María; Tejada, Manuel; Díaz, Ana Isabel; Rodríguez-Morgado, Bruno; Bautista, Juan; Parrado, Juan

2010-09-08

The purpose of this study was to gather information on the potential effects of organic biostimulants on soil activity and atrazine biodegradation. Carob germ enzymatic extract (CGEE) and wheat condensed distiller solubles enzymatic extract (WCDS-EE) have been obtained using an enzymatic process; their main organic components are soluble carbohydrates and proteins in the form of peptides and free amino acids. Their application to soil results in high biostimulation, rapidly increased dehydrogenase, phosphatase and glucosidase activities, and an observed atrazine extender capacity due to inhibition of its mineralization. The extender capacity of both extracts is proportional to the protein/carbohydrate ratio content. As a result, these enzymatic extracts are highly microbially available, leading to two independent phenomena, fertility and an atrazine persistence that is linked to increased soil activity.

Immunomodulatory effects of maternal atrazine exposure on male Balb/c mice

International Nuclear Information System (INIS)

Rowe, Alexander M.; Brundage, Kathleen M.; Schafer, Rosana; Barnett, John B.

2006-01-01

Atrazine is a widely used herbicide applied to corn, sugar and other crops as a broad leaf weed inhibitor. Using the Balb/c mouse model, we have determined that prenatal/lactational exposure to atrazine alters adult immune function. Pregnant Balb/c dams were exposed subcutaneously for 21 days via time release pellets to 700 μg per day of atrazine beginning between days 10 and 12 of pregnancy. Prenatal/Lactational exposure caused no overt physical malformations in the offspring and had no effect on the number of litters carried to term or the litter size. Upon reaching early adulthood (approximately 3 months of age), the state of their immune system was evaluated. There were no changes in body weight or in the organ to body weight ratio of the spleen. Additionally, no changes were observed in the number of CD8 + T cell, CD4 + T cell, or B220 + B cell subpopulations in the spleen. T cell function was assessed by measuring proliferation and cytolytic activity after in vitro allogeneic stimulation. Male mice which had been prenatally/lactationally exposed to atrazine had an increase in both T cell proliferation and cytolytic activity. The humoral immune response was assessed after immunization with heat killed Streptococcus pneumoniae (HKSP). There was a significant increase in the number of HKSP-specific IgM secreting B cells in the spleen of prenatal/lactational exposed male mice. Inasmuch as atrazine is a widespread environmental contaminant, this immunopotentiation raises concerns that it may potentiate clinical diseases, such as autoimmune disease and hypersensitivity, and needs to be carefully monitored and studied

Microscopic examination on cytological changes in Allium cepa and shift in phytoplankton population at different doses of Atrazine

Science.gov (United States)

Ghosh, Nabarun; Finger, Kristen; Usnick, Samantha; Rogers, William J.; Das, A. B.; Smith, Don W.

2010-06-01

Atrazine is a wide-range herbicide. For over 50 years, atrazine has been used as a selective broadleaf herbicide in many capacities, from pre-plant to pre-emergence to post-emergence, depending on the crop and application. Currently, 96% of all atrazine used is for commercial applications in fields for the control of broadleaf and grassy weeds in crops such as sorghum, corn, sugarcane, pineapple and for the control of undesirable weeds in rangeland. Many panhandle wells have also detected atrazine in samples taken. The concern for the public is the long-term effect of atrazine with its increasing popularity, and the impact on public health. We investigated the effect of different concentrations of atrazine on Allium cepa (onion), a standard plant test system. We established a control with the Allium bulbs grown on hydroponics culture. Varying concentrations of atrazine was used on the standard plant test system, Allium cepa grown hydroponically. The mitotic indices varied and with higher doses, we observed various chromosomal abnormalities including sticky bridges, early and late separations, and lag chromosomes with higher doses of treatments. In the second part of the experiment, 0.1ppb, 1ppb, 10ppb, and 100ppb concentrations of atrazine were applied to established phytoplankton cultures from the Lake Tanglewood, Texas. Study with a Sedgwick-Rafter counter, a BX-40 Olympus microscope with DP-70 camera revealed a gradual shift in the phytoplankton community from obligatory to facultative autotroph and finally to a parasitic planktonic community. This explains the periodic fish kill in the lakes after applications of atrazine in crop fields.

Atrazine Molecular Imprinted Polymers: Comparative Analysis by Far-Infrared and Ultraviolet Induced Polymerization

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Jun Chen

2014-01-01

Full Text Available Atrazine molecular imprinted polymers (MIPs were comparatively synthesized using identical polymer formulation by far-infrared (FIR radiation and ultraviolet (UV-induced polymerization, respectively. Equilibrium binding experiments were carried out with the prepared MIPs; the results showed that MIPuv possessed specific binding to atrazine compared with their MIPFIR radiation counterparts. Scatchard plot’s of both MIPs indicated that the affinities of the binding sites in MIPs are heterogeneous and can be approximated by two dissociation-constants corresponding to the high- and low-affinity binding sites. Moreover, several common pesticides including atrazine, cyromazine, metamitron, simazine, ametryn, terbutryn were tested to determine their specificity, similar imprinting factor (IF and different selectivity index (SI for both MIPs. Physical characterization of the polymers revealed that the different polymerization methods led to slight differences in polymer structures and performance by scanning electron microscope (SEM, Fourier transform infrared absorption (FT-IR, and mercury analyzer (MA. Finally, both MIPs were used as selective sorbents for solid phase extraction (SPE of atrazine from lake water, followed by high performance liquid chromatography (HPLC analysis. Compared with commercial C18 SPE sorbent (86.4%–94.8%, higher recoveries of atrazine in spiked lake water were obtained in the range of 90.1%–97.1% and 94.4%–101.9%, for both MIPs, respectively.

Atrazine Contamination and Potential Health Effects on Freshwater Mussel Uniandra contradens Living in Agricultural Catchment at Nan Province, Thailand

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Tongchai Thitiphuree

2013-01-01

Full Text Available Seasonal cultivation in northern part of Thailand leads to widely uses of agrochemicals especially atrazine herbicide. To examine whether an intensive use of atrazine could lead to contamination in aquatic environment, sediment and water were collected from an agricultural catchment in Nan Province during 2010-2011 and subjected to analysis for atrazine by GC-MS. The results showed that detectable levels of atrazine were found in water (0.16 µg/ml and sediment (0.23 µg/g of the catchment. To monitor potential effects of atrazine on aquatic animals, a freshwater mussel Uniandra contradens was used as a sentinel species for bioaccumulation and potential health effects. Mussels collected from the catchment during 2010-2011 were subjected to analysis for atrazine residue in tissue and condition factor based on body weight and shell length. The results showed that detectable levels of atrazine were found in mussel tissue with the highest level (8.40  2.06 ng/g in late wet season when runoff from heavy rain was evidenced. Condition factor, an indicative of overall health, showed a significant negative correlation with atrazine residue in the tissue. This information could be used as part of the monitoring program for herbicide contamination and potential health effects in agricultural environment.

Watershed regressions for pesticides (warp) models for predicting atrazine concentrations in Corn Belt streams

Science.gov (United States)

Stone, Wesley W.; Gilliom, Robert J.

2012-01-01

Watershed Regressions for Pesticides (WARP) models, previously developed for atrazine at the national scale, are improved for application to the United States (U.S.) Corn Belt region by developing region-specific models that include watershed characteristics that are influential in predicting atrazine concentration statistics within the Corn Belt. WARP models for the Corn Belt (WARP-CB) were developed for annual maximum moving-average (14-, 21-, 30-, 60-, and 90-day durations) and annual 95th-percentile atrazine concentrations in streams of the Corn Belt region. The WARP-CB models accounted for 53 to 62% of the variability in the various concentration statistics among the model-development sites. Model predictions were within a factor of 5 of the observed concentration statistic for over 90% of the model-development sites. The WARP-CB residuals and uncertainty are lower than those of the National WARP model for the same sites. Although atrazine-use intensity is the most important explanatory variable in the National WARP models, it is not a significant variable in the WARP-CB models. The WARP-CB models provide improved predictions for Corn Belt streams draining watersheds with atrazine-use intensities of 17 kg/km2 of watershed area or greater.

Biodegradation of 14 C-atrazine under outdoor conditions

International Nuclear Information System (INIS)

Queiroz, Brigida Pimentel Villar de

1997-10-01

Uniformly 14 C-ring labeled atrazine (5 L/ha) was applied to a Typical Hapludox Brazilian Soil sample which was incubated under outdoor conditions. Sample of 200 g (dry weight base) of fresh soil were distributed in Erlenmeyer flasks and the moisture was adjusted for 2/3 rds of the soil field capacity. The flasks were then buried in the Lysimeter Station when they were incubated. The experiment started jointly with a corn planting. The 14 C O 2 was analyzed every 15 day, during a period of 150 days. The desorbed, extracted and bound residues were analyzed. The extracted soil was fractionated and the residues in the humin, fulvic and humic acids were determined. At the end of the incubation period (150 days), the 14 CO 2 evolved reached up to 36% of the total applied activity, the bound residues were detected in about the same (34%) during the inoculation period, and were distributed in the fractions of fulvic acids (29,91%), humic acids (6,83%) and humin (63,26%). The metabolites formed in the desorbed residues and in the extracted residues were determined using thin layer chromatography with 14 C-detector. After 150 days incubation, desorbed soil residues were identified as atrazine (52,72%), hydroxiatrazine (44%) and desisopropilatrazine (3,28%). The extractable residues contained atrazine (79,29%), hydroxiatrazine (16,22%), desisopropilatrazine (2,25%) and desetylatrazine (2,24%). (author)

Effects of environmentally relevant concentrations of atrazine on gonadal development of snapping turtles (Chelydra serpentina).

Science.gov (United States)

de Solla, Shane R; Martin, Pamela A; Fernie, Kimberly J; Park, Brad J; Mayne, Gregory

2006-02-01

The herbicide atrazine has been suspected of affecting sexual development by inducing aromatase, resulting in the increased conversion of androgens to estrogens. We used snapping turtles (Chelydra serpentina), a species in which sex is dependent on the production of estrogen through aromatase activity in a temperature-dependent manner, to investigate if environmentally relevant exposures to atrazine affected gonadal development. Eggs were incubated in soil to which atrazine was applied at a typical field application rate (3.1 L/ha), 10-fold this rate (31 L/ha), and a control rate (no atrazine) for the duration of embryonic development. The incubation temperature (25 degrees C) was selected to produce only males. Although some males with testicular oocytes and females were produced in the atrazine-treated groups (3.3-3.7%) but not in the control group, no statistical differences were found among treatments. Furthermore, snapping turtle eggs collected from natural nests in a corn field were incubated at the pivotal temperature (27.5 degrees C) at which both males and females normally would be produced, and some males had oocytes in the testes (15.4%). The presence of low numbers of males with oocytes may be a natural phenomenon, and we have limited evidence to suggest that the presence of normal males with oocytes may represent a feminizing effect of atrazine. Histological examination of the thyroid gland revealed no effect on thyroid morphology.

Effects of atrazine on endocrinology and physiology in juvenile barramundi, Lates calcarifer (Bloch).

Science.gov (United States)

Kroon, Frederieke J; Hook, Sharon E; Jones, Dean; Metcalfe, Suzanne; Osborn, Hannah L

2014-07-01

Exposure to certain environmental contaminants such as agricultural pesticides can alter normal endocrine and reproductive parameters in wild fish populations. Recent studies have found widespread pesticide contamination across the rivers that discharge into the Great Barrier Reef lagoon. Potential impacts on native fish species exposed to known endocrine disrupting chemicals such as atrazine, simazine, and diuron have not been assessed. In the present study, the authors examined the endocrine and physiological effects of short-term, acute exposure of environmentally relevant concentrations of analytical grade atrazine in juvenile barramundi (Lates calcarifer) in a controlled laboratory experiment. Expression of hepatic vitellogenin was not affected, supporting results of previous studies that showed that atrazine does not have a direct estrogenic effect via mediation of estrogen receptors. The lack of effect on brain cytochrome P19B (CYP19B) expression levels, combined with increases in testosterone (T) and 17β estradiol and a stable T:17β estradiol ratio, does not support the hypothesis that atrazine has an indirect estrogenic effect via modulation of aromatase expression. Gill ventilation rate, a measure of oxidative stress, did not change in contrast to other studies finding enhanced osmoregulatory disturbance and gill histopathology after atrazine exposure. To more closely reflect field conditions, the authors recommend that laboratory studies should focus more on examining the effects of commercial pesticide formulations that contain additional ingredients that have been found to be disruptive to endocrine function. © 2014 SETAC.

The impact of the herbicide atrazine on growth and photosynthesis of seagrass, Zostera marina (L.), seedlings.

Science.gov (United States)

Gao, Yaping; Fang, Jianguang; Zhang, Jihong; Ren, Lihua; Mao, Yuze; Li, Bin; Zhang, Mingliang; Liu, Dinghai; Du, Meirong

2011-08-01

The impact of the widely used herbicide atrazine on seedling growth and photosynthesis of eelgrass was determined. The long-term impact of the herbicide atrazine (1, 10 and 100 μg/L) on growth of eelgrass Zostera marina (L.) seedlings, maintained in outdoor aquaria, was monitored over 4 weeks. Exposure to 10 μg/L atrazine resulted in significantly lower plant fresh weight and total chlorophyll concentration and up to 86.67% mortality at the 100 μg/L concentration. Short-term photosynthetic stress on eelgrass seedlings was determined and compared with adult eelgrass using chlorophyll fluorescence. The effective quantum yield in eelgrass seedlings was significantly depressed at all atrazine concentrations (2, 4, 8, 16, 32 and 64 μg/L) even within 2 h and remained at a lower level than for adult plants for each concentration. These results indicate that atrazine presents a potential threat to seagrass seedling functioning and that the impact is much higher than for adult plants. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Effects of atrazine on fish, amphibians, and aquatic reptiles: a critical review.

Science.gov (United States)

Solomon, Keith R; Carr, James A; Du Preez, Louis H; Giesy, John P; Kendall, Ronald J; Smith, Ernest E; Van Der Kraak, Glen J

2008-01-01

The herbicide atrazine is widely used in agriculture for the production of corn and other crops. Because of its physical and chemical properties, atrazine is found in small concentrations in surface waters--habitats for some species. A number of reports on the effects of atrazine on aquatic vertebrates, mostly amphibians, have been published, yet there is inconsistency in the effects reported, and inconsistency between studies in different laboratories. We have brought the results and conclusions of all of the relevant laboratory and field studies together in this critical review and assessed causality using procedures for the identification of causative agents of disease and ecoepidemiology derived from Koch's postulates and the Bradford-Hill guidelines. Based on a weight of evidence analysis of all of the data, the central theory that environmentally relevant concentrations of atrazine affect reproduction and/or reproductive development in fish, amphibians, and reptiles is not supported by the vast majority of observations. The same conclusions also hold for the supporting theories such as induction of aromatase, the enzyme that converts testosterone to estradiol. For other responses, such as immune function, stress endocrinology, parasitism, or population-level effects, there are no indications of effects or there is such a paucity of good data that definitive conclusions cannot be made.

Epidermal transmittance and phenolic composition in leaves of atrazine-tolerant and atrazine-sensitive cultivars of Brassica napus grown under enhanced UV-B radiation

International Nuclear Information System (INIS)

Olsson, L.C.; Veit, M.; Bornman, J.F.

1999-01-01

Experiments were conducted on the atrazine-tolerant mutant Stallion and the atrazine-sensitive cv. Paroll of Brassica napus L., which were grown under either visible light or with the addition of UV-B radiation (280–320 nm) for 15 days. The mutant has been shown to be sensitive to high levels of visible light as compared to the atrazine-sensitive cultivar and therefore we wished to determine plant response to UV-B radiation with respect to potential pigment changes, certain anatomical features, radiation penetration and partial photosynthesis. With regard to pigment changes, we were particularly interested in whether the compositional shift in flavonol pigments under enhanced UV-B radiation, previously suggested to favour increased antioxidant activity, is confined to the adaxial epidermis, which generally receives most UV-B radiation or whether the pigment shift is also inducible in the abaxial epidermis.As was to be expected, the penetration of UV-B radiation (310 nm) was lower in the UV-B-exposed plants, which was correlated with an increased amount of UV-screening pigments in the adaxial and abaxial epidermal layers. The main flavonoid glycosides showed the largest shift from kaempferol to quercetin as aglycone moiety in the adaxial epidermal layer. However, in the abaxial epidermal layer the hydroxycinnamic acid (HCA) derivatives and kaempferol glycosides were predominant. Penetration of 430 nm light was higher after UV-B exposure, and probably contributed to the fact that photosynthetic efficiency of photosystem II was unchanged or higher after UV-B exposure. UV-B radiation decreased leaf area in the atrazine-tolerant mutant only. Both cultivars showed an increased leaf thickness after UV-B exposure due to cell elongation mainly of the palisade tissue. This was especially evident in the mutant

Examining the joint toxicity of chlorpyrifos and atrazine in the aquatic species: Lepomis macrochirus, Pimephales promelas and Chironomus tentans

International Nuclear Information System (INIS)

Tyler Mehler, W.; Schuler, Lance J.; Lydy, Michael J.

2008-01-01

The joint toxicity of chlorpyrifos and atrazine was compared to that of chlorpyrifos alone to discern any greater than additive response using both acute toxicity testing and whole-body residue analysis. In addition, acetylcholinesterase (AChE) inhibition and biotransformation were investigated to evaluate the toxic mode of action of chlorpyrifos in the presence of atrazine. The joint toxicity of atrazine and chlorpyrifos exhibited no significant difference in Lepomis macrochirus compared to chlorpyrifos alone; while studies performed with Pimephales promelas and Chironomus tentans, did show significant differences. AChE activity and biotransformation showed no significant differences between the joint toxicity of atrazine and chlorpyrifos and that of chlorpyrifos alone. From the data collected, the combination of atrazine and chlorpyrifos pose little additional risk than that of chlorpyrifos alone to the tested fish species. - The joint toxicity between atrazine and chlorpyrifos caused greater than additive responses in invertebrates, but the interactions in vertebrates was less pronounced

Examining the joint toxicity of chlorpyrifos and atrazine in the aquatic species: Lepomis macrochirus, Pimephales promelas and Chironomus tentans

Energy Technology Data Exchange (ETDEWEB)

Tyler Mehler, W.; Schuler, Lance J. [Fisheries and Illinois Aquaculture Center and Department of Zoology, Southern Illinois University at Carbondale, Carbondale, IL 62901-6511 (United States); Lydy, Michael J. [Fisheries and Illinois Aquaculture Center and Department of Zoology, Southern Illinois University at Carbondale, Carbondale, IL 62901-6511 (United States)], E-mail: mlydy@siu.edu

2008-03-15

The joint toxicity of chlorpyrifos and atrazine was compared to that of chlorpyrifos alone to discern any greater than additive response using both acute toxicity testing and whole-body residue analysis. In addition, acetylcholinesterase (AChE) inhibition and biotransformation were investigated to evaluate the toxic mode of action of chlorpyrifos in the presence of atrazine. The joint toxicity of atrazine and chlorpyrifos exhibited no significant difference in Lepomis macrochirus compared to chlorpyrifos alone; while studies performed with Pimephales promelas and Chironomus tentans, did show significant differences. AChE activity and biotransformation showed no significant differences between the joint toxicity of atrazine and chlorpyrifos and that of chlorpyrifos alone. From the data collected, the combination of atrazine and chlorpyrifos pose little additional risk than that of chlorpyrifos alone to the tested fish species. - The joint toxicity between atrazine and chlorpyrifos caused greater than additive responses in invertebrates, but the interactions in vertebrates was less pronounced.

Assessment of atrazine levels in Kintampo-North and Techiman municipalities in the Brong Ahafo Region of Ghana

International Nuclear Information System (INIS)

Kwarteng, L.

2013-06-01

Successes in Ghana's agriculture and saving lives from vector borne diseases would not have happened without the application of pesticides. The increasing maize farming activities in the Techiman and Kintampo-North Municipalities of the Brong-Ahafo Region have resulted in a corresponding increase in atrazine usage. The presence of pesticides in the environment and food impacts negatively on human health and create barriers to trade in agricultural commodities. Atrazine is a herbicide of concern because of its persistent in the environment. There is growing evidence of cacinogenicity, genotoxicity and endocrine disruption capacity being attributed to the ingestion of or exposure to atrazine. In this study a field survey was conducted to assess farmers' knowledge of safe handling and use of pesticides. The study also evaluated the levels of atrazine in soil at different depth and water from the study area using Gas Chromatography/Mass Spectrometry (GC/MS) and also assessed the potential health risk associated with atrazine contamination of water in the Techiman and Kintampo North Municipalities. Generally a high proportion of farmers were at a high risk of pesticide poisoning from occupational exposure. More than 80% of farmers did not practice safety precautions during pesticide mixing and application leading to considerable prevalence of pesticide related illness in this agricultural community. Atrazine residues were detected in 20% of the total soil samples analysed and the levels ranged between 0.001µg/Kg and 0.011µg/Kg. The estimated doses of atrazine do not pose any direct hazard to human health although present in water samples. Although residue levels of atrazine were low the results implicitly revealed that improper pesticide use in the study area has led to contamination of soil and poor water quality. (au)

Evaluation of the agronomic performance of atrazine-tolerant transgenic japonica rice parental lines for utilization in hybrid seed production.

Directory of Open Access Journals (Sweden)

Luhua Zhang

Full Text Available Currently, the purity of hybrid seed is a crucial limiting factor when developing hybrid japonica rice (Oryza sativa L.. To chemically control hybrid seed purity, we transferred an improved atrazine chlorohydrolase gene (atzA from Pseudomonas ADP into hybrid japonica parental lines (two maintainers, one restorer, and Nipponbare, by using Agrobacterium-mediated transformation. We subsequently selected several transgenic lines from each genotype by using PCR, RT-PCR, and germination analysis. In the presence of the investigated atrazine concentrations, particularly 150 µM atrazine, almost all of the transgenic lines produced significantly larger seedlings, with similar or higher germination percentages, than did the respective controls. Although the seedlings of transgenic lines were taller and gained more root biomass compared to the respective control plants, their growth was nevertheless inhibited by atrazine treatment compared to that without treatment. When grown in soil containing 2 mg/kg or 5 mg/kg atrazine, the transgenic lines were taller, and had higher total chlorophyll contents than did the respective controls; moreover, three of the strongest transgenic lines completely recovered after 45 days of growth. After treatment with 2 mg/kg or 5 mg/kg of atrazine, the atrazine residue remaining in the soil was 2.9-7.0% or 0.8-8.7% respectively, for transgenic lines, and 44.0-59.2% or 28.1-30.8%, respectively, for control plants. Spraying plants at the vegetative growth stage with 0.15% atrazine effectively killed control plants, but not transgenic lines. Our results indicate that transgenic atzA rice plants show tolerance to atrazine, and may be used as parental lines in future hybrid seed production.

Exposure to Atrazine and Selected Non-Persistent Pesticides among Corn Farmers during a Growing Season

Science.gov (United States)

Bakke, Berit; De Roos, Anneclaire J.; Barr, Dana B.; Stewart, Patricia A.; Blair, Aaron; Freeman, Laura Beane; Lynch, Charles F.; Allen, Ruth H.; Alavanja, Michael C.R.; Vermeulen, Roel

2011-01-01

Objectives The aim was to develop quantitative estimates of farmers’ pesticide exposure to atrazine and to provide an overview of background levels of selected non-persistent pesticides among corn farmers in a longitudinal molecular epidemiologic study. Methods The study population consisted of 30 Agricultural Health Study farmers from Iowa and 10 nonfarming controls. Farmers completed daily and weekly diaries from March to November in 2002 and 2003 on pesticide use and other exposure determinants. Urine samples were collected at 10 timepoints relative to atrazine application and other farming activities. Pesticide exposure was assessed using urinary metabolites and diaries. Results The analytical limit of detection (LOD) ranged between 0.1–0.2 μg/l for all pesticide analytes except for isazaphos (1.5 μg/l) and diazinon (0.7 μg/l). Farmers had higher geometric mean urinary atrazine mercapturate (AZM) values than controls during planting (1.1 vs. urine collection (38% vs. 6%, p<0.0001). A similar pattern was observed for 2,4-D and acetochlor (92% vs. 47%, p<0.0001 and 45% vs. 4%, p<0.0001, respectively). Conclusion Urinary AZM levels in farmers were largely driven by recent application of atrazine. Therefore, the amount of atrazine applied is likely to provide valid surrogates of atrazine exposure in epidemiologic studies. Elevated background levels of non-persistent pesticides, especially 2,4-D, indicate importance in epidemiologic studies of capturing pesticide exposures that might not be directly related to the actual application. PMID:19052531

Genotoxic Effect of Atrazine, Arsenic, Cadmium and Nitrate ...

African Journals Online (AJOL)

Atrazine has clastogenic effects and may also act as tumor promoter as it induces the aromatase enzyme. ... bladder cancer. This study ... in MCF-10A cells, suggesting that estrogen receptor modulated the genotoxicity of estrogen. Cd caused ...

Fish short-term reproduction assay with atrazine and the Japanese medaka (Oryzias latipes).

Science.gov (United States)

Hosmer, Alan J; Schneider, Suzanne Z; Anderson, Julie C; Knopper, Loren D; Brain, Richard A

2017-09-01

Breeding groups of Japanese medaka (Oryzias latipes) were exposed to atrazine at measured concentrations of 0.6, 5.5, and 53 μg/L for 35 d. Evaluated endpoints included survival, fecundity, fertility, growth (weight and length), behavior, secondary sex characteristics (anal fin papillae), gonad histopathology, and hepatic vitellogenin. No statistically significant effects of atrazine exposure on survival and growth of medaka were noted during the test, and mean survival was ≥97.5% in all treatment groups on day 35. No significant effects of atrazine exposure on reproduction were observed. The number of mean cumulative eggs produced in the negative control and the 0.6, 5.5, and 53 μg/L treatment groups was 7158, 6691, 6883, and 6856, respectively. The mean number of eggs per female reproductive day was 40.9, 38.2, 40.2, and 39.2, respectively. There were also no dose-dependent effects on mean anal fin papillae counts among male fish or expression of vtg-II in males or females. In addition, atrazine exposure was not related to the developmental stage of test fish, with testes stages ranging from 2 to 3 in all groups and ovaries ranging from stage 2 to 2.5. Overall, exposure to atrazine up to 53 µg/L for 35 d did not result in significant, treatment-related effects on measured endpoints related to survival, growth, or reproduction in Japanese medaka. Environ Toxicol Chem 2017;36:2327-2334. © 2017 SETAC. © 2017 SETAC.

Impact of long-term wastewater irrigation on sorption and transport of atrazine in Mexican agricultural soils

OpenAIRE

Muller, K.; Duwig, Céline; Prado, B.; Siebe, C.; Hidalgo, C.; Etchevers, J.

2012-01-01

In the Mezquital Valley, Mexico, crops have been irrigated with untreated municipal wastewater for more than a century. Atrazine has been applied to maize and alfalfa grown in the area for weed control for 15 years. Our objectives were to analyse (i) how wastewater irrigation affects the filtering of atrazine, and (ii) if the length of irrigation has a significant impact. We compared atrazine sorption to Phaeozems that have been irrigated with raw wastewater for 35 (P35) and 85 (P85) years wi...

Mechanical properties of electrospun PCL scaffold under in vitro and accelerated degradation conditions

DEFF Research Database (Denmark)

Løvdal, Alexandra Liv Vest; Vange, Jakob; Nielsen, Lene Feldskov

2014-01-01

Within recent years, researchers have looked into using polycaprolactone (PCL) as a synthetic biodegradable scaffold for tissue engineering purposes. This study investigated the mechanical properties of an electrospun PCL, while being exposed to physiological fluids at 37C (in vitro conditions) w...... in buffer (pH 12). The accelerated study showed a linear decrease in both elastic modulus and yield stress as a function of degradation time....

Atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi

OpenAIRE

Elgueta, Sebastian; Santos, Cledir; Santos, C.; Lima, Nelson; Diez, M. C.

2016-01-01

Due to the environmental concerns about the herbicide atrazine accumulation in food products and water reservoirs, there is a need to develop safe and economical methods for its dissipation. The main aim of this study was to evaluate the atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi in a pelletized support (PS). All fungal isolates evaluated were efficient in colonizing the surface and inner parts of the PS and without differences observed in the coloniza...

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons

International Nuclear Information System (INIS)

Flores de Jesus, I.

2003-01-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Atrazine in public water supplies and risk of ovarian cancer among postmenopausal women in the Iowa Women's Health Study.

Science.gov (United States)

Inoue-Choi, Maki; Weyer, Peter J; Jones, Rena R; Booth, Benjamin J; Cantor, Kenneth P; Robien, Kim; Ward, Mary H

2016-09-01

Few studies have evaluated environmental chemical exposures in relation to ovarian cancer. We previously found an increased risk of ovarian cancer among postmenopausal women in Iowa associated with higher nitrate levels in public water supplies (PWS). However, elevated nitrate levels may reflect the presence of other agricultural chemicals, such as atrazine, one of the most commonly detected pesticides in Iowa PWS. We evaluated the association between atrazine in drinking water and incident ovarian cancer (N=145, 1986-2010) among 13 041 postmenopausal women in the Iowa Women's Health Study who used their PWS for ≥11 years as reported in 1989. Average levels of atrazine (1986-1987), nitrate-nitrogen (NO3-N, 1955-1988) and estimated levels of total trihalomethanes (TTHM, 1955-1988) from PWS monitoring data were linked to the participants' cities of residence. We computed HRs and 95% CIs by categories of the average atrazine level (not detected, ≤ or >0.37 parts per billion=median) using Cox proportional hazards regression adjusting for ovarian cancer risk factors. Atrazine was detected in water samples from 69 cities where 4155 women (32%) lived and levels were moderately correlated with NO3-N (ρ=0.35) and TTHM (ρ=0.24). Atrazine levels were not associated with ovarian cancer risk with or without adjusting for NO3-N and TTHM levels (p-trend=0.50 and 0.81, respectively). Further, there was no evidence for effect modification of the atrazine association by NO3-N or TTHM levels. In our study with low atrazine detection rates, we found no association between atrazine in PWS and postmenopausal ovarian cancer risk. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Properties comparison of biochars from corn straw with different pretreatment and sorption behaviour of atrazine.

Science.gov (United States)

Zhao, Xuchen; Ouyang, Wei; Hao, Fanghua; Lin, Chunye; Wang, Fangli; Han, Sheng; Geng, Xiaojun

2013-11-01

Biochar has been recognised as an efficient pollution control material. In this study, biochars (CS450 and ADPCS450) were produced using corn straw with different pretreatment techniques (without and with ammonium dihydrogen phosphate (ADP)). The character of the two biochars was compared using elemental analysis, specific surface area (SSA) and Fourier transform infrared spectra (FTIR). ADPCS450 had a higher residue yield and a much larger specific surface area than CS450. The Freundlich, Langmuir and Redlich-Peterson models were used to interpret the sorption behaviour of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), and the results fit the Redlich-Peterson equation best. The isothermal sorption parameters indicated that the sorption capacity of atrazine on ADPCS450 was much larger than the sorption capacity of atrazine on CS450. Atrazine sorption was also favoured in acidic solution and under higher temperature conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Spectrophotometric and visual detection of the herbicide atrazine by exploiting hydrogen bond-induced aggregation of melamine-modified gold nanoparticles

International Nuclear Information System (INIS)

Liu, Guangyang; Yang, Xin; Zhang, Yanxin; Zhou, Pan; Li, Tengfei; Yu, Hailong; Du, Xinwei; She, Yongxin; Wang, Jing; Wang, Shanshan; Jin, Fen; Jin, Maojun; Shao, Hua; Zheng, Lufei

2015-01-01

We report on a method for the determination of the herbicide atrazine in tap water samples using melamine-modified gold nanoparticles (Mel-AuNPs). If a solution containing atrazine is added to a solution of such NPs, a color change occurs from wine-red to blue. This is due to a transition from monodisperse to aggregated Mel-AuNPs and caused by strong hydrogen bonding between atrazine and melamine. The color change can be monitored by a UV–vis spectrophotometer or with bare eyes. The ratio of the absorbances at 640 and 523 nm is linearly related to the logarithm of the atrazine concentration in the 0.165 to 16.5 μM range, and (with different slope) in the 16.5 μM to 330 μM range. The detection limit of atrazine is as low as 16.5 nM (S/N = 3). The method was successfully applied to the determination of atrazine in spiked tap water and gave recoveries that ranged from 72.5 % to 102.3 %. (author)

Combined soil washing and CDEO for the removal of atrazine from soils

Energy Technology Data Exchange (ETDEWEB)

Vieira dos Santos, Elisama [Institute of Chemistry, Federal University of Rio Grande do Norte, Lagoa Nova CEP 59078-970, Natal, RN (Brazil); Sáez, Cristina [Department of Chemical Engineering, Universidad de Castilla – La Mancha, Enrique Costa Building, Campus Universitario s/n, 13071 Ciudad Real (Spain); Martínez-Huitle, Carlos Alberto [Institute of Chemistry, Federal University of Rio Grande do Norte, Lagoa Nova CEP 59078-970, Natal, RN (Brazil); Cañizares, Pablo; Rodrigo, Manuel Andres [Department of Chemical Engineering, Universidad de Castilla – La Mancha, Enrique Costa Building, Campus Universitario s/n, 13071 Ciudad Real (Spain)

2015-12-30

Highlights: • Sequential soil washing-waste electrolysis is an efficient treatment for removing atrazine. • Ratio surfactant/soil influences on the size of micelles and organic load. • Electrolysis with diamond anodes oxidizes pollutants from soils washing wastes. • Electrolysis of soil washing fluids promotes the reduction in size of micelles. • Sulphate ions release from the oxidation of SDS participates in the oxidation process. - Abstract: In this work, it is studied the removal of atrazine from spiked soils by soil washing using surfactant fluids, followed by the treatment of the resulting washing waste by electrolysis with boron doped diamond (BDD) anode. Results confirm that combination of both technologies is efficient for the removal and total mineralization of atrazine. Ratio surfactant/soil is a key parameter for the removal of atrazine from soil and influences significantly in the characteristic of the wastewater produced, affecting not only to the total organic load but also to the mean size of micelles. The higher the ratio surfactant soil, the lower is the size of the particles. Electrolyses of this type of waste attain the complete mineralization. TOC and COD are removed from the start of the treatment but the key of the treatment is the reduction in size of the micelles, which lead to a higher negative charge in the surface and to the faster depletion of the surfactant as compared with the pesticide.

Development of a bacterial bioassay for atrazine and cyanuric acid detection

Directory of Open Access Journals (Sweden)

Anna eHUA

2015-03-01

Full Text Available The s-triazine herbicides are compounds which can disseminate into soils and water. Due to their toxic effects on living organisms, their concentrations in drinking water are legislated by WHO recommendations. Here we have developed for the first time, to the best of our knowledge, an alternative method for physicochemical quantification using two bioluminescent bacterial biosensors: E. coli SM003 for cyanuric acid detection and E. coli SM004 for both atrazine and cyanuric acid detection. The concentration of cyanuric acid detection for E. coli SM003 ranges from 7.83 µM to 2.89 mM, and for E. coli SM004 ranges from 0.22 µM to 15 µM. Moreover, atrazine detection by E. coli SM004 ranges from 1.08 µM to 15 µM. According to WHO recommendations, the cyanuric acid detection range is sensitive enough to discriminate between polluted and drinking water. Nevertheless, the detection of atrazine by E. coli SM004 is only applicable for high concentrations of contaminants.

Involvement of ERK1/2 signaling pathway in atrazine action on FSH-stimulated LHR and CYP19A1 expression in rat granulosa cells

International Nuclear Information System (INIS)

Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana; Glisic, Branka; Kaisarevic, Sonja; Kovacevic, Radmila; Andric, Nebojsa

2013-01-01

Worldwide used herbicide atrazine is linked to reproductive dysfunction in females. In this study, we investigated the effects and the mechanism of atrazine action in the ovary using a primary culture of immature granulosa cells. In granulosa cells, follicle-stimulating hormone (FSH) activates both cyclic adenosine monophosphate (cAMP) and extracellular-regulated kinase 1/2 (ERK1/2) cascades, with cAMP pathway being more important for luteinizing hormone receptor (LHR) and aromatase (CYP19A1) mRNA expression. We report that 48 h after atrazine exposure the FSH-stimulated LHR and CYP19A1 mRNA expression and estradiol synthesis were decreased, with LHR mRNA being more sensitive to atrazine than CYP19A1 mRNA. Inadequate acquisition of LHR in the FSH-stimulated and atrazine-exposed granulosa cells renders human chorionic gonadotropin (hCG) ineffective to stimulate amphiregulin (Areg), epiregulin (Ereg), and progesterone receptor (Pgr) mRNA expression, suggesting anti-ovulatory effect of atrazine. To dissect the signaling cascade involved in atrazine action in granulosa cells, we used U0126, a pharmacological inhibitor of ERK1/2. U0126 prevents atrazine-induced decrease in LHR and CYP19A1 mRNA levels and estradiol production in the FSH-stimulated granulosa cells. ERK1/2 inactivation restores the ability of hCG to induce expression of the ovulatory genes in atrazine-exposed granulosa cells. Cell-based ELISA assay revealed that atrazine does not change the FSH-stimulated ERK1/2 phosphorylation in granulosa cells. The results from this study reveal that atrazine does not affect but requires ERK1/2 phosphorylation to cause decrease in the FSH-induced LHR and CYP19A1 mRNA levels and estradiol production in immature granulosa cells, thus compromising ovulation and female fertility. - Highlights: • Atrazine inhibits estradiol production in FSH-stimulated granulosa cells. • Atrazine inhibits LHR and Cyp19a1 mRNA expression in FSH-stimulated granulosa cells. • Atrazine

Involvement of ERK1/2 signaling pathway in atrazine action on FSH-stimulated LHR and CYP19A1 expression in rat granulosa cells

Energy Technology Data Exchange (ETDEWEB)

Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana; Glisic, Branka; Kaisarevic, Sonja; Kovacevic, Radmila; Andric, Nebojsa, E-mail: nebojsa.andric@dbe.uns.ac.rs

2013-07-01

Worldwide used herbicide atrazine is linked to reproductive dysfunction in females. In this study, we investigated the effects and the mechanism of atrazine action in the ovary using a primary culture of immature granulosa cells. In granulosa cells, follicle-stimulating hormone (FSH) activates both cyclic adenosine monophosphate (cAMP) and extracellular-regulated kinase 1/2 (ERK1/2) cascades, with cAMP pathway being more important for luteinizing hormone receptor (LHR) and aromatase (CYP19A1) mRNA expression. We report that 48 h after atrazine exposure the FSH-stimulated LHR and CYP19A1 mRNA expression and estradiol synthesis were decreased, with LHR mRNA being more sensitive to atrazine than CYP19A1 mRNA. Inadequate acquisition of LHR in the FSH-stimulated and atrazine-exposed granulosa cells renders human chorionic gonadotropin (hCG) ineffective to stimulate amphiregulin (Areg), epiregulin (Ereg), and progesterone receptor (Pgr) mRNA expression, suggesting anti-ovulatory effect of atrazine. To dissect the signaling cascade involved in atrazine action in granulosa cells, we used U0126, a pharmacological inhibitor of ERK1/2. U0126 prevents atrazine-induced decrease in LHR and CYP19A1 mRNA levels and estradiol production in the FSH-stimulated granulosa cells. ERK1/2 inactivation restores the ability of hCG to induce expression of the ovulatory genes in atrazine-exposed granulosa cells. Cell-based ELISA assay revealed that atrazine does not change the FSH-stimulated ERK1/2 phosphorylation in granulosa cells. The results from this study reveal that atrazine does not affect but requires ERK1/2 phosphorylation to cause decrease in the FSH-induced LHR and CYP19A1 mRNA levels and estradiol production in immature granulosa cells, thus compromising ovulation and female fertility. - Highlights: • Atrazine inhibits estradiol production in FSH-stimulated granulosa cells. • Atrazine inhibits LHR and Cyp19a1 mRNA expression in FSH-stimulated granulosa cells. • Atrazine

GESTATIONAL ATRAZINE EXPOSURE IN THE RAT: EFFECTS ON MAMMARY GLAND DEVELOPMENT AND FUNCTION IN MULTIPLE GENERATIONS

Science.gov (United States)

The chlorotriazine herbicides currently represent the most heavily used of all agricultural pesticides, with atrazine being the most common of these chemicals. Rodent toxicology studies indicate that atrazine can disrupt endocrine function and among its effects is an increased in...

Assessment of Atrazine contamination in water and soil in Ghana: A preliminary study in the Yilo Krobo and Mfantsiman Districts

International Nuclear Information System (INIS)

Darku, E. K.

2013-07-01

The thesis presents a study to determine the levels of atrazine in water and soil samples in selected farming communities in the Central and Eastern regions of Ghana, and provide baseline information on the contamination levels using high performance liquid chromatography (HPLC). Instrumental Nuclear Activation Analysis (INAA) was used for the determination of concentration of chlorine residue in all the atrazine extracts. Twenty-four (24) water samples, comprising twelve (12) each from Obawale and Bafikrom farming communities and their environs in the Eastern and Central Regions respectively and sixteen (16) soil samples from farms in the same location. Solid-phase extraction C 18 Sep-Pak cartridges were used for the isolation of atrazine residues from water samples in this investigation. Methanol (HPLC grade) was used to elute the atrazine, concentrated and transferred into vials for the determination of the atrazine contents. The same procedure was used for the determination of atrazine in soil samples using acetonitrile for the extraction. Residue of atrazine was detected in all water samples from Obawale with concentration ranging from 0.012 to 0.042µg/L with a mean concentration of 0.026µg/L whilst that of Baifikrom ranged from 0.01 to 0.04µg/L with a mean value of 0.007µg/L. Residue of atrazine was detected in ground water samples from Obawale with concentration ranging from 0.030µg/L to 0.930µg/L and from 0.038µg/L to 0.116µg/L at Bafikrom. The relative higher concentration of atrazine in the ground water sample was ro be expected since atrazine tend to be more stable in ground water. For soil samples, 8 out of the 16 samples recorded atrazine residue. For Obawale and Baifikrom, residues were detected in 5 and 3 samples ranging from 0.011µg/L to 0.041µg/L and 0.001µg/L to 0.009µg/L respectively. Using the INAA, concentration of chlorine residue was detected in all the atrazine extracts. The chlorine values ranged from 0.004µg/L to 0.01µg/L. In

SORPTION OF VINCLOZOLIN AND ATRAZINE ON FOUR GEOSORBENTS

Science.gov (United States)

The objectives of this study were to evaluate the magnitude and kinetics of vinclozolin and atrazine sorption on one surface soil and three freshwater sediments using batch and column techniques. Data from miscible displacement column studies were analyzed using a two-domain, fir...

The possible role of hydroxylation in the detoxification of atrazine in mature vetiver (Chrysopogon zizanioides Nash) grown in hydroponics.

