Atrazine Residues In Soil Research Articles

Characteristics of an atrazine degrading bacterium and the construction of a microbial agent for effective atrazine degradation

AbstractA bacterial strain, YQJ‐6, capable of highly degrading atrazine was isolated from soil. Strain YQJ‐6 was identified as Bacillus atrophaeus based on 16S rRNA and the analysis of morphology as well as physiological and biochemical characteristics. The optimal pH value and temperature for strain YQJ‐6 to grow and degrade atrazine were 7.0–7.5 and 30–40°C, respectively. The degradation rate of atrazine (50 mg/L) by strain YQJ‐6 reached approximately 99.2% in 7 days. Strain YQJ‐6 also had a high tolerance to atrazine and could tolerate at least 1000 mg/L atrazine. In addition, strain YQJ‐6 was successfully made into a microbial agent that is easy to commercialize and can be used to treat atrazine residues in soil. The microbial agent containing the strain YQJ‐6 achieved good experimental results. It is believed that strain YQJ‐6 can be used to control atrazine pollution.

Study on the Isolation of Two Atrazine-Degrading Bacteria and the Development of a Microbial Agent.

Two bacteria capable of efficiently degrading atrazine were isolated from soil, and named ATLJ-5 and ATLJ-11. ATLJ-5 and ATLJ-11 were identified as Bacillus licheniformis and Bacillus megaterium, respectively. The degradation efficiency of atrazine (50 mg/L) by strain ATLJ-5 can reach about 98.6% after 7 days, and strain ATLJ-11 can reach 99.6% under the same conditions. The degradation of atrazine is faster when two strains are used in combination. Adding the proper amount of fresh soil during the degradation of atrazine by these two strains can also increase the degradation efficiency. The strains ATLJ-5 and ATLJ-11 have high tolerance to atrazine, and can tolerate at least 1000 mg/L of atrazine. In addition, the strains ATLJ-5 and ATLJ-11 have been successfully made into a microbial agent that can be used to treat atrazine residues in soil. The degradation efficiency of atrazine (50 mg/kg) could reach 99.0% by this microbial agent after 7 days. These results suggest that the strains ATLJ-5 and ATLJ-11 can be used for the treatment of atrazine pollution.

Carryover of tembotrione and atrazine in sugar beet

A field experiment was performed to determine the effects of tembotrione and atrazine residues in soil on sugar beet eight months after herbicide application. The treatments included sugar beet cultivation with tembotrione-contaminated soil (50.4 g a.i. ha-1), tembotrione (100.8 g a.i. ha-1), tembotrione and atrazine (50.4 g a.i. ha-1 + 2 L a.i. ha-1), tembotrione and atrazine (100.8 g a.i. ha-1 + 2 L a.i. ha-1), atrazine (2 L a.i. ha-1) and soil without herbicide application. In general, in comparison to the control, when sugar beets were grown following any of the herbicide treatments, the crop dry biomass was reduced. However, only treatments sprayed with a high rate of tembotrione significantly reduced sugar beet yield.

Use of Sunflower and Soybean as Bioindicators to Detect Atrazine Residues in Soils

ABSTRACT: Atrazine is selective for maize, sugarcane and sorghum and may interfere with successor crops such as sunflower and soybean. Despite this problem, there are few studies about the residual effect of this herbicide in these crops. Thus, the objective of the research was to evaluate the residual effect of atrazine through bioavailability of the herbicide in sandy and clayey soils, using soybean and sunflower as bioindicators. The design was completely randomized with four replications and a 2 × 7 + 1 factorial scheme, that is, two doses (2,000 and 2,500 g ha-1), seven application times (0, 15, 30, 45, 60, 75 and 90 days between application (DBA) of herbicide and bioindicator sowing) and one control without application. Dry mass and chlorophyll content of the bioindicators were evaluated at 20 days after sowing. The accumulation of dry mass of the bioindicators in the two types of soil was reduced at 90 DBA. The chlorophyll content at 0 DBA was zero for soybean and sunflower, due to the reduction of dry mass by approximately 100%. It was concluded that the residual effect of atrazine at a dose of 2,500 g ha-1 was higher in clayey soils due to the low bioavailability of the product in the soil solution. Therefore, it is recommended to sow sunflower and soybean in both soils after 90 DBA, because atrazine interferes with the chlorophyll content and percentage of dry mass reduction.

