首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Assessment of the pollution level of soils and vegetation by fluorine and heavy metals and also of the state of the soil microflora in the impact zone of Kandalaksha aluminium factory is discussed. The significant pollution of natural media by fluorine in the basin of the White Sea is established. Concentration of the total fluorine in the organogenic horizon of the Al-Fe-humus podzol soil at a distance of 20 km in the northern direction from the source of emission exceeds the background level by a factor of 3. In the epicentre of emission the amount of total fluorine in the soil exceeds the background level by a factor of 7-8 (Tolerable Amount: 4-5-fold). It is noted that the soil becomes more alkaline under the influence of fluorine and the increased content of chromium along the soil profile exceeds PC by a factor of 3 in the vicinity of the factory. The differences in the dimensions of bacterial and fungi biomass along the gradient of pollution were not revealed in the impact zone. But the changes in the taxonomic structure of fungi and in the level of their domination along the gradient of pollution were estimated. Floristic composition of the soil algae is represented mainly by unicellular green algae with Chlamydomonas elliptica and Bracteacoccus minor predominating.  相似文献   

2.
A microarray for the detection of toxic algal species was developed in the European Union 7th Framework project MIDTAL. We initially tested all available fluorescence in situ hybridisation probes for toxic algae, which are normally designed to a length of 18 nt, and found that in most cases the signal was rather weak or all probes designed from the second half of the molecule were inaccessible in a microarray format because of secondary structure of the ribosomal RNA molecule We modified the length of the probes, the fragmentation of the rRNA, the stringency of the washing buffers and the length of the spacer molecules linking the probes to the glass surface of the microarray. Because of the secondary structure of the rRNA molecule, regions of the molecule can be difficult to access by the probes. Each of these modifications has improved probe accessibility and probe specificity to reduce false positives.  相似文献   

3.
The planning and using of open spaces in urban areas very much depend on the shading of the surrounding building structures. This article presents a method for the investigation of the sunlight and the bioclimatic conditions in dependence on the surrounding buildings. It is illustrated for typical courtyards in Berlin, Germany, as one type of open spaces. The programme HelioDat determines the shading of any spot of an open space. It gives the possible duration of direct sunlight for the selected spot for each day of the year. The sunlight conditions in the courtyards differ from one another a lot in dependence on their size the tallness of the surrounding buildings. The calculation of the PMV on the basis of the results of the programme HelioDat determine the bioclimatic situation in the discussed courtyards. Although the results of HelioDat are only one input among the weather conditions and the personal characteristics of the test-person, the bioclimatic conditions correlate very much with the sunlight conditions. In a projected building structure, the sunlight conditions vary a lot between the present situation and the two architectural alternatives. Since the bioclimatic situation is correlated to the sunlight conditions, this example demonstrates the importance for the investigation of the sunlight conditions and the bioclimate already during the planning process of buildings.  相似文献   

4.
Chen S  Cao G 《Chemosphere》2005,60(9):1308-1315
In this paper, dichromate and dichlorvos are selected as the deputies of inorganic and organic pollutants, respectively, and TiO2/beads is used as a photocatalyst. The effects of various parameters, such as the amount of the photocatalyst, H2O2 concentration, metal ions, anions, pH value, and organic compounds on the photocatalytic reduction of dichromate and photocatalytic oxidation of dichlorvos are studied. From the studies, the differences of the parameters effect on the photocatalytic degradation of organic and inorganic pollutants are obtained. The results show that the optimum amount of the photocatalyst used is 6.0 g cm(-3) for the photocatalytic reactions. With the addition of a small amount of H2O2, the photocatalytic reduction of dichromate is inhibited while the photocatalytic oxidation of dichlorvos is accelerated. With the addition of trace amounts of Fe3+ or Cu2+, both the reactions are accelerated, and with the addition of Zn2+ and Na+, no obvious effects on the reactions are observed. Acidic solution is favorable for the photocatalytic reduction of dichromate; and acidic and alkaline solutions are favorable for the photocatalytic oxidation of dichlorvos. Adding SO4(2-), the photocatalytic oxidation is accelerated and adding Cl- the reaction is inhibited; and with the addition of trace amounts of SO4(2-), Cl- and NO3-, no obvious effects on the photocatalytic reduction of dichromate are observed. With the addition of methanol and toluene, the photocatalytic reduction of dichromate is accelerated, and the photocatalytic oxidation of dichlorvos is inhibited. The possible roles of the additives on the reactions are also discussed.  相似文献   

