Persistence Of Atrazine In Soil Research Articles

Modeling Bioavailability Limitations of Atrazine Degradation in Soils

Pesticide persistence in soils is a widespread environmental concern in agro-ecosystems. One particularly persistent pesticide is atrazine, which continues to be found in soils and groundwater in the EU despite having been banned since 2004. A range of physical and biological barriers, such as sorption and mass-transfer into bacterial cells, might limit atrazine degradation in soils. These effects have been observed in experiments and models working with simplified systems. We build on that work by developing a biogeochemical model of the degradation process. We extended existing engineered system models by including refined representations of mass-transfer processes across the cell membrane as well as thermodynamic growth constraints. We estimated model parameters by calibration with data on atrazine degradation, metabolite (hydroxyatrazine) formation, biomass, and isotope fractionation from a set of controlled retentostat/chemostat experiments. We then produced site-specific model predictions for arable topsoil and compared them with field observations of residual atrazine concentrations. We found that the model overestimated long-term atrazine biodegradation in soils, indicating that this process is likely not limited by bioavailability or energetic constraints of microbial growth. However, sorption-limited bioavailability, could explain the long-term fate and persistence of the main degradation metabolite hydroxyatrazine. Future studies should seek alternative controls that drive the observed atrazine persistence in soil. This work helps to bridge the gap between engineered and natural systems, allowing us to use laboratory setups to gain insight into real environmental systems.

Combined pollution of copper nanoparticles and atrazine in soil: Effects on dissipation of the pesticide and on microbiological community profiles.

Copper nanoparticles (NCu) have been proposed as an antimicrobial agent in agriculture. Therefore, NCu may interact with numerous pollutants including pesticides. Little is known about the combined effects of NCu and pesticides in soil. This study aimed at assessing the impact of NCu combined with the herbicide atrazine (ATZ) on soil. We focused on assessing the adsorption and dissipation of ATZ in the presence of NCu and the changes in microbial community profiles. First, ATZ adsorption isotherms (described using the Freundlich equation) were evaluated. After that, soil samples were spiked with NCu (40-60 nm) at 0.05 and 0.15% w/w and ATZ (3 mg a.i kg-1) and incubated for 30 days. The results showed that ATZ adsorption is favored by the presence of NCu. On the other hand, NCu at 0.15% w/w caused a significant decrease in ATZ dissipation, increasing its half-life from 6 to 37 days. Microbial community profiles (bacteria, fungi and nitrifying bacteria) remained relatively stable throughout the evaluated period. Therefore, our findings suggest that NCu can increase the persistence of ATZ in soil, which may be mostly associated to physical-chemical interaction with soil particles more than a microbial impact.

The interaction between atrazine and the mineral horizon of soil: a spectroscopic study

PurposeIn this paper, an attempt was made to explain the long-lasting occurrence of atrazine in soil. Despite the fact that this herbicide has been banned in European Union 10 years ago, it is still detected in the environment.Materials and methodsSoil samples (organic and mineral horizon), SiO2 and Al2O3 sorbents were spiked with atrazine. The ultrasound-assisted extraction coupled with gas chromatography-electron capture detector was performed to establish the atrazine recovery depending on the type of soil horizon and sorbent. Fourier transform infrared spectroscopy (FTIR) analysis was conducted to determine the type of interactions between atrazine and sorbents.Results and discussionThe atrazine recovery was lower for the mineral horizon (15%) compared to the organic horizon (63%). This finding suggests an interaction between atrazine and the mineral components of soil. Therefore, attempts have been made to explain atrazine’s interaction with the main mineral components of soil, SiO2 and Al2O3, and to investigate the influence of pH on atrazine’s behaviour in soil. The atrazine recoveries were 86.5 and 10.7% for Al2O3 and SiO2, respectively. The obtained results demonstrated that the protonated atrazine exhibits stronger interactions with the soil mineral layer (recovery below 0.1%) in comparison to molecular form of atrazine (recovery 86%). FTIR results suggested interactions between atrazine and SiO2. FTIR analysis revealed that 1,3,5-azidine ring interacts with SiO2 molecule.ConclusionsIn acidic soil, atrazine remediation is limited, especially if the soil contains minerals with high SiO2 contents. This situation may cause the long-lasting persistence of atrazine in soil.

