Atrazine In Soil Research Articles

Effect of H3PO4-modified biochar on the fate of atrazine and remediation of bacterial community in atrazine-contaminated soil

The application of chemically modified biochar is a promising strategy for the remediation of contaminated (e.g., pesticides) soil. In this study, H3PO4 was used to modify peanut shell to improve the remediation performance of biochar. Surface area (980.19 m2/g), pore volume (0.12 cm3/g), and the functional groups (OH, CO, and phosphorus-containing groups) on the biochar were increased by H3PO4 treatment. The sorption experimental data were well fitted by Freundlich model, while the sorption affinity (Kf) of H3PO4 modified biochar (PBC) for atrazine was 128 times greater than that of the untreated biochar (BC) in the aquatic systems. The Kf values of PBC-amended soil to atrazine were increased by 13.57 times than that of single soil. The strong sorption of PBC on atrazine delayed the degradation of atrazine in soil, and the residual percentage of atrazine in soil and soil-PBC mixture were 4.90% and 71.44% at the end of 60-day incubation, with the degradation half-life increased from 13.3 to 121.6 d. The analysis of high-throughput sequencing results showed that atrazine reduced the diversity of soil microbial community, but the abundance of microorganisms with degradation function increased and became dominant species. The addition of PBC in soil accelerated the microbial remediation of atrazine stress, which may promote the soil nitrogen cycle. Therefore, amendment of atrazine contaminated soil with PBC can reduce the environmental risk of atrazine and benefit the soil microbial ecology.

Toxicological effects, environmental behaviors and remediation technologies of herbicide atrazine in soil and sediment: A comprehensive review

Atrazine has become one of the most popular applied triazine herbicides in the world due to its high herbicidal efficiency and low price. With its large-dosage and long-term use on a global scale, atrazine can cause widespread and persistent contamination of soil and sediment. This review systematically evaluates the toxicological effects, environmental risks, environmental behaviors (adsorption, transport and transformation, and bioaccumulation) of atrazine, and the remediation technologies of atrazine-contaminated soil and sediment. For the adsorption behavior of atrazine on soil and sediment, the organic matter content plays an extremely important role in the adsorption process. Various models and equations such as the multi-media fugacity model and solute transport model are used to analyze the migration and transformation process of atrazine in soil and sediment. It is worth noting that certain transformation products of atrazine in the environment even have stronger toxicity and mobility than its parent. Among various remediation technologies, the combination of microbial remediation and phytoremediation for atrazine-contaminated soil and sediment has wide application prospects. Although other remediation technologies such as advanced oxidation processes (AOPs) can also efficiently remove atrazine from soil, some potential problems still need to be further clarified. Finally, some related challenges and prospects are proposed.

Evaluation of the effectiveness of bioaugmentation and biostimulation in atrazine removal in a polluted matrix using degradation kinetics

ABSTRACT The objective of the present study was the restoration of sterilized soil contaminated with atrazine (5.52 mg kg−1) using atrazine-degrading bacteria, biochar, and poultry manure amendments. The atrazine-degrading bacterium was purified from a mixed culture isolated from a long-history atrazine soil, and identified as Alcaligenes sp. strain AZUHUB-A31-CH52 ND4 based on the 16S rRNA sequence. After 35-day bioremediation, the sterile soil inoculated with Alcaligenes sp. and amended with biochar or poultry manure improved atrazine removal efficiency (98–99%) while the soil containing only atrazine degraders resulted in the lowest atrazine removal (78%). The atrazine degradation kinetics in the amended and unamended soils adequately fit the double first-order in parallel (DFOP) model given the goodness of fit parameters (high r2 (0.9703–0.9997) and low AICc (−106.30 to −28.92) values. The DFOP model also predicted that DT50 (half-life) in all treatments was < 1 day (0.03–0.13 day) at a fast dissipation rate k1 (5.422–20). The DT90 (90% atrazine removal) estimated by DFOP ranged between 23–94 days. The results demonstrated that low-cost bio-waste could offer a sustainable and eco-friendly approach for the reclamation of soils contaminated with atrazine.

