Heavy metals and soil microbes

The discovery in the early 1980s that soil microorganisms, and in particular the symbiotic bacteria Rhizobium, were highly sensitive to heavy metals initiated a new line of research. This has given us important insights into a range of topics: ecotoxicology, bioavailability of heavy metals, the role of soil biodiversity, and the existence of ‘keystone’ organisms. Concurrently, and particularly in Europe, the research led to new approaches to the protection of soils from pollution that take into account the many effects on soil microorganisms. To date these key findings have largely been ignored in the USA, although our results caused considerable controversy there. In the past decade there have been many advances in the ecotoxicological assessment of metals and their effects on soil organisms but major gaps in knowledge and theory remain with regard to how microorganisms are exposed and respond to metals in soils. In this brief review we emphasise the need for long-term experiments and basic research to forge this understanding and improve environmental protection policies.     

人工湿地底泥中特征重金属的空间分布及生态风险评价

采集武河湿地沉积物,采用四酸消解法(HCI-HNO3-HF-HCIO4)对样品进行处理,测定武河湿地沉积物中6种重金属(As、Cd、Cu、Hg、Pb和Zn)的含量,分析其空间分布特征,并采用内梅罗综合污染指数法、潜在生态危害指数法和ERL/ERM评价法评价重金属的环境风险。结果表明,武河湿地表层沉积物中重金属含量大多高于环境背景值,空间分布差异性较小。内梅罗综合污染指数按由大到小依次为Hg、Cd、As,Zn、Cu、Pb,Hg的内梅罗综合污染指数最大为3.74,综合污染程度最为严重。潜在生态风险评价表明,湿地沉积物中潜在生态危害指数(RI)为743.91,属Ⅴ极强生态危害。ERL/ERM评价结果显示,湿地沉积物中Cu、Hg含量高于ERM值,对水生态系统有很强毒性;As、Zn的含量介于ERL和ERM之间,可能会对水域生物产生一定的毒性。     

湖南矿区县域耕地重金属污染空间特征及潜在风险评价

运用单因子指数法和潜在生态危害指数法,借助GIS技术,对研究区耕地土壤Cd、Cr、Pb、As和Hg的污染状况进行了评价和预警。单因子指数评价结果显示,研究区各重金属的污染指数大小依次为CdAsHgCrPb;潜在生态风险评价结果显示,研究区各重金属单项潜在生态风险系数大小依次为:CdHgAsPbCr,其中八团乡和高垅镇的Cd污染风险相对较大;研究区耕地土壤重金属的综合潜在生态风险程度中等,各个乡镇的综合潜在生态风险指数从大到小依次为:高垅镇八团乡潞水镇思聪乡平水镇严塘镇秩堂镇腰陂镇火田镇洣江乡虎踞镇下东乡;综合潜在生态风险预警结果显示,巨警区主要集中在高垅镇、八团乡、潞水镇、平水镇、思聪乡以及桃坑乡。研究结果可为研究区域的重金属污染综合防控和农业安全生产布局提供科学依据。     

苦参碱金属配合物的合成及抑菌活性研究

为了明确苦参碱金属配合物的抑菌活性,于无水乙醇中合成2种配合物,采用元素分析、红外光谱分析、差热热重同步分析、单晶衍射分析对配合物的结构进行表征,确定组成及结构。采用菌丝生长速率法测定配体及配合物对番茄灰霉病菌、小麦赤霉病菌、马铃薯晚疫病菌的抑菌活性。结果表明,合成的配合物经结构表征后,确定其结构为1分子苦参碱与1分子金属离子配位。药剂质量浓度为800mg/L时,苦参碱金属配合物的抑菌活性均高于配体,尤其锌配合物对番茄灰霉病菌的抑制率提高近7.1倍,铁配合物对小麦赤霉病菌以及锌配合物对马铃薯晚疫病菌的抑菌活性最强,其抑制率分别为79.8%、95.2%。苦参碱能与铁、锌金属离子形成金属配合物,且配合物的抑菌活性相对于配体有不同程度的提高。     