Science.gov (United States)

Marcacci, Sylvie; Raventon, Muriel; Ravanel, Patrick; Schwitzguébel, Jean-Paul

2005-01-01

The resistance mechanism of vetiver (Chrysopogon zizanioides) to atrazine was investigated to evaluate its potential for phytoremediation of environment contaminated with the herbicide. Plants known to metabolise atrazine rely on hydroxylation mediated by benzoxazinones, conjugation catalyzed by glutathione-S-transferases and dealkylation probably mediated by cytochromes P450. All three possibilities were explored in mature vetiver grown in hydroponics during this research project. Here we report on the chemical role of benzoxazinones in the transformation of atrazine. Fresh vetiver roots and leaves were cut to extract and study their content in benzoxazinones known to hydroxylate atrazine, such as 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA), 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) and their mono- and di-glucosylated forms. Identification of benzoxazinones was performed by thin layer chromatography (TLC) and comparison of retention factors (Rf) and UV spectra with standards: although some products exhibited the same Rf as standards, UV spectra were different. Furthermore, in vitro hydroxylation of atrazine could not be detected in the presence of vetiver extracts. Finally, vetiver organs exposed to [14C]-atrazine did not produce any significant amount of hydroxylated products, such as hydroxyatrazine (HATR), hydroxy-deethylatrazine (HDEA), and hydroxy-deisopropylatrazine (HDIA). Altogether, these metabolic features suggest that hydroxylation was not a major metabolic pathway of atrazine in vetiver.

Modelling of degradation processes in creep resistant steels through accelerated creep tests after long-term isothermal ageing

Energy Technology Data Exchange (ETDEWEB)

Sklenicka, V.; Kucharova, K.; Svoboda, M.; Kroupa, A.; Kloc, L. [Academy of Sciences of the Czech Republic, Brno (Czech Republic). Inst. of Physics of Materials; Cmakal, J. [UJP PRAHA a.s., Praha-Zbraslav (Czech Republic)

2010-07-01

Creep behaviour and degradation of creep properties of creep resistant materials are phenomena of major practical relevance, often limiting the lives of components and structures designed to operate for long periods under stress at elevated and/or high temperatures. Since life expectancy is, in reality, based on the ability of the material to retain its high-temperature creep strength for the projected designed life, methods of creep properties assessment based on microstructural evolution in the material during creep rather than simple parametric extrapolation of short-term creep tests are necessary. In this paper we will try to further clarify the creep-strength degradation of selected advanced creep resistant steels. In order to accelerate some microstructural changes and thus to simulate degradation processes in long-term service, isothermal ageing at 650 C for 10 000 h was applied to P91 and P23 steels in their as-received states. The accelerated tensile creep tests were performed at temperature 600 C in argon atmosphere on all steels both in the as-received state and after long-term isothermal ageing, in an effort to obtain a more complete description of the role of microstructural stability in high temperature creep of these steels. Creep tests were followed by microstructural investigations by means of both transmission and scanning electron microscopy and by the thermodynamic calculations. The applicability of the accelerated creep tests was verified by the theoretical modelling of the phase equilibria at different temperatures. It is suggested that under restructed oxidation due to argon atmosphere microstructural instability is the main detrimental process in the long-term degradation of the creep rupture strength of these steels. (orig.)

Atrazine alters expression of reproductive and stress genes in the developing hypothalamus of the snapping turtle, Chelydra serpentina.

Science.gov (United States)

Russart, Kathryn L G; Rhen, Turk

2016-07-29

Atrazine is an herbicide used to control broadleaf grasses and a suspected endocrine disrupting chemical. Snapping turtles lay eggs between late May and early June, which could lead to atrazine exposure via field runoff. Our goal was to determine whether a single exposure to 2ppb or 40ppb atrazine during embryogenesis could induce short- and long-term changes in gene expression within the hypothalamus of snapping turtles. We treated eggs with atrazine following sex determination and measured gene expression within the hypothalamus. We selected genes a priori for their role in the hypothalamus-pituitary-gonad or the hypothalamus-pituitary-adrenal axes of the endocrine system. We did not identify any changes in gene expression 24-h after treatment. However, at hatching AR, Kiss1R, and POMC expression was upregulated in both sexes, while expression of CYP19A1 and PDYN was increased in females. Six months after hatching, CYP19A1 and PRLH expression was increased in animals treated with 2ppb atrazine. Our study shows persistent changes in hypothalamic gene expression due to low-dose embryonic exposure to the herbicide atrazine with significant effects in both the HPG and HPA axes. Effects reported here appear to be conserved among vertebrates. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Results of metallographical diagnostic examination of Navy half-watt thermoelectric converters degraded by accelerated tests

International Nuclear Information System (INIS)

Rosell, F.E. Jr.; Rouklove, P.G.

1977-01-01

To verify the 15-year reliability of the Navy half-watt radioisotope thermoelectric generator (RTG), bismuth--telluride thermoelectric converters were submitted to testing at high temperatures which accelerated the degradation and caused failure of the converters. Metallographic diagnostic examination of failed units verified failure mechanisms. Results of diagnostic examinations are presented

Degradation mechanisms and accelerated testing in PEM fuel cells

Energy Technology Data Exchange (ETDEWEB)

Borup, Rodney L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory

2010-01-01

The durability of PEM fuel cells is a major barrier to the commercialization of these systems for stationary and transportation power applications. Although there has been recent progress in improving durability, further improvements are needed to meet the commercialization targets. Past improvements have largely been made possible because of the fundamental understanding of the underlying degradation mechanisms. By investigating component and cell degradation modes; defining the fundamental degradation mechanisms of components and component interactions new materials can be designed to improve durability. Various factors have been shown to affect the useful life of PEM fuel cells. Other issues arise from component optimization. Operational conditions (such as impurities in either the fuel and oxidant stream), cell environment, temperature (including subfreezing exposure), pressure, current, voltage, etc.; or transient versus continuous operation, including start-up and shutdown procedures, represent other factors that can affect cell performance and durability. The need for Accelerated Stress Tests (ASTs) can be quickly understood given the target lives for fuel cell systems: 5000 hours ({approx} 7 months) for automotive, and 40,000 hrs ({approx} 4.6 years) for stationary systems. Thus testing methods that enable more rapid screening of individual components to determine their durability characteristics, such as off-line environmental testing, are needed for evaluating new component durability in a reasonable turn-around time. This allows proposed improvements in a component to be evaluated rapidly and independently, subsequently allowing rapid advancement in PEM fuel cell durability. These tests are also crucial to developers in order to make sure that they do not sacrifice durability while making improvements in costs (e.g. lower platinum group metal [PGM] loading) and performance (e.g. thinner membrane or a GDL with better water management properties). To

Coating and Interface Degradation of Coated steel, Part 2: Accelerated Laboratory Tests

International Nuclear Information System (INIS)

Cambier, S.M.; Frankel, G.S.

2014-01-01

In a previous paper, it was demonstrated that the measurement of cathodic delamination by the Scanning Kelvin Probe can assess the interface stability of poly(vinyl butyral) (PVB) coated steel after field exposure. This technique was utilized to characterize the degradation of the polymer/metal interface in several outdoor climates. In this paper, the effects of environmental factors on the interface degradation were investigated in the laboratory. The mechanisms measured in the field were reproduced to provide input in the development of an appropriate accelerated test for PVB coated steel. The ASTM B117 and G154 standardized tests were investigated individually and sequentially. The interface stability improved after 24 h of ASTM G154 exposure. After 144 h of exposure to ASTM G154 exposure, polymer oxidation took place simultaneously with interface degradation. The condensation phase of the ASTM G154 test was responsible for the interface improvement while the ultraviolet radiation triggered the interface degradation. Pre-exposure to ASTM G154 delayed wet de-adhesion during ASTM B117 exposure. After wet de-adhesion caused by 6 h of ASTM B117, exposure to ASTM G154 for 24 h increased the interface stability. The effects of ultraviolet radiation, relative humidity, temperature and environment on interface degradation were investigated in a special chamber. Humidity was the primary factor found to influence the interface improvement during G154 exposure. A wet/dry salt fog cycle with irradiation by an ultraviolet or filtered xenon arc lamp around room temperature was suggested to reproduce the competition between the interface improvement and the interface degradation that takes place in the field

Atividade de glutationa S-transferase na metabolização de acetochlor, atrazine e oxyfluorfen em milho (Zea mays L., sorgo (Sorghum bicolor L. e trigo (Triticum aestivum L. (Poaceae Glutathione S-transferase activity in acetochlor, atrazine and oxyfluorfen metabolization in maize (Zea mays L., sorghum (Sorghum bicolor L. and wheat (Triticum aestivumL. (Poaceae

Directory of Open Access Journals (Sweden)

Ethel Lourenzi Barbosa Novelli

2002-05-01

Full Text Available Este experimento foi conduzido para avaliar a seletividade em plantas dos herbicidas acetochlor, atrazine e oxyfluorfen em relação à atividade da glutationa S-transferase (GST em plantas de milho (Zea mays L., sorgo (Sorghum bicolor L. e trigo (Triticum aestivum L. (Poaceae. A atividade da GST foi detectada às 24, 48 e 72 horas após as aplicaç��es dos tratamentos. Os tratamentos do experimento consistiram de aplicação com água (controle, acetochlor (3 L.ha-1, atrazine (4 L.ha-1 e oxyfluorfen (1 L.ha-1. As maiores atividades de GST foram observadas na presença de acetochlor, principalmente às 48 horas após o tratamento. Esses aumentos foram 105, 148 e 118% em relação ao controle para milho, sorgo e trigo, respectivamente. É sugerido que a GST pode ter papel na degradação de acetochlor e pode ser uma das razões para a seletividade desse herbicida para essas culturas.This experiment was conducted to evaluate the acetochlor, atrazine and oxyfluorfen herbicides plant selectivity, in relation to glutathione S-transferase activity (GST in maize (Zea mays L., sorghum (Sorghum bicolor L. and wheat (Triticum aestivum L (Poaceae plants. GST activity was detected 24, 48 and 72 hours after treatment applications. The experiment's treatments consisted of spraying plants with water (control, acetochlor (3 L.ha-1`, atrazine (4 L.ha-1 and oxyfluorfen (1 L.ha-1. The highest GST activities were observed in presence of acetochlor, mainly at 48 hours after treatment. These increments were 105, 148 and 118% when compared to maize, sorghum and wheat control groups, respectively. It is suggested that the GST may have a role in acetochlor degradation and it may be a reason for this herbicide's selectivity in these crops.

Atrazine sorption by hydroxy-interlayered clays and their organic complexes.

Science.gov (United States)

Indraratne, Srimathie P; Farenhorst, Annemieke; Goh, Tee Boon

2008-01-01

This study examined the sorption of atrazine by hydroxy-Fe interlayered montmorillonite (FeMt) and its hydroquinone (FeMtHQ), citrate (FeMtCt) and catechol (FeMtCC) complexes as well as by hydroxy-Al interlayered montmorillonite (AlMt) and its hydroquinone (AlMtHQ) and citrate (AlMtCt) complexes. Found among the clays were sorption distribution coefficients (K(d)) ranging from 24 to 123 mL g(-1) and maximum sorption (M) ranging from 2.2 to 16.8 microg g(-1). Both K(d) and M decreased in the order of FeMtCC > FeMtHQ > AlMtHQ > (AlMt = FeMt) > (AlMtCt = FeMtCt). The pH was negatively correlated with both K(d) (r = -0.90, p 0.96, p 0.94, p AlMt). This suggests that functional groups of Fe-OH and Al-OH in FeMt and AlMt reduced the available sorption sites for atrazine by making complexes with citrate ions while forming FeMtCt and AlMtCt. The atrazine was sorbed through the hydrophobic interactions with organic compound surfaces as well as through H-bonding and ionic bonding with clay-mineral surfaces.

Biochar-supported reduced graphene oxide composite for adsorption and coadsorption of atrazine and lead ions

Science.gov (United States)

Zhang, Ying; Cao, Bo; Zhao, Lulu; Sun, Lili; Gao, Yan; Li, Jiaojiao; Yang, Fan

2018-01-01

To explore potential in application for simultaneous removal of atrazine and lead ions (Pd2+), the adsorption and coadsorption of atrazine and Pd2+ is evaluated onto a novel biochar-supported reduced graphene oxide composite (RGO-BC), which has been successfully developed via slow pyrolysis of graphene oxide (GO) pretreated corn straws. Structure and morphology analysis reveal that GO nanosheets are coated on the surface of biochar (BC) mainly through π-π interactions, notably, GO nanosheets after annealing reduction can basically retain the original morphology, meanwhile, the change of physico-chemical properties on the surface endow excellent adsorption capaities of 26.10 mg g-1 for Pb2+ and 67.55 mg g-1 for atrazine. A significant difference is in sorption of Pb2+ and atrazine on RGO-BC sample in both single- and binary-solute systems. The adsorption capacity of RGO-BC still remained above 54.58 mg g-1 after four times regeneration (81% adsorption capacity remained), demonstrating a promising candidate for the application of removal contaminant in the environment.

Effects of endosulfan, thiamethoxam, and indoxacarb in combination with atrazine on multi-biomarkers in Gammarus kischineffensis.

Science.gov (United States)

Demirci, Özlem; Güven, Kemal; Asma, Dilek; Öğüt, Serdal; Uğurlu, Pelin

2018-01-01

Studies addressing the toxicity of pesticides towards non-target organisms focus on the median lethal concentration and biochemical response of individual pesticides. However, when determining environmental risks, it is important to test the combined effects of pesticides, such as insecticides and herbicides, which are frequently used together in agricultural areas. Here we aimed to investigate the toxic effects of the combined use of the herbicide atrazine and the insecticides, endosulfan, indoxacarb, and thiamethoxam on Gammarus kischineffensis. To do this, we tested the activities of oxidative stress, detoxification, and neurotoxicity biomarkers. Compared to atrazine alone, we detected higher glutathione-S-transferase, catalase and superoxide dismutase activities (oxidative stress biomarkers) when atrazine was combined with either endosulfan or indoxacarb. However, higher IBR values were determined in organisms where pesticide mixtures were used according to individual use. Based on these results, mixtures of atrazine and other pesticides may cause synergistic effects and may be evidence of increased toxicity and oxidative stress. Copyright © 2017 Elsevier Inc. All rights reserved.

Development and Application of Watershed Regressions for Pesticides (WARP) for Estimating Atrazine Concentration Distributions in Streams

Science.gov (United States)

Larson, Steven J.; Crawford, Charles G.; Gilliom, Robert J.

2004-01-01

Regression models were developed for predicting atrazine concentration distributions in rivers and streams, using the Watershed Regressions for Pesticides (WARP) methodology. Separate regression equations were derived for each of nine percentiles of the annual distribution of atrazine concentrations and for the annual time-weighted mean atrazine concentration. In addition, seasonal models were developed for two specific periods of the year--the high season, when the highest atrazine concentrations are expected in streams, and the low season, when concentrations are expected to be low or undetectable. Various nationally available watershed parameters were used as explanatory variables, including atrazine use intensity, soil characteristics, hydrologic parameters, climate and weather variables, land use, and agricultural management practices. Concentration data from 112 river and stream stations sampled as part of the U.S. Geological Survey's National Water-Quality Assessment and National Stream Quality Accounting Network Programs were used for computing the concentration percentiles and mean concentrations used as the response variables in regression models. Tobit regression methods, using maximum likelihood estimation, were used for developing the models because some of the concentration values used for the response variables were censored (reported as less than a detection threshold). Data from 26 stations not used for model development were used for model validation. The annual models accounted for 62 to 77 percent of the variability in concentrations among the 112 model development stations. Atrazine use intensity (the amount of atrazine used in the watershed divided by watershed area) was the most important explanatory variable in all models, but additional watershed parameters significantly increased the amount of variability explained by the models. Predicted concentrations from all 10 models were within a factor of 10 of the observed concentrations at most

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, which are the two main environmental stress factors that promote potential-induced degradation (PID). This model was derived...

Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

DEFF Research Database (Denmark)

Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

2015-01-01

An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, the two main environmental stress factors that promote potential-induced degradation. This model was derived from module pow...

Impact of long-term wastewater irrigation on sorption and transport of atrazine in Mexican agricultural soils.

Science.gov (United States)

Müller, K; Duwig, C; Prado, B; Siebe, C; Hidalgo, C; Etchevers, J

2012-01-01

In the Mezquital Valley, Mexico, crops have been irrigated with untreated municipal wastewater for more than a century. Atrazine has been applied to maize and alfalfa grown in the area for weed control for 15 years. Our objectives were to analyse (i) how wastewater irrigation affects the filtering of atrazine, and (ii) if the length of irrigation has a significant impact. We compared atrazine sorption to Phaeozems that have been irrigated with raw wastewater for 35 (P35) and 85 (P85) years with sorption to a non-irrigated (P0) Phaeozem soil under rainfed agriculture. The use of bromide as an inert water tracer in column experiments and the subsequent analysis of the tracers' breakthrough curves allowed the calibration of the hydrodynamic parameters of a two-site non equilibrium convection-dispersion model. The quality of the irrigation water significantly altered the soils' hydrodynamic properties (hydraulic conductivity, dispersivity and the size of pores that are hydraulically active). The impacts on soil chemical properties (total organic carbon content and pH) were not significant, while the sodium adsorption ratio was significantly increased. Sorption and desorption isotherms, determined in batch and column experiments, showed enhanced atrazine sorption and reduced and slower desorption in wastewater-irrigated soils. These effects increased with the length of irrigation. The intensified sorption-desorption hysteresis in wastewater-irrigated soils indicated that the soil organic matter developed in these soils had fewer high-energy, easily accessible sorption sites available, leading to lower and slower atrazine desorption rates. This study leads to the conclusion that wastewater irrigation decreases atrazine mobility in the Mezquital valley Phaeozems by decreasing the hydraulic conductivity and increasing the soil's sorption capacity.

Reliability demonstration methodology for products with Gamma Process by optimal accelerated degradation testing

International Nuclear Information System (INIS)

Zhang, Chunhua; Lu, Xiang; Tan, Yuanyuan; Wang, Yashun

2015-01-01

For products with high reliability and long lifetime, accelerated degradation testing (ADT) may be adopted during product development phase to verify whether its reliability satisfies the predetermined level within feasible test duration. The actual degradation from engineering is usually a strictly monotonic process, such as fatigue crack growth, wear, and erosion. However, the method for reliability demonstration by ADT with monotonic degradation process has not been investigated so far. This paper proposes a reliability demonstration methodology by ADT for this kind of product. We first apply Gamma process to describe the monotonic degradation. Next, we present a reliability demonstration method by converting the required reliability level into allowable cumulative degradation in ADT and comparing the actual accumulative degradation with the allowable level. Further, we suggest an analytical optimal ADT design method for more efficient reliability demonstration by minimizing the asymptotic variance of decision variable in reliability demonstration under the constraints of sample size, test duration, test cost, and predetermined decision risks. The method is validated and illustrated with example on reliability demonstration of alloy product, and is applied to demonstrate the wear reliability within long service duration of spherical plain bearing in the end. - Highlights: • We present a reliability demonstration method by ADT for products with monotonic degradation process, which may be applied to verify reliability with long service life for products with monotonic degradation process within feasible test duration. • We suggest an analytical optimal ADT design method for more efficient reliability demonstration, which differs from the existed optimal ADT design for more accurate reliability estimation by different objective function and different constraints. • The methods are applied to demonstrate the wear reliability within long service duration of

Spatial and temporal variation of algal assemblages in six Midwest agricultural streams having varying levels of atrazine and other physicochemical attributes

Energy Technology Data Exchange (ETDEWEB)

Andrus, J. Malia, E-mail: andrusm@waterborne-env.com [Waterborne Environmental, Inc., 2001 South First Street, Suite 109, Champaign, IL 61820 (United States); Winter, Diane, E-mail: dwinter1@juno.com [Rhithron Associates, Inc., 33 Fort Missoula Rd., Missoula, MT 59804 (United States); Algal Analysis, LLC, Missoula, MT (United States); Scanlan, Michael, E-mail: mscanlan@maptech-inc.com [MapTech, Inc., 3154 State Street, Blacksburg, VA 24060 (United States); Sullivan, Sean, E-mail: ssullivan@rhithron.com [Rhithron Associates, Inc., 33 Fort Missoula Rd., Missoula, MT 59804 (United States); Bollman, Wease, E-mail: wbollman@rhithron.com [Rhithron Associates, Inc., 33 Fort Missoula Rd., Missoula, MT 59804 (United States); Waggoner, J.B., E-mail: jwaggoner@inovatia.com [Inovatia, Inc., 120 East Davis Street, Fayette, MO 65248 (United States); Hosmer, Alan J., E-mail: alan.hosmer@syngenta.com [Syngenta Crop Protection, LLC, 410 Swing Rd., Greensboro, NC 27419 (United States); Brain, Richard A., E-mail: richard.brain@syngenta.com [Syngenta Crop Protection, LLC, 410 Swing Rd., Greensboro, NC 27419 (United States)

2015-02-01

Potential effects of pesticides on stream algae occur alongside complex environmental influences; in situ studies examining these effects together are few, and have not typically controlled for collinearity of variables. We monitored the dynamics of periphyton, phytoplankton, and environmental factors including atrazine, and other water chemistry variables at 6 agricultural streams in the Midwest US from spring to summer of 2011 and 2012, and used variation partitioning of community models to determine the community inertia that is explained uniquely and/or jointly by atrazine and other environmental factors or groups of factors. Periphyton and phytoplankton assemblages were significantly structured by year, day of year, and site, and exhibited dynamic synchrony both between site–years and between periphyton and phytoplankton in the same site–year. The majority of inertia in the models (55.4% for periphyton, 68.4% for phytoplankton) was unexplained. The explained inertia in the models was predominantly shared (confounded) between variables and variable groups (13.3, 30.9%); the magnitude of inertia that was explained uniquely by variable groups (15.1, 18.3%) was of the order hydroclimate > chemistry > geography > atrazine for periphyton, and chemistry > hydroclimate > geography > atrazine for phytoplankton. The variables most influential to the assemblage structure included flow and velocity variables, and time since pulses above certain thresholds of nitrate + nitrite, total phosphorus, total suspended solids, and atrazine. Time since a ≥ 30 μg/L atrazine pulse uniquely explained more inertia than time since pulses ≥ 10 μg/L or daily or historic atrazine concentrations; this result is consistent with studies concluding that the effects of atrazine on algae typically only occur at ≥ 30 μg/L and are recovered from. - Highlights: • We monitored algal communities at 6 Midwest streams receiving atrazine in 2011 and 2012. • Partitioning of CCA models of

Spatial and temporal variation of algal assemblages in six Midwest agricultural streams having varying levels of atrazine and other physicochemical attributes

International Nuclear Information System (INIS)

Andrus, J. Malia; Winter, Diane; Scanlan, Michael; Sullivan, Sean; Bollman, Wease; Waggoner, J.B.; Hosmer, Alan J.; Brain, Richard A.

2015-01-01

Potential effects of pesticides on stream algae occur alongside complex environmental influences; in situ studies examining these effects together are few, and have not typically controlled for collinearity of variables. We monitored the dynamics of periphyton, phytoplankton, and environmental factors including atrazine, and other water chemistry variables at 6 agricultural streams in the Midwest US from spring to summer of 2011 and 2012, and used variation partitioning of community models to determine the community inertia that is explained uniquely and/or jointly by atrazine and other environmental factors or groups of factors. Periphyton and phytoplankton assemblages were significantly structured by year, day of year, and site, and exhibited dynamic synchrony both between site–years and between periphyton and phytoplankton in the same site–year. The majority of inertia in the models (55.4% for periphyton, 68.4% for phytoplankton) was unexplained. The explained inertia in the models was predominantly shared (confounded) between variables and variable groups (13.3, 30.9%); the magnitude of inertia that was explained uniquely by variable groups (15.1, 18.3%) was of the order hydroclimate > chemistry > geography > atrazine for periphyton, and chemistry > hydroclimate > geography > atrazine for phytoplankton. The variables most influential to the assemblage structure included flow and velocity variables, and time since pulses above certain thresholds of nitrate + nitrite, total phosphorus, total suspended solids, and atrazine. Time since a ≥ 30 μg/L atrazine pulse uniquely explained more inertia than time since pulses ≥ 10 μg/L or daily or historic atrazine concentrations; this result is consistent with studies concluding that the effects of atrazine on algae typically only occur at ≥ 30 μg/L and are recovered from. - Highlights: • We monitored algal communities at 6 Midwest streams receiving atrazine in 2011 and 2012. • Partitioning of CCA models of

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions

Science.gov (United States)

Sun, Bo; Ye, Tianyuan; Feng, Qiang; Yao, Jinghua; Wei, Mumeng

2015-01-01

This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu2O film increased gradually. Its corrosion product was Cu2(OH)3Cl, which increased in quantity over time. Cl− was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss), degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e., dissolved oxygen (DO) and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet. PMID:28793549

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions.

Science.gov (United States)

Sun, Bo; Ye, Tianyuan; Feng, Qiang; Yao, Jinghua; Wei, Mumeng

2015-09-10

This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu₂O film increased gradually. Its corrosion product was Cu₂(OH)₃Cl, which increased in quantity over time. Cl - was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss), degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e. , dissolved oxygen (DO) and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet.

Accelerated Degradation Test and Predictive Failure Analysis of B10 Copper-Nickel Alloy under Marine Environmental Conditions

Directory of Open Access Journals (Sweden)

Bo Sun

2015-09-01

Full Text Available This paper studies the corrosion behavior of B10 copper-nickel alloy in marine environment. Accelerated degradation test under marine environmental conditions was designed and performed based on the accelerated testing principle and the corrosion degradation mechanism. With the prolongation of marine corrosion time, the thickness of Cu2O film increased gradually. Its corrosion product was Cu2(OH3Cl, which increased in quantity over time. Cl− was the major factor responsible for the marine corrosion of copper and copper alloy. Through the nonlinear fitting of corrosion rate and corrosion quantity (corrosion weight loss, degradation data of different corrosion cycles, the quantitative effects of two major factors, i.e., dissolved oxygen (DO and corrosion medium temperature, on corrosion behavior of copper alloy were analyzed. The corrosion failure prediction models under different ambient conditions were built. One-day corrosion weight loss under oxygenated stirring conditions was equivalent to 1.31-day weight loss under stationary conditions, and the corrosion rate under oxygenated conditions was 1.31 times higher than that under stationary conditions. In addition, corrosion medium temperature had a significant effect on the corrosion of B10 copper sheet.

Agro-waste biosorbents: Effect of physico-chemical properties on atrazine and imidacloprid sorption.

Science.gov (United States)

Mandal, Abhishek; Singh, Neera; Nain, Lata

2017-09-02

Low cost agro-waste biosorbents namely eucalyptus bark (EB), corn cob (CC), bamboo chips (BC), rice straw (RS) and rice husk (RH) were characterized and used to study atrazine and imidacloprid sorption. Adsorption studies suggested that biosorbents greatly varied in their pesticide sorption behaviour. The EB was the best biosorbent to sorb both atrazine and imidacloprid with K F values of 169.9 and 85.71, respectively. The adsorption isotherm were nonlinear in nature with slope (1/n) values imidacloprid sorption parameter [K F .(1/n)] with the physicochemical properties of the biosorbents suggested that atrazine adsorption correlated significantly to the aromaticity, polarity, surface area, fractal dimension, lacunarity and relative C-O band intensity parameters of biosorbents. Probably, both physisorption and electrostatic interactions were responsible for the pesticide sorption. The eucalyptus bark can be exploited as low cost adsorbent for the removal of these pesticides as well as a component of on-farm biopurification systems.

Effects of nitrate and atrazine on larval development and sexual differentiation in the northern leopard frog Rana pipiens.

Science.gov (United States)

Orton, Frances; Carr, James A; Handy, Richard D

2006-01-01

Pollution from agrochemicals may be contributing to the global decline in amphibian populations. Environmentally relevant concentrations of nitrate and/or atrazine on anuran development and gonadal differentiation were tested. Four replicates of 20 tadpoles per tank (80/treatment) were exposed from Taylor-Kollros stage 2 to 3 to stage 23 to 34 to either 10 mg/L nitrate, 10 microg/L atrazine, a combined exposure of 10 mg/L nitrate plus 10 microg/L atrazine, or untreated controls. No treatment-dependent effects on weight, snout-vent or hind limb length, or time to forelimb emergence were observed. The proportions of females increased in all treatments compared to the controls, especially in the combined treatment (chi2 = 17.90, df = 6, p = 0.0065, combined = 66.4% female, control = 41% female). The frequency of intersex was low in all treatments. No treatment-related effects on the total number of spermatogenic cells were observed, but the ratio of cell types differed in that testes from animals in the treated groups exhibited more spermatogonia, fewer spermatocytes, and more spermatids than the control (significantly different, Kruskal-Wallis, p < 0.05). Ovaries from animals treated with nitrate or atrazine exhibited larger immature (previtellogenic) and mature (vitellogenic) follicles, but ovaries from the combined treatment had larger immature follicles only. Testicular oocytes were observed in the nitrate-only and atrazine-only treatments, and the control treatment, but not the combined treatment. Overall, this study has demonstrated changes in sex ratios that are more marked in response to combined nitrate/atrazine exposure than with these chemicals alone. Histological evidence suggests that premature maturation of gonad may occur as a result of nitrate and/or atrazine exposure during larval development.

Determination of Impurities of Atrazine by HPLP-MS

Energy Technology Data Exchange (ETDEWEB)

Canping, Pan [Department of Applied Chemistry, China Agricultural University Beijing (China)

2009-07-15

The determination of the main impurities of the herbicide atrazine by GC/FID, GC/MS and LC/MS is described. The most relevant technical impurities were synthesized and characterized by IR and UV spectroscopy as well. The impurity profiles of different technical grade formulated products were tested and the typical impurities identified. (author)

Optimal Constant-Stress Accelerated Degradation Test Plans Using Nonlinear Generalized Wiener Process

Directory of Open Access Journals (Sweden)

Zhen Chen

2016-01-01

Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.

Optical characterization of voltage-accelerated degradation in CH3NH3PbI3 perovskite solar cells.

Science.gov (United States)

Handa, Taketo; Tex, David M; Shimazaki, Ai; Aharen, Tomoko; Wakamiya, Atsushi; Kanemitsu, Yoshihiko

2016-05-16

We investigate the performance degradation mechanism of CH3NH3PbI3 perovskite solar cells under bias voltage in air and nitrogen atmospheres using photoluminescence and electroluminescence techniques. When applying forward bias, the power conversion efficiency of the solar cells decreased significantly in air, but showed no degradation in nitrogen atmosphere. Time-resolved photoluminescence measurements on these devices revealed that the application of forward bias in air accelerates the generation of non-radiative recombination centers in the perovskite layer buried in the device. We found a negative correlation between the electroluminescence intensity and the injected current intensity in air. The irreversible change of the perovskite grain surface in air initiates the degradation of the perovskite solar cells.

Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data

Science.gov (United States)

Lai, T.; Biggie, R.; Brooks, A.; Potter, B. G.; Simmons-Potter, K.

2015-09-01

Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following

Influence of light intensity on the toxicity of atrazine to the submerged freshwater aquatic macrophyte Elodea canadensis.

Science.gov (United States)

Brain, Richard A; Hoberg, James; Hosmer, Alan J; Wall, Steven B

2012-05-01

Light intensity can have a profound influence on the degree of phytotoxicity experienced by plants exposed to photosystem II (PSII) inhibiting herbicides. This relationship was evaluated in the submerged aquatic macrophyte Elodea canadensis exposed to three different concentrations of atrazine (510, 1000 and 2000 μg a.i./L) plus an untreated control at three different light intensities (0, 500 and 6000 lx) under static-renewal conditions for 14 days. Under 500 lx light intensity, control plants demonstrated a rapid increase in shoot length but minimal increase in dry shoot weight, suggesting limited photosynthesis. Based on shoot-length and biomass, growth was not affected by any atrazine exposure relative to controls under dark conditions (0 lx). Under low-light conditions at 500 lx, exposures to 510, 1000 and 2000 μg a.i./L atrazine significantly decreased net shoot lengths by 34%, 38% and 35%, respectively, relative to corresponding (500 lx) controls. However, atrazine exposure under this light condition did not significantly decrease biomass (dry shoot weight). Compared to 6000 lx, only approximately 8% of photosynthetically active radiation (PAR) was measured under 500 lx intensity, indicating that minimal PAR was available for photosynthesis. Under optimal light conditions (6000 lx), net shoot lengths significantly decreased in the treated atrazine groups by 48%, 51% and 68%, and net dry shoot weights (biomass) were significantly decreased by 79%, 81% and 91%, respectively, relative to corresponding (6000 lx) controls. These data show that under low light conditions, atrazine-induced effects on dry shoot weight (biomass) are dependent on available PAR and active photosynthesis. Copyright © 2011 Elsevier Inc. All rights reserved.

Biomarker Analysis of American Toad (Anaxyrus Americanus) and Grey Tree Frog (Hyla Versicolor) Tadpoles Following Exposure to Atrazine

Science.gov (United States)

To better understand the mode of action of atrazine in amphibians, we utilized mass spectrometry-based metabolomics to investigate the biochemical changes in two species of larval amphibians exposed to atrazine. Our objectives were to 1) Use changes in endogenous metabolites to f...

Biomarker analysis of American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles following exposure to atrazine.

Science.gov (United States)

The objective of the current study was to use a biomarker-based approach to investigate the influence of atrazine exposure on American toad (Anaxyrus americanus) and grey tree frog (Hyla versicolor) tadpoles. Atrazine is one of the most frequently detected herbicides in environme...

Human health risk assessment of atrazine in water and soil in selected municipalities in Ashanti and Brong-Ahafo Region of Ghana

International Nuclear Information System (INIS)

Hope, F. A.

2013-06-01

Atrazine, one of the triazine herbicides, helps control the growth of weeds through inhibition of photosynthetic reactions. It is used extensively because it is economical and effective in reducing crop losses due to weed interference. It has gained much attention because of its frequent detection in surface and groundwater supplies. Even though most countries have banned the usage of atrazine due to health risk and associated environmental contamination, its is still used in Ghana. Knowledge of levels of Atrazine in the environment is essential for the protection of human health and the environment. The main objective of the study is to do a health risk assessment to show the implications of atrazine levels on human population. This is aimed at informing policy makers in pesticide management, especially Atrazine, and also to assist in protecting water resources. The study areas were maize farms in Dormaa, Sunyani and Nkoranza Districts all in the Brong Ahafo Regions as well as Offinso District in Ashanti Region, where a lot of atrazine has been used in maize production over the past ten years. Thirty-six water samples and twelve soil samples were collected in December 2011 from surface and groundwater distributed in the study areas. The herbicide was extracted from the samples using sonication and analyzed by High Performance Liquid Chromatography (HPLC). There were no detectable concentrations of Atrazine in some water bodies however others ranged from 0.004µg/L to 0.105µg/L. The highest mean value occurred at Dandwe River with mean concentration of 0.076±0.023µg/L. The streams have concentrations between 0.033µg/L and 0.111µg/L with an average of 0.071µg/L. Out of the three streams sampled. two streams showed the presence of Atrazine with averages of 0.089µg/L and 0.053µg/L. Most of the hand dug wells did not contain Atrazine above the limit of determination of 0.001µg/L. It was only in the Sunyani 1 area that the wells recorded an average of 0.004µg

Bioconcentration of atrazine and chlorophenols into roots and shoots of rice seedlings

International Nuclear Information System (INIS)

Su Yuhong; Zhu Yongguan

2006-01-01

Accumulation of o-chlorophenol (CP), 2,4-dichlorophenol (DCP), and atrazine (ATR), as single and mixed contaminants, from hydroponic solutions into roots and shoots of rice seedlings was studied following 48-h exposure of the plant roots. As single contaminants at low levels, the observed bioconcentration factors (BCFs) of CP and DCP with roots approximated the equilibrium values according to the partition-limited model. The BCF of atrazine with roots was about half the partition limit for unknown reasons. The BCFs of CP and ATR with shoots also approximated the partition limits, while the BCF for more lipophilic DCP with shoots was about half the estimated limit, due to insufficient water transport into plants for DCP. As mixed contaminants at low levels, the BCFs with both roots and shoots were comparable with those for the single contaminants; at high levels, the BCFs generally decreased because of the enhanced mixed-contaminant phytotoxicity, as manifested by the greatly reduced plant transpiration rate. - Uptakes of o-chlorophenol, 2,4-dichlorophenol, and atrazine at various levels from nutrient solution by roots and shoots of rice seedlings were investigated using a partition-limited model

Evaluation of potential mechanisms of atrazine-induced reproductive impairment in fathead minnow (Pimephales promelas) and Japanese medaka (Oryzias latipes)

Science.gov (United States)

Richter, Cathy; Papoulias, Diana M.; Whyte, Jeffrey J.; Tillitt, Donald E.

2016-01-01

Atrazine has been implicated in reproductive dysfunction of exposed organisms, and previous studies documented decreased egg production in Japanese medaka (Oryzias latipes) and fathead minnows (Pimephales promelas) during 30-d to 38-d exposures to 0.5 µg/L, 5 µg/L, and 50 µg/L atrazine. The authors evaluated possible mechanisms underlying the reduction in egg production. Gene expression in steroidogenesis pathways and the hypothalamus–pituitary–gonad axis of male and female fish was measured. Atrazine did not significantly induce gonad aromatase (cyp19a1a) expression. An atrazine-induced shift in the number of females in an active reproductive state was observed. Expression of the egg maturation genes vitellogenin 1 (vtg1) and zona pellucida glycoprotein 3.1 (zp3.1) in medaka females was correlated and had a bimodal distribution. In both species, females with low vtg1 or zp3.1 expression also had low expression of steroidogenesis genes in the gonad, estrogen receptor in the liver, and gonadotropins in the brain. In the medaka, the number of females per tank that had high expression of zp3.1 was significantly correlated with egg production per tank. The number of medaka females with low expression of zp3.1 increased significantly with atrazine exposure. Thus, the decline in egg production observed in response to atrazine exposure may be the result of a coordinated downregulation of genes required for reproduction in a subset of females.

In vitro degradation of the 32kDa PS II reaction centre protein

International Nuclear Information System (INIS)

Eckenswiller, L.C.; Greenberg, B.M.

1989-01-01

The 32kDa thylakoid membrane protein is an integral component of the PS II reaction centre. The protein, although stable in the dark, undergoes light dependent turnover. Light from the UV, visible and far-red spectral regions induce 32kDa protein degradation. To better understand 32kDa protein metabolism, an in vitro degradation system is being developed. It consists of isolated thylakoid membranes than contain radiolabelled protein. The 32kDa protein is actively and specifically degraded when the thylakoid preparation is exposed to UV or visible radiation. The protein is stable in the dark. The herbicides (atrazine and DCMU) inhibit degradation in the in vitro system as they do in vivo. Additionally, several methods of isolating thylakoids are being compared to optimize the 32kDa protein degradation reaction. The preparations will be evaluated based on their ability to permit light dependent degradation of the 32kDa protein without affecting the other membrane components

Ação dos herbicidas atrazine e glufosinate de amônio no aproveitamento de nitrogênio pelas plantas de milho Herbicides atrazine and ammonium glufosinate action on nitrogen usage by corn plants

Directory of Open Access Journals (Sweden)

N.G. Fleck

2001-08-01

Full Text Available A absorção vegetal do nitrogênio (N presente no solo ou fornecido via fertilização é regulada por um complexo enzimático que age de forma conjunta e ordenada na planta. O objetivo desta pesquisa foi investigar efeitos dos herbicidas atrazine e glufosinate de amônio na absorção do N pelas plantas e os efeitos que exercem em características de plantas de milho. Em um dos experimentos (experimento 1 foram testadas três doses de atrazine (0, 200 e 2.000 g i.a. ha-1 e de glufosinate de amônio (0; 40 e 80 g i.a. ha-1 e duas doses de N (0 e 90 kg ha-1. No segundo experimento (experimento 2 foram testados três tratamentos herbicidas (atrazine, 200 g i.a. ha-1; glufosinate de amônio, 40 g i.a. ha-1; atrazine + glufosinate de amônio, 200 + 40 g i.a. ha-1; e testemunha, duas fontes de N (uréia e nitrato de amônio e duas doses de N (0 e 100 kg ha-1. Os efeitos dos tratamentos foram avaliados aos 10 e 20 dias após a aplicação (DAA dos herbicidas, no experimento 1, e quando as plantas de milho apresentavam 10 folhas desenvolvidas (15 DAA e no pendoamento do milho (40 DAA, no experimento 2. A partir da análise dos resultados obtidos, constatou-se que aplicação de N em cobertura na cultura do milho promove aumento na maioria dos componentes do rendimento e incrementa em 35% o rendimento de grãos e que esse efeito ocorre de forma independente da fonte de N utilizada: uréia ou nitrato de amônio. Não ocorre interação entre os fatores relacionados aos herbicidas inibidores do fotossistema II (atrazine e da síntese de glutamina (glufosinate de amônio e aplicação de N em cobertura no milho. O uso destes herbicidas em doses reduzidas (abaixo da recomendada, aplicados isoladamente ou combinados, não afetou o rendimento de grãos nem os componentes do rendimento da cultura do milho. O herbicida atrazine tem pequena influência nos teores de clorofila e de N em milho, mas, em algumas situações, sua ação é favorável, especialmente

Toxicity of three selected pesticides (Alachlor, Atrazine and Diuron ...

African Journals Online (AJOL)

The present study aimed to evaluate acute toxicity tests for three selected herbicides: Alachlor, Atrazine and Diuron using turbot flatfish. Larvae were more sensitive than turbot embryos to all pesticides. Median lethal concentrations of the selected pesticides during a 48 h and 96 h exposure for turbot embryos and larvae ...

Atrazine affects kidney and adrenal hormones (AHs) related genes expressions of rare minnow (Gobiocypris rarus).

Science.gov (United States)

Yang, Lihua; Zha, Jinmiao; Li, Wei; Li, Zhaoli; Wang, Zijian

2010-05-05

Atrazine, one of the most widely used herbicides, has been proved to interfere with sexual hormones. However few studies have considered the effects of atrazine on adrenal hormones (AH). In this study, rare minnow (Gobiocypris rarus) was exposed to 0, 3, 10, 33, 100 and 333microg/l atrazine for 28 days. The histopathology of kidney and gill was examined and the expressions of AHs-related genes including Na(+),K(+)-ATPase, glucocorticoid receptor (gr), heat shock protein 70 (hsp70), and heat shock protein 90 (hsp90) in kidney and gill were quantitatively determined. Histopathological observation revealed obvious lesions in gill including hyperplasia, necrosis in epithelium region, aneurysm and lamellar fusion at concentrations as low as 10microg/l. The observed lesions in kidney included extensive expansion in the lumen, degenerative and necrotic changes of the tubular epithelia, shrinkage of the glomerulus as well as increase of the Bowman's space at concentrations as low as 10microg/l. The expressions of Na(+),K(+)-ATPase, gr, hsp70 and hsp90 in the kidney of females were significantly decreased at all concentrations. For males, the expressions of hsp90 in the kidney of all treated groups were significantly down-regulated, while gr at all concentrations and hsp70 at 10, 33, 100microg/l were significantly up-regulated. However in the gill, the expressions of these genes were not significantly different from the control. These results indicated that exposure to atrazine caused impairments of kidney and gill of fish at environmental related concentrations. Histopathological lesions could partly attribute to the changes of the expressions of AHs-related genes in kidney. We concluded also that atrazine is a potential AHs-disruptor and AHs-related genes in kidney of fish could be used as sensitive molecular biomarkers.