Biochar alleviated the toxicity of atrazine to soybeans, as revealed by soil microbial community and the assembly process

Atrazine has a detrimental effect on soybean growth in corn-soybean rotation systems. A knowledge gap exists regarding how rhizosphere microbial interactions respond to atrazine stress, and specifically, whether they may alleviate the detriment of atrazine on soybeans, this serving as a target to alleviate the adverse impact. Biochar are widely used for remediation in herbicide contamination soil, however, little is known about how biochar fuels the microbiomes in rhizosphere to improve soybean performance. We investigated the response of the microbial community to atrazine stress with and without biochar application to soybean cultivation in a greenhouse experiment. Atrazine had detrimental effects on soybeans and nodules, reshaping the microbial community in both the bulk and rhizosphere soil. Biochar application was able to ameliorate atrazine effects on soybean and nodule activity, with an increase in competition among microbes in the soybean rhizosphere soils. Biochar favored the probiotics such as the bacteria Lysobacter, Paenarthrobacter, and Sediminibacterium in the rhizosphere soils. The relative abundance of Lysobacter exhibited strong-negative correlations with potential pathogens. Elastic net regression with bioindicators and environmental factors accurately predicted the residual content of atrazine in soil. Collectively, our results provide a practical strategy of using biochar to improve soil quality for corn-soybean rotation that is contaminated with residual atrazine. Overall, beneficial plant microbes and changes in microbial interactions and assembly processes in the soybean rhizosphere are capable of alleviating atrazine stress on soybean growth.

Optimizing the Effect of pH and Temperature on Atrazine Degradation by Bacillus safensis strain BUK_BCH_BTE6 an Efficient Atrazine Tolerating Bacteria from an Agricultural Soil in Kura Local Government Area of Kano State, Nigeria

The widespread and long term use of atrazine results in high residue levels of atrazine in soil, which further causes water contamination, it is considered as an endocrine disruptor and is potentially carcinogenic. Microbial degradation of herbicide represents a time cost effective way of eco-restoration. This research was aimed at isolating and characterizing bacteria capable of degrading and utilizing atrazine as a sole carbon source. An enrichment method was used to isolate the bacteria on mineral salt media (MSM) following serial dilution. The isolate was identified morphologically, biochemically and molecularly as Bacillus safensis strain BUK_BCH_BTE6 based on 16S rRNA gene sequence and molecular phylogenetic analysis. The effect of pH and temperature on the degradation of atrazine was studied in MSM medium supplemented with atrazine as sole carbon source. Growth and degradation of atrazine in this isolate was optimal at pH 7.5 and temperature of 35 °C. Bacillus safensis is highly efficient in atrazine degradation with an optimum range of pH and temperature. Bacillus safensis could be a suitable candidate for bioremediation of atrazine polluted sites.

Impacts of earthworm casts on atrazine catabolism and bacterial community structure in laterite soil

Atrazine accumulation in agricultural soil is prone to cause serious environmental problems and pose risks to human health. Vermicomposting is an eco-friendly approach to accelerating atrazine biodegradation, but the roles of earthworm cast in the accelerated atrazine removal remains unclear. This work aimed to investigate the roles of earthworm cast in promoting atrazine degradation performance by comprehensively exploring the change in atrazine metabolites and bacterial communities. Our results showed that earthworm cast amendment significantly increased soil pH, organic matters, humic acid, fulvic acid and humin, and achieved a significantly higher atrazine removal efficiency. Earthworm cast addition also remarkably changed soil microbial communities by enriching potential soil atrazine degraders (Pseudomonadaceae, Streptomycetaceae, and Thermomonosporaceae) and introducing cast microbial degraders (Saccharimonadaceae). Particularly, earthworm casts increased the production of metabolites deethylatrazine and deisopropylatrazine, but not hydroxyatrazine. Some bacterial taxa (Gaiellaceaea and Micromonosporaceae) and humus (humic acid, fulvic acid and humin) were strongly correlated with atrazine metabolism into deisopropylatrazine and deethylatrazine, whereas hydroxyatrazine production was benefited by higher pH. Our findings verified the accelerated atrazine degradation with earthworm cast supplement, providing new insights into the influential factors on atrazine bioremediation in vermicomposting.

