新《生活饮用水卫生标准》GB5749-项目解读：莠去津

resistant to degradation. 2-Chloro-4- ethyl-amino-6-amino-s-triazine, 2-chloro-4-amino-6-isopropylamino-s-triazine, 2-hydroxy-4-ethylamino-6-isopropyl-amino-s-triazine and 2-hydroxy-4- ethylamino-6-amino-s-triazine have been identified as microbial transformation products of atrazine. Chemical degradation of atrazine may be more important environmentally than biodegradation. Atrazine may hydrolyze fairly rapidly in either acidic or basic environments, yet is fairly resistent to hydrolysis at neutral pHs. Furthermore the rate of hydrolysis was found to drastically increase upon small additions of humic materials, indicating atrazine hydrolysis could be catalyzed. For example, the half-life of atrazine at 25 deg C and pH of 4 was 244 days without an additive and 1.73 days with the presence of 2% humic acid. At 25 deg C, a 5 mg/l solution of fulvic acid (naturally occurs in soils and most surface waters) resulted in half-lives of 34.8, 174, 398 and 742 days at pHs of 2.9, 4.5, 6.0 and 7.0, respectively. Hydrolysis of atrazine followed first order kinetics producing hydroxyatrazine as the transformation product. Photolysis of atrazine did not occur in alcohols and water at wavelengths > 300 nm. However, at wavelengths greater than or equal to 290 nm, the photolysis half-life of atrazine at a concn of 10 mg/l in aqueous solution at 15 deg C was 25 hr as compared to a half-life of 4.9 hr for identical conditions with an acetone sensitizer added at a concn of 1 ml/100 ml. Atrazine is expected to maintain a very high to medium mobility class in soils and should not strongly absorb to sediments. Atrazine is not expected to bioconcentrate or volatilize. However if released to the atmosphere, vapor phase reactions with photochemically produced hydroxyl radicals in the atmosphere may be important (estimated half-life of about 2.6 hr). The most probable exposure would be occupational exposure, which may occur through dermal contact or inhalation at places where atrazine is produced or used as a herbicide. Environmental Fate IN LAB MODEL ECOSYSTEM STUDY, WITH (14)C RING-LABELED ATRAZINE THE ENVIRONMENTAL DEGRADATION PRODUCTS WERE 2-AMINO-4-CHLORO-6-ISOPROPYLAMINO-S-TRIAZINE & 2-AMINO-4-CHLORO -6-ETHYLAMINO-S-TRIAZINE. THERE WAS ONLY A SLIGHT DEGREE OF FOOD-CHAIN TRANSFER OF ATRAZINE (ECOLOGICAL MAGNIFICATION 11 TIMES IN FISH) OR ANY OF ITS DEGRADATION PRODUCTS. TERRESTRIAL FATE: The s-triazine ring of atrazine is fairly resistant to degradation. For
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