How does acid rain affect soils with high buffering capacity versus low buffering capacity?

• A. Soils with high buffering acidify more easily
• B. Soils with low buffering resist pH change
• C. Soils with high buffering resist pH change; low buffering soils acidify more easily
• D. Buffering capacity has no effect on acid rain

Answer: (C)

Buffering capacity in soils determines how much the pH shifts when acid rain is added. Soils with high buffering contain substances that neutralize hydrogen ions, such as carbonate minerals, clay surfaces, and organic matter that release basic cations. When acid rain brings in H+, these buffering reactions consume the extra hydrogen and keep the pH from dropping quickly, so the soil resists pH change. Soils with low buffering have fewer neutralizing substances, so the added acidity isn’t offset as well and the pH falls more easily, leading to acidification. Over time, repeated acid input can wear down even high-buffering soils, but the immediate effect is that high buffering resists pH change while low buffering acidifies readily. That’s why the statement describing high buffering resisting pH change and low buffering soils acidifying more easily is the best fit.