Layer-by-Layer Encapsulation of Herbicide-Degrading Bacteria for Improved Surface Properties and Compatibility in Soils.

E. coli cells overexpressing the enzyme atrazine chlorohydrolase were coated using layer-by-layer self-assembly. The polymeric coating was designed to improve the surface properties of the cells and create positively charged, ecologically safe, bio-hybrid capsules that can efficiently degrade the herbicide atrazine in soils. The physio-chemical properties of the bacteria/polymer interface were studied as a function of the polymeric composition of the shell and its thickness. Characterization of cell viability, enzyme activity, morphology, and size of the bio-capsules was done using fluorescence spectroscopy, BET and zeta potential measurements and electron microscopy imaging. Out of several polyelectrolytes, the combination of polydiallyldimethylammonium chloride and polysodium 4-styrenesulfonate improved the surface properties and activity of the cells to the greatest extent. The resulting bio-hybrid capsules were stable, well-dispersed, with a net positive charge and a large surface area compared to the uncoated bacteria. These non-viable, bio-hybrid capsules also exhibited a kinetic advantage in comparison with uncoated cells. When added to soils, they exhibited continuous activity over a six-week period and atrazine concentrations declined by 84%. Thus, the concept of layer-by-layer coated bacteria is a promising avenue for the design of new and sustainable bioremediation and biocatalytic platforms.

Atrazine behavior in an agricultural soil: adsorption–desorption, leaching, and bioaugmentation with Arthrobacter sp. strain AAC22

PurposeTo evaluate atrazine behavior in an agricultural soil (adsorption–desorption, leaching) and the effects of bioaugmentation with the Arthrobacter sp. strain AAC22, as a soil remediating strategy.Material and methodsAn agricultural soil with a history of atrazine application was used. Equilibrium batch experiments allowed the investigation of the adsorption–desorption of atrazine at different soil depths, while the atrazine leaching potential was assessed using disturbed soil columns. Arthrobacter sp. strain AAC22 was selected for bioaugmentation, to remove atrazine in soil microcosms. Removal efficiency was determined by a bioassay with oat seeds.Results and discussionAdsorption and desorption isotherms of atrazine at different soil depths were well described by the Freundlich equation (R2 > 0.99 and R2 > 0.98, respectively). The Freundlich constant (Kf) and desorption coefficient (Kfd1–3) decreased and increased, respectively, as soil depth increased. The Kf and Kfd1–3 values were correlated positively to organic carbon (r = 0.97) and negatively to pH (r = − 0.93). In this soil, 70.2% of atrazine applied (2.5 kg ha−1) was recovered in the leachate and 7.6% remained in the soil column. The higher atrazine concentration leached can be explained by the negative hysteresis of adsorption–desorption in this soil. Bioaugmentation with AAC22 enhanced atrazine removal being nearly 70% after 2 days of treatment, and it was almost complete (> 99%) after 8 days. A bioassay demonstrated that bioaugmentation was successful and toxic by-products were not detected.ConclusionThe adsorption–desorption and leaching experiments demonstrated the high mobility of the atrazine in the study soil. The bioaugmentation using the AAC22 strain is an effective strategy for atrazine removal in polluted soils.

