Ecological Risk Assessment Of Contamination Soil By Nickel

As the nickel has the good performance, may make stainless steel, corrosion resisting alloy, ceramic, battery and so on, it has applied very widely in many areas of petroleum, automobile, food processing, mold, presswork, textile, medicine, etc. The nickel ore mainly distributes in places such as Sichuan, Gansu, Xinjiang, Yunnan of China.The nickel is essential in minute amounts for the proper growth and metabolism of living organisms, and an element of latent toxicity. The minute amounts nickel in the soil may stimulate the plant growth, in the contrary, the excessive nickel can hinder the plant growth, grow badness, cause the harm to the plant until died. The nickel may stockpile in plants. When the plants enter the food chain that nickel content surpassed a normal amount, the animal and human's health will be affected. When the exposed slag and tailings are corroded differently in degree, the water bodies, the soil and the air will be further polluted. Then the ecological equilibrium will be destroyed, the serious polluted environment by nickel will form, the harmonious environment will not be redeemed.This paper start with comparison about the toxic action to the plants by heavy metal nickel in soil and the resistance of plant. To observe the influence of nickel to the plant seedling growth, analyse dosage-effect relations between the dosage change of extraneous nickel with the plant growth amount, find the 10% inhibition concentration (EC10), median inhibition concentration (EC50) and 90% inhibition concentration (EC90) of plants through the dosage - effect curve. To compare with EC50s of plants, relate the influence of nickel to the plant seedling growth state, select a plant which response to toxic effect of the heavy metal nickel is more sensitive and better. The result may make preparation further for the experiment about the influence of root elongation inhibition rate by the nickel in the soil. Conclusion:(1) To draw conclusions from nine plants' growth. In the fluvio-aquic soil, the Rice and Long Bean's toxic nickel concentration is about 75mg/kg; the Celery, the Bok Choy, the Barley and the Mustard's toxic nickel concentration is about 150mg/kg; the Spinach, the Green Chili and the Tomato's toxic nickel concentration is about 300mg/kg. In the red soil, the Celery, the Bok Choy, the Long Bean and the Tomato's toxic nickel concentration is about 12.5mg/kg; the Spinach's toxic nickel concentration is about 25mg/kg; the Rice, the Barley, the Mustard and the Green Chili's toxic nickel concentration is about 50mg/kg.(2) After processing two soils with different nickel concentrations, all seed's germination rate were affected. In low concentrations (fluvio aquic soil 150mg/kg, red soil 12.5mg/kg), the seed's germinationrate is above 80%. Along with the concentrations increase, seed germination rate gradually reduces. After the seed germinated, the root growth was restrained in degree. Moreover, nine plants growth put up relative patience to the nickel all. Through comparing with the germination rate and the growth state of nine plant in two soils, the Barley seed germination was the best, patience was stronger, in later period, its growth state displayed continuous transformation well along with the nickel concentrations increase. So the Barley was taken for indicator plant for next experiment is suitable.(3) The different soil and different plant's inhibition concentration is different The EC50 must be better for forecasting plant toxic concentration.(4) Except the Rice, the EC10 and EC50 of the red soil were all smaller than the fluvio aquic soil, that indicated the plant toxic concentration in red soil was smaller than in the fluvio aquic soil. The fluvio aquic soil's cushioning effect to the nickel toxic effect was strong than the red soil's. This means that some physiochemical property of the soil influence the toxic effect. In the fluvio aquic soil, the Long Bean was the most sensitive plant, EC50 was 69mg/kg: the Tomato was the fastness strongest plant, EC50 was 362mg/kg.. In the red soil, the Bok Choy and the Tomato were the most sensitive plant, EC50 were 11mg/kg and 11.2mg/kg, the Rice was the fastness strongest plant, EC50 was 71.8mg/kg.(5) There were a strong linear relationship between the roots elongation suppression rate and the nickel density in the fluvio aquic soil, paddy soil and red soil. The correlation coefficient above 0.97. The toxicsensitive degree of barley to the nickel toxicity was different on three kind of soils. Along with pH increasing, the barley root elongation suppression rate reduces.Through this research, we can grasp and profit research method from the toxicity of heavy metal on soil and the ecology risk evaluation, overseas. The result provided the theory method basis for researching soil of nickel pollution area or all that heavy metal pollution area in our country, and selecting the plant species on vegetation restores.