ACT真題每日一練9.2

　　Science Question for Wednesday, September 2nd, 2015

　　Passage I

　　The following table represents the concentration of ions and dissolved gases in the sediment at the bottom of an ocean. A depth of 0 centimeters (cm) represents the top of the sediment. The concentrations are expressed in parts per million (ppm). The acidity of a solution is represented on a scale known as pH. A pH of 1 is very acidic, a pH of 7 is neutral, and a pH of 14 is very basic.

　　Table adapted from R.M. Atlas and R. Bartha, Microbial Ecology: Fundamentals and Applications.

　　©1981 by Addison-Wesley Publishing Company.

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　　A researcher wants to determine whether an unidentified sediment sample was drawn from a depth of 15 cm or 20 cm. Based on the information in the table, which of the following would NOT confirm the depth of the sample?

　　A. O2 concentration

　　B. Fe3+ concentration

　　C. S2– concentration

　　D. pH