Leaching behaviour of atrazine and fipronil in sugarcane trash ash mixed soils

ABSTRACT Crop residue ashes exhibit significant capacity to adsorb pesticides and affect their adsorption behaviour in soils. The present study evaluated the effect of sugarcane trash ash (STA), the third most important crop whose residues are burnt in fields in India, on atrazine and fipronil leaching behaviour in three sugarcane growing soils. The STA reduced downward mobility of atrazine in soils but, effect varied with the soil type. No atrazine residues were detected in the leachate. Atrazine was fairly mobile in the sandy loam soil than the loam and the clay loam soils and increasing leaching intensity from 64 to 128 mm, further increased herbicide’s downward mobility. Significant atrazine degradation was observed during leaching process and 38–43, 1.5–12.5 and 27–41% of column applied atrazine was degraded in the silty clay loam, the sandy clay loam and the loam soils, respectively. Higher atrazine degradation in the clay loam and the loam soils was attributed to slow water percolation rate and longer time to complete leaching process. Hydroxyatrazine, deethylatrazine and deisopropylatrazine metabolites of atrazine were detected in the soil samples, but their amounts varied in different treatments. Compared to atrazine, fipronil was highly retained in the surface layer (0–5 cm) in the control and STA-mixed soil columns and no fipronil was detected in the leachate. Trash burning is a regular practice; therefore, continuous mixing of STA in soils can reduce leaching of mobile pesticides applied in sugarcane crop. This study has implications in identifying the role of crop residue burning on fate of pesticides applied in soils.

Mechanism for various phytotoxicity of atrazine in soils to soybean: Insights from soil sorption abilities and dissolved organic matter properties

The pollutants in soils with different physicochemical properties usually exhibit various phytotoxicity due to their diverse environmental behavior. However, it is not clear that some components of dissolved organic matter (DOM) in soil affect the bioavailability of pollutants. In this study, the different phytotoxicity of atrazine in two different soils, black soil (BS) and yellow brown earth (YBE), to soybeen seedlings was investigated, and the potential mechanism were further discussed by examining the adsorption properties of atrazine with BS and YBE as well as the fluorescent characteristic variation of these two kinds of DOM extracted from BS and YBE during binding with atrazine. The results suggest that atrazine showed different phytotoxicity to soybean seedlings grown in BS and YBE. Specifically, the EC50 of atrazine on plant height and root length of soybean seedling in BS were 23.44 mg kg−1 and 54.29 mg kg−1, while those in YBE were 12.79 mg kg−1 and 21.48 mg kg−1. The adsorption amounts of BS and YBE was 41.56 mg kg−1 and 32.95 mg kg−1. In addition, 3D-EEM showed that humic acid-like substances were the main components of DOM in the two soils. With the increase of atrazine concentration, the fluorescence of these two kind of DOM was gradually quenched, but DOM-BS had a faster quenching rate. FT-IR showed that DOM-BS contained more polysaccharides and richer lipophilic groups. Meanwhile, the results of PARAFAC found that DOM-BS was easier to combine with atrazine. The findings of this study are significant to reveal phytotoxicity of atrazine in BS and YBE. The above results are helpful to better understand the components of DOM in different soils and their different role in regulating the environmental behavior and phytotoxicity of organic pollutants.

Endophytic bacterium CIMAP-A7 mediated amelioration of atrazine induced phyto-toxicity in Andrographis paniculata

The presence of atrazine, a triazine herbicide, and its residues in agriculture soil poses a serious threat to human health and environment through accumulation in edible plant parts. Hence, the present study focused on atrazine induced stress amelioration of Andrographis paniculata, an important medicinal plant, by a plant growth promoting and atrazine degrading endophytic bacterium CIMAP-A7 inoculation. Atrazine has a non-significant effect at a lower dose while at a higher dose (lower: 25 and higher: 50 mg kg−1) 22 and 36% decrease in secondary metabolite content and plant dry weight of A. paniculata was recorded, respectively. Endophyte CIMAP-A7 inoculation significantly reduced atrazine soil content, by 78 and 51% at lower and a higher doses respectively, than their respective control treatments. Inoculation of CIMAP-A7 exhibited better plant growth in terms of increased total chlorophyll, carotenoid, protein, and metabolite content with reduced atrazine content under both atrazine contaminated and un-contaminated treatments. Atrazine induced oxidative stress in A. paniculata was also ameliorated by CIMAP-A7 by reducing stress enzymes, proline, and malondialdehyde accumulation under contaminated soil conditions than un-inoculated treatments. Furthermore, the presence of atrazine metabolites deisopropylatrazine (DIA) and desethylatrazine (DEA) strongly suggests a role of CIMAP-A7 in mineralization however, the absence of these metabolites in uninoculated soil and all plant samples were recorded. These findings advocate that the amelioration of atrazine induced stress with no/least pesticide content in plant tissues by plant-endophyte co-interactions would be efficient in the remediation of atrazine contaminated soils and ensure safe crop produce.

