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391.
The Landscape Development Intensity index (LDI), which is based on non-renewable energy use and integrates diverse land use
activities, was compared to other measures of LU (e.g., %agriculture, %urban) to determine its ability for predicting benthic
diatom composition in freshwater marshes of peninsular Florida. In this study, 70 small, isolated herbaceous marshes located
along a human disturbance gradient (generally agricultural) throughout peninsular Florida were sampled for benthic diatoms
and soil and water physical/chemical parameters (i.e., TP, TKN, pH, specific conductance, etc.). Landscape measures of percent
agriculture, percent urban, percent natural, and LDI index values were calculated for a 100 m buffer around each site. The
strongest relationships using Mantel's r statistic, which ranges from −1 to 1, were found between benthic diatom composition, the combined soil and water variables,
and LDI scores (r=0.51, P<0.0001). Although similar, soil and water variables alone (r=0.45, P<0.0001) or with percent agriculture or percent natural were not as strongly correlated (both Mantel's r=0.46, P<0.0001). Little urban land use was found in the areas surrounding the study wetlands. Diatom data were clustered using flexible
beta into 2 groups, and stepwise discriminant analysis identified specific conductance, followed by LDI score, soil pH, water
total phosphorus, and ammonia, as cluster-separating variables. The LDI explained slightly more of the variation in species
composition than either percent agriculture or percent natural, perhaps because the LDI can combine disparate land uses into
a single quantitative value. However, the ecological significance of the difference between land use metrics and diatom composition
is controvertible, and additional tests including more varied land uses appear warranted. 相似文献
392.
David Fowler Rognvald Smith Jennifer Muller John Neil Cape Mark Sutton Jan Willem Erisman Hilde Fagerli 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):41-47
Emissions of sulphur and oxidized nitrogen compounds in Europe have been reduced following a series of control measures during
the last two decades. These changes have taken place during a period in which the primary gases and the wet deposition throughout
Europe were extensively monitored. Since the end of the 1970s, for example land based sulphur emissions declined by between
90 and 70% depending on the region. Over the same period the total deposition of sulphur and its partitioning into wet and
dry deposition have declined, but the spatial pattern in the reduction in deposition differs from that of emission and has
changed with time. Such non-linearities in the emission-deposition relationship are important to understand as they complicate
the process of assessing the effects of emission reduction strategies. Observed non-linearities in terrestrial sulphur emission-deposition
patterns have been identified in north west Europe due to increases in marine emissions, and are currently slowing the recovery
of freshwater ecosystems. Changes in the relative amounts of SO2 and NH3 in air over the last two decades have also changed the affinity of terrestrial surfaces for SO2 and have therefore changed the deposition velocity of SO2 over substantial areas. The consequence of this effect has been the very rapid reduction in ambient SO2 concentration in some of the major source areas of Europe, where NH3 did not change much. Interactions between the different pollutants, generating non-linearities are now being incorporated
in long-range transport models to simulate the effects of historical emission trends and to provide projections into the future.
This paper identifies non-linearities in emission deposition relationships for sulphur and nitrogen compounds in Europe using
data from the EMEP long-rang transport model and measured concentration fields of the major ions in precipitation and of SO2 and NO2 in surface air. 相似文献
393.
Spatio‐Temporal Patterns of Open Surface Water in the Central Valley of California 2000‐2011: Drought,Land Cover,and Waterbirds
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394.
Indicators of ecosystem recovery 总被引:6,自引:0,他引:6
395.
Robert J. Pheasant Mark N. Fisher Greg R. Watts David J. Whitaker Kirill V. Horoshenkov 《Journal of environmental psychology》2010,30(4):501-509
In a world of sensory overload, it is becoming increasingly important to provide environments that enable us to recover our sense of well being. Such restorative (‘tranquil’) environments need to comprise sufficient sensory stimulation to keep us engaged, whilst at the same time providing opportunity for reflection and relaxation. One essential aspect in safeguarding existing, or developing new ‘tranquil space’, is understanding the optimum relationship between the soundscape and the visual composition of a location. This research represents a first step in understanding the effects of audio-visual interaction on the perception of tranquillity and identifies how the interpretation of acoustic information is an integral part of this process. By using uni and bi-modal auditory-visual stimuli in a two stage experimental strategy, it has been possible to measure the key components of the tranquillity construct. The findings of this work should be of particular interest to those charged with landscape management, such as National Park Authorities, Regional Councils, and other agencies concerned with providing and maintaining public amenity. 相似文献
396.
使用超高效液相色谱ACQUITY UPLC快速分析醛酮类化合物 总被引:2,自引:0,他引:2
Mark E Benvenuti 《环境化学》2008,27(4):549-550
醛酮类化合物是焚烧过程扩散到环境中的产物,这些化合物大部分都是已知的致癌物.因此,美国EPA和一些州开发了分析这些化合物的方法,包括US EPA TO5 (空气),方法554 (饮用水),方法8315 A选项1和2 (废水、土壤和空气),以及加利福尼亚州方法1004 (羰基化合物,机动车排放尾气中的醇类氧化物).这些方法使用二硝基苯肼(DNPH)衍生化这些化合物,然后用HPLC分离并紫外检测(吸收波长360nm),目标分析物因方法的不同而略有不同.当前使用的方法运行时间超过40min以上,需要设置多种色谱柱方可达到可接受的化合物分离度. 相似文献
397.
This paper tests an equilibrium condition from a model that incorporates: (1) altruism of parents toward their young children, and (2) household production of latent health risks. The model demonstrates that an altruistic parent's marginal rate of substitution between an environmental health risk to herself and to her child is equal to the ratio of marginal risk reduction costs. Econometric estimates support this prediction based on data from a stated preference survey involving 488 parents of children aged 3–12 years. This outcome implies that parents reallocate family resources to at least partly offset the effectiveness of public programs that aim to reduce their children's environmental risks. 相似文献
398.
The Humic Lake Acidification Experiment (HUMEX) was launched in 1988 to study the role of humic substances in the acidification of surface waters and the impacts of acidic deposition on the chemical and biological properties of humic substances. This subproject was designed to determine the contribution of organic acids to the acidity of Lake Skjervatjern (the HUMEX Lake) and the impacts of the acidification on the characteristics of organic carbon. In order to get an empirical measure for organic acidity, dissolved organic carbon (DOC) was fractionated, isolated, and base-titrated from each half of Lake Skjervatjern. Hydrophobic acids were the dominant organic carbon fraction; the total organic acid content was generally greater than 80% of the DOC. The reliability of the fractionation procedure was tested with synthetic acids and the Nordic Fulvic acid. The DOC fractions did not show high variation over the 1.5-y acidification period. Hydrophilic acids had consistently greater exchange acidities compared to hydrophobic acids, averaging 12.9 μeq/mg DOC vs. 10.9 μeq/mg DOC, respectively. The dissociation of organic acids during acid-base titrations clearly increased with increasing pH. The high organic anion contribution to the ion balances indicates that humic matter is an important acidity source in Lake Skjervatjern. There are slight signs that the contribution of organic acids to overall lake acidity has decreased since acidification was initiated. 相似文献
399.
We develop a general model for pricing a depletable, replaceable asset, and discuss its application in determining optimal tipping fees for a sanitary landfill. We show that the optimal fee includes a component that grows at the real interest rate as space in the landfill is depleted, and then drops when a new landfill is built. Because the scarcity cost of landfill space increases as the landfill is filled, it may be optimal to delay a waste reduction program (such as recycling, composting, or incineration) until the landfill is partially full. 相似文献
400.