东莞市耕地环境质量的压力-状态-响应分析与评价

基于"压力-状态-响应"模型建立了耕地环境质量评价框架及其指标体系。以东莞市为研究样区,采集182个耕地土壤样品,测定其重金属含量,结合东莞统计年鉴中的社会经济数据,对东莞市耕地环境质量进行评价,并通过协调度模型对其稳定性进行分析。结果表明:东莞市28.2%的耕地处于良好和较好水平,主要分布在北部河网平原区,该区作为供水工程水源地,环境受到严格保护;56.1%的耕地处于警戒水平,处于较差水平的耕地占总面积的15.7%,没有耕地处于极差水平。主要影响因素为经济发展和工业"三废"排放压力、耕地自然性状及其耕作管理状态、农药化肥过量施用等不合理的农户响应措施。压力、状态、响应指数协调度较低的乡镇有南城、望牛墩、沙田、长安,其耕地环境质量不稳定,是耕地环境质量管控的重点区域。

Bacteria-Enhanced Remediation of Electronic-Waste Polluted Farmland Soil

Qingyuan is one of the biggest electronic waste(e-waste) dismantling areas in China. Over 20-year operations of individual e-waste workshops there have resulted in severe pollution of the surrounding soils by Cd, Cu and Pb. Remediation of e-waste polluted soils has drawn scientific and public attentions. In our previous study, four strains of metal tolerant bacteria were identified from the soils contaminated by e-wastes in Qingyuan, using colony morphology analysis, scanning electron microscope and 16S rDNA technology. They were Sporosarcina aquimarina(HS-01), Sporosarcina saromensis(JH-02), Bacillus megaterium(YB-03) and Bacillus methylotrophicus(JY-04). Here we used these four strains and a non-contaminated ecotype of plant Sedum alfredii to test their potential for remediating soils polluted by Cd, Cu and Pb under greenhouse conditions. Results show that the shoots of S. alfredii accumulated the highest amount of heavy metals in the presence of JH-02 bacteria, followed by JY-04 bacteria. Bacteria JH-02 and JY-04 exhibited better performance in mobilizing heavy metals, and exchangeable metal fraction was significantly higher in the JH-02 and JY-04 treatments than in other bacterial treatments(P<0.05). Our present study suggest that the bacteria JH-02 and JY-04 may be able to enhance the extraction of soil heavy metals by S. alfredii, and thus have a potential to be applied to the field.