Kegg Pathway: Atrazine degradation

Sci Total Environ. 2008 Jul 11;
Poissant L, Beauvais C, Lafrance P, Deblois C

A survey on pesticides (73 compounds) in the Bay St. François wetland and its catchment (part of the wetlands of Lake St. Pierre area [St. Lawrence River, Québec]) was achieved in 2006. The metabolites as well as the active ingredients of pesticides (11 compounds) were detected in the wetland and its catchment. This wetland ecosystem was active in the degradation of agricultural pesticides (e.g., Atrazine). The measured pesticides were individually below the criteria for aquatic species in natural water, except chlorpyrifos. Overall, the pesticides lost from agricultural field towards the streams were <1% of the quantity applied. The environmental fates of the pesticides were found to vary according to the size of the watershed. Over large catchments, half-life times were important in terms of global loss from the agricultural lands to wetlands whereas over small catchments, soil organic carbon/water distribution coefficient (Koc) was an important term for pesticides losses to water system since half-life times were not limiting factors.

Ecotoxicol Environ Saf. 2008 Jun 30;
Basfar AA, Mohamed KA, Al-Abduly AJ, Al-Shahrani AA

degradation of Atrazine herbicide in humic substances (HS) aqueous solutions and distilled water solutions was investigated on a laboratory scale upon gamma-irradiation from a (60)Co source. In addition, the effect of ionizing radiation on the Atrazine residues removal efficiency was investigated in relation to degradation of by-products. gamma-Irradiation experiments were carried out for three targeted concentrations (i.e. 0.464, 2.318 and 4.636muM) with doses over the range 0.1-60kGy. The initial concentration of herbicide, scavengers and irradiation doses play a significant role in the degradation efficiency as shown by decay constants of Atrazine residues. gamma-Radiolysis showed that Atrazine exhibited high degradation percentages at low absorbed doses in HS aqueous solutions compared to distilled water solutions. Absorbed doses from 0.6 to 21kGy and from 6 to 72kGy at a dose rate of 14.52kGyh(-1) achieved 90% degradation for Atrazine with initial concentrations over the range 0.464-4.636muM in humic and distilled water solutions, respectively. The radiolytic degradation by-products and their mass balances were qualitatively determined with good confidence using gas chromatography/quadruple mass spectrometry (GC/MS) with electron impact ionization (EI(+)) mode.

Environ Sci Technol. 2008 Jun 1; 42(11): 4208-14
Svendsen C, Owen J, Kille P, Wren J, Jonker MJ, Headley BA, Morgan AJ, Blaxter M, Stürzenbaum SR, Hankard PK, Lister LJ, Spurgeon DJ

Transcriptional responses of a soil-dwelling organism (the earthworm Lumbricus rubellus) to three chemicals, cadmium (Cd), fluoranthene (FA), and Atrazine (AZ), were measured following chronic exposure, with the aim of identifying the nature of any shared transcriptional response. Principal component analysis indicated full or partial separation of control and exposed samples for each compound but not for the composite set of all control and exposed samples. Partial least-squares discriminant analysis allowed separation of the control and exposed samples for each chemical and also for the composite data set, suggesting a common transcriptional response to exposure. Genes identified as changing in expression level (by the least stringent test for significance) following exposure to two chemicals indicated a substantial number of common genes (> 127). The three compound overlapping gene set, however, comprised only 25 genes. We suggest that the low commonality in transcriptional response may be linked to the chronic concentrations (approximately 10% EC50) and chronic duration (28 days) used. Annotations of the three compound overlapping gene set indicated that genes from pathways most often associated with responses to environmental stress, such as heat shock, phase I and II metabolism, antioxidant defense, and cation balance, were not represented. The strongest annotation signature was for genes important in mitochondrial function and energy metabolism.

