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.

14. Based on Figure 2, if the pH of pore water in the fen at a depth of 2.7 m had been measured in the summer of 1991, it would most likely have been closest to which of the following?

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

I thought the question was about pH in 1991, so look at the dotted line in the picture on the right in figure 2 representing 1991. According to the trend of the line segment, it can be inferred that when the depth of the ordinate is 2.7 m, the pH of the abscissa is about 7