5.
The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.  相似文献   

6.
The understanding of the global environmental multiphase distribution of persistent organic pollutants (POPs) as a result of the physico-chemical properties of the respective compounds is well established. We have analysed the results of a vertical transport of POPs from surface water to deepwater in terms of the contamination of the biota living in the respective environmental compartments. Samples were taken from the North and the South Atlantic and from the uprising water region of the continental shelf of California (Marine Sanctuary Monterey Bay and its Canyon). The contents of persistent organochlorine pesticides (DDTs, chlordanes, toxaphenes, HCHs, and HCB) in surface-living fish are compared to those in deepwater fish of the same geographic area. The deepwater biota show significantly higher burdens as compared to surface-living species of the same region. There are also indications for recycling processes of POPs of the class of organochlorine pesticides in the biophase of the abyss as well. It can be concluded that the bio- and geophase of the deep-sea may act as an ultimate global sink for persistent semivolatile contaminants in the marine environment like the soil on the continents.  相似文献   

7.
BACKGROUND, AIMS AND SCOPE: The concentration of chlorinated dibenzo-p-dioxins and dibenzofurans in many fish from the Baltic requires monitoring, since it approaches or exceeds the European Union threshold limit value of 4 pg TEQ/g wet weight of fish for human consumption. The concentrations, expressed in TEQs, are important for toxicology and regulations, but hide the concentrations of the individual congeners, which are important for other environmental sciences, source allocation, and for the detection of measurement errors. This report evaluates the results of a survey reported earlier only in the terms of the TEQ concentrations. METHODS: Principal Component Analysis (PCA) was used to reduce the dimensions of the data (17 = 7 chlorinated dibenzo-p-dioxin and 10 chlorinated dibenzofuran congeners) to three principal components. This facilitated the interpretation of the congener profiles. Slopes of the congener concentrations as a function of age of the fish were estimated by least squares regression. The results were compared with a large set of data for lake trout from Lake Ontario. RESULTS AND DISCUSSION: The congener profiles of Baltic herring are less scattered than those of sprat. The profiles of herring from the central Baltic differ from those of herring from the Gulf of Riga and both appear to be affected relatively minimally by the age of the fish. The congener profiles of herring from the western Gulf of Finland are similar to those from the central Baltic, those from middle Gulf of Finland are similar to those from the Gulf of Riga. Both seem to be more affected by age of the fish than the profiles of the first two groups. The concentrations of several pentachloro- and hexachloro-dibenzo-p-dioxins and dibenzofurans increase with the age of the fish CONCLUSION: PCA is a good technique for the evaluation of the congener profiles. The resulting loading and score plots provide a good graphic summary of the multidimensional data. Additional analyses are needed to confirm the observed profile patterns. A comparison with the results of a long-term monitoring from another area shows that the age of the fish is a more important factor than the year of capture. RECOMMENDATION AND OUTLOOK: The surveys should continue for a number of years and the results should be presented and evaluated both in terms of the TEQs as well as in terms of weight concentrations. Since the concentrations do not appear to change very much from year to year, it would be better to carry out surveys only every 3-4 years and, instead, stratify the sampling according to age and gender of the fish, and to analyze replicate extracts by replicate measurements. The inclusion of unmarked replicate samples would be a good quality assurance measure. It would be desirable to analyze additional parts of the food chain in order to understand the fate of the compounds in the ecosystem.  相似文献   