Transfer of Atrazine Degradation Capability To Mineralize Aged 14C-Labeled Atrazine Residues in Soils

The degradation of environmentally long-term aged (22 years) ¹⁴C-labeled atrazine residues in soil stimulated by inoculation with atrazine-adapted soil from Belgium, the United States (U.S.), and Brazil at two different moisture regimes (50% WHCmax/slurried conditions) was evaluated. Inoculation of the soil containing the aged ¹⁴C-labeled atrazine residues with 5, 50, and 100% (w/w) Belgian, U.S., or Brazilian atrazine-adapted soil increased ¹⁴C-atrazine residue mineralization by a factor of 3.1-13.9, depending upon the amount of atrazine-adapted soil inocula and the moisture conditions. Aged ¹⁴C-atrazine residue mineralization varied between 2 and 8% for Belgian and between 1 and 2% for U.S. and Brazilian soil inoculum at 50% WHCmax but was increased under slurried conditions, accounting for 8-10% (Belgian soil), 2-7% (Brazilian soil), and 3% (American soil). The results show that an increased degradation of long-term aged ¹⁴C-labeled atrazine residues is possible by the transfer of atrazine-adapted soil microflora from different soils and regions to non-adapted soil.

Spatial Distribution and Characterization of Long-Term Aged14C-Labeled Atrazine Residues in Soil

The long-term behavior of the herbicide atrazine and its metabolites in the environment is of continued interest in terms of risk assessment and soil quality monitoring. Aqueous desorption, detection, and quantification of atrazine and its metabolites from an agriculturally used soil were performed 22 years after the last atrazine application. A lysimeter soil containing long-term aged atrazine for >20 years was subdivided into 10 and 5 cm layers (at the lysimeter bottom: soil 0-50 and 50-55 cm; fine gravel 55-60 cm depth, implemented for drainage purposes) to identify the qualitative and quantitative differences of aged (14)C-labeled atrazine residues depending on the soil profile and chemico-physical conditions of the individual soil layers. Deionized water was used for nonexhaustive cold water shaking extraction of the soil. With increasing soil depth, the amount of previously applied (14)C activity decreased significantly from 8.8% to 0.7% at 55-60 cm depth whereas the percentage of desorbed (14)C residues in each soil layer increased from 2% to 6% of the total (14)C activity in the sample. The only metabolite detectable by means of LC-MS/MS was 2-hydroxyatrazine while most of the residual (14)C activity was bound to the soil and was not desorbed. The amount of desorbed 2-hydroxyatrazine decreased with increasing soil depth from 21% to 10% of the total desorbed (14)C residue fraction. The amount of (14)C residues in the soil layers correlated well with the carbon content in the soil and in the aqueous soil extracts ( p value = 0.99 and 0.97, respectively), which may provide evidence of the binding behavior of the aged atrazine residues on soil carbon. The lowest coarse layer (55-60 cm) showed increased residual (14)C activity leading to the assumption that most (14)C residues were leached from the soil column over time.