Phytoremediation potential of three terrestrial plant species for removal of atrazine, azoxystrobin, and imidacloprid

Pesticides can move off-target resulting in contamination of sensitive water bodies and causing adverse effects on inhabiting species. Through best management practices, such as the implementation of vegetative buffer strips, off-target movement of pesticides can be decreased, and compound degradation can be increased via phytoremediation. In this study, blueflag iris (Iris versicolor), broomsedge (Andropogon virginicus) and switchgrass (Panicum virgatum) were planted in soil treated with one of three commonly used pesticides. At 28, 56 and 112 days after treatment (DAT), plants were destructively harvested and analyzed for pesticide residue in soil and above-ground and below-ground vegetation using high-performance liquid chromatography (HPLC). Relative to the amount of pesticide found in planted pots compared to non-planted pots, I. versicolor was found to reduce greater atrazine in soil compared to non-planted pots at 112 DAT by 58.7%. I. versicolor was also the most capable of reducing azoxystrobin, by 86.9% compared to non-planted pots, from the soil at 112 DAT. At the same sampling time, I. versicolor and P. virgatum reduced greater imidacloprid from soil by 62.5% and 64.3% compared to non-planted pots, respectively. This information supports the recommendation for establishment of diverse plant species for optimization of phytoremediation capacities. Novelty statement While research has found that plants can absorb and remediate synthetic chemicals, this practice is only sustainable if used with native plants that require low maintenance and are tolerant to the applied substances. Various previous studies observe plants that are fast-growing, tolerant to environmental conditions, require low-maintenance, and are hardy. However, these plant species are not always suitable for any location and are often considered invasive and/or weed-like. The present research initiates a list of plant species which can be used within the southeastern United States and similar areas to phytoremediate commonly used pesticides atrazine, azoxystrobin, and imidacloprid and prevent off-target movement.

Comparative evaluation of industrial hemp varieties: Field experiments and phytoremediation in Hawaii

Industrial hemp (Cannabis sativa L.) is a fast-growing and high biomass producing plant species with wide usage of its materials such as fiber, food, and fuel. There are many varieties containing low concentration of tetrahydrocannabinol (THC). In the present study, it assessed the agricultural feasibility of three industrial hemp varieties with different water management and nitrogen fertilizer treatments, and determined the best ones to cultivate in Hawaii, then evaluated the effects of plant density on the yield and the potential phytoremediation for the herbicide atrazine. The field experiments indicated that it was difficult to grow the variety F75 in Hawaii with a final weight of 13 g and did not live for the full growth season. However, the subtropical fiber hemp variety CHG grew to height of about 190 cm and its weight varied from 150 g to 280 g between two planting densities (100 plants m−2 and 28 plants m−2, respectively). The subtropical seed hemp variety CHY was intermediate at a mean height and weight of about 130 cm and 130 g, respectively. Estimated crop yields were 19 tons acre-1 year-1 (dry weight) for CHG stalks that could be used for building construction and 16 tons acre-1 year-1 (dry weight) for leaves could be used as animal forage. Approximately, 1.7 tons of seeds could be harvested per acre per year from variety CHY. Little water consumption (10 mm week-1) was needed, which corresponds with drought resistance of CHG variety. Use of nitrogen fertilizer at a rate of 100 kg ha-1 did not improve growth of CHG variety more than the existing nitrogen levels in the soil. Phytoremediation potential of industrial hemp was also assessed by field pot studies, in which field soils were fortified with 0, 0.25 and 0.50 mg kg-1 of atrazine. The half-life (t1/2) of atrazine in hemp watered pots was 15 days, whereas t1/2 was approximately 50 and 28 days in the no plant non-watered pots and the no plant watered pots, respectively, suggesting the degradation of atrazine in soils showed a higher efficiency planted with hemp under water irrigation condition. The CHG plants accumulated atrazine from soils, and the enrichment factor in CHG was increased over the course of 28 days (from 0.22 %–0.31 % to 0.63 %–0.89 %), then decreased after 49 days (0.28 %–0.30 %). Overall, these findings revealed that industrial hemp plants were useful for phytoremediation of soils contaminated with atrazine.

