A GIS raster technique to optimise contaminated soil removal

A geographic information system (GIS) raster technique has been developed and used interactively with remediation designers to evaluate the optimum extent of excavating soil contaminated by chlorinated solvents. The technique and the results of its application are presented. The site was a former chemical storage plant for acids and solvents. Two distinct solvent plumes were detected within the ground using a photo-ionisation detector. The solvents were found to be dissolved in the groundwater and migrating in the general direction of groundwater flow. A remediation strategy was proposed involving the localised excavation of contamination ‘hot spots’ followed by the implementation of a groundwater remediation system. A number of excavation options were discussed and the GIS raster technique was developed to evaluate these options in terms of contaminant removed and excavation cost.

The plumes were initially mapped using a triangular irregular network (TIN). These TIN models were rasterised to produce a regular grid of rectangular cells, each cell having a value relating to the concentration of contaminant at that spatial point. The proposed excavation zones were then overlaid on to the raster models as masks. The relationship between the value of contaminant concentration of cells within the mask (or excavation zone) and the total value of contaminant concentration of cells within the solvent plume was used to determine the efficiency of the excavation.

The excavation options were compared taking into account the percentage of the contaminant plume removed, the excavation area (soil volumes) and related costs. Once the GIS raster technique had been developed, it proved very quick to rerun the analysis for the other excavation zones. The optimum excavation zone, based upon cost and contaminant recovery, was found for the site. The technique helped by targeting the worst area of contamination and provided the client with a cost-benefit analysis of the different remediation options.     

微藻基因工程在高价值化合物生产上的应用

微藻在生产蛋白质、油脂、色素等方面具有作为细胞工厂的潜力,在解决传统生物量生产和市场未来的一些局限性方面发挥着推进作用.基因工程促进了微藻的改良,推动了微藻的产业化进程.本文综述了近年来微藻基因工程的研究进展以及基因工程在微藻生产生物燃料、医药等方面的应用.本文能为基因工程技术在微藻中的研究及应用提供思路,从而使微藻以...     

Characterization and source apportionment of volatile organic compounds in urban and suburban Tianjin,China

Tianjin is the third largest megacity and the fastest growth area in China, and consequently faces the problems of surface ozone and haze episodes. This study measures and characterizes volatile organic compounds(VOCs), which are ozone precursors, to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin,China during the Ha Chi(Haze in China) summer campaign in 2009. A total of 107 species of ambient VOCs were detected,and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv, respectively. Of those, 51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization. The identified sources of VOCs were significantly related to vehicular activities, which specifically contributed 60% to urban and 42% to suburban VOCs loadings in Tianjin. Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas, although the contribution of industry in the suburban area(36%) was much higher than that at the urban area(16%). We conclude that controlling vehicle emissions should be a top priority for VOC reduction, and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life, especially in suburban areas.     

海产腹足类性畸变现象的形态特征

本文选取我国东南沿海的重要港口海口、北海、湛江、汕头和厦门港等作为海产腹足类性畸变现象的现场调查区，结果发现有11种海产腹足类存在性畸变。文中对分布广泛、易采集、性畸变现象普遍的疣荔枝螺的性畸变特征的解剖观察结果进行了详细的描述，同时对其他几种海产腹足类性畸变特性作了对比。根据研究结果将疣荔枝螺性畸变雌体的阴茎和输精管的畸变程度划分为5个阶段。     

Enzyme leach anomalies associated with deep Mississippi Valley-type zinc ore bodies at the Elmwood Mine, Tennessee

Deeply buried Mississippi Valley-type deposits that have been or are currently being mined in North America were initially discovered by drilling. Conventional geochemical methods are ineffective for detecting these ‘blind' deposits when they occur deep within sequences of stable-platform carbonates and shales. The ‘enzyme' leach is a selective analytical technique for determining trace elements associated with amorphous Mn oxide coatings in soils. In many areas of the world, the enzyme leach method is useful for detecting low-level geochemical anomalies in soils, which are associated with blind mineral deposits. Enzyme leach analysis of soils, collected at the Elmwood Mine, Tennessee, revealed high-contrast anomalies over ore bodies 370 m below the surface. In areas where the soils are in chemical equilibrium, ‘combination' anomalies occur over Zn ore bodies. These are characterized by asymmetrical halogen halos which occur around a halogen ‘central low'. Commodity metals (Zn and Pb) and trace elements associated with the ore (Cd, Ba, and Mn) form apical anomalies, which occur over the ore bodies and within the halogen halo. Under most circumstances, agricultural practices do not affect enzyme leach results. However, agricultural activity in central Tennessee appears to have altered the proportion of amorphous Mn oxides in the soils in some locations. Where the MnO₂-form equilibrium of the soil has been disturbed, enzyme leach data are erratic. In the one instance where this was encountered, ratioing the data to Mn reveals anomalies which bracket the blind ore bodies.     

