Atrazin

Figure 5-31. Search for atrazine and daphnia toxicity in the Cennan Environmeiital Information NetworkGEIN portal (excerpt from search, October 21, 2002) http //wu u. geln.de/incfex en.htm ).

For the sample search on aquatic toxicity of atrazine, 1459 results were found. An excerpt on the daphnia acute aquatic toxicity tests (EC50. LC.50) is prc.scnted in Figure 5-33. 

Figure 10.1-12. Reaction network obtained for atrazine by application of the two reaction types shown In Figure 10.3-8,...

Triazines pose rather more of a problem, probably because the carbons are in an effectively oxidized state so that no metaboHc energy is obtained by their metaboHsm. Very few pure cultures of microorganisms are able to degrade triazines such as Atrazine, although some Pseudomonads are able to use the compound as sole source of nitrogen in the presence of citrate or other simple carbon substrates. The initial reactions seem to be the removal of the ethyl or isopropyl substituents on the ring (41), followed by complete mineralization of the triazine ring. 

Triazines. Triazine herbicides are one of several herbicide groups that are heterocycHc nitrogen derivatives. Triazine herbicides include the chloro-, methylthio-, and methoxytriazines. They are used for the selective pre-emergence control and early post-emergence control of seedling grass and broadleaved weeds in cropland (299). In addition, some of the triazines, particularly atrazine, prometon [1610-18-0] and simazine [122-34-9] are used for the nonselective control of vegetation in noncropland (2). Simazine may be used for selective control of aquatic weeds (2). 

H-Dealkylation. This is commonly observed as a primary transformation of pesticides with A/-alkyl substituents, such as atrazine [1912-24-9] (3) (eq. 5), trifluraHn [1582-09-8] (4) (eq. 6) (16), and 3 -ethyl dipropylthiocarbamate [759-94-4] (EPTC) (5) (eq. 7) (18). These reactions are catalyzed by a variety of bacterial strains, including Noeardia, Pseudomonas, Phodococcus, and Streptomyces. 

Hydrodechlorination is a common reaction of chlorinated pesticides such as atrazine (eq. 15), alachlor, and metolachlor (2) (eq. 16). These reactions are catalyzed primarily by transition metals or by soil surfaces (clays or humic substances). 

Of the various inorganic soil constituents, smectites (montmorillonite clays) have the greatest potential for sorption of pesticides on account of their large surface area and abundance in soils. Weak base pesticides, both protonated and neutral species, have been shown to be sorbed as interlayer complexes. Sorption of atrazine on smectites ranges from 0 to 100% of added atrazine, depending on the surface charge density of the smectite (36). 

Observing the amount and variety of pesticides analyzed by GC chromatography we decided to observe 14 of the most represented pesticides Prometryn, Deltamethrin, Fenitrothion, Tebuconazole, Buprofezin, Malathion, Myclobutanyl, Atrazine, Acetochlor, Bifenthrin, Alachlor, Pendimethalin, Dichlonuid and Trifluralin. 

Atrazine, carbofuran, carbaryl, esfenvalerate, imidazole fungicides Industrial chemicals... 

Herbicides Diquat bromide Atrazine Simazine Diiiron... 

K. J. Maeek, K. S. Buxton, S. S. Sauter, S. Gnilka and J. W. Dean, Chronic Toxicity of Atrazine to Selected Aquatic Invertebrates and Pishes, Environmental Researeh Laboratory, US Environmental Proteetion Ageney, Deluth, MN, 1976, EPA 600/3-76-047. 

Atrazine and simazine arose principally as a result of their use in amenity situations but, since their ban for non-agriciiltiiral purposes, concentrations are generally declining. Fiowever, atrazine and simazine still have some agricultural uses (atrazine on maize and simazine on a wide range of crops), so the risk of pollution still exists when these pesticides are applied in either groundwater or surface water drinking water supply catchments. 

Until recently, the NRA has not participated during the approval process in assessing the potential environmental impact of pesticides. However, the NRA does supply monitoring data to MAFF and HSE for pesticide reviews. These occur once a pesticide has been approved for use for a certain length of time, or when further information is needed on an approved pesticide. In supplying these data, the NRA comments on any areas of concern. This contributed to the 1993 ban on the use of atrazine and simazine on non-cropped land. In January 1995 the NRA s National Centre for Toxic and Persistent Substances (TAPS) was made advisor to the DoF, on the potential impact on the aquatic environment of... 

Where both atrazine and simazine are released, the figure in aggregate is 350 grams. 

Miscellaneous compounds such as biopesticides (for example. Bacillus thuringiensis and pherhormones), heterocycles (for example, atrazine), pyrethroids (for example, cypermethrin), and urea derivatives (for example, diuron). 

There are at least 22 chemical families of organic herbicides. Even a cursory treatment of the chemistry of these materials would be extensive. Herbicides of limited toxicity (Treflan, Atrazine) as well as extremely toxic ones (Paraquat. Dinoseb) are in use in many parts of the world. They range from water soluble to insoluble. The detailed chemistry of each should be determined prior to handling. 

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