What is the first product of the decomposition of organic matter that indicates "fresh pollution"?

The correct answer is ammonia, which is produced as the first significant byproduct of the decomposition of organic matter. When organic material breaks down, various microorganisms, particularly bacteria, play a crucial role in this process. Initially, they decompose proteins, releasing amino acids that are further broken down into ammonia through a process called ammonification. The presence of ammonia can be an indicator of "fresh pollution" because it signifies recent organic material decomposition and points to an active presence of organic waste in an environment, such as contaminated water systems or impacted soil.

In the context of environmental health and pollution assessment, understanding that ammonia is a primary indicator highlights the importance of monitoring waters for signs of recent organic contamination. This can inform necessary interventions to restore water quality or mitigate further pollution.