The invention relates to a method for determining ecological risks, particularly to an 
ecological risk assessment method of heavy 
metal in river basin 
sediment based on the 
toxicity effect. The assessment method mainly comprises the following steps: 1, screening main 
aquatic organisms in the river basin, 2, sampling 
sediment, and determining and detecting types of heavy 
metal, 3, detecting the heavy 
metal concentration in the 
sediment, 4, collecting the heavy metal release coefficient, 5, collecting heavy 
metal toxicity data and fitting the data, 6, determining the heavy metal HC5 value according to a fitted equation, 7, calculating the heavy 
metal toxicity coefficient, 8, calculating the heavy 
metal toxicity response coefficient, and 9, calculating the heavy metal 
ecological risk index, and the method can further comprise a step 10 of calculating the comprehensive 
ecological risk index of various types of heavy metal. Compared with the prior art that the crustal abundance is adopted to indirectly and roughly estimate the metal 
toxicity effect, the assessment method provided by the invention can more accurately reflect the ecological risks, caused by the heavy metal in the sediment, to the 
aquatic organisms in the river basin.