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排序方式: 共有54条查询结果,搜索用时 187 毫秒
1.
Jean-Franois Viel Elisabeth Cardis Monika Moissonnier Ren de Seze Martine Hours 《Environment international》2009,35(8):1150-1154
Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. The main goal of this survey is to assess individual RF exposure on a population basis, while clarifying the relative contribution of different sources to the total exposure. A total of 377 randomly selected people were analyzed. Each participant was supplied with a personal exposure meter for 24-hour measurements (weekday), and kept a time–location–activity diary. Electric field strengths were recorded in 12 different RF bands every 13 s. Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201 V/m, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044 V/m), followed by WiFi-microwaves (0.038 V/m), cordless phones (0.037 V/m), and mobile phones (UMTS: 0.036 V/m, UMTS: 0.037 V/m). Various factors, however, contributed to a high variability in RF exposure assessment. These population-based estimates should therefore be confirmed by further surveys to better characterize the exposure situation in different microenvironments. 相似文献
2.
Lack of sufficiently detailed data often limits the applicability of complex transport-reaction models for estimating potential herbicide loss to surface waters. Therefore, there is also a need for simple models that are easy to apply but still capture the main features of the underlying processes.In this study, a simple regression model was developed to assess the vulnerability of catchments in the Swiss Plateau to diffuse herbicide loss to surface waters. The model is designed as a screening tool to rank the catchments in a relative sense and not to calculate Predicted Environmental Concentrations (PEC) of pesticides. The main goal is to capture two dominating factors controlling diffuse herbicide transport into streams and rivers. These factors are herbicide application and fast flow processes that are mainly responsible for herbicide transport. In a first step vulnerability of sites to herbicide loss is estimated based on site-specific conditions irrespective of actual herbicide application. In the second step, this vulnerability assessment is combined with actual herbicide application data to estimate the potential herbicide loss.The fast flow index (FFI), derived from discharge data using a base flow separation method, was applied as a proxy for the amount of fast flow occurring. The influence of catchment attributes (including topographic, climatic and soil data) on the FFI was analyzed using a multiple regression approach based on data from 57 catchments of the Swiss Plateau. By combining regression analysis with mechanistic knowledge, a two factor non-linear model based on river density and soil permeability as dominant input factors was selected as the best model for FFI prediction given the available data. Higher dimensional models had to be excluded because the strong correlation between the potential input factors led to unrealistic dependences while only minimally improving the quality of the fit.The spatial pattern of the predicted FFI as a measure for the vulnerability to diffuse herbicide losses shows a clearly increasing trend from the western to the eastern part of the Swiss Plateau and towards the pre-alpine/alpine regions in the south.In general the pattern of herbicide use corresponds to site conditions typical of a low FFI. However, the spatial analysis revealed exceptions, namely areas in which high actual herbicide use coincides with a high FFI.Despite the uncertainties in the model, this simple approach seems to be useful for supporting site-adapted agricultural practice whenever the higher accuracy of more detailed models is not required or too expensive to achieve. In addition, in combination with data on actual herbicide application, it can support the design of monitoring strategies by identifying critical areas of actual herbicide loss. 相似文献
3.
4.
We report observations of disappearance of Erica tetralix in wet heathland, which is unlikely to be caused by competition, as E. tetralix is dying before its place is taken up by other species. To investigate the causes, we used both old and new data. Results showed that presence of Molinia caerulea and Calluna vulgaris were substantial in the former E. tetralix dominated areas. Measurements of the C/N ratio in the morlayer were between 21 and 26 under the E. tetralix stands. As the expected C/N ratio in a healthy nutrient poor ecosystem like the E. tetralix wet heathland is around 30, this indicates that the ratio is probably decreasing and, correspondingly, the probability of nitrogen leaching from the ecosystem is increasing. The morlayer pH was extremely low—between 3.03 and 3.78. This represents a pH decline since the 1960s, where pH values generally were above 4. This supports the hypothesis that the decrease in morlayer pH is the major factor explaining the disappearance of E. tetralix and that measures to increase pH should be considered as part of the recommendations for relevant future management.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-012-0251-z) contains supplementary material, which is available to authorized users. 相似文献5.