Soil bacterial community dynamics following bioaugmentation with Paenarthrobacter sp. W11 in atrazine-contaminated soil

Atrazine is one of the most widely used herbicides, however it and its metabolites cause widespread contamination in soil and ground water. Bioaugmentation is an effective method for remediation of environmental organic pollutants. High-throughput sequencing provides an important tool for understanding the changes of microbial community and function in response to pollutants degradation based on bioaugmentation. In this study, the effect of biodegradation with Paenarthrobacter sp. W11 and the change of microbial community during atrazine degradation were investigated. The results showed that bioaugmentation significantly accelerated the degradation rate of atrazine in soil and reduced the toxic effect of atrazine residues on wheat growth. The extra available NH4+ through atrazine mineralization could serve as a nitrogen source to increase microbial numbers. High-throughput sequencing further revealed that the microbial community restored a new balance. The function of microbial community predicted by PICRUSt2 suggested that the biodegradation process of atrazine affected not only the atrazine degradation pathway, but also the nitrogen metabolism pathway. Methylobacillus and Pseudomonas were considered as the most important indigenous atrazine-degrading microorganisms, because their relative abundances were positively correlated with the relative abundance of Paenarthrobacter and atrazine degradation pathway. This study provides insight into the cooperation between indigenous microorganisms and external inoculums on atrazine degradation process.

Dissipation, residue, dietary, and ecological risk assessment of atrazine in apples, grapes, tea, and their soil.

Atrazine is one of the most used herbicides in China. It is a persistent organic pollutant but has been widely used on Chinese farmlands for a long time. To assess its dietary and ecological risks to human and environment, in this study, atrazine residues were extracted with acetonitrile and then plant samples were detected with gas chromatography coupled with mass spectrometry (GC-MS) and soil samples were determined with gas chromatography coupled with nitrogen-phosphorus detector (GC-NPD). The limit of quantification (LOQ) of the method was 0.01 mg/kg for all matrices. The recoveries ranged from 82.0 to 105.4% for plant samples and 75.6 to 85.6% for soil samples. The final residues of atrazine in all plant samples were lower than LOQ. Dietary risk assessment suggested that under good agricultural practices (GAP) conditions, intake of atrazine from apples, grapes, and tea would exhibit an acceptably low health risk on consumers. However, the final residues of atrazine in soil samples were <0.01-9.2 mg/kg, and the half-lives were 2.0-9.1 days. Based on the species sensitivity distribution (SSD) model, the potential affected fraction (PAF) of atrazine in soil samples ranges from 0.01 to 65.8%. Atrazine residues in 43.1% soil samples were higher than 0.11 mg/kg, which was the hazardous concentration for 5% of species (HC5) of atrazine in soil. These results suggested that the ecological risks of atrazine in apples, grapes, and tea garden soil would exhibit a high risk on environmental species even under the same GAP conditions. This study could provide guidance for comprehensive risk assessment of atrazine properly used in apple, grape, and tea gardens.

