Question

geologists are studying the impact of volcanic eruptions on nearby lakes and rainwater. they collected data on the ph levels of lakes and rainwater near five different volcanoes.
based on this data, which conclusion can be made about the effects of volcanic eruptions on water quality?
volcanic eruptions cause rainwater ph levels to remain neutral and lake ph levels to increase.
volcanic eruptions have no significant effect on the ph levels of lakes or rainwater.
volcanic eruptions generally lead to lower (more acidic) ph levels in rainwater.
volcanic eruptions cause rainwater to become more basic while lake ph levels remain unchanged.

Explanation:

Looking at the pH levels of nearby lakes and rainwater (pre - eruption and post - eruption):

• For Mount St. Helens: Pre - eruption (rainwater) pH = 5.2, post - eruption (rainwater) pH = 4.5.
• For Kilauea: Pre - eruption (lake) pH = 6.8, post - eruption (rainwater) pH = 5.6.
• For Mount Etna: Pre - eruption (lake) pH = 4.9, post - eruption (rainwater) pH = 4.2.
• For Taal Volcano: Pre - eruption (lake) pH = 5.0, post - eruption (rainwater) pH = 4.3.
• For Krakatoa: Pre - eruption (lake) pH = 6.5, post - eruption (rainwater) pH = 5.0.

In all cases, the pH of rainwater (and in some cases lake water) has decreased (become more acidic) after volcanic eruptions.

Answer:

Volcanic eruptions generally lead to lower (more acidic) pH levels in rainwater.