珠三角农耕湿地重金属生化脱毒实验研究及应用
- 来源：新浪科技 作者：Freedom 时间：2008-05-05 21:05:35
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中国广东省佛山市第二中学 “绿色假日”环保科技活动小组
高三学生 郭阳 吴俊宏 余思思
指导老师：周惠芳 苏永善
针对珠江三角洲地区农耕湿地中重金属污染物在水与土壤之间迁移频繁，难于清除的特点，本研究摒弃从“水- 壤”环境中直接清除污染物的传统修复方法，根据湿地水壤系统环境因子对重金属的吸附和解吸特性，探究三种不同水环境中，作物对重金属的吸收抑制效果和规律，寻找新型、可行的重金属污染“无毒化”途径，达到脱毒的目的。实验以“水- 壤”环境的铅、镉、汞三种典型污染物为研究对象，通过探究不同水环境和处理条件下几种典型蔬菜重金属含量变化，以此追踪和指示农田水系和土壤中重金属变化及“脱毒”效果。本研究从当地农田土壤中多重筛选驯化,获得优势目标微生物，然后采用“微生物-酸碱缓冲调节”的方法进行脱毒实验。研究结果显示：圆褐固氮菌为优势目标微生物，它具有耐重金属和常用农药污染、容易增殖、适合珠三角气候和湿地水壤环境、单一菌群应用稳定性强等特点。圆褐固氮菌与熟石灰联合使用，比各自单独使用效果更为明显，能产生协同作用，作物吸收抑制水平显著或极显著。与对照组比较，在起畦、半水淹、长期水淹三种环境中，作物体内铅的含量分别减少81.6%、63.0%和67.2%；镉分别减少45.4%、40.0%和48.9%，方差分析均具有显著性。汞的脱毒效果较好，其变化受到不同水环境影响。实验和应用情况表明，本方法能有效地限制湿地水壤环境中重金属污染物的频繁迁移，减少水系二次污染，同时，本研究成果及总结的简便操作方案，对新型无公害蔬菜的种植有较大的应用、推广与经济价值。
The Biochemical Detoxification of Heavy Metals and its Application to the Water-soil Environment in the Agricultural Wetlands of the Pearl River Delta, China
Yang Guo, Junhong Wu, Sisi Yu
Advisor: Huifang Zhou, Yongshan Su
Foshan No.2 High School in Guangdong Pr. China.
The conventional remediation methods for the direct removal of heavy metals from the water-soil environments were discarded. The adsorption and desorption property and the bioavailability of heavy metals in the wetlands were concentrated, and then the novel, feasible way to the detoxification of heavy metal were aimed for environmental protection. Pb, Cd and Hg were selected as the model heavy metals in the experiments. The changes of the contents of heavy metals in vegetables were examined in order to trace and show the changes of heavy metals in the soils. The experiments were carried out with the synergic methods of microbes and acid-base buffering. The results showed that Azotobacter chroococcum(A.ch) was the dominant target microbe, and be adapted to the environment of the wetlands in the Pearl River Delta. There were the cooperation effects of A. ch and the white lime, which might lead to the low uptake of crops for heavy metals. Compared with the control experiments, the contents of Pb in the crops decreased 81.6%, 63.0% and 67.2% under the ridged, half flooded and long-term flooded farmlands respectively, and those of Cd in the crops decreased 45.4%, 40.0% and 48.9%. Hg was the effect of different environments. It can be seen that the synergic application could inhibit the frequent transport of heavy metals in the wetlands effectively. Thus, the work might provide a new sight for the planting of the pollution-free vegetables, which might be worthy of the larger application and spread with high economical values.
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