The researchers studied water quality in the Liao river area. They checked if the water met specific quality standards and analyzed how water quality changed over time by looking at data from different points along the river. The study identified that most pollution in the area comes from organic sources, like sewage or waste. Places where pollution comes from specific points, like factories, are more concerning than pollution from the overall area. They found that the water quality levels weren't very high and pollution in the surface water is increasing over time.