Passage V

Nutrients in seawater are removed by phytoplankton and other marine organisms. Figure 1 shows the concentrations of 3 nutrients—nitrate (NO3—), dissolved inorganic phosphorus (DIP), and silicic acid(H4SiO4)—at various depths in the Atlantic, Pacific, and Indian Oceans. Table 1 shows the average concentrations and the estimated residence times (how long an ion or molecule of a nutrient remains in the ocean) for the 3 nutrients in deep (> 3 km) Atlantic and Pacific waters. Figure 2 shows how the NO3— concentration in Pacific surface waters (< 0.3 km depth) varies with latitude.

Figure 1 adapted from J. Andrews, P. Brimblecombe, T. Jickells, and P. Liss, An Introduction to Environmental Chemistry. @1996 by Blackwell Science Ltd.

Figure 2 adapted from James Murray et al., "Physical and Biological Controls on Carbon Cycling in the Equatorial Pacific." @1994 by the American Association for the Advancement of Sclence.

26. A scientist hypothesizes that the highest average NO3— concentration in Pacific surface waters would be found at the equator (0° latitude). Is this hypothesis supported by the data in Figure 2?

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

In the question stem, it is said that the Pacific waters contain the highest concentration of NO3- in the equatorial region, but it can be seen from figure 2 that the highest concentration is around 3oS, so The question stem is wrong, the area with the highest concentration should be south of the equator