J Environ Qual. 2008 Jul-Aug; 37(4): 1599-607
Kazemi HV, Anderson SH, Goyne KW, Gantzer CJ

Increased attention to ground water contamination has encouraged an interest in mechanisms of solute transport through soils. Few studies have investigated the effect of the initial soil water content on the transport and degradation of herbicides for claypan soils. We investigated the effect of claypan soils at initial field capacity vs. permanent wilting level on Atrazine and alachlor transport. The soil studied was Mexico silt loam (fine, smectitic, mesic Aeric Vertic Epiaqualf) with a subsoil clay content, primarily montmorillonite, of >40%. Strontium bromide, Atrazine, and alachlor were applied to plots; half were at field capacity (Wet treatment), and half were near the permanent wilting point (Dry treatment). Soil cores were removed at selected depths and times, and cores were analyzed for bromide and herbicide concentrations. Bromide, Atrazine, and alachlor were detected at the 0.90-m depth in dry plots within 15 d after experiment initiation. Bromide was detected 0.15 m deeper (P < 0.05) in the Dry compared with the Wet treatment at 1, 7, and 60 d after application and >0.30 m deeper (P < 0.01) in the Dry treatment at 15 and 30 d after application; similar treatment results were found for Atrazine and alachlor, although on fewer dates with significant differences. The mobility order of the applied chemicals was bromide > Atrazine > alachlor. The Atrazine apparent half-life was significantly longer in the Dry plots compared with the Wet plots. The retardation factor determined from the relative velocity of each herbicide to that of bromide was higher for alachlor than for Atrazine. This study identifies the impact that shrinkage cracks have for different moisture conditions on preferential transport of herbicides in claypan soils.

Aquat Toxicol. 2008 Jul 30; 88(4): 220-9
McCarthy ID, Fuiman LA

Contaminant exposure can affect development, growth, and behaviour of fish larvae, but its effect on rates of protein synthesis and protein degradation are not known. The aim of the present study was to examine the effects of a single pulsed dose aqueous exposure to environmentally realistic levels of two contaminants, Atrazine (0, 40 and 80mugl(-1)) and malathion (0, 1 and 10mugl(-1)), on growth and protein synthesis in red drum (Sciaenops ocellatus) larvae. Growth was assessed in terms of increase in length, weight, and protein content over an 8-day period following exposure. Rates of protein synthesis were measured by the flooding dose technique 2, 4, and 8 days after initial exposure to each contaminant by bathing larvae in seawater containing l-[2,6-(3)H] phenylalanine. Exposure to Atrazine had no effect on larval growth in length, but caused marginally significant declines in growth in weight (P=0.05) and protein content (P=0.06). However, protein synthesis rates were significantly higher for Atrazine-exposed larvae on days 4 (P=0.04) and 8 (P=0.01), suggesting an increase in rates of protein degradation. On day 8, the efficiency with which synthesised proteins contributed to growth was significantly lower (P=0.04) in Atrazine-exposed larvae. In contrast, malathion had no significant effects on growth in length or protein content, but there were significant decreases in growth in weight over 8 days. The only other significant effect of malathion was an increase in protein synthesis on day 2 for treated larvae relative to controls. Previous work [Alvarez, M.C., Fuiman, L.A., 2005. Environmental levels of Atrazine and its degradation products impair survival skills and growth of red drum larvae. Aquat. Toxicol. 74, 229-241] reported hyperactivity and increased metabolic rate in larval red drum exposed to Atrazine, indicating a clear energetic cost. Our results further emphasise the energetic cost of Atrazine exposure through elevated rates of protein synthesis and degradation resulting in reduced protein retention efficiency and lower growth rates. Overall, we conclude that exposure to Atrazine from surface water run-off can increase the energy requirements and the larval phase duration in red drum larvae, possibly resulting in reduced survival and recruitment in cohorts exposed to Atrazine.

