Final answer:
DNAPLs and LNAPLs behave differently upon entering the subsurface soil due to their density differences, with DNAPLs tending to sink and LNAPLs to float. Bacterial pathogens can survive in subsurface environments and either contribute to pollution or its remediation. Bacteria can form biofilms and affect soil characteristics, with their survival dependent on various environmental factors.
Step-by-step explanation:
When DNAPLs (Dense Non-Aqueous Phase Liquids) enter the subsurface soil, they tend to sink downwards due to their higher density compared to water, potentially reaching the groundwater. LNAPLs (Light Non-Aqueous Phase Liquids) behave differently as they are less dense than water and typically float on the water table. Both can be difficult to remediate and may persist in the environment for a long time.
Bacterial pathogens entering subsurface soil can survive and potentially move with water flow. Their survival is influenced by factors such as temperature, pH, and availability of nutrients. Bacteria like Gram-positive bacteria, can decompose organic matter in the soil, but some can also cause diseases. As bacteria move or are transported through the soil, they can contribute to the contamination or remediation of pollutants depending on their metabolic activities.
In specific environments such as the alimentary canal, bacteria are usually destroyed by natural defenses, but within subsurface environments, certain species can survive and even play a role in the development of biofilms. These biofilms can affect the permeability and chemistry of the soil, leading to various ecological impacts. Moreover, studies like those conducted on Lake Constance show that bacteria can remain active in deep, aged lake sediments, highlighting their resilience.