Potentially bioavailable metals in sediment from a tropical polymictic environment—Rio Grande Reservoir,Brazil

Background, aim and scope  Although many recent studies have focused on sediment potential toxicity, few of them were performed in tropical shallow aquatic environments. Those places can suffer short-time variations, especially due to water column circulations generated by changes in temperature and wind. Rio Grande reservoir is such an example; aside from that, it suffers various anthropogenic impacts, despite its multiple uses. Materials and methods  This work presents the first screening step for understanding sediment quality from Rio Grande reservoir by comparing metal content using three different sediment quality guidelines. We also aimed at verifying any possible spatial heterogeneity. Results and discussion  We found spatial heterogeneity varying according to the specific metal. Results showed a tendency for metals to remain as insoluble as metal sulfide (potentially not bioavailable), since sulfide was in excess and sediment physical–chemical characteristics contribute to sulfide maintenance (low redox potential, neutral pH, low dissolved oxygen, and high organic matter content). On the other hand, metal concentrations were much higher than suggested by Canadian guidelines and regional background values, especially Cu, which raises the risk of metal remobilization in cases of water circulation. Further study steps include the temporal evaluation of AVS/SEM, a battery of bioassays and the characterization of organic compounds.     

基于快速成型的金属树脂模具快速制造技术

介绍了适合于多品种、小批量农业机械生产的基于快速成型的金属树脂模具快速制造技术,包括金属树脂模具材料的研究,金属树脂模具快速制造过程、关键工序分析以及快速制模方法的特点。     

金属纤维长度对胶合板性能的影响

为了赋予木基复合材料电磁屏蔽功能,在脲醛树脂胶中加入不锈钢纤维(SF)和黄铜纤维(CF)导电单元,制备三层结构的落叶松复合胶合板,研究不同长度的导电单元以及涂胶量对木基复合材料电磁屏蔽性能(SE)和胶合强度(ST)的影响。结果表明,胶合强度均达到或超过国家标准。涂胶量增大对电磁屏蔽效能有不利影响。在施加不锈钢纤维的条件下,胶合板的电磁屏蔽效能为13．40～21．37dB,电磁屏蔽模型和胶合强度模型均显著。在施加不锈钢纤维的条件下,电磁屏蔽效能为15．61～35．01dB,电磁屏蔽模型均显著,胶合强度模型不显著。金属纤维长度的增加可以使胶层中不锈钢纤维的搭接率增加,有利于电磁屏蔽效能的增加。     

苍溪县国际金融组织贷款项目欠款情况调查

国际金融组织贷款项目,通过＂引资＂和＂引智＂等多种渠道,极大地支持了地方经济发展,目前各类国际金融组织贷款项目已陆续进入还本付息高峰期,但地方发展和改革的压力重,财力拮据,如何做好国际金融组织贷款项目欠款偿还工作,是一个值得研究的课题。     

准确把握科技事业单位 特点进一步完善财政项目绩效评价

财政项目费用是科技事业发展的重要资金来源,绩效评价是对资金利用效果的评判手段。通过对项目绩效管理内涵的正确认识,分析了目前项目绩效评价的局限性和片面性。从建立科学的评价体系、推行项目动态管理、完善绩效评价内容、建立责任激励机制以及改进相关政策等方面,提出了加强财政项目绩效管理的合理化建议。     

漆酚金属盐高分子复合催化剂催化酯化反应

探讨了漆酚金属盐高分子复合试剂催化酯化反应的情况,首先以乙酸和丁醇为反应体系,筛选了最佳催化剂,实验表明,Ｆｅ、Ａｌ、Ｔｉ、Ｓｎ等的金属盐与漆酚树脂的复合度剂均能催化酯化２,其中,漆酚Ｆｅ＾３＋和Ａｌ＾３＋盐的复合试剂催化酯化活性最好,重复使用８次后转化率仍为９２％。此外,该催化剂还能催化乙酸乙酯、乙酸丙酯、忆知心是等一系列有机酯的合成,转化率为８７－９７％,且能重复使用。