Chronic ciprofloxacin and atrazine co-exposure aggravates locomotor and exploratory deficits in non-target detritivore speckled cockroach (Nauphoeta cinerea).

The global detection of ciprofloxacin and atrazine in soil is linked to intensive anthropogenic activities in agriculture and inadvertent discharge of industrial wastes to the environment. Nauphoeta cinerea is a terrestrial insect with cosmopolitan distribution and great environmental function. The current study probed the neurobehavioral and cellular responses of N. cinerea singly and jointly exposed to atrazine (1.0 and 0.5μgg-1 feed) and ciprofloxacin (0.5 and 0.25μgg-1 feed) for 63days. Results demonstrated that the reductions in the body rotation, maximum speed, turn angle, path efficiency, distance traveled, episodes, and time of mobility induced by atrazine or ciprofloxacin per se was exacerbated in the co-exposure group. The altered exploratory and locomotor in insects singly and jointly exposed to ciprofloxacin and atrazine were verified by track plots and heat maps. Furthermore, we observed a decrease in acetylcholinesterase and anti-oxidative enzyme activities with concomitant elevation in the levels of lipid peroxidation, nitric oxide, and reactive oxygen and nitrogen species were significantly intensified in the midgut, hemolymph, and head of insects co-exposed to ciprofloxacin and atrazine. In conclusion, exposure to binary mixtures of ciprofloxacin and atrazine elicited greater locomotor and exploratory deficits than upon exposure to the individual compound by inhibiting acetylcholinesterase activity and induction of oxido-inflammatory stress responses in the insects. N. cinerea may be a usable model insect for checking contaminants of ecological risks.

Ultratrace analysis of atrazine in soil using Ice Concentration Linked with Extractive Stirrer and High Performance Liquid Chromatography—Tandem Mass Spectrometry

Atrazine is a widely-used pesticide with a relatively long half-life in the environment. This leads to persistent soil contamination with the potential of migration to ground and surface waters. Analysis of atrazine in soil is difficult due to the inherent complexity of soil as a sample matrix. Moreover, the moderate hydrophobicity of atrazine makes it difficult to extract into typical sorbent phases during sample preparation. Therefore, a method for the ultratrace determination of atrazine in soil using Ice Concentration Linked with Extractive Stirrer (ICECLES) and high performance liquid chromatography—tandem mass spectrometry (HPLC-MS/MS) was developed to address these issues. For the method, soil samples (10 g) were initially extracted with methanol:water (8:2, v:v), followed by solvent exchange to 100% water. The samples then underwent ICECLES with back-extraction into 100% methanol prior to HPLC-MS/MS analysis. The ICECLES-HPLC-MS/MS method produced a wide linear range of 10 to 1000 ng/kg, featured excellent limits of quantification and detection of 10 and 5 ng/kg, respectively, and good accuracy (100 ± 12%) and precision (≤9.6% relative standard deviation). This method was tested on field soil samples and provided ultratrace detection of atrazine. With this method, previously unachievable low parts per trillion (ppt) detection of atrazine in soil is now possible.

Effects of tall fescue biochar on the adsorption and desorption of atrazine in different types of soil.

