Plant Monitoring And Assessment Of Combined Pollution Of Petroleum And Heavy Metal In Salted Soils

Petroleum and heavy metal which are typical soil environmental pollutants often exist simultaneously and distribute widely in saline soils. By studying petroleum and heavy metals pollution, the migration of pollutants transformation behavior under the combined pollution can be evaluated in saline soils properly. Reasonable control measures for pollutants can be taken with the help of important references provided by this study. By launching indoor pot experiment, the impacts of sole and compound pollution of petroleum and heavy metal on plant height, plant dry weight, chlorophyll content, catalase activity(CAT), soluble protein content and praline content have been studied. A kind of assessment method of saline soil environmental quality which evaluated combined pollution of petroleum and heavy metal by use of plant indicators have been established. The main findings are as follows:(1)The effects of oil on plant height, dry weight, content of chlorophyll, CAT, soluble protein, and free proline in Suaeda heteroptera Kitagawa were studied. Suaeda heteroptera Kitagawa were exposed to different oil concentrations in order to evaluate the responses of the plant to heavy metal stress. The results showed that the plants had tolerance threshold of2500mg·kg-1, under which the plants showed similar height, dry weight and physiological characteristics with that of control group. With increasing oil concentrations in soils, the chlorophyll contents in the plant declined obviously, CAT activities increased in a short period and then decline, the soluble protein contents of Suaeda heteroptera Kitagawa increased and then declined with time, the free proline in the plant increased significantly.(2)The effects of Ni and V on plant height, dry weight, content of chlorophyll, catalase(CAT) activity, soluble protein, and free proline in Suaeda heteroptera Kitagawa were studied. Suaeda heteroptera Kitagawa were exposed to different Ni and V concentrations in order to evaluate the responses of the plant to heavy metal stress. The results showed that the plants had tolerance threshold of36mg-kg-1for Ni and19mg-kg-1for V, under which the plants showed similar height, dry weight and physiological characteristics with that of control group. With increasing heavy metal concentrations in soils, the chlorophyll contents in the plant declined obviously, CAT activities increased in a short period(20d) and then decline, the soluble protein contents of Suaeda heteroptera Kitagawa increased in the former40d and then declined with time, the free proline in the plants increased significantly(p<0.05) with the increasing of heavy metal concentration.(3)The effects of oil and heavy metal compound pollution on plant height, dry weight, content of chlorophyll, CAT, soluble protein, and free proline in Suaeda heteroptera Kitagawa were studied. The results showed that the toxic effects of the mixture are greater than the sum of the two pollutant, indicating that oil and heavy metals(Ni+V) in the soil have a synergistic effect.(4) One method that use the plant dry weight inhibition rate(M) was established to evaluate the degree of soil pollution, M<10clean,10<M<20light pollution,20<M<40as moderately polluted, M>40severe pollution; soluble protein inhibition rate of the plant and chlorophyll inhibition rate ratio (N) for the ecological risk index, N <1considered mainly for large heavy metal contaminants in soil, with a big potential toxic, N>1considered the main pollutants in soil is oil, the potential toxic is small. This method was used to evaluate the soil sample1,4,8,12meters away from the wells in the Yellow River Delta, this method can not accurately draw the various types and levels of contaminants in soil, however, it can reflect the potential toxic of the soil.