Simazine water

Herbicides. An array of herbicides are registered for use in aquatic sites, but copper sulfate and diquat dibromide are of additional interest because they also have therapeutic properties (9,10). Copper sulfate has been used to control bacteria, fungi, and certain parasites, including Jchthjophthirius (ich). Diquat dibromide can control columnaris disease, but it also exhibits fungicidal properties (9,10). EPA recentiy proposed to limit the amount of diquat dibromide, endothaH, glyphosate, and simazine that can be present in drinking water therefore, the use of these compounds may be reduced if they cannot be removed from the effluent. 

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. 

Proposed by Water Research Centre, s Proposed by NRA. llAtrazinie and Simazine. 

Figure 13.15 Chromatograms obtained by on-line ti ace enrichment of 50 ml of Ebro river water with and without the addition of different volumes of 10% Na2S03 solution for every 100 ml of sample (a) blank with the addition of 1000 p.1 of sulfite (b) spiked with 4 p.g 1 of the analytes and 1000 p.1 of sulfite (c) spiked with 4 p.g 1 of the analytes and 500 p.1 of sulfite (d) spiked with 4 p.g 1 of the analytes without sulfite. Peak identification is as follows 1, oxamyl 2, methomyl 3, phenol 4, 4-niti ophenol 5, 2,4-dinitrophenol 6, 2-chlorophenol 7, bentazone 8, simazine 9, MCPA 10, atrazine. Reprinted from Journal of Chromatography, A 803, N. Masque et ai, New chemically modified polymeric resin for solid-phase extraction of pesticides and phenolic compounds from water , pp. 147-155, copyright 1998, with permission from Elsevier Science.

Figure 13.19 Chromatograms obtained by on-line SPE-GC-MS(SIM) of (a) 10 ml of tap water spiked with pesticides at levels of 0.1 ng 1 (b) 10 ml of a sample of unspiked tap water. Peak identification foi (a) is as follows 1, molinate 2, a-HCH 3, dimethoate 4, simazine 5, ati azine 6, y-HCH 7, S-HCH 8, heptachloi 9, ametiyn 10, prometiyn 11, fen-itrothion 12, aldrin 13, malatliion 14, endo-heptachlor 15, a-endosulfan 16, teti achlor-vinphos 17, dieldrin. Reprinted from Journal of Chromatography, A 818, E. Pocumll et al., On-line coupling of solid-phase exti action to gas cliromatography with mass specti ometiic detection to determine pesticides in water , pp. 85-93, copyright 1998, with permission from Elsevier Science.

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). 

Supercritical fluid extraction (SFE) is generally used for the extraction of selected analytes from solid sample matrices, but applications have been reported for aqueous samples. In one study, recoveries of 87-100% were obtained for simazine, propazine, and trietazine at the 0.05 ug mL concentration level using methanol-modified CO2 (10%, v/v) to extract the analytes, previously preconcentrated on a C-18 Empore extraction disk. The analysis was performed using LC/UV detection. Freeze-dried water samples were subjected to SFE for atrazine and simazine, and the optimum recoveries were obtained using the mildest conditions studied (50 °C, 20 MPa, and 30 mL of CO2). In some cases when using LEE and LC analysis, co-extracted humic substances created interference for the more polar metabolites when compared with SFE for the preparation of the same water sample. ... 

The effects of water temperature and pesticide concentration on pesticide recoveries were tested by Moye et al The pesticides included alachlor, atrazine, bromacil, chlorothalonil, chloropyrifos, diazinon, endosulfan, simazine and trifluralin. Temperatures of 5,25,45 and 65 °C were tested and concentrations of 0.1,1.0 and 10 pgL were used. Water temperature had a pronounced effect on the recoveries whereas the concentration did not seem to have as great an effect. 

Kicuchi and Saito used carbon Empore disks in combination with SDB-XD Em-pore disks to extract polar (methamidophos, acephate and trichlorfon) and nonpolar pesticides (diazinon, chloroneb and simazine) from water. The water sample (500 mL) was passed through the disk and the disk simultaneously eluted with 30 mL of acetone-ethyl acetate (1 1). The samples were concentrated and analyzed by GLC/MS. 

Pesticides contaminate not only surface water, but also ground water and aquifers. By 1990 in the USSR, 15% of all pesticides used were detected in underground water [29]. Pesticides were detected in 86% of samples of underground water in Ukraine in 1986-87 (including DDT and its metabolites, HCH, dimethoate, phosalone, methyl parathion, malathion, trichlorfon, simazin, atrazine, and prometrin). In actual fact, the number of pesticides was apparently larger, but the laboratory was able to determine the content of only 30 of the 200 pesticides used at that time in Ukraine [29]. In the 1960s, in the Tashkent and Andizhan oblasts of Uzbekistan, the methylmercaptophos content in the water of studied well shafts was, by clearly underestimated data, 0.03 mg/l (MPC was 0.01 mg/l), of DDT was 0.6 mg/l (MPC was 0.1 mg/ I), and of HCH was 0.41 mg/l (MPC was 0.02 mg/l) [A49]. 

Figure 16. Determination of simazine concentration in water. In the upper part, the modulation of the Mach-Zehnder signal for one concentration, including the regeneration step. The lower part shows the calibration curve for six different simazine concentrations graphed for the slope of this signal versus the simazine concentration in the logarithmic scale.

C. Mouvel, R.D. Harris, C. Maciag, B.J. Luff, J.S. Wolknson, J. Piehler, A. Brecht, G. Gauglitaz, R. Abuknesha, and G. Isamil, Determination of simazine in water samples by waveguide surface plasmon resonance. Anal. Chim. Acta 338, 109-117 (1997). 

J. Gasc6n, E. Martinez, and D. Barceld, Determination of atrazine and alachlor in natural waters by a rapid-magnetic particle-based ELISA influence of common cross-reactants deethylatrazine, deisopro-pylatrazine, simazine and metolachlor. Anal. Chim. Acta 311, 357-364 (1995). 

Abel et al. [389] determined simazine in estuary water by adsorption on a Ci8 SPE cartridge followed by determination by HR-GC using a nitrogen-phosphorus specific detector. 

In several AT studies, pesticide levels in the Ebro were found to be high. Hildebrandt et al. [50] found a homogeneous contamination pattern from atrazine (and also from simazine from May 2000) in intensive Rioja cultivation areas throughout the Ebro. Nearer to the delta, Barata et al. [72] found high levels of bentazone, methyl-4-chlorophenoxyacetic acid, propanil, molinate and fenitrothion in water, while Kuster et al. [71] found low concentration levels of atrazine and simazine at the delta, but high levels of other pesticides used in rice cultivation. Importantly, Hildebrandt et al. [50] found that levels of pesticides in groundwater... 

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