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 42 毫秒
1.
Environmental Science and Pollution Research - Moroccan employers have a strong responsibility for the safety and health of their employees in the workplace and for protecting them from the risk of...  相似文献   

2.
The Bulgarian dispersion model 'Eulerian Model for Air Pollution' (EMAP) is used to estimate the sulphur pollution over the Balkan region for the period 1995–2000. A subdomain of the European Monitoring and Evaluation Programme (EMEP) grid is chosen containing 12 countries. The computational grid in this domain has a space step of 25 km, twice as fine as the EMEP grid. The former operational DWD 'Europa-Model' is used as meteorological driver. The source input is the official EMEP emission data. Monthly calculations are made having the last moment fields from the previous month as initial conditions for the next one. The boundary conditions are set to zero, so the influence of other European sources is not accounted for in this study. According to the EMEP methodology, multiple runs are made setting every time the sources of various countries to zero. The impact of every country in the pollution of all others is estimated.  相似文献   

3.
The products of the OH radical-initiated oxidation of dimethyl sulphide (DMS) have been investigated as a function of temperature (284, 295, and 306 K) and different initial NOx (NO+NO2) concentrations: initial NO was varied between 434 and 2821 ppb and NO2 between 135 and 739 ppb. The experiments were performed at 1000 mbar total pressure in synthetic air using the photolysis of H2O2 as the OH-radical source and FT-IR spectroscopy to monitor reactants and products. The major sulphur-containing products identified were SO2, dimethyl sulphoxide (DMSO), dimethyl sulphone (DMSO2), methane sulphonic acid (MSA), methane sulphonyl peroxynitrate (MSPN) and OCS. The variation of the product yields with temperature and NOx concentration are consistent with the occurrence of both addition and abstraction channels in OH radical-initiated oxidation of DMS. Distinct trends in the yields of the various products have been observed as a function of temperature, initial NOx conditions and also reaction time as NO is consumed in the system. Increasing the initial NO concentration was found to depress the DMSO, SO2 and OCS formation yields and enhance those of DMSO2, MSA and MSPN. The yield–time behaviour of DMSO2 is supportive of a formation mechanism involving addition of O2 to a (CH3)2SOH adduct, formed via the addition channel, followed by sequential reactions with NO and O2. The mechanisms controlling the concentration–time profiles of the individual products under the present experimental conditions are discussed in detail and consideration is given to possible implications for the photo-oxidation of DMS under ambient conditions.  相似文献   

4.
The effect of buildings on the dry deposition of dust particles was investigated in Be'er-Sheva, a desert city with about 140,000 inhabitants in southern Israel, and at two reference points in the surrounding rural area. The mineral and chemical composition of dust sampled at all sites was similar, reflecting the composition of the local loess soil, its likely origin. However, dust deposited in the traps set up in the vicinity of buildings in the city was significantly coarser than the dust which accumulated in similar traps at exposed sites in the countryside. The amount of dust (by weight) in the urban dust traps was on an average more than twice the amount deposited in the rural area. The differences in grain-size distribution and quantity of dust are attributed to the properties of the urban wind field and to various effects of human activity in the city.  相似文献   

5.
In 1997, the United States National Ambient Air Quality Standard (NAAQS) for ozone was revised from a 1-h average of 0.12 parts per million (ppm) to an 8-h average of 0.08 ppm. Analysis of ozone data for the ensemble of the contiguous United States and for the period 1980–1998 shows that the average number of summer days per year in exceedance of the new standard is in the range 8–24 in the Northeast and in Texas, and 12–73 in southern California. The probability of exceedance increases with temperature and exceeds 20% in the Northeast for daily maximum temperatures above 305 K. We present the results of several different approaches to analyzing the long-term trends in the old and new standards over the continental United States from 1980 to 1998. Daily temperature data are used to resolve meteorological variability and isolate the effects of changes in anthropogenic emissions. Significant negative trends are found in the Northeast urban corridor, in the Los Angeles Basin and on the western bank of Lake Michigan. Temperature segregation enhances the detection of negative trends. Positive trends occur at isolated sites, mostly in the Southeast; a strong positive trend is found in Nashville (Tennessee). There is some evidence that, except in the Southwest, air quality improvements from the 1980s to the 1990s have leveled off in the past decade.  相似文献   

6.
Inhalable particulate matter (PM10) concentrations were measured over 24-h intervals at six different urban sites in the city of Chillán from September 2001 to April 2003. Sampling locations were selected to represent central city, commercial, residential, and industrial portions of the city. Chemical composition of PM10 was performed to samples of 47 mm diameter Teflon membranes within the city of Chillán. The spatial and temporal variability of the chemical composition of PM10 was evaluated taking into account additional data from meteorology and further air pollutants. The majority of PM mass was comprised of carbon, nitrate, sulfate, ammonium, and crustal components but in different proportion on different days and at different sites. The chemical analyses showed that carbonaceous substances and crustal material were the most abundant component of PM10 during the winter and summer, respectively. The concentrations of PM10 were higher during the cold season than during the warm season. The PM10 concentrations were higher in the downtown area of the city of Chillán, where also the chemical composition was more variable due to urban traffic and other anthropogenic sources.  相似文献   