8.
电絮凝-气浮-砂滤组合工艺除氟   总被引:1,自引:0,他引:1  
为了有效去除水中的氟离子,对电絮凝-气浮-砂滤组合工艺除氟(F-)离子进行了研究。详细考察了电压、电絮凝停留时间和初始F-离子浓度等参数对除F-离子效率的影响。结果表明:当初始F-离子浓度为1.50 mg/L,停留时间为10 min,电压为15 V条件下,出水F-离子浓度为0.92 mg/L;当初始F-离子浓度为2.5 mg/L,停留时间为15 min,电压15 V条件下,出水F-离子浓度为0.98 mg/L。用Al-Ferron逐时络合比色法表征了电絮凝和气浮单元出水中铝形态随时间的变化。结果显示:电絮凝出水Ala含量随时间增加迅速降低到5%以下,电絮凝和气浮单元出水Alb含量均占到50%以上,Alc含量均随时间增加而增加。  相似文献   

9.
利用计算流体力学模拟技术,采用三维、稳态、k-ε紊流模型,结合多重参考系模型、弥散相模型及组分输运和化学反应模型,对江苏某污水处理厂水解酸化池进行了模拟。结果表明:水解酸化池内流速分布很不均匀;池内存在大片回流区域以及流速几乎为零的区域,区域总体积占池容的50%以上;平均水力停留时间约为1 480 s,远达不到设计值。结合模拟结果,提出了改进方案。改进后的模拟结果表明:水解酸化池内水流流速分布均匀性大大提高;大片的回流区域消失,速度几乎为零的区域面积也大大减小;水解酸化池的空间得到充分利用,水下推进器的作用也更加明显;平均水力停留时间约为15 340 s,和设计值十分接近。但是仍存在一些不足:水流流速分布的均匀性仍存在一定缺陷;只考虑了单相流,没有考虑池中污泥的作用。  相似文献   

10.
The predictive potential of air quality models and thus their value in emergency management and public health support are critically dependent on the quality of their meteorological inputs. The atmospheric flow is the primary cause of the dispersion of airborne substances. The scavenging of pollutants by cloud particles and precipitation is an important sink of atmospheric pollution and subsequently determines the spatial distribution of the deposition of pollutants. The long-standing problem of the spin-up of clouds and precipitation in numerical weather prediction models limits the accuracy of the prediction of short-range dispersion and deposition from local sources. The resulting errors in the atmospheric concentration of pollutants also affect the initial conditions for the calculation of the long-range transport of these pollutants. Customary the spin-up problem is avoided by only using NWP (Numerical Weather Prediction) forecasts with a lead time greater than the spin-up time of the model. Due to the increase of uncertainty with forecast range this reduces the quality of the associated forecasts of the atmospheric flow.In this article recent improvements through diabatic initialization in the spin-up of large-scale precipitation in the Hirlam NWP model are discussed. In a synthetic example using a puff dispersion model the effect is demonstrated of these improvements on the deposition and dispersion of pollutants with a high scavenging coefficient, such as sulphur, and a low scavenging coefficient, such as cesium-137. The analysis presented in this article leads to the conclusion that, at least for situations where large-scale precipitation dominates, the improved model has a limited spin-up so that its full forecast range can be used. The implication for dispersion modeling is that the improved model is particularly useful for short-range forecasts and the calculation of local deposition. The sensitivity of the hydrological processes to proper initialization implies that the spin-up problem may reoccur with changes in the model and increased model resolution. Spin-up should be an ongoing concern for atmospheric modelers.  相似文献   

