Rhine water temperature

The transport of disulfoton from water to air can occur due to volatilization. Compounds with a Henry s law constant (H) of <10 atm-m /mol volatilize slowly from water (Thomas 1990). Therefore, disulfoton, with an H value of 2.17x10" atm-m /mol (Domine et al. 1992), will volatilize slowly from water. The rate of volatilization increases as the water temperature and ambient air flow rate increases and decreases as the rate of adsorption on sediment and suspended solids increases (Dragan and Carpov 1987). The estimated gas- exchange half-life for disulfoton volatilization from the Rhine River at an average depth of 5 meters at 11 °C was 900 days (Wanner et al. ] 989). The estimated volatilization half-life of an aqueous suspension of microcapsules containing disulfoton at 20 °C with still air was >90 days (Dragan and Carpov 1987). 

Fig. 11 Moving average (period 22 weeks) of water temperature lower curve) and water discharge (upper curve) in the Rhine...

Figure 7. Variations in the toxicity of Rhine water at Gorinchem -, river discharge --, water temperature --------,...

Samples of river water were taken on August, 16-17, 1999 at 19 sampling sites on a longitudinal section of the Lippe river, North-Rhine Westphalia, Germany (see Fig. 1). They were scooped up from below the water surface at midstream and bottled in pre-cleaned glass flasks. Filled sample flasks were sealed free of air bubbles with glass stoppers and stored in the darkness at a temperature of approximately 4 °C. 

The reported half-lives for abiotic hydrolysis, photochemical transformation and primary degradation in Rhine River water samples were 170, 1,000 and 7-41 days, respectively (Warmer et al., 1989). Hydrolysis half-lives at 69.0°C and pH values of 3.03 and 6.99 were 0.60 and 0.61 days, respectively. At a temperature of 48.0°C and pH of 11, however, the half-life was reduced to 0.12 hours (Ellington et al., 1986). 

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