7.
In-situ bio-remediation is a viable cleanup alternative for aquifers contaminated by hydrocarbons such as BTEX. Transport models of varying complexity and capabilities are used to quantify their degradation. A model that has gained wide acceptance in applications is BIOPLUME II, which assumes that oxygen-limited biodegradation takes place as an instantaneous reaction. In this work we have employed theoretical analysis, using non-dimensional variables, and numerical modelling to establish a quantitative criterion demarcating the range of validity of the instantaneous reaction approximation against biodegradation kinetics. Oxygen was the limiting species and sorption was ignored. This criterion relates (o), the Dahmk?hler number at oxygen depletion, to O(o)*, the ratio of initial to input oxygen concentration, (o) > or = 0.7(O(o)*)(2) + 0.1O(o)* + 1.8. The derived (o) reflects the intrinsic characteristics of the physical transport and of the biochemical reaction, including the effect of biomass density. Relative availability of oxygen and hydrocarbons exerts a small influence on results. Theory, verified and refined via numerical simulations, showed that significant deviations of instantaneous reactions from kinetics are to be expected in the space-time region s相似文献   

8.
In April 1998, a holding lagoon containing pyrite ore processing waste rich in arsenic, failed and released 5-6 million m(3) of highly polluting sludge and acidic water. Over 2700 ha of the internationally important Do?ana National and Natural Parks were contaminated. The area of Natural Park to sustain the greatest impact was known as the Entremuros. This paper presents 0-5 cm soil monitoring data from the Entremuros, from sampling campaigns 6 and 18 months after the disaster; as well as macrophyte root, rhizome and stem data from samples taken 18 months after the spill. Results show a clear, decreasing, north-south arsenic soil pollution trend, both 6 and 18 months after the spill, and suggest a small reduction in total soil arsenic levels occurred over time; although a significant increase in extractable arsenic is also noted. The two macrophytes (Typha dominguensis and Scirpus maritimus) studied herein are not accumulating arsenic in stem parts, however, accumulation of arsenic on iron plaque on the roots of these plants may be occurring. Further work is recommended in order to determine the ecotoxicological significance of this process in relation to the avian food-chains of Do?ana, and elsewhere.  相似文献   

9.
The general objective of this work was to develop a monitoring and management model for aquatic plants that could be used in reservoir cascades in Brazil, using the reservoirs of AES-Tietê as a study case. The investigations were carried out at the reservoirs of Barra-Bonita, Bariri, Ibitinga, Promiss?o, and Nova-Avanhandava, located in the Tietê River Basin; Agua Vermelha, located in the Grande River Basin; Caconde, Limoeiro, and Euclides da Cunha, which are part of the Pardo River Basin; and the Mogi-Gua?u reservoir, which belongs to the Mogi-Gua?u River basin. The main products of this work were: development of techniques using satellite-generated images for monitoring and planning aquatic plant control; planning and construction of a boat to move coating plant masses and an airboat equipped with a DGPS navigation and application flow control system. Results allowed to conclude that the occurrence of all types of aquatic plants is directly associated with sedimentation process and, consequently, with nutrient and light availability. Reservoirs placed at the beginning of cascades are more subject to sedimentation and occurrence of marginal, floating and emerged plants, and are the priority when it comes to controlling these plants, since they provide a supply of weeds for the other reservoirs. Reservoirs placed downstream show smaller amounts of water-suspended solids, with greater transmission of light and occurrence of submerged plants.  相似文献   

10.
Quantitative assessments have long been used to evaluate the condition of the natural environment, providing information for standard setting, adaptive management, and monitoring. Similar approaches have been developed to measure environmental governance, however, the end result (e.g., numeric indicators) belies the subjective and normative judgments that are involved in evaluating governance. We demonstrate a framework that makes this information transparent, through an application of the Freshwater Health Index in three different river basins in Latin America. Water Governance is measured on a 0–100 scale, using data derived from perception-based surveys administered to stakeholders. Results suggest that water governance is a primary area of concern in all three places, with low overall scores (Guandu-26, Alto Mayo-38, Bogotá-43). We conclude that this approach to measuring governance at the river basin scale provides valuable information to support monitoring and decision making, and we offer suggestions on how it can be improved.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01407-8) contains supplementary material, which is available to authorized users.  相似文献   

11.
Environmental Science and Pollution Research - This study aimed to examine the role of effective employee training in the sustainable growth and corporate social responsibility of hotels during the...  相似文献   

