Certified Professional Horticulturist (CPH) Practice Exam

Water alkalinity measures the ability of water to stabilize or buffer which of the following?

1. Nutrients

2. Acidity

3. Excess evaporation

4. Microbes

The correct answer is: Acidity

Water alkalinity refers to the capacity of water to neutralize acids. It is primarily due to the presence of bicarbonates, carbonates, and sometimes hydroxides in the water. When water has high alkalinity, it can effectively buffer the pH, making it stable against changes caused by acid addition. This means that if an acid is introduced to the water, the alkalinity will work to counteract the pH drop, thereby stabilizing the acidity level in the water. In contrast, while alkalinity can influence nutrient availability and microbial activity indirectly, it does not measure their stabilization directly. Excess evaporation impacts concentration rather than alkalinity and thus is unrelated to the buffering capacity of water. Therefore, the focus of water alkalinity is specifically on its ability to buffer or stabilize the acidity.