Atrazine persistence

Brecke, B.J., W.L. Cuney, and D.H. Teem. 1981. Atrazine persistence in a com-soy bean doublecropping system. Agron. Jour. 73 534-537. 

Hammons, R.H. 1977. Atrazine Persistence in a Valentine Loamy Fine Sand Profile. M.S. Thesis. Univ. Nebraska, Lincoln. 48 pp. 

The persistence (half-life) of atrazine in the subsurface is governed by chemically and biologically mediated transformations. Because the solubility of atrazine is relatively high ( 30mg/L) compared to its toxicity level in water (5 Lig/L), atrazine has become a hazard to groundwater quality. Atrazine has been detected in groundwater more than any other crop protection chemical two examples of atrazine persistence-transformation in aquifer environments are discussed next. 

Leavitt, R.A., J.J. Kells, J.R. Bunkelmann, and R.M. Hollingworth (1991). Assessing atrazine persistence in soil following a severe drought. Bull. Environ. Contam. Toxicol., 46 22-29. 

Reinhardt, C.F. and PC. Nel (1993). The influence of soil type, soil water content and temperature on atrazine persistence. South African J. Plant Soil, 10 45 19. 

Initial soil triazine concentration has been shown to affect persistence, with higher rates having slower dissipation (Davidson et al., 1980). In clay loam and sandy loam soils, atrazine persistence in the field was greater for high-rate treatments than for low-rate treatments during the first six months (Gan et al., 1996). On an absolute basis, however, the amount of atrazine dissipated from the high-rate treatment was greater than the low-rate treatment. 

Bowmer, K.H. (1991). Atrazine persistence and toxicity in two irrigated soils of Australia. Aust. J. Soil Res., 29 339-350. 

Rohde, W.A., L.E. Asmussen, E.W. Hauser, M.L. Hester, and H.D. Allison (1981). Atrazine persistence in soil and transport in surface and subsurface runoff from plots in the coastal plain of the southern United States. Agro-Ecosystems, 1 225-238. 

Atrazine One of the most widely used agricultural herbicides. Atrazine persists in ground water and can induce hermaphroditism in frogs. 

Most soil-boimd pesticides are less hkely to volatihze or to leach through the soil. They are also less easily taken up by plants. In terms of environmental fate, bound residues can be significant and may result in the underestimation of chemical half-life. A nine-year outdoor study showed that soil residues contained as high as 50-60% of the initial apphed radioactivity of C-atrazine [38,39], and some transformation products of atrazine persisted for 9 years in outdoor conditions [39]. Most of the boimd residues were the hydroxy analogues of atrazine and their dealkylated products. 

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... 

Ureides (e.g., diuron, linuron) and triazines (e.g., atrazine, simazine, ametryne) all act as inhibitors of photosynthesis and are applied to soil (see Figure 14.1 for structures). They are toxic to seedling weeds, which they can absorb from the soil. Some of them (e.g., simazine) have very low water solubility and, consequently, are persistent and relatively immobile in soil (see Chapter 4, Section 4.3, which also mentions the question of depth selection when these soil-acting herbicides are used for selective weed control). 

The persistence of the N-nitrosamine that may be formed in soil will depend on a host of conditions, such as soil type, organic matter content, clay content, pH, the microflora present in the soil, moisture content and temperature, etc. Superimposed on all these factors will be the chemical nature of the pesticide. The N-nitrosoatrazine ( ) formed in soil from the herbicide atrazine ( ) was shown to be rapidly disappeared (1). Thus, in soil W-nitrosoatrazine was observed after one week, but was absent 4 and 10 weeks later (Table IV). In contrast, N-nitroso-butralin (11 ) persisted much longer than N-nitrosoatrazine (9) under the same conditions (Table V) and was still detectable after 6 months (3). Our studies demonstrated that N-nitrosoglyphosate is persistent in the soil. Fox soil treated with 20 ppm of nitrite nitrogen and 740 ppm glyphosate contained about 7 ppm of N-nitrosoglyphosate even after 140 days (6). 

Park J-H, Feng Y, Ji P, Voice TC, Boyd SA (2003) Assessment of bioavailability of soil-sorbed atrazine. Appl Environ Microbiol 69 3288-3298 Pignatello JP, Sawhney BL, Frink CR (1987) EBD persistence in soil. Science 236 898... 

In terrestrial ecosystems, atrazine effectively inhibits photosynthesis in target weeds and can also affect certain sensitive crop plants. Atrazine metabolites are not as phytotoxic as the parent compound. Degradation is usually rapid, although atrazine can persist in soils for more than one growing season. Soil fauna may be adversely affected shortly after initial atrazine application at recommended levels, but long-term population effects on this group are considered negligible. 

Amor, R.L., A. Kent, P.E. Ridge, and R.M. Binns. 1987. Persistence of atrazine in chemical fallows in the Victorian Wimmera and Mallee. Plant Protect. Quar. 21 38-40. 

Isensee, A.R. 1987. Persistence and movement of atrazine in a salt marsh sediment microecosystem. Bull. 

Yoo, J.Y. and K.R. Solomon. 1981. Persistence of permethrin, atrazine and methoxychlor in a natural lake system. Canad. Tech. Rep. Fish. Aquat. Sci. 1151 164-167. 

Several hundred-pesticide compounds of diverse chemical structures are widely used in the United States and Europe for agricultural and non-agricultural purposes (Fig. 10). Some are substitutes for organochlorines, which were banned due to their toxicity, persistence, and bioaccumulation in environmental matrices. According to a report published by the US-EPA, a total of 500,000 tons of pesticides was used in 1985 [144, 145, 148]. As far as specific pesticides are concerned, worldwide consumption of Malathion and Atrazine in 1980 amounted to 24,000 and 90,000 tons, respectively [149,150]. In the Mediterranean countries, 2100 tons of Malathion (active ingredient) were sprayed during the same period compared to 9700 tons in Asia [150]. 

Schwab AP, Splichal PA, Banks MK (2006) Persistence of atrazine and alachlor in ground water aquifers and soil. Water Air Soil Poll 171 203-235 Schwarzenbach RP, Gschwend PM, Imboden DM (2003) Environmental organic chemistry, 2nd edn. Wiley-Interscience, Hoboken, New Jersey... 

In the field, atrazlne has been found to have a half-life of <1 month, but the half-life is affected by the tillage system (44-46), the agricultural soil ammendments and soil pH (45-48), and soil organic matter (49). In another study, atrazine and hydroxyatrazlne have been found to persist into the following growing season (50). 

---