挥发性有机污染物标准物质使用的短期稳定性评价

为对挥发性有机物标准物质的短期稳定性进行评价,选取美国ChemService公司生产的LVOC-1RPM(甲醇中54种挥发性有机污染物混合标准物质)和SS-524RPM(甲醇中4-溴氟苯和1,2-二氯苯-d4混合标准物质),将其开封后转移至2 mL带聚四氟乙烯衬盖的棕色螺口样品瓶中再密封,于-18℃避光贮存,采用气相色谱-质谱法测试各组分量值随贮存时间的变化。结果表明,在65 d内,两种标准物质各组分量值测量的标准偏差在12～60 mg/L范围内,最大相对标准偏差为2.97%(n=5),测量结果的相对不确定度小于5.39%。在置信度为95%时,χ2-检验和不确定度评定结果表明,评价方法满足标准物质稳定性检验的精密度和准确度要求;标准物质各组分量值在(2000±128)mg/L范围内时,测量的偏差不显著。在不超过标准物质的有效期内,开封后再密封的LVOC-1RPM标准物质至多可保存65 d,而SS-524RPM标准物质至少可保存65 d。     

越冬前后海马齿脂肪酸和挥发性有机物组成和变化特征

海马齿是一种热带和亚热带盐生植物, 既是传统野生菜蔬, 也在海岸带生态修复中发挥重要作用。北移种植海马齿进行生态修复时, 越冬低温的影响是成功与否的首要关注问题, 其机制尚待解明。脂肪酸在生物耐受低温中发挥作用, 挥发性有机物与脂肪酸代谢关系密切。本研究利用海湾环境中生态修复浮床上的海马齿样品, 重点解析北移种植环境下, 海马齿植株不同部位受越冬影响前后的脂肪酸和挥发性有机物的组成、差异及变化特征。结果显示, 海马齿的花、叶、茎和根样本中, 共检出14种脂肪酸, 根中的脂肪酸种类数相对最多; 多不饱和脂肪酸在花和叶中的含量(平均分别为56.46%和60.23%)总体大于茎和根(平均分别为41.56%和44.45%)。茎、叶中共检出86种挥发性有机物, 蘑菇醇为优势种类。越冬后脂肪酸和挥发性有机物种类数量显著降低, 多不饱和脂肪酸比例在冻伤植株中显著升高; 就植株脂质营养指数而言, 耐受越冬低温的植株其脂质营养品质提高。越冬造成海马齿两类化合物发生显著变化, 其中C18脂肪酸代谢响应有重要贡献, C18: 3(n-3)和蘑菇醇分别是脂肪酸与挥发性物质中最为重要的两个代谢产物, 可能与抗冻应激有密切关系。本研究为推广海马齿种植以构建可持续近海生态修复体系提供了参考。     

湘西下寒武统含铀磷块岩中钛铀矿和晶质铀矿的发现及其成因分析

对湘西下寒武统牛蹄塘组黑色页岩系中的含铀多金属磷块岩,笔者通过α径迹法示踪,先后采用电子探针、扫描电镜及透射电镜进行成分和结构分析,首次在其中发现了微晶状的晶质铀矿、斜方钛铀矿和钛铀矿。这3种铀矿物密切共生,也与钼、镍、铅、锌、铜、钒、铁等的硫化物共生,主要赋存于多金属磷块岩的雏晶石墨中,与碳的关系密切;其次也赋存于石英和先期形成的碳硫钼矿碎片中。斜方钛铀矿呈长柱状,钛铀矿呈短柱状和粒状,晶质铀矿多呈它形粒状,少数呈八边形自形、半自形晶。矿物粒径多在1~5μm,集合体可达10~20μm。进一步的成因研究表明,钛铀矿和晶质铀矿由高温铀氢化合物海底气相喷出凝聚所形成。     

Preparation and Structural Investigation of CuCl2 Graphite Intercalation Compounds

Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.