酸雨的大气物理化学机理

1.输送过程中的化学转化对北美洲雨水样品的分析表明:雨水的酸度在很大程度上取决于它的硫酸盐和硝酸盐离子浓度,因此本文将着重讨论这两种污染物的形成过程。虽然,大气中有少量的硫酸盐和硝酸盐是被直接排放出来的,但据认为,降雨中这两种盐类的主要来源是硫氧化物和氮氧化物的进一步氧化。然而在燃油发电厂和炼油厂附近,硫酸盐的直接排放量还是较大的。由上述情况可以看出,了解排放点和接受点之间排     

24、用电化学和紫外检测的高压液相色谱法测定卤代苯胺及有关化合物

卤代苯胺可以从各种渠道包括农药、除莠剂、杀菌剂的代谢作用,工业废料和硝基取代芳香化合物的还原而进入环境中。由于苯胺类化合物有毒所以要求在环境中监测。以前用气相色谱法,需要进行衍生化;而且某些被卤代的代谢物还不能被分离。本文研究的高压液相色谱法可在无衍生化步骤的情况下进行分离,并检测出亚毫微克量的物质。这些化合物是用商品c-18键合相柱分离的,并用价廉的电化学检定器检测至亚毫微克量级。同时还研究了快速但灵敏度很低的紫外线方法。列举了各种化合物的色谱图和灵敏度数据。讨论了电化学检定的应用和限度。     

Biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and pure cultures of imperfect and lignolitic fungi

The biodegradation of aliphatic and aromatic hydrocarbons by natural soil microflora and seven fungi species, including imperfect strains and higher level lignolitic species, is compared in a 90-day laboratory experiment using a natural, not-fertilized soil contaminated with 10% crude oil. The natural microbial soil assemblage isolated from an urban forest area was unable to significantly degrade crude oil, whereas pure fungi cultures effectively reduced the residues by 26-35% in 90 days. Normal alkanes were almost completely degraded in the first 15 days, whereas aromatic compounds (phenanthrene and methylphenanthrenes) exhibited slower kinetics. Aspergillus terreus and Fusarium solani, isolated from oil-polluted areas, produced the more efficient attack of aliphatic and aromatic hydrocarbons, respectively. Overall, imperfect fungi isolated from polluted soils showed a somewhat higher efficiency, but the performance of unadapted, indigenous, lignolitic fungi was comparable, and all three species, Pleurotus ostreatus, Trametes villosus and Coriolopsis rigida, effectively degraded aliphatic and aromatic components. The simultaneous, multivariate analysis of 22 parameters allowed the elucidation of a clear reactivity trend of the oil components during biodegradation: lower molecular weight n-alkanes > phenanthrene > 3-2-methylphenanthrenes > intermediate chain length n-alkanes > longer chain length n-alkanes > isoprenoids approximately 9-1-methylphenanthrenes. Irrespective of the individual degrading capacities, all fungi species tested seem to follow this decomposition sequence.     

Scots pine needle surfaces on radial transects across the north boreal area of Finnish Lapland and the Kola Peninsula of Russia

To gain an understanding of the characteristics of the needle surfaces of naturally regenerated Scots pine (Pinus sylvestris L.) and their geographical distribution, eight physicochemical variables were investigated within the north boreal forest area. The visibly undamaged needles were collected in autumn 1990 from 114 plots (3-5 pines per plot) along radial transects from the Monchegorsk and Nikel smelters, emitting SO2 and heavy metals, on the Kola Peninsula, Russia, to Finnish Lapland. The needles were examined by scanning electron microscopy (SEM) and measured for surface wettability using the droplet contact angle (DCA) method. Significant geographical south-north and west-east patterns could be observed in needle surface characteristics, correlating with emissions from the smelters and to climate. Despite the slightly higher initial DCAs (61.4-87.6 degrees) towards the north, the pine needle surfaces of the northernmost transects exhibited higher annual needle wettability change (ANWC) and wax erosion rate (AWER), expressed as the reduction in DCAs and epistomatal wax tube distribution (WTD) during one year, respectively, but a lower occurrence of particles and fungal hyphae than those of more southern transects. The higher ANWC was related to higher atmospheric SO2 concentration, and to the lower long-term temperature sum, but not clearly to annual precipitation. In the Monchegorsk smelter area, the current needles exhibited, on average, a 15% higher WTD and seven degree larger DCA, resulting in more hydrophobic needle surfaces than in Finnish Lapland, but during their first year, both the AWER and ANWC, were greatly increased. In Finnish Lapland, 30%, of all the epistomatal wax tubes disappeared from the needle surface during the first year, the value being 70% for the pines located 8 km from the smelter. The mineral composition of the particles deposited on the needle surfaces mirrored that of the minerals being produced by the smelters (e.g. FexSx, CuFeS2, NixSx, FexOx). Stomatal densities were in the range of 71.1-141.7 stomata mm(-2). The lower densities of stomata on needles close to the smelters correlated with reduced number of needle age classes of the pines, higher dry weights, higher pollutant accumulation and lower Mn and Zn concentrations in the needles. The AWER and ANWC were able to indicate the most seriously deteriorated needle surfaces on a regional scale, e.g. including the surroundings of both smelters, although the plot-specific relationships between 'needle surface variables' and 'pollution variables' were generally weak. The present study showed that the exposure of pine needles to the combined effects of ambient pollutants and harsh climate led to a deterioration in the physicochemical characteristics of the epicuticular wax, which may have serious ecophysiological consequences in the long term.     