12.
Environmental Science and Pollution Research - Diabetes is one of the most comprehensive metabolic disorders and is spread across the globe. The data from IDF Diabetes Atlas and National Diabetes...  相似文献   

13.
To evaluate sediment quality in different areas in the Gulf of Cádiz affected by mining activities, an integrative approach to assessment was used: the Sediment Quality Triad (SQT). Sediment samples were collected at six stations and subjected to replicated sediment acute and chronic toxicity tests, and comprehensive sediment chemistry analyses. Organisms collected synoptically at the same stations were analyzed for histopathological lesions and chemical concentrations in their tissues to determine 'in situ' alteration and bioavailability, in place of benthic community structure. The results obtained for each component were linked to the SQT using different methodologies of interpretation and expression of the integrated approach: (a) multivariate analysis, (b) significant statistical differences compared to the reference stations, (c) ANOVA-based pie charts, and (d) classical methods using triangles and the SQT index of pollution. SQT results indicated that the highest pollution was mainly associated with metals from mining activities and polyaromatic hydrocarbons in the Ría of Huelva. The use of histopathological measures and bioaccumulation of metals, improved the characterization of 'gray areas' of pollution and in the determination of the bioavailability of metals.  相似文献   

14.
Environmental Science and Pollution Research - Microplastics (MPs) pervade the environment and increasingly threaten both natural ecosystems and human health. In this study, we investigated MP...  相似文献   

15.
Brown JC  Koeppe M  Coles B  Price KP 《Ambio》2005,34(6):462-469
The recent rise in Brazilian soybean production has generated concern among the environmental community and some authors that natural tropical environments of the Amazon Basin are being converted to soybean fields. Proponents of soybean production counter that soybeans represent a viable agricultural commodity for the region; environmental concern is unwarranted, because new soybean fields are replacing already deforested or otherwise transformed lands. Both arguments have been made without comprehensive study and measure of land-use/land-cover (LULC) in areas undergoing expansion of soybean production. This case study, conducted in the municipality of Vilhena, Rond?nia, Brazil, in the southwestern Amazon Basin, uses remote sensing to evaluate the LULC accompanying this municipality's large growth in soybean production from 1996 to 2001. Forests are being converted for soybean production, but most of the production increase appears attributable to slight expansion of already existing fields, conversion of already deforested land, and higher yields.  相似文献   

16.
17.
Environmental Science and Pollution Research - The determination of trace-level pharmaceuticals in water is generally performed using liquid chromatography combined with mass spectrometry, which is...  相似文献   

18.
From 1990 to 1994 at Alert, Nunavut, Canada, weekly snow samples were collected under low wind conditions to avoid contamination by blowing snow. They were analysed for major ions, Br, and the organic ions methylsulphonate, formate, acetate and propionate. In the Arctic, where annual precipitation is low and blowing snow is common, these observations are unique. On an equivalent weight basis, acids and sea salt in snowfall are mixed approximately equally from December to January but from March to May acids dominate. The acidity of snowfall increases progressively throughout the winter to a May peak of ∼16 μeq l−1. SO42−, Br, and the organic acids acetate, and propionate peak in snowfall after polar sunrise indicate the influence of enhanced photochemical reactions. The greater enrichment of halides relative to sea salt Na+ in snow compared to aerosols indicates that gaseous uptake by snowflakes is important in the removal of these substances from the atmosphere and their deposition on to the Earth's surface. There is a marked difference between the seasonal variation of enrichment of Cl and Br in snow. The latter show a marked increase after polar sunrise while the former does not. These results provide valuable baseline information on the ionic content of fresh snowfall to be used in understanding the results of snowpack chemistry and post-depositional process studies conducted in the high Arctic.  相似文献   

19.
Environmental Science and Pollution Research - Water stored in open-pit lakes can be a water resource when the mine is closed. This study aimed to develop a reliable model to evaluate the water...  相似文献   

20.
A four and a half year study of ozone concentrations in the Central Mediterranean was carried out between January 1997 and August 2001 on a background monitoring station located on the island of Gozo midway between Southern Europe and North Africa.Seasonal and diurnal variations of background ozone are documented. They show the existence of seasonal cycles with a primary maximum in spring followed by a secondary, more variable maximum in summer which indicates that photochemically produced ozone is being transported over the Mediterranean to the rural island of Gozo. Although peak ozone concentrations seldom exceeded 100 ppbv during summer, the background ozone-mixing ratios (as monthly averages) are some of the highest values which can be found at low latitude sites throughout the world. An increasing trend in the annual background ozone concentration from 48.2 ppbv in 1997 to 52.2 ppbv in 2000 is observed. During wintertime the average ozone mixing-ratio (as monthly averages) of 44 ppbv in December is approximately twice as high as on the European continent. This may imply that on Malta, due to higher average ozone concentrations between autumn and spring (the main growing season), crop damage of high economic value may occur.  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