Water Res. 2008 Jul; 42(13): 3315-26
Hildebrandt A, Guillamón M, Lacorte S, Tauler R, Barceló D

An environmental monitoring program was carried out to determine the impact of eight pesticides on the surface and groundwater quality of agricultural areas within the Ebro, Duero and Miño river basins. Three triazines and their desethyl degradation products, metolachlor and metalaxyl, were monitored during 18 months in 63 sites. Solid-phase extraction (SPE) using OASIS HLB 60mg cartridges and gas chromatography-mass spectrometry (GC-EI-MS) provided good analytical quality parameters and limits of quantification of 0.01mug/L. Environmental data were assessed using descriptive statistical analysis and multivariate data analysis with principal component analysis (PCA) to elucidate the relevant contamination patterns and provide a description of their seasonal trends, according to the pesticide application timing. Duero was the site with the highest frequency of detection and highest concentration levels, followed by the Ebro and Miño basins. The frequency of detection of the studied compounds, considering all surface and groundwater samples, was Atrazine>desethylAtrazine>simazine>desethylsimazine>metolachlor>desethylterbuthylazine>terbuthylazine>metalaxyl. Over all results, and taking into consideration the European Union (EU) maximum residual limit of pesticides in groundwater, only 12% of the results exceeded the 0.1mug/L limit. However, sporadic high levels up to 2.46mug/L in groundwater and 0.63mug/L in surface water were detected. PCA permitted to state that Duero and Ebro river basins were especially affected by a contamination pattern dominated by Atrazine, the Ebro river basin being occasionally affected by a contamination pattern dominated by simazine. Only trace levels were rarely detected in the Miño river basin. Groundwater levels were higher than surface water levels for the studied pesticides.

Pest Manag Sci. 2008 May 12;
Krutz LJ, Burke IC, Reddy KN, Zablotowicz RM

BACKGROUND: Enhanced Atrazine degradation has been observed in agricultural soils from around the globe. Soils exhibiting enhanced Atrazine degradation may be cross-adapted with other s-triazine herbicides, thereby reducing their control of sensitive weed species. The aims of this study were (1) to determine the field persistence of simazine in Atrazine-adapted and non-adapted soils, (2) to compare mineralization of ring-labeled (14)C-simazine and (14)C-Atrazine between Atrazine-adapted and non-adapted soils and (3) to evaluate prickly sida control with simazine in Atrazine-adapted and non-adapted soils.RESULTS: Pooled over two pre-emergent (PRE) application dates, simazine field persistence was 1.4-fold lower in Atrazine-adapted than in non-adapted soils. For both simazine and Atrazine, the mineralization lag phase was 4.3-fold shorter and the mineralization rate constant was 3.5-fold higher in Atrazine-adapted than in non-adapted soils. Collectively, the persistence and mineralization data confirm cross-adaptation between these s-triazine herbicides. In non-adapted soils, simazine PRE at the 15 March and 17 April planting dates reduced prickly sida density at least 5.4-fold compared with the no simazine PRE treatment. Conversely, in Atrazine-adapted soils, prickly sida densities were not statistically different between simazine PRE and no simazine PRE at either planting date, thereby indicating reduced simazine efficacy in Atrazine-adapted soils.CONCLUSIONS: Results demonstrate the potential for cross-adaptation among s-triazine herbicides and the subsequent reduction in the control of otherwise sensitive weed species. Copyright (c) 2008 Society of Chemical Industry.