Atrazine affects kidney and adrenal hormones (AHs) related genes expressions of rare minnow (Gobiocypris rarus)

Energy Technology Data Exchange (ETDEWEB)

Yang Lihua; Zha Jinmiao; Li Wei; Li Zhaoli [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, P.O. Box 2871, Beijing 100085 (China); Wang Zijian, E-mail: wangzj@rcees.ac.cn [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Shuangqing Road 18, P.O. Box 2871, Beijing 100085 (China)

2010-05-05

Atrazine, one of the most widely used herbicides, has been proved to interfere with sexual hormones. However few studies have considered the effects of atrazine on adrenal hormones (AH). In this study, rare minnow (Gobiocypris rarus) was exposed to 0, 3, 10, 33, 100 and 333 {mu}g/l atrazine for 28 days. The histopathology of kidney and gill was examined and the expressions of AHs-related genes including Na{sup +},K{sup +}-ATPase, glucocorticoid receptor (gr), heat shock protein 70 (hsp70), and heat shock protein 90 (hsp90) in kidney and gill were quantitatively determined. Histopathological observation revealed obvious lesions in gill including hyperplasia, necrosis in epithelium region, aneurysm and lamellar fusion at concentrations as low as 10 {mu}g/l. The observed lesions in kidney included extensive expansion in the lumen, degenerative and necrotic changes of the tubular epithelia, shrinkage of the glomerulus as well as increase of the Bowman's space at concentrations as low as 10 {mu}g/l. The expressions of Na{sup +},K{sup +}-ATPase, gr, hsp70 and hsp90 in the kidney of females were significantly decreased at all concentrations. For males, the expressions of hsp90 in the kidney of all treated groups were significantly down-regulated, while gr at all concentrations and hsp70 at 10, 33, 100 {mu}g/l were significantly up-regulated. However in the gill, the expressions of these genes were not significantly different from the control. These results indicated that exposure to atrazine caused impairments of kidney and gill of fish at environmental related concentrations. Histopathological lesions could partly attribute to the changes of the expressions of AHs-related genes in kidney. We concluded also that atrazine is a potential AHs-disruptor and AHs-related genes in kidney of fish could be used as sensitive molecular biomarkers.

Atrazine affects kidney and adrenal hormones (AHs) related genes expressions of rare minnow (Gobiocypris rarus)

International Nuclear Information System (INIS)

Yang Lihua; Zha Jinmiao; Li Wei; Li Zhaoli; Wang Zijian

2010-01-01

Atrazine, one of the most widely used herbicides, has been proved to interfere with sexual hormones. However few studies have considered the effects of atrazine on adrenal hormones (AH). In this study, rare minnow (Gobiocypris rarus) was exposed to 0, 3, 10, 33, 100 and 333 μg/l atrazine for 28 days. The histopathology of kidney and gill was examined and the expressions of AHs-related genes including Na + ,K + -ATPase, glucocorticoid receptor (gr), heat shock protein 70 (hsp70), and heat shock protein 90 (hsp90) in kidney and gill were quantitatively determined. Histopathological observation revealed obvious lesions in gill including hyperplasia, necrosis in epithelium region, aneurysm and lamellar fusion at concentrations as low as 10 μg/l. The observed lesions in kidney included extensive expansion in the lumen, degenerative and necrotic changes of the tubular epithelia, shrinkage of the glomerulus as well as increase of the Bowman's space at concentrations as low as 10 μg/l. The expressions of Na + ,K + -ATPase, gr, hsp70 and hsp90 in the kidney of females were significantly decreased at all concentrations. For males, the expressions of hsp90 in the kidney of all treated groups were significantly down-regulated, while gr at all concentrations and hsp70 at 10, 33, 100 μg/l were significantly up-regulated. However in the gill, the expressions of these genes were not significantly different from the control. These results indicated that exposure to atrazine caused impairments of kidney and gill of fish at environmental related concentrations. Histopathological lesions could partly attribute to the changes of the expressions of AHs-related genes in kidney. We concluded also that atrazine is a potential AHs-disruptor and AHs-related genes in kidney of fish could be used as sensitive molecular biomarkers.

Differential metamorphosis alters the endocrine response in anuran larvae exposed to T3 and atrazine

International Nuclear Information System (INIS)

Freeman, Jennifer L.; Beccue, Nathan; Rayburn, A. Lane

2005-01-01

Pesticide chemical contamination is one of the suspected contributors of the amphibian population decline. The herbicide atrazine is one of the major surface water contaminants in the U.S. A previous study has shown that atrazine at concentrations as low as 100 parts per billion (ppb) increased the time to metamorphosis in Xenopus laevis tadpoles. However, questions remain as to the applicability of a study of a non-native species to a native organism. The possible effects of atrazine on developing Bufo americanus were explored. Atrazine at potentially (albeit high) environmental concentrations was found not to delay the metamorphosis of developing B. americanus tadpoles as observed in X. laevis. Several studies have indicated that atrazine affects thyroid hormones. Since thyroid hormones are critical in amphibian metamorphosis, B. americanus and X. laevis tadpoles were exposed to exogenous 3,5,3'-triiodothyronine (T 3 ). X. laevis were found to be more responsive to the effects of exogenous T 3 compared to B. americanus, indicating that X. laevis may be more sensitive to endocrine active chemicals than B. americanus. In X. laevis, nuclear heterogeneity has been associated with metamorphosis. Flow cytometric analysis of the nuclei of normal metamorphing B. americanus indicates a decrease in the amount of thyroid mediated chromatin alterations relative to the nuclei of metamorphing X. laevis. Indications are that the differential response to endocrine disruption is due to the differential role of chromatin associated gene expression during metamorphosis of B. americanus versus X. laevis. A second native species, Hyla versicolor, was observed to have the X. laevis nuclear pattern with respect to metamorphosis. As such, sensitivity to endocrine disruption is hypothesized not to be limited to laboratory non-native species

Acceleration transforms and statistical kinetic models

International Nuclear Information System (INIS)

LuValle, M.J.; Welsher, T.L.; Svoboda, K.

1988-01-01

For a restricted class of problems a mathematical model of microscopic degradation processes, statistical kinetics, is developed and linked through acceleration transforms to the information which can be obtained from a system in which the only observable sign of degradation is sudden and catastrophic failure. The acceleration transforms were developed in accelerated life testing applications as a tool for extrapolating from the observable results of an accelerated life test to the dynamics of the underlying degradation processes. A particular concern of a physicist attempting to interpreted the results of an analysis based on acceleration transforms is determining the physical species involved in the degradation process. These species may be (a) relatively abundant or (b) relatively rare. The main results of this paper are a theorem showing that for an important subclass of statistical kinetic models, acceleration transforms cannot be used to distinguish between cases a and b, and an example showing that in some cases falling outside the restrictions of the theorem, cases a and b can be distinguished by their acceleration transforms

The effects of gestational and chronic atrazine exposure on motor behaviors and striatal dopamine in male Sprague-Dawley rats

Energy Technology Data Exchange (ETDEWEB)

Walters, Jennifer L., E-mail: Jennifer.l.walters@wmich.edu [Western Michigan University, Department of Psychology, 1903 W Michigan Ave, Kalamazoo, MI 49008-5439 (United States); Lansdell, Theresa A., E-mail: lansdel1@msu.edu [Michigan State University, Department of Pharmacology and Toxicology, 1355 Bogue Street, East Lansing, MI 48824 (United States); Lookingland, Keith J., E-mail: lookingl@msu.edu [Michigan State University, Department of Pharmacology and Toxicology, 1355 Bogue Street, East Lansing, MI 48824 (United States); Baker, Lisa E., E-mail: lisa.baker@wmich.edu [Western Michigan University, Department of Psychology, 1903 W Michigan Ave, Kalamazoo, MI 49008-5439 (United States)

2015-12-01

This study sought to investigate the effects of environmentally relevant gestational followed by continued chronic exposure to the herbicide, atrazine, on motor function, cognition, and neurochemical indices of nigrostriatal dopamine (DA) activity in male rats. Dams were treated with 100 μg/kg atrazine, 10 mg/kg atrazine, or vehicle on gestational day 1 through postnatal day 21. Upon weaning, male offspring continued daily vehicle or atrazine gavage treatments for an additional six months. Subjects were tested in a series of behavioral assays, and 24 h after the last treatment, tissue samples from the striatum were analyzed for DA and 3,4-dihydroxyphenylacetic acid (DOPAC). At 10 mg/kg, this herbicide was found to produce modest disruptions in motor functioning, and at both dose levels it significantly lowered striatal DA and DOPAC concentrations. These results suggest that exposures to atrazine have the potential to disrupt nigrostriatal DA neurons and behaviors associated with motor functioning. - Highlights: • Male rats received gestational and chronic exposure to ATZ (10 mg/kg and 100 μg/kg). • ATZ altered locomotor activity and impaired motor coordination. • ATZ lowered striatal DA and DOPAC concentrations. • ATZ produced a potential anxiogenic effect. • ATZ did not impair performance in learning and memory assessments.

The effects of gestational and chronic atrazine exposure on motor behaviors and striatal dopamine in male Sprague-Dawley rats

International Nuclear Information System (INIS)

Walters, Jennifer L.; Lansdell, Theresa A.; Lookingland, Keith J.; Baker, Lisa E.

2015-01-01

This study sought to investigate the effects of environmentally relevant gestational followed by continued chronic exposure to the herbicide, atrazine, on motor function, cognition, and neurochemical indices of nigrostriatal dopamine (DA) activity in male rats. Dams were treated with 100 μg/kg atrazine, 10 mg/kg atrazine, or vehicle on gestational day 1 through postnatal day 21. Upon weaning, male offspring continued daily vehicle or atrazine gavage treatments for an additional six months. Subjects were tested in a series of behavioral assays, and 24 h after the last treatment, tissue samples from the striatum were analyzed for DA and 3,4-dihydroxyphenylacetic acid (DOPAC). At 10 mg/kg, this herbicide was found to produce modest disruptions in motor functioning, and at both dose levels it significantly lowered striatal DA and DOPAC concentrations. These results suggest that exposures to atrazine have the potential to disrupt nigrostriatal DA neurons and behaviors associated with motor functioning. - Highlights: • Male rats received gestational and chronic exposure to ATZ (10 mg/kg and 100 μg/kg). • ATZ altered locomotor activity and impaired motor coordination. • ATZ lowered striatal DA and DOPAC concentrations. • ATZ produced a potential anxiogenic effect. • ATZ did not impair performance in learning and memory assessments.

Extended fish short term reproduction assays with the fathead minnow and Japanese medaka: No evidence of impaired fecundity from exposure to atrazine.

Science.gov (United States)

Brain, Richard A; Schneider, Suzanne Z; Anderson, Julie C; Knopper, Loren D; Wolf, Jeffrey C; Hanson, Mark L

2018-08-01

Short-term reproduction assays were conducted with fathead minnow (Pimephales promelas) and Japanese medaka (Oryzias latipes) to evaluate responses from atrazine exposure at environmentally relevant concentrations and above. Breeding groups of fish with multiple males and females were exposed to atrazine under flow-through conditions. Fathead minnows were exposed to mean measured concentrations of 1.0, 10, 26, 52, and 105 μg atrazine/L for 28 days. Medaka were exposed to mean measured concentrations of 9.4, 48, 74, 97, and 244 μg atrazine/L for 28 or 29 days. Fish were evaluated for survival, fecundity, fertility, total length, wet weight, secondary sex characteristics, gonadosomatic index (GSI) (P. promelas only), plasma or hepatic vitellogenin (VTG), and histopathology of gonads. General observations of health and behaviour were also conducted. There were no statistically significant effects (i.e., p < 0.05) of atrazine on survival, size, reproduction, behaviour, GSI, VTG, or secondary sex characteristics in either species at any exposure level. In fathead minnows, there were no histopathological findings associated with atrazine exposure in male fish, but there was an increased proportion of Stage 4.0 ovaries accompanied by an increase in proportion of Grade 3 post-ovulatory follicles in females of the 105 μg/L treatment group. Without a concomitant increase in oocyte atresia, neither of these findings are considered adverse for the health of the fish. In medaka, there were no significant effects of atrazine exposure on histopathology in either sex. These data support current weight-of-evidence assessments that atrazine does not cause direct adverse effects on fish reproduction at environmentally realistic concentrations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.

Science.gov (United States)

Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

2013-09-01

In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2 days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2 days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of repeated long term application of atrazine on soil properties and bound residues formation

International Nuclear Information System (INIS)

Behki, R.; Khan, S.U.

2001-01-01

The effect of repeated long term application of the herbicide atrazine on the activities of microorganisms, enzymes, as well as on the bound residues formation, was investigated. Bacteria, fungi and soil respiration were in general inhibited in the first year of application. However, in the second and third year no such trend was observed. Similarly, a decreasing trend in the Fe(III)-reduction, nitrification and arginine deamination was observed in the first year whereas in the subsequent two years no such trend was prominent. The dehydrogenase and arylsulfatase activities showed an increasing trend after the application of the herbicide. Column studies showed that extractable residues of atrazine and carbofuran gradually decreased after the application of the pesticides. Amendments of the soil containing 14 C-bound residues did not increase 14 CO 2 evolution. Unextractable 14 C was higher and mineralization of 14 C-2,4-D was lower in previously untreated soil than in soils with histories of atrazine and carbofuran application. (author)

Effects of in ovo exposure of Imazalil and Atrazine on sexual differentiation in chick gonads

Energy Technology Data Exchange (ETDEWEB)

Yamashita, J.; Ikeda, M. [Univ. of Shizuoka, Shizuoka (Japan); Matsushita, S.; Iwasawa, T.; Ikeya, M. [Shizuoka Swine and Poultry Experiment Station, Kikugawa (Japan)

2004-09-15

numerous anti-fungal chemicals. These chemicals have shown to reversibly (although not necessarily competitively) inhibit aromatase activity in human placental microsomes. It is reported that imazalil and difenoconazole inhibit aromatase activity in human adrenocortical carcinoma cell line H295R. Atrazine is the most commonly used herbicide in the word. There are several reports about the adverse effects of atrazine exposure. Atrazine induced hermaphroditism in African clawed frogs and demasculinized the larynx in male frogs. Plasma testosterone concentration in male frogs was decreased by atrazine exposure, and plasma estradiol concentration in rats was increased by atrazine exposure. Atrazine also increased aromatase activity in human adrenocortical carcinoma cell line H295R by inducing aromatase mRNA. In this study, the effects of in ovo exposure to an aromatase-inhibiting chemical (imazalil) and an aromatase-activating chemical (atrazine) on the sexual differentiation of chick gonad were investigated.

Differential metamorphosis alters the endocrine response in anuran larvae exposed to T{sub 3} and atrazine

Energy Technology Data Exchange (ETDEWEB)

Freeman, Jennifer L. [University of Illinois, Department of Crop Sciences, 1201 W. Gregory Drive, 320 ERML, Urbana, IL 61801 (United States); Beccue, Nathan [University of Illinois, Department of Crop Sciences, 1201 W. Gregory Drive, 320 ERML, Urbana, IL 61801 (United States); Rayburn, A. Lane [University of Illinois, Department of Crop Sciences, 1201 W. Gregory Drive, 320 ERML, Urbana, IL 61801 (United States)]. E-mail: arayburn@uiuc.edu

2005-11-10

Pesticide chemical contamination is one of the suspected contributors of the amphibian population decline. The herbicide atrazine is one of the major surface water contaminants in the U.S. A previous study has shown that atrazine at concentrations as low as 100 parts per billion (ppb) increased the time to metamorphosis in Xenopus laevis tadpoles. However, questions remain as to the applicability of a study of a non-native species to a native organism. The possible effects of atrazine on developing Bufo americanus were explored. Atrazine at potentially (albeit high) environmental concentrations was found not to delay the metamorphosis of developing B. americanus tadpoles as observed in X. laevis. Several studies have indicated that atrazine affects thyroid hormones. Since thyroid hormones are critical in amphibian metamorphosis, B. americanus and X. laevis tadpoles were exposed to exogenous 3,5,3'-triiodothyronine (T{sub 3}). X. laevis were found to be more responsive to the effects of exogenous T{sub 3} compared to B. americanus, indicating that X. laevis may be more sensitive to endocrine active chemicals than B. americanus. In X. laevis, nuclear heterogeneity has been associated with metamorphosis. Flow cytometric analysis of the nuclei of normal metamorphing B. americanus indicates a decrease in the amount of thyroid mediated chromatin alterations relative to the nuclei of metamorphing X. laevis. Indications are that the differential response to endocrine disruption is due to the differential role of chromatin associated gene expression during metamorphosis of B. americanus versus X. laevis. A second native species, Hyla versicolor, was observed to have the X. laevis nuclear pattern with respect to metamorphosis. As such, sensitivity to endocrine disruption is hypothesized not to be limited to laboratory non-native species.

Sorption mechanisms of phenanthrene, lindane, and atrazine with various humic acid fractions from a single soil sample.

Science.gov (United States)

Wang, Xilong; Guo, Xiaoying; Yang, Yu; Tao, Shu; Xing, Baoshan

2011-03-15

The sorption behavior of organic compounds (phenanthrene, lindane, and atrazine) to sequentially extracted humic acids and humin from a peat soil was examined. The elemental composition, XPS and (13)C NMR data of sorbents combined with sorption isotherm data of the tested compounds show that nonspecific interactions govern sorption of phenanthrene and lindane by humic substances. Their sorption is dependent on surface and bulk alkyl carbon contents of the sorbents, rather than aromatic carbon. Sorption of atrazine by these sorbents, however, is regulated by polar interactions (e.g., hydrogen bonding). Carboxylic and phenolic moieties are key components for H-bonding formation. Thermal analysis reveals that sorption of apolar (i.e., phenanthrene and lindane) and polar (i.e., atrazine) compounds by humic substances exhibit dissimilar relationships with condensation and thermal stability of sorption domains, emphasizing the major influence of domain spatial arrangement on sorption of organic compounds with distinct polarity. Results of pH-dependent sorption indicate that reduction in sorption of atrazine by the tested sorbents is more evident than phenanthrene with increasing pH, supporting the dependence of organic compound sorption on its polarity and structure. This study highlights the different interaction mechanisms of apolar and polar organic compounds with humic substances.

Effects of tillage and application rate on atrazine transport to subsurface drainage: Evaluation of RZWQM using a six-year field study

Science.gov (United States)

Malone, Robert W.; Nolan, Bernard T.; Ma, Liwang; Kanwar, Rameshwar S.; Pederson, Carl H.; Heilman, Philip

2014-01-01

Well tested agricultural system models can improve our understanding of the water quality effects of management practices under different conditions. The Root Zone Water Quality Model (RZWQM) has been tested under a variety of conditions. However, the current model's ability to simulate pesticide transport to subsurface drain flow over a long term period under different tillage systems and application rates is not clear. Therefore, we calibrated and tested RZWQM using six years of data from Nashua, Iowa. In this experiment, atrazine was spring applied at 2.8 (1990–1992) and 0.6 kg/ha/yr (1993–1995) to two 0.4 ha plots with different tillage (till and no-till). The observed and simulated average annual flow weighted atrazine concentrations (FWAC) in subsurface drain flow from the no-till plot were 3.7 and 3.2 μg/L, respectively for the period with high atrazine application rates, and 0.8 and 0.9 μg/L, respectively for the period with low application rates. The 1990–1992 observed average annual FWAC difference between the no-till and tilled plot was 2.4 μg/L while the simulated difference was 2.1 μg/L. These observed and simulated differences for 1993–1995 were 0.1 and 0.1 μg/L, respectively. The Nash–Sutcliffe model performance statistic (EF) for cumulative atrazine flux to subsurface drain flow was 0.93 for the no-till plot testing years (1993–1995), which is comparable to other recent model tests. The value of EF is 1.0 when simulated data perfectly match observed data. The order of selected parameter sensitivity for RZWQM simulated FWAC was atrazine partition coefficient > number of macropores > atrazine half life in soil > soil hydraulic conductivity. Simulations from 1990 to 1995 with four different atrazine application rates applied at a constant rate throughout the simulation period showed concentrations in drain flow for the no-till plot to be twice those of the tilled plot. The differences were more pronounced in the early

Lifetime prediction and reliability estimation methodology for Stirling-type pulse tube refrigerators by gaseous contamination accelerated degradation testing

Science.gov (United States)

Wan, Fubin; Tan, Yuanyuan; Jiang, Zhenhua; Chen, Xun; Wu, Yinong; Zhao, Peng

2017-12-01

Lifetime and reliability are the two performance parameters of premium importance for modern space Stirling-type pulse tube refrigerators (SPTRs), which are required to operate in excess of 10 years. Demonstration of these parameters provides a significant challenge. This paper proposes a lifetime prediction and reliability estimation method that utilizes accelerated degradation testing (ADT) for SPTRs related to gaseous contamination failure. The method was experimentally validated via three groups of gaseous contamination ADT. First, the performance degradation model based on mechanism of contamination failure and material outgassing characteristics of SPTRs was established. Next, a preliminary test was performed to determine whether the mechanism of contamination failure of the SPTRs during ADT is consistent with normal life testing. Subsequently, the experimental program of ADT was designed for SPTRs. Then, three groups of gaseous contamination ADT were performed at elevated ambient temperatures of 40 °C, 50 °C, and 60 °C, respectively and the estimated lifetimes of the SPTRs under normal condition were obtained through acceleration model (Arrhenius model). The results show good fitting of the degradation model with the experimental data. Finally, we obtained the reliability estimation of SPTRs through using the Weibull distribution. The proposed novel methodology enables us to take less than one year time to estimate the reliability of the SPTRs designed for more than 10 years.

Atrazine- tolerant native microorganisms isolated from agricultural soils in the department of Cordoba, Colombia

Directory of Open Access Journals (Sweden)

Luis Oviedo Z

2017-05-01

Full Text Available The objective of the present study was to identify and evaluate atrazine tolerant native microorganisms isolated from a soil destined to the maize crop for ensiling, where this pesticide is usually used as preemergence. To determine their tolerance, they were subjected to growth at different concentrations of atrazine, different temperatures (30 ° C, 37 ° C and 40 ° C and pH (5.0, 6.0 and 9.0. The results show native strains that tolerated concentrations of 1000 ppm atrazine, identified as Pseudomonas sp (strain 1L1a, Pseudomona sp (strain 1L2, Streptomyces sp and Arthrobacterium sp, which show higher growth at 37 °C (7. 98E+06 CFU/mL, lower at 30 °C (3.63E+06 CFU/mL and tolerance at 40 °C (5.80E+06 CFU/mL. The strain Streptomyces sp reached its highest growth (4.73E+06 UFC/mL at pH 9.0, while Pseudomonas sp strain 1L1a (3.43E+06 UFC/mL, Arthrobacter sp (3.40E+06 UFC/mL and Pseudomonas sp strain 1L2a (2.63E+06 CFU/mL was at pH 6.0. All microorganisms showed sensitivity to pH 5.0. The growths reached at different temperatures and pH are in agreement with the adaptation to the tropical climate predominant in the region and related to the genus of microorganisms. The study indicates that the native strains are able to tolerate high concentrations of atrazine and to mineralize it in soils with low content of organic matter and nutrients.

Pesticide Degrading Bacteria in Aquatic Environment: Bioprospecting and Evaluation of Biotechnological Potential

Directory of Open Access Journals (Sweden)

Daniel Rodrigues dos Santos

2016-07-01

Full Text Available Pesticides play an important role in the increase of productivity in agro-industry and the extensive use of these substances cause environmental, economic and social damage in time. Microbial activity is an essential part in the dynamics and the destination of pesticides in the environment. This research focuses in prospecting and characterizing bacterial strains which are potentially able to degrade/tolerate Atrazine, Chlorpyrifos, Methyl parathion and Picloram. Bacteria were isolated from water samples collected according to the degree of salinity along the Pacoti River's estuary (Ceara, located in the semi-arid region of northeastern Brazil. A total of 49 bacterial strains were isolated, all of which tolerated/ downgraded concentrations up to 200mg/L of picloram, atrazine and methyl parathion. Tested in pesticide mixtures, the percentage and tolerance level showed that 73% grew in concentrations up to 200mg/L, 17,4% tolerated/ downgraded up to 150ml/L and the remainder only grew in concentrations under 100ml/L. The strains which had the best performance against pesticides, by points, were P1 (13Db e 14D; P2 (10E; P3 (2M, 9M, 10M, 12Mb, 14M, 17M 18Mp 19M e 20M. A high percentage of isolates (67% expressed luminescence when exposed to the pesticides atrazine and methyl parathion in concentrations between 150 and 200ml/L. DOI: http://dx.doi.org/10.17807/orbital.v8i4.748

Atrazine and nitrate in drinking water and the risk of preterm delivery and low birth weight in four Midwestern states

DEFF Research Database (Denmark)

Stayner, Leslie Thomas; Almberg, Kirsten; Jones, Rachael

2017-01-01

Background: Atrazine and nitrate are common contaminants in water, and there is limited evidence that they are associated with adverse birth outcomes. The objective of this study was to examine whether atrazine and nitrate in water are associated with an increased risk of preterm delivery (PTD...... weeks), term LBW (nitrate in finished water. Multivariable negative binomial models were fitted to examine the association...... between the exposures and the adverse birth outcomes. Models were fitted with varying restrictions on the percentage of private well usage in the counties in order to limit the degree of exposure misclassification. Results: Estimated water concentrations of atrazine (mean=0.42 ppb) and nitrate (mean=0...

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method.

Science.gov (United States)

Qian, Cheng; Fan, Jiajie; Fang, Jiayi; Yu, Chaohua; Ren, Yi; Fan, Xuejun; Zhang, Guoqi

2017-10-16

By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample's rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method

Science.gov (United States)

Yu, Chaohua; Fan, Xuejun; Zhang, Guoqi

2017-01-01

By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample’s rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs. PMID:29035300

Ação dos herbicidas atrazine e glufosinate de amônio no aproveitamento de nitrogênio pelas plantas de milho Herbicides atrazine and ammonium glufosinate action on nitrogen usage by corn plants

OpenAIRE

N.G. Fleck; M.A. Rizzardi; R. Neves; D. Agostinetto

2001-01-01

A absorção vegetal do nitrogênio (N) presente no solo ou fornecido via fertilização é regulada por um complexo enzimático que age de forma conjunta e ordenada na planta. O objetivo desta pesquisa foi investigar efeitos dos herbicidas atrazine e glufosinate de amônio na absorção do N pelas plantas e os efeitos que exercem em características de plantas de milho. Em um dos experimentos (experimento 1) foram testadas três doses de atrazine (0, 200 e 2.000 g i.a. ha-1) e de glufosinate de amônio (...

Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff

Science.gov (United States)

Lydy, Michael J.; Carter, D.S.; Crawford, Charles G.

1996-01-01

Gas chromatography/mass spectrometry (GC/MS) and enzyme-linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992–September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett-Packard 5971 A, with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction; ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 μg/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application.

Green Tea Protects Testes against Atrazine-induced Toxicity in Rat

Directory of Open Access Journals (Sweden)

Reza Kheirandish

2017-06-01

Full Text Available Background: Atrazine (ATZ is a common herbicide in agriculture for control of grass and broad-leaved weeds. It persists in the environment and causes reproductive problems in both human and animals. The present study was aimed at protective effect of green tea against ATZ toxicity in the reproductive system of male rats. Methods: The present study was performed in Veterinary School, Shahid Bahonar University of Kerman in 2016. ATZ and treatment groups received ATZ daily 200 mg/kg BW orally for 14 d. In addition, 0.2% methanolic green tea extract was administrated in the treatment group. Results: In histopathologic investigation, number of germinal layers reduced in the most seminiferous tubules in the ATZ group and spermatids were absence. Necrotic spermatocytes, spermatids, and spermatozoa were evident in the testicular tubules. In the morphometric measurements, tubular diameter, germinal epithelium height, and meiosis index decreased significantly. Conclusion: Green tea extract had reduced testicular toxicity of atrazine significantly. ATZ induces toxicity through oxidative damage and green tea extract can protect the testes due to antioxidant activity of its polyphenols especially flavonoids.

Bioremediation model for atrazine contaminated agricultural soils using phytoremediation (using Phaseolus vulgaris L.) and a locally adapted microbial consortium.

Science.gov (United States)

Madariaga-Navarrete, Alfredo; Rodríguez-Pastrana, Blanca Rosa; Villagómez-Ibarra, José Roberto; Acevedo-Sandoval, Otilio Arturo; Perry, Gregory; Islas-Pelcastre, Margarita

2017-06-03

The objective of the present study was to examine a biological model under greenhouse conditions for the bioremediation of atrazine contaminated soils. The model consisted in a combination of phytoremediation (using Phaseolus vulgaris L.) and rhizopheric bio-augmentation using native Trichoderma sp., and Rhizobium sp. microorganisms that showed no inhibitory growth at 10,000 mg L -1 of herbicide concentration. 33.3 mg of atrazine 50 g -1 of soil of initial concentration was used and an initial inoculation of 1 × 10 9 UFC mL -1 of Rhizobium sp. and 1 × 10 5 conidia mL -1 of Trichoderma sp. were set. Four treatments were arranged: Bean + Trichoderma sp. (B+T); Bean + Rhizobium sp. (BR); Bean + Rhizobium sp. + Trichoderma sp. (B+R+T) and Bean (B). 25.51 mg of atrazine 50 g -1 of soil (76.63%) was removed by the B+T treatment in 40 days (a = 0.050, Tukey). This last indicate that the proposed biological model and methodology developed is useful for atrazine contaminated bioremediation agricultural soils, which can contribute to reduce the effects of agrochemical abuse.

Evaluation of atrazine plus isoxaflutole (Atoll®) mixture for weed ...

African Journals Online (AJOL)

Field experiments were set up in three ecological zones of southwestern Nigeria to evaluate the effectiveness of Atoll® (atrazine + isoxaflutole), a new herbicide mixture, for weed control in maize. Crop i njury rating indicated pronounced phytotoxic effect on crops from 1.34 to 1.61 kg a.i. ha-1 Atoll in all locations. Acceptable ...

Effect of atrazine (Herbicide) on blood parameters of common carp ...

African Journals Online (AJOL)

EJIRO

could be used as an important tool for the assessment of pathological conditions of fish. ... agricultural or industrial areas have high probability of ... The use of herbicides to control aquatic weeds has ... Five hundred fish were stocked in a large cement tank (4 m × 6 m × 3 m) ..... Ecological risk assessment of atrazine in North.

Effects of atrazine on egg masses of the yellow-spotted salamander (Ambystoma maculatum) and its endosymbiotic alga (Oophila amblystomatis)

International Nuclear Information System (INIS)

Baxter, Leilan; Brain, Richard A.; Hosmer, Alan J.; Nema, Mohini; Müller, Kirsten M.; Solomon, Keith R.; Hanson, Mark L.

2015-01-01

Embryonic growth of the yellow-spotted salamander (Ambystoma maculatum) is enhanced by the presence of the green alga Oophila amblystomatis, in the egg capsule. To further assess potential impacts of herbicides on this relationship, A. maculatum egg masses were exposed to atrazine (0–338 μg/L) until hatching (up to 66 days). Exposure to atrazine reduced PSII yield of the symbiotic algae in a concentration-dependent manner, but did not significantly affect visible algal growth or any metrics associated with salamander development. Algal cells were also cultured in the laboratory for toxicity testing. In the 96-h growth inhibition test (0–680 μg/L), ECx values were generally greater than those reported for standard algal test species. Complete recovery of growth rates occurred within 96-h of transferring cells to untreated media. Overall, development of A. maculatum embryos was not affected by exposure to atrazine at concentrations and durations exceeding those found in the environment. - Highlights: • The yellow-spotted salamander produces eggs that are colonized by a symbiotic green alga. • We tested the sensitivity of this system to the herbicide atrazine. • Embryo development was not significantly affected by exposure at up to 300 μg/L. • The alga was isolated and 96-h growth tests were performed in the laboratory. • EC50s for Oophila sp. were >100 μg/L. - Development of Ambystoma maculatum embryos in egg masses was not impacted by exposure to atrazine at concentrations and durations exceeding those commonly found in the environment.

Bound residues in corn plants treated with 14C-atrazine and bioavailability to rats

International Nuclear Information System (INIS)

Khan, S.U.

1986-01-01

Corn plants, about 3.5 months old and treated with 14 C-atrazine, were used in an experiment in which the aerial portion of the plants was exhaustively extracted with solvents. The extracted dried material containing bound 14 C-residues was fed to rats. The extracted aerial portion of control corn plants fortified with 14 C-atrazine was also fed to rats. After four days, 88% and 32% of the radioactivity was excreted in the faeces, and 10% and 60% radioactivity was voided in the urine from rats fed plant material containing bound and fortified 14 C-residues, respectively. The data suggest that the bioavailability to rats of bound 14 C-residues in corn material is low. (author)

Review of Atrazine Sampling by POCIS and Chemcatcher.

Science.gov (United States)

Booij, Kees; Chen, Sunmao

2018-04-24

A key success factor for the performance of passive samplers is the proper calibration of sampling rates. Sampling rates for a wide range of polar organic compounds are available for Chemcatchers and polar organic chemical integrative samplers (POCIS), but the mechanistic models that are needed to understand the effects of exposure conditions on sampling rates need improvement. Literature data on atrazine sampling rates by these samplers were reviewed with the aim to assess what can be learned from literature reports of this well studied compound and to identify knowledge gaps related to the effects of flow and temperature. The flow dependency of sampling rates could be described by a mass transfer resistance model with one (POCIS) or two (Chemcatcher) adjustable parameters. Literature data were insufficient to evaluate the temperature effect on the sampling rates. An evaluation of reported sampler configurations showed that standardization of sampler design can be improved: for POCIS with respect to surface area and sorbent mass, and for Chemcatcher with respect to housing design. Several reports on atrazine sampling could not be used because the experimental setups were insufficiently described with respect to flow conditions. Recommendations are made for standardization of sampler layout and documentation of flow conditions in calibration studies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

First muon acceleration using a radio-frequency accelerator

Directory of Open Access Journals (Sweden)

S. Bae

2018-05-01

Full Text Available Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}, which are bound states of positive muons (μ^{+} and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ. In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

A degradation approach to accelerate simulations to steady-state in a 3-D tracer transport model of the global ocean

Energy Technology Data Exchange (ETDEWEB)

Aumont, O.; Orr, J.C.; Marti, O. [CEA Saclay, Gif-sur-Yvette (France). Lab. de Modelisation du Climat et de l`Environnement; Jamous, D.; Monfray, P. [Centre des Faibles Radioactivites, Laboratoire mixte CNRS-CEA, L`Orme des Merisiers, Bt. 709/LMCE, CE Saclay, F-91191 Gif sur Yvette Cedex (France); Madec, G. [Laboratoire d`Oceanographie Dynamique et de Climatologie, (CNRS/ORSTOM/UPMC) Universite Paris VI, 4 place Jussieu, Paris (France)

1998-02-01

We have developed a new method to accelerate tracer simulations to steady-state in a 3D global ocean model, run off-line. Using this technique, our simulations for natural {sup 14}C ran 17 times faster when compared to those made with the standard nonaccelerated approach. For maximum acceleration we wish to initialize the model with tracer fields that are as close as possible to the final equilibrium solution. Our initial tracer fields were derived by judiciously constructing a much faster, lower-resolution (degraded), off-line model from advective and turbulent fields predicted from the parent on-line model, an ocean general circulation model (OGCM). No on-line version of the degraded model exists; it is based entirely on results from the parent OGCM. Degradation was made horizontally over sets of four adjacent grid-cell squares for each vertical layer of the parent model. However, final resolution did not suffer because as a second step, after allowing the degraded model to reach equilibrium, we used its tracer output to reinitialize the parent model (at the original resolution). After reinitialization, the parent model must then be integrated only to a few hundred years before reaching equilibrium. To validate our degradation-integration technique (DEGINT), we compared {sup 14}C results from runs with and without this approach. Differences are less than 10 permille throughout 98.5% of the ocean volume. Predicted natural {sup 14}C appears reasonable over most of the ocean. In the Atlantic, modeled {Delta}{sup 14}C indicates that as observed, the North Atlantic Deep Water (NADW) fills the deep North Atlantic, and Antartic Intermediate Water (AAIW) infiltrates northward. (orig.) With 12 figs., 1 tab., 42 refs.

A study of enhanced performance of VUV/UV process for the degradation of micropollutants from contaminated water

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Mehdi; Mohseni, Madjid, E-mail: madjid.mohseni@ubc.ca

2015-08-30

Highlights: • Developing a comprehensive CFD simulation tool for VUV/UV photoreactors modeling. • Analysing impact of reactor hydrodynamics on the AOP performance of VUV/UV process. • Cutting the energy cost of VUV/UV process by means of improved-photoreactor design. • Experimentally verifying the CFD results using a VUV/UV prototype photoreactor. - Abstract: VUV/UV is a chemical-free and straightforward solution for the degradation of emerging contaminants from water sources. The objective of this work was to investigate the feasibility of VUV/UV advanced oxidation process for the effective degradation of a target micropollutant, atrazine, under continuous flow operation of 0.5–6.5 L/min. To provide an in-depth understanding of process, a comprehensive computational fluid dynamics (CFD) model, incorporating flow hydrodynamics, 185 nm VUV and 254 nm UV radiation propagation along with a complete kinetic scheme, was developed and validated experimentally. The experimental degradation rates and CFD predicted values showed great consistency with less than 2.9% average absolute relative deviation (AARD). Utilizing the verified model, energy-efficiency of the VUV/UV process under a wide range of reactor configurations was assessed in terms of electrical energy-per-order (EEO), ·OH concentration as well as delivered UV and VUV dose distributions. Thereby, the extent of mixing and circulation zones was found as key parameter controlling the treatment economy and energy-efficiency of the VUV/UV process. Utilizing a CFD-driven baffle design strategy, an improved VUV/UV process with up to 72% reduction in the total electrical energy requirement of atrazine degradation was introduced and verified experimentally.

A New Environmentally Safe Formulation and of Low Cost for Prolonged Release System of Atrazine and Diuron

Directory of Open Access Journals (Sweden)

Gracy karla da Rocha Cortes

2017-07-01

Full Text Available Diuron and atrazine were incorporated in new formulations developed with the purpose to improve herbicides action through release systems, as well as to reduce the environmental toxicity. A low cost formulation (ALG/ESC was obtained by combining sodium alginate (ALG with fish scales of the Piau fish (ESC from the Leporinus elongatus species. From the crosslinking of ALG/ESC with CaCl2, the formulation ALG/ESC-CaCl2 was obtained. For ALG/ESC-CaCl2, the results are successful, showing a prolonged release of 3.5 and 4.5 days for atrazine and diuron, respectively. Based on parameters of an empirical equation used to fit the herbicide release data, it appears that the release systems of diuron and atrazine from ALG/ESC-CaCl2 are by diffusion processes due to anomalous transport, which did not follow Fick’s laws of diffusion. DOI: http://dx.doi.org/10.17807/orbital.v9i3.994

Reversible electrokinetic adsorption barriers for the removal of atrazine and oxyfluorfen from spiked soils.

Science.gov (United States)

Vieira Dos Santos, E; Sáez, C; Cañizares, P; Martínez-Huitle, C A; Rodrigo, M A

2017-01-15

This study demonstrates the application of reversible electrokinetic adsorption barrier (REKAB) technology to soils spiked with low-solubility pollutants. A permeable reactive barrier (PRB) of granular activated carbon (GAC) was placed between the anode and cathode of an electrokinetic (EK) soil remediation bench-scale setup with the aim of enhancing the removal of two low-solubility herbicides (atrazine and oxyfluorfen) using a surfactant solution (sodium dodecyl sulfate) as the flushing fluid. This innovative study focused on evaluating the interaction between the EK system and the GAC-PRB, attempting to obtain insights into the primary mechanisms involved. The obtained results highlighted the successful treatment of atrazine and oxyfluorfen in contaminated soils. The results obtained from the tests after 15days of treatment were compared with those obtained using the more conventional electrokinetic soil flushing (EKSF) technology, and very important differences were observed. Although both technologies are efficient for removing the herbicides from soils, REKAB outperforms EKSF. After the 15-day treatment tests, only approximately 10% of atrazine and oxyfluorfen remained in the soil, and adsorption onto the GAC bed was an important removal mechanism (15-17% of herbicide retained). The evaporation loses in REKAB were lower than those obtained in EKSF (45-50% compared to 60-65%). Copyright © 2016 Elsevier B.V. All rights reserved.

A collection of cytochrome P450 monooxygenase genes involved in modification and detoxification of herbicide atrazine in rice (Oryza sativa) plants.

Science.gov (United States)

Rong Tan, Li; Chen Lu, Yi; Jing Zhang, Jing; Luo, Fang; Yang, Hong

2015-09-01

Plant cytochrome P450 monooxygenases constitute one of the largest families of protein genes involved in plant growth, development and acclimation to biotic and abiotic stresses. However, whether these genes respond to organic toxic compounds and their biological functions for detoxifying toxic compounds such as herbicides in rice are poorly understood. The present study identified 201 genes encoding cytochrome P450s from an atrazine-exposed rice transcriptome through high-throughput sequencing. Of these, 69 cytochrome P450 genes were validated by microarray and some of them were confirmed by real time PCR. Activities of NADPH-cytochrome P450 reductase (CPR) and p-nitroanisole O-demethylase (PNOD) related to toxicity were determined and significantly induced by atrazine exposure. To dissect the mechanism underlying atrazine modification and detoxification by P450, metabolites (or derivatives) of atrazine in plants were analyzed by ultra performance liquid chromatography mass spectrometry (UPLC/MS). Major metabolites comprised desmethylatrazine (DMA), desethylatrazine (DEA), desisopropylatrazine (DIA), hydroxyatrazine (HA), hydroxyethylatrazine (HEA) and hydroxyisopropylatrazine (HIA). All of them were chemically modified by P450s. Furthermore, two specific inhibitors of piperonyl butoxide (PBO) and malathion (MAL) were used to assess the correlation between the P450s activity and rice responses including accumulation of atrazine in tissues, shoot and root growth and detoxification. Copyright © 2015 Elsevier Inc. All rights reserved.

Dissolved nutrients and atrazine removal by column-scale monophasic and biphasic rain garden model systems.

