燃煤电厂烟气中汞控制技术研究

介绍了溶解法、吸附法、化学法和鳌合法等4种燃煤电厂烟气脱汞技术。从机理上分析了烟气脱汞技术的工艺过程,对脱汞技术的进一步开发和工业化进程具有促进作用。     

含汞废弃荧光灯管处理现状及分析

废弃荧光灯管中含有金属汞,属于《国家危险废物名录》中的HW29含汞废物类,随意处置会破坏环境,危害人类健康,因此必须采取合理的方法对其进行处理。综合比较后发现资源化、无害化回收金属汞是最佳的处理方法。部分发达国家通过法律和技术手段的加强实现了对废弃荧光灯管的无害化回收处理,但我国在这方面的工作尚且不足,主要存在着灯管收集难、处理成本高等问题。因此,我国需要借鉴国外的管理经验,出台有效的法规措施,同时需要不断完善处理技术和大型工程建设。在我国节能减排和环境保护形势日益严峻的大环境下,辅之以合理的管理体制和技术手段,才能实现社会效益和经济效益双赢的局面。     

Change of magnetic properties due to fluctuations of hydrocarbon contaminated groundwater in unconsolidated sediments

Sediments affected by fluctuations of hydrocarbon contaminated groundwater were studied at a former military site. Due to remediation, groundwater table fluctuation (GWTF) extends over approximately one meter. Three cores were collected, penetrating through the GWTF zone. Magnetic parameters, sediment properties and hydrocarbon content were measured. We discovered that magnetic concentration parameters increased towards the top of the GWTF zone. Magnetite is responsible for this enhancement; rock magnetic parameters indicate that the newly formed magnetite is in a single domain rather than a superparamagnetic state. The presence of hydrocarbons is apparently essential for magnetite to form, as there is clearly less magnetic enhancement in the core, which is outside of the strongly contaminated area. From our results we conclude that the top of the fluctuation zone has the most intensive geomicrobiological activity probably responsible for magnetite formation. This finding could be relevant for developing methods for simply and quickly detecting oil spills.     

北京西城区雨水管道沉积物中重金属污染风险评价

采用地累积指数法、次生相与原生相分布比值法以及Hakanson潜在生态风险指数法从不同角度对雨水管道沉积物中重金属的污染风险进行了评价。地累积指数法的评价结果表明,不同重金属的污染级别为ZnCuCdCrPbNi。而次生相与原生相分布比值法以及Hakanson潜在生态风险指数法的评价结果表明,不同重金属的潜在污染效应关系和潜在生态危害系数大致排序均为CdCuZnPbNiCr。     

冷原子荧光法测定汞标准物质的两种定容方法比较

应用ZYG-Ⅱ型智能荧光测汞仪测定汞标准物质浓度,通过用固定液（将0．5g重铬酸钾溶于950mL水中,再加50mL的HNO3）定容与用3％的HNO3定容所测得的结果进行比较,结果表明,用固定液定容,比用3％的HNO3定容,其测得的结果与保证值之间的相对偏差要小。     

Critical analysis of the waste management performance of two uranium production units in Brazil--part II: Caetite production center

This paper discusses the environmental waste management of the Heap-Leach Uranium Production Facility of Caetité located in a semi-arid region in Brazil. A comparison is made with the first uranium production site of the country located in Poços de Caldas. It is demonstrated that differences in the operational process along with different environmental conditions can lead to different impacts. In the present case groundwater is the potential most sensitive environmental medium despite the well-established consensus in the literature that radon and aerosol emissions may turn-out to be the most relevant environmental aspects of an installation located at this type of region. Most of the ²²⁶Ra content in the ore remains in the leached ore that is deposited with the waste rock. A lack in appropriate prediction of the hydrological balance has been causing unanticipated emissions of liquid effluents into the environment. Chemical treatment of this effluent may be needed. Contamination of groundwater in the short term by the waste ponds is not to be expected but it can be a relevant issue in the long term. As a consequence, careful closure schemes will need to be put in place. Finally, the overall costs with remediation in the Caetité production center are lower than those observed at the Poços de Caldas mining site.     

