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.

15. Which of the following is the most likely explanation for the difference in the depth of the bog water table in the 2 years?

Answer and Explanation

Your Answer is

Correct Answer is D

Explanation

The third line of the first paragraph of the article says...during a 1990 summer drought and again the next summer, which had normal rainfall. So the reason for the difference in the water table of bog in these two years is because of the rainfall, the rainfall in the dry period Less than normal times, so option D is in line