Biotechnol Prog. 2008 May-Jun; 24(3): 588-92
Biglione N, Rodgers VG, Peeples TL

This work investigated the kinetic parameters of Atrazine mineralization by suspended cells of Pseudomonas sp. ADP in both shake flasks and spherical stirred tank batch reactors (SSTR). The degradation of Atrazine and growth of Pseudomonas sp. ADP were studied. Experiments were performed at different temperatures and stirring speeds in both reactors at varying initial concentrations of Atrazine. Cell growth and Atrazine concentration were monitored over time, and a Monod model with one limiting substrate was used to characterize the kinetic behavior. Temperature, stirring speed, and reactor type were all found to significantly affect the regressed Monod parameters. At 27 degrees C and 200 rpm, for the shaker flask experiments, mu max and Ks were determined to be 0.14 (+/-0.01) h-1 and 1.88 (+/-1.80) mg/L, respectively. At 37 degrees C, mu max and Ks increased to 0.25 (+/-0.05) h-1 and 9.59 (+/-6.55) mg/L, respectively. As expected, stirrer speed was also found to significantly alter the kinetic parameters. At 27 degrees C and 125 rpm, mu max and Ks were 0.04 (+/-0.002) h-1 and 3.72 (+/-1.05) mg/L, respectively, whereas at 37 degrees C and 125 rpm, mu max and Ks were 0.07 (+/-0.008) h-1 and 1.65 (+/-2.06) mg/L. In the SSTR the kinetic parameters mu max and Ks at room temperature were determined to be 0.12 (+/-0.009) h-1 and 2.18 (+/-0.47) mg/L, respectively. Although the mu max values for both types of reactors were similar, the shaker flask experiments resulted in considerable error. Error analysis on calculated values of Ks were found to impact estimates in Atrazine concentration by as much as two orders of magnitude, depending on the reactor design, illustrating the importance of these factors in reactor scale-up.

J Environ Qual. 2008 May-Jun; 37(3): 1086-100
Hancock TC, Sandstrom MW, Vogel JR, Webb RM, Bayless ER, Barbash JE

Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of Atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and Atrazine were applied at a Nebraska site the same year as sampling, and focused recharge coupled with the short time since application resulted in their movement in the unsaturated zone 9 m below the surface. At other sites where the herbicides were applied 1 to 2 yr before sampling, only degradates were found in soil water. Transformations of herbicides were evident with depth and during the 4-mo sampling time and reflected the faster degradation of metolachlor oxanilic acid and persistence of metolachor ethanesulfonic acid. The fraction of metolachlor ethanesulfonic acid relative to metolachlor and metolachlor oxanilic acid increased from 0.3 to >0.9 at a site in Maryland where the unsaturated zone was 5 m deep and from 0.3 to 0.5 at the shallowest depth. The flux of pesticide degradates from the deepest sites to the shallow ground water was greatest (3.0-4.9 micromol m(-2) yr(-1)) where upland recharge or focused flow moved the most water through the unsaturated zone. Flux estimates based on estimated recharge rates and measured concentrations were in agreement with fluxes estimated using an unsaturated-zone computer model (LEACHM).

J Environ Qual. 2008 May-Jun; 37(3): 848-57
Krutz LJ, Shaner DL, Accinelli C, Zablotowicz RM, Henry WB

Soil bacteria have developed novel metabolic abilities resulting in enhanced Atrazine degradation. Consequently, there is a need to evaluate the effects of enhanced degradation on parameters used to model Atrazine fate and transport. The objectives of this study were (i) to screen Colorado (CO) and Mississippi (MS) Atrazine-adapted and non-adapted soil for genes that code for enzymes able to rapidly catabolize Atrazine and (ii) to compare Atrazine persistence, Q(10), beta, and metabolite profiles between adapted and non-adapted soils. The atzABC and/or trzN genes were detected only in adapted soil. Atrazine's average half-life in adapted soil was 10-fold lower than that of the non-adapted soil and 18-fold lower than the USEPA estimate of 3 to 4 mo. Q(10) was greater in adapted soil. No difference in beta was observed between soils. The accumulation and persistence of mono-N-dealkylated metabolites was lower in adapted soil; conversely, under suboptimal moisture levels in CO adapted soil, hydroxyAtrazine concentrations exceeded 30% of the parent compounds' initial mass. Results indicate that (i) enhanced Atrazine degradation and atzABC and/or trzN genes are likely widespread across the Western and Southern corn-growing regions of the USA; (ii) persistence of Atrazine and its mono-N-dealkylated metabolites is significantly reduced in adapted soil; (iii) hydroxyAtrazine can be a major degradation product in adapted soil; and (iv) fate, transport, and risk assessment models that assume historic Atrazine degradation pathways and persistence estimates will likely overpredict the compounds' transport potential in adapted soil.