The excessive application of atrazine in agriculture has resulted in serious environmental contamination. The addition of biochar could reduce the bioavailability and mobility of atrazine in soil through adsorption-desorption processes. In this study, tall fescue biochar was prepared at 500 °C, and its effect on the adsorption-desorption behavior of atrazine in red soil, brown soil, and black soil was investigated. The tall fescue biochar with the pH value of 9.64 had a developed porous structure and large specific area that contained abundant surface functional groups. The element composition of the tall fescue biochar was C (50.46%), O (15.01%), N (4.54%), H (2.56%), and S (1.47%). The adsorption process of atrazine in the three soil types with and without biochar addition was divided into a fast stage, slow stage, and equilibrium stage. A pseudo second-order kinetic model was suitable for fitting the adsorption process of atrazine, and the determination coefficient (R2) ranged from 0.985 to 0.999. The adsorption-desorption processes of atrazine were described accurately by the Freundlich model (R2 of 0.967-0.999). The adsorption capacity of the three soil types for atrazine increased significantly with the addition of biochar, whereby the equilibrium adsorption amount increased from an initial range of 3.968 to 5.902 μg g-1 to a final range of 21.397 to 21.968 μg g-1. The desorption of atrazine was also inhibited as the hysteresis coefficient (HI) increased from an initial range of 0.451 to 0.586 to a final range of 0.916 to 0.941. The adsorption capacity of the red soil improved more than did the brown soil or black soil. Moreover, spontaneous adsorption of atrazine by the biochar-soil system occurred more easily at 35 °C than at 15 °C and 25 °C. Overall, tall fescue biochar was a prospective soil amendment material.

Physiochemical assessment of environmental behaviors of herbicide atrazine in soils associated with its degradation and bioavailability to weeds

Atrazine residue in soil is one of the serious environmental problems and continues to risk ecosystem and human health. To address the environmental behaviors and dissipation of atrazine and better manage the application of atrazine in reality, we comprehensively investigated the adsorption and desorption, migration ability, and vanishing of atrazine in three distinct soils in China including Jiangxi (JX, pH 5.45, TOC 0.54%), Nanjing (NJ, pH 6.15, TOC 2.13%), and Yancheng (YC, pH 8.60, TOC 0.58%) soils. The atrazine adsorptive capacity to the soils was arranged in the order of NJ > YC > JX. The leaching assay with profiles of the soils showed strong migration, suggesting it had a high bioavailability to weeds and potential for underground water contamination. We further investigated the effects of environmental factors such as soil moisture, microbial activity and photolysis on atrazine degradation and showed that the degradation of atrazine in the soil mainly underwent the abiotic process, most likely through hydrolysis and photolysis-mediated mechanisms, and to less extend through soil microbial catabolism. Using HRLC-Q-TOF-MS/MS and by comparing the measured and theoretical m/z values and fragmentation data, ten metabolites comprising eight degraded products and two conjugates were characterized. Atrazine existing in the soils and sprayed coordinately blocked the growth of three common weeds, which prompted us to use the minimal atrazine in practice to control the waste of the pesticide and its impact on the environment. Overall, our work provided an insight into the mechanisms for the degradation of atrazine residues in the soils and contributed to the environmental risk assessment of the pesticide and management in its application control in the crop rotation and safe production.

Degradation of Atrazine, Simazine and Ametryn in an arable soil using thermal-activated persulfate oxidation process: Optimization, kinetics, and degradation pathway

This study examined the feasibility of applying thermal-activated persulfate (PS) oxidation for remediation of soil co-contaminated with s-triazine herbicides including Atrazine (ATZ), Simazine (SIM) and Ametryn (AME). Homogeneous activation using heating method (50 °C) was selected. Results showed that thermal-activated PS oxidation process may successfully degrade ATZ in soil and degradation efficiency was increased along the arising activation temperature. Higher PS dosages and depressed initial pH were beneficial for degradation while increasing initial ATZ concentration may hamper the degradation. The oxidation process may lead to changes of surface functional groups on soil. The presence of Cl−, HCO3− and H2PO4− at both of low and high concentrations may inhibit the degradation of ATZ. Soil depths may apparently influence the ATZ degradation which followed 0−10 < 10−30 < 30−60 cm mainly depending on the soil organic matter (SOM) contents. Thermal-activated PS may effectively degrade ATZ, SIM and AME under co-contaminated condition and the more favorable of ethyl group towards SO4− than isopropyl and methylation groups was detected. Both of SO4− and HO were identified to be responsible for degradation. Finally, degradation intermediates of ATZ, SIM and AME were identified by LC-Q-TOF-MS and detailed transformation pathways for three pesticides were proposed, respectively.