Risk Assessment of Atrazine polluted Farmland and Drinking Water: A Case Study

Atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino]-striazine) is a herbicide widely used for the protection of corn, sugarcane, grain sorghum, tea, and fruit crops. Since the introduction of atrazine to China in the early 1980s, its consumption in China has been increasing by 20% each year (Shu, 2000). Atrazine has been detected in the surface water and groundwater of several European Union countries (Siebers, 1994). The maximum contaminant level of 0.1 lg/L in drinking water has been detected in European Union countries, and 3 lg/L has been detected in the United States and China (Wust et al., 1992). At a low soil pH, protonized atrazine becomes more hydrophilic, with the result that this compound moves downward to groundwater through water infiltration of soil. Furthermore, the higher the organic matter and clay contained in soil, the stronger the atrazine bond to the soil solid phase. An investigation conducted in Nebraska, USA, showed that 0.07% of the total atrazine applied to a sandy loam infiltrated down to 1.5 m below the surface (Capriel et al., 1986). In the case of paddy fields, frequent irrigation facilitates atrazine leaching in soils. It has been proposed that leaching and degradation are the two main pathways of atrazine dissipation in paddy fields, whereas the contribution of surface runoff is less important than these two pathways (Alissara and Thomas, 2001). In late May 1997, a large-scale pollution incident occurred in the rice-growing area of Changtu County, Liaoning Province. During this incident, more than 2,800 ha of rice fields were heavily contaminated by atrazine during a short period of irrigation by atrazine-polluted waters from two rivers across the rice fields: the Tiaozi and Zhaosutai Rivers. An official investigation was conducted subsequently to trace the sources of atrazine in the rivers. It was found that an accidental leakage occurring in Siping City, Jilin Province, located on the upper reaches of the two rivers, resulted in a substantially higher concentration of atrazine upstream in the rivers. Rice seeds died in many of the contaminated fields, leading to a direct loss of about US$ 4.4 million (National Pharmacy Water Pollution Control Center [NPHC], 2005). A 6-month monitoring study was conducted immediately after the accident. According to the report issued by the Pesticides Safety Evaluation Center (PSEC) in July 1997, atrazine concentrations measured around Bamiancheng, one of the major rice-growing regions in Changtu County, ranged from 0.06 to 0.29 mg/L in the Tiaozi River, from 0.23 to 0.36 mg/kg in soils, and from 1.07 to 2.26 mg/kg in young rice shoots. Atrazine concentrations around Baoli, another rice-growing region of the County, was 0.03 to 0.06 mg/L in the Zhaosutai River, up to 0.08 mg/kg in soils, and 0.28 mg/kg in young rice shoots. Given the unusually high concentration and persistence of atrazine in environments, a concern is raised. How long will this accident affect the local ecosystem and environment? The current study aimed to determine atrazine residues in soils, rice grains, and drinking water in the contaminated area from November 1997 to October 2001 after the Q. Li (&) College of Environmental Science and Engineering, Dalian Maritime University, 1, Linghai Road, Dalian, Liaoning 116026, China e-mail: drlqb@yahoo.com.cn

The effect of Atpolan 80 EC on atrazine residues in the soil

The effect of Atpolan 80 EC on atrazine residues in the soil The persistence of atrazine residues in soils may have an effect on the contamination of the ground water or surface water. Besides the active ingredients, pesticide formulations contain many other compounds called adjuvants. One of them is the Atpolan 80 EC which belongs to the group of oil mineral adjuvants used as tank-mix. The utilization of a fraction of paraffin oil 1113 is one of the examples of utilising waste as the component of Atpolan 80 EC in agriculture. When the Atpolan concentration comprised 1.25% (v/v), the atrazine degradation rate decreased in the sandy loam and muck soil. The half-life of atrazine increased over a period of 40 or 57 days, depending on the type of the soil. The least significant effect was caused by Atpolan concentration at 0.25 and 0.75%. This result points at the capability of limiting atrazine run-off and leaching down the soil profile. Each ingredient of the pesticide, besides having the overall ability to distribute between different phases, also demonstrates some single compound behaviour. This paper shows our current understanding of the factors that influence the adjuvant performance and their potentially complex interactions with the pesticide.

Solvent extraction characterization of bioavailability of atrazine residues in soils.

Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. The objective of this study was to correlate atrazine residue bioavailability in aged soils, as determined by solvent extraction methods, to atrazine mineralization by an atrazine-degrading bacterium. Webster clay loam and Zimmerman fine sand soils were treated with UL-ring-labeled [14C]atrazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either not extracted, extracted with 0.01 M CaCl2, or extracted with 0.01 M CaCl2/aqueous methanol. Soils were then inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing the atrazine ring. This allowed for the evaluation of the bioavailability of aged atrazine residues without the contribution of atrazine desorption from soil. Results of these studies indicated that the amounts of atrazine residues in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were correlated to amounts of atrazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol extractable atrazine in aged soils may be used to estimate bioavailable residues, and this technique may be useful to determine the bioavailability of other compounds in soils, especially other triazine herbicides.

Long-Term Monitoring of Atrazine Contamination in Soil by ELISA

An enzyme-linked immunoassay (ELISA) was used for screening atrazine residues in soil. Samples were annually collected in Southern Germany between 1993 and 1998. An average of 419.5 samples was analyzed per year amounting to 2517 samples. The fraction of positive samples defined by atrazine concentrations >100 microg/kg soil decreased successively from 8% (corresponding to 33 samples) in 1993 to 0.6% (corresponding to 2 samples) in 1998. All positive samples and a selection of negative samples were subsequently validated by HPLC. Comparison of ELISA and HPLC data yielded correlation coefficient values of r = 0.958-0.981 (n = 18-47), except for 1995 when only a correlation of r = 0.864 (n = 18) was obtained. Four samples were overestimated and another 4 were underestimated with respect to the atrazine threshold value of 100 microg/kg soil as revealed by HPLC validation. Thus, 99.68% of 2,517 analyzed samples were correctly evaluated. The precision and reproducibility of the ELISA were adequate for a prescreening tool. The low cost per sample and the high sample throughput are not yet achievable by conventional analytical methods. The described combination of ELISA and HPLC has the potential to take advantage of both methods and to restrict determination errors to a minimum.