11.
The St. Lawrence River (SLR) is the second largest waterway in North America. The discharge of the City of Montreal wastewater treatment plant (WWTP) represents the largest volume of treated wastewaters being released into the river. It also ranks as the largest sewage treatment plant of its kind in North America. Over the last decade, intensive multidisciplinary research has focused on assessing the impacts of Montreal wastewater effluents on the SLR. We describe the major findings of these investigations, including the determination of the fate of contaminants, bioaccumulation in fish and invertebrates, ecotoxicological measurements of aquatic animal health, evaluation of endocrine disruption, parasitism in fish, and combined effects of multiple stressors on the SLR. Impacts of the effluents from the WWTP on aquatic organisms from the SLR are both toxicological and ecological, demonstrating the need for an integrated view of the impacts of municipal effluents on aquatic ecosystems.  相似文献   

12.
Background, aim, and scope  The first step in the restoration of a medieval stained glass window is the evaluation of its degree of degradation. This implies the study of the chemical composition of the stained glass as well as the new mineral phases developed on its surface (patinas). Patinas are clearly related to glass composition, time, environmental conditions, microenvironments developed in local zones, bioactivity, physical and chemical factors, etc. This study was carried out on patinas developed in selected Na-rich stained glass of the Santa Maria de Pedralbes Monastery (Barcelona, Spain). The location of this monument in the city (about 5 km from the shoreline and close to the Collserola hill flank) helped to determine the environmental conditions in which patinas developed. The aim of our study was to characterize the patinas formed on the surface of the selected glass of this monastery in order to understand the role of the chemical composition of the original glass (Na-rich) as well as the environmental conditions in which they developed. Materials and methods  Powdered samples of two different color-type patinas (ochre-orange and brownish) were collected in the external and internal parts of the stained glass windows of the Prebystery and Chapter House of the Pedralbes Monastery by using a precision (odontological) drill. These patinas were subsequently analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Results  XRD analyses evidenced the presence of sulfates (gypsum and thenardite), calcite, Ca-oxalates (whewellite and weddellite), and quartz forming part of the patinas. Although these mineral phases can be found in both color-type patinas, whewellite and thenardite are more common in the ochre-orange patinas. The results obtained were validated by the FTIR measurements. It has been observed, when thenardite is present, that gypsum occurs as traces. Thenardite is in most of the cases associated with whewellite and mainly occurs in the internal parts of the glass. In contrast, weddellite is limited to the absence of thenardite and whewellite and to the external parts of the stained glass. Quartz is present in all the patinas independent of their location and color. Calcite also occurs in many samples. It appears in both color-type patinas and, in some cases, is associated to the presence of weddellite but not to whewellite and/or thenardite. Discussion  Glass composition together with environmental conditions and location of the patinas (internal or external parts of the stained glass window), as well as the provenance of the glass within the monastery, are the main factors that define the development of the new mineral phases. Moreover, the action of microorganisms, when present, can also strongly influence the development of some mineral phases. For example, the formation of calcite in the external parts of the stained glass (associated with the presence of oxalates) is related to the action of microorganisms. When calcite is formed in the internal parts of the glass and it is not associated with the presence of Ca-oxalates, an inorganic origin can be invoked. The presence of weddellite requires a very humid microenvironment with very little exposure to sunlight. In fact, this mineral phase has only been observed in the external parts of some glass located in the humid and shady side of the monastery. Whewellite (which only appears in the internal parts) needs a low degree of relative humidity. It has been observed that sulfur precipitating in basically one mineral phase (thenardite or gypsum) depends on the microenvironmental conditions of the moment and the glass composition. When thenardite occurs, it can be maintained that the original glass is of Na composition. The occurrence of quartz in all samples is interpreted as being due to the deposition of atmospheric particulate matter. The color of the patinas can be originated by different processes (presence of carotenes, organic pigmentation, atmospheric contamination, etc.). Conclusions  In the case of moderately weathered stained glass windows, the combination of XRD and FTIR techniques is very useful to obtain a fast preliminary evaluation of the degree of weathering of a stained glass window. The presence of specific mineral phases in the patina (e.g., thenardite) confirms the Na composition of the original stained glass. This is important since Na-rich glass underwent a lesser degree of weathering than K- or K-Ca-rich glass. However, their absence cannot preclude other possibilities. It has been extensively evidenced through time that environmental conditions play an important role on the formation of the different mineral phases which form part of the patinas. Recommendations and perspectives  The first step in the restoration of a stained glass window is the evaluation of the degree of deterioration of the glass. This evaluation includes a chemical analysis of the glass as well as a characterization of the patinas developed on their surfaces. The obtained results will be essential in order to define the best restoration practices to be followed.  相似文献   

