The researchers studied nitrogen and microbes in the sediments of the Songhua River. They found that some areas had high nitrogen levels, which could be a concern. Total organic nitrogen was the main form found in the sediment. Ammonium levels were highest in the Nenjiang River, while nitrate levels were highest in the main stream of the Songhua River. Certain genes related to nitrogen transformation were more abundant in the dry season. Factors like moisture, pH, and oxygen levels affected the microbes in the sediment.