Wheat Cultivar Tolerance to Atrazine

Winter wheat (Triticum aestivum L.) in the Texas High Plains often follows a crop or fallow period where atrazine was used for weed control. A study was conducted in 1991–1992 and repeated in 1993–1994 to determine if differences exist among commonly grown winter wheat cultivars in their tolerance to atrazine. Eighteen hard red winter wheat cultivars common to the region were planted on 13 Nov. 1991, and 26 Oct. 1993, in plots treated with 0, 0.25, 0.5, 0.75, and 1.0 lb a.i. /acre atrazine. Variation in atrazine tolerance was observed among cultivars and years, but cultivar differences in atrazine tolerance were identified. Cultivars that exhibited tolerance to atrazine were ‘Triumph’, ‘Scout’, ‘Siouxland 89’, ‘TAM 107’, and ‘Quantum 588A’. Most susceptible cultivars were ‘TAM 109’, ‘TAM 200’, ‘TAM 201’, and ‘TAM 202’. These data suggest cultivars are available to minimize yield loss for planting in fields where atrazine residues in soil are suspected. Alternatively, where atrazine is applied to wheat stubble after harvest, cultivars that are susceptible to atrazine could be planted to aid in control of volunteer wheat. Research Question Atrazine is commonly used to control weeds in sorghum, corn, and during fallow periods in the Texas High Plains. When wheat is planted in soil previously treated with atrazine, the potential for crop injury exists, especially in soils that have a high pH and low organic matter content. Little research has been done to determine if hard red winter wheat cultivars differ in their tolerance to atrazine under field conditions. The objectives of this study were to determine if commonly grown hard red winter wheat cultivars differ in their tolerance to atrazine and to develop a database for guidance to producers faced with atrazine residues in fields to be planted to wheat, or who desire to plant cultivars susceptible to atrazine. Literature Summary Studies have shown that wheat cultivars differ in tolerance to metribuzin and cyanazine under field conditions. Because of chemical similarities of atrazine to these herbicides, it seems likely that differences in cultivar tolerance to atrazine may exist. A greenhouse study in Arkansas revealed differences in wheat cultivar seedling response to atrazine. Study Description Field studies were conducted during 2-yr cycles near Bushland, TX during 1991–1992 and 1993–1994. Soil was a Pullman clay loam and is typical of the soils found in the southern Great Plains. Soil organic matter at the site was 1.2% and pH was 7.5. The experimental area had been neither cropped nor treated with herbicides during the previous 2 yr. In order to simulate residual carryover, atrazine was applied in strips (blocks) prior to wheat planting at 0, 0.25, 0.5, 0.75, and 1.0 lb a.i/acre. Eighteen hard red winter wheat cultivars (Table 1) common to the region were planted across the atrazine blocks in three replications in a split-plot arrangement. Differences in wheat cultivar tolerance to atrazine were determined by collecting data for percent stand and grain yield reduction. Applied Questions Do differences exist between winter wheat cultivars in their tolerance to atrazine? In both years tested there were clearly differences in wheat cultivar tolerance to atrazine. Which cultivars consistently showed the most tolerance and susceptibility to atrazine? Cultivars that exhibited tolerance to atrazine in both years were Triumph, Scout, Siouxland 89, followed by TAM 107 and Quantum 588A (Table 1). Most susceptible cultivars in both years were TAM 109, TAM 200, TAM 201, and TAM 202. Recommendation How can producers utilize wheat cultivar tolerance differences to atrazine? Producers who desire to plant wheat in fields that may contain atrazine residue can minimize atrazine injury by planting tolerant cultivars while avoiding those that are most susceptible. If a cropping system involves the use of atrazine after wheat harvest, it may be desirable to plant one of the susceptible TAM cultivars in order to improve control of volunteer wheat. Table 1. Quantitative summary of wheat cultivar tolerance to atrazine from studies conducted during the 1991–1992 and 1993–1994 growing seasons at Bushland, TX. Tolerant Intermediate Susceptible Siouxland 89 Karl TAM 202 Triumph Mesa TAM 200 Scout Thunderbird TAM 201 Quantum 588A 2158 TAM 109 TAM 107 Abilene Hawk Bronco 2157 Chisholm