Science.gov (United States)

Yang, Hanbae; McCoy, Edward L; Grewal, Parwinder S; Dick, Warren A

2010-08-01

Rain gardens are bioretention systems that have the potential to reduce peak runoff flow and improve water quality in a natural and aesthetically pleasing manner. We compared hydraulic performance and removal efficiencies of nutrients and atrazine in a monophasic rain garden design versus a biphasic design at a column-scale using simulated runoff. The biphasic rain garden was designed to increase retention time and removal efficiency of runoff pollutants by creating a sequence of water saturated to unsaturated conditions. We also evaluated the effect of C substrate availability on pollutant removal efficiency in the biphasic rain garden. Five simulated runoff events with various concentrations of runoff pollutants (i.e. nitrate, phosphate, and atrazine) were applied to the monophasic and biphasic rain gardens once every 5d. Hydraulic performance was consistent over the five simulated runoff events. Peak flow was reduced by approximately 56% for the monophasic design and 80% for the biphasic design. Both rain garden systems showed excellent removal efficiency of phosphate (89-100%) and atrazine (84-100%). However, significantly (prain garden (29-39%). Addition of C substrate in the form of glucose increased removal efficiency of nitrate significantly (prain gardens. (c) 2010 Elsevier Ltd. All rights reserved.

Variation in the response of the invasive species Potamopyrgus antipodarum (Smith) to natural (cyanobacterial toxin) and anthropogenic (herbicide atrazine) stressors

International Nuclear Information System (INIS)

Gerard, Claudia; Poullain, Virginie

2005-01-01

In the context of increasing freshwater pollution, the impact on life-traits (survival, growth and fecundity) and locomotion of Potamopyrgus antipodarum of a 5-week field-concentration exposure to the cyanobacterial toxin microcystin-LR and the triazine herbicide, atrazine was studied. Whatever the age of exposed snails (juveniles, subadults, adults), microcystin-LR induced a decrease in survival, growth and fecundity but had no effect on locomotion. Atrazine induced a decrease in locomotory activity but had no significant effect on the life-traits. These results are discussed in terms of consequences to field populations. - At concentrations relevant to the field, cyanobacterial toxins (natural) and atrazine (anthropogenic) are detrimental to the gastropod Potamopyrgus antipodarum, with a greater toxicity for the natural (vs anthropogenic) stressor

Variation in the response of the invasive species Potamopyrgus antipodarum (Smith) to natural (cyanobacterial toxin) and anthropogenic (herbicide atrazine) stressors

Energy Technology Data Exchange (ETDEWEB)

Gerard, Claudia [UMR CNRS Ecobio 6553, Equipe Physiologie et Ecophysiologie, Universite de Rennes 1, Avenue du General Leclerc, 35042 Rennes cedex (France)]. E-mail: claudia.gerard@univ-rennes1.fr; Poullain, Virginie [UMR CNRS Ecobio 6553, Equipe Physiologie et Ecophysiologie, Universite de Rennes 1, Avenue du General Leclerc, 35042 Rennes cedex (France)

2005-11-15

In the context of increasing freshwater pollution, the impact on life-traits (survival, growth and fecundity) and locomotion of Potamopyrgus antipodarum of a 5-week field-concentration exposure to the cyanobacterial toxin microcystin-LR and the triazine herbicide, atrazine was studied. Whatever the age of exposed snails (juveniles, subadults, adults), microcystin-LR induced a decrease in survival, growth and fecundity but had no effect on locomotion. Atrazine induced a decrease in locomotory activity but had no significant effect on the life-traits. These results are discussed in terms of consequences to field populations. - At concentrations relevant to the field, cyanobacterial toxins (natural) and atrazine (anthropogenic) are detrimental to the gastropod Potamopyrgus antipodarum, with a greater toxicity for the natural (vs anthropogenic) stressor.

Effect of 2,4-D and atrazine when applied with glyphosate ripener

Science.gov (United States)

Management of late-season morningglory infestations in sugarcane is accomplished with aerial applications of the postemergence herbicides 2,4-D, dicamba, or atrazine. Likewise, the aerial application of glyphosate prior to harvest to improve stalk sucrose levels is a common practice for many Louisia...

Decomposition of atrazine traces in water by combination of non-thermal electrical discharge and adsorption on nanofiber membrane.

Science.gov (United States)

Vanraes, Patrick; Willems, Gert; Daels, Nele; Van Hulle, Stijn W H; De Clerck, Karen; Surmont, Pieter; Lynen, Frederic; Vandamme, Jeroen; Van Durme, Jim; Nikiforov, Anton; Leys, Christophe

2015-04-01

In recent decades, several types of persistent substances are detected in the aquatic environment at very low concentrations. Unfortunately, conventional water treatment processes are not able to remove these micropollutants. As such, advanced treatment methods are required to meet both current and anticipated maximally allowed concentrations. Plasma discharge in contact with water is a promising new technology, since it produces a wide spectrum of oxidizing species. In this study, a new type of reactor is tested, in which decomposition by atmospheric pulsed direct barrier discharge (pDBD) plasma is combined with micropollutant adsorption on a nanofiber polyamide membrane. Atrazine is chosen as model micropollutant with an initial concentration of 30 μg/L. While the H2O2 and O3 production in the reactor is not influenced by the presence of the membrane, there is a significant increase in atrazine decomposition when the membrane is added. With membrane, 85% atrazine removal can be obtained in comparison to only 61% removal without membrane, at the same experimental parameters. The by-products of atrazine decomposition identified by HPLC-MS are deethylatrazine and ammelide. Formation of these by-products is more pronounced when the membrane is added. These results indicate the synergetic effect of plasma discharge and pollutant adsorption, which is attractive for future applications of water treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Drinking-water exposure to a mixture of nitrate and low-dose atrazine metabolites and small-for-gestational age (SGA) babies: a historic cohort study.

Science.gov (United States)

Migeot, V; Albouy-Llaty, M; Carles, C; Limousi, F; Strezlec, S; Dupuis, A; Rabouan, S

2013-04-01

Groundwater, surface water and drinking water are contaminated by nitrates and atrazine, an herbicide. They are present as a mixture in drinking water and with their endocrine-disrupting activity, they may alter fetal growth. To study an association between drinking-water atrazine metabolites/nitrate mixture exposure and small-for-gestational-age(SGA). A historic cohort study based on birth records and drinking-water nitrate and pesticide measurements in Deux-Sèvres (France) between 2005 and 2009 was carried out. Exposure to drinking-water atrazine metabolites/nitrate mixture was divided into 6 classes according to the presence or absence of atrazine metabolites and to terciles of nitrate concentrations in each trimester of pregnancy. Regression analysis of SGA by mixture exposure at second trimester was subsequently conducted. We included 11,446 woman-neonate couples of whom 37.0% were exposed to pesticides, while 99.9% of the women were exposed to nitrates. Average nitrate concentration was from 0 to 63.30 mg/L. In the second trimester of pregnancy, the risk of SGA was different with mixture exposure when drinking-water atrazine metabolites, mainly 2 hydroxyatrazine and desethylatrazine, were present and nitrate dose exposure increased: compared to single first tercile of nitrate concentration exposure, single second tercile exposure OR was 1.74 CI 95% [1.10; 2.75] and atrazine metabolites presence in the third tercile of nitrate concentration exposure OR was 0.87 CI 95% [0.45;1.67]. It is possible that the association found at the second trimester of exposure with regard to birth weight may likewise be observed before birth, with regard to the estimated fetal weight, and that it might change in the event that the atrazine metabolites dose were higher or the nitrate dose lower. It would appear necessary to further explore the variability of effects. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

Aging precursors and degradation effects of SiC-MOSFET modules under highly accelerated power cycling conditions

DEFF Research Database (Denmark)

Luo, Haoze; Iannuzzo, Francesco; Blaabjerg, Frede

2017-01-01

A highly accelerated power cycling test platform using current source converter for SiC-MOSFET power modules is proposed. The control principles of delta and average junction temperatures are introduced. By using isolated thermal fibers, the junction temperature (Tj) variations can be monitored...... and compared. As a result, the effects of degradation on the static and dynamic characteristics during conventional operation are discussed. Finally, the research results can help examine the failure precursors and then estimate the remaining useful lifetime of SiC MOSFET modules....

Exposure to atrazine affects the expression of key genes in metabolic pathways integral to energy homeostasis in Xenopus laevis tadpoles

International Nuclear Information System (INIS)

Zaya, Renee M.; Amini, Zakariya; Whitaker, Ashley S.; Ide, Charles F.

2011-01-01

In our laboratory, Xenopus laevis tadpoles exposed throughout development to 200 or 400 μg/L atrazine, concentrations reported to periodically occur in puddles, vernal ponds and runoff soon after application, were smaller and had smaller fat bodies (the tadpole's lipid storage organ) than controls. It was hypothesized that these changes were due to atrazine-related perturbations of energy homeostasis. To investigate this hypothesis, selected metabolic responses to exposure at the transcriptional and biochemical levels in atrazine-exposed tadpoles were measured. DNA microarray technology was used to determine which metabolic pathways were affected after developmental exposure to 400 μg/L atrazine. From these data, genes representative of the affected pathways were selected for assay using quantitative real time polymerase chain reaction (qRT-PCR) to measure changes in expression during a 2-week exposure to 400 μg/L. Finally, ATP levels were measured from tadpoles both early in and at termination of exposure to 200 and 400 μg/L. Microarray analysis revealed significant differential gene expression in metabolic pathways involved with energy homeostasis. Pathways with increased transcription were associated with the conversion of lipids and proteins into energy. Pathways with decreased transcription were associated with carbohydrate metabolism, fat storage, and protein synthesis. Using qRT-PCR, changes in gene expression indicative of an early stress response to atrazine were noted. Exposed tadpoles had significant decreases in acyl-CoA dehydrogenase (AD) and glucocorticoid receptor protein (GR) mRNA after 24 h of exposure, and near-significant (p = 0.07) increases in peroxisome proliferator-activated receptor β (PPAR-β) mRNA by 72 h. Decreases in AD suggested decreases in fatty acid β-oxidation while decreases in GR may have been a receptor desensitization response to a glucocorticoid surge. Involvement of PPAR-β, an energy homeostasis regulatory molecule

Exposure to atrazine affects the expression of key genes in metabolic pathways integral to energy homeostasis in Xenopus laevis tadpoles

Energy Technology Data Exchange (ETDEWEB)

Zaya, Renee M., E-mail: renee.zaya@wmich.edu [Great Lakes Environmental and Molecular Sciences Center, Department of Biological Sciences, 3425 Wood Hall, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (United States); Amini, Zakariya, E-mail: zakariya.amini@wmich.edu [Great Lakes Environmental and Molecular Sciences Center, Department of Biological Sciences, 3425 Wood Hall, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (United States); Whitaker, Ashley S., E-mail: ashley.s.whitaker@wmich.edu [Great Lakes Environmental and Molecular Sciences Center, Department of Biological Sciences, 3425 Wood Hall, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (United States); Ide, Charles F., E-mail: charles.ide@wmich.edu [Great Lakes Environmental and Molecular Sciences Center, Department of Biological Sciences, 3425 Wood Hall, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (United States)

2011-08-15

In our laboratory, Xenopus laevis tadpoles exposed throughout development to 200 or 400 {mu}g/L atrazine, concentrations reported to periodically occur in puddles, vernal ponds and runoff soon after application, were smaller and had smaller fat bodies (the tadpole's lipid storage organ) than controls. It was hypothesized that these changes were due to atrazine-related perturbations of energy homeostasis. To investigate this hypothesis, selected metabolic responses to exposure at the transcriptional and biochemical levels in atrazine-exposed tadpoles were measured. DNA microarray technology was used to determine which metabolic pathways were affected after developmental exposure to 400 {mu}g/L atrazine. From these data, genes representative of the affected pathways were selected for assay using quantitative real time polymerase chain reaction (qRT-PCR) to measure changes in expression during a 2-week exposure to 400 {mu}g/L. Finally, ATP levels were measured from tadpoles both early in and at termination of exposure to 200 and 400 {mu}g/L. Microarray analysis revealed significant differential gene expression in metabolic pathways involved with energy homeostasis. Pathways with increased transcription were associated with the conversion of lipids and proteins into energy. Pathways with decreased transcription were associated with carbohydrate metabolism, fat storage, and protein synthesis. Using qRT-PCR, changes in gene expression indicative of an early stress response to atrazine were noted. Exposed tadpoles had significant decreases in acyl-CoA dehydrogenase (AD) and glucocorticoid receptor protein (GR) mRNA after 24 h of exposure, and near-significant (p = 0.07) increases in peroxisome proliferator-activated receptor {beta} (PPAR-{beta}) mRNA by 72 h. Decreases in AD suggested decreases in fatty acid {beta}-oxidation while decreases in GR may have been a receptor desensitization response to a glucocorticoid surge. Involvement of PPAR-{beta}, an energy

Banana peel as an adsorbent for removing atrazine and ametryne from waters.

Science.gov (United States)

Silva, Claudineia R; Gomes, Taciana F; Andrade, Graziela C R M; Monteiro, Sergio H; Dias, Ana C R; Zagatto, Elias A G; Tornisielo, Valdemar L

2013-03-13

The feasibility of using banana peel for removal of the pesticides atrazine and ametryne from river and treated waters has been demonstrated, allowing the design of an efficient, fast, and low-cost strategy for remediation of polluted waters. The conditions for removal of these pesticides in a laboratory scale were optimized as sample volume = 50 mL, banana mass = 3.0 g, stirring time = 40 min, and no pH adjustment necessary. KF(sor) values for atrazine and ametryne were evaluated as 35.8 and 54.1 μg g(-1) (μL mL(-1)) by using liquid scintillation spectrometry. Adsorption was also evaluated by LC-ESI-MS/MS. As quantification limits were 0.10 and 0.14 μg L(-1) for both pesticides, sample preconcentration was not needed. Linear analytical curves (up to 10 μg L(-1)), precise results (RSD 90% removal efficiency were attained for both pesticides. Water samples collected near an intensively cultivated area were adequately remedied.

Phytotoxicity of atrazine, isoproturon, and diuron to submersed macrophytes in outdoor mesocosms.

Science.gov (United States)

Knauert, Stefanie; Singer, Heinz; Hollender, Juliane; Knauer, Katja

2010-01-01

The submersed macrophytes Elodea canadensis, Myriophyllum spicatum and Potamogeton lucens were constantly exposed over a five-week period to environmentally relevant concentrations of atrazine, isoproturon, diuron, and their mixture in outdoor mesocosms. Effects were evaluated investigating photosynthetic efficiency (PE) of the three macrophytes and growth of M. spicatum and E. canadensis. Adverse effects on PE were observed on days 2 and 5 after application. M. spicatum was found to be the more sensitive macrophyte. E. canadensis and P. lucens were less sensitive to atrazine, diuron and the mixture and insensitive to isoproturon. PE of M. spicatum was similarly affected by the single herbicides and the mixture demonstrating concentration addition. Growth of E. canadensis and M. spicatum was not reduced indicating that herbicide exposure did not impair plant development. Although PE measurements turned out to be a sensitive method to monitor PSII herbicides, plant growth remains the more relevant ecological endpoint in risk assessment.

Comparative Cytotoxicity of the Herbicide Atrazine to Four Inbred Maize Lines (Zea mays L.)

International Nuclear Information System (INIS)

Shehata, Afaf I; AlGhethar, Haila A; AlHomaidan, Ali A; Arif, Ibrahim A

2008-01-01

Atrazine is one of the most widely used herbicides in the world. Recent reports have indicated that it has adverse impacts on the endocrine systems and on the early developments of wild animals and it has been banned in many European countries including Switzerland, the home of the manufacturing company. The genotoxic effects of Atrazine on four inbred lines of maize (Zea mays L.) were investigated. The herbicide showed mitoinhibition and clastogenic effects on the mitotic index of maize lines and they were proportional to the concentrations and time. The frequency of abnormality, chromosomal breakage, stickiness, lagging, C-metaphase and C-anaphase were observed at different stages of mitosis in treated cells. The harmful effect of this environmental pollutant proved that it may act as a strong mutagen. (author)

A Bayesian reliability evaluation method with integrated accelerated degradation testing and field information

International Nuclear Information System (INIS)

Wang, Lizhi; Pan, Rong; Li, Xiaoyang; Jiang, Tongmin

2013-01-01

Accelerated degradation testing (ADT) is a common approach in reliability prediction, especially for products with high reliability. However, oftentimes the laboratory condition of ADT is different from the field condition; thus, to predict field failure, one need to calibrate the prediction made by using ADT data. In this paper a Bayesian evaluation method is proposed to integrate the ADT data from laboratory with the failure data from field. Calibration factors are introduced to calibrate the difference between the lab and the field conditions so as to predict a product's actual field reliability more accurately. The information fusion and statistical inference procedure are carried out through a Bayesian approach and Markov chain Monte Carlo methods. The proposed method is demonstrated by two examples and the sensitivity analysis to prior distribution assumption

An improved high-performance liquid chromatography-tandem mass spectrometric method to measure atrazine and its metabolites in human urine.

Science.gov (United States)

Panuwet, Parinya; Restrepo, Paula A; Magsumbol, Melina; Jung, Kyung Y; Montesano, M Angela; Needham, Larry L; Barr, Dana Boyd

2010-04-15

We report an improved solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry method with isotope dilution quantification to measure seven atrazine metabolites in urine. The metabolites measured were hydroxyatrazine (HA), diaminochloroatrazine (DACT), desisopropylatrazine (DIA), desethylatrazine (DEA), desethylatrazine mercapturate (DEAM), atrazine mercapturate (ATZM), and atrazine (ATZ). Using offline mixed-mode reversed-phase/cation-exchange solid-phase extraction dramatically increased recovery and sensitivity by reducing the influence of matrix components during separation and analysis. DACT extraction recovery improved to greater than 80% while the other analytes had similar extraction efficiencies as previously observed. Limits of detection were lower than our previous method (0.05-0.19 ng/mL) with relative standard deviations less than 10%. The total runtime was shorter (18 min) than the previous on-line method, thus it is suitable for large-scale sample analyses. We increased the throughput of our method twofold by using the newer extraction technique. Published by Elsevier B.V.

Exposure to atrazine affects the expression of key genes in metabolic pathways integral to energy homeostasis in Xenopus laevis tadpoles.

Science.gov (United States)

Zaya, Renee M; Amini, Zakariya; Whitaker, Ashley S; Ide, Charles F

2011-08-01

In our laboratory, Xenopus laevis tadpoles exposed throughout development to 200 or 400 μg/L atrazine, concentrations reported to periodically occur in puddles, vernal ponds and runoff soon after application, were smaller and had smaller fat bodies (the tadpole's lipid storage organ) than controls. It was hypothesized that these changes were due to atrazine-related perturbations of energy homeostasis. To investigate this hypothesis, selected metabolic responses to exposure at the transcriptional and biochemical levels in atrazine-exposed tadpoles were measured. DNA microarray technology was used to determine which metabolic pathways were affected after developmental exposure to 400 μg/L atrazine. From these data, genes representative of the affected pathways were selected for assay using quantitative real time polymerase chain reaction (qRT-PCR) to measure changes in expression during a 2-week exposure to 400 μg/L. Finally, ATP levels were measured from tadpoles both early in and at termination of exposure to 200 and 400 μg/L. Microarray analysis revealed significant differential gene expression in metabolic pathways involved with energy homeostasis. Pathways with increased transcription were associated with the conversion of lipids and proteins into energy. Pathways with decreased transcription were associated with carbohydrate metabolism, fat storage, and protein synthesis. Using qRT-PCR, changes in gene expression indicative of an early stress response to atrazine were noted. Exposed tadpoles had significant decreases in acyl-CoA dehydrogenase (AD) and glucocorticoid receptor protein (GR) mRNA after 24 h of exposure, and near-significant (p=0.07) increases in peroxisome proliferator-activated receptor β (PPAR-β) mRNA by 72 h. Decreases in AD suggested decreases in fatty acid β-oxidation while decreases in GR may have been a receptor desensitization response to a glucocorticoid surge. Involvement of PPAR-β, an energy homeostasis regulatory molecule, also

Accelerated stability testing of organic photovoltaics using concentrated sunlight

DEFF Research Database (Denmark)

Katz, Eugene A.; Manor, Assaf; Mescheloff, Asaf

2012-01-01

We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported.......We suggest to use concentrated sunlight for accelerated studies of light-induced mechanisms in the degradation of organic photovoltaics (OPV) based on the polymer (P3HT)/fullerene (PCBM) bulk heterojunctions. Two particular cases of the degradation are reported....

Phytotoxicity of atrazine, isoproturon, and diuron to submersed macrophytes in outdoor mesocosms

International Nuclear Information System (INIS)

Knauert, Stefanie; Singer, Heinz; Hollender, Juliane; Knauer, Katja

2010-01-01

The submersed macrophytes Elodea canadensis, Myriophyllum spicatum and Potamogeton lucens were constantly exposed over a five-week period to environmentally relevant concentrations of atrazine, isoproturon, diuron, and their mixture in outdoor mesocosms. Effects were evaluated investigating photosynthetic efficiency (PE) of the three macrophytes and growth of M. spicatum and E. canadensis. Adverse effects on PE were observed on days 2 and 5 after application. M. spicatum was found to be the more sensitive macrophyte. E. canadensis and P. lucens were less sensitive to atrazine, diuron and the mixture and insensitive to isoproturon. PE of M. spicatum was similarly affected by the single herbicides and the mixture demonstrating concentration addition. Growth of E. canadensis and M. spicatum was not reduced indicating that herbicide exposure did not impair plant development. Although PE measurements turned out to be a sensitive method to monitor PSII herbicides, plant growth remains the more relevant ecological endpoint in risk assessment. - Short-term effects on photosynthesis did not result in growth reduction of submerse macrophytes exposed to PSII inhibitors.

Phytotoxicity of atrazine, isoproturon, and diuron to submersed macrophytes in outdoor mesocosms

Energy Technology Data Exchange (ETDEWEB)

Knauert, Stefanie, E-mail: stefanie.knauert@basf.co [University of Basel, Department of Environmental Sciences, Hebelstrasse 1, 4056 Basel (Switzerland); Singer, Heinz; Hollender, Juliane [Eawag: Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Chemistry, Uberlandstrasse 133, 8600 Duebendorf (Switzerland); Knauer, Katja [University of Basel, Program Sustainability Research, Klingelbergstr. 50, 4056 Basel (Switzerland)

2010-01-15

The submersed macrophytes Elodea canadensis, Myriophyllum spicatum and Potamogeton lucens were constantly exposed over a five-week period to environmentally relevant concentrations of atrazine, isoproturon, diuron, and their mixture in outdoor mesocosms. Effects were evaluated investigating photosynthetic efficiency (PE) of the three macrophytes and growth of M. spicatum and E. canadensis. Adverse effects on PE were observed on days 2 and 5 after application. M. spicatum was found to be the more sensitive macrophyte. E. canadensis and P. lucens were less sensitive to atrazine, diuron and the mixture and insensitive to isoproturon. PE of M. spicatum was similarly affected by the single herbicides and the mixture demonstrating concentration addition. Growth of E. canadensis and M. spicatum was not reduced indicating that herbicide exposure did not impair plant development. Although PE measurements turned out to be a sensitive method to monitor PSII herbicides, plant growth remains the more relevant ecological endpoint in risk assessment. - Short-term effects on photosynthesis did not result in growth reduction of submerse macrophytes exposed to PSII inhibitors.

Developmental toxicity of two common corn pesticides to the endangered southern bell frog (Litoria raniformis)

International Nuclear Information System (INIS)

Choung, Catherine B.; Hyne, Ross V.; Mann, Reinier M.; Stevens, Mark M.; Hose, Grant C.

2011-01-01

To examine the link between corn agriculture and the observed decline of the endangered southern bell frog (SBF), the effects of two corn crop pesticides on larval growth and development were investigated. Tadpoles were exposed to terbufos sulfone (10 μg/L), a major breakdown product of the insecticide terbufos, and the herbicide atrazine (25 μg/L) individually and as a mixture until the completion of metamorphosis. Atrazine did not interact synergistically with terbufos sulfone or result in significant effects on growth and development alone, although there was some indication of accelerated metamorphosis in the pilot study. Terbufos sulfone alone and as a mixture (terbufos/atrazine) significantly slowed larval development and ultimately delayed metamorphosis. The observed developmental effects from an environmentally relevant concentration of terbufos sulfone indicates a risk posed by this persistent degradation product to the endangered SBF, which breeds and develops in the rice bays adjacent to corn fields treated with pesticides. - Highlights: → The effect of terbufos sulfone and atrazine on larval growth and development was investigated. → Terbufos sulfone alone significantly slowed development and delayed metamorphosis of tadpoles. → Atrazine had no observable effects alone nor did it interact synergistically with terbufos sulfone. → The developmental effects indicates a risk to endangered southern bell frogs in the irrigation area. → The results highlight the toxicological importance of some pesticide breakdown products. - A breakdown product of the insecticide terbufos retards development and delays metamorphosis of southern bell frog tadpoles.

Developmental toxicity of two common corn pesticides to the endangered southern bell frog (Litoria raniformis)

Energy Technology Data Exchange (ETDEWEB)

Choung, Catherine B., E-mail: Catherine.Choung@mq.edu.au [Department of Biological Sciences, Macquarie University, Sydney, NSW 2109 (Australia); Hyne, Ross V. [Ecotoxicology and Environmental Contaminants Section, Office of Environment and Heritage, PO Box 29, Lidcombe, NSW 1825 (Australia); Mann, Reinier M. [Centre for Environmental Sustainability, University of Technology - Sydney, PO Box 123, Broadway, NSW 2007 (Australia); Stevens, Mark M. [EH Graham Centre for Agricultural Innovation (Industry and Investment NSW and Charles Sturt University), Yanco Agricultural Institute, Private Mail Bag, Yanco, NSW 2703 (Australia); Hose, Grant C. [Department of Biological Sciences, Macquarie University, Sydney, NSW 2109 (Australia)

2011-10-15

To examine the link between corn agriculture and the observed decline of the endangered southern bell frog (SBF), the effects of two corn crop pesticides on larval growth and development were investigated. Tadpoles were exposed to terbufos sulfone (10 {mu}g/L), a major breakdown product of the insecticide terbufos, and the herbicide atrazine (25 {mu}g/L) individually and as a mixture until the completion of metamorphosis. Atrazine did not interact synergistically with terbufos sulfone or result in significant effects on growth and development alone, although there was some indication of accelerated metamorphosis in the pilot study. Terbufos sulfone alone and as a mixture (terbufos/atrazine) significantly slowed larval development and ultimately delayed metamorphosis. The observed developmental effects from an environmentally relevant concentration of terbufos sulfone indicates a risk posed by this persistent degradation product to the endangered SBF, which breeds and develops in the rice bays adjacent to corn fields treated with pesticides. - Highlights: > The effect of terbufos sulfone and atrazine on larval growth and development was investigated. > Terbufos sulfone alone significantly slowed development and delayed metamorphosis of tadpoles. > Atrazine had no observable effects alone nor did it interact synergistically with terbufos sulfone. > The developmental effects indicates a risk to endangered southern bell frogs in the irrigation area. > The results highlight the toxicological importance of some pesticide breakdown products. - A breakdown product of the insecticide terbufos retards development and delays metamorphosis of southern bell frog tadpoles.

Hydrologic and atrazine simulation of the Cedar Creek Watershed using the SWAT model.

Science.gov (United States)

Larose, M; Heathman, G C; Norton, L D; Engel, B

2007-01-01

One of the major factors contributing to surface water contamination in agricultural areas is the use of pesticides. The Soil and Water Assessment Tool (SWAT) is a hydrologic model capable of simulating the fate and transport of pesticides in an agricultural watershed. The SWAT model was used in this study to estimate stream flow and atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) losses to surface water in the Cedar Creek Watershed (CCW) within the St. Joseph River Basin in northeastern Indiana. Model calibration and validation periods consisted of five and two year periods, respectively. The National Agricultural Statistics Survey (NASS) 2001 land cover classification and the Soil Survey Geographic (SSURGO) database were used as model input data layers. Data from the St. Joseph River Watershed Initiative and the Soil and Water Conservation Districts of Allen, Dekalb, and Noble counties were used to represent agricultural practices in the watershed which included the type of crops grown, tillage practices, fertilizer, and pesticide application rates. Model results were evaluated based on efficiency coefficient values, standard statistical measures, and visual inspection of the measured and simulated hydrographs. The Nash and Sutcliffe model efficiency coefficients (E(NS)) for monthly and daily stream flow calibration and validation ranged from 0.51 to 0.66. The E(NS) values for atrazine calibration and validation ranged from 0.43 to 0.59. All E(NS) values were within the range of acceptable model performance standards. The results of this study indicate that the model is an effective tool in capturing the dynamics of stream flow and atrazine concentrations on a large-scale agricultural watershed in the midwestern USA.

Halide salts accelerate degradation of high explosives by zerovalent iron

International Nuclear Information System (INIS)

Kim, Jong Sung; Shea, Patrick J.; Yang, Jae E.; Kim, Jang-Eok

2007-01-01

Zerovalent iron (Fe 0 , ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe 0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl - and Br - was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br - was present in solution. - The addition of halide ions promotes the degradation of high explosives by zerovalent iron

Accelerated reliability demonstration under competing failure modes

International Nuclear Information System (INIS)

Luo, Wei; Zhang, Chun-hua; Chen, Xun; Tan, Yuan-yuan

2015-01-01

The conventional reliability demonstration tests are difficult to apply to products with competing failure modes due to the complexity of the lifetime models. This paper develops a testing methodology based on the reliability target allocation for reliability demonstration under competing failure modes at accelerated conditions. The specified reliability at mission time and the risk caused by sampling of the reliability target for products are allocated for each failure mode. The risk caused by degradation measurement fitting of the target for a product involving performance degradation is equally allocated to each degradation failure mode. According to the allocated targets, the accelerated life reliability demonstration test (ALRDT) plans for the failure modes are designed. The accelerated degradation reliability demonstration test plans and the associated ALRDT plans for the degradation failure modes are also designed. Next, the test plan and the decision rules for the products are designed. Additionally, the effects of the discreteness of sample size and accepted number of failures for failure modes on the actual risks caused by sampling for the products are investigated. - Highlights: • Accelerated reliability demonstration under competing failure modes is studied. • The method is based on the reliability target allocation involving the risks. • The test plan for the products is based on the plans for all the failure modes. • Both failure mode and degradation failure modes are considered. • The error of actual risks caused by sampling for the products is small enough

Effects of chronic low concentrations of pesticides chlorpyrifos and atrazine in indoor freshwater microcosms.

NARCIS (Netherlands)

Brink, van den P.J.; Donk, van E.; Gylstra, R.; Crum, S.J.H.; Brock, T.C.M.

1995-01-01

Standards for pesticide concentrations in water are based on the laboratory toxicity of the most susceptible standard test organisms (algae, crustaceans or fish). Field studies have shown that the standards for the insecticide chlorpyrifos and the herbicide atrazine will protect aquatic ecosystems

Effects of an atrazine, metolachlor and fipronil mixture on Hyalella azteca (Saussure) in a modified backwater wetland.

Science.gov (United States)

Lizotte, Richard E; Knight, Scott S; Shields, F Douglas; Bryant, Charles T

2009-12-01

We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a pesticide mixture of atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first 2 h of amendment at the upstream amendment site but not at any time at the downstream site. H. azteca survival varied spatially and temporally in conjunction with measured pesticide mixture concentrations. Hyalella azteca 96 h survival pesticide mixture effects concentrations ranges were 10.214–11.997, 5.822–6.658, 0.650–0.817, and 0.030–0.048 μg L−1 for atrazine, metolachlor, fipronil, and fipronil-sulfone, respectively.

DEGRADAÇÃO FOTOCATALÍTICA DE ATRAZINA NA PRESENÇA DE CATALISADORES NANOPARTICULADOS

Directory of Open Access Journals (Sweden)

Flávio Arantes Campos

Full Text Available Atrazine is a persistent herbicide and several studies have detected their presence in drinking water sources. In this work the atrazine photocatalytic degradation was investigated in aqueous solution using TiO2, ZnO and TiO2/ZnO catalysts. The catalysts were synthesized by Pechini's method and characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM. The process was monitored using absorption spectroscopy in ultraviolet and visible (UV-vis region and high performance liquid chromatography (HPLC. The prepared catalysts were used in ultrafine powder form and its characterization showed nanometer order particle sizes. The atrazine absorbance decrease was observed after samples irradiation in catalysts presence and HPLC analysis showed a significant herbicide reduction and other compounds formation as degradation products. The ZnO catalyst use was more effective in atrazine molecule degradation compared to the other nanoparticles.

The potential applications of using compost chars for removing the hydrophobic herbicide atrazine from solution.

Science.gov (United States)

Tsui, Lo; Roy, William R

2008-09-01

One commercial compost sample was pyrolyzed to produce chars as a sorbent for removing the herbicide atrazine from solution. The sorption behavior of compost-based char was compared with that of an activated carbon derived from corn stillage. When compost was pyrolyzed, the char yield was greater than 45% when heated under air, and 52% when heated under N(2). In contrast, when the corn stillage was pyrolyzed under N(2), the yield was only 22%. The N(2)-BET surface area of corn stillage activated carbon was 439 m(2)/g, which was much greater than the maximum compost char surface area of 72 m(2)/g. However, the sorption affinity of the compost char for dissolved atrazine was comparable to that of the corn stillage activated carbon. This similarity could have resulted from the initial organic waste being subjected to a relatively long period of thermal processes during composting, and thus, the compost was more thermally stable when compared with the raw materials. In addition, microorganisms transformed the organic wastes into amorphous humic substances, and thus, it was likely that the microporisity was enhanced. Although this micropore structure could not be detected by the N(2)-BET method, it was apparent in the atrazine sorption experiment. Overall, the experimental results suggested that the compost sample in current study was a relatively stable material thermally for producing char, and that it has the potential as a feed stock for making high-quality activated carbon.

Comparative sensitivity of five species of macrophytes and six species of algae to atrazine, metribuzin, alachlor, and metolachlor

Science.gov (United States)

Fairchild, James F.; Ruessler, Shane; Carlson, A. Ron

1998-01-01

This study determined the relative sensitivity of five species of aquatic macrophytes and six species of algae to four commonly used herbicides (atrazine, metribuzin, alachlor, and metolachlor). Toxicity tests consisted of 96-h (duckweed and algae) or 14-d (submerged macrophytes) static exposures. The triazine herbicides (atrazine and metribuzin) were significantly more toxic to aquatic plants than were the acetanilide herbicides (alachlor and metolachlor). Toxicity studies ranked metribuzin > atrazine > alachlor > metolachlor in decreasing order of overall toxicity to aquatic plants. Relative sensitivities of macrophytes to these herbicides decreased in the order of Ceratophyllum > Najas > Elodea > Lemna > Myriophyllum. Relative sensitivities of algae to herbicides decreased in the order of Selenastrum > Chlorella > Chlamydomonas > Microcystis > Scenedesmus > Anabaena. Algae and macrophytes were of similar overall sensitivities to herbicides. Data indicated that Selenastrum, a commonly tested green alga, was generally more sensitive compared to other plant species. Lemna minor, a commonly tested floating vascular plant, was of intermediate sensitivity, and was fivefold less sensitive than Ceratophyllum, which was the most sensitive species tested. The results indicated that no species was consistently most sensitive, and that a suite of aquatic plant test species may be needed to perform accurate risk assessments of herbicides.

Accelerated degradation and durability of concrete in cold climates.

Science.gov (United States)

2011-08-01

Degradation of aggregate in concrete can be caused by erosion or fracture, and both cementitious materials and aggregate age over time. : The specification requirements for the degradation of aggregates have been established for hot mix asphalt and f...

Accelerated Aging in Electrolytic Capacitors for Prognostics

Science.gov (United States)

Celaya, Jose R.; Kulkarni, Chetan; Saha, Sankalita; Biswas, Gautam; Goebel, Kai Frank

2012-01-01

The focus of this work is the analysis of different degradation phenomena based on thermal overstress and electrical overstress accelerated aging systems and the use of accelerated aging techniques for prognostics algorithm development. Results on thermal overstress and electrical overstress experiments are presented. In addition, preliminary results toward the development of physics-based degradation models are presented focusing on the electrolyte evaporation failure mechanism. An empirical degradation model based on percentage capacitance loss under electrical overstress is presented and used in: (i) a Bayesian-based implementation of model-based prognostics using a discrete Kalman filter for health state estimation, and (ii) a dynamic system representation of the degradation model for forecasting and remaining useful life (RUL) estimation. A leave-one-out validation methodology is used to assess the validity of the methodology under the small sample size constrain. The results observed on the RUL estimation are consistent through the validation tests comparing relative accuracy and prediction error. It has been observed that the inaccuracy of the model to represent the change in degradation behavior observed at the end of the test data is consistent throughout the validation tests, indicating the need of a more detailed degradation model or the use of an algorithm that could estimate model parameters on-line. Based on the observed degradation process under different stress intensity with rest periods, the need for more sophisticated degradation models is further supported. The current degradation model does not represent the capacitance recovery over rest periods following an accelerated aging stress period.

Partial degradation of five pesticides and an industrial pollutant by ozonation in a pilot-plant scale reactor

International Nuclear Information System (INIS)

Maldonado, M.I.; Malato, S.; Perez-Estrada, L.A.; Gernjak, W.; Oller, I.; Domenech, Xavier; Peral, Jose

2006-01-01

Aqueous solutions of a mixture of several pesticides (alachlor, atrazine, chlorfenvinphos, diuron and isoproturon), considered PS (priority substances) by the European Commission, and an intermediate product of the pharmaceutical industry (α-methylphenylglycine, MPG) chosen as a model industrial pollutant, have been degraded at pilot-plant scale using ozonation. This study is part of a large research project [CADOX Project, A Coupled Advanced Oxidation-Biological Process for Recycling of Industrial Wastewater Containing Persistent Organic Contaminants, Contract No.: EVK1-CT-2002-00122, European Commission, http://www.psa.es/webeng/projects/cadox/index.html[1

Partial degradation of five pesticides and an industrial pollutant by ozonation in a pilot-plant scale reactor

Energy Technology Data Exchange (ETDEWEB)

Maldonado, M.I. [PSA - Plataforma Solar de Almeria, CIEMAT, Crta Senes km 4, Tabernas, Almeria 04200 (Spain); Malato, S. [PSA - Plataforma Solar de Almeria, CIEMAT, Crta Senes km 4, Tabernas, Almeria 04200 (Spain); Perez-Estrada, L.A. [PSA - Plataforma Solar de Almeria, CIEMAT, Crta Senes km 4, Tabernas, Almeria 04200 (Spain); Gernjak, W. [PSA -Plataforma Solar de Almeria, CIEMAT, Crta Senes km 4, Tabernas, Almeria 04200 (Spain); Oller, I. [PSA - Plataforma Solar de Almeria, CIEMAT, Crta Senes km 4, Tabernas, Almeria 04200 (Spain); Domenech, Xavier [Departament de Quimica, Edifici Cn, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Peral, Jose [Departament de Quimica, Edifici Cn, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Barcelona (Spain)]. E-mail: jose.peral@uab.es

2006-11-16

Aqueous solutions of a mixture of several pesticides (alachlor, atrazine, chlorfenvinphos, diuron and isoproturon), considered PS (priority substances) by the European Commission, and an intermediate product of the pharmaceutical industry ({alpha}-methylphenylglycine, MPG) chosen as a model industrial pollutant, have been degraded at pilot-plant scale using ozonation. This study is part of a large research project [CADOX Project, A Coupled Advanced Oxidation-Biological Process for Recycling of Industrial Wastewater Containing Persistent Organic Contaminants, Contract No.: EVK1-CT-2002-00122, European Commission, http://www.psa.es/webeng/projects/cadox/index.html[1

Gas chromatography/ion trap mass spectrometry applied for the analysis of triazine herbicides in environmental waters by an isotope dilution technique

International Nuclear Information System (INIS)

Cai Zongwei; Wang Dongli; Ma, W.T.

2004-01-01

A gas chromatography/ion trap mass spectrometry method was developed for the analysis of simazine, atrazine, cyanazine, as well as the degradation products of atrazine, such as deethylatrazine and deisopropylatrazine in environmental water samples. Isotope dilution technique was applied for the quantitative analysis of atrazine in water at low ng/l levels. One liter of water sample spiked with stable isotope internal standard atrazine-d 5 was extracted with a C 18 solid-phase extraction cartridge. The analysis was performed on an ion trap mass spectrometer operated in MS/MS method. The extraction recoveries were in the range of 83-94% for the triazine herbicides in water at the concentrations of 24, 200, and 1000 ng/l, while poor recoveries were obtained for the degradation products of atrazine. The relative standard deviation (R.S.D.) were within the range of 3.2-16.1%. The detection limits of the method were between 0.75 and 12 ng/l when 1 l of water was analyzed. The method was successfully applied to analyze environmental water samples collected from a reservoir and a river in Hong Kong for atrazine detected at concentrations between 3.4 and 26 ng/l

Semifield testing of a bioremediation tool for atrazine-contaminated soils: evaluating the efficacy on soil and aquatic compartments.

Science.gov (United States)

Chelinho, Sónia; Moreira-Santos, Matilde; Silva, Cátia; Costa, Catarina; Viana, Paula; Viegas, Cristina A; Fialho, Arsénio M; Ribeiro, Rui; Sousa, José Paulo

2012-07-01

The present study evaluated the bioremediation efficacy of a cleanup tool for atrazine-contaminated soils (Pseudomonas sp. ADP plus citrate [P. ADP + CIT]) at a semifield scale, combining chemical and ecotoxicological information. Three experiments representing worst-case scenarios of atrazine contamination for soil, surface water (due to runoff), and groundwater (due to leaching) were performed in laboratory simulators (100 × 40 × 20 cm). For each experiment, three treatments were set up: bioremediated, nonbioremediated, and a control. In the first, the soil was sprayed with 10 times the recommended dose (RD) for corn of Atrazerba and with P. ADP + CIT at day 0 and a similar amount of P. ADP at day 2. The nonbioremediated treatment consisted of soil spraying with 10 times the RD of Atrazerba (day 0). After 7 d of treatment, samples of soil (and eluates), runoff, and leachate were collected for ecotoxicological tests with plants (Avena sativa and Brassica napus) and microalgae (Pseudokirchneriella subcapitata) species. In the nonbioremediated soils, atrazine was very toxic to both plants, with more pronounced effects on plant growth than on seed emergence. The bioremediation tool annulled atrazine toxicity to A. sativa (86 and 100% efficacy, respectively, for seed emergence and plant growth). For B. napus, results point to incomplete bioremediation. For the microalgae, eluate and runoff samples from the nonbioremediated soils were extremely toxic; a slight toxicity was registered for leachates. After only 7 d, the ecotoxicological risk for the aquatic compartments seemed to be diminished with the application of P. ADP + CIT. In aqueous samples obtained from the bioremediated soils, the microalgal growth was similar to the control for runoff samples and slightly lower than control (by 11%) for eluates. Copyright © 2012 SETAC.

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions.

Science.gov (United States)

Toledo-Jaldin, Helen Paola; Blanco-Flores, Alien; Sánchez-Mendieta, Víctor; Martín-Hernández, Osnieski

2017-08-30

Removal potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMA-Br) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The q max is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process.

