Biodegradation is crucial for cleaning up contaminated groundwater. Microbes break down pollutants, with the most activity at the edge of the contamination. As the pollution moves, new attached microbial communities form on clean surfaces. These communities stabilize after about 100 days, regardless of the contamination level. The attached and floating microbial groups are different, with some organisms preferring to attach. The development of these communities is influenced by both planned and random factors, as well as the environment they are in.