Atrazine-degrading

Chan K-W, W Chu (2006) Model applications and intermediates quantification of atrazine degradation hy UV-enhanced Fenton process. J Agric Food Chem 54 1804-1813. 

A number of substituted triazines are used as herbicides, and their biodegradation has been discussed in Chapter 10, Part 1. Treatment of soil contaminated with atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-l,3,5-triazine) illustrated a number of significant features. Although the soil that was used had the potential for degradation, a laboratory experiment with Pseudomonas sp. strain ADP that had an established potential for atrazine degradation revealed important limitations. There was a substantial decline in the numbers of Pseudomonas sp. strain ADP and only limited mineralization. Supplementation with citrate or succinate increased the survival of the strain, and successful mineralization was dependent on the preservation of a carbon/nitrogen ratio >10 (Silva et al. 2004). The last would apply generally to substrates with a low C/N ratio such as triazines. 

In addition to SOM, clay minerals are another important component that may influence contaminant-soil interactions. Expandable 2 1 type clays are usually more reactive than other clay minerals. Park et al. (2003) used a K-saturated montmorillonite as a sorbent to evaluate the availability of sorbed atrazine to three atrazine-degrading bacteria. K-saturated montmorillonite has a high atrazine sorption capacity with a Freundlich sorption... 

Sorption of atrazine to four species of marine fungi. Bull. Environ. Contam. Toxicol. 29 101-106. Schocken, M.J. and M.K. Speedie. 1984. Physiological aspects of atrazine degradation by higher marine fungi. Arch. Environ. Contam. Toxicol. 13 707-714. 

Wolf, D.C. and R.L. Jackson. 1982. Atrazine Degradation, Sorption and Bioconcentration in Water Systems. Arkansas Water Resour. Res. Cen. Publ. 87. 40 pp. 

Chemical/Physical. The hydrolysis half-lives of atrazine in O.lM-HCl, buffer at pH 5.0, and O.lM-NaOH solutions at 20 °C were 9.5, 86, and 5.0 d, respectively. Atrazine degraded to 2-chloro-4-amino-6-isopropylamino-5-triazine (Burkhard and Guth, 1981). 

Pang et al. (2005) assumed that atrazine degradation follows a first-order decay law. 

Fig. 16.42 Atrazine degradation in sterilized aquifer material (Al, Bl, Cl) and in natural (unamended) aquifer material (A2, B2, C2) for reactors under stagnant (15°C), stagnant (25°C), and recirculating (15°C) conditions. Data points are the mean of three replications. The least significant difference between these treatments at the p < 0.05 level is 0.075. Figures are identified as (A) Topeka, (B) Ashland, and (C) Hutchinson aquifers. (Schwab et al. 2006)...

Balmer, M.E. Sulzberger, B. Atrazine degradation in irradiated iron/oxalate systems Effect of pH and oxalate. Environ. Sci. Technol. 1999, 33, 2418. 

Of the 44 pesticides and three degradates analyzed for in surface waters of the Lake Erie Basin, 30 were detected at least once [75]. Atrazine was detected in every water sample, including samples from an area with less than 10% row crops (e.g., corn). The atrazine degradate deethylatrazine and the herbicide metolachlor were detected in 99% of the samples (Fig. 11). Eight of the 47 pesticides and degradates were detected in at least 50% of the water samples. All eight of these are herbicides used on row crops, except for prometon, which is used primarily in urban areas. Diazinon and chlorpyrifos were the most frequently detected insecticides, detected in 43% and 22% of the water samples, respectively. The most heavily applied agricultural pesticide not de-... 

Lerch, R. and W. Donald (1994). Analysis of hydroxylated atrazine degradation products in water using sohd-phase extraction and high-performance hquid chromatography. J. Agric. Food Chem., 42 922-927. 

Stolpe, N.B. and P.J. Shea (1995). Alachlor and atrazine degradation in a Nebraska soil and underlying sediments. Soil Sci., 160 359-370. 

Nearly identical atzA, atzB, and atzC genes have been found in five phylogenetically and geographically distinct atrazine-degrading bacteria (de Souza et al., 1998b). 

Genes encoding atrazine degradation activity from Rhodococcus strains have also been reported by Nagy et al. (1995a) and by Shao and Behki (1996). In Rhodococcus strain TE1, an atrA, gene-mediating A-dealkylation of atrazine has been cloned (Shao and Behki, 1995). 

Serial dilutions (10—4 to 10 7) of Pseudomonas strain ADP were added to the surface of a petri dish containing minimal growth medium supplemented with 700-ppm atrazine. Plates were incubated at 35°C for 48 h. Colonies surrounded by clearing-zone show atrazine degradation. 

Figure 22.3 TMn layer chromatograph of (U-ring 14C) atrazine degradation products of pMDl and pMD4.a aThe silica gel plate was developed in chloroform methanohformic acid water (74 20 4 2 v/v). Metabolites were visualized by phosphor imaging.

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