The Effect of Different Delivery Conditions on the Accelerated Degradation of Structural Steel in the Coal Mine Environment / Wpływ Różnego Stanu Dostawy Na Przyspieszoną Degradację Stali Konstrukcyjnej W Środowisku Kopalnianym

Science.gov (United States)

Pawłowski, Bogdan; Bała, Piotr

2012-12-01

The main objective of this work was to determine the effect of different delivery conditions on the accelerated degradation of structural steels used for lifting beams (rails) of the monorail transport systems. Some of these rails, made of the same steel grade as others, undergoes accelerated corrosion in the coal mine environment. Corrosion degradation occurs much faster (more than two times faster), comparing to the same steel grade rails operated under the same conditions but with different microstructures. However, all the provided rails meet the requirements of appropriate standards for steel on the lifting beams of the monorail transport systems. The investigations were carried out on rails made of the same steel grade but with different microstructures and showed that the main factor influencing the accelerated corrosion degradation of tested steels is the delivery condition, so-called "as rolled" condition. The greatest resistance to the accelerated corrosion showed rails in the normalized or normalizing rolling condition.

In-situ atrazine biodegradation dynamics in wheat (Triticum) crops under variable hydrologic regime

Science.gov (United States)

la Cecilia, Daniele; Maggi, Federico

2017-08-01

A comprehensive biodegradation reaction network of atrazine (ATZ) and its 18 byproducts was coupled to the nitrogen cycle and integrated in a computational solver to assess the in-situ biodegradation effectiveness and leaching along a 5 m deep soil cultivated with wheat in West Wyalong, New South Wales, Australia. Biodegradation removed 97.7% of 2 kg/ha ATZ yearly applications in the root zone, but removal substantially decreased at increasing depths; dechlorination removed 79% of ATZ in aerobic conditions and 18% in anaerobic conditions, whereas deethylation and oxidation removed only 0.11% and 0.15% of ATZ, respectively. The residual Cl mass fraction in ATZ and 4 byproducts was 2.4% of the applied mass. ATZ half-life ranged from 150 to 247 days in the soil surface. ATZ reached 5 m soil depth within 200 years and its concentration increased from 1 ×10-6 to 4 ×10-6 mg/kgdry-soil over time. The correlation between ATZ specific biomass degradation affinity Φ0 and half-life t1/2, although relatively uncertain for both hydrolyzing and oxidizing bacteria, suggested that microorganisms with high Φ0 led to low ATZ t1/2. Greater ATZ applications were balanced by small nonlinear increments of ATZ biodegraded fraction within the root zone and therefore less ATZ leached into the shallow aquifer.

Analysis of accelerated degradation of a HT-PEM fuel cell caused by cell reversal in fuel starvation condition

DEFF Research Database (Denmark)

Zhou, Fan; Andreasen, Søren Juhl; Kær, Søren Knudsen

2015-01-01

This paper reports an accelerated degradation test of a high temperature PEM fuel cell under repeated H2 starvation condition. The H2 stoichiometry is cycled between 3.0 and 0.8 every 2 min during the test. The experimental results show that the polarity of the fuel cell is reversed under H2......, there is only a slight decrease in open circuit voltage of the fuel cell which implies the membrane is not affected by the test. The electrochemical impedance spectrum measurement shows that the H2 starvation can cause significant increase in the ohmic resistance and charge transfer resistance. By looking...... starvation condition, and the cell performance indicated by cell voltage at H2 stoichiometry of 3.0 declines from 0.59 V to 0.41 V in 19 cycles. Since CO2 is detected in anode exhaust under H2 starvation condition, carbon corrosion is believed to be the reason for the degradation in this test. After the test...

Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME)

NARCIS (Netherlands)

Benhabib, K.; Town, R.M.; Leeuwen, van H.P.

2009-01-01

Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the

Accelerated degradation of polyetheretherketone and its composites in the deep sea

Science.gov (United States)

Liu, Hao; Wang, Jianzhang; Jiang, Pengfei; Yan, Fengyuan

2018-04-01

The performance of polymer composites in seawater, under high hydrostatic pressure (typically few tens of MPa), for simulating exposures at great depths in seas and oceans, has been little studied. In this paper, polyetheretherketone (PEEK) and its composites reinforced by carbon fibres and glass fibres were prepared. The seawater environment with different seawater hydrostatic pressure ranging from normal pressure to 40 MPa was simulated with special equipment, in which the seawater absorption and wear behaviour of PEEK and PEEK-based composites were examined in situ. The effects of seawater hydrostatic pressure on the mechanical properties, wear resistance and microstructure of PEEK and its composites were focused on. The results showed that seawater absorption of PEEK and its composites were greatly accelerated by increased hydrostatic pressure in the deep sea. Affected by seawater absorption, both for neat PEEK and composites, the degradation on mechanical properties, wear resistance and crystallinity were induced, the degree of which was increasingly serious with the increase of hydrostatic pressure of seawater environment. There existed a good correlation in an identical form of exponential function between the wear rate and the seawater hydrostatic pressure. Moreover, the corresponding mechanisms of the effects of deep-sea hydrostatic pressure were also discussed.

VUV/UV light inducing accelerated phenol degradation with a low electric input† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6ra26043h Click here for additional data file.

Science.gov (United States)

Li, Mengkai; Wen, Dong

2017-01-01

This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4–6 min. The HO˙ and HO2˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H2O2 and Fe3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H2O2 or Fe3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants. PMID:28496972

Remoção de atrazina e metabólitos pela filtração lenta com leito de areia e carvão ativado granular Removal of atrazine and metabolites through slow filtration by sand and granular activated carbon

Directory of Open Access Journals (Sweden)

Edumar Ramos Cabral Coelho

2012-09-01

Full Text Available A atrazina (ATZé um herbicida largamente utilizado no mundo, sendo encontrada associada aos seus produtos de degradação em águas superficiais e subterrâneas. Pertence à classe das s-triazinas e, juntamente com os metabólitos clorados deetilatrazina (DEA e deisopropilatrazina (DIA, possui potencial carcinogênico e toxicidade como disruptores endócrinos. A limitação dos processos que empregam a coagulação química na remoção de ATZ, a conhecida capacidade do carvão ativado em remover microcontaminantes em água e o risco que a ATZ e seus metabólitos apresentam à saúde motivaram o estudo da filtração lenta com leito de areia e carvão ativado granular. Os resultados apontaram a eficiência do processo de filtração lenta com camada intermediária de carvão ativado granular na remoção de ATZ e a limitação deste na remoção dos metabólitos DEA, DIA e deetilhidroxiatrazina (DEHA.Atrazine (ATZ is widely used as herbicide, commonly found in association to its degradation products in surface water and groundwater. It belongs to the class of s-triazines and together with the chlorinated metabolites dieethylatrazine (DEA and deisopropilatrazine (DIA have carcinogenic potential and toxicity as endocrine disruptors. The limitation of the processes employing chemical coagulation in the removal of atrazine, the known ability of activated carbon to remove microcontaminants in water and the risk that atrazine and the potential toxicity to human health of its metabolits motivated the study of slow sand filtration bed combined with granular activated carbon. The results showed the high efficiency of the slow filtration process with intermediate layer of granular activated carbon in the removal of atrazine and its limitation on the removal of the metabolites DEA, DIA and diethylhidroxiatrazine (DEHA.

Atrazine triggers developmental abnormality of ovary and oviduct in quails (Coturnix Coturnix coturnix) via disruption of hypothalamo-pituitary-ovarian axis

International Nuclear Information System (INIS)

Qin, Lei; Du, Zheng-Hai; Zhu, Shi-Yong; Li, Xue-Nan; Li, Nan; Guo, Jing-Ao; Li, Jin-Long; Zhang, Ying

2015-01-01

There has been a gradual increase in production and consumption of atrazine (ATR) in agriculture to meet the population rising demands. Female reproduction is necessary for growth and maintenance of population. However, ATR impact on females and particularly ovarian developmental toxicity is less clear. The aim of this study was to define the pathways by which ATR exerted toxic effects on ovarian development of ovary and hypothalamo-pituitary-ovarian (HPO) axis. Female quails were dosed by oral gavage from sexual immaturity to maturity with 0, 50, 250 and 500 mg ATR/kg/d for 45 days. ATR had no effect on mortality but depressed feed intake and growth and influenced the biochemical parameters. Notably, the arrested development of ovaries and oviducts were observed in ATR-exposed quails. The circulating concentrations of E2, P, LH and PRL were unregulated and FSH and T was downregulated in ATR-treated quails. The mRNA expression of GnRH in hypothalamo and LH in pituitary and FSH in ovary was downregulated significantly by ATR exposure and FSH and PRL in pituitary were upregulated. ATR exposure upregulated the level of P450scc, P450arom, 3β-HSD and 17β-HSD in ovary and downregulated ERβ expression in female quails. However, ATR did not change ERα expression in ovary. This study provides new insights regarding female productive toxicology of ATR exposure. Ovary and oviduct in sexually maturing females were target organs of ATR-induced developmental toxicity. We propose that ATR-induced developmental abnormality of ovary and oviduct is associated with disruption of gonadal hormone balance and HPO axis in female quails. - Highlights: • ATR triggers arrested development of ovarian and oviduct. • Ovary and oviduct are target organs of ATR-induced developmental toxicity. • Atrazine causes hormone adjustment disorder in female quails. • Atrazine upregulates steroidogenic factor and downregulates ERβ factor in ovary. • Atrazine disrupted the hypothalamo

Fast algal eco-toxicity assessment: Influence of light intensity and exposure time on Chlorella vulgaris inhibition by atrazine and DCMU.

Science.gov (United States)

Camuel, Alexandre; Guieysse, Benoit; Alcántara, Cynthia; Béchet, Quentin

2017-06-01

In order to develop a rapid assay suitable for algal eco-toxicity assessments under conditions representative of natural ecosystems, this study evaluated the short-term (Chlorella vulgaris was exposed to these herbicides under 'standard' low light intensity (as prescribed by OECD201 guideline), the 20min-EC 50 values recorded via oxygen productivity (atrazine: 1.32±0.07μM; DCMU: 0.31±0.005μM) were similar the 96-h EC 50 recorded via algal growth (atrazine: 0.56μM; DCMU: 0.41μM), and within the range of values reported in the literature. 20min-EC50 values increased by factors of 3.0 and 2.1 for atrazine and DCMU, respectively, when light intensity increased from 60 to 1400μmolm -2 s -1 of photosynthetically active radiation, or PAR. Further investigation showed that exposure time significantly also impacted the sensitivity of C. vulgaris under high light intensity (>840μmolm -2 s -1 as PAR) as the EC 50 for atrazine and DCMU decreased by up to 6.2 and 2.1 folds, respectively, after 50min of exposure at a light irradiance of 1400μmolm -2 s -1 as PAR. This decrease was particularly marked at high light intensities and low algae concentrations and is explained by the herbicide disruption of the electron transfer chain triggering photo-inhibition at high light intensities. Eco-toxicity assessments aiming to understand the potential impact of toxic compounds on natural ecosystems should therefore be performed over sufficient exposure times (>20min for C. vulgaris) and under light intensities relevant to these ecosystems. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of Pseudomonas species on the release of bound 14C residues from soil treated with [14C]atrazine

International Nuclear Information System (INIS)

Khan, S.U.; Behki, R.M.

1990-01-01

The release of bound (nonextractable) 14 C residues from soil previously treated with [ 14 C]atrazine was investigated by incubation of the solvent-extracted soil with two species of Pseudomonas capable of metabolizing atrazine. The two species, 192 and 194, released bound 14 C residues from the soil. Addition of glucose, known to increase microbiological activities, to the incubated soil appeared to enhance the release of soil-bound 14 C residues, in particular in the presence of Pseudomonas species 192. The 14 C bound residues in soil, mainly present as the parent compound and its hydroxy and monodealkylated analogues, were released into the incubation mixture and were subsequently metabolized by the two species involving dechlorination and dealkylation

In vitro Degradation of Butanediamine-Grafted Poly(DL-Lactic acids)

Institute of Scientific and Technical Information of China (English)

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2007-01-01

The degradation of butanediamine-grafted poly(DL-lactic acid) polymers (BDPLAs) in vitro together with PDLLA and maleic anhydride-grafted poly(DL-lactic acid) polymers (MPLAs) was investigated by observation of the changes of the pH value of incubation media, and weight loss ratio during degradation duration of 12 weeks. The results reveal that the acidity of PDLLA degradation products was weakened or neutralized by grafting butanediamine onto PDLLA. A uniform degradation of BDPLAs was observed in comparison with an acidity-induced auto-accelerating degradation featured by PDLLA and MPLAs. The biodegradation behaviors of BDPLAs can be adjusted by controlling the content of BDA. BDPLAs might be a new derivative of PDLLA-based biodegradable materials for medical applications without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as that of PDLLA.

Liquid-liquid extraction assisted by a carbon nanoparticles interface. Electrophoretic determination of atrazine in environmental samples.

Science.gov (United States)

Caballero-Díaz, Encarnación; Simonet, Bartolomé; Valcárcel, Miguel

2013-10-21

A novel method for the determination of atrazine, using liquid-liquid extraction assisted by a nanoparticles film formed in situ and composed of organic solvent stabilized-carbon nanoparticles, is described. The presence of nanoparticles located at the liquid-liquid interface reinforced the extraction of analyte from matrix prior to capillary electrophoresis (CE) analysis. Some influential experimental variables were optimized in order to enhance the extraction efficiency. The developed procedure confirmed that carbon nanoparticles, especially multi-walled carbon nanotubes, are suitable to be used in sample treatment processes introducing new mechanisms of interaction with the analyte. The application of the proposed preconcentration method followed by CE detection enabled the determination of atrazine in spiked river water providing acceptable RSD values (11.6%) and good recoveries (about 87.0-92.0%). Additionally, a similar extraction scheme was tested in soil matrices with a view to further applications in real soil samples.

Effects of atrazine in fish, amphibians, and reptiles: an analysis based on quantitative weight of evidence.

Science.gov (United States)

Van Der Kraak, Glen J; Hosmer, Alan J; Hanson, Mark L; Kloas, Werner; Solomon, Keith R

2014-12-01

A quantitative weight of evidence (WoE) approach was developed to evaluate studies used for regulatory purposes, as well as those in the open literature, that report the effects of the herbicide atrazine on fish, amphibians, and reptiles. The methodology for WoE analysis incorporated a detailed assessment of the relevance of the responses observed to apical endpoints directly related to survival, growth, development, and reproduction, as well as the strength and appropriateness of the experimental methods employed. Numerical scores were assigned for strength and relevance. The means of the scores for relevance and strength were then used to summarize and weigh the evidence for atrazine contributing to ecologically significant responses in the organisms of interest. The summary was presented graphically in a two-dimensional graph which showed the distributions of all the reports for a response. Over 1290 individual responses from studies in 31 species of fish, 32 amphibians, and 8 reptiles were evaluated. Overall, the WoE showed that atrazine might affect biomarker-type responses, such as expression of genes and/or associated proteins, concentrations of hormones, and biochemical processes (e.g. induction of detoxification responses), at concentrations sometimes found in the environment. However, these effects were not translated to adverse outcomes in terms of apical endpoints. The WoE approach provided a quantitative, transparent, reproducible, and robust framework that can be used to assist the decision-making process when assessing environmental chemicals. In addition, the process allowed easy identification of uncertainty and inconsistency in observations, and thus clearly identified areas where future investigations can be best directed.

Sorption of diuron, atrazine, and copper ion on chars with long-term natural oxidation in soils

Science.gov (United States)

Cheng, C.; Lin, T.; Lai, C.

2011-12-01

Biochar has been proposed as a measure to sequestrate carbon (C) and to increase soil fertility in sustainable agriculture. However, its sorption characteristics to herbicides, such as lowing herbicides efficacy, may constrain its agricultural application. This assertion may be arguable because most studies so far were conducted with the newly produced char and barely considered the "ageing effect" of old char since it could be oxidized over long time. In this study, historical char samples were collected and compared with the newly produced char. Batch sorption studies of diuron, atrazine, and copper ion onto chars was performed. Greater sorption of Cu was observed on the historical char samples and reached a saturated sorption at 30 mg g-1 for Cu, much higher adsorption value than newly produced char at 4 mg g-1. In contrast, sorption of diuron and atrazine on newly produced char had the highest sorption capacity than the historical char samples. The historical chars also had much higher negative charge than the newly produced char, but its surface area were lower than the new char. The results indicated that change in surface functional groups through natural oxidation rather than the change of surface area may have more pronounced influences on sorption characteristics, in which the negative charge on the historical chars' surface could hinder the adsorption of diuron and atrazine while enhance the sorption to copper ion. Biological assay to test the toxicity of diuron and copper ion for both historical and new chars on rye seed were conducted and will be presented in our poster.

Results from the RACE [Ring ACceleration Experiment] Compact Torus Acceleration Experiment

International Nuclear Information System (INIS)

Hammer, J.H.; Hartman, C.W.; Eddleman, J.L.; Kusse, B.

1987-06-01

RACE (Ring ACceleration Experiment) is a proof-of-principle experiment aimed at demonstrating acceleration of magnetically confined compact torus plasma rings to directed kinetic energies well in excess of their magnetic and thermal energies. In the course of the first year of operation the following have been observed: successful formation of rings in the RACE geometry; acceleration of rings with large forces, F/sub accelerate/ ∼F/sub equilibrium/ without apparent degradation of the ring structure; peak velocities of ≅2.5 x 10 8 cm/sec; acceleration efficiency of >30% at speeds of 1.5 x 10 8 cm/sec inferred from trajectory and capacitor bank data; kinetic to magnetic energy ratios ∼10 were observed. Experiments in the near future will be aimed at confirmation of the mass/energy measurements by calorimetry and direct density measurements

The inhibition of myometrial contractions by chlorinated herbicides (atrazine and linuron), and their disruptive effect on the secretory functions of uterine and ovarian cells in cow, in vitro.

Science.gov (United States)

Wrobel, Michał H; Mlynarczuk, Jaroslaw

2017-10-01

The effect of atrazine and linuron, the popular and widely used chlorinated herbicides, on both myometrial contractions and secretory functions of bovine uterus and ovaries in vitro, was investigated. The pesticides inhibited (Pherbicides affected PGs secretion from myometrium and PGF2α from endometrium. Only the lowest dose of both tested compounds decreased PGE2 secretion from endometrium. The pesticides increased (P<0.05) the OT secretion from granulosa. However, only linuron stimulated (P<0.05) the OT secretion from the luteal cells, and it increased (P<0.05) the expression of mRNA for the OT precursor. Both compounds stimulated (P<0.05) the secretion of testosterone and atrazine increased (P<0.05) also the secretion of estradiol from the granulosa cells. While atrazine and linuron reduced (P<0.05) the progesterone secretion from the luteal cells. The data show that atrazine and linuron altered the secretory functions of ovarian cells and inhibited the myometrial contractions in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Degradation of fifteen emerging contaminants at microg L(-1) initial concentrations by mild solar photo-Fenton in MWTP effluents.

Science.gov (United States)

Klamerth, N; Rizzo, L; Malato, S; Maldonado, Manuel I; Agüera, A; Fernández-Alba, A R

2010-01-01

The degradation of 15 emerging contaminants (ECs) at low concentrations in simulated and real effluent of municipal wastewater treatment plant with photo-Fenton at unchanged pH and Fe=5 mg L(-1) in a pilot-scale solar CPC reactor was studied. The degradation of those 15 compounds (Acetaminophen, Antipyrine, Atrazine, Caffeine, Carbamazepine, Diclofenac, Flumequine, Hydroxybiphenyl, Ibuprofen, Isoproturon, Ketorolac, Ofloxacin, Progesterone, Sulfamethoxazole and Triclosan), each with an initial concentration of 100 microg L(-1), was found to depend on the presence of CO(3)(2-) and HCO(3)(-) (hydroxyl radicals scavengers) and on the type of water (simulated water, simulated effluent wastewater and real effluent wastewater), but is relatively independent of pH, the type of acid used for release of hydroxyl radicals scavengers and the initial H(2)O(2) concentration used. Toxicity tests with Vibrio fisheri showed that degradation of the compounds in real effluent wastewater led to toxicity increase. (c) 2009 Elsevier Ltd. All rights reserved.

Atrazine and nitrate in drinking water and the risk of preterm delivery and low birth weight in four Midwestern states.

Science.gov (United States)

Stayner, Leslie Thomas; Almberg, Kirsten; Jones, Rachael; Graber, Judith; Pedersen, Marie; Turyk, Mary

2017-01-01

Atrazine and nitrate are common contaminants in water, and there is limited evidence that they are associated with adverse birth outcomes. The objective of this study was to examine whether atrazine and nitrate in water are associated with an increased risk of preterm delivery (PTD) and term low birth weight (LBW). The study included a total of 134,258 singletons births born between January 1, 2004 and December 31, 2008 from 46 counties in four Midwestern states with public water systems that were included in the U.S. Environmental Protection Agency (EPA)'s atrazine monitoring program (AMP). Counties with a population of >300,000 were eliminated from the analyses in order to avoid confounding by urbanicity. Monthly child's sex, race and Hispanic ethnicity specific data were obtained from the states for estimating rates of PTD (nitrate in finished water. Multivariable negative binomial models were fitted to examine the association between the exposures and the adverse birth outcomes. Models were fitted with varying restrictions on the percentage of private well usage in the counties in order to limit the degree of exposure misclassification. Estimated water concentrations of atrazine (mean=0.42 ppb) and nitrate (mean=0.95ppm) were generally low. Neither contaminant was associated with an increased risk of term LBW. Atrazine exposure was associated with a significant increased rate of PTD when well use was restricted to 10% and the exposure was averaged over 4-6 months prior to birth (Rate Ratio for 1ppm increase [RR 1ppm ]=1.08, 95%CI=1.05,1.11) or over 9 months prior to birth (RR 1ppm =1.10, 95%CI=1.01,1.20). Atrazine exposure was also associated with an increased rate of VPTD when when well use was restricted to 10% and the exposure was averaged over 7-9 months prior to birth (RR 1ppm =1.19, 95%CI=1.04,1.36). Exposure to nitrate was significantly associated with an increased rate of VPTD (RR 1ppm =1.08, 95%CI=1.02,1.15) and VLBW (RR 1ppm =1.17, 95%CI=1

A highly sensitive immunoassay for atrazine based on covalently linking the small molecule hapten to a urea-glutaraldehyde network on a polystyrene surface.

Science.gov (United States)

Sai, Na; Sun, Wenjing; Wu, Yuntang; Sun, Zhong; Yu, Guanggui; Huang, Guowei

2016-11-01

A new enzyme-linked immunosorbent assay (ELISA) for atrazine was developed based on covalent bonding of the small molecule hapten, 2-mercaptopropionic acid-4-ethylamino-6-isopropylamino-1,3,5-triazine (MPA-atrazine), to urea-glutaraldehyde (UGA)-treated microtiter plates. In this assay, the microtiter plate surface was treated with the UGA network to both introduce amino groups, which were used to cross-link with the hapten carboxylate groups, and efficiently prevent non-specific adsorption of antibodies, which successfully eliminated the time-consuming routine blocking step. Compared with HNO 3 -H 2 SO 4 -APTES-hapten coated ELISA (modified with a HNO 3 -H 2 SO 4 -APTES mixture and covalent-linked hapten) and conventional ELISA (coated with hapten-carrier protein conjugates), the novel ELISA format increased the sensitivity by approximately 3.5-fold and 7.5-fold, respectively, and saved 2.5h and 34h of coating hapten time, respectively. The method's 50% inhibition concentration for atrazine was 5.54ngmL -1 , and the limit of detection was 0.16ngmL -1 after optimization of reaction conditions. Furthermore, the ELISA was adapted for analysis of atrazine in corn, rice, and water samples, demonstrating recoveries of 90%-108%. Thus, the assay provides a convenient alternative to conventional, laborious immunoassays for routine supervision of residue detection in food and the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma concentrations of estradiol and testosterone, gonadal aromatase activity and ultrastructure of the testis in Xenopus laevis exposed to estradiol or atrazine

International Nuclear Information System (INIS)

Hecker, Markus; Kim, Wan Jong; Park, June-Woo; Murphy, Margaret B.; Villeneuve, Daniel; Coady, Katherine K.; Jones, Paul D.; Solomon, Keith R.; Kraak, Glen van der; Carr, James A.; Smith, Ernest E.; Preez, Louis du; Kendall, Ronald J.; Giesy, John P.

2005-01-01

The ultrastructure of testicular cells of adult male African clawed frogs (Xenopus laevis) exposed to either estradiol (0.1 μg/L) or 2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine (atrazine; 10 or 100 μg/L) was examined by electron microscopy and compared to plasma concentrations of the steroid hormones, testosterone (T) and estradiol (E2), testicular aromatase activity and gonad growth expressed as the gonado-somatic index (GSI). Exposure to E2 caused significant changes both at the sub-cellular and biochemical levels. Exposure to E2 resulted in significantly fewer sperm cells, inhibition of meiotic division of germ cells, more lipid droplets that are storage compartments for the sex steroid hormone precursor cholesterol, and lesser plasma T concentrations. Although not statistically significant, frogs exposed to E2 had slightly smaller GSI values. These results may be indicative of an inhibition of gonad growth and disrupted germ cell development by E2. Concentrations of E2 in plasma were greater in frogs exposed to E2 in water. Exposure to neither concentration of atrazine caused effects on germ cell development, testicular aromatase activity or plasma hormone concentrations. These results suggest that atrazine does not affect testicular function. In contrast, exposure of male X. laevis to E2 led to sub-cellular events that are indicative of disruption of testicular development, and demasculinization processes (decrease of androgen hormone titers). These results indicate that atrazine does not cause responses that are similar to those caused by exposure to E2

Health risks resulting from contaminants transfers in soil-plants systems: case study of Atrazine in Lactuca sativa.

Science.gov (United States)

Mathieu, Camoin

2015-04-01

Food safety is presently at the center of great part of scientific and political debates. This represents a field of study in its own right of health risks, including ingestion by humans of hazardous biological, physical, chemical or radiological substances, from contaminated foods during different stages of production. Plant cultivation step is often one of the main sources of contamination, whether of voluntary (pesticide application) or accidental (nuclear, industrial waste, etc.) origin. As a result, the plants growth in an contaminated environment may increase the risk of transfer within the plant, and finally the exposure of humans. Furthermore, pesticides are among the main contaminants investigated in the frame of human health risks resulting from food intakes. However, most of these scientific works focus mainly on their occurrence and persistence in water bodies, and few of them are interested in soil/plants transfer. In this context, the understanding of the processes governing transfers of pesticides in plants is become a necessity, in particular to prevent human risks linked the ingestion of food produced in contaminated environments. This objective can be reached by studying the pollutants behavior in soils/plants transfers, and using various substances/plants couples. In our study, we selected a salad/pesticide couple as our experimental model. Atrazine was chosen as model contaminant because of its problematic presence in a large amount of environmental compartments, its physico-chemical properties and because of its long-term toxicity. Lactuca sativa has been selected as model plant because of its importance in French agriculture, and specifically in Languedoc-Roussillon. Salad has been cultivated in peats and irrigated with an atrazine spiked water solution (concentrations from 10 to 100 μg/L). Plant growth in such conditions has been compared to a growth in clean condition (irrigation with non spiked water). Measurements of atrazine contents in

Rapid detection of atrazine and metolachlor in farm soils: gas chromatography-mass spectrometry-based analysis using the bubble-in-drop single drop microextraction enrichment method.

Science.gov (United States)

Williams, D Bradley G; George, Mosotho J; Marjanovic, Ljiljana

2014-08-06

Tracking of metolachlor and atrazine herbicides in agricultural soils, from spraying through to harvest, was conducted using our recently reported "bubble-in-drop single-drop microextraction" method. The method showed good linearity (R(2) = 0.999 and 0.999) in the concentration range of 0.01-1.0 ng/mL with LOD values of 0.01 and 0.02 ng/mL for atrazine and metolachlor, respectively. Sonication methods were poor at releasing these herbicides from the soil matrixes, while hot water extraction readily liberated them, providing an efficient accessible alternative to sonication techniques. Good recoveries of 97% and 105% were shown for atrazine and metolachlor, respectively, from the soil. The spiking protocol was also investigated, resulting in a traceless spiking method. We demonstrate a very sensitive technique by which to assess, for example, the length of residence of pesticides in given soils and thus risk of exposure.

New Technologys in Atrazine Removal from Environment with Emphasis on Biodegradation: A Review

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Z Derakhshan

2016-09-01

Full Text Available Introduction:Considering the lack of agricultural lands and the loss of products by pests, utilization of pesticides like atrazine has increased. Due to low vapor pressure, high half-life, and high mobility, this herbicide results in pollution of different ecosystems. In regard with its toxicity, US Environmental Protection Agency has ranked atrazine in III class. Due to its potential capacity in polluting groundwater, it is highly significant. Methods: Many chemical and physical methods have been introduced to remove this herbicide from soil and water environments; however, these methods involve high expenses and cause the creation of other toxic products. Due to development of the science of interaction between man and nature, nowadays biological treatment is uniquely significant. Biological treatment is a process in which microorganisms are utilized to convert and decompose pollutants existing in the environment. Conclusion: Biodegradation is economically and environmentally the best approach to remove long-standing pollutants from the environment. Nowadays, genetic engineering extensively utilizes local or modified microorganisms in treating the environments polluted with pesticides. Finally, in order to further utilize this green technology, it is necessary to specify the soil properties and also conduct ecotoxicological studies in order to identify the capacity of local microorganisms of water and soil.

Degradation of polyethylene microplastics in seawater: Insights into the environmental degradation of polymers.

Science.gov (United States)

Da Costa, João P; Nunes, Ana R; Santos, Patrícia S M; Girão, Ana V; Duarte, Armando C; Rocha-Santos, Teresa

2018-04-06

Microplastic contamination of aquatic environments has become an increasingly alarming problem. These, defined as particles degradation of this material. These results highlight the importance of determining the mechanisms of degradation of microplastics in marine settings and what the implications may be for the environment. Overall, the herein presented results show that a relatively short period of time of accelerated exposure can yield quantifiable chemical and physical impacts on the structural and morphological characteristics of PE pellets.

Evaluated fate and effects of atrazine and lambda-cyhalothrin in vegetated and unvegetated microcosms.

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Bouldin, J L; Farris, J L; Moore, M T; Smith, S; Stephens, W W; Cooper, C M

2005-10-01

Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best-management practices. Our research has shown that the presence of macrophytes and a hydrologic regime aid in the transfer and transformation of pesticides associated with agricultural runoff. This study consisted of application of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms in order to measure the fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through concentrations of atrazine and lambda-cyhalothrin in plant tissue as high as 2461.4 and 86.50 microg/kg, respectively. Toxicity was measured in water from unvegetated microcosms for 28 days and in Chironomus tentans (midge larvae) exposed to sediment collected from 3 h to 56 days in microcosms receiving the pesticide combination. The comparative survival of test organisms in this study suggests that effective mitigation of pesticides from runoff can depend on the macrophyte contact and vegetative attributes associated with ditches. (c) 2005 Wiley Periodicals, Inc.

Calreticulin-mutant proteins induce megakaryocytic signaling to transform hematopoietic cells and undergo accelerated degradation and Golgi-mediated secretion

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Lijuan Han

2016-05-01

Full Text Available Abstract Background Somatic calreticulin (CALR, Janus kinase 2 (JAK2, and thrombopoietin receptor (MPL mutations essentially show mutual exclusion in myeloproliferative neoplasms (MPN, suggesting that they activate common oncogenic pathways. Recent data have shown that MPL function is essential for CALR mutant-driven MPN. However, the exact role and the mechanisms of action of CALR mutants have not been fully elucidated. Methods The murine myeloid cell line 32D and human HL60 cells overexpressing the most frequent CALR type 1 and type 2 frameshift mutants were generated to analyze the first steps of cellular transformation, in the presence and absence of MPL expression. Furthermore, mutant CALR protein stability and secretion were examined using brefeldin A, MG132, spautin-1, and tunicamycin treatment. Results The present study demonstrates that the expression of endogenous Mpl, CD41, and the key megakaryocytic transcription factor NF-E2 is stimulated by type 1 and type 2 CALR mutants, even in the absence of exogenous MPL. Mutant CALR expressing 32D cells spontaneously acquired cytokine independence, and this was associated with increased Mpl mRNA expression, CD41, and NF-E2 protein as well as constitutive activation of downstream signaling and response to JAK inhibitor treatment. Exogenous expression of MPL led to constitutive activation of STAT3 and 5, ERK1/2, and AKT, cytokine-independent growth, and reduction of apoptosis similar to the effects seen in the spontaneously outgrown cells. We observed low CALR-mutant protein amounts in cellular lysates of stably transduced cells, and this was due to accelerated protein degradation that occurred independently from the ubiquitin-proteasome system as well as autophagy. CALR-mutant degradation was attenuated by MPL expression. Interestingly, we found high levels of mutated CALR and loss of downstream signaling after blockage of the secretory pathway and protein glycosylation. Conclusions These

Effects of atrazine, metolachlor, carbaryl and chlorothalonil on benthic microbes and their nutrient dynamics.

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Daniel Elias

Full Text Available Atrazine, metolachlor, carbaryl, and chlorothalonil are detected in streams throughout the U.S. at concentrations that may have adverse effects on benthic microbes. Sediment samples were exposed to these pesticides to quantify responses of ammonium, nitrate, and phosphate uptake by the benthic microbial community. Control uptake rates of sediments had net remineralization of nitrate (-1.58 NO3 µg gdm⁻¹ h⁻¹, and net assimilation of phosphate (1.34 PO4 µg gdm⁻¹ h⁻¹ and ammonium (0.03 NH4 µg gdm⁻¹ h⁻¹. Metolachlor decreased ammonium and phosphate uptake. Chlorothalonil decreased nitrate remineralization and phosphate uptake. Nitrate, ammonium, and phosphate uptake rates are more pronounced in the presence of these pesticides due to microbial adaptations to toxicants. Our interpretation of pesticide availability based on their water/solid affinities supports no effects for atrazine and carbaryl, decreasing nitrate remineralization, and phosphate assimilation in response to chlorothalonil. Further, decreased ammonium and phosphate uptake in response to metolachlor is likely due to affinity. Because atrazine target autotrophs, and carbaryl synaptic activity, effects on benthic microbes were not hypothesized, consistent with results. Metolachlor and chlorothalonil (non-specific modes of action had significant effects on sediment microbial nutrient dynamics. Thus, pesticides with a higher affinity to sediments and/or broad modes of action are likely to affect sediment microbes' nutrient dynamics than pesticides dissolved in water or specific modes of action. Predicted nutrient uptake rates were calculated at mean and peak concentrations of metolachlor and chlorothalonil in freshwaters using polynomial equations generated in this experiment. We concluded that in natural ecosystems, peak chlorothalonil and metolachlor concentrations could affect phosphate and ammonium by decreasing net assimilation, and nitrate uptake rates by

Analytical method for the determination of atrazine and its dealkylated chlorotriazine metabolites in water using SPE sample preparation and GC-MSD analysis.

Science.gov (United States)

Huang, Sung-Ben; Stanton, Jeffrey S; Lin, Yi; Yokley, Robert A

2003-12-03

A method is reported for the determination of atrazine and its dealkylated chlorotriazine metabolites in ground, surface, and deionized water. Water samples are adjusted to pH 3-4 prior to loading onto two SPE cartridges in series: C-18 and C-18/cation exchange mixed-mode polymeric phases. The analytes are eluted from each of the two cartridges separately, and the pooled and concentrated fraction is analyzed using gas chromatography-mass selective detection in the selected ion monitoring mode. The lower limit of method validation is 0.10 micrograms/L (ppb) for 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine), 2-amino-4-chloro-6-(isopropylamino)-s-triazine (G-30033, deethylatrazine), 2-amino-4-chloro-6-(ethylamino)-s-triazine (G-28279, deisopropylatrazine), and 2,4-diamino-6-chloro-s-triazine (G-28273, didealkyatrazine). The overall mean procedural recoveries (and standard deviations) are 96 (6.9), 96 (5.5), 95 (6.8), and 100% (10%) for atrazine, G-30033, G-28279, and G-28273, respectively (n = 49). The method validation study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160. The reported procedure accounts for residues of G-28273 in water.

A NEW APPROACH FOR CULTURING LEMNA MINOR (DUCKWEED) AND STANDARDIZED METHOD FOR USING ATRAZINE AS A REFERENCE TOXICANT

Science.gov (United States)

Lemna minor (Duckweed) is commonly used in aquatic toxicity investigations. Methods for culturing and testing with reference toxicants, such as atrazine, are somewhat variable among researchers. Our goal was to develop standardized methods of culturing and testing for use with L....

Solar photocatalytic degradation and detoxification of EU priority substances

Energy Technology Data Exchange (ETDEWEB)

Hincapie, M. [Facultad de Ingeniera Ambiental, Universidad de Medellin, Carrera 87 No. 30-65, P.O. Box 1983, Medellin (Colombia); Maldonado, M.I.; Oller, I.; Gernjak, W.; Malato, S. [Plataforma Solar de Almeria-CIEMAT, Carretera Senes km4, 04200 Tabernas (Almeria) (Spain); Sanchez-Perez, J.A.; Ballesteros, M.M. [Departamento de Ingenieria Quimica, Universidad de Almeria Crta de Sacramento s/n, 04120 Almeria (Spain)

2005-04-15

Several different pesticides (alachlor, atrazine, chlorfenvinphos, diuron, isoproturon and pentachlorophenol) considered PS (priority substances) by the European Commission and dissolved in water at 50mg/L (or at maximum water solubility) have been degraded at pilot-plant scale using photo-Fenton and TiO{sub 2} photocatalysis driven by solar energy. Two different iron concentrations (2 and 55mg/L) and TiO{sub 2} at 200mg/L have been tested and discussed, using mainly TOC mineralisation for comparison of treatment effectiveness. Vibrio fischeri (Microtox{sup (}R)) toxicity assays were also employed for evaluating the photocatalytic treatments, and comparison between these results and parent compound disappearance, TOC evolution and anion (or ammonia) release were discussed. Almost complete mineralisation and total detoxification were always attained. It has been demonstrated that evolution of chloride could be a key-parameter for predicting toxicity of chlorinated compounds.

Degradation model and application in life prediction of rotating-mechanism

International Nuclear Information System (INIS)

Zhou Yuhui

2009-01-01

The degradation data can provide additional information beyond that provided by the failure observations, both sets of observations need to be considered when doing inference on the statistical parameters of the product and system lifetime distributions. By the degradation model showing the wear out failure, the predicted results of mechanism life is more accurate. Strength is one of the important capabilities of the rotating mechanism. In this paper, the degradation data of strength are described as a stochastic process model. Accelerated tests expose the products to greater environmental stress levels so that we can obtain lifetime and degradation measurements in a more timely fashion. Using the Best Linear Unbiased Estimation (BLUE) Method, the parameters under the degradation path were estimated from the accelerated life test (ALT) data of the rotating mechanism. Based on solving the singularity of degradation equation, at any time the reliability is estimated by the using the strength-stress interference theory. So we can predict the life of the rotating mechanism. (authors)

Comparison of efficiency degradation in polycrystalline-Si and CdTe thin-film PV modules via accelerated lifecycle testing

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Lai, T.; Potter, B. G.; Simmons-Potter, K.

2017-08-01

Thin-film solar cells normally have the shortest energy payback time due to their simpler mass-production process compared to polycrystalline-Si photovoltaic (PV) modules, despite the fact that crystalline-Si-based technology typically has a longer total lifetime and a higher initial power conversion efficiency. For both types of modules, significant aging occurs during the first two years of usage with slower long-term aging over the module lifetime. The PV lifetime and the return-on-investment for local PV system installations rely on long-term device performance. Understanding the efficiency degradation behavior under a given set of environmental conditions is, therefore, a primary goal for experimental research and economic analysis. In the present work, in-situ measurements of key electrical characteristics (J, V, Pmax, etc.) in polycrystalline-Si and CdTe thin-film PV modules have been analyzed. The modules were subjected to identical environmental conditions, representative of southern Arizona, in a full-scale, industrial-standard, environmental degradation chamber, equipped with a single-sun irradiance source, temperature, and humidity controls, and operating an accelerated lifecycle test (ALT) sequence. Initial results highlight differences in module performance with environmental conditions, including temperature de-rating effects, for the two technologies. Notably, the thin-film CdTe PV module was shown to be approximately 15% less sensitive to ambient temperature variation. After exposure to a seven-month equivalent compressed night-day weather cycling regimen the efficiency degradation rates of both PV technology types were obtained and will be discussed.

Sorption Energies for Atrazine onto Devolatalized Vitellaria paradoxa

International Nuclear Information System (INIS)

Itodo, A. U.; Abdulrahman, F. W.; Hassan, L. G.; Happiness, U. I.

2012-01-01

We utilize isotherm models in contributing to scholarly knowledge in simple terms, to measure the forces or energy defining certain adsorption phenomenon. Gas Chromatography coupled with Mass Spectrophotometer detector was utilized to measure equilibrium phase atrazine after adsorption onto Shea nut Shells acid derived activated carbon. Data were fitted into the D-R and Temkin isotherm relationships for energy data estimation of Sorption energy value (B D ), mean free energy (E D ) and heat of sorption (B). They were estimated as 0.7600mol 2 KJ -2 , 0.8111 kjmor -1 and 0.790Jmol -1 respectively. The parameter predicting the type of adsorption was evaluated B D , B D 2 = 0.979 proves a better choice in explaining sorption energies. Generally, shea nut shells can be used as alternative precursors for activated carbon production via the two steps and acid treatment method.

Novel molecular events associated with altered steroidogenesis induced by exposure to atrazine in the intact and castrate male rat

Science.gov (United States)

Toxicology is increasingly focused on molecular events comprising adverse outcome pathways. Atrazine activates the hypothalamic-pituitary adrenal axis, but relationships to gonadal alterations are unknown. We characterized hormone profiles and adrenal (intact and castrate) and te...

Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes

Directory of Open Access Journals (Sweden)

Anastasia E. M. Chirnside

2011-01-01

Full Text Available Soils from bulk pesticide mixing and loading (mix-load sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT and alachlor (2-chloro-2, 6-diethyl-N-[methoxymethyl]-acetanilide in contaminated mix-load site soil utilizing an extracellular fungal enzyme solution derived from the white rot fungus, Phanerochaete chrysosporium, grown in a packed bed bioreactor. Thirty-two percent of AT and 54% of AL were transformed in the biometers. The pseudo first-order rate constant for AT and AL biodegradation was 0.0882 d−1 and 0.2504 d−1, respectively. The half-life (1/2 for AT and AL was 8.0 and 3.0 days, respectively. Compared to AT, the initial disappearance of AL proceeded at a faster rate and resulted in a greater amount of AL transformed. Based on the net Co2 evolved from the biometers, about 4% of the AT and AL initially present in the soil was completely mineralized.