A summary of total mercury concentrations in flora and fauna near common contaminant sources in the Gulf of Mexico

Total mercury concentrations are summarized for environmental media and biota collected from near-coastal areas, several impacted by contaminant sources common to the Gulf of Mexico. Water, sediment, fish, blue crabs, oysters, clams, mussels, periphyton and seagrasses were collected during 1993–2002 from targeted areas affected by point and non-point source contaminants. Mean concentrations in water and sediment were 0.02 (±1 standard deviation = 0.06) μg l⁻¹ and 96.3 (230.8) ng g⁻¹ dry wt, respectively. Mean total mercury concentrations in fish, blue crabs, brackish clams and mussels were significantly greater than those in sediment, seagrass, colonized periphyton and oysters. Concentrations (ng g⁻¹ dry wt) averaged 23.1 (two seagrass species), 220.1 (oysters), 287.8 (colonized periphyton), 604.0 (four species of freshwater mussels), 772.4 (brackish clam), 857.9 (blue crabs) and 933.1 (nine fish species). Spatial, intraspecific and interspecific variability in results limited most generalizations concerning the relative mercury contributions of different stressor types. However, concentrations were significantly greater for some biota collected from areas receiving wastewater discharges and golf course runoff (fish), agricultural runoff (oysters) and urban stormwater runoff (colonized periphyton and sediment). Marine water quality criteria and proposed sediment quality guidelines were exceeded in 1–12% of total samples. At least one seafood consumption guideline, criteria or screening value were exceeded in edible tissues of blue crabs (6% total samples) and nine fish species (8–33% total samples) but all residues were less than the US Federal Drug Administration action limit of 1.0 ppm and the few reported toxic effect concentrations available for the targeted biota.     

An assessment of metal contamination along the Irish coast using the seaweed Ascophyllum nodosum (Fucales, Phaeophyceae)

The relative abundance and variation of Cr, Co, Cd and Pb in Ascophyllum nodosum and intertidal surface sediments from six locations around the coast were assessed over six seasons. Higher Cd and Pb levels in Galway Docks and Cork Harbour were attributed to localised inputs of these metals from municipal and domestic waste, while at a reference site (Ballyconneely), high algal Cr concentrations were considered a function of geological setting rather than anthropogenic loading. Little seasonal variation was observed, with the exception of higher Co levels in plants in winter, associated with growth dynamics and increased fluvial inputs. In comparison with previously published data for metals in A. nodosum from the North Atlantic, with the exception of localised hot spots, the Irish coastline is still a relatively pristine environment. A. nodosum may be successfully and easily used as a biomonitor of metal contamination in coastal waters.     

The impact of eutrophication on the biogeochemical cycling of mercury species in a reservoir: a case study from Hongfeng Reservoir, Guizhou, China

The mercury distribution and speciation in the water column were investigated from November 2003 to September 2004. The distribution and concentrations of total mercury (THg) and particulate mercury (PHg) showed that algae had a large capacity to bind mercury in late spring (e.g. in May). It is shown that dissolved gaseous mercury (DGM) concentrations may also be affected by algae activities. The MeHg profile in the water column at a highly eutrophied site in Hongfeng Reservoir demonstrated that most of the MeHg was produced in the hypolimnion, whereas the MeHg profile pattern at another site with less eutrophication indicated that MeHg in water was largely ascribed to release from sediment. In September, the outflow of the reservoir was enriched with MeHg, which was 5.5 times higher than that in the inflows. The discharge of MeHg-concentrated water from the anoxic hypolimnion in the reservoir may pose a risk to downstream fauna.     

Essential versus potentially toxic dietary substances: a seasonal comparison of essential fatty acids and methyl mercury concentrations in the planktonic food web

We investigated seasonal variability of essential fatty acids (EFA) and methyl mercury (MeHg) concentrations in four size categories of planktonic organisms in two coastal lakes. MeHg concentrations increased significantly with increasing plankton size and were independent of plankton taxonomy. However, total EFA increased from seston to mesozooplankton, but decreased in the cladoceran-dominated macrozooplankton size-class. Analysis of EFA patterns revealed that linoleic, alpha-linolenic, arachidonic, and eicosapentaenoic acids increased with increasing zooplankton size, but docosahexaenoic acid (DHA) in the cladoceran-dominated macrozooplankton was generally lower than in seston. This consistent pattern demonstrates that cladocerans, although bioaccumulating MeHg, convey less DHA than similar-sized copepods to their consumers. It is thus evident that fish consuming cladocerans have restricted access to DHA, yet unrestricted dietary access to MeHg. Thus, the structure of planktonic food webs clearly affects the composition of EFA and regulates dietary supply of these essential nutrients, while MeHg bioaccumulates with increasing zooplankton size.