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1.
对永瓣藤总糖、粗脂肪、灰分、维生素C、磷、钾和各类氨基酸的含量进行了测量和分析,并对这些化学成分在不同部位的含量进行了比较。不同部位化学成分的含量存在一定的差异,除灰分外,其它化学成分含量均是叶高于茎、嫩茎高于老茎。  相似文献   

2.
Boosted regression tree (BRT) models were developed to quantify the nonlinear relationships between landscape variables and nutrient concentrations in a mesoscale mixed land cover watershed during base‐flow conditions. Factors that affect instream biological components, based on the Index of Biotic Integrity (IBI), were also analyzed. Seasonal BRT models at two spatial scales (watershed and riparian buffered area [RBA]) for nitrite‐nitrate (NO2‐NO3), total Kjeldahl nitrogen, and total phosphorus (TP) and annual models for the IBI score were developed. Two primary factors — location within the watershed (i.e., geographic position, stream order, and distance to a downstream confluence) and percentage of urban land cover (both scales) — emerged as important predictor variables. Latitude and longitude interacted with other factors to explain the variability in summer NO2‐NO3 concentrations and IBI scores. BRT results also suggested that location might be associated with indicators of sources (e.g., land cover), runoff potential (e.g., soil and topographic factors), and processes not easily represented by spatial data indicators. Runoff indicators (e.g., Hydrological Soil Group D and Topographic Wetness Indices) explained a substantial portion of the variability in nutrient concentrations as did point sources for TP in the summer months. The results from our BRT approach can help prioritize areas for nutrient management in mixed‐use and heavily impacted watersheds.  相似文献   

3.
承德市环境空气质量现状及对策   总被引:1,自引:0,他引:1  
2003承德市空气主要污染物与2002的相比,只有SO2年均值有所增大.运用Spearman-rs秩相关系数法预测该市空气质量有好转趋势,并从城市的地理位置、卫生、交通等几方面分析其污染特征及原因,建议以行政力量为指导,提高公民环保意识,实施合理的环境规划,利用最佳实用的环保技术改善该市环境空气质量.  相似文献   

4.
怒江流域高山峡谷区域具有集边疆、山区、民族、贫困为一体的特征,是我国典型的欠发达地区.尽管目前怒江流域已经进入工业化初期的经济发展阶段,但是长期闭塞、贫困和工业基础薄弱使流域经济发展动力不足.怒江流域的发展要把握云南建设面向东南亚、南亚开放的重要桥头堡这一战略机遇,立足自身的资源优势,引进外界资本与技术,打造水能资源经济,培育生态服务产业,同时通过交通基础设施建设和人力资本的培育改善发展环境.  相似文献   

5.
Local topography significantly affects spatial variations of climatic variables and soil water movement in complex terrain. Therefore, the distribution and productivity of ecosystems are closely linked to topography. Using a coupled terrestrial carbon and hydrological model (BEPS-TerrainLab model), the topographic effects on the net primary productivity (NPP) are analyzed through four modelling experiments for a 5700 km(2) area in Baohe River basin, Shaanxi Province, northwest of China. The model was able to capture 81% of the variability in NPP estimated from tree rings, with a mean relative error of 3.1%. The average NPP in 2003 for the study area was 741 gCm(-2)yr(-1) from a model run including topographic effects on the distributions of climate variables and lateral flow of ground water. Topography has considerable effect on NPP, which peaks near 1350 m above the sea level. An elevation increase of 100 m above this level reduces the average annual NPP by about 25 gCm(-2). The terrain aspect gives rise to a NPP change of 5% for forests located below 1900 m as a result of its influence on incident solar radiation. For the whole study area, a simulation totally excluding topographic effects on the distributions of climatic variables and ground water movement overestimated the average NPP by 5%.  相似文献   

6.
Recent studies of topographic disorientation from brain injury have focused on describing impairments, detailing neuroanatomical correlates of topographic disorientation, and classifying types of topographic disorientation. Normative models of environmental cognition have been applied in some studies of topographic disorientation, but more work is needed in this area. Few studies have produced data on everyday functioning with topographic disorientation. This paper presents data on compensatory wayfinding behavior in familiar environments, collected through case studies of three individuals with topographic disorientation from brain injury. Structured tests were used to evaluate visuo-spatial impairment, and normative models of wayfinding guided semi-structured and open-ended questioning about wayfinding inside and outside the home. All three-study informants were able to wayfind successfully within the home, though they varied in their ability to travel independently outside the home. Landmarks and scanning were important for orienting for all three subjects. The two subjects who were most able to travel independently also used sequencing of landmarks, directional heading and body position as elements of their wayfinding strategies. The information presented in this paper may prove useful to rehabilitation specialists who are treating brain-injured patients by providing new ideas about methods of compensation, and may contribute to emerging theory regarding impairments of orientation, and normative models of wayfinding.  相似文献   

7.
在分散成若干片区、地形复杂的工业城市进行空气监测优化布设时,应先确定测点所在的片区。优化时必须考虑地形和气象特点、污染源的分布和片区的功能特征。再根据片区内主要污染物及源分布确定决策团子。优化时再考虑片区内的污染气象条件,采用适当的空气扩散模式和动态模拟的方法。经过夏、秋两季实测结果证明,优化的测点代表性良好。  相似文献   