Agronomic and environmental implications of enhanced s-triazine degradation

Science.gov (United States)

Krutz, L. J.; Dale L. Shaner,; Mark A. Weaver,; Webb, Richard M.; Zablotowicz, Robert M.; Reddy, Krishna N.; Huang, Y.; Thompson, S. J.

2010-01-01

Novel catabolic pathways enabling rapid detoxification of s-triazine herbicides have been elucidated and detected at a growing number of locations. The genes responsible for s-triazine mineralization, i.e. atzABCDEF and trzNDF, occur in at least four bacterial phyla and are implicated in the development of enhanced degradation in agricultural soils from all continents except Antarctica. Enhanced degradation occurs in at least nine crops and six crop rotation systems that rely on s-triazine herbicides for weed control, and, with the exception of acidic soil conditions and s-triazine application frequency, adaptation of the microbial population is independent of soil physiochemical properties and cultural management practices. From an agronomic perspective, residual weed control could be reduced tenfold in s-triazine-adapted relative to non-adapted soils. From an environmental standpoint, the off-site loss of total s-triazine residues could be overestimated 13-fold in adapted soils if altered persistence estimates and metabolic pathways are not reflected in fate and transport models. Empirical models requiring soil pH and s-triazine use history as input parameters predict atrazine persistence more accurately than historical estimates, thereby allowing practitioners to adjust weed control strategies and model input values when warranted. 

Stability of CIGS Solar Cells and Component Materials Evaluated by a Step-Stress Accelerated Degradation Test Method: Preprint

Energy Technology Data Exchange (ETDEWEB)

Pern, F. J.; Noufi, R.

2012-10-01

A step-stress accelerated degradation testing (SSADT) method was employed for the first time to evaluate the stability of CuInGaSe2 (CIGS) solar cells and device component materials in four Al-framed test structures encapsulated with an edge sealant and three kinds of backsheet or moisture barrier film for moisture ingress control. The SSADT exposure used a 15oC and then a 15% relative humidity (RH) increment step, beginning from 40oC/40%RH (T/RH = 40/40) to 85oC/70%RH (85/70) as of the moment. The voluminous data acquired and processed as of total DH = 3956 h with 85/70 = 704 h produced the following results. The best CIGS solar cells in sample Set-1 with a moisture-permeable TPT backsheet showed essentially identical I-V degradation trend regardless of the Al-doped ZnO (AZO) layer thickness ranging from standard 0.12 μm to 0.50 μm on the cells. No clear 'stepwise' feature in the I-V parameter degradation curves corresponding to the SSADT T/RH/time profile was observed. Irregularity in I-V performance degradation pattern was observed with some cells showing early degradation at low T/RH < 55/55 and some showing large Voc, FF, and efficiency degradation due to increased series Rs (ohm-cm2) at T/RH ≥ 70/70. Results of (electrochemical) impedance spectroscopy (ECIS) analysis indicate degradation of the CIGS solar cells corresponded to increased series resistance Rs (ohm) and degraded parallel (minority carrier diffusion/recombination) resistance Rp, capacitance C, overall time constant Rp*C, and 'capacitor quality' factor (CPE-P), which were related to the cells? p-n junction properties. Heating at 85/70 appeared to benefit the CIGS solar cells as indicated by the largely recovered CPE-P factor. Device component materials, Mo on soda lime glass (Mo/SLG), bilayer ZnO (BZO), AlNi grid contact, and CdS/CIGS/Mo/SLG in test structures with TPT showed notable to significant degradation at T/RH ≥ 70/70. At T/RH = 85/70, substantial blistering of

Biodegradation of {sup 14} C-atrazine under outdoor conditions; Biodegradacao de {sup 14} C-atrazina em condicoes semi controladas

Energy Technology Data Exchange (ETDEWEB)

Queiroz, Brigida Pimentel Villar de

1997-10-01

Uniformly {sup 14} C-ring labeled atrazine (5 L/ha) was applied to a Typical Hapludox Brazilian Soil sample which was incubated under outdoor conditions. Sample of 200 g (dry weight base) of fresh soil were distributed in Erlenmeyer flasks and the moisture was adjusted for 2/3 rds of the soil field capacity. The flasks were then buried in the Lysimeter Station when they were incubated. The experiment started jointly with a corn planting. The {sup 14} C O{sub 2} was analyzed every 15 day, during a period of 150 days. The desorbed, extracted and bound residues were analyzed. The extracted soil was fractionated and the residues in the humin, fulvic and humic acids were determined. At the end of the incubation period (150 days), the {sup 14} CO{sub 2} evolved reached up to 36% of the total applied activity, the bound residues were detected in about the same (34%) during the inoculation period, and were distributed in the fractions of fulvic acids (29,91%), humic acids (6,83%) and humin (63,26%). The metabolites formed in the desorbed residues and in the extracted residues were determined using thin layer chromatography with {sup 14} C-detector. After 150 days incubation, desorbed soil residues were identified as atrazine (52,72%), hydroxiatrazine (44%) and desisopropilatrazine (3,28%). The extractable residues contained atrazine (79,29%), hydroxiatrazine (16,22%), desisopropilatrazine (2,25%) and desetylatrazine (2,24%). (author)

Impacts of Extraction Methods in the Rapid Determination of Atrazine Residues in Foods using Supercritical Fluid Chromatography and Enzyme-Linked Immunosorbent Assay: Microwave Solvent vs. Supercritical Fluid Extractions

Directory of Open Access Journals (Sweden)

Mohamed H. El-Saeid

2005-01-01

Full Text Available It is an accepted fact that many food products that we eat today have the possibility of being contaminated by various chemicals used from planting to processing. These chemicals have been shown to cause illnesses for which some concerned government agencies have instituted regulatory mechanisms to minimize the risks and the effects on humans. It is for these concerns that reliable and accurate rapid determination techniques are needed to effect proper regulatory standards for the protection of people's nutritional health. This paper, therefore, reports the comparative evaluation of the extraction methods in the determination of atrazine (commonly used in agricultural as a herbicide residues in foods using supercritical fluid chromatography (SFC and enzyme-linked immunosorbent assay (ELISA techniques. Supercritical fluid extraction (SFE and microwave solvent extraction (MSE methods were used to test samples of frozen vegetables, fruit juice, and jam from local food markets in Houston. Results showed a high recovery percentage of atrazine residues using supercritical fluid coupled with ELISA and SFC than with MSE. Comparatively, however, atrazine was detected 90.9 and 54.5% using SFC and ELISA techniques, respectively. ELISA technique was, however, less time consuming, lower in cost, and more sensitive with low detection limit of atrazine residues than SFC technique.

Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator

Science.gov (United States)

Shen, Yi; Liu, Yi; Ye, Mao; Zhang, Huang; Wang, Wei; Xia, Liansheng; Wang, Zhiwen; Yang, Chao; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

2017-12-01

A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.

Short-term effects of benzalkonium chloride and atrazine on Elodea canadensis using a miniaturised microbioreactor system for an online monitoring of physiologic parameters.

Science.gov (United States)

Vervliet-Scheebaum, Marco; Ritzenthaler, Raphael; Normann, Johannes; Wagner, Edgar

2008-02-01

The study evaluated the effects of benzalkonium chloride (BAC) and atrazine on the macrophyte Elodea canadensis (Michaux) using a miniaturised monitoring test system consisting of a microbioreactor of reduced volume and integrated sensors for the online measurement of physiologic parameters, like oxygen production and different parameters of fluorescence. Different concentrations of both chemicals were applied to leaves of E. canadensis and the physiologic endpoints evaluated after 1h. A concentration-dependent reduction of the oxygen production and of the effective quantum yield of energy conversion was recorded. The mini-PAM technique implemented in the presented system allowed for a clear monitoring of the kinetic of BAC and atrazine, showing their distinct mode of action. No observable adverse effects were recorded up to concentrations of 2.5 mg/L and 10 microg/L, for BAC and atrazine, respectively. These values are in accordance with available results in the literature, hence indicating that the microbioreactor test system might be suitable, on the one hand, for the laboratory screening of potential short-term toxicity of contaminants on aquatic plants, and on the other hand, serve as an in situ field biomonitoring system for the rapid detection of pollutants in water.

Catalytic Study on TiO2 Photo catalyst Synthesised Via Microemulsion Method on Atrazine

International Nuclear Information System (INIS)

Ruslimie, C.A.; Hasmizam Razali; Khairul, W.M.

2011-01-01

Titanium dioxide photo catalyst was synthesised by microemulsions method under controlled hydrolysis of titanium butoxide, Ti(O(CH 2 ) 3 )CH 3 . The synthesised TiO 2 photo catalyst was compared with Sigma-commercial TiO 2 by carrying out the investigation on its properties using scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis and thermal gravimetric analysis (TGA). The photo catalytic activities for both photo catalysts were studied for atrazine photodegradation. (author)

RESPONSES OF MOLECULAR INDICATORS OF EXPOSURE IN MESOCOSMS: COMMON CARP (CYPRINUS CARPIO) EXPOSED TO THE HERBICIDES ALACHLOR AND ATRAZINE

Science.gov (United States)

Common carp (Cyprinus carpio) were treated in aquatic mesocosms with a single pulse of the herbicides atrazine or alachlor to study the bioavailability and biological activity of these herbicides using molecular indicators: Liver vitellogenin gene expression in male fish for estr...

Degradation of Herbicides in the Tropical Marine Environment: Influence of Light and Sediment.

Science.gov (United States)

Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; O'Brien, Jake; Flores, Florita; Negri, Andrew P

2016-01-01

Widespread contamination of nearshore marine systems, including the Great Barrier Reef (GBR) lagoon, with agricultural herbicides has long been recognised. The fate of these contaminants in the marine environment is poorly understood but the detection of photosystem II (PSII) herbicides in the GBR year-round suggests very slow degradation rates. Here, we evaluated the persistence of a range of commonly detected herbicides in marine water under field-relevant concentrations and conditions. Twelve-month degradation experiments were conducted in large open tanks, under different light scenarios and in the presence and absence of natural sediments. All PSII herbicides were persistent under control conditions (dark, no sediments) with half-lives of 300 d for atrazine, 499 d diuron, 1994 d hexazinone, 1766 d tebuthiuron, while the non-PSII herbicides were less persistent at 147 d for metolachlor and 59 d for 2,4-D. The degradation of herbicides was 2-10 fold more rapid in the presence of a diurnal light cycle and coastal sediments; apart from 2,4-D which degraded more slowly in the presence of light. Despite the more rapid degradation observed for most herbicides in the presence of light and sediments, the half-lives remained > 100 d for the PS II herbicides. The effects of light and sediments on herbicide persistence were likely due to their influence on microbial community composition and its ability to utilise the herbicides as a carbon source. These results help explain the year-round presence of PSII herbicides in marine systems, including the GBR, but more research on the transport, degradation and toxicity on a wider range of pesticides and their transformation products is needed to improve their regulation in sensitive environments.

Degradation of photovoltaic backsheet materials under multi-factor accelerated UV light exposures

Science.gov (United States)

Klinke, Addison G.; Gok, Abdulkerim; Ifeanyi, Silas I.; French, Roger H.; Bruckman, Laura S.

2017-08-01

Long term outdoor durability of photovoltaic (PV) module backsheets is critical to a module's power output over its lifetime. The use of uoropolymer-based backsheets or the addition of stabilizers to polyethylene-terephthalate (PET) and polyamide (PA) type backsheets can help extend their lifetime. This study presents the performance of 21 backsheets made of 8 different material combinations under ASTM G154 Cycle 4 accelerated light exposures. The backsheets were subjected to 4000 hours of high irradiance UVA light at a peak intensity of 1.55 W=m2 at 340 nm at 70°C with and without a condensing humidity cycle at 50°C. Backsheets were evaluated, with repeated measurements, using various evaluation techniques to identify and assess potential signs of degradation. These evaluations included the yellowness index (YI), CIE color space coordinates, and gloss at 20, 60, and 85°. The temporal evolution of the relative color change ΔE was statistically analyzed to develop a stress-response model which used the UVA light dose to predict color change. It was found that the PVF/PET/E backsheet performed the best while PET/PET/E and THV/PET/EVA backsheets performed the worst. Additionally, substantial variation in color change response, attributable to key manufacturing differences, was observed within a given material type.

Compact multi-energy electron linear accelerators

International Nuclear Information System (INIS)

Tanabe, E.; Hamm, R.W.

1985-01-01

Two distinctly different concepts that have been developed for compact multi-energy, single-section, standing-wave electron linear accelerator structures are presented. These new concepts, which utilize (a) variable nearest neighbor couplings and (b) accelerating field phase switching, provide the capability of continuously varying the electron output energy from the accelerator without degrading the energy spectrum. These techniques also provide the means for continuously varying the energy spectrum while maintaining a given average electron energy, and have been tested successfully with several accelerators of length from 0.1 m to 1.9 m. Theoretical amd experimental results from these accelerators, and demonstrated applications of these techniques to medical and industrial linear accelerator technology will be described. In addition, possible new applications available to research and industry from these techniques are presented. (orig.)

Método alternativo de avaliação da absorção de atrazine por plantas de Brachiaria plantaginea Alternative method for evaluation of atrazine asorption by Brachiaria plantaginea plants

Directory of Open Access Journals (Sweden)

C.D.G. Maciel

2002-12-01

Full Text Available Dois experimentos foram conduzidos em casa de vegetação da Universidade Estadual de Maringá-PR, objetivando desenvolver metodologia alternativa para avaliar a absorção foliar e radicular de herbicidas. O delineamento experimental utilizado foi o inteiramente casualizado com 11 e 5 tratamentos para os solos arenoso e argiloso, respectivamente, ambos os experimentos com quatro repetições, constituídos por plantas de B. plantaginea em dois estádios. O herbicida atrazine foi aplicado nas doses de 2,5 e 3,0 kg ha¹ em solos arenoso e argiloso, utilizando um pulverizador costal pressurizado por CO2. Os tratamentos foram constituídos por plantas protegidas com canudos plásticos em solo descoberto e plantas desprotegidas em solo coberto com papel-alumínio, associadas a condições de solo seco e úmido, ou em ambas as condições, acrescidas de irrigação de 20 mm apenas ao solo após aplicação. A absorção foliar da atrazine foi eficiente no controle de B. plantaginea com duas a três folhas em solo arenoso e argiloso, ao contrário do estádio de quatro a cinco folhas, onde houve necessidade de associar os efeitos da absorção foliar e radicular para se obter controle satisfatório. A irrigação de 20 mm ampliou o controle da absorção radicular de B. plantaginea em diferentes estádios de plantas, solo e umidade do solo. A metodologia apresentou-se viável como ferramenta alternativa para avaliação da absorção foliar e radicular de herbicidas, no controle de gramíneas em estádio inicial de desenvolvimento.Two trials were carried out at the Universidade Estadual de Maringá, PR-Brazil, to develop an alternative method to evaluate foliar and root absorption of herbicides. A random experimental design was arranged, with eleven or five treatments, for sandy or clay soils, respectively,both with four replicates. Atrazine was applied at rates of 2.5 or 3.0 kg ha-1 in sandy or clay soil samples, respectively, with a CO2-pressured

Accelerated stress testing of terrestrial solar cells

Science.gov (United States)

Lathrop, J. W.; Hawkins, D. C.; Prince, J. L.; Walker, H. A.

1982-01-01

The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.

Activation of chromatin degradation by a protein factor of thymocyte cytoplasm of irradiated mice

International Nuclear Information System (INIS)

Soldatenkov, V.A.; Filippovich, I.V.

1986-01-01

A cytoplasmic thymocyte fraction isolated 1 h after irradiation of mice accelerates chromatin degradation in isolated nuclei. Treatment of the cytoplasmic fraction by heat and injection of cycloheximide to mice prevent the acceleration of DNA degradation. The analysis of the chromatin degradation products and the kinetics of this process at acid and alkaline pH shows that activation of DNA degradation in thymocytes by a factor obtained from the irradiated cell cytoplasm is specific for a Ca 2+ , Mg 2+ -dependent enzyme. The time- and dose-dependent parameters of the appearance in the thymocyte cytoplasm of the factor influencing degradation of chromatin are in a good agreement with both the time of the onset of its postirradiation degradation and the dose dependence of this process

Degradation Behavior and Accelerated Weathering of Composite Boards Produced from Waste Tetra Pak® Packaging Materials

Directory of Open Access Journals (Sweden)

Nural Yilgo

2014-06-01

Full Text Available Manufacturing panels from Tetra Pak® (TP packaging material might be an alternative to conventional wood-based panels. This study evaluated some chemical and physical properties as well as biological, weathering, and fire performance of panels with and without zinc borate (ZnB by using shredded TP packaging cartons. Such packaging material, a worldwide well-known multilayer beverage packaging system, is composed of cellulose, low-density polyethylene (LDPE, and aluminum (Al. Panels produced from waste TP packaging material were also examined by FT-IR to understand the fungal deterioration and extent of degradation after accelerated weathering. Before FT-IR investigations, panel specimens were ground under nitrogen atmosphere due to non-uniformity of the composite material. The FT-IR results showed that fungal degradation occurred in the natural polymer of the panel matrix. Although the natural polymer is mostly composed of cellulose, there were also small amounts of polyoses and lignin. It was seen that especially polyose and lignin bands in FT-IR spectra were affected more than cellulose bands by fungal attack. No changes were observed by the fungi in the plastic component (LDPE of the matrix; however, LDPE seemed more sensitive to weathering than cellulose. Incorporation of ZnB at loading level of 1% (w/w did not contribute fire performance of the panels when compared to control panel specimens, while a loading level of 10% improved fire performance considering test parameters such as mass loss, ignition time and peak heat release rate.

Estimation of placental and lactational transfer and tissue distribution of atrazine and its main metabolites in rodent dams, fetuses, and neonates with physiologically based pharmacokinetic modeling

International Nuclear Information System (INIS)

Lin, Zhoumeng; Fisher, Jeffrey W.; Wang, Ran; Ross, Matthew K.; Filipov, Nikolay M.

2013-01-01

Atrazine (ATR) is a widely used chlorotriazine herbicide, a ubiquitous environmental contaminant, and a potential developmental toxicant. To quantitatively evaluate placental/lactational transfer and fetal/neonatal tissue dosimetry of ATR and its major metabolites, physiologically based pharmacokinetic models were developed for rat dams, fetuses and neonates. These models were calibrated using pharmacokinetic data from rat dams repeatedly exposed (oral gavage; 5 mg/kg) to ATR followed by model evaluation against other available rat data. Model simulations corresponded well to the majority of available experimental data and suggest that: (1) the fetus is exposed to both ATR and its major metabolite didealkylatrazine (DACT) at levels similar to maternal plasma levels, (2) the neonate is exposed mostly to DACT at levels two-thirds lower than maternal plasma or fetal levels, while lactational exposure to ATR is minimal, and (3) gestational carryover of DACT greatly affects its neonatal dosimetry up until mid-lactation. To test the model's cross-species extrapolation capability, a pharmacokinetic study was conducted with pregnant C57BL/6 mice exposed (oral gavage; 5 mg/kg) to ATR from gestational day 12 to 18. By using mouse-specific parameters, the model predictions fitted well with the measured data, including placental ATR/DACT levels. However, fetal concentrations of DACT were overestimated by the model (10-fold). This overestimation suggests that only around 10% of the DACT that reaches the fetus is tissue-bound. These rodent models could be used in fetal/neonatal tissue dosimetry predictions to help design/interpret early life toxicity/pharmacokinetic studies with ATR and as a foundation for scaling to humans. - Highlights: • We developed PBPK models for atrazine in rat dams, fetuses, and neonates. • We conducted pharmacokinetic (PK) study with atrazine in pregnant mice. • Model predictions were in good agreement with experimental rat and mouse PK data. �

Estimation of placental and lactational transfer and tissue distribution of atrazine and its main metabolites in rodent dams, fetuses, and neonates with physiologically based pharmacokinetic modeling

Energy Technology Data Exchange (ETDEWEB)

Lin, Zhoumeng [Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States); Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602 (United States); Fisher, Jeffrey W. [Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079 (United States); Wang, Ran [Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762 (United States); Institute of Food Safety, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Ross, Matthew K. [Center for Environmental Health Sciences, Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762 (United States); Filipov, Nikolay M., E-mail: filipov@uga.edu [Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States); Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602 (United States)

2013-11-15

Atrazine (ATR) is a widely used chlorotriazine herbicide, a ubiquitous environmental contaminant, and a potential developmental toxicant. To quantitatively evaluate placental/lactational transfer and fetal/neonatal tissue dosimetry of ATR and its major metabolites, physiologically based pharmacokinetic models were developed for rat dams, fetuses and neonates. These models were calibrated using pharmacokinetic data from rat dams repeatedly exposed (oral gavage; 5 mg/kg) to ATR followed by model evaluation against other available rat data. Model simulations corresponded well to the majority of available experimental data and suggest that: (1) the fetus is exposed to both ATR and its major metabolite didealkylatrazine (DACT) at levels similar to maternal plasma levels, (2) the neonate is exposed mostly to DACT at levels two-thirds lower than maternal plasma or fetal levels, while lactational exposure to ATR is minimal, and (3) gestational carryover of DACT greatly affects its neonatal dosimetry up until mid-lactation. To test the model's cross-species extrapolation capability, a pharmacokinetic study was conducted with pregnant C57BL/6 mice exposed (oral gavage; 5 mg/kg) to ATR from gestational day 12 to 18. By using mouse-specific parameters, the model predictions fitted well with the measured data, including placental ATR/DACT levels. However, fetal concentrations of DACT were overestimated by the model (10-fold). This overestimation suggests that only around 10% of the DACT that reaches the fetus is tissue-bound. These rodent models could be used in fetal/neonatal tissue dosimetry predictions to help design/interpret early life toxicity/pharmacokinetic studies with ATR and as a foundation for scaling to humans. - Highlights: • We developed PBPK models for atrazine in rat dams, fetuses, and neonates. • We conducted pharmacokinetic (PK) study with atrazine in pregnant mice. • Model predictions were in good agreement with experimental rat and mouse PK data

Atrazine Does Not Induce Pica Behavior at Doses that Increase Hypothalamic-Pituitary-Adrenal Axis Activation and Cause Conditioned Taste Avoidance.

Science.gov (United States)

Previous work has shown that a single oral administration of atrazine (ATR), a chlorotriazine herbicide, induces dose-dependent increases in plasma adrenocorticotropic hormone (ACTH), serum corticosterone (CORT) and progesterone. The mechanism for these effects is unknown. To tes...

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons; Degradacion de naftaleno y fluoreno por radiolisis empleando electrones acelerados

Energy Technology Data Exchange (ETDEWEB)

Flores de Jesus, I

2003-07-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Degradation of naphthalene and fluorene by radiolysis using accelerated electrons; Degradacion de naftaleno y fluoreno por radiolisis empleando electrones acelerados

Energy Technology Data Exchange (ETDEWEB)

Flores de Jesus, I

2003-07-01

The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

Adsorption and catalytic hydrolysis of carbaryl and atrazine on pig manure-derived biochars: Impact of structural properties of biochars

International Nuclear Information System (INIS)

Zhang, Peng; Sun, Hongwen; Yu, Li; Sun, Tieheng

2013-01-01

Highlights: ► High ash content biochar can increase solution pH and released metal ions. ► Ash in biochar can combine pesticide through specific interactions. ► Composition and structure of biochar is favor for the hydrolysis of pesticides. -- Abstract: Biochars were produced from pig manure to elucidate the influence of biochars with high ash contents on the fate of pesticides. Adsorption and catalytic hydrolysis of carbaryl and atrazine on original biochars and deashed biochars were investigated. The two pesticides were substantially adsorbed by the biochars, with organic carbon normalized sorption coefficient (K oc ) values of 10 2.65 –10 3.66 L/kg for carbaryl and 10 1.90 –10 3.57 L/kg for atrazine at C e of 0.5 mg/L. Hydrophobic effect alone could not explain the sorption, and several other processes including pore-filling and π–π electron donor–acceptor interactions were involved in pesticide adsorption. Adsorption increased greatly on the deashed biochar, indicating that some organic sorption sites in the original biochars were blocked or difficult to access due to their interactions with inorganic moiety. The pesticides were found to hydrolyze faster in the presence of biochars, and in the presence of biochar pyrolyzed at 700 °C, carbaryl and atrazine were decomposed by 71.8% and 27.9% in 12 h, respectively. The elevated solution pH was the main reason for the enhanced hydrolysis; however both the mineral surface and dissolved metal ions released from the biochars were confirmed to catalyze the hydrolysis

Adsorption and catalytic hydrolysis of carbaryl and atrazine on pig manure-derived biochars: Impact of structural properties of biochars

Energy Technology Data Exchange (ETDEWEB)

Zhang, Peng, E-mail: phevos1983@yahoo.com.cn [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Sun, Hongwen, E-mail: sunhongwen@nankai.edu.cn [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Yu, Li [MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Sun, Tieheng [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China)

2013-01-15

Highlights: ► High ash content biochar can increase solution pH and released metal ions. ► Ash in biochar can combine pesticide through specific interactions. ► Composition and structure of biochar is favor for the hydrolysis of pesticides. -- Abstract: Biochars were produced from pig manure to elucidate the influence of biochars with high ash contents on the fate of pesticides. Adsorption and catalytic hydrolysis of carbaryl and atrazine on original biochars and deashed biochars were investigated. The two pesticides were substantially adsorbed by the biochars, with organic carbon normalized sorption coefficient (K{sub oc}) values of 10{sup 2.65}–10{sup 3.66} L/kg for carbaryl and 10{sup 1.90}–10{sup 3.57} L/kg for atrazine at C{sub e} of 0.5 mg/L. Hydrophobic effect alone could not explain the sorption, and several other processes including pore-filling and π–π electron donor–acceptor interactions were involved in pesticide adsorption. Adsorption increased greatly on the deashed biochar, indicating that some organic sorption sites in the original biochars were blocked or difficult to access due to their interactions with inorganic moiety. The pesticides were found to hydrolyze faster in the presence of biochars, and in the presence of biochar pyrolyzed at 700 °C, carbaryl and atrazine were decomposed by 71.8% and 27.9% in 12 h, respectively. The elevated solution pH was the main reason for the enhanced hydrolysis; however both the mineral surface and dissolved metal ions released from the biochars were confirmed to catalyze the hydrolysis.

Removal of priority pollutants from water by means of dielectric barrier discharge atmospheric plasma

Energy Technology Data Exchange (ETDEWEB)

Hijosa-Valsero, María, E-mail: mhijv@unileon.es [Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain); Molina, Ricardo, E-mail: ricardo.molina@cid.csic.es [Instituto de Química Avanzada de Cataluña (IQAC), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain); Schikora, Hendrik, E-mail: hendrik.schikora@igb.fraunhofer.de [Fraunhofer IGB, Nobelstraße 12, 70569 Stuttgart (Germany); Müller, Michael, E-mail: michael.mueller@igb.fraunhofer.de [Fraunhofer IGB, Nobelstraße 12, 70569 Stuttgart (Germany); Bayona, Josep M., E-mail: josep.bayona@cid.csic.es [Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), CID, CSIC, C/Jordi Girona 18-26, E-08034 Barcelona (Spain)

2013-11-15

Highlights: • DBD plasma reactors were used to remove pollutants from aqueous solutions. • Atrazine, chlorfenvinfos, 2,4-dibromophenol and lindane were studied. • First-order degradation kinetics were observed for all the compounds. • Degradation by-products were identified by GC–MS. • Treatment efficiencies were lower in industrial wastewater than in pure water. -- Abstract: Two different nonthermal plasma reactors at atmospheric pressure were assessed for the removal of organic micropollutants (atrazine, chlorfenvinfos, 2,4-dibromophenol, and lindane) from aqueous solutions (1–5 mg L{sup −1}) at laboratory scale. Both devices were dielectric barrier discharge (DBD) reactors; one was a conventional batch reactor (R1) and the other a coaxial thin-falling-water-film reactor (R2). A first-order degradation kinetics was proposed for both experiments. The kinetic constants (k) were slightly faster in R1 (0.534 min{sup −1} for atrazine; 0.567 min{sup −1} for chlorfenvinfos; 0.802 min{sup −1} for 2,4-dibromophenol; 0.389 min{sup −1} for lindane) than in R2 (0.104 min{sup −1} for atrazine; 0.523 min{sup −1} for chlorfenvinfos; 0.273 min{sup −1} for 2,4-dibromophenol; 0.294 min{sup −1} for lindane). However, energy efficiencies were about one order of magnitude higher in R2 (89 mg kW{sup −1} h{sup −1} for atrazine; 447 mg kW{sup −1} h{sup −1} for chlorfenvinfos; 47 mg kW{sup −1} h{sup −1} for 2,4-dibromophenol; 50 mg kW{sup −1} h{sup −1} for lindane) than in R1. Degradation by-products of all four compounds were identified in R1. As expected, when the plasma treatment (R1) was applied to industrial wastewater spiked with atrazine or lindane, micropollutant removal was also achieved, although at a lower rate than with aqueous solutions (k = 0.117 min{sup −1} for atrazine; k = 0.061 min{sup −1} for lindane)

Accelerated degradation of polyetheretherketone and its composites in the deep sea.

Science.gov (United States)

Liu, Hao; Wang, Jianzhang; Jiang, Pengfei; Yan, Fengyuan

2018-04-01

The performance of polymer composites in seawater, under high hydrostatic pressure (typically few tens of MPa), for simulating exposures at great depths in seas and oceans, has been little studied. In this paper, polyetheretherketone (PEEK) and its composites reinforced by carbon fibres and glass fibres were prepared. The seawater environment with different seawater hydrostatic pressure ranging from normal pressure to 40 MPa was simulated with special equipment, in which the seawater absorption and wear behaviour of PEEK and PEEK-based composites were examined in situ . The effects of seawater hydrostatic pressure on the mechanical properties, wear resistance and microstructure of PEEK and its composites were focused on. The results showed that seawater absorption of PEEK and its composites were greatly accelerated by increased hydrostatic pressure in the deep sea. Affected by seawater absorption, both for neat PEEK and composites, the degradation on mechanical properties, wear resistance and crystallinity were induced, the degree of which was increasingly serious with the increase of hydrostatic pressure of seawater environment. There existed a good correlation in an identical form of exponential function between the wear rate and the seawater hydrostatic pressure. Moreover, the corresponding mechanisms of the effects of deep-sea hydrostatic pressure were also discussed.

Production of isometric forces during sustained acceleration.

Science.gov (United States)

Sand, D P; Girgenrath, M; Bock, O; Pongratz, H

2003-06-01

The operation of high-performance aircraft requires pilots to apply finely graded forces on controls. Since they are often exposed to high levels of acceleration in flight, we investigated to what extent this ability is degraded in such an environment. Twelve healthy non-pilot volunteers were seated in the gondola of a centrifuge and their performance was tested at normal gravity (1 G) and while exposed to sustained forces of 1.5 G and 3 G oriented from head to foot (+Gz). Using an isometric joystick, they attempted to produce force vectors with specific lengths and directions commanded in random order by a visual display. Acceleration had substantial effects on the magnitude of produced force. Compared with 1 G, maximum produced force was about 2 N higher at 1.5 G and about 10 N higher at 3 G. The size of this effect was constant across the different magnitudes, but varied with the direction of the prescribed force. Acceleration degrades control of force production. This finding may indicate that the motor system misinterprets the unusual gravitoinertial environment and/or that proprioceptive feedback is degraded due to increased muscle tone. The production of excessive isometric force could affect the safe operation of high-performance aircraft.

Atrazine movement in a dark red latosol of the tropics Movimento da atrazina numa terra roxa estrutrada eutrófica

Directory of Open Access Journals (Sweden)

M.D. de Souza

1997-06-01

Full Text Available Atrazine displacement was studied in a soil profile as a function of water movement and time after herbicide application, taking into account possible influence of preferential flow on leaching. The experiment consisted of two 7 x 7m plots of a dark red latosol (Kanduidalfic Eutrudox, located at Piracicaba, SP, Brazil (22º 43'S and 47º 25'W, 250km inside continent, at an altitude of 580m. One plot was previously treated with 1,000 kg/ha of lime, in order to increase base saturation to 88%, and 500kg/ha of gypsum. Each plot was instrumented with tensiometers, neutron probe access tubes and soil solution extractors, in order to monitor water and atrazine flows. Atrazine was applied at the high rate of 6 kg/ha of active principle. Results showed intensive leaching of atrazine in the whole soil profile, up to the instrumented depth of 150cm, already ate the first sampling, seven days after herbicide application. The limed plot showed much higher atrazine leaching losses than the other plot. The atrazine adsorption capacity of the soil is very low, its maximum value being of the order of 10%, for the 0-15cm surface layer.O presente trabalho teve como objetivo verificar o deslocamento de atrazina no perfil do solo, em função do movimento da água e do tempo de aplicação, e possíveis influências de fluxos preferenciais sobre a lixiviação. O trabalho foi conduzido em uma Terra Roxa Estruturada eutrófica de textura argilosa, em Piracicaba (SP, no período de junho de 1992 a fevereiro de 1993. Foram instalados dois experimentos, sendo um com a cultura do milho irrigado (experimento 1 e o outro em solo nu (experimento 2. O experimento 1 foi instalado em uma área de 1000m² sobre a qual se demarcou duas parcelas de 12m x 12m separadas uma da outra por 18m. Uma parcela foi irrigada e a outra fertirrigada. O experimento 2 foi instalado em duas parcelas de 7m x 7m, separadas uma da outra por 5m. Em uma das parcelas do experimento 2 aplicou

Oral absorption and oxidative metabolism of atrazine in rats evaluated by physiological modeling approaches

International Nuclear Information System (INIS)

McMullin, Tami S.; Hanneman, William H.; Cranmer, Brian K.; Tessari, John D.; Andersen, Melvin E.

2007-01-01

Atrazine (ATRA) is metabolized by cytochrome P450s to the chlorinated metabolites, 2-chloro-4-ethylamino-6-amino-1,3,5-triazine (ETHYL), 2-chloro-4-amino-6-isopropylamino-1, 3, 5-triazine (ISO), and diaminochlorotriazine (DACT). Here, we develop a set of physiologically based pharmacokinetic (PBPK) models that describe the influence of oral absorption and oxidative metabolism on the blood time course curves of individual chlorotriazines (Cl-TRIs) in rat after oral dosing of ATRA. These models first incorporated in vitro metabolic parameters to describe time course plasma concentrations of DACT, ETHYL, and ISO after dosing with each compound. Parameters from each individual model were linked together into a final composite model in order to describe the time course of all 4 Cl-TRIs after ATRA dosing. Oral administration of ISO, ETHYL and ATRA produced double peaks of the compounds in plasma time courses that were described by multiple absorption phases from gut. An adequate description of the uptake and bioavailability of absorbed ATRA also required inclusion of additional oxidative metabolic clearance of ATRA to the mono-dealkylated metabolites occurring in GI a tract compartment. These complex processes regulating tissue dosimetry of atrazine and its chlorinated metabolites likely reflect limited compound solubility in the gut from dosing with an emulsion, and sequential absorption and metabolism along the GI tract at these high oral doses

Motor degradation prediction methods

Energy Technology Data Exchange (ETDEWEB)

Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

1996-12-01

Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor`s duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures.

Motor degradation prediction methods

International Nuclear Information System (INIS)

Arnold, J.R.; Kelly, J.F.; Delzingaro, M.J.

1996-01-01

Motor Operated Valve (MOV) squirrel cage AC motor rotors are susceptible to degradation under certain conditions. Premature failure can result due to high humidity/temperature environments, high running load conditions, extended periods at locked rotor conditions (i.e. > 15 seconds) or exceeding the motor's duty cycle by frequent starts or multiple valve stroking. Exposure to high heat and moisture due to packing leaks, pressure seal ring leakage or other causes can significantly accelerate the degradation. ComEd and Liberty Technologies have worked together to provide and validate a non-intrusive method using motor power diagnostics to evaluate MOV rotor condition and predict failure. These techniques have provided a quick, low radiation dose method to evaluate inaccessible motors, identify degradation and allow scheduled replacement of motors prior to catastrophic failures

Radiation damage calculations for the LANSCE degrader

International Nuclear Information System (INIS)

Ferguson, P.D.; Sommer, W.F.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Corzine, R.K.

1998-01-01

The A-6 water degrader at the Los Alamos Neutron Science Center (LANSCE) linear proton accelerator has an outer shell of Inconel 718. The degrader was irradiated by 800-MeV protons during 1988--1993 to an exposure of 5.3 ampere-hours (A h). As described in Ref. 1, material from the Inconel is currently being cut into specimens for microhardness, three-point bending, ball punch, microscopy, and corrosion tests. This paper is devoted to calculations of radiation damage, particularly displacement and He production, sustained by the degrader Inconel

The occurrence of glyphosate, atrazine, and other pesticides in vernal pools and adjacent streams in Washington, DC, Maryland, Iowa, and Wyoming, 2005-2006

Science.gov (United States)

Battaglin, William A.; Rice, Karen C.; Focazio, Michael J.; Salmons, Sue; Barry, Robert X.

2009-01-01

Vernal pools are sensitive environments that provide critical habitat for many species, including amphibians. These small water bodies are not always protected by pesticide label requirements for no-spray buffer zones, and the occurrence of pesticides in them is poorly documented. In this study, we investigated the occurrence of glyphosate, its primary degradation product aminomethylphosphonic acid, and additional pesticides in vernal pools and adjacent flowing waters. Most sampling sites were chosen to be in areas where glyphosate was being used either in production agriculture or for nonindigenous plant control. The four site locations were in otherwise protected areas (e.g., in a National Park). When possible, water samples were collected both before and after glyphosate application in 2005 and 2006. Twenty-eight pesticides or pesticide degradation products were detected in the study, and as many as 11 were identified in individual samples. Atrazine was detected most frequently and concentrations exceeded the freshwater aquatic life standard of 1.8 micrograms per liter (μg/l) in samples from Rands Ditch and Browns Ditch in DeSoto National Wildlife Refuge. Glyphosate was measured at the highest concentration (328 μg/l) in a sample from Riley Spring Pond in Rock Creek National Park. This concentration exceeded the freshwater aquatic life standard for glyphosate of 65 μg/l. Aminomethylphosphonic acid, triclopyr, and nicosulfuron also were detected at concentrations greater than 3.0 μg/l.

SSC accelerator availability allocation

International Nuclear Information System (INIS)

Dixon, K.T.; Franciscovich, J.

1991-03-01

Superconducting Super Collider (SSC) operational availability is an area of major concern, judged by the Central Design Group to present such risk that use of modern engineering tools would be essential to program success. Experience has shown that as accelerator beam availability falls below about 80%, efficiency of physics experiments degrades rapidly due to inability to maintain adequate coincident accelerator and detector operation. For this reason, the SSC availability goal has been set at 80%, even though the Fermi National Accelerator Laboratory accelerator, with a fraction of the SSC's complexity, has only recently approached that level. This paper describes the allocation of the top-level goal to part-level reliability and maintainability requirements, and it gives the results of parameter sensitivity studies designed to help identify the best approach to achieve the needed system availability within funding and schedule constraints. 1 ref., 12 figs., 4 tabs

Fate of the herbicides 2,4,5-T, atrazine, and DNOC in a shallow, anaerobic aquifer investigated by in situ passive diffusive emitters and laboratory batch experiments

DEFF Research Database (Denmark)

Arildskov, N.P.; Pedersen, Philip Grinder; Albrechtsen, Hans-Jørgen

2001-01-01

simultaneously with tritiated water (HTO) as tracer in the depth interval 3 to 4 rubs (meters below surface) by use of passive diffusive emitters. Atrazine and 2,4,5-T were persistent during the approximately 18 days residence time in the aquifer. In contrast, DNOC was rapidly removed from the water phase...... to 4 rubs and from 8 to 9 rubs. In these incubations, formation of Fe2+ and depletion of sulfate showed iron and sulfate reduction in sediment from 3 to 3.5 rubs and sulfate reduction in 3.5 to 4 rubs sediment. In sediment from 8 to 9 rubs, the dominant redox process was methane formation. In sediment...... first-order kinetics, and when normalized to the sediment/water-ratio, the field and laboratory derived rate constants compared well. The DNOC degradation in the methanogenic incubations (8 to 9 rubs) was up to 50 times faster than in the sediments from 3 to 4 rubs, likely due to the low redox potential....

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui, E-mail: sgzhou@soil.gd.cn

2015-08-15

Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH{sub 4} production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

Atrazine is primarily responsible for the toxicity of long-term exposure to a combination of atrazine and inorganic arsenic in the nigrostriatal system of the albino rat.

Science.gov (United States)

Bardullas, Ulises; Giordano, Magda; Rodríguez, Verónica Mireya

2013-01-01

Chronic and simultaneous exposure to a variety of chemicals present in the environment is an unavoidable fact. However, given the complexity of studying chemical mixtures, most toxicological studies have focused on the effects of short-term exposure to single substances. The aim of this study was to evaluate the effects on the nigrostriatal system of the chronic, simultaneous exposure to two widely distributed substances that have been identified as potential dopaminergic system toxicants, inorganic arsenic (iAs) and atrazine (ATR). Six groups of rats were treated daily for one year with atrazine (10mg ATR/kg), inorganic arsenic (0.5 or 50mgiAs/L of drinking water), or a combination of ATR+0.5mgiAs/L or ATR+50mgiAs/L. The 50mgiAs/L group showed locomotor hypoactivity, while all treatments decreased motor coordination in contrast no effects of treatment were found on the place and response learning tasks. Regarding markers for liver and muscle damage, there were no differences between groups in creatine kinase (CK) or aspartate transaminase (AST) activities, while decreases in lactate dehydrogenase (LDH) levels were found in some exposed groups. The striatal DA content was significantly reduced in ATR, 0.5mgiAs/L, ATR+0.5mgiAs/L, and ATR+50mgiAs/L groups, in comparison to the control group. The number of mesencephalic tyrosine hydroxylase positive cells decreased in the ATR and ATR+0.5mgiAs/L groups compared to the control. In contrast, immunoreactivity to cytochrome oxidase was reduced compared to the control in all treated groups, except for the group treated with 0.5iAsmg alone. Our results indicate that ATR has deleterious effects on dopaminergic neurons and that the combination of ATR and iAs does not exacerbate these effects. © 2013 Elsevier Inc. All rights reserved.

Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames

International Nuclear Information System (INIS)

Khan, Salman; Khan, Niaz Ali; Khan, M.K.

2014-01-01

The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scalar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for π-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. In the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. Interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of scalar fields is slower than for Dirac fields. (general)

Krylov Iterative Methods and the Degraded Effectiveness of Diffusion Synthetic Acceleration for Multidimensional SN Calculations in Problems with Material Discontinuities

International Nuclear Information System (INIS)

Warsa, James S.; Wareing, Todd A.; Morel, Jim E.