Mixed-Mode Sorption of Hydroxylated Atrazine Degradation Products to Soil: A Mechanism for Bound Residue

This study tested the hypothesis that sorption of hydroxylated atrazine degradation products (HADPs: hydroxyatrazine, HA; deethylhydroxyatrazine, DEHA; and deisopropylhydroxyatrazine, DIHA) to soils occurs by mixed-mode binding resulting from two simultaneous mechanisms: (1) cation exchange and (2) hydrophobic interaction. The objective was to use liquid chromatography and soil extraction experi ments to show that mixed-mode binding is the mechanism controlling HADP sorption to soils and is also a mechanism for bound residue. Overall, HADP binding to solid-phase extraction (SPE) sorbents occurred in the order: cation exchange ≫ octadecyl (C18) ≫ cyanopropyl. Binding to cation exchange SPE and to a high-performance liquid chromatography octyl (C8) column showed evidence for mixed-mode binding. Comparison of soil extracted by 0.5 M KH2PO4, pH 7.5, or 25% aqueous CH3CN showed that, for HA and DIHA, cation exchange was a more important binding mechanism to soils than hydrophobic interaction. Based on differences between several extractants, the extent of HADP mixed-mode binding to soil occurred in the following order: HA > DIHA > DEHA. Mixed-mode extraction recovered 42.8% of bound atrazine residues from aged soil, and 88% of this fraction was identified as HADPs. Thus, a significant portion of bound atrazine residues in soils is sorbed by the mixed-mode binding mechanisms.

Influence of plant carbon on the mineralisation of atrazine residues in soils

The persistence of the s-triazine herbicides such as atrazine has led to increasing concern about environmental contamination by these compounds. A laboratory incubation experiment was carried out to determine the effects of plant residues on the mineralisation of atrazine residues in an agricultural soil with no recent history of atrazine application. The experiment further aimed to identify the importance of different fractions (water soluble and insoluble) of plant residues to the dynamics and extent of hydroxy-atrazine mineralisation. Hydroxy-atrazine mineralisation was initially (0 – 2 days) enhanced by the addition of water-insoluble plant (pea) fractions and inhibited by addition of water-soluble plant fractions. However, by the end of the incubation (10 days), only addition of unfractionated shoot material caused overall enhancement of hydroxy-atrazine degradation. Little or no lag in mineralisation in a soil which had not been exposed to the atrazine for 15 years demonstrated long-term maintenance of degradative capability.

Atrazine Residues in Soil Two Years After the Atrazine Ban - A Comparison of Enzyme Immunoassay with HPLC

Abstract Two years after the atrazine ban in Germany, 417 soil samples from corn fields were screened for atrazine. The analyses were carried out by an enzyme immunoassay (EIA) using polyclonal antibodies from sheep. Thirty five samples contained more than 100 μg atrazine per kg of soil and were considered positive, indicating this year application. The concentrations of all positive samples and several negative samples were validated by HPLC. A correlation of r = 0.96 was obtained. When two different extraction methods using water or acetone were compared, no difference in atrazine yields were found with the EIA. The EIA proves to be a useful screening method, as long as positive samples can be validated by other methods such as HPLC or GC. *Dedicated to Prof. Dr. Dr. h. c. H. Ziegler, TU Munchen, on the occasion of his 70th birthday.

Determination of Weathered Atrazine Residues in Soil by Enzyme Immunoassay and HPLC: An Evaluation Study.

Abstract This study was conducted to evaluate a specific enzyme immunoassay (EIA) for the quantification of weathered atrazine residues in soils at concentration levels below 50 μg/kg. Samples of widely differing soil types were analysed with EIA before clean-up and HPLC after clean-up of the soil extracts. On average EIA slightly overestimated the atrazine concentration compared to HPLC by 1.2 μg/kg. The coefficient of determination was r2=0.95. EIA proved to be a valid analytical method and especially effective when many soil samples have to be screened for atrazine residues or illegal atrazine application. In cases where EIA indicates atrazine residues, analysis with HPLC-DAD can follow up, providing detailed information on its metabolites deethyl-, deisopropyl-, and hydroxyatrazine.