Commun Agric Appl Biol Sci. 2007; 72(2): 45-52
Ter Halle A, Wiszniowski J, Richard C

Photochemistry is one of the main ways of pollutants degradation in the environment. There is an obvious lack of data concerning the photostability of agrochemicals on plant foliage. We report here the first photodegradation study of a triketonic herbicide (sulcotrione) used as a substitute of Atrazine. To mimic surface Leaves, we used films made of carnauba grey wax or of cuticular wax extracted from maize Leaves. Under simulated solar light, sulcotrione was rapidly phototyzed. The phototysis was much faster on cuticular wax films than in aqueous phase. Moreover, the formulated sulcotrione (Mikado) disappeared even more quickly than the pure active ingredient. Sulcotrione mainly underwent an intramolecular cyclization. To validate these observations, sulcotrione and its main photoproduct were monitored after maize field treatment. The day after the treatment the main photoproduct was detected on the maize leaves and suLcotrione had already significantly disappeared. This experiment demonstrates that phototysis can be a relevant process in real conditions after field treatment.

Aquat Toxicol. 2008 May 30; 87(4): 215-26
Oka T, Tooi O, Mitsui N, Miyahara M, Ohnishi Y, Takase M, Kashiwagi A, Shinkai T, Santo N, Iguchi T

There is a growing international concern that commonly used environmental contaminants have the potential to disrupt the development and functioning of the reproductive system in amphibians. One such chemical of interests is the herbicide Atrazine. Effects of Atrazine on sex differentiation were studied using wild-type Xenopus laevis tadpoles and all-ZZ male cohorts of X. laevis tadpoles, produced by mating wild-type ZZ male to sex-reversed ZZ male (female phenotype). Stage 49 tadpoles were exposed to 0.1-100 ppb Atrazine or 0.27 ppb (1 nM) 17beta-estradiol (E(2)) until all larvae completed metamorphosis (stage 66). Metamorphosis, gonadal morphology and histology, CYP19 (P450 aromatase) mRNA induction, and hepatic vitellogenin (VTG) induction were investigated. Effects of Atrazine on VTG-induction were also assessed in vitro in primary-cultured X. laevis hepatocytes. Atrazine had no effect on metamorphosis of developing wild-type or all-male X. laevis larvae. Statistical increase in female ratios was observed in 10 and 100 ppb Atrazine groups in comparison with control group. While no hermaphroditic froglet was observed in all Atrazine groups. In ZZ males, sex reversal was induced by 0.27 ppb E(2), but not by Atrazine at concentrations of 0.1 and 1.0 ppb. In addition, neither P450 aromatase mRNA in the gonad nor hepatic VTG were induced by Atrazine. Furthermore, VTG was not induced by 1000 ppb Atrazine in primary-cultured hepatocytes. Our results indicate that female ratios in developing X. laevis tadpoles were increased by 10 and 100 ppb Atrazine under the present experimental conditions. While the other endpoints showed no effect in the range of 0.1-100 ppb Atrazine. These results suggest that effect of Atrazine on sexual differentiation was not caused by estrogenic action and has no induction ability of P450 aromatase gene in gonad.

Gen Comp Endocrinol. 2008 May 1; 156(3): 603-12
Stoker C, Beldoménico PM, Bosquiazzo VL, Zayas MA, Rey F, Rodríguez H, Muñoz-de-Toro M, Luque EH

