Passage III
Pore water is water in the pores of subsurface material. Pore water chemistry in 2 wetlands—a fen and a bog—was studied during a 1990 summer drought and again the next summer, which had normal rainfall. The primary water supplies for fens and bogs are, respectively, groundwater and rainfall. Figure 1 shows the methane (CH4) gas concentration in the pore water at various depths in the fen and the bog. Figures 2 and 3 show the pore water conductivity (which is directly proportional to the concentration of dissolved ions) and pH at various depths in the fen and the bog, respectively. Also shown are the locations of the water table, the peat (partially decomposed plant material) layer, and the mineral soil layer.
Figures adapted from Edwin Romanowicz, Donald Siegel, and Paul Giaser. “Hydraulic Reversals arid Episodic Methane Emissions During Drought Cycles in Mires.” ©1993 by the Geological Society of America.
13. According to Figure 2, the conductivity of fen pore water in 1990 at a depth of 2.5 m was closest to which, of the following?
Your Answer is
Correct Answer is C
Explanation
Because the question is about the conductivity in 1990, look at the solid line representing 1990 in the picture on the left in figure 2. It can be seen that when the vertical coordinate depth is 2.5 m, the horizontal coordinate is about 600