The researchers studied nitrogen levels in the Ganjiang River during different seasons and at various locations. They found that nitrate was the main form of nitrogen, followed by ammonia, with very low levels of nitrite. Nitrate levels were higher in the dry season compared to the flood season. Ammonia levels were influenced by urban wastewater discharge. Nitrate levels increased downstream during the dry season but decreased slightly during the flood season. Tributaries with high nitrogen levels were likely impacted by agricultural and industrial activities in the surrounding areas.