Human and wildlife are exposed at critical periods of development to endocrine disruptor chemicals (EDC) that may be responsible for reproductive disorders. To test the hypothesis that in ovum exposure to EDC at a critical period for gonadal organogenesis alters post-hatching folliculogenesis and steroidogenesis in Caiman latirostris, we studied the impact of in ovum exposure to 17 beta-estradiol (E2), bisphenol A (BPA), endosulfan (END) and Atrazine (ATZ) on gonadal differentiation, follicular dynamics and circulating levels of steroid hormones in neonatal and juvenile caiman. Since C. latirostris is a species with temperature dependent sex determination, eggs were incubated at male (33 degrees C) or female (30 degrees C) producing temperatures and the effect of EDC was evaluated. Neonatal ovaries exhibited germ cells mainly located in clusters evidencing proliferative activity and type I to III follicles. Juvenile ovaries exhibited germ cells and advanced stages of pre-vitellogenic follicles. Prenatal exposure to the highest doses of E2 (1.4 ppm) or BPA (140 ppm) overrode male temperature effect on sex determination. Neonatal females produced by sex reversion lacked type III follicles, while females prenatally exposed to the lowest doses of E2 (0.014 ppm) and BPA (1.4 ppm) or ATZ (0.2 ppm) showed an increase in type III follicles. Juvenile caiman prenatally exposed to E2 or BPA showed an augmented incidence of multioocyte follicles. Neonatal female caiman exposed in ovum to E2 or BPA had higher estrogen serum levels whereas exposure to E2, BPA, ATZ and END decreased T levels. Present data demonstrates that exposure to EDC during gonadal organogenesis alters follicular dynamics and steroid levels later in life. These effects might have an impact on caiman fertility.

J Agric Food Chem. 2008 Apr 23; 56(8): 2595-602
Huang SB, Mayer TJ, Yokley RA

A multianalyte method is reported for the determination of Atrazine, simazine, propazine, and their respective dealkylated chlorotriazine metabolites; ametryn and prometryn and their respective dealkylated thiomethyltriazine metabolites; and S-metolachlor and its ethanesulfonic and oxanilic acid degradates in deionized, ground, surface, and finished drinking water. Water samples are analyzed using direct aqueous injection (DAI) liquid chromatography-electrospray ionization/mass spectrometry/mass spectrometry (LC-ESI/MS/MS). No preanalysis sample manipulation is required other than transfer of a small portion of sample to an injection vial. The lower limit of the method validation is 0.050 microg/L (ppb) for all analytes except 2,4-diamino-6-chloro- s-triazine (didealkylAtrazine, DDA, or G-28273). For this compound the LLMV is 0.50 microg/L (ppb). The overall mean procedural recoveries (and percent relative standard deviations) for all water types for all analytes ranged from 95 to 101% (4.5-11%). The method validation was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160.

Chem Res Toxicol. 2008 Apr; 21(4): 844-51
Dooley GP, Reardon KF, Prenni JE, Tjalkens RB, Legare ME, Foradori CD, Tessari JE, Hanneman WH

Atrazine (ATRA) is the most commonly applied herbicide in the United States and is frequently detected in drinking water at significant levels. After oral exposure, ATRA metabolism yields diaminochlorotriazine (DACT), an electrophilic molecule that has been shown to form covalent protein adducts. This research was designed to identify ATRA-induced protein adducts formed in the pituitary gland of ATRA-exposed rats and in DACT-exposed LbetaT2 rat pituitary cells. Immunohistochemistry showed diffuse cytoplasmic and nuclear staining in both pituitary sections and LbetaT2 cells indicating the formation of DACT protein adducts. Protein targets from both rat pituitaries and LbetaT2 cell culture were identified following two-dimensional electrophoresis (2DE), immunodetection, and matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. Western blots from both exposed rats and LbetaT2 cells revealed over 30 DACT-modified spots that were not present in control animals. Protein spots were matched to concurrently run 2DE gels stained with Sypro Ruby, excised, and in-gel-digested with trypsin. Mass spectrometry analysis of digest peptides resulted in the identification of 19 spots and 8 unique proteins in the rats and 21 spots and 19 unique proteins in LbetaT2 cells. The identified proteins present in both sample types included proteasome activator complex subunit 1, ubiquitin carboxyl-terminal hydrolase isozyme L1, tropomyosin, ERp57, and RNA-binding proteins. Each of these proteins contains active-site or solvent-exposed cysteine residues, making them viable targets for covalent modification by DACT.