The effect of papermill wastewater and organic amendments of sodium accumulation by potted cottonwoods

In this experiment, the impacts of pulp mill effluent irrigation, Fraser cottonwood (Populus deltoides 'Fraser') seedlings, and pulp sludge and manure soil amendments on sodium accumulation and distribution in the soil profile were evaluated during a 6 month greenhouse study. Sludge soil amendments and wastewater irrigation did not reduce stem biomass production of the cottonwood. Increased stem biomass production associated with manure soil amendments resulted in greater total uptake of sodium into stem material. This uptake was 0.002% of wastewater sodium inputs. In containers with seedlings, sodium concentrations were less in the surface horizon and more in the lower horizons than in containers with no seedlings. Infiltration rates and total sodium accumulation in the soil profile were not affected by the presence of Fraser cottonwood or the application of sludge or manure amendments to soil.     

Cationic surfactant as a sensitizer for the spectrophotometric determination of hydrogen sulphide in air and evaluation of a new absorbing medium containing triethanolamine-zinc acetate-sodium hydroxide

An extractive spectrophotometric method for the determination of trace amounts of hydrogen sulphide after fixing the gas in triethanolamine (TEA)-zinc acetate-sodium hydroxide solution is described. The method is based on the reaction of iodate with hydrogen sulphide in the presence of acid and excess chloride ion leading to the formation of ICl2- species which is used to iodinate 2',7'-dichlorofluorescein to form 2',7'-dichloro-4',5'-diiodofluorescein. The iodinated product formed is extracted into an organic solvent and sensitized by equilibrating with a cationic surfactant, cetrimide, in the presence of acetate buffer (pH 5.9 +/- 0.1). The colour system obeys Beer's law over the range 0-1 microg of hydrogen sulphide and the relative standard deviation is 2.4% for 10 determinations at 0.75 microg of hydrogen sulphide. The effect of interfering gases on the determination is discussed. The proposed absorbing solution has been evaluated using a hydrogen sulphide permeation device. This absorbing solution has an absorption efficiency of > 93% at a flow rate of 1.5 litre min(-1) for a sampling period of 2 h. The fixed H2S is stable for 40 days. The method has been applied to determine residual H2S levels in a laboratory fume hood and in the vicinity of sewage pumping station. The method can be used to determine as little as 0.05 microg of hydrogen sulphide.     

Patterns of soil copper contamination and temporal changes in vegetation in the vicinity of a copper rod rolling factory

Patterns of soil copper contamination have been examined in the vicinity of a copper rod rolling plant in Prescot, Merseyside, UK. The site, established in 1975, was found to possess clear patterns of soil copper contamination, with the highest levels of HNO3 and water-extractable fractions encountered in the factory grounds adjacent to the location of the furnace chimney. The majority of the copper had accumulated in the upper soil horizons. The site is surrounded by planted lawns, established at different times after the commissioning of the plant. The species composition of the extant grassland communities, found at sites with differing soil copper levels, was compared to the composition of the original seed mixtures sown at each of ten sites. These surveys clearly showed that different levels of soil copper contamination had produced significant changes in grassland composition with time. At the most polluted site, copper tolerant Agrostis capillaris clones were the main grasses present only two years after the area was sown with a four-species mixture of non-tolerant grass seed. Lolium perenne possessed extreme sensitivity to copper. A number of dicotyledonous species, normally considered sensitive to elevated copper levels, were found to be unaffected where such conditions had arisen after plants had established from seed.     

Persistent organochlorine residues in soils from tropical and sub-tropical Asian countries

Soil samples from paddy fields, uplands, and urban areas (gardens and roadsides) collected from Vietnam, Thailand, and Taiwan were analysed to determine the residual levels of persistent organochlorine compounds such as DDTs, HCHs, and PCBs. DDT concentration in soil samples from Vietnam were found to be highest, with a mean value of 110 ng g(-1), and were followed by those in Taiwanese soils with a mean value of 20 ng g(-1). HCH concentrations were highest in soil samples from Vietnam (a mean value of 4.8 ng g(-1)) and were followed by those from Taiwan (a mean value of 1.4 ng g(-1)). Concentrations of PCBs were found to be highest in Taiwanese soil samples, with a mean of 95 ng g(-1). Interestingly, relatively high concentrations of PCBs in rural cultivated-soil samples from Vietnam were recorded with a mean value of 25 ng g(-1), probably suggesting PCB release from different kinds of weapons used during the Second Indochina war. The lowest concentrations of DDTs, HCHs, and PCBs were obtained in soil samples from Thailand, with mean values of 8.3 ng g(-1), 0.4 ng g(-1), and 2.7 ng g(-1), respectively.     

Emergency centers in Israel: A small community organizes to cope with war related crises*

This paper focuses on community-wide emergencies caused by war-related events in Lebanon at the beginning of June 1982. Mobilization for the "Peace for Galilee" campaign began on Friday, 4th June. Overnight, families were disrupted, husbands and sons were in danger, and within 24 hours there were notifications of casualities and deaths. Families in crisis became a widespread phenomenon. In Herzlia, as in many other communities, a new service - the Emergency Center - emerged under the auspices of the Ministry of Labor and Social Affairs and the Municipality. The authors describe this process of getting organized, the populations served, how the Center was staffed, the role of citizen volunteers, and the types of interventions used to help vulnerable families as well as soldiers home on leave. Stress is placed on the unique type of short-term co-operation achieved between social workers of the local Department of Social Welfare, the staff of the Department of Community Services (especially its Volunteer Bureau), the local liason officer of the Israel Defence Force, the municipal government, and public-spirited volunteers. Mention is made of conditions which made possible the activation of such a service within hours, of the Center's capacity to serve all segments of the population, and of how it was deactivated within a few weeks when the emergency ended. On the basis of lessons learned from this experience, the paper ends with a number of specific recommendations. The authors hope that such innovative forms of crisis-intervention will become part of the helping technology widely available at the community level in future years.