How would one describe the pH trend at greater sediment depths?

• A. It increases dramatically.
• B. It remains stable.
• C. It decreases.
• D. It fluctuates.

Answer: (C)

In sediment layers, pH tends to decrease with greater depths due to several factors. As organic material decomposes, it produces acids, which lower the pH. Additionally, the accumulation of carbon dioxide from microbial respiration can form carbonic acid when it interacts with water, which further contributes to the decline in pH levels.

This trend reflects the biochemical processes occurring in sediment, where the presence of organic matter and microbial activity influences the acidity of the environment. Consequently, the deeper one goes into sediment, the more pronounced these acidifying processes become, leading to a general decrease in pH. Understanding this trend is important for studying sediment chemistry and the implications it has for aquatic ecosystems and biogeochemical cycles.