Long-term (1860–2010) catchment mass balance calculations rely on models and assumptions which are sources of uncertainty
in acidification assessments. In this article, we report on an application of MAGIC to model acidification at the four Swedish
IM forested catchments that have been subject to differing degrees of acidification stress. Uncertainties in the modeled mass
balances were mainly associated with the deposition scenario and assumptions about sulfate adsorption and soil mass. Estimated
base cation (BC) release rates (weathering) varied in a relatively narrow range of 47–62 or 42–47 meq m−2 year−1, depending on assumptions made about soil cation exchange capacity and base saturation. By varying aluminum solubility or
introducing a dynamic weathering feedback that allowed BC release to increase at more acidic pHs, a systematic effect on predicted
changes in acid neutralizing capacity (ΔANC ca. 10–41 μeq l−1) and pH (ca. ΔpH = 0.1–0.6) at all sites was observed. More robust projections of future changes in pH and ANC are dependent
on reducing uncertainties in BC release rates, the timing, and extent of natural acidification through BC uptake by plants,
temporal changes in soil element pools, and fluxes of Al between compartments. 相似文献
6.
M. S. Cresser Z. Parveen R. Smart C. Deacon S. M. Gammack C. White 《Chemistry and Ecology》2013,29(3-4):195-212
Ammonium sulphate at six concentrations in simulated precipitation has been applied weekly over two years to Calluna vulgaris growing in peat soil. The nitrogen deposition treatments were chosen to embrace and exceed critical load. The growth and composition of the Calluna and the changes over time in the chemistry of the peat soil and its soil solution were monitored. In spite of significant increases in foliar nitrogen concentration in new shoots, especially in the first year, growth did not increase significantly in response to nitrogen treatment. Several factors could be contributing to the lack of significant growth response. (1) Increasing ammonium input significantly acidified the soil solution, which could adversely effect growth directly. (2) Foliar calcium concentration was reduced significantly in both years by the ammonium sulphate treatments, and more calcium was undoubtedly lost from the rooting zone at higher nitrogen inputs. (3) Foliar phosphate declined significantly between the first and second year, so lack of growth response might also reflect a phosphorus limitation. There was a distinctly visible darkening of the leaves in response to increasing ammonium applications, especially for the first year's growth, and the chlorophyll a and b concentrations in leaves from new growth at the three highest nitrogen treatments were significantly (at P <0.05) higher than those for the control. The pigment concentrations fell markedly by the end of the second season, and treatment effects were much less consistent. It is suggested that pigment analysis therefore probably has little diagnostic value for assessing damage from pollutant nitrogen effects. 相似文献
7.
In areas of varying geology, it is difficult to infer water quality from specific conductance or electrical conductivity (EC) data without an understanding of the expected range of EC values based on local bedrock composition. This paper describes a user-friendly graphical screening method that addresses this issue by plotting the EC against concurrent alkalinity data, which correlates well with the presence of carbonate bedrock under natural conditions, and thus serves as an index of bedrock type. The upper limit of EC vs. alkalinity expected in a stream is determined using regional groundwater quality data, based on the assumption that stream chemistry reflects groundwater under baseflow conditions. Stream samples with EC/alkalinity values that consistently plot above this limit are considered impacted by anthropogenic sources. The effect of dilution and runoff on the EC vs. alkalinity plot of stream samples is considered using a simple baseflow/storm runoff-mixing model. The graphical method's utility as a screening tool is demonstrated by application to stream chemistry data from watersheds of southeastern Pennsylvania and northwestern New Jersey in several distinct geologic settings; however the method is general and widely applicable to watersheds in humid temperate regions. Its use is intended for watershed stewards of both professional and nonprofessional qualification. 相似文献
8.
