Effect Of Soil Water Regime On As Uptake In Rice And Remediation Of Potentilla Supina To Polluted Ricefield In Smelter Area

With the development of industry and agriculture modernization, The soil pollution in China is being increased seriously by heavy metal, and the ricefield which surrounds metallurgy area and is polluted by heavy metal have higher risk. This leads to lose a mass of ricefield. Moreover, the polluted ricefield can not be used to plant rice, or the rice has high levels of heavy metal concentration, causing serious harm to people's life safety. Therefore finding out the ricefield pollution levels near smelter, researching the best flooded way of dry rice in pollution soil and the difference of heavy metal uptaking between two rice varieties, and remediating mine pollution fields all have important significance. On the basis of the survey, this study site-directly collected high and low heavy metals pollution soil in Hangzhou smelter suburb, Zhejiang province. Using dry rice (Baxi dry rice), paddy rice (Zhongxiang NO.1) and Potentilla supina as experimental plants, through the pot and hydroponics experiments, the heavy metals uptake of shoot of different rice varieties (Baxi dry rice, Zhongxiang NO. 1) was studied under arsenic and cadmium pollution soil and different flooded way(aerobic, flooded, intermit irrigation, prophase intermit irrigation aerobic after heading). Meantime, the tolerance to heavy metal and phytoremediation potential of Potentilla supina was explored. The results were as follows:1. In the soil arsenic concentration of 6.49 mg kg^-1, after the addition of arsenic 15 mg kg^-1, dry rice growth under the aerobic was inhibited significantly. The toxic symptoms such as the slow growth rate of plant with yellow leaves, low height and failure of heading at maturity were very serious. It was shown that dry rice under the aerobic had higher sensitiveness to arsenic. Under the flooded treatment, the dry rice biomass and arsenic uptake is not significant, but heavy metals uptake increased markedly than under the treatments without addition of arsenic. It was indicated that the exogenous arsenic increased the uptake of copper, zinc, lead and cadmium by dry rice under the flooded treatment. 2. For Baxi dry rice, the biomass is greater and the arsenic uptake is lower under intermit irrigation, with non-significant difference compared with the flooded and prophase intermit irrigation aerobic after heading treatments. But the heavy metal uptake is significantly lower than the latter two treatments, so the intermit irrigation is the most suitable water management pattern of dry rice.3. The biomass of Baxi dry rice and Zhongxiang NO. 1 under the flooded treatment was higher than that under the aerobic treatment in arsenic high pollution soil. The arsenic concentrations of brown rice from paddy rice flooded, dry rice flooded and paddy rice aerobic were 0.51 0.33, 0.16 mg kg^-1, respectively, it was showed that dry rice and paddy rice both are arsenic low accumulation varieties. The two varieties' adsorption ability of heavy metal in flooded treatment (except lead) was very similar, and the concentrations of heavy metal were significantly higher than that under the aerobic treatment.4. Although Potentilla supina wasn't in line with the criteria of hyperaccumulation plants, it had a strong ability of absorbing heavy metal. Because this species is a hygrophilous plant prefering to habitating wet and low humid soils, it has the potential function of remediating the rice paddies near the smelter.