Field dissipation kinetics of atrazine in soil and post-harvest residues in winter maize crop under subtropical conditions

The growing awareness of environmental and health problems due to increased use of pesticides has led to the implementation of various monitoring programmes. Thus, to monitor residues in crops, dissipation studies were conducted of atrazine in the soil of winter maize in field conditions under the subtropical climatic zone of the Tarai region of India. A maize field was treated with atrazine at 2.0 and 4.0 kg a.i. ha−1 as pre-emergent herbicide. The degradation pattern of atrazine indicated correspondence to monophasic first-order kinetics in soils. The persistence of atrazine in soil was more in higher rate (135 days) compared with lower (100 days) application rate. The half-life values calculated to be 16.4 and 20.8 days at lower and higher application rate, respectively. Detector response was linear within 0.01–1.0 μg mL−1 concentration range at per cent relative standard deviation 2.07%. The instrument limit of detection was 1 ng mL−1 and limit of quantification for soil, straw and cobs 0.005, 0.007 and 0.006 μg g−1, respectively. The average recoveries of atrazine from soil, cobs and straw samples were found between 86.8–90.0%, 88.0–91.6% and 93.2–95.6%, respectively. At both the application rates, no residues have been observed in soil, maize cobs (seeds) and straw at the time of harvest.

Atrazine degradation in soil: effects of adjuvants and a comparison of three mathematical models

There are few reports on the effects of spray adjuvants on pesticide persistence. The role of three adjuvants used with atrazine on the herbicide's degradation in soil was examined. Three mathematical models were used to describe pesticide disappearance from soil: pseudo-first-order kinetics, the non-linear Gustafson-Holden model and the biexponential function. A mixture of atrazine with Atpolan 80 EC significantly inhibited herbicide soil degradation (DT50 = 78 days), while Adpros 85 SL and Break-Thru S 240 (DT50 = 25 and 24 days respectively) had little effect (DT50 = 22 days, atrazine alone). These results suggest that adjuvant can be a factor in field persistence. DT50 values obtained using the Gustafson-Holden and biexponential models were similar. Only the biexponential model requires an iterative method. A significant effect of one adjuvant on atrazine persistence in soil was observed. The biexponential model best described the disappearance of atrazine in the soil, as indicated by the values of R(2) and RMS and the relative concentration of the herbicide in the soil.

Field Persistence of Repeated Use of Atrazine in Sandy Clay Loam Soil under Maize

Field experiments were conducted with maize as a test crop during 2006-2009 to study the effect of atrazine on its persistence and residue in soil and crop produce as influenced by the quantity of application and seasons. The treatments imposed were control, 0.5 and 1.0 kg ai of atrazine ha-1 and were replicated thrice in randomized block design. For residue analysis, the soil samples were collected at periodical intervals from 0 day to harvest and the crop produce were also sampled at post harvest. The atrazine was determined using GC equipped with FID detector. Persistence of atrazine in soil showed a gradual degradation with advancement in crop growth. The application of atrazine at recommended dose left no residue in the soil whereas the application of atrazine at double the recommended dose recorded 0.056 ppm of atrazine residue in the post harvest soil. Pooled data showed that the dissipation of atrazine was biphasic in nature and the degradation was faster at higher dose of application than at the lower dose. Degradation of atrazine in soil followed first order kinetics and the mean half life of atrazine was 21.54 days. Persistence of atrazine was also influenced by the season and years of application.

Mineralization of 14C-atrazine in an entic haplustoll as affected by selected winter weed control strategies

The effect of winter weed control (WWC) management on 14C-atrazine (6-chloro- N 2-ethyl- N 4-isopropyl-1,3,5-triazine-2,4-diamine) mineralization was investigated in an Entic Haplustoll in Argentina. Three WWC managements were selected: Chemical Fallow (CF) and Cereal Cover Crop (CCC), both under no-tillage, and Reduced Tillage (RT) with chisel and moldboard plow. Soil was sampled at two depths: 0–5 and 5–10 cm, to evaluate the soil stratification induced by the tillage system. To distinguish differences in atrazine degradation in soils with and without previous history of atrazine application two crop sequences were selected: continuous soybean [ Glycine max L., Merr.] (CS) without previous atrazine exposure, and soybean–maize ( Zea mays L.) rotation (SM) with atrazine application every winter and in alternate springs. The release of 14C-CO 2 during laboratory incubations of soils treated with ring labelled 14C-atrazine was determined. Soil organic matter (SOM) distribution was determined with depth and among three soil size fractions: 200–2000 μm, 50–200 μm and <50 μm. Previous atrazine application enhanced atrazine degrading microorganims. Atrazine mineralization was influenced by both WWC management and the tillage system. Chemical fallow showed the highest atrazine mineralization in the two crop sequences. Depth stratification in atrazine degradation was observed in the two WWC treatments under the no-tillage. Depth stratification in the content of soil organic C and relative accumulation of organic C in coarsest fractions (200–2000 and 50–200 μm) were observed mainly in no-till systems. Depth stratification of atrazine degrading activity was mainly correlated to the stratification of fresh organic matter associated with the coarsest fractions (200–2000 μm). Atrazine persistence in soil is strongly affected by soil use and management, which can lead to safe atrazine use through selection of appropriate agricultural practices.