13.
Passive samplers are used in air quality monitoring for many years to compete in terms of being economical with continuous measurement systems. In this study, different amounts of single-wall carbon nanotubes (SWCNTs) were added in the impregnation solution of the filters of passive samplers and the effect on the absorption of ozone studied. The results of the measurement of ozone with varying amounts of SWCNTs added to the impregnation solution of the filters of the passive samplers were compared with the results of the continuous ozone measurement system (CS). Measurements were performed for 7 days and 14 days at two different exposure times. The increase of the amount of SWCNTs on the filters of the passive samplers, however, did not have an effect on the measurement of ozone. The measurement results of the passive samplers of the 14-day exposure periods, alternating with the 7-day exposure periods, were lower considerably than the results of the 7-day exposure.

Implications: The accuracy and the use of passive samplers in SWCNTs are expected to provide high measurement results. Observing the effect of the change in the amount of diffusion of pollutants held in the SWCNT is also one of the expected implications.  相似文献   


14.
Gawlik BM  Kettrup A  Muntau H 《Chemosphere》2000,41(9):1337-1347
The European reference soil set was introduced as common basis for a better comparability of soil sorption data measured within the framework of chemical testing of environmental chemicals. The success of the EUROSOILS, as the set is commonly called, convinced the European Commission's Joint Research Centre to evaluate the possibility of producing a remake of these unique and new type of reference materials maintaining the principal sorption-controlling properties of the soils. In this paper the recently proposed second generation of the EUROSOILS is used to evaluate a HPLC-screening technique for the estimation of soil adsorption coefficients of organic chemicals. It could be shown that the derived correlations between HPLC capacity factors of the test substances and the respective soil adsorption coefficients resulting from batch experiments with the second version of the EUROSOILS agreed with those derived for the first generation of reference soils at a different occasion.  相似文献   

15.
Sludge from mining exploitation can be a source of land and water contamination in the adjacent zone. Accidents such as the break of waste mining pools in the Aznalcollar Mine (Seville, Spain) in 1998 produce important ecological disasters. In this work is presented a study of the evolution of aqua regia leachable concentration and mobility of metals in sediment samples of Guadiamar River basin from the accident date up to 2001. The application of BCR standard extraction procedures provides valuable information about the mobility and toxicity of the spill and the metal mobility in Guadiamar River polluted sediments. As a rule, themobility of several metals in the initial sludge (sulphides) is low, except for copper. Otherwise, the results of aqua regia leachable concentration and mobility of metal obtained for sediments samples indicate that the cleaning and inertisation works carried out in the zone have been adequate but insufficient, being the metal levels observed in the zone are higher than natural levels. To establish the initial impact of the spill and the mobility changes with time, mineralogical composition of the pyritic sludge and its evolution after the natural weathering and after the induction, of accelerated ageing processes by light and temperature was studied in the laboratory. Oxidation of initial sulphides to sulphates was observed. Both environmental and laboratory oxidation of the metallic sulphides increase the mobility of all metals, especially of copper, zinc and lead. The proposed laboratory procedure allows to predict the changes in mobility and therefore in toxicity that can occur at short or long term after exposure of sludge at environ-mental conditions. The mobility results in sludge and sediment samples are interpreted in terms of the mineral composition of the samples.  相似文献   