Anal Bioanal Chem. 2008 May; 391(1): 345-52
Ghanem A, Bados P, Perreau F, Benabdallah R, Plagellat C, de Alencastro LF, Einhorn J

A multiresidue method has been developed to analyze Atrazine (ATZ), diuron (DIU), and their major degradation products, desethylAtrazine (DEA), desisopropylAtrazine (DIA), and dichlorophenylmethylurea in sewage sludge. Liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS-MS) allowed, in the multiple-reaction monitoring mode, the simultaneous analysis of these pesticides in only one run after their extraction with ethyl acetate-dichloromethane 90:10 (v/v) and a cleanup on a Florisil column. Stable isotopically labeled ATZ and DIU were used as internal standards to overcome matrix effects during the pesticide quantification. Using fortified samples, the method gave rise to 86-115% as mean recovery values depending on the analyte. Limits of detection (LODs) and of quantification (LOQs) ranging from 0.3 (DIA) to 1.5 (DEA) microg kg(-1) dw and from 0.4 (DIA) to 2.0 (DEA) microg kg(-1) dw, respectively, were sufficient to achieve the monitoring of these molecules in sludge from wastewater treatment plants of the Ile-de-France region.

Environ Sci Technol. 2008 Feb 15; 42(4): 1165-71
Shechter M, Chefetz B

Plant cuticles have been reported as highly efficient sorbents for organic compounds. The objective of this study was to elucidate the sorption and desorption behavior of polar and nonpolar organic compounds with the major structural components of the plant cuticle: the biopolymers cutin and cutan. The sorption affinity values of the studied compounds followed the order: phenanthrene > Atrazine > chlorotoluron > carbamazepine. A higher sorption affinity of phenanthrene and Atrazine to cutin was probably due to the higher level of amorphous paraffinic carbon in this biopolymer. Phenanthrene exhibited reversible sorption behavior and a high ratio of organic-carbon-normalized distribution coefficient (Koc) to carbon-normalized octanol-water partitioning coefficients (Kowc) with both biopolymers. This suggests that both biopolymers provide phenanthrene with a partition medium for hydrophobic interactions with the flexible long alkyl-chain moieties of the biopolymers. The low Koc/Kowc ratios obtained for the polar sorbates suggest that the polar sites in the biopolymers are not accessible for sorption interactions. Atrazine and carbamazepine exhibited sorption-desorption hysteresis with both sorbents, indicating that both sorbates interact with cutin and cutan via both hydrophobic and specific interactions. In general, the sorptive properties of the studied biopolymers were similar, signifying that the active sorption sites are similar even though the biopolymers exhibit different properties.

Arch Environ Contam Toxicol. 2008 Mar 6;
Bonnet JL, Bonnemoy F, Dusser M, Bohatier J

The potential toxicity of sulcotrione (2-[2-chloro-4-(methylsulfonyl)benzoyl]-1,3-cyclohexanedione) and mesotrione (2-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione), two selective triketonic herbicides, was assessed using representative environmental microorganisms frequently used in ecotoxicology: the eukaryote Tetrahymena pyriformis and the prokaryote Vibrio fischeri. The aims were also to evaluate the toxicity of different known degradation products, to compare the toxicity of these herbicides with that of Atrazine, and to assess the toxicity of the commercial herbicidal products Mikado((R)) and Callisto((R)). Toxicity assays involved the Microtox test, the T. pyriformis population growth impairment test, and the T. pyriformis nonspecific esterase activity test. For each compound, we report original data (IC(50) values) on nontarget cells frequently used in ecotoxicology. Analytical standards sulcotrione and mesotrione showed no toxic effect on T. pyriformis population growth but a toxic influence was observed on nonspecific esterase activities of this microorganism and on metabolism of V. fischeri. Most of the degradation products studied and the two commercial formulations showed a greater toxicity than the parent molecules. Compared with the effect of Atrazine, the toxicity of these triketonic herbicides was less than in T. pyriformis and greater than or the same as in V. fischeri. Additional work is needed to obtain a more accurate picture of the environmental impact of these herbicides. It will be necessary in future experiments to study the ecosystemic levels (aquatic and soil compartments) and to assess the potential toxicity of the newly discovered degradation products and of the additives accompanying the active ingredient in the commercial herbicidal formulations.

