A method for determining ecological risks of heavy metal pollution in river and lake sediments

A method for determining ecological risks of heavy metal pollution in sediments of a river or a lake, the method comprising:

• (1) collecting water body sediment samples to determine concentration levels of heavy metal pollutants at different positions of the water body sediments;
• (2) conducting statistic analysis on distribution characteristics of concentration data of various heavy metal pollutants in the water body sediments;
• (3) calculating an ecological risk index of a heavy metal pollutant using a formula Eri=Tri×C0i/Cri, wherein Eri represents an ecological risk index of an ith heavy metal pollutant;
• C0i represents a measured concentration value (mg/kg) of the ith heavy metal pollutant in the water body sediments;
• Cri represents the background value (mg/kg) of the heavy metal pollutant before industrialization;
• and Tri represents an ecological toxicity coefficient of the ith heavy metal pollutant;
• (4) conducting sampling calculation using a Monte Carlo method according to value distribution characteristics of C0i, wherein the sampling times is served as final sampling times when an average value of Eri is stable or when a difference of the average values of the two operations is less than 5%, and the corresponding operation result is a final result of Eri;
• (5) determining the distribution characteristics of the ecological risks of the ith heavy metal pollutant by drawing a distribution curve of Eri values to analyze a probability that the ecological risks appear at different risk levels with reference to a risk level classification standard, wherein a higher probability of the Eri value appearing at a high risk level indicates that a higher level of potential hazards is caused by the heavy metal pollutant to an ecological system and more necessarily the heavy metal pollutants are under control;
• (6) calcualting a total ecological risk comprehensive index HRI caused by the various heavy metal pollutants in the evalulated water body using a formula HRI=ΣEri to conduct the sampling calculation using the Monte Carlo method and to draw a cumulative probability distribution curve of the HRI values according to the sampling result;
• and
• (7) analyzing a probability that the total ecological risk comprehensive index HRI of the water body appears at different risk levels with reference to the risk level classification standard to determine the ecological risks of the heavy metal pollution in the sediments of the river or the lake.