Phytoremediation Of Rape For Arsenic In The Multiple Contaminated Soils In GAP Bases Of Ligusticum Chuanxiong

Faced on the serious problem of export was limited for the superstandard qualification of heavy metals in the Traditional Chinese Medicine (TMD) of Ligusticum Chuanxiong produced in the base of good agriculture practice(GAP) in Dujiangyan City, Sichuan Province, the aim of this thesis was to investigated the phytoremediation of arsenic combined pollution soils in the GAP Base of Ligusticum Chuanxiong based on our group's series works. When compared with the traditional method of soil remediation, the phytoremediation of soils has the merit of low cost, in-situ remediation, no secondary pollution, and so on. The main contents researched are following:(1) Analysis of arsenic in the environment of the GAP Base of Ligusticum ChuanxiongThe was no superstandard phenomena of arsenic concentration both in irrigation water and fertilizer used in the GAP Base. The concentration of arsenic in soils of the GAP Base was between 10.30 ~ 14.78 mg/Kg and with average value of 12.00 mg/Kg, which was higher than that in soils of Chengdu area and even higher than the background value in soils around China. The soil surface has introduced arsenic pollution by human's activities.(2) Screening of arsenic remediation plant used in phytoremediationAccording to the situation of the agricultures in GAP Base of chuanxiong, the accumulations of arsenic in several plants were studied. It is found that the distribution characteristic of arsenic in the cabbage, rice and garlic was the underground partï¹¥aboveground part, while that in the soybean and rape was leaf ï¹¥rootï¹¥stem. So the soybean and the rape have the potential to remediation of arsenic from the contaminated soils.(3) Effect of arsenic concentration for rape growth in Cd, Hg and As combined pollution soilsWhen the concentration of arsenic added in the combined pollution soils (Cd = 3 mg/Kg, Hg = 0.5 mg/Kg ) was less than 20 mg/Kg, it was proved that the arsenic promoted the growth of rape from aspects of the change in the rape germination, root length, plant height and dry weight in each part. While the concentration of arsenic added in was more than 40 mg/Kg, it was found that the root cutting lead to the death of the rape in the process of growth. It was also proved that the rape growth was inhibited seriously by aspects of the change in the rape root length and plant height.(4) Enrichment characteristic of rape for arsenic in Cd, Hg and As combined pollution soilsThe distribution character of arsenic in the rape planted in the combined pollution soils was root > leaf > stem. The transfer coefficient of leaf for arsenic was decreased from 9.28 to 1 in the blank rape leaf;In the combined pollution soils, with the increasing of Cd and As concentration can accelerate the enrichment of arsenic in root and stem in rape and prohibit the transfer of arsenic from toot and stem to leaf. The inhabitation degree of the transfer coefficient for rape leaf was the positive correlation with the concentration of Cd and As in soils; Appropriate mount of Hg in the soils can increase the transfer coefficient of arsenic to stem and leaf in rape.(5) Effect of citric acid and EDTA for enrichment of arsenic in rapeThe seed almost can't germinate when EDTA concentration was at 1.0 g/kg, so the EDTA produce great poisonous effect to the seed of rape, and the EDTA can inhibit arsenic transfer to the leaf of the rape. Compared with EDTA, the citric acid was not so great poisonous to the rape, and it can promote the enrichment of the arsenic in the rape root and stem. Moreover compared with the blank rape, the citric acid can improve the ability of arsenic to transfer to the rape stem. While the transfer coefficient of arsenic by the leaf was always inhibited by the citric acid in the soils, and the inhibit degree was the positive correlation with the concentration of the citric acid.