2004-01-01

A loss in the effectiveness of diffusion synthetic acceleration (DSA) schemes has been observed with certain S N discretizations on two-dimensional Cartesian grids in the presence of material discontinuities. We will present more evidence supporting the conjecture that DSA effectiveness will degrade for multidimensional problems with discontinuous total cross sections, regardless of the particular physical configuration or spatial discretization. Fourier analysis and numerical experiments help us identify a set of representative problems for which established DSA schemes are ineffective, focusing on diffusive problems for which DSA is most needed. We consider a lumped, linear discontinuous spatial discretization of the S N transport equation on three-dimensional, unstructured tetrahedral meshes and look at a fully consistent and a 'partially consistent' DSA method for this discretization. The effectiveness of both methods is shown to degrade significantly. A Fourier analysis of the fully consistent DSA scheme in the limit of decreasing cell optical thickness supports the view that the DSA itself is failing when material discontinuities are present in a problem. We show that a Krylov iterative method, preconditioned with DSA, is an effective remedy that can be used to efficiently compute solutions for this class of problems. We show that as a preconditioner to the Krylov method, a partially consistent DSA method is more than adequate. In fact, it is preferable to a fully consistent method because the partially consistent method is based on a continuous finite element discretization of the diffusion equation that can be solved relatively easily. The Krylov method can be implemented in terms of the original S N source iteration coding with only slight modification. Results from numerical experiments show that replacing source iteration with a preconditioned Krylov method can efficiently solve problems that are virtually intractable with accelerated source iteration

Research on degradation of vacuum O-rings under gamma radiation

CERN Document Server

Ino, H; Saitô, Y; Kubo, T; Kinsho, M

2003-01-01

The high-intensity proton accelerator being constructed by JAERI and KEK will generates greater beam power than conventional accelerators. The radiation emission due to beam losses will therefore increase. Since vacuum O-rings installed in the accelerator will be degraded badly by the radiation, there is need to find an O-ring that has more resistant to radiation. To find an O-ring that has better radiation resistant than that of the fluororubber used for conventional accelerators in general, some O-rings which are expected to have enough resistant to the radiation were irradiated, and estimated a degradation by measurement of outgassing rate, hardness, permeation time of helium gas, and an outward observation. Most of the O-rings were irradiated in an oxygen free atmosphere and in the air. The irradiations were carried out at room temperature in Co-60 gamma irradiation facility until a dose of 1 MGy was reached. The radiation resistance of PURE-RUBBER O-ring showed somewhat better than that of the fluororubb...

Accelerating the degradation of green plant waste with chemical decomposition agents.

Science.gov (United States)

Kejun, Sun; Juntao, Zhang; Ying, Chen; Zongwen, Liao; Lin, Ruan; Cong, Liu

2011-10-01

Degradation of green plant waste is often difficult, and excess maturity times are typically required. In this study, we used lignin, cellulose and hemicellulose assays; scanning electron microscopy; infrared spectrum analysis and X-ray diffraction analysis to investigate the effects of chemical decomposition agents on the lignocellulose content of green plant waste, its structure and major functional groups and the mechanism of accelerated degradation. Our results showed that adding chemical decomposition agents to Ficus microcarpa var. pusillifolia sawdust reduced the contents of lignin by 0.53%-11.48% and the contents of cellulose by 2.86%-7.71%, and increased the contents of hemicellulose by 2.92%-33.63% after 24 h. With increasing quantities of alkaline residue and sodium lignosulphonate, the lignin content decreased. Scanning electron microscopy showed that, after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, lignocellulose tube wall thickness increased significantlyIncreases of 29.41%, 3.53% and 34.71% were observed after treatment with NaOH, alkaline residue and sodium lignosulphonate, respectively. Infrared spectroscopy showed that CO and aromatic skeleton stretching absorption peaks were weakened and the C-H vibrational absorption peak from out-of-plane in positions 2 and 6 (S units) (890-900 cm(-1)) was strengthened after F. microcarpa var. pusillifolia sawdust was treated with chemical decomposition agents, indicating a reduction in lignin content. Several absorption peaks [i.e., C-H deformations (asymmetry in methyl groups, -CH(3)- and -CH(2)-) (1450-1460 cm(-1)); Aliphatic C-H stretching in methyl and phenol OH (1370-1380 cm(-1)); CO stretching (cellulose and hemicellulose) (1040-1060 cm(-1))] that indicate the presence of a chemical bond between lignin and cellulose was reduced, indicating that the chemical bond between lignin and cellulose had been partially broken. X-ray diffraction analysis showed that Na

Simulation and comparative study on the oxidation kinetics of atrazine by UV/H₂O₂, UV/HSO₅⁻ and UV/S₂O₈²⁻.

Science.gov (United States)

Luo, Congwei; Ma, Jun; Jiang, Jin; Liu, Yongze; Song, Yang; Yang, Yi; Guan, Yinghong; Wu, Daoji

2015-09-01

This study comparatively investigated atrazine (ATZ) degradation by irradiation at the wavelength of 254 nm in the presence of peroxides including hydrogen peroxide (H2O2), peroxymonosulfate (HSO5(-)), and persulfate (S2O8(2-)) at various initial ATZ concentrations and oxidant dosages. The effects of water matrix, such as carbonate/bicarbonate (HCO3(-)/CO3(2-)), chloride ions (Cl(-)), and natural organic matter (NOM), were evaluated on these three advanced oxidation processes. A simple steady-state kinetic model was developed based on the initial rates of ATZ destruction, which could well describe the apparent pseudo-first-order rate constants (k(app), s(-1)) of ATZ degradation in these three processes. The specific roles of reactive species (i.e., HO·, SO4(-·), CO3(-·), and Cl2(-·)) under various experimental conditions were quantitatively evaluated based on their steady-state concentrations obtained from this model. Modeling results showed that the steady-state concentrations of HO· and SO4(-·) decreased with the increase of CO3(2-)/HCO3(-) concentration, and the relative contribution of HO· to ATZ degradation significantly decreased in UV/H2O2 and UV/HSO5(-) systems. On the other hand, the scavenging effect of HCO3(-)/CO3(2-) on the relative contribution of SO4(-·) to ATZ degradation was lower than that on HO·. The presence of Cl(-) (0.5-10 mM) significantly scavenged SO4(-·) but had slightly scavenging effect on HO· at the present experimental pH, resulting in greater decrease of k(app) in the UV/S2O8(2-) than UV/H2O2 and UV/HSO5(-) systems. Higher levels of Cl2(-·) were generated in the UV/S2O8(2-) than those in the UV/H2O2 and UV/HSO5(-) systems at the same Cl(-) concentrations. NOM significantly decreased k(app) due to its effects of competitive UV absorption and radical scavenging with the latter one being dominant. These results improve the understanding of the effects of water constituents for ATZ degradation in the UV-based oxidation

Life estimation I and C cable insulation materials based on accelerated life testing accelerated life testing

International Nuclear Information System (INIS)

Santhosh, T.V.; Ramteke, P.K.; Shrestha, N.B.; Ahirwar, A.K.; Gopika, V.

2016-01-01

Accelerated Iife tests are becoming increasingly popular in today's industry due to the need for obtaining life data quickly and reliably. Life testing of products under higher stress levels without introducing additional failure modes can provide significant savings of both time and money. Correct analysis of data gathered via such accelerated life testing will yield parameters and other information for the product's life under use stress conditions. To be of practical use in assessing the operational behaviour of cables in NPPs, laboratory ageing aims to mimic the type of degradation observed under operational conditions. Conditions of testing therefore need to be carefully chosen to ensure that the degradation mechanism occurring in the accelerated tests are similar to those which occur in service. This paper presents the results of an investigation in which the elongation-at-break (EAB) measurements were carried on a typical control cable to predict the mean life at service conditions. A low voltage polyvinyl chloride (PVC) insulated and PVC sheathed control cable, used in NPP instrumentation and control (I and C) applications, was subjected thermal ageing at three elevated temperatures

Catalyst Degradation Under Potential Cycling as an Accelerated Stress Test for PBI-Based High-Temperature PEM Fuel Cells - Effect of Humidification

DEFF Research Database (Denmark)

Søndergaard, Tonny; Cleemann, Lars Nilausen; Zhong, Lijie

2018-01-01

In the present work, high-temperature polymer electrolyte membrane fuel cells were subjected to accelerated stress tests of 30,000 potential cycles between 0.6 and 1.0 V at 160 textdegreeC (133 h cycling time). The effect that humidity has on the catalyst durability was studied by testing either...... with or without humidification of the nitrogen that was used as cathode gas during cycling segments. Pronounced degradation was seen from the polarization curves in both cases, though permanent only in the humidified case. In the unhumidified case, the performance loss was more or less recoverable following 24 h...

Using Uncertainty Analysis to Guide the Development of Accelerated Stress Tests (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Kempe, M.

2014-03-01

Extrapolation of accelerated testing to the long-term results expected in the field has uncertainty associated with the acceleration factors and the range of possible stresses in the field. When multiple stresses (such as temperature and humidity) can be used to increase the acceleration, the uncertainty may be reduced according to which stress factors are used to accelerate the degradation.

Effective sorption of atrazine by biochar colloids and residues derived from different pyrolysis temperatures.

Science.gov (United States)

Yang, Fan; Gao, Yan; Sun, Lili; Zhang, Shuaishuai; Li, Jiaojiao; Zhang, Ying

2018-04-26

Biochar has attracted much attention, which owns many environmental and agronomic benefits, including carbon sequestration, improvement of soil quality, and immobilization of environmental contaminants. Biochar has been also investigated as an effective sorbent in recent publications. Generally, biochar particles can be divided into colloids and residues according to particle sizes, while understanding of adsorption capacities towards organic pollutants in each section is largely unknown, representing a critical knowledge gap in evaluations on the effectiveness of biochar for water treatment application. Scanning electron microscopy (SEM) images, X-ray diffraction (XRD), Raman spectra, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) method are used to examine the structures and surface properties of biochar colloids and residues derived from corn straws prepared at different pyrolysis temperatures. Also, their roles in atrazine (a typical organic pollutant) removal are investigated by batch adsorption experiments and fitted by different kinetic and thermodynamic models, respectively. The adsorption capacities of biochar colloids are much more than those of residues, resulting from the colloids containing abundant oxygen functional groups and mineral substances, and the adsorption capacities of biochar colloids and residues increase with the increase of pyrolysis temperatures. The highest adsorption performance of 139.33 mg g -1 can be obtained in biochar colloids prepared at 700 °C, suggesting the important functions of biochar colloids in the application of atrazine removal by biochar.

Does area deprivation modify the association between exposure to a nitrate and low-dose atrazine metabolite mixture in drinking water and small for gestational age? A historic cohort study.

Science.gov (United States)

Limousi, F; Albouy-Llaty, M; Carles, C; Dupuis, A; Rabouan, S; Migeot, V

2014-04-01

Birth weight may be influenced by environmental and socio-economic factors that could interact. The main objective of our research was to investigate whether area deprivation may modify the association between drinking water exposure to a mixture of atrazine metabolites and nitrates during the second trimester of pregnancy and prevalence of small for gestational age (SGA) neonates. We conducted a historic cohort study in Deux-Sèvres, France between 2005 and 2010, using birth records, population census and regularly performed drinking water withdrawals at community water systems. Exposure to an atrazine metabolite/nitrate mixture in drinking water was divided into six classes according to the presence or absence of atrazine metabolites and to the terciles of nitrate concentrations in each trimester of pregnancy. We used a logistic regression to model the association between SGA and mixture exposure at the second trimester while taking into account the area deprivation measured by the Townsend index as an effect modifier and controlling for the usual confounders. We included 10,784 woman-neonate couples. The risk of SGA when exposed to second tercile of nitrate without atrazine metabolites was significantly greater in women living in less deprived areas (OR = 2.99; 95 % CI (1.14, 7.89)), whereas it was not significant in moderately and more deprived areas. One of the arguments used to explain this result is the presence of competing risk factors in poorer districts.

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

Science.gov (United States)

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

Effects of the Atrazine herbicide over the diazotrophic microorganisms associated with corn in a Saldana soil (Tolima)

International Nuclear Information System (INIS)

Ordonez, Alba R; Lozano de Yunda, A; Fuentes, C

1999-01-01

In this study, it was evaluated, at greenhouse in soil pots, the effect of the herbicide atrazine in different dose (corresponding to o, 0.75, 1.5 and 3.0 kg of soil hectare) over time (15, 30, 45, 60 and 90 days after the application) on the diazotrophic micro-organisms associated with rhizosphere soil and root of a corn cultivation in a clay loam soil of Saldana - Tolima. It was determined the population of diazotrophic microorganisms in soil by the most probable number technique; also it was observed the characteristic growth in the specific cultivation semisolid Nfb-malic acid medium and was evaluated the nitrogenase activity by means of the acetylene reduction technique. Of the same form, it was observed the characteristic growth and it was evaluated the nitrogenase activity of direct fragment sowings of root in the Nfb-malic acid medium. The 60.8% of soil isolates presented characteristic cultural growth in the form of whitish pellicle under the surface of the medium. in the root 83.3% showed this type of growth. The population of diazotrophic microorganisms of soil did not present significant differences (α = 0.05) between treatments neither over time the nitrogenase activity of soil dilutions demonstrated that there is no a significant effect (α = 0.05) of the treatments (dose) but if there is significant effect of the time. The highest values were presented to 45 days of application of the herbicide, with the application of the highest dose. the nitrogenase activity in the root to what is long of the time was different from rhizosphere soil. The treatment without application of atrazine presented greater values to what is long of the time, however, also in this case were not presented significant differences (α = 0.05) between the treatments (dose) neither to what is long of the time. For so much, as a conclusion, they were not presented effects on the population and the nitrogenase activity of the diazotrophic microorganisms until 90 days of after the

Assessment of organochlorine pesticides and atrazine residues in Maize Produced in Ghana using GC-ECD/ GC-MS

International Nuclear Information System (INIS)

Miensah, E.D.

2015-07-01

Maize is consumed by over 95% of the Ghanaian populace and the practice of using atrazine, lindane and other organochlorine pesticides in its production has raised concerns about potential adverse effects on human health and the environment. A field survey was conducted in this study to assess farmers’ knowledge of safe handling and use of these chemicals as well as toxicity awareness and symptoms among farmers and traders. Residues of the pesticides in maize samples as well as the potential health risk associated with exposure to them were also evaluated. Data obtained from the field survey indicate that a large proportion of farmers are at risk of pesticide poisoning through occupational exposure. Over 80 % of applicators do not apply safety precautions during pesticide mixing and application; resulting in considerable prevalence of pesticide related illnesses in the study area. Residues of lindane and atrazine were below detection limits of 0.005 mg/kg and 0.010 mg/kg respectively of the GC-ECD/MS used for the analysis; except in the Ashanti region where atrazine was 0.05 mg/kg which is within the EU-MRL of 0.1 mg/kg. However, minute concentrations of other organochlorines (endrin- 0.007 mg/kg; heptachlor- 0.023 mg/kg; alpha-endosulfan- 0.013 mg/kg) were found in maize samples from Brong Ahafo, Eastern, Central and Upper west regions. Though endrin and alpha-endosulfan were below the EU-MRL of 0.01 mg/kg and 0.10 mg/kg respectively, heptachlor was slightly above the EU-MRL of 0.01 mg/kg. The estimated doses for all these other organochlorines pesticides do not pose direct hazard to human health because their estimated dose values were lower than toxic thresholds and reference doses. However, due to the unsafe application practices by applicators, there exists a potential risk for systemic and carcinogenic health effects by these chemicals in the study area. (au)

Abiotic degradation of plastic films

Science.gov (United States)

Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

2017-01-01

Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

A Discussion of Water Pollution in the United States and Mexico; with High School Laboratory Activities for Analysis of Lead, Atrazine, and Nitrate.

Science.gov (United States)

Kelter, Paul B.; Grundman, Julie; Hage, David S.; Carr, James D.; Castro-Acuna, Carlos Mauricio

1997-01-01

Presents discussions on sources, health impacts, methods of analysis as well as lengthy discussions of lead, nitrates, and atrazine as related to water pollution and the interdisciplinary nature of the modern chemistry curriculum. (DKM)

Sorption and leaching potential of isoproturon and atrazine in low organic carbon soil of Pakistan under a wheat-maize rotation

Science.gov (United States)

Limited data are available on the sorption and leaching of pesticides in agricultural soils of Pakistan with low soil organic carbon (OC). Sorption potential of two widely used pesticides, isoproturon and atrazine, was determined using the batch equilibration method on soils from 0-35 cm, 35-70 and ...

Accelerating Rate Calorimetry Tests of Lithium-Ion Cells Before and After Storage Degradation at High Temperature

Directory of Open Access Journals (Sweden)

Mendoza-Hernandez Omar Samuel

2017-01-01

Full Text Available Understanding the behavior of Li-ion cells during thermal runaway is critical to evaluate the safety of these energy storage devices under outstanding conditions. Li-ion cells possess a high energy density and are used to store and supply energy to many aerospace applications. Incidents related to the overheating or thermal runaway of these cells can cause catastrophic damages that could end up costly space missions; therefore, thermal studies of Li-ion cells are very important for ensuring safety and reliability of space missions. This work evaluates the thermal behavior of Li-ion cells before and after storage degradation at high temperature using accelerating rate calorimeter (ARC equipment to analyze the thermal behavior of Li-ion cells under adiabatic conditions. Onset temperature points of self-heating and thermal runaway reactions are obtained. The onset points are used to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge. The results obtained can be useful to develop accurate thermo-electrochemical models of Li-ion cells.

High-power UV-LED degradation: Continuous and cycled working condition influence

Science.gov (United States)

Arques-Orobon, F. J.; Nuñez, N.; Vazquez, M.; Segura-Antunez, C.; González-Posadas, V.

2015-09-01

High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated life tests are developed to evaluate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated life test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

Leaching and degradation of corn and soybean pesticides in an Oxisol of the Brazilian Cerrados.

Science.gov (United States)

Laabs, V; Amelung, W; Pinto, A; Altstaedt, A; Zech, W

2000-11-01

Pesticide pollution of ground and surface water is of growing concern in tropical countries. The objective of this pilot study was to evaluate the leaching potential of eight pesticides in a Brazilian Oxisol. In a field experiment near Cuiabá, Mato Grosso, atrazine, chlorpyrifos, lambda-cyhalothrin, endosulfane alpha, metolachlor, monocrotofos, simazine, and trifluraline were applied onto a Typic Haplustox. Dissipation in the topsoil, mobility within the soil profile and leaching of pesticides were studied for a period of 28 days after application. The dissipation half-life of pesticides in the topsoil ranged from 0.9 to 14 d for trifluraline and metolachlor, respectively. Dissipation curves were described by exponential functions for polar pesticides (atrazine, metolachlor, monocrotofos, simazine) and bi-exponential ones for apolar substances (chlorpyrifos, lambda-cyhalothrin, endosulfane alpha, trifluraline). Atrazine, simazine and metolachlor were moderately leached beyond 15 cm soil depth, whereas all other compounds remained within the top 15 cm of the soil. In lysimeter percolates (at 35 cm soil depth), 0.8-2.0% of the applied amounts of atrazine, simazine, and metolachlor were measured within 28 days after application. Of the other compounds less than 0.03% of the applied amounts was detected in the soil water percolates. The relative contamination potentials of pesticides, according to the lysimeter study, were ranked as follows: metolachlor > atrazine = simazine > monocrotofos > endsulfane alpha > chlorpyrifos > trifluraline > lambda-cyhalothrin. This order of the pesticides was also achieved by ranking them according to their effective sorption coefficient Ke, which is the ratio of Koc to field-dissipation half-life.

Critical analysis of industrial electron accelerators

Energy Technology Data Exchange (ETDEWEB)

Korenev, S. E-mail: sergey_korenev@steris.com

2004-10-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterilization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed.

Critical analysis of industrial electron accelerators

Science.gov (United States)

Korenev, S.

2004-09-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterlization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed.

Critical analysis of industrial electron accelerators

International Nuclear Information System (INIS)

Korenev, S.

2004-01-01

The critical analysis of electron linacs for industrial applications (degradation of PTFE, curing of composites, modification of materials, sterilization and others) is considered in this report. Main physical requirements for industrial electron accelerators consist in the variations of beam parameters, such as kinetic energy and beam power. Questions for regulation of these beam parameters are considered. The level of absorbed dose in the irradiated product and throughput determines the main parameters of electron accelerator. The type of ideal electron linac for industrial applications is discussed

Atrazine analysis using an amperometric immunosensor based on single-chain antibody fragments and regeneration-free multi-calibrant measurement

International Nuclear Information System (INIS)

Grennan, Kathleen; Strachan, Gillian; Porter, Andrew J.; Killard, Anthony J.; Smyth, Malcolm R.

2003-01-01

This work describes the development of an electrochemical immunosensor for the analysis of atrazine using recombinant single-chain antibody (scAb) fragments. The sensors are based on carbon paste screen-printed electrodes incorporating the conducting polymer polyaniline (PANI)/poly(vinylsulphonic acid) (PVSA), which enables direct mediatorless coupling to take place between the redox centres of antigen-labelled horseradish peroxidase (HRP) and the electrode surface. Competitive immunoassays can be performed in real-time using this separation-free system. Analytical measurements based on the pseudo-linear relationship between the slope of a real-time amperometric signal and the concentration of analyte, yield a novel immunosensor set-up capable of regenerationless amperometric analysis. Multiple, sequential measurements of standards and samples can be performed on a single scAb-modified surface in a matter of minutes. No separation of bound and unbound species was necessary prior to detection. The system is capable of measuring atrazine to a detection limit of 0.1 ppb (0.1 μg l -1 ). This system offers the potential for rapid, cost-effective immunosensing for the analysis of samples of environmental, medical and pharmaceutical significance

Accelerated thermal and radiative ageing of hydrogenated NBR for DRC

International Nuclear Information System (INIS)

Mares, G.; Notingher, P.

1996-01-01

The accelerated thermal and gamma radiation ageing of HNBR carbon black-T80 has been studied by measuring the residual deformation under constant deflection -- DRC, in air, using a relevant equation for the relaxation phenomena. The residual deformation under constant deflection during the process of accelerated ageing is increasing but the structure of polymer answers in the proper manner to the mechanical stress. The degradation equations were obtained, using Alfrey model for the relaxation polymer subject to compression and an Arrhenius dependence for the chemical reaction rate. The inverted relaxation time for the thermal degradation is depending on the chemical reaction rate and the dose rate of gamma radiation

Degradation properties of the electrostatic assembly PDLLA/CS/CHS nerve conduit

Energy Technology Data Exchange (ETDEWEB)

Xu Haixing [School of Chemical Engineering, Wuhan University of Technology, Wuhan 430070 (China); Yan Yuhua; Wan Tao; Li Shipu, E-mail: yanyuhua8@126.co [Biomedical Materials and Engineering Research Center, Wuhan University of Technology, Wuhan 430070 (China)

2009-08-15

A poly(d,l-lactic acid)/chondroitin sulfate/chitosan (PDLLA/CS/CHS) nerve conduit for repairing nerve defects was prepared by electrostatic assembly and the thermally induced phase separation technique. The hydrophilic characteristics of the PDLLA/CS/CHS assembly nerve conduits were improved markedly. The degradation behavior of the nerve conduit with various assembly layers was evaluated by a pH change, weight loss rate and molecular weight change. The pH of the solution of the nerve conduit could be effectively adjusted by varying the layer numbers and overcoming the acidity-caused auto-acceleration of PDLLA; the nerve conduit can retain its integrity in a phosphate buffer solution after being degraded for 3 months. After such a conduit was implanted in the rat for 3 months, obvious degradation occurred, but the regenerated nerve was integrated and it grew successfully from the proximal to distal nerve stump. All these results implied that the degradation rate of the prepared conduit can adapt to the regeneration of the peripheral nerve, which might be a new derivative of PDLLA-based biodegradable materials for repairing nerve injuries without acidity-caused irritations and acidity-induced auto-accelerating degradation behavior as shown by PDLLA.

Degradation characteristics of 2,4-dichlorophenoxyacetic acid in electro-biological system

Energy Technology Data Exchange (ETDEWEB)

Zhang, JingLi, E-mail: jinglizhangczp@126.com [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Cao, ZhanPing; Zhang, HongWei [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Zhao, LianMei [Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Sun, XuDong; Mei, Feng [School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

2013-11-15

Highlights: • The 2,4-D reductive degradation was studied in an electro-biological system. • The electric auxiliary accelerates 2,4-D microbial degradation. • A electron transfer is achieved between the electrode, bacteria and the pollutants. • The paper provides a promising way for the degradation of persistent organics. -- Abstract: The reductive degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in an electro-biological system, a biological system and an electric catalytic system, respectively. Electrochemical characteristics were monitored by cyclic voltammetry and the intermediate products of 2,4-D degradation were determined by high speed liquid chromatography (HPLC). The results showed that all 2,4-D degradations in the three systems conformed to the kinetics characteristics of one-order reaction, and the degradation kinetics constants were 28.74 × 10{sup −2} h{sup −1}, 19.73 × 10{sup −2} h{sup −1} and 3.54 × 10{sup −2} h{sup −1}, respectively. The kinetics constant in the electro-biological system was higher than the sum in the other two systems by 19%. The electrochemical assistance provided the electrons and accelerated the electron transfer rate in the microbial degradation of 2,4-D. The degradation resulted from the microbial reduction strengthened by the electrochemical assistance. The electron transfer existed between the electrode, cytochrome, NAD and the pollutants. A long-range electron transfer process could be achieved on the multi-phase interfaces between the electrode, bacteria and the pollutants.

The relationship between study sponsorship, risks of bias, and research outcomes in atrazine exposure studies conducted in non-human animals: Systematic review and meta-analysis.

Science.gov (United States)

Bero, L; Anglemyer, A; Vesterinen, H; Krauth, D

2016-01-01

A critical component of systematic review methodology is the assessment of the risks of bias of studies that are included in the review. There is controversy about whether funding source should be included in a risk of bias assessment of animal toxicology studies. To determine whether industry research sponsorship is associated with methodological biases, the results, or conclusions of animal studies examining the effect of exposure to atrazine on reproductive or developmental outcomes. We searched multiple electronic databases and the reference lists of relevant articles to identify original research studies examining the effect of any dose of atrazine exposure at any life stage on reproduction or development in non-human animals. We compared methodological risks of bias, the conclusions of the studies, the statistical significance of the findings, and the magnitude of effect estimates between industry sponsored and non-industry sponsored studies. Fifty-one studies met the inclusion criteria. There were no differences in methodological risks of bias in industry versus non-industry sponsored studies. 39 studies tested environmentally relevant concentrations of atrazine (11 industry sponsored, 24 non-industry sponsored, 4 with no funding disclosures). Non-industry sponsored studies (12/24, 50.0%) were more likely to conclude that atrazine was harmful compared to industry sponsored studies (2/11, 18.1%) (p value=0.07). A higher proportion of non-industry sponsored studies reported statistically significant harmful effects (8/24, 33.3%) compared to industry-sponsored studies (1/11; 9.1%) (p value=0.13). The association of industry sponsorship with decreased effect sizes for harm outcomes was inconclusive. Our findings support the inclusion of research sponsorship as a risk of bias criterion in tools used to assess risks of bias in animal studies for systematic reviews. The reporting of other empirically based risk of bias criteria for animal studies, such as blinded

Effects of prenatal exposure to a low dose atrazine metabolite mixture on pubertal timing and prostate development of male Long-Evans rats

Energy Technology Data Exchange (ETDEWEB)

Stanko, Jason [National Institute of Environmental Health Sciences (NIEHS); Enoch, Rolondo [North Carolina Central University, Durham; Rayner, Jennifer L [ORNL; Davis, Christine [U.S. Environmental Protection Agency; Wolf, Douglas [U.S. Environmental Protection Agency; Malarkey, David [University of North Carolina, Chapel Hill; Fenton, Suzanne [National Institute of Environmental Health Sciences (NIEHS)

2010-12-01

The present study examines the postnatal reproductive development of male rats following prenatal exposure to an atrazine metabolite mixture (AMM) consisting of the herbicide atrazine and its environmental metabolites diaminochlorotriazine, hydroxyatrazine, deethylatrazine, and deisopropylatrazine. Pregnant Long-Evans rats were treated by gavage with 0.09, 0.87, or 8.73 mg AMM/kg body weight (BW), vehicle, or 100 mg ATR/kg BW positive control, on gestation days 15 19. Preputial separation was significantly delayed in 0.87 mg and 8.73 mg AMM-exposed males. AMM-exposed males demonstrated a significant treatment-related increase in incidence and severity of inflammation in the prostate on postnatal day (PND) 120. A dose-dependent increase in epididymal fat masses and prostate foci were grossly visible in AMM-exposed offspring. These results indicate that a short, late prenatal exposure to mixture of chlorotriazine metabolites can cause chronic prostatitis in male LE rats. The mode of action for these effects is presently unclear.

Evaluation of the electrode performance for PAFC by using acid absorption, acceleration and ac-impedance measurement

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Soo; Song, Rak-Hyun; Choi, Byung-Woo [Korea Institute of Energy Research, Taejon (Korea, Republic of)] [and others

1996-12-31

In PAFC, the degradation on cathode electrode caused by carbon corrosion, platinum dissolution and growth is especially severe. An acceleration test is a good technique for evaluating the degradation of electrode performance, because it does not need long time. Coleman et al used thermal cycling and on-off cycling as an acceleration test. Song et al showed that hydrogen shortage decreased the electrode performance more rapidly than that of air shortage in gas shortage test. Honji et al reported that the rate of coarsening of Pt particle is rapid in open circuit potential and this is one of major causes on the performance degradation of electrode. The cathode performance has been studied by using acid absorption, acceleration and ac-impedance measurements as functions of the polytetrafluoroethylene (PTFE) contents and sintering temperatures of the electrode.

The removal of COD and NH3-N from atrazine production wastewater treatment using UV/O3: experimental investigation and kinetic modeling.

Science.gov (United States)

Jing, Liang; Chen, Bing; Wen, Diya; Zheng, Jisi; Zhang, Baiyu

2018-01-01

In this study, a UV/O 3 hybrid advanced oxidation system was used to remove chemical oxygen demand (COD), ammonia nitrogen (NH 3 -N), and atrazine (ATZ) from ATZ production wastewater. The removal of COD and NH 3 -N, under different UV and O 3 conditions, was found to follow pseudo-first-order kinetics with rate constants ranging from 0.0001-0.0048 and 0.0015-0.0056 min -1 , respectively. The removal efficiency of ATZ was over 95% after 180 min treatment, regardless the level of UV power. A kinetic model was further proposed to simulate the removal processes and to quantify the individual roles and contributions of photolysis, direct O 3 oxidation, and hydroxyl radical (OH·) induced oxidation. The experimental and kinetic modeling results agreed reasonably well with deviations of 12.2 and 13.1% for the removal of COD and NH 3 -N, respectively. Photolysis contributed appreciably to the degradation of ATZ, while OH· played a dominant role for the removal of both COD and NH 3 -N, especially in alkaline environments. This study provides insights into the treatment of ATZ containing wastewater using UV/O 3 and broadens the knowledge of kinetics of ozone-based advanced oxidation processes.

Functional and RNA-sequencing analysis revealed expression of a novel stay-green gene from Zoysia japonica (ZjSGR caused chlorophyll degradation and accelerated senescence in Arabidopsis

Directory of Open Access Journals (Sweden)

Ke Teng

2016-12-01

Full Text Available Senescence is not only an important developmental process, but also a responsive regulation to abiotic and biotic stress for plants. Stay-green protein plays crucial roles in plant senescence and chlorophyll degradation. However, the underlying mechanisms were not well studied, particularly in non-model plants. In this study, a novel stay-green gene, ZjSGR, was isolated from Zoysia japonica. Subcellular localization result demonstrated that ZjSGR was localized in the chloroplasts. Quantitative real-time PCR results together with promoter activity determination using transgenic Arabidopsis confirmed that ZjSGR could be induced by darkness, ABA and MeJA. Its expression levels could also be up-regulated by natural senescence, but suppressed by SA treatments. Overexpression of ZjSGR in Arabidopsis resulted in a rapid yellowing phenotype; complementary experiments proved that ZjSGR was a functional homologue of AtNYE1 from Arabidopsis thaliana. Overexpression of ZjSGR accelerated chlorophyll degradation and impaired photosynthesis in Arabidopsis. Transmission electron microscopy observation revealed that overexpression of ZjSGR decomposed the chloroplasts structure. RNA sequencing analysis showed that ZjSGR could play multiple roles in senescence and chlorophyll degradation by regulating hormone signal transduction and the expression of a large number of senescence and environmental stress related genes. Our study provides a better understanding of the roles of SGRs, and new insight into the senescence and chlorophyll degradation mechanisms in plants.

Atrazine Concentrations in Stream Water and Streambed Sediment Pore Water in the St. Joseph and Galien River Basins, Michigan and Indiana, May 2001 - September 2003

National Research Council Canada - National Science Library

Duris, Joseph W; Reeves, Howard W; Kiesler, James L

2004-01-01

The U.S. Geological Survey (USGS) sampled multiple stream sites across the St. Joseph and Galien River Basins to detect and quantify the herbicide atrazine using a field enzyme-linked immunosorbent assay (ELISA) triazine test...

Radiation degradation of silk protein

International Nuclear Information System (INIS)

Pewlong, W.; Sudatis, B.; Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu

2000-01-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl 2 /C 2 H 5 OH/H 2 O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

Radiation degradation of silk protein

Energy Technology Data Exchange (ETDEWEB)

Pewlong, W; Sudatis, B [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-03-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated using an electron beam accelerator to investigate the application of the radiation degradation technique as a means to solubilize fibroin. The irradiation caused a significant degradation of the fiber. The tensile strength of fibroin fiber irradiated up to 2500 kGy decreased rapidly with increasing dose. The presence of oxygen in the irradiation atmosphere enhanced degradation of the tensile strength. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: a calcium chloride solution(CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O=1:2:8 in mole ratio), a hydrochloric acid (0.5 N) and a distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water soluble proteins was extracted by a distilled water. (author)

A Theoretical Model for Metal Corrosion Degradation

Directory of Open Access Journals (Sweden)

David V. Svintradze

2010-01-01

Full Text Available Many aluminum and stainless steel alloys contain thin oxide layers on the metal surface which greatly reduce the corrosion rate. Pitting corrosion, a result of localized breakdown of such films, results in accelerated dissolution of the underlying metal through pits. Many researchers have studied pitting corrosion for several decades and the exact governing equation for corrosion pit degradation has not been obtained. In this study, the governing equation for corrosion degradation due to pitting corrosion behavior was derived from solid-state physics and some solutions and simulations are presented and discussed.

The impact of external optical feedback on the degradation behavior of high-power diode lasers

DEFF Research Database (Denmark)

Hempel, Martin; Chi, Mingjun; Petersen, Paul Michael

2013-01-01

The impact of external feedback on high-power diode laser degradation is studied. For this purpose early stages of gradual degradation are prepared by accelerated aging of 808-nm-emitting AlGaAs-based devices. While the quantum well that actually experiences the highest total optical load remains...... unaffected, severe impact is observed to the cladding layers and the waveguide. Consequently hardening of diode lasers for operation under external optical feedback must necessarily involve claddings and waveguide, into which the quantum well is embedded.......The impact of external feedback on high-power diode laser degradation is studied. For this purpose early stages of gradual degradation are prepared by accelerated aging of 808-nm-emitting AlGaAs-based devices. While the quantum well that actually experiences the highest total optical load remains...

In-situ co-doping of sputter-deposited TiO2:WN films for the development of photoanodes intended for visible-light electro-photocatalytic degradation of emerging pollutants

Science.gov (United States)

Delegan, N.; Pandiyan, R.; Komtchou, S.; Dirany, A.; Drogui, P.; El Khakani, M. A.

2018-05-01

We report on the magnetron sputtering deposition of in-situ codoped TiO2:WN films intended for electro-photocatalytic (EPC) applications under solar irradiation. By varying the RF-magnetron sputtering deposition parameters, we were able to tune the in-situ incorporation of both N and W dopants in the TiO2 films over a wide concentration range (i.e., 0-9 at. % for N and 0-3 at. % for W). X-ray photoelectron spectroscopy analysis revealed that both dopants are mostly of a substitutional nature. The analysis of the UV-Vis transmission spectra of the films confirmed that the optical bandgap of both TiO2:N and TiO2:WN films can be significantly narrowed (from 3.2 eV for undoped-TiO2 down to ˜2.3 eV for the doped ones) by tuning their dopant concentrations. We were thus able to pinpoint an optimal window for both dopants (N and W) where the TiO2:WN films exhibit the narrowest bandgap. Moreover, the optimal codoping conditions greatly reduce the recombination defect state density compared to the monodoped TiO2:N films. These electronically passivated TiO2:WN films are shown to be highly effective for the EPC degradation of atrazine (pesticide pollutant) under sunlight irradiation (93% atrazine degraded after only 30 min of EPC treatment). Indeed, the optimally codoped TiO2:WN photoanodes were found to be more efficient than both the undoped-TiO2 and equally photosensitized TiO2:N photoanodes (by ˜70% and ˜25%, respectively) under AM1.5 irradiation.

New Method to Characterize Degradation of First Surface Aluminum Reflectors: Preprint

Energy Technology Data Exchange (ETDEWEB)

Sutter, F.; Heller, P.; Meyen, S.; Pitz-Paal, R.; Kennedy, C.; Fernandez-Garcia, A.; Schmucker, M.

2010-10-01

This paper reports the development of a new optical instrument capable of characterizing the aging process of enhanced first surface aluminum reflectors for concentrating solar power (CSP) application. Samples were exposed outdoors at different sites and in accelerated exposure tests. All samples exposed outdoors showed localized corrosion spots. Degradation originated from points of damage in the protective coating, but propagated underneath the protective coating. The degraded samples were analyzed with a microscope and with a newly designed space-resolved specular reflectometer (SR)2 that is capable of optically detecting and characterizing the corrosion spots. The device measures the specular reflectance at three acceptance angles and the wavelengths with spatial resolution using a digital camera's CMOS sensor. It can be used to measure the corrosion growth rate during outdoor and accelerated exposure tests. These results will allow a correlation between the degraded mirror surface and its specular reflectance.

Radiation-thermal transformation of degraded oils

International Nuclear Information System (INIS)

Guliyeva, N.G.; Aliyeva, S.F.

2010-01-01

Full text :In order to elucidate the role of radiation in the process of oil degradation in the environment, and to identify opportunities for application of radiation-chemical technology to clean oil-contaminated soil were studied some regularities of radiation-chemical transformations of oil samples taken from wells, as well as after long-term presence on the surface of the water and soil. The most high radiation resistances of oil are samples taken from surface water. This is due to structural changes in the process of oil degradation, namely an increase in their part of the radiation-resistant resins and aspartames. This is due to evaporation of light hydrocarbons and heavy destructive transformations under the influence of oxygen, microorganisms, as well as components of the surface layer of soil. This phenomenon is explained by the specificity of action of the beam of accelerated electrons, namely the possible heating of the reaction zone due to inhibition of the electron. In this case the acceleration of diffusion processes results in an increase in the yield of gases.

Bidirectional impact of atrazine-induced elevations in progesterone (P4) on the LH surge in the ovariectomized, estradiol (E2)-primed rat

Science.gov (United States)

Multiple daily exposures to the herbicide atrazine (ATZ) have been reported to suppress the luteinizing hormone surge (LHS) in female rats. Exposure has also been found to elevate P4 concentrations, and an increase in P4 is known to have a different directional effect on LH depe...

Atrazine transport within a coastal zone in Southeastern Puerto Rico: a sensitivity analysis of an agricultural field model and riparian zone management model

Science.gov (United States)

Water quality models are used to predict effects of conservation practices to mitigate the transport of herbicides to water bodies. We used two models - the Agricultural Policy/Environmental eXtender (APEX) and the Riparian Ecosystem Management Model (REMM) to predict the movement of atrazine from ...

Degradation of polyethylene induced by plasma in oxidizing atmospheres

International Nuclear Information System (INIS)

Colin, E.; Olayo, M.G.; Cruz, G.J.

2002-01-01

The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries: Distribution, transport and fate

Science.gov (United States)

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.; ,

1992-01-01

The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6'-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be < 2% of the annual application of each herbicide in the Midwest.The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2???,6???-diethylacetanilide, 2-hydroxy-2???,6???-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products

Developing a continuous flow-square wave voltammetry method for determination of atrazine in soil solutions using the hanging mercury drop electrode

Directory of Open Access Journals (Sweden)

Santos Luciana B. O. dos

2006-01-01

Full Text Available This work describes the development of a Continuous Flow-Square Wave Voltammetry method for determination of atrazine using the hanging mercury drop electrode. The best signal to noise ratio was obtained at the square wave frequency of 350 Hz and flow rate of 0.47 mL min-1. Under these conditions, the analytical curve obtained in 0.010 mol L-1 CaCl2 soil extracts in presence of 40 mmol L-1 BR buffer and 0.25 mol L-1 NaNO3 was linear for atrazine concentrations between 0.10 and 2.0 µg mL-1, with detection and quantification limits of 0.030 and 0.10 µg mL-1, respectively. The proposed method increased the analytical throughput in comparison with the batch methodology, allowing a sampling frequency of 72 h-1 to be accomplished. Besides, the sample consumption is significantly reduced, and only 341 µL are necessary for each analysis. The results obtained were similar to the ones obtained by HPLC, but the proposed method is faster and does not use organic solvents.

Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments.

Science.gov (United States)

Boily, Monique; Sarrasin, Benoit; Deblois, Christian; Aras, Philippe; Chagnon, Madeleine

2013-08-01

In Québec, as observed globally, abnormally high honey bee mortality rates have been reported recently. Several potential contributing factors have been identified, and exposure to pesticides is of increasing concern. In maize fields, foraging bees are exposed to residual concentrations of insecticides such as neonicotinoids used for seed coating. Highly toxic to bees, neonicotinoids are also reported to increase AChE activity in other invertebrates exposed to sub-lethal doses. The purpose of this study was therefore to test if the honey bee's AChE activity could be altered by neonicotinoid compounds and to explore possible effects of other common products used in maize fields: atrazine and glyphosate. One week prior to pollen shedding, beehives were placed near three different field types: certified organically grown maize, conventionally grown maize or non-cultivated. At the same time, caged bees were exposed to increasing sub-lethal doses of neonicotinoid insecticides (imidacloprid and clothianidin) and herbicides (atrazine and glyphosate) under controlled conditions. While increased AChE activity was found in all fields after 2 weeks of exposure, bees close to conventional maize crops showed values higher than those in both organic maize fields and non-cultivated areas. In caged bees, AChE activity increased in response to neonicotinoids, and a slight decrease was observed by glyphosate. These results are discussed with regard to AChE activity as a potential biomarker of exposure for neonicotinoids.

