| Guangxi as a "township of nonferrous metals", has the highest mining intensity of manganese (Mn) in the country, which has resulted in serious soil pollution. How to solve the environmental harm brought by the manganese mining is imminent. Phytoremediation is a cheap and effective bioremediation technology of soil heavy metal pollution. However, suitable plants for Mn hyperaccumulation and enrichment are relatively rare. Camellia oleifera is one of the main economic crops and widely cultivated in Guangxi; its production in Guangxi accounts for 16.9% of total national production. It has shown good capacity of Mn enrichment. Therefore, based on investigation and sampling in Hezhou manganese mine area, in this study potting experiments with soil and sand was conducted to verify the Mn enrichment capability of Camellia oleifera. The effect of different types of fertilizers, lime, chicken manure and humid acid on soil Mn morphological changes and on the antioxidant enzyme system in Camellia oleifera were investigated. The effect of different additives to the efficiency of bioremediation on Mn-polluted soil were explored. The main research results are as follows:1. The Mn contents were 1346.9?7269.1 mg-kg-1 soil in Hezhou manganese mine area. Mn contents in Camellia oleifera followed as leaf> stem> root. Mn content in leaves and stems were 1502.11-9135.lmg-kg-1 and 288.9-3512.9 mg·kg-1, respectively. TFleaf/root was 3.0?53.2, TFstem/root was 1.2-13.7. Although not reaching the standard for Mn hyperaccumulation plants (10000 mg·kg-1), it showed good tolerance and enrichment towards Mn pollution.2. Under the culture conditions with soil and sand, Camellia oleifera height and Mn content showed increase-decrease trend with the increase of Mn level. Under culture with soil, the highest Mn content in Camellia oleifera leaves occurred under 1000 mg Mn·kg-1 treatment, reaching 8341.83 mg·kg-1, while Mn content in the stem reached 3613.24 mg·kg-1. Under culture with sand, the highest Mn content in Camellia oleifera leaves occurred under 5mmol Mn-L-1 treatment, reaching 28462.4 mg-kg-1. Camellia oleifera began to show poisoning symptoms under 200mg-kg-1 Mn in soil culture and under 10 mmol·L-1 Mn in sand culture. But new leaves were still growing. The phenomenon with leaves fallen off occurred under 1000mg-kg-1 Mn in soil culture and under 15 mmol-L-1 Mn in sand culture. The results indicate that a certain concentration of Mn can promote the growth of Camellia oleifera.3. The content of exchangeable Mn and the activities of POD?CAT?APX in soil were all increase to some extent with the addition of N, P, K fertilizers, promoting the Mn absorption in the Camellia oleifera leaves. However, the plant height, plant weight, the content of chlorophyll a & b and PCs of Camellia oleifera declined compared to the control. The optimal concentration of N fertilizer was the N100 treatment. The addition of P fertilizer decreased the content of Mn in leaf of Camellia oleifera in soil A while increased the content of Mn in stem of Camellia oleifera as well as the content of The chlorophyll a & b, MDAs and the activities of POD, CAT, APX in soil B. The optimal concentration of P fertilizer is P400 treatment. The addition of K fertilizer increased the content of Mn in stem, but decreased that in leaf of Camellia oleifera in soil A. The addition of K fertilizer increased the content of Mn in both stem and leaf of Camellia oleifera in soil B. K fertilizer The addition of K fertilizer promoted the contents of the chlorophyll a & b and MDAs in leaf of Camellia oleifera. Low concentration of K fertilizer decreased the activity of SOD; and the activities of CAT. POD, APX decreased with the increase of K fertilizer addition. The optimal concentration of K fertilizer was K200 treatment.6. With lime addition, the content of exchangeable Mn in soil decreased, followed by the decrease of the content of Mn in leaf and the increase of that in stem of Camellia oleifera. The content of Mn in stem increased with the increase of lime addition. Added Lime increased the content of chlorophyll, as well as the activities of POD and CAT, but decreased the height and the weight of Camellia oleifera as well as the activity of SOD. The content of SH and PCs increased significantly than control (P<0.05). The optimal concentration of lime addition was S1 treatment.7. With the addition of chicken manure, the content of exchangeable Mn in soil increased. The content of Mn in leaf of Camellia oleifera increased under the AJ2, AJ3, BJ1, BJ2, BJ3 treatments. The content of chlorophyll a & b and the activities of SOD, POD, CAT and APX increased as well. The optimal concentration of the addition of Chicken manure was J3 treatment.8. With the addition of humic acid, the content of exchangeable Mn in soil decreased. Compared to the control, the content of Mn in the leaf of Camellia oleifera decreased under low concentration of humic acid, but increased under high concentration of humic acid. The height,weight and the content of chlorophy of Camellia oleifera increased with the addition of humic acid. The activity of SOD changed insignificant. The activity of POD changed insignificantly in soil A, but significantly in soil B. The activity of CAT increased compared to the control. The optimal concentration of added humic acid wass F3 treatment... |
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