Application of 14C-most-probable-number technique to enumerate atrazine-degrading microorganisms in soil

The size and activity of atrazine-degrading populations are among the factors controlling atrazine persistence in soil. Populations of atrazine-degrading microorganisms in surface and subsurface soils were enumerated by the 14C-most-probable-number ( 14C-MPN) technique using [ 14C- ethyl]-atrazine or [U- 14C- ring]-atrazine in C- or N-limited media. The [ 14C- ethyl] atrazine served as a potential carbon source for a larger number of microorganisms than [U- 14C- ring]-atrazine. Populations of atrazine-degrading microorganisms using [ 14C- ethyl]-atrazine as a carbon source ranged from 4670 to 31,930 cells g −1 of surface soil, but were 1050 cells g −1 in a subsurface sediment. The size of these [ 14C- ethyl]-atrazine-degrading microbial populations were positively correlated ( r 2=0.81) to mineralization of [ 14C- ethyl]-atrazine added to soil, which suggests that atrazine-degrading populations may serve as an indicator of atrazine persistence in the soil environment. Populations degrading [U- 14C- ring]-atrazine ranged from 130 to 1630 cells g −1 soil in C-limited media and from 19 to 10,530 cells g −1 soil in N-limited media. Population size and mineralization activity were generally increased by the frequency of atrazine use, suggesting that long-term exposure encourages microbial adaptation and growth.

Simulation of the persistence of atrazine in soil at different sites in Portugal

SummaryThe effects of soil temperature and soil moisture content on the rates of degradation of atrazine, were measured in the laboratory in soils from different sites in Portugal. Persistence of atrazine was measured in the same soils in the field during the spring and summer of 1984, 1985, 1986 and 1987. Weather records from the different sites, measured during the periods of the field experi ments, were used in conjunction with appropriate constants derived from the laboratory data in a computer program to simulate persistence in the field. The model generally overestimated the ob served soil residues, particularly during the first 7–14 days after application. The fit from the model was good from day 14 to the end of the experiments.

Assessing atrazine persistence in soil following a severe drought

Much of the corn production region in the US, including Michigan, experienced a severe drought during the 1988 growing season. The very little rainfall coupled with temperatures above normal created extremely dry soil conditions during the period when soil moisture is usually adequate in Michigan raised concern about herbicide carryover. Atrazine (2-chloro-40(ethylamino)-6-(isopropylamino)-s-triazine) is the most widely used herbicide with potential to persist in sufficient quantity to injure sensitive rotational crops. Atrazine is degraded in soil by both chemical hydrolysis and microbial breakdown with these processes occurring much more rapidly under conditions of adequate soil moisture and relatively warm temperature. It is generally accepted that the risk of atrazine carryover is greater following a year of low rainfall, since microbial activity is favored by adequate soil moisture. The 1988 drought created a critical need for an assessment of atrazine concentration in soil to advise producers on crop management options related to atrazine sensitive crops. The objectives of this study were to assess: (1) atrazine residue levels in Michigan soils following the 1988 drought, and (2) the suitability of the immunoassay technique over a wide variety of soils.

Interactions in the fate of chemicals in terrestrial systems

In outdoor lysimeters, [ 14C]atrazine (0.9 mg/kg dry soil), [ 14C]atrazine combined with the detergent n-dodecylbenzenesulfonate (0.9 and 10 mg/kg, respectively), [ 14C] n-dodecylbenzenesulfonate (10 mg/kg), and [ 14C] n-dodecylbenzenesulfonate combined with atrazine (10 and 0.9 mg/kg, respectively) were applied to soils. Maize was grown in the first year and barley in the second year. n-Dodecylbenzenesulfonate increased the mobility of atrazine and its metabolites in soil as well as its leaching into water, its uptake by maize plants, and its volatilization from soil. Atrazine had a negative influence on mineralization, mobility in soil, leaching, plant uptake by both species, and binding rates of radiocarbon derived from the surfactant in soil and plants. The results were confirmed by short-term laboratory tests. Whereas the effects of the detergent on the fate of atrazine and its conversion products were apparent only in the first growing season, those of atrazine on the fate of detergent-derived residues could also be observed in the second year due to the persistence of atrazine in soil.

Atrazine persistence in soil and transport in surface and subsurface runoff from plots in the coastal plain of the southern united states

This study evaluated the persistence of atrazine in the soil and movement in surface runoff and shallow phreatic flow. Atrazine persisted in the surface 10 cm of soil for over 4 months. However, it could not be detected at greater depths after approximately 2 months. Persistence (time) in the soil did not vary significantly with application rate. Initial concentrations in the soil did, however, vary significantly. Initial atrazine concentrations in the soil for the 4.48 kg ha −1 application rate were approximately twice those at the 2.24 kg ha −1 rate. Atrazine was not detected in significant amounts in surface runoff after 26 days and was not observed at any time in the subsurface flow from the treated area. Total losses for the 2 rates in 1974 and 1975 ranged from 0.22–2.24%. Concentrations in the soil and surface runoff were directly related to application rates.