What primarily affects the saturation point of calcium carbonate?

The saturation point of calcium carbonate is primarily affected by pH. When the pH of water changes, it influences the solubility of calcium carbonate. Calcium carbonate is more soluble in acidic conditions, meaning that as the pH decreases (the water becomes more acidic), the saturation point for calcium carbonate is also lowered. Conversely, in alkaline conditions (higher pH), calcium carbonate may precipitate out of solution, leading to lower solubility and higher saturation levels.

While temperature, salinity, and total alkalinity do impact the overall chemistry of water, they do so in conjunction with pH. For instance, increasing temperature can increase the solubility of many compounds; however, in the specific case of calcium carbonate, it is the pH variance that primarily drives saturation levels. Salinity can alter ionic strength but does not have as direct an impact on calcium carbonate saturation as pH does. Total alkalinity, which involves the buffering capacity of water, also plays a supporting role but is secondary to the influence of pH when determining the saturation state of calcium carbonate in water.