Spatial distribution of atrazine residues in soil and shallow groundwater: effect of tillage and rainfall timing

A field study began in 1986 to determine the effects of no-till (NT) and conventional-till (CT) management practices on the movement and leaching characteristics of several commonly used pesticides to shallow groundwater during corn ( Zea mays L.) production. Specifically, the effect of tillage and rainfall timing on the spatial distribution of atrazine in the 0–30 cm soil depth and in shallow groundwater (less than 1 m depth) was evaluated in 1987, 1988, and 1989. These 3 years were selected because nearly the same amount of rain fell, but at different times and intensities, within the period between atrazine application and the first sampling. The average atrazine residues in the top 10 cm of soil of the two CT plots were much higher than the two NT plots in all years, regardless of the rainfall timing. This difference was about 23% in 1987 (first rain occurred 3 days after application), 56% in 1988 (12 h after application), and 63% in 1989 (6 days after application). Atrazine residue levels of 663 and 424 μg l −1 were found in the samples collected, from the wells above the clay layer, 3 days after the first rain event in 1988, in the two NT plots. However, the concentrations decreased to 133 μg l −1 and 105 μg l −1 and 6 μg l −1 and 5 μg l −1 after 14 and 40 days, respectively. These relatively high residue levels in 1988 presumably resulted because the first rain event which contributed 48 mm of rain began 12 h after application and lasted about 2 days. The average residue levels of atrazine in the wells below the clay layer in the NT plots were higher than the CT plots in all 3 years. The semi-variograms for atrazine residues in the 0–30 cm soil depth showed that the residue values were spatially related for the separation distance of less than 16 m. For the well water samples, this distance was estimated to be about 30 m.

Measurement of atrazine residues in soil and groundwater

Measurement of atrazine residues in soil and groundwater

Determination of Atrazine Residues in Electro‐Ultrafiltration Soil Extracts by a Sensitive Enzyme Immunoassay

AbstractA sensitive enzyme immunoassay (EIA) based on polyclonal antibodies from sheep was used to screen for atrazine in electro‐ultrafiltration (EUF) soil extracts without clean‐up. Matrix effects were circumvented by diluting the aqueous EUF extracts. The EUF proved to be a convenient method for the extraction of atrazine residues in soil. The efficiency of EUF appeared to be equivalent to that of organic extraction methods except on weathered residues, which generally resulted in lower yields. Both the combined gas chromatography/automated Soxhlet (GC/Soxtec) and the immunochemical technique EIA/EUF yielded similar data for the 26 soil samples identified as positive (> 0.02 mg/kg) during the first screening of 479 EUF extracts by the EIA.

Modification of atrzine desorption during field incubation experiments

The effect of field aging on atrazine desorption was determined. 14C-ring labelled atrazine was applied to the top of soil columns in field plots. The columns were periodically removed from the field for 16 months after application. The desorption isotherms of [ 14C]atrazine residues were determined on the surface soil using the batch equilibration method with 0.01 M CaCl 2 solution. The distribution of atrazine residues in soil and liquid phases was determined by total 14C analysis and HPLC with a radiactive flow detector to identify the [ 14C]atrazine derivatives. In laboratory experiments, desorption coefficients were dependent on the absorbed atrazine concentrations; low concentrations were retained to a greater extent and were more difficult to desorb than the higher concentrations. For the field aged residues, desorption K f values increased slightly with aging. However, the values were lower than would be expected from the laboratory values if equal adsorbed concentrations are compared. It is not possible, however, to predict the desorption behavior of atrazine in the field samples from the simple adsorption-desorption laboratory studies. It is necessary to take into account the change in the atrazine-soil interactions with aging.

Screening and Monitoring of Herbicides Behaviour in Soils by Enzyme Immunoassays

Abstract A simplified approach to screen cropland for residues of atrazine and its main metabolite deethylated atrazine has been presented. A time-saving and cost-effective screening method has been developed using an aqueous extraction step. The measurement of the extracts was done by immunoassay technique (ELISA). Antibodies against atrazine and deethylated atrazine were used in the study. The overall detection limit of the analysis of atrazine residues in soil is 1 μg kg−1 and 2 μg kg−1 for its deethylated metabolite, respectively. It is shown that this approach yields adequate information to judge the ground-water hazard potential of treated fields.