Radiation degradation of silk

Energy Technology Data Exchange (ETDEWEB)

Ishida, Kazushige; Kamiishi, Youichi [Textile Research Institute of Gunma, Kiryu, Gunma (Japan); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2001-03-01

Silk fibroin powder was prepared from irradiated silk fibroin fiber by means of only physical treatment. Silk fibroin fiber irradiated with an accelerated electron beam in the dose range of 250 - 1000 kGy was pulverized by using a ball mill. Unirradiated silk fibroin fiber was not pulverized at all. But the more irradiation was increased, the more the conversion efficiency from fiber to powder was increased. The conversion efficiency of silk fibroin fiber irradiated 1000 kGy in oxygen was 94%. Silk fibroin powder shows remarkable solubility, which dissolved 57% into water of ambient temperature. It is a very interesting phenomenon that silk fibroin which did not treat with chemicals gets solubility only being pulverized. In order to study mechanism of solubilization of silk fibroin powder, amino acid component of soluble part of silk fibroin powder was analyzed. The more irradiation dose up, the more glycine or alanine degraded, but degradation fraction reached bounds about 50%. Other amino acids were degraded only 20% even at the maximum. To consider crystal construction of silk fibroin, it is suggested that irradiation on silk fibroin fiber selectively degrades glycine and alanine in amorphous region, which makes it possible to pulverize and to dissolve silk fibroin powder. (author)

Sequential Isolation of Saturated, Aromatic, Resinic and Asphaltic Fractions Degrading Bacteria from Oil Contaminated Soil in South Sumatera

Directory of Open Access Journals (Sweden)

Pingkan Aditiawati

2012-04-01

Full Text Available Sequential isolation has been conducted to obtain isolates of saturated, aromatic, resin, and asphaltene fractions degrading bacteria from oil contaminated sites. Five soil samples were collected from South Sumatera. These were analyzed using soil extract medium enriched with oil recovery or Remaining-Oil recovery Degradated (ROD as sole carbon and energy sources according to the isolation stage. ROD at the end of every isolation stage analyzed oil fractions by use of the SARA analysis method. Six isolates of bacteria have been selected, one isolate was fraction saturates degrading bacteria that are Mycobacterium sp. T1H2D4-7 at degradation rate 0.0199 mgs/h with density 8.4x106 cfu/g from stage I. The isolate T2H1D2-4, identified as Pseudomonas sp. was fraction aromatics degrading bacteria at accelerate 0.0141 mgs/h with density 5.1x106 cfu/g are obtained at stage II. Two isolates namely Micrococcus sp. T3H2D4-2 and Pseudomonas sp. T1H1D5-5 were fraction resins degrading bacteria by accelerate 0.0088 mgs/h at density 5.6x106 cfu/g and 0.0089 mgs/h at density 5.7x106 cfu/g are obtained at stage III. Isolation of stage IV has been obtained two isolates Pseudomonas sp. T4H1D3-1and Pseudomonas sp. T4H3D5-4 were fraction asphaltenes degrading bacteria by accelerate 0.0057 mgs/h at density 5.6x106 cfu/g and accelerate 0.0058 mgs/h at density 5.7x106 cfu/g.

Effect of Graphite Doped TiO_2 Nanoparticles on Smoke Degradation

International Nuclear Information System (INIS)

Roshasnorlyza Hazan; Mohamad Shahrizal Md Zain; Natrah Syafiqah Rosli

2016-01-01

Secondhand smoke affects in the same way as regular smoker. The best solution is to purify the air efficiently and effectively. In this study, we were successfully doped TiO_2 nanoparticle with graphite to accelerate the degradation of cigarette smoke. The graphite doped and undoped TiO_2 nanoparticles were prepared from synthetic rutile using alkaline fusion method and their photo catalytic activity were investigated under visible light irradiation. The photo catalytic activity of the TiO_2 nanoparticles was analyzed in terms of their particle size analysis, crystallization and optical band gap. TiO_2 nanoparticle act as photo catalyzer by utilization of light energy to excite electron-hole pairs in smoke degradation processes. With the aided from graphite in TiO_2 nanoparticles, the smoke degradation was accelerate up to 44.4 %. In this case, graphite helps to reduce optical band gap of TiO_2 nanoparticle, thus increasing excitation of electron from valence band to conduction band. (author)

Degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid nanocomposite in simulated body fluid

International Nuclear Information System (INIS)

Liuyun, Jiang; Chengdong, Xiong; Lixin, Jiang; Lijuan, Xu

2013-01-01

Graphical abstract: In this manuscript, we initiated a systematic study to investigate the effect of HA on thermal properties, inner structure, reduction of mechanical strength, surface morphology and the surface deposit of n-HA/PLGA composite with respect to the soaking time. The results showed that n-HA played an important role in improving the degradation behavior of n-HA/PLGA composite, which can accelerate the degradation of n-HA/PLGA composite and endow it with bioactivity, after n-HA was detached from PLGA during the degradation, so that n-HA/PLGA composite may have a more promising prospect of the clinical application than pure PLGA as bone fracture internal fixation materials, and the results would be of reference significance to predict the in vivo degradation and biological properties. - Highlights: • Effect of n-HA on degradation behavior of n-HA/PLGA composite was investigated. • Degradation behaviors of n-HA/PLGA and PLGA were carried out in SBF for 6 months. • Viscosity, thermal properties, inner structure and bending strength were tested. • n-HA can accelerate the degradation and endows it with bioactivity. - Abstract: To investigate the effect of hydroxyapatite(HA) on the degradation behavior of hydroxyapatite/poly(lactic-co-glycolic) acid (HA/PLGA) nanocomposite, the degradation experiment of n-HA/PLGA composite and pure PLGA were carried out by soaking in simulated body fluid(SBF) at 37 °C for 1, 2, 4 and 6 months. The change of intrinsic viscosity, thermal properties, inner structure, bending strength reduction, surface morphology and the surface deposit of n-HA/PLGA composite and pure PLGA with respect to the soaking time were investigated by means of UbbeloHde Viscometer, differential scanning calorimeter (DSC), scanning electron microscope(SEM), electromechanical universal tester, a conventional camera and X-ray diffraction (XRD). The results showed that n-HA played an important role in improving the degradation behavior of n

Investigations on the Chemical Degradation of Silver Gelatine Prints

OpenAIRE

Maha Ahmed ALI; Mona Fouad ALI; Mohammed Osama SAKER; Abdel Azez El Bayoumi ABDEL ALEEM; Khaled Ibrahim EL NAGAR

2012-01-01

Photographs are considered composite objects with complex chemical and physical structures. Therefore they are more prone to damage as compared to other objects. Chemical degradation is by far the most common decay form found among photographic collections. This study investigates the chemical degradation of silver gelatin prints (DOP) and the reaction of the image, silver, gelatin, and paper to accelerated aging, to the action of light, and oxidizing gases, in terms of their physical and che...

Comparative study of active plasma lenses in high-quality electron accelerator transport lines

Science.gov (United States)

van Tilborg, J.; Barber, S. K.; Benedetti, C.; Schroeder, C. B.; Isono, F.; Tsai, H.-E.; Geddes, C. G. R.; Leemans, W. P.

2018-05-01

Electrically discharged active plasma lenses (APLs) are actively pursued in compact high-brightness plasma-based accelerators due to their high-gradient, tunable, and radially symmetric focusing properties. In this manuscript, the APL is experimentally compared with a conventional quadrupole triplet, highlighting the favorable reduction in the energy dependence (chromaticity) in the transport line. Through transport simulations, it is explored how the non-uniform radial discharge current distribution leads to beam-integrated emittance degradation and a charge density reduction at focus. However, positioning an aperture at the APL entrance will significantly reduce emittance degradation without additional loss of charge in the high-quality core of the beam. An analytical model is presented that estimates the emittance degradation from a short beam driving a longitudinally varying wakefield in the APL. Optimizing laser plasma accelerator operation is discussed where emittance degradation from the non-uniform discharge current (favoring small beams inside the APL) and wakefield effects (favoring larger beam sizes) is minimized.

Bidirectional impact of atrazine-induced elvations in progesterone (P4) on the LH Surge in the ovariectomized (OVX), estradiol (E2)-primed rat

Science.gov (United States)

Multiple daily exposures to the herbicide atrazine (ATZ) have been reported to suppress the luteinizing hormone surge (LHS) in female rats. Exposure has also been found to elevate P4 concentrations, and an increase in P4 is known to have a different directional effect on LH depen...

Occurrence of cyanazine compounds in groundwater: Degradates more prevalent than the parent compound

Science.gov (United States)

Kolpin, D.W.; Thurman, E.M.; Linhart, S.M.

2001-01-01

A recently developed analytical method using liquid chromatography/mass spectrometry was used to investigate the occurrence of cyanazine and its degradates cyanazine acid (CAC), cyanazine amide (CAM), deethylcyanazine (DEC), and deethylcyanazine acid (DCAC) in groundwater. This research represents some of the earliest data on the occurrence of cyanazine degradates in groundwater. Although cyanazine was infrequently detected in the 64 wells across Iowa sampled in 1999, cyanazine degradates were commonly found during this study. The most frequently detected cyanazine compound was DCAC (32.8%) followed by CAC (29.7%), CAM (17.2%), DEC (3.1%), and cyanazine (3.1%). The frequency of detection for cyanazine or one or more of its degradates (CYTOT) was more than 12-fold over that of cyanazine alone (39.1% for CYTOT versus 3.1% for cyanazine). Of the total measured concentration of cyanazine, only 0.2% was derived from its parent compound - with DCAC (74.1%) and CAC (18.4%) comprising 92.5% of this total. Thus, although DCAC and CAC had similar frequencies of detection, DCAC was generally present in higher concentrations. No concentrations of cyanazine compounds for this study exceeded water-quality criteria for the protection of human health. Only cyanazine, however, has such a criteria established. Nevertheless, because these cyanazine degradates are still chlorinated, they may have similar toxicity as their parent compound - similar to what has been found with the chlorinated degradates of atrazine. Thus, the results of this study documented that data on the degradates for cyanazine are critical for understanding its fate and transport in the hydrologic system. Furthermore, the prevalence of the chlorinated degradates of cyanazine found in groundwater suggests that to accurately determine the overall effect on human health and the environment from cyanazine its degradates should also be considered. In addition, because CYTOT was found in 57.6% of the samples collected

Determination of LEDs degradation with entropy generation rate

Science.gov (United States)

Cuadras, Angel; Yao, Jiaqiang; Quilez, Marcos

2017-10-01

We propose a method to assess the degradation and aging of light emitting diodes (LEDs) based on irreversible entropy generation rate. We degraded several LEDs and monitored their entropy generation rate ( S ˙ ) in accelerated tests. We compared the thermoelectrical results with the optical light emission evolution during degradation. We find a good relationship between aging and S ˙ (t), because S ˙ is both related to device parameters and optical performance. We propose a threshold of S ˙ (t) as a reliable damage indicator of LED end-of-life that can avoid the need to perform optical measurements to assess optical aging. The method lays beyond the typical statistical laws for lifetime prediction provided by manufacturers. We tested different LED colors and electrical stresses to validate the electrical LED model and we analyzed the degradation mechanisms of the devices.

Characteristic Experimentations of Degrader and Scatterer at MC-50 Cyclotron

CERN Document Server

Lee Seok Ki; Kim, Kye-Ryung; Lee, Hwa-Ryun; Park, Bum-Sik

2005-01-01

Building proton beam user facilities, especially deciding beam energy level, depends on the attached proton accelerator and users' needs. To adjust beam energy level, two methods are generally used. One is to directly adjust the beam in the accelerator. The other is to adjust beam energy after extracting from the accelerator. Degrader/Scatterer System has been installed in the MC-50 Cyclotron to adjust energy level of the beam used for various application fields. Its degrader and scatterer are made of Al foils and Au foils, respectively. Al thickness are 2, 1, 0.5, 0.3, 0.2, 0.1, 0.05, 0.03, 0.02, 0.01mm and Au thickness are 0.2, 0.1, 0.05, 0.03, 0.02, 0.01mm, respectively. In this study, suitable beam condition was adjusted through overlapping Al/Au foils of various thickness through simulation results. After that, LET(Linear Energy Transfer) value was indirectly acquired by measuring the bragg peak of the external beam through PMMA plastic Phantom and profile was measured by film dosimetry.

Accelerated remediation of pesticide-contaminated soil with zerovalent iron

Energy Technology Data Exchange (ETDEWEB)

Shea, P.J. [University of Nebraska-Lincoln, Lincoln, NE 68583-0915 (United States)]. E-mail: pshea@unl.edu; Machacek, T.A. [University of Nebraska-Lincoln, Lincoln, NE 68583-0915 (United States); Comfort, S.D. [University of Nebraska-Lincoln, Lincoln, NE 68583-0915 (United States)

2004-11-01

High pesticide concentrations in soil from spills or discharges can result in point-source contamination of ground and surface waters. Cost-effective technologies are needed for on-site treatment that meet clean-up goals and restore soil function. Remediation is particularly challenging when a mixture of pesticides is present. Zerovalent iron (Fe{sup 0}) has been shown to promote reductive dechlorination and nitro group reduction of a wide range of contaminants in soil and water. We employed Fe{sup 0} for on-site treatment of soil containing >1000 mg metolachlor, >55 mg alachlor, >64 mg atrazine, >35 mg pendimethalin, and >10 mg chlorpyrifos kg{sup -1}. While concentrations were highly variable within the windrowed soil, treatment with 5% (w/w) Fe{sup 0} resulted in >60% destruction of the five pesticides within 90 d and increased to >90% when 2% (w/w) Al{sub 2}(SO{sub 4}){sub 3} was added to the Fe{sup 0}. GC/MS analysis confirmed dechlorination of metolachlor and alachlor during treatment. Our observations support the use of Fe{sup 0} for ex situ treatment of pesticide-contaminated soil. - Capsule: Zerovalent iron promotes pesticide degradation in highly contaminated soil.

Accelerated Stress-Corrosion Testing

Science.gov (United States)

1986-01-01

Test procedures for accelerated stress-corrosion testing of high-strength aluminum alloys faster and provide more quantitative information than traditional pass/fail tests. Method uses data from tests on specimen sets exposed to corrosive environment at several levels of applied static tensile stress for selected exposure times then subsequently tensile tested to failure. Method potentially applicable to other degrading phenomena (such as fatigue, corrosion fatigue, fretting, wear, and creep) that promote development and growth of cracklike flaws within material.

THE EFFECT OF ATRAZINE ON PUBERTY IN THE MALE WISTAR RATS: AN EVALUATION IN THE PROTOCOL FOR THE ASSESSMENT OF PUBERTAL DEVELOPMENT AND THYROID FUNCTION

Science.gov (United States)

Since atrazine (ATR), a chlorotriazine herbicide, has been shown previously to alter the secretion of luteinizing hormone (LH) and prolactin (PRL) through a direct effect on the central nervous system (CNS), we hypothesized that exposure to ATR in the EDSTAC male pubertal protoco...

Accelerating the life of transistors

International Nuclear Information System (INIS)

Qi Haochun; Lü Changzhi; Zhang Xiaoling; Xie Xuesong

2013-01-01

Choosing small and medium power switching transistors of the NPN type in a 3DK set as the study object, the test of accelerating life is conducted in constant temperature and humidity, and then the data are statistically analyzed with software developed by ourselves. According to degradations of such sensitive parameters as the reverse leakage current of transistors, the lifetime order of transistors is about more than 10 4 at 100 °C and 100% relative humidity (RH) conditions. By corrosion fracture of transistor outer leads and other failure modes, with the failure truncated testing, the average lifetime rank of transistors in different distributions is extrapolated about 10 3 . Failure mechanism analyses of degradation of electrical parameters, outer lead fracture and other reasons that affect transistor lifetime are conducted. The findings show that the impact of external stress of outer leads on transistor reliability is more serious than that of parameter degradation. (semiconductor devices)

Managed aquifer recharge as environmental tool risk mitigation linked to the presence of herbicides.

Science.gov (United States)

Di Roma, Antonella; Nieto Yàbar, Daniel; Pepi, Salvatore; Vaccaro, Carmela

2017-04-01

The pollution due to some herbicides which was used in flood plains and karst areas of various regions in the world is causing major problems in supplying drinking water from surface water bodies and aquifers. Pesticides and herbicides are widely used in agriculture, vineyards, industry and public hygiene. They are spread on soil surface, in air, into deep soil causing problems in surface water bodies and aquifers. In Italy the interest of presence of pesticides in water resources began around 1980 after episodes of drinking water contamination due to some herbicides and atrazine (ATR). After years away from the ban on the use of atrazine (use prohibition in the 90's), its degradation products are still present in groundwater of large areas of the plains of Nord Italy (Bottoni et al.,2013). Intensive use of triazines has become harmful for the local population that live in the Veneto-Friuli plain where the high gravels permeability of alluvial fans allowed to the widespread diffusion of triazines and related metabolites. The main mechanism of atrazine action in soil is microbial degradation, the kinetics of these products is closely connected with the availability of nitrates in the soil. The half-life of atrazine is 30-180 days but its disintegration is blocked by nitrates presence (Jones et al 1982). ATR is trapped in cohesive levels as peat and silty clay soils and periodically released by the interaction water sediment. Artificial recharge in areas with highly permeable aquifers allows to realize qualitative and quantitative regeneration because water low in nitrates and Dissolved Oxygen can promote the biological and chemical disintegration of pesticides such as atrazine and its metabolites. A case study is represented by the Friuli plain, near the Tagliamento river. Based on the WARBO project data that has applied artificial recharge in Mereto di Tomba test site where the dissolved nitrate content of water in some cases exceed the 50 mg/L limit according to

Fast detection of atrazine in corn using thermometric biosensors.

Science.gov (United States)

Qie, Zhiwei; Ning, Baoan; Liu, Ming; Bai, Jialei; Peng, Yuan; Song, Nan; Lv, Zhiqiang; Wang, Ying; Sun, Siming; Su, Xuan; Zhang, Yihong; Gao, Zhixian

2013-09-07

Fast detection is important in screening large-scale samples. This study establishes a direct competitive ELISA method (dcTELISA) based on an enzyme thermistor for fast atrazine (ATZ) detection. ATZ competes with β-lactamase-labeled ATZ (ATZ-E) for the binding sites on anti-ATZ monoclonal antibody (mAb). The mAb are covalently bound to Controlled Pore Glass (CPG) in an immunoreactor to form immunocomplexes with ATZ and ATZ-E. Several parameters of biosensor performance were optimized, such as the ATZ-E concentration, concentration and nature of the substrate, flow rate, and effect of temperature on the sensor response. After optimization, the assay time for a single sample was 12 min. The work process and result were compared with those of high-performance liquid chromatography (HPLC). The detection results exhibited a recovery rate of 88% to 107% in ATZ-spiked fresh cut corn stalks and silage samples. The results obtained via dcTELISA had good correlation with that of HPLC, and the biosensor response was reproducible and stable even when used continuously for over 4 months. All these properties suggested that the fast detection method, dcTELISA, may be used to detect pesticide residue in large-scale samples.

[6]-Shogaol Inhibits α-MSH-Induced Melanogenesis through the Acceleration of ERK and PI3K/Akt-Mediated MITF Degradation

Directory of Open Access Journals (Sweden)

Huey-Chun Huang

2014-01-01

Full Text Available [6]-Shogaol is the main biologically active component of ginger. Previous reports showed that [6]-shogaol has several pharmacological characteristics, such as antioxidative, anti-inflammatory, antimicrobial, and anticarcinogenic properties. However, the effects of [6]-shogaol on melanogenesis remain to be elucidated. The study aimed to evaluate the potential skin whitening mechanisms of [6]-shogaol. The effects of [6]-shogaol on cell viability, melanin content, tyrosinase activity, and the expression of the tyrosinase and microphthalmia-associated transcription factor (MITF were measured. The results revealed that [6]-shogaol effectively suppresses tyrosinase activity and the amount of melanin and that those effects are more pronounced than those of arbutin. It was also found that [6]-shogaol decreased the protein expression levels of tyrosinase-related protein 1 (TRP-1 and microphthalmia-associated transcriptional factor (MITF. In addition, the MITF mRNA levels were also effectively decreased in the presence of 20 μM [6]-shogaol. The degradation of MITF protein was inhibited by the MEK 1-inhibitor (U0126 or phosphatidylinositol-3-kinase inhibitor (PI3K inhibitor (LY294002. Further immunofluorescence staining assay implied the involvement of the proteasome in the downregulation of MITF by [6]-shogaol. Our confocal assay results also confirmed that [6]-shogaol inhibited α-melanocyte stimulating hormone- (α-MSH- induced melanogenesis through the acceleration of extracellular responsive kinase (ERK and phosphatidylinositol-3-kinase- (PI3K/Akt- mediated MITF degradation.

Microcantilever sensors for fast analysis of enzymatic degradation of poly (D, L-lactide)

DEFF Research Database (Denmark)

Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

2015-01-01

of the biodegradation rate of PDLLA with a minute amount of sample and without the need of thermal and chemical acceleration. The degradation rate of the polymer has been estimated by multilayer cantilever theory and model simulation. A bulk degradation rate of 0.24 μg mm-2 hour-1 is estimated which agrees well...

Influence of the formation- and passivation rate of boron-oxygen defects for mitigating carrier-induced degradation in silicon within a hydrogen-based model

International Nuclear Information System (INIS)

Hallam, Brett; Abbott, Malcolm; Nampalli, Nitin; Hamer, Phill; Wenham, Stuart

2016-01-01

A three-state model is used to explore the influence of defect formation- and passivation rates of carrier-induced degradation related to boron-oxygen complexes in boron-doped p-type silicon solar cells within a hydrogen-based model. The model highlights that the inability to effectively mitigate carrier-induced degradation at elevated temperatures in previous studies is due to the limited availability of defects for hydrogen passivation, rather than being limited by the defect passivation rate. An acceleration of the defect formation rate is also observed to increase both the effectiveness and speed of carrier-induced degradation mitigation, whereas increases in the passivation rate do not lead to a substantial acceleration of the hydrogen passivation process. For high-throughput mitigation of such carrier-induced degradation on finished solar cell devices, two key factors were found to be required, high-injection conditions (such as by using high intensity illumination) to enable an acceleration of defect formation whilst simultaneously enabling a rapid passivation of the formed defects, and a high temperature to accelerate both defect formation and defect passivation whilst still ensuring an effective mitigation of carrier-induced degradation

Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

International Nuclear Information System (INIS)

Leech, Dina M.; Snyder, Matthew T.; Wetzel, Robert G.

2009-01-01

Nanomolar concentrations of steroid hormones such as 17β-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17β-estradiol demonstrated modest photodegradation (∼ 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased (∼ 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone

Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

Energy Technology Data Exchange (ETDEWEB)

Leech, Dina M. [Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557 (United States)], E-mail: dmleech@email.unc.edu; Snyder, Matthew T.; Wetzel, Robert G. [Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States)

2009-03-01

Nanomolar concentrations of steroid hormones such as 17{beta}-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17{beta}-estradiol demonstrated modest photodegradation ({approx} 26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased ({approx} 40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone.

Comparative study of modified polypropylene nanocomposites under environment and accelerated ageing conditions

International Nuclear Information System (INIS)

Komatsu, Luiz Gustavo Hiroki

2016-01-01

The understanding of degradation mechanism action on the polymer nanocomposites in face of weathering (UV light, heat, acid rain, among others), is the key for development of new additives and new applications. In this work the nanocomposite synthesis was carried in molten state, using twin-screw extruder. The polymer matrix was the HMS-PP (high melt polypropylene) synthesized by gamma irradiation and the nanometric inorganic component was the montmorillonite clay. For better compatibilization between the matrix and clay, it were used maleic anhydride as coupling agent. For environment and in oven accelerated aging assays, the dumbbell samples were prepared under hot pressing. The characterization of clay addition effects and aging effects on the nanocomposites, required the use of techniques of Differential Scanning Calorimetry (DSC), Thermogravimetry (TGA), Fourier Transformed Infrared Spectroscopy (FT-IR), Xray Fluorescence (WDXRF), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and mechanical properties. Samples with 0.1; 1; 3; 5; 10 % of clay were tested. The sample with 5% of clay showed better stability on the environmental assay and accelerated aging in oven assay. On the other hand, the sample with higher percent of clay (10%), was more degraded under on environmental aging than under accelerated aging in stove. In this case, became more resistant until 56 days of assay. On the studied concentrations (less than ≤ 3%) of clay, it can be seen an equilibrium between barrier effect and metallic ions action accelerating the degradative process. (author)

Bio stimulation for the Enhanced Degradation of Herbicides in Soil

International Nuclear Information System (INIS)

Kanissery, R.G; Sims, G.K

2011-01-01

Cleanup of herbicide-contaminated soils has been a dire environmental concern since the advent of industrial era. Although microorganisms are excellent degraders of herbicide compounds in the soil, some reparation may need to be brought about, in order to stimulate them to degrade the herbicide at a faster rate in a confined time frame. Bio stimulation through the appropriate utilization of organic amendments and nutrients can accelerate the degradation of herbicides in the soil. However, effective use of bio stimulants requires thorough comprehension of the global redox cycle during the microbial degradation of the herbicide molecules in the soil. In this paper, we present the prospects of using bio stimulation as a powerful remediation strategy for the rapid cleanup of herbicide-polluted soils.

Toxicity estimates for diuron and atrazine for the tropical marine cnidarian Exaiptasia pallida and in-hospite Symbiodinium spp. using PAM chlorophyll-a fluorometry.

Science.gov (United States)

Howe, Pelli Louise; Reichelt-Brushett, Amanda Jean; Clark, Malcolm William; Seery, Cliff Ross

2017-06-01

Effective ecotoxicological risk assessments for herbicides in tropical marine environments are restricted by a lack of toxicity data, sensitive test methods and endpoints for relevant species, and this requires rectification. The symbiotic sea anemone Exaiptasia pallida is a suitable test species, representing the phylum Cnidaria and allowing for assessments of toxicological responses of both the animal host and in-hospite Symbiodinium spp. Pulse amplitude modulated (PAM) chlorophyll-a fluorometry is recognised as a valuable ecotoxicological tool, and here newly-developed test methods are presented using PAM fluorometry to measure herbicide effects on photosynthetic efficiency of in-hospite Symbiodinium spp. Additionally, measurements on healthy laboratory-reared E. pallida provide baseline data demonstrating the normal effective quantum yield (EQY) and the maximum electron transport rate (ETR m ) for Symbiodinium spp. in the absence of herbicide stress. Concentration-dependant reductions in the EQY and ETR m occurred during diuron and atrazine exposures; a mean 48-h EC50 (effective concentration; 50%) of 8μg/L of diuron was estimated, however atrazine elicited a much lower toxicity. Twelve-day exposures to 10-200μg/L diuron showed that the greatest EQY effect occurred during the first 48h, with little subsequent change. However, longer exposures to the lowest diuron treatment (1μg/L) showed the lowest EQYs after 96h followed by recovery to control levels within 12d. Furthermore, asexual reproduction was inhibited during 12-d exposures to diuron, and 12-d EC50 values of 100 and 132μg/L were estimated to inhibit successful reproduction of pedal lacerates and juveniles by 50% respectively. This study provides much needed data contributions to species sensitivity curves for development of diuron and atrazine water quality guidelines in tropical marine environments. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct ubiquitin independent recognition and degradation of a folded protein by the eukaryotic proteasomes-origin of intrinsic degradation signals.

Directory of Open Access Journals (Sweden)

Amit Kumar Singh Gautam

Full Text Available Eukaryotic 26S proteasomes are structurally organized to recognize, unfold and degrade globular proteins. However, all existing model substrates of the 26S proteasome in addition to ubiquitin or adaptor proteins require unstructured regions in the form of fusion tags for efficient degradation. We report for the first time that purified 26S proteasome can directly recognize and degrade apomyoglobin, a globular protein, in the absence of ubiquitin, extrinsic degradation tags or adaptor proteins. Despite a high affinity interaction, absence of a ligand and presence of only helices/loops that follow the degradation signal, apomyoglobin is degraded slowly by the proteasome. A short floppy F-helix exposed upon ligand removal and in conformational equilibrium with a disordered structure is mandatory for recognition and initiation of degradation. Holomyoglobin, in which the helix is buried, is neither recognized nor degraded. Exposure of the floppy F-helix seems to sensitize the proteasome and primes the substrate for degradation. Using peptide panning and competition experiments we speculate that initial encounters through the floppy helix and additional strong interactions with N-terminal helices anchors apomyoglobin to the proteasome. Stabilizing helical structure in the floppy F-helix slows down degradation. Destabilization of adjacent helices accelerates degradation. Unfolding seems to follow the mechanism of helix unraveling rather than global unfolding. Our findings while confirming the requirement for unstructured regions in degradation offers the following new insights: a origin and identification of an intrinsic degradation signal in the substrate, b identification of sequences in the native substrate that are likely to be responsible for direct interactions with the proteasome, and c identification of critical rate limiting steps like exposure of the intrinsic degron and destabilization of an unfolding intermediate that are presumably

Radiation degradation of silk protein

Energy Technology Data Exchange (ETDEWEB)

Wachiraporn Pewlong; Boonya Sudatis [Office of Atomic Energy for Peace, Bangkok (Thailand); Takeshita, Hidefumi; Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2000-09-01

Silk fibroin fiber from the domesticated silkworm Bombyx mori was irradiated in the dose range up to 2500 kGy using an electron beam accelerator to apply the radiation degradation technique as a means to solubilize fibroin. The tensile strength of irradiated fibroin fiber decreased with increasing dose and the presence of oxygen in the irradiation atmosphere enhanced the degradation. The solubilization of irradiated fibroin fiber was evaluated using the following three kinds of solutions: calcium chloride solution (CaCl{sub 2}/C{sub 2}H{sub 5}OH/H{sub 2}O = 1 : 2 : 8 in mole ratio), hydrochloric acid (0.5N) and distilled water. Dissolution of fibroin fiber into these solutions was significantly enhanced by irradiation. Especially, an appreciable amount of water-soluble protein was extracted by distilled water. (author)

Improved Accelerated Stress Tests Based on Fuel Cell Vehicle Data

Energy Technology Data Exchange (ETDEWEB)

Patterson, Timothy [Research Engineer; Motupally, Sathya [Research Engineer

2012-06-01

UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells. This in-depth investigation will focused on critical fuel cell components (e.g. membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. UTC had access to MEA materials that had accrued significant load time under real-world conditions in PureMotion® 120 power plant used in transit buses. These materials are referred to as end-of-life (EOL) components in the rest of this document. Advanced characterization techniques were used to evaluate degradation mode progress using these critical cell components extracted from both bus power plants and corresponding materials tested using the DOE AST’s. These techniques were applied to samples at beginning-of-life (BOL) to serve as a baseline. These comparisons advised the progress of the various failure modes that these critical components were subjected to, such as membrane degradation, catalyst support corrosion, platinum group metal dissolution, and others. Gaps in the existing ASTs predicted the degradation observed in the field in terms of these modes were outlined. Using the gaps, new AST’s were recommended and tested to better reflect the degradation modes seen in field operation. Also, BOL components were degraded in a test vehicle at UTC designed to accelerate the bus field operation.

Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

DEFF Research Database (Denmark)

Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

2013-01-01

Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... of the polymer. Fuel cell durability tests with contaminations of ferrous ions did show considerable performance degradation, however, primarily due to the catalyst deterioration rather than the membrane degradation........ In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer...

Photocatalytic Degradation of Malachite Green Using Nano-sized cerium-iron Oxide

Directory of Open Access Journals (Sweden)

K. L. Ameta

2014-05-01

Full Text Available Nano-sized cerium-iron oxide nanoparticles has been synthesized, characterized and explored as an efficient photocatalyst for the photocatalytic degradation of malachite green. The effects of different variables on degradation of dye were optimized such as the pH of the dye solution, dye concentration, amount of photocatalyst and light intensity. About 91% degradation of dye of 2×10-5 M concentration was observed after 2 hours at 8.5 pH and 600 Wm-2 light intensity. The reason for the high catalytic activity of the synthesized nanoparticles is ascribed to the high surface area which determines the active sites of the catalyst and accelerates the photocatalytic degradation.

Mixture toxicity of three photosystem II inhibitors (atrazine, isoproturon, and diuron) toward photosynthesis of freshwater phytoplankton studied in outdoor mesocosms.

Science.gov (United States)

Knauert, Stefanie; Escher, Beate; Singer, Heinz; Hollender, Juliane; Knauer, Katja

2008-09-01

Mixture toxicity of three herbicides with the same mode of action was studied in a long-term outdoor mesocosm study. Photosynthetic activity of phytoplankton as the direct target site of the herbicides was chosen as physiological response parameter. The three photosystem II (PSII) inhibitors atrazine, isoproturon, and diuron were applied as 30% hazardous concentrations (HC30), which we derived from species sensitivity distributions calculated on the basis of EC50 growth inhibition data. The respective herbicide mixture comprised 1/3 of the HC30 of each herbicide. Short-term laboratory experiments revealed that the HC30 values corresponded to EC40 values when regarding photosynthetic activity as the response parameter. In the outdoor mesocosm experiment, effects of atrazine, isoproturon, diuron and their mixture on the photosynthetic activity of phytoplankton were investigated during a five-week period with constant exposure and a subsequent five-month postexposure period when the herbicides dissipated. The results demonstrated that mixture effects determined at the beginning of constant exposure can be described by concentration addition since the mixture elicited a phytotoxic effect comparable to the single herbicides. Declining effects on photosynthetic activity during the experiment might be explained by both a decrease in water herbicide concentrations and by the induction of community tolerance.

Status of peatland degradation and development in Sumatra and Kalimantan.

Science.gov (United States)

Miettinen, Jukka; Liew, Soo Chin

2010-01-01

Peatlands cover around 13 Mha in Sumatra and Kalimantan, Indonesia. Human activities have rapidly increased in the peatland ecosystems during the last two decades, invariably degrading them and making them vulnerable to fires. This causes high carbon emissions that contribute to global climate change. For this article, we used 94 high resolution (10-20 m) satellite images to map the status of peatland degradation and development in Sumatra and Kalimantan using visual image interpretation. The results reveal that less than 4% of the peatland areas remain covered by pristine peatswamp forests (PSFs), while 37% are covered by PSFs with varying degree of degradation. Furthermore, over 20% is considered to be unmanaged degraded landscape, occupied by ferns, shrubs and secondary growth. This alarming extent of degradation makes peatlands vulnerable to accelerated peat decomposition and catastrophic fire episodes that will have global consequences. With on-going degradation and development the existence of the entire tropical peatland ecosystem in this region is in great danger.

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

International Nuclear Information System (INIS)

Gao Jinzhang; Ma Dongping; Guo Xiao; Wang Aixiang; Fu Yan; Wu Jianlin; Yang Wu

2008-01-01

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe 2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. mol -1 and the pre-exponential factor ko of 2.065x10 -1 min -1 were obtained, too. The determination of hydroxyl radical was carried out by using N,N-dimethyl-p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

Science.gov (United States)

Gao, Jinzhang; Ma, Dongping; Guo, Xiao; Wang, Aixiang; Fu, Yan; Wu, Jianlin; Yang, Wu

2008-08-01

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. mol-1 and the pre-exponential factor ko of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N,N-dimethyl-p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

Degradation of diuron in aqueous solution by dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Feng Jingwei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China); Zheng Zheng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)], E-mail: zzheng@nju.edu.cn; Sun Yabing; Luan Jingfei; Wang Zhen; Wang Lianhong; Feng Jianfang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment Nanjing University, Nanjing 210093 (China)

2008-06-15

Degradation of diuron in aqueous solution was conducted in a dielectric barrier discharge (DBD) reactor and the proposed degradation mechanism was investigated in detail. The factors that affect the degradation of diuron were examined. The degradation efficiency of diuron and the removal of total organic carbon (TOC) increased with increasing input power, and the degradation of diuron by DBD fitted first-order kinetics. Both strong acidic and alkaline solution conditions could improve diuron degradation efficiency and TOC removal rate. Degradation of diuron could be accelerated or inhibited in the presence of H{sub 2}O{sub 2} depending on the dosage. The degradation efficiency increased dramatically with adding Fe{sup 2+}. The removal of TOC and the amount of the detected Cl{sup -}, NO{sub 3}{sup -} and NH{sub 4}{sup +} were increased in the presence of Fe{sup 2+}. The concentrations of oxalic and acetic acids were almost the same in the absence and presence of Fe{sup 2+}, but high concentration of formic acid was accumulated in the presence of Fe{sup 2+}. The main degradation pathway of diuron by DBD involved a series of dechlorination-hydroxylation, dealkylation and oxidative opening of the aromatic ring processes.

Degradation of biodegradable plastic mulch films in soil environment by phylloplane fungi isolated from gramineous plants.

Science.gov (United States)

Koitabashi, Motoo; Noguchi, Masako T; Sameshima-Yamashita, Yuka; Hiradate, Syuntaro; Suzuki, Ken; Yoshida, Shigenobu; Watanabe, Takashi; Shinozaki, Yukiko; Tsushima, Seiya; Kitamoto, Hiroko K

2012-08-02

To improve the biodegradation of biodegradable plastic (BP) mulch films, 1227 fungal strains were isolated from plant surface (phylloplane) and evaluated for BP-degrading ability. Among them, B47-9 a strain isolated from the leaf surface of barley showed the strongest ability to degrade poly-(butylene succinate-co-butylene adipate) (PBSA) and poly-(butylene succinate) (PBS) films. The strain grew on the surface of soil-mounted BP films, produced breaks along the direction of hyphal growth indicated that it secreted a BP-degrading enzyme, and has directly contributing to accelerating the degradation of film. Treatment with the culture filtrate decomposed 91.2 wt%, 23.7 wt%, and 14.6 wt% of PBSA, PBS, and commercially available BP polymer blended mulch film, respectively, on unsterlized soil within 6 days. The PCR-DGGE analysis of the transition of soil microbial community during film degradation revealed that the process was accompanied with drastic changes in the population of soil fungi and Acantamoeba spp., as well as the growth of inoculated strain B47-9. It has a potential for application in the development of an effective method for accelerating degradation of used plastics under actual field conditions.

Degradation of tropoelastin and skin elastin by neprilysin

DEFF Research Database (Denmark)

Mora Huertas, Angela C.; Schmelzer, Christian E. H.; Luise, Chiara

2018-01-01

was to investigate the degradation of fibrillar skin elastin by neprilysin and the influence of the donor's age on the degradation process using mass spectrometry and bioinformatics approaches. The results showed that cleavage by neprilysin is dependent on previous damage of elastin. While neprilysin does not cleave...... young and intact skin elastin well, it degrades elastin fibers from older donors, which may further promote aging processes. With regards to the cleavage behavior of neprilysin, a strong preference for Gly at P1 was found, while Gly, Ala and Val were well accepted at P1' upon cleavage of tropoelastin...... and skin elastin. The results of the study indicate that the progressive release of bioactive elastin peptides by neprilysin upon skin aging may enhance local tissue damage and accelerate extracellular matrix aging processes....

Neuroprotective mechanism of Kai Xin San: upregulation of hippocampal insulin-degrading enzyme protein expression and acceleration of amyloid-beta degradation

Directory of Open Access Journals (Sweden)

Na Wang

2017-01-01

Full Text Available Kai Xin San is a Chinese herbal formula composed of Radix Ginseng , Poria , Radix Polygalae and Acorus Tatarinowii Rhizome . It has been used in China for many years for treating amnesia. Kai Xin San ameliorates amyloid-β (Aβ-induced cognitive dysfunction and is neuroprotective in vivo , but its precise mechanism remains unclear. Expression of insulin-degrading enzyme (IDE, which degrades Aβ, is strongly correlated with cognitive function. Here, we injected rats with exogenous Aβ42 (200 μM, 5 μL into the hippocampus and subsequently administered Kai Xin San (0.54 or 1.08 g/kg/d intragastrically for 21 consecutive days. Hematoxylin-eosin and Nissl staining revealed that Kai Xin San protected neurons against Aβ-induced damage. Furthermore, enzyme-linked immunosorbent assay, western blot and polymerase chain reaction results showed that Kai Xin San decreased Aβ42 protein levels and increased expression of IDE protein, but not mRNA, in the hippocampus. Our findings reveal that Kai Xin San facilitates hippocampal Aβ degradation and increases IDE expression, which leads, at least in part, to the alleviation of hippocampal neuron injury in rats.

Integral Study of Atrazine Behaviour in Field Lysimeters in Argentinean Humid Pampas Soils Estudio Integral del Comportamiento de Atrazina en Lisímetros de Campo en Suelos de la Pampa Húmeda Argentina

Directory of Open Access Journals (Sweden)

Susana Hang

2010-03-01

Full Text Available Atrazine behavior during crop maize (Zea mays L. production in soils of Argentine humid pampas was investigated. Lysimeters (3.3 x 3.3 x 1.4 m with a Typic Argiudoll (Pergamino and others with a Typic Hapludoll (Junín were monitored for drainage water content and atrazine concentrations in soil and water. Soil profiles were sampled in four depths in three dates, and water drainage pooled in four periods. Most of atrazine loss in drainage occurred within 30 d of atrazine application being 0.13% and 0.03% of the total atrazine applied for Pergamino and Junín, respectively. Under laboratory conditions half-life average in both profiles was 16 d. Atrazine extractable residues (AER in lysimeters showed differences in quantity and distribution between both profiles. Extractable residues were 25.7 (Pergamino and 69.4 g ha-1 (Junín. At the 30th day of application, AER represented 25% of total AER in Junín and 88% in Pergamino in the first 30 cm. Occurrence of preferential flow through the Bt horizon (Pergamino may explain differences detected. High proportion of AER in Junín profile suggests low atrazine affinity and should be followed through time in order to evaluate actual stability of these residues and if they constitute a potential risk for aquifers.Se estudió el comportamiento de atrazina durante el ciclo de un cultivo de maíz (Zea mays L. en suelos de la pampa húmeda Argentina. Se monitoreó el total de agua drenada y la concentración de atrazina en suelo y agua, mediante el uso de seis lisímetros (3.3 x 3.3 x 1.4 m tres de ellos llenados con un Argiudoll Típico (Pergamino y otros tres con un Hapludoll Típico (Junín. Se tomaron muestras de cuatro horizontes en cada perfil de suelo en tres fechas y el agua drenada se agrupó en cuatro períodos. La mayor parte de las pérdidas de atrazina en el drenaje ocurrieron dentro de los primeros 30 días desde la aplicación de atrazina. Los porcentajes recuperados respecto de la cantidad

Accelerated laboratory weathering of acrylic lens materials

Science.gov (United States)

Arndt, Thomas; Richter, Steffen; Kogler, René; Pasierb, Mike; Walby, Christopher

2015-09-01

Flat samples from various poly(methyl methacrylate) (PMMA) formulations were subjected to outdoor weathering in Arizona and Florida, EMMAQUA® accelerated outdoor weathering, and two accelerated laboratory weathering procedures at 3 Sun irradiance which, imitate dry (Arizona) and wet (Florida) conditions. The main mode of degradation is yellowing and not the generation of haze for any weathering procedure within the investigated radiant exposure. Higher UV absorber concentrations lead to smaller changes in optical properties and in the resulting relative concentrator photovoltaic (CPV) module efficiencies. Comparison of sample properties after various weathering procedures reveals that the influence of weathering factors other than radiant exposure depends on the sample as well.

A reproducible accelerated in vitro release testing method for PLGA microspheres.

Science.gov (United States)

Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J

2016-02-10

The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures). Copyright © 2015 Elsevier B.V. All rights reserved.