Keywords: 
• heavy metals /
• algae infrared radiation testing /
• binary combined effects

Abstract: In order to test the feasibility of the algae infrared radiation testing method for binary combined effects, Cu²⁺, Fe³⁺, Mn²⁺, Al³⁺, Cr³⁺, Hg²⁺, Cd²⁺, Pb²⁺, Zn²⁺ were used in the experiments. The results showed that 15 binary combinations were found with a 0.5 (g·L^-1) and 0.25 (g·L^-1) ratio of reference concentration in mixture liquids and the single heavy metal liquids; 10 binary combinations having reference concentration ratio of 2 (g·L^-1) and 1 (g·L^-1) in mixture liquids and the single heavy metal liquids; and 11 binary combinations having reference concentration ratio of 1 (g·L^-1) and 0.5 (g·L^-1) in mixture liquids and the single heavy metal liquids. Antagonistic action, additive action and synergistic action are found in the 36 binary testing combinations. As for 14 antagonistic action results, reappearance rate of single groups and that of multiple groups are 50%-100% and 93% respectively; recurrance rate of single groups and that of multiple groups are 67%-100% and 100% respectively. In the 21 additive action groups, reappearance rate of single groups is 50%-100% while that of multiple groups is 86%; the recurrance rate of single groups is 67%-100% while that of multiple groups is 100%. In the only one group of synergistic action the recurrence rate is 67%. In all 36 binary combination testing groups, 50%-100% results are reproducible, and the occurance rate is 86%; 67%-100% results are repeatable, and the occurance rate is up to 100%. The above analysis shows that there is good diversity, reproducibility and repeatability in the results of 36 binary combination testing groups. It is indicated that the quality of evaluation result of the algae response temperature and response difference can be ensured by the test conditions, the algae temperature test method and the three index evaluation method. The quality of the analysis results can be controlled by the reference concentration analysis method and the combined effects evaluation method. The sensitive concentrations for harmful substances can be found in the algae response. The reference concentration analysis method can be used to analyze the response concentration of the harmful substances in the algae response, and therefore, the algae infrared radiation testing method can be used to test the binary combined effects of heavy metals, pesticides, organic drugs, and antibiotics.