How does acid deposition affect soil chemistry and nutrient availability?

How does acid deposition affect soil chemistry and nutrient availability?

• A. It increases soil pH and base cations.
• B. It leaches base cations (Ca, Mg, K), lowers soil pH, increases aluminum toxicity, reducing microbial activity and nutrient availability.
• C. It has no effect on soil chemistry.
• D. It only affects surface water, not soils.

Answer: (B)

The main idea is that acid deposition acidifies soil and disrupts nutrient availability by removing essential base nutrients from the soil and increasing toxic aluminum in the soil solution. When acidic rain or gases lower the soil pH, hydrogen ions push off base cations such as calcium, magnesium, and potassium from soil particles and organic matter. Those displaced base cations then leach away with water, depleting the soil’s fertility and lowering the pH even further. As the pH drops, aluminum becomes more soluble, raising Al3+ concentrations, which can be toxic to roots and hinder nutrient uptake. This combination also slows microbial activity, since many soil microbes prefer near-neutral conditions; reduced microbial activity means slower decomposition and nutrient cycling, further limiting nutrient availability for plants. Over time, continued acid input can deplete base cations and degrade soil fertility, making the effects persistent.

The main idea is that acid deposition acidifies soil and disrupts nutrient availability by removing essential base nutrients from the soil and increasing toxic aluminum in the soil solution. When acidic rain or gases lower the soil pH, hydrogen ions push off base cations such as calcium, magnesium, and potassium from soil particles and organic matter. Those displaced base cations then leach away with water, depleting the soil’s fertility and lowering the pH even further. As the pH drops, aluminum becomes more soluble, raising Al3+ concentrations, which can be toxic to roots and hinder nutrient uptake. This combination also slows microbial activity, since many soil microbes prefer near-neutral conditions; reduced microbial activity means slower decomposition and nutrient cycling, further limiting nutrient availability for plants. Over time, continued acid input can deplete base cations and degrade soil fertility, making the effects persistent.