The Effects of Freezing and Thawing on the Physiological Characteristics of Remediation Plants in the Combined Contaminated Soil of Petroleum Hydrocarbon and Cadmium

Artemisia vulgaris L. and Medicago sativa L. were used as remediation plants to investigate the effects of freezing and thawing on the physiological characteristics of remediation plants in the combined contaminated soil of petroleum hydrocarbon and cadmium (Cd). The results showed that compared with the single pollution stress, the relative conductivity of Artemisia vulgarisL. and Medicago sativa L. leaves increased significantly, chlorophyll content and plant net photosynthetic rate decreased significantly in the combined pollution of petroleum hydrocarbon and Cd, which presented that the remediation of compound pollution was more difficult than that of single pollution. Phytoremediation could effectively enhance the removal of pollutants in petroleum hydrocarbon and Cd contaminated soil, and the ability of Artemisia vulgaris to resist the pollution stress of Cd was higher than that of Medicago sativa, which showed better remediation potential for petroleum hydrocarbon and Cd contaminated soil. Although freezing and thawing could change the enzyme biological properties of soil, it has not shown obvious synergistic effect in the phytoremediation of petroleum hydrocarbon and Cd contaminated soil.