Question

sat practice question:
after a volcanic eruption spilled lava into north pacific ocean waters, a dramatic increase of diatoms (a kind of phytoplankton) near the surface occurred. scientists assumed the diatoms were thriving on nutrients such as phosphate from the lava, but analysis showed these nutrients werent present near the surface in forms diatoms can consume. however, there was an abundance of usable nitrate, a nutrient usually found in much deeper water and almost never found in lava. microbial oceanographer sonya dyhrman and colleagues believe that as the lava plunged nearly 300 meters below the surface it dislodged pockets of this nutrient, releasing it to float upward, given that
which choice most effectively uses data from the table to complete the statement?
o at 5 - 45 meters below the surface, the average concentration of phosphate was about the same in the seawater in the lava - affected area as in the seawater outside of the lava - affected area.
for both depth ranges measured, the average concentrations of nitrate were substantially higher in the seawater in the lava - affected area than in the seawater outside of the lava - affected area.
for both depth ranges measured in the seawater in the lava - affected area, the average concentrations of nitrate were substantially higher than the average concentrations of phosphate.
in the seawater outside of the lava - affected area, there was little change in the average concentration of nitrate from 75 - 125 meters below the surface to 5 - 45 meters below the surface.

Explanation:

Step1: Analyze the first option

The phosphate concentration in lava - affected area (5 - 45 meters) is \(0.17\) and outside is \(0.14\). They are not about the same.

Step2: Analyze the second option

For nitrate:

• In 5 - 45 meters: Lava - affected (\(3.1\)) vs outside (\(\leq0.03\))
• In 75 - 125 meters: Lava - affected (\(0.4\)) vs outside (\(\leq0.01\))

In both depth ranges, nitrate in lava - affected area is much higher.

Step3: Analyze the third option

In 5 - 45 meters: Nitrate (\(3.1\)) and phosphate (\(0.17\)) (nitrate higher). In 75 - 125 meters: Nitrate (\(0.4\)) and phosphate (\(0.09\)) (nitrate higher). But the option says "for both depth ranges measured in the seawater in the lava - affected area", but the comparison should be relevant to the context of the problem (about the difference between lava - affected and non - lava - affected in terms of nutrients for diatoms). The second option directly compares lava - affected and non - lava - affected which is more in line with the problem's context.

Step4: Analyze the fourth option

For nitrate outside: In 5 - 45 (\(\leq0.03\)) and 75 - 125 (\(\leq0.01\)). There is a change.

Answer:

For both depth ranges measured, the average concentrations of nitrate were substantially higher in the seawater in the lava - affected area than in the seawater outside of the lava - affected area.