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11.
The acquisition of a comprehensive air quality dataset for a small city environment is described for use in statistical modelling of dispersion processes and micro-scale assessment of polluted zones. The dataset is based on a nitrogen dioxide diffusion tube survey for Cambridge where up to 80 roadside and background sites have been monitored continuously over two years, using a two week exposure period. Site categories are defined by their function within the urban landscape. Spatial and temporal features of the data set are explained in terms of urban location, street geometry, meteorology and traffic behaviour. The highest levels of NO2 are found in central canyon streets which are narrow with enclosing architecture and slow-moving traffic. In contrast lower levels are found for the wider, more open radial routes where traffic is free-flowing. The influence of street geometry on NO2 levels for central streets is demonstrated, where canyon sections adjacent to open sections having the same traffic flow record higher concentrations. Whilst all roadside sites are affected by a photochemical pollution 'episode', the greater potential for elevated NO2 concentrations within the canyon sections is significant. The close proximity of low background levels of NO2 to roadside 'hot-spots' is important for public exposure assessment. The variation in background levels across the urban landscape is very small and unrelated to location; whether central, suburban or outer city. Seasonal variation, not seen in roadside data, is clearly apparent in background data with a winter maximum and summer minimum. 相似文献
12.
Evaluation of heavy metal availability in polluted soils by two sequential extraction procedures using factor analysis 总被引:34,自引:0,他引:34
Maiz I Arambarri I Garcia R Millán E 《Environmental pollution (Barking, Essex : 1987)》2000,110(1):3-9
Superficial soil and grass samples from 13 locations affected by several anthropogenic sources (mining, metal factory, traffic emissions) were collected in Gipuzkoa, northern Spain. The more labile metal fractions, the mobile (extracted by 0.01 mol l(-1) CaCl(2)) and the mobilisable (extracted by 0.005 mol l(-1) DTPA), were evaluated using a short sequential procedure with two steps. From the results a short-medium term potential lability of Cd, Cu, Zn and Pb can be concluded. The labile levels were compared with the results obtained using the Tessier sequential procedure. Factor analysis was used to check the associations between the total metal contents in soil and grass, as well as between the levels of the different sequential fractions and the total content in grass. Cd, Cu and Zn labile levels were related to total metal grass contents indicating its suitability for the availability studies in polluted soil-plant system. 相似文献
13.
da Costa AO Silva PF Sabará MG da Costa EF 《Environmental monitoring and assessment》2009,155(1-4):527-538
This paper reports the using of neural networks for water quality analysis in a tropical urban stream before (2002) and after sewerage building and the completion of point-source control-based sanitation program (2003). Mathematical modeling divided water quality data in two categories: (a) input of some in situ water quality variables (temperature, pH, O2 concentration, O2 saturation and electrical conductivity) and (b) water chemical composition (N-NO2(-); N-NO3(-); N-NH4(+) Total-N; P-PO4(3-); K+; Ca2+; Mg+2; Cu2+; Zn2+ and Fe+3) as the output from tested models. Stream water data come from fortnightly sampling in five points along the Ipanema stream (Southeast Brazil, Minas Gerais state) plus two points downstream and upstream Ipanema discharge into Doce River. Once the best models are consistent with variables behavior we suggest that neural networking shows potential as a methodology to enhance guidelines for urban streams restoration, conservation and management. 相似文献
14.
The upper critical thermal limits were measured as heat-coma temperatures in Littorina species as a tool for examining physiological diversity. Thermal tolerance was found to be stable within a population, but
extensive variation occurred between populations and species. All species examined displayed heat-coma values of ∼30 °C and
did not show a positive correlation with shore height. Eulittoral-fringe species tended to have higher coma temperatures than
eulittoral species. Coma temperatures varied both seasonally and geographically. Lethal thermal limits were also investigated;
these were ∼10 C° higher than coma temperatures.
Received: 16 August 1999 / Accepted: 13 June 2000 相似文献
15.
Irati Legorburu José Germán Rodríguez Victoriano Valencia Oihana Solaun Ángel Borja Esmeralda Millán 《Chemistry and Ecology》2014,30(8):701-718
This contribution characterises the sources and distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments of the Basque coast (Bay of Biscay). Different source characterisation approaches (i.e. GIS assisted-chemometrics, PAH diagnostic ratios and analyses of composition profiles) were used in combination to successfully identify the factors determining the origin and distribution of PAHs. Urban/industrial combustion processes were identified as the main PAH source. However, the analysis of PAH composition patterns and diagnostic ratios identified secondary natural and petrogenic PAH sources on small spatial scales. The median ∑18PAH concentration ranged from 66 μg kg?1 (d.w.) to 7021 μg kg?1 (d.w.). The Ibaizabal estuary, which supports most of the anthropogenic pressure in the region (i.e. urban development, industrialisation, commercial and recreational harbours), also showed the highest PAH concentrations. On the shelf, human activities, hydrodynamic conditions and geomorphological features led to spatial differences in the PAH concentrations among sectors: the offshore and west sectors were characterised by higher concentrations, while the lowest values were found in the mid and east sectors. The results enhance the knowledge on PAH-related contamination processes and could be used to support the environmental assessment process required under current European marine legislation. 相似文献
16.