利用主动观测技术对宁东能源化工基地大气PM2.5、PM1.0和气相中的PAHs浓度水平、族谱特征、时空分布及来源进行研究,并基于该观测数据对居民呼吸暴露健康风险进行评估.结果表明,宁东基地大气PM2.5、PM1.0及气相中∑16PAHs浓度范围分别为:17.95~325.12ng/m3、12.66~311.96ng/m3和26.33~97.88ng/m3,年均浓度分别为(99.42±117.48)ng/m3、(78.88±100.58)ng/m3和(57.89±47.39)ng/m3.宝丰基地冬夏季大气PM2.5、PM1.0和气相中∑16PAHs浓度水平均明显高于英力特;宝丰和英力特基地冬季大气PM2.5、PM1.0中∑16PAHs浓度水平均明显高于夏季浓度.宁东基地大气中∑16PAHs的浓度水平要高于国内外其他城市,大气PAHs污染较为严重.源解析表明夏季宁东基地PAHs的主要排放源是工业煤燃烧和机动车尾气,冬季则主要来自工业煤燃烧和木材、薪柴等生物质燃烧排放.宁东基地人群暴露于大气PAHs可能会造成平均冬季每百万人中约有33~2628人罹患癌症,夏季每百万人中约有11~834人罹患癌症的风险. 相似文献
9.
S. Ghosh 《国际发展与全球生态学杂志》2019,26(4):344-353
In September 2015, the Sustainable Development Goals (SDGs) were endorsed by the United Nations and adopted by all 193 Member States. The SDGs integrate the 5P’s: People, Planet, Prosperity, Peace, and Partnership and clearly stress the need for all stakeholders to collaborate to create a sustainable world. Most importantly, the SDGs appeal to the central and diverse role that the business sector can play to deliver on the SDGs. This paper provides an analysis of inclusive business (IB) models as market-based solutions to contribute to the achievement of the SDGs and benefit those at the Base of the Pyramid (BoP). We investigate the IB models and their social impact in 20 organizations from emerging economies across five different sectors. The findings should help increase the uptake and scale of quality IB models and practices among the private sector, development communities, and governments to promote inclusive economic growth and social impact. 相似文献
10.
Dynamics in the global protected-area estate since 2004 总被引:1,自引:0,他引:1
Edward Lewis Brian MacSharry Diego Juffe-Bignoli Nyeema Harris Georgina Burrows Naomi Kingston Neil D. Burgess 《Conservation biology》2019,33(3):570-579
Nations of the world have committed to a number of goals and targets to address global environmental challenges. Protected areas have for centuries been a key strategy in conservation and play a major role in addressing current challenges. The most important tool used to track progress on protected-area commitments is the World Database on Protected Areas (WDPA). Periodic assessments of the world's protected-area estate show steady growth over the last 2 decades. However, the current method, which uses the latest version of the WDPA, does not show the true dynamic nature of protected areas over time and does not provide information on sites removed from the WDPA. In reality, this method can only show growth or remain stable. We used GIS tools in an approach to assess protected-area change over time based on 12 temporally distinct versions of the WDPA that quantify area added and removed from the WDPA annually from 2004 to 2016. Both the narrative of continual growth of protected area and the counter-narrative of protected area removal were overly simplistic. The former because growth was almost entirely in the marine realm and the latter because some areas removed were reprotected in later years. On average 2.5 million km2 was added to the WDPA annually and 1.1 million km2 was removed. Reasons for the inclusion and removal of protected areas in the WDPA database were in part due to data-quality issues but also to on-the-ground changes. To meet the 17% protected-area component of Aichi Biodiversity Target 11 by 2020, which stood at 14.7% in 2016, either the rate of protected-area removal must decrease or the rate of protected-area designation and addition to the WDPA must increase. 相似文献