2.4- Dinitrophenol Groundwater

In River R a pollution cloud of 2,4-dinitrophenol (see Illustrative Example 25.2) of duration At = 1 h and concentration Cin =50 ng L-1 is passing by Groundwater System S. Calculate the maximum concentration reached at the wells for the three regimes. Compare these values to the maximum concentrations reached 3 m away from the river. 

Remember that according to the approximation made for the dispersion coefficient, dis (Eq. 25-12), the Peclet Number does not depend on it. Therefore, the influence of the pump regime on the concentration at the well is not caused by a change of the transport conditions in the aquifer (e.g., flow time tw), but simply by the fact that more dinitrophenol enters the groundwater during the passage of the pollution cloud if u is large. 

On April 5, at noon, the 2,4-dinitrophenol concentration in River R at Groundwater System S (GWS, see Illustrative Example 25.1 and 25.2) suddenly increases from 0 to 50 ng L 1 and then remains constant. At what time does the concentration in the wells of the GWS reach 25 ng L-1 and 47.5 ng L 1, respectively Calculate the time for all three flow regimes. When are these concentrations reached 3 m from the river if no water is pumped from the wells (Natural Regime) ... 

Calculate the annual sinusoidal variation of the PCE concentration in the wells of Groundwater System S relative to the variation in River R. Compare this number with the relative variation of a nonsorbing chemical such as 2,4-dinitrophenol (see Illustrative Example 25.5). Determine the time lag of oscillation in the well relative to the variation in the river. Use all three flow regimes of Illustrative Example 25.1. 

The mobility of dinitrophenols in soils decreases with increase in acidity, clay, and organic matter content, but the mobility in soil will increase as the basicity of soil-water increases because the ionized form is more water soluble and moves faster through soil (Kaufman 1976). 2,4-DNP has been measured in groundwater from waste disposal sites (ATSDR 1988 Plumb 1991), indicating the possibility that these compounds leach from soil. Depending on the nature of soil and climatic conditions, the residence time of 2,4-DNP in soil has been determined to be <8-120 days (Kincannon and Lin 1985 Loehr 1989 O Connor et al. 1990). 

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