16.
The impact of an industrial effluent containing high loads of calcium, cadmium, lead chloride and sulphate, on a river ecosystem was assessed using a combination of an effluent toxicity test, an ambient toxicity test and an ecological survey. Only this combination of techniques made it possible to discriminate between the effects of the discharge and those of the background pollution. Each of the individual techniques detected essential effects which the other failed to reveal. With the physical and chemical measurements, important increases of several components were measured at all sampling sites downstream of the discharge. With the ecological survey, however, no large changes in water quality could be determined at the sampling sites, due to the high degree of pollution present upstream of the discharge. Reproduction of Daphnia magna, exposed to sublethal effluent dilutions, was followed over two generations. The offspring of the first generation were shown to have an increased sensitivity to the effluent, compared to the first generation that was born from previously unexposed mothers. Besides the toxicity of the effluent, the acute and chronic toxicity of its main component, CaCl(2), was also determined. The results of the CaCl(2)-tests and toxicity data from literature for the suspected toxicants were transformed to Toxic Units (TU). Using the sum of the TUs we investigated the possibility of predicting effluent toxicity to Daphnia magna. Effluent toxicity was under-estimated by calculating the sum of the TUs of the individual components. Dilution of the effluent to a level at which the measured toxicant concentrations comply with European regulations still showed significant effects on Daphnia reproduction.  相似文献   

17.
本文研究了北京大气温度的变化与小儿呼吸道疾病的关系,结果表明北京大气温度升高与小儿呼吸道疾病的发生率呈负相关,rs=0.530,p<0.01,北京冬季小儿呼吸道疾病为小儿疾病发生率的首位,而且呈周期性变化,本文还讨论了小儿呼吸道疾病的病因及其防治。  相似文献   

18.
Räsänen T  Laakkonen S 《Ambio》2007,36(2-3):229-236
The Convention on the Protection of the Marine Environment of the Baltic Sea Area signed in 1974 in Helsinki is probably the most important environmental agreement consummated in the Baltic Sea region. This article is the first study that explores the history of this agreement, also known as the Helsinki Convention, by using primary archival sources. The principal sources are the archives of the Ministry for Foreign Affairs of Finland. We examine the role of Finland in the process that led to the signing of the Helsinki Convention from the perspective of international politics. The study focuses primarily on Finnish, Swedish, and Soviet state-level parties from the end of the 1960s to 1974. We show that Cold War politics affected in several ways negotiations and contents of the Helsinki Convention. We also argue that the Soviet Union used the emerging international environmental issues as a new tool of power politics.  相似文献   

19.
烧结法赤泥的强度演化规律   总被引:1,自引:0,他引:1  
筑坝堆存是现在处理赤泥的主要方式,为了堆场安全继续向上堆载,对烧结法赤泥强度的演变规律进行了研究。通过对比不同深度处赤泥的抗剪强度,表明赤泥强度的形成与堆载时间没有必然的联系;再通过对新进场的赤泥进行强度追踪,得到赤泥强度形成过程中抗剪强度与滤水固结时间的关系曲线,从时间因素上为赤泥的安全堆载提供一个理论依据。  相似文献   

20.
钢铁厂露天堆料场挡风抑尘墙效果的数值模拟   总被引:2,自引:0,他引:2  
对某钢铁厂露天堆料场设置挡风抑尘墙进行数值模拟研究,通过对动力阴影区覆盖面积的考察,分析了自然风速、墙高、墙开孔率及墙后建构筑物对挡风抑尘墙的挡风抑尘效果的影响.该钢铁厂露天堆料场设置防风抑尘墙的最佳几何尺寸是:墙长(L)为500 m,墙厚(d)为5 mm,墙高(H)为15~20 m,墙开孔率(k)为0.2~0.3,在主导风风速达到10 m/s以上的大风天气能够形成有效覆盖整个料场的动力阴影区,再配以合适的喷雾洒水或喷洒化学抑尘剂等其他抑尘手段就能够非常有效地抑制料场扬尘.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号