Moreno-Jiménez E Gamarra R Carpena-Ruiz RO Millán R Peñalosa JM Esteban E 《Chemosphere》2006,63(11):1969-1973
Mercury is a widely distributed environmental pollutant, able to induce toxicity in living organisms, including higher plants. Some plant species are able to grow in mine sites, like the Almadén zone in Spain. Our study focus on two of these plant species, Rumex induratus and Marrubium vulgare and their responses to natural Hg exposure. Total Hg concentration in the soil below the plants could be classified as toxic, although the available fraction was low. Hg availability was higher for the M. vulgare than for the R. induratus plot. Hg concentrations in field plants of R. induratus and M. vulgare grown on these soils can be considered as phytotoxic, although no symptoms of Hg toxicity were observed in any of them. According to the BAF ([Hg]tissue/[Hg]avail), R. induratus showed a higher ability in Hg uptake and translocation to shoots, as well as higher concentrations of MDA and –SH:Hg ratios, so that this plant is more sensitive to Hg than M. vulgare. The resistance to Hg and the capability to extract Hg from the soil make both M. vulgare and R. induratus good candidates for Hg phytoremediation of contaminated soils. 相似文献
17.
Climate warming is occurring in concert with other anthropogenic changes to ecosystems. However, it is unknown whether and how warming alters the importance of top-down vs. bottom-up control over community productivity and variability. We performed a 16-month factorial experimental manipulation of warming, nutrient enrichment, and predator presence in replicated freshwater pond mesocosms to test their independent and interactive impacts. Warming strengthened trophic cascades from fish to primary producers, and it decreased the impact of eutrophication on the mean and temporal variation of phytoplankton biomass. These impacts varied seasonally, with higher temperatures leading to stronger trophic cascades in winter and weaker algae blooms under eutrophication in summer. Our results suggest that higher temperatures may shift the control of primary production in freshwater ponds toward stronger top-down and weaker bottom-up effects. The dampened temporal variability of algal biomass under eutrophication at higher temperatures suggests that warming may stabilize some ecosystem processes. 相似文献
18.
This paper aims to consider the total cost, including polluting environmental emissions, of imports from China to Europe of five valve components in aluminium, steel and iron. These are compared with locally produced alternatives to investigate whether internalising such external costs affects their price competitiveness. Seaborne trade represents 90% of international trade and is growing faster than the world’s economy, but marine pollution emissions are not reflected in market prices. Chinese aluminium, iron and steel production are about 2.5 times more polluting than their European counterparts, but this is also not reflected in prices. In this paper both types of extra emissions are calculated, valued and added to the cost of the components analysed, for comparison with locally produced alternatives. The locally produced components generally remain uncompetitive with Chinese imports for all likely values of external cost, except for heavy aluminium components under high external cost assumptions. The Chinese iron components analysed are simply too low in cost for European (in this case Spanish) equivalents to be competitive even allowing for environmental costs; while the stainless steel ones are so small and light that transport cost, even including externalities, is not significant. While these specific results are of limited generalizability, they provide insight into an issue of considerable and growing importance. Some suggestions are offered for further research. 相似文献
19.
Cumulative effects assessment (CEA) in Canada is in dire straits. Despite a huge amount of talk and a flurry of developmental
activity associated with CEA concepts, it has not lived up to its glowing promise of helping to achieve sustainability of
diverse valued ecosystem components. This article aims to articulate that failure, to examine it in terms of six major problems
with CEA, and to propose solutions. The six problem areas include (1) application of CEA in project-level environmental impact
assessments (EIAs), (2) an EIA focus on project approval instead of environmental sustainability, (3) a general lack of understanding
of ecologic impact thresholds, (4) separation of cumulative effects from project-specific impacts, (5) weak interpretations
of cumulative effects by practitioners and analysts, and (6) inappropriate handling of potential future developments. We advocate
improvements not only within the purview of project-specific EIAs, but also mainly in the domain of region-scale CEAs and
regional environmental effects frameworks (or perhaps land use planning). Only then will the CEA begin to approach the promise
of securing sustainability of valued ecosystem components. 相似文献
20.
N. Castell E. Mantilla R. Salvador A.F. Stein M. Millán 《Journal of environmental management》2010,91(3):662-676
The characterization and evaluation of the impact that an industry is likely to have on the surrounding ozone levels is one of many problems confronting air quality managers and should be taken into consideration when authorizing its installation. The correct management of an environment, in terms of monitoring existing industries and planning new activities, requires adequate knowledge of the processes sustained by the industrial emissions therein.This paper explores the improvements in air quality management arising from taking into account the uncertainties involved in the photochemical modeling of the impact of an industry on surface ozone levels.For this, we evaluate the impact on ozone levels of a power plant located in an industrial area of southwestern Spain (Huelva). The evaluation takes into account the effects of both emissions' uncertainty and the non-linear chemistry between ozone and its precursors, thus providing a probable range of increase over the normative values (hourly and 8-hourly maximums) defined in the European Directive. The proposed methodology is easily applicable by air quality managers.Advanced modeling techniques were used for the power plant assessment, MM5 atmospheric modeling system, and air quality model CAMx. The results from meteorology and ozone forecasts have shown acceptable agreement with the observations.The spatial distribution of the impact is found to be strongly determined by mesoscale meteorological processes, which are reinforced by the local orography; there is also a marked temporal evolution. The industrial plume is observed to induce a decrease (or maintenance) of the ozone levels near the emission source (0–10 km), and an increase in the ozone concentrations farther away (with maximums between 10 and 50 km). In fact, in the meteorological episodes with a predominance of local breeze circulations, impacts have been detected at distances of more than 100 km from the emission source.Sensitivity of the power plant impact to variations in ozone precursor emissions is described, and the scenarios and the points in the domain presenting higher sensitivity and registering larger impacts are also identified. The results show that the largest impacts take place in emission scenarios where the NOx has been reduced with respect to the base case scenario. In contrast, in scenarios where the VOC emissions are reduced with respect to the base case scenario, the impact is smaller or remains unchanged. This is important in areas like the study case, where there is a high percentage of biogenic VOC emissions and the industrial areas are close to natural protected areas and agricultural fields. 相似文献