Huan Jing Ke Xue. 2007 Dec; 28(12): 2821-6
Wang J, Zhu LS, Xie H, Song Y, Sun RL, Zhang FD

To evaluate the difference of POPs Atrazine degradation dynamics in soils under different fertilization conditions, we set up an analysis method of the Atrazine residue in soils and studied residue dynamics of Atrazine in soils under a long-term located fertilization conditions. After extracted by surging with acetone, liquid-liquid partition and eluted through florisil, the residue of Atrazine in soils was detected by gas chromatogram with 63Ni-ECD. The minimum detectable quantity of Atrazine is 6.4 x 10(-12) g and the minimum detectable concentration is 6.4 x 10(-9) g x kg(-1) in the soil. The spiked recoveries of Atrazine with the three concentration of 0.11, 1.1, 11.0 mg x kg(-1) in soils are 91.41% +/- 4.36%, 93.58% +/- 4.54%, 90.35% +/- 3.59%, according with the request of pesticide residue analysis. The degradation of Atrazine in soil under a long-term located fertilization conditions was studied. The results show the degradation of Atrazine follows stair dynamic equation, and the degradation half-life of Atrazine in soils fertilized with CK, NPK, NPK + M, NPK + S are 20.6, 23.0, 28.5, 33.2 d, respectively. Subjected to analysis of LSR, NPK and organic fertilizers are obviously propitious to the degradation of Atrazine. The separate regression and stepwise regression analysis prove the degradation half-life of Atrazine in soils is well related with the content of alkaline nitrogen, organic matter and total nitrogen, and the coefficients are 0.9983, 0.9826 and 0.9521, respectively. Maybe the reason is that these soil nutrient substance offers enough the element carbon and nitrogen for action of microbe, and the higher action of microbe quickens the degradation of Atrazine in soils.

Environ Geochem Health. 2008 Apr; 30(2): 147-52
Mahía J, Martín A, Díaz-Raviña M

Extractable Atrazine and its metabolites (hydroxyAtrazine, deethylAtrazine and deisopropylAtrazine) were evaluated in agricultural soils from the temperate humid zone (Galicia, NW Spain) under laboratory conditions. The experiment was performed with five soils with different properties (organic C, soil texture and Atrazine application history), both unamended and treated with Atrazine at field application rate. Measurements of the Atrazine compounds were made at different time intervals (1, 3, 6, 9 and 12 weeks) during a 3-month incubation period. Results showed that only hydroxyAtrazine was detected in the extractable fraction of the unamended soils, with values remaining relatively constant throughout the incubation period. Atrazine addition notably increased the concentration of the parent compound and its degradation products; deisopropylAtrazine and hydroxyAtrazine were the main metabolites detected in the extractable fraction of the treated soils, whereas deethylAtrazine was not detected. After 7 days incubation, values of total extractable residues, expressed as percentage of initially added Atrazine, ranged from 75 to 86% (25-68% of Atrazine, 7-11% of hydroxyAtrazine and 9-57% of deisopropylAtrazine). The values decreased rapidly during the first 3 weeks of incubation, showing values of 2-8% in soils with higher Atrazine application and from 28 to 30% in soils with lower application history. At the end of the incubation, 2-8% of total extractable residues were still detected (0-4% of Atrazine, 2-3% of hydroxyAtrazine and 0-2% of deisopropylAtrazine), indicating a residual effect of Atrazine addition. These variations in the extractable fraction indicated that most added Atrazine was rapidly degraded, especially in soils with higher application history.