Progress in research on river nutrient criteria development methods

River nutrient criteria is an important basis for the comprehensive evaluation of river nutrient status and the revision of surface water standards. The latest research progress of the methods for the formulation of river nutrient criteria at home and abroad was systematically discussed, and the procedures and candidate indicators for the formulation of river nutrient criteria put forward. The statistical analysis method, model inference method and pressure-response model method for the determination of river nutrient criteria were emphasized, and the development trend of the method for the determination of river nutrient criteria prospected. Through combing and comparison, it was proposed that among the formulation methods of river nutrient criteria, the reference section method in the statistical analysis could best reflect the natural state of the river, but the use of historical river data and the data of the river with less human interference would lead to the over-protection of the river, and the neglect of the impact of natural factors such as climate change would also lead to the under-protection of the river. The model inference method needed a large amount of data to construct a functional model representing the characteristics of water body, and its complexity made the application of this method more difficult. At present, the pressure-response model was a hot topic for scholars at home and abroad, but the response mechanism between nutrient concentration in rivers and biogenic and special sensitive populations under the influence of human activities and climate change still needed to be deeply explored, and the close combination of nutrient criteria formulation and river management needs should be strengthened.