8.
Topographic Effects on Soil Organic Carbon in Louisiana Watersheds   总被引:2,自引:0,他引:2  
Terrestrial carbon storage is influenced by a number of environmental factors, among which topographic and geomorphological features are of special significance. This study was designed to examine the relationships of soil organic carbon (SOC) density to various terrain parameters and watershed characteristics across Louisiana, USA. A polygon data set of 484 watersheds and 12 river drainage basins for Louisiana was used to form the landscape units. SOC densities were calculated for each soil map unit using the State Soil Geographic (STATSGO) database. Average drainage densities and average slopes at watershed and basin scales were quantified with the 1:24 K Digital Elevation Models (DEM) data, and the Louisiana hydrographic water features. Correlation and regression analyses were performed to determine relationships among drainage density, slope, elevation, and SOC. The study found an average watershed drainage density of 1.6 km/km2 and an average watershed slope of 2.9 degrees in Louisiana. The results revealed that SOC density at both watershed and basin scales was closely related to drainage density, slope, and elevation. SOC density was positively correlated with watershed drainage density, but negatively correlated with watershed slope gradient and elevation. Regression models were developed for predicting SOC density at watershed and basin scales, obtaining regression coefficients (r 2) ranging from 0.43 to 0.83. The study showed that estimation of SOC at watershed and drainage basin scales combining DEM data can be a feasible approach to improve the understanding of the relationships among SOC, topographic, and geomorphological features.  相似文献   

9.
中国是造纸大国,制浆造纸在中国属于重污染行业。2008年国家发布的《制浆造纸工业水污染物排放标准》对整个行业可能排放的污染物提出了要求。本文通过将该标准与国外造纸行业相关的水污染物排放标准进行比较研究,找出我国标准与国外的差别,并为完善我国造纸行业水污染物排放标准提出建议。  相似文献   

10.
Potable and equitable drinking water (DW) is a fundamental human right and essential for human health. This study is conducted to assess the groundwater and jar water quality of the roadside restaurants and tea stalls used for drinking by the local people around the Gazipur City area in Bangladesh. Water samples from 173 restaurants and tea stalls are collected. The physico-chemical and biological parameters are analyzed according to the guidelines and standards. The results illustrate that the color, EC, and Mn of 41%, 80%, and 62% of the samples, respectively, exceed the WHO and Environmental Conservation Rules (ECR) standards. In addition, E. coli and total coliform exceeding the threshold standards are found in 47% and 64% of the water samples, respectively. The contamination of DW by fecal coliforms is confirmed and supported by prior studies, which indicates that the DW supplied in restaurants and tea stalls are unsafe because of the possible presence of pathogens. These may cause potential health hazards to consumers from various water-borne diseases. Poor sanitation, unhygienic practices, and improper disposal of wastewater are responsible for the microbial contamination of DW. So, the authorities in charge of these places should take the right regulatory steps, such as regular sanitation inspections, DW quality monitoring, hand-washing practices, and better sanitation in these places.  相似文献   

11.
We developed Columbia River streamflow reconstructions using a network of existing, new, and updated tree‐ring records sensitive to the main climatic factors governing discharge. Reconstruction quality is enhanced by incorporating tree‐ring chronologies where high snowpack limits growth, which better represent the contribution of cool‐season precipitation to flow than chronologies from trees positively sensitive to hydroclimate alone. The best performing reconstruction (back to 1609 CE) explains 59% of the historical variability and the longest reconstruction (back to 1502 CE) explains 52% of the variability. Droughts similar to the high‐intensity, long‐duration low flows observed during the 1920s and 1940s are rare, but occurred in the early 1500s and 1630s‐1640s. The lowest Columbia flow events appear to be reflected in chronologies both positively and negatively related to streamflow, implying low snowpack and possibly low warm‐season precipitation. High flows of magnitudes observed in the instrumental record appear to have been relatively common, and high flows from the 1680s to 1740s exceeded the magnitude and duration of observed wet periods in the late‐19th and 20th Century. Comparisons between the Columbia River reconstructions and future projections of streamflow derived from global climate and hydrologic models show the potential for increased hydrologic variability, which could present challenges for managing water in the face of competing demands.  相似文献   

12.
利用长沙市城区2011年及2012年连续自动监测获得的CO2数据,两年的平均值为412.2×10^-6,高于世界本底站青海瓦里关5.6%,与临安、无锡相当,略高于乌鲁木齐,而低于北京、上海。冬季CO2浓度日小时变化呈现双峰形态,峰值出现在上午9时及晚上19时~21时。夏季日小时变化为单峰形态,峰值出现在上午8时。冬季CO2浓度日均值为420.3×10^-6,比夏季高3.4%。CO2除与O3呈负相关以外,与其它污染物均呈现显著性正相关,特别是与CO、NO、NO2、NOx、SO2的相关性最强,而与颗粒物(PM10、PM25)的相关性稍差。  相似文献   

13.
To devise and implement strategies to manage the quality of urban air, a metropolis needs air pollution data on which an air quality management plan can be formulated. Although air pollutants can come from several sources, many reports suggest that nitrogen dioxide from motor vehicle emissions is the major contributor to air pollution in cities. Since vehicles stop or move slowly through traffic intersections, concentrations of nitrogen dioxide (NO(2)) are expected to be relatively high at these sites. Inexpensive Ogawa passive samplers were placed at selected traffic intersections in the Durban Metropolis to trap the NO(2) which was then analysed by a sensitive laboratory-based method. The data obtained by this method was compared with data from sophisticated system comprising an active sampler cum on-line chemiluminescence detector. The sampling was done over a twelve month period to cover all seasons. Statistical analysis of the data showed that there was no significant difference between the means for the two methods. This study has established that an Ogawa passive sampler may be used as an economical and reliable collector for NO(2) in ambient air under varying climatic conditions. Further, the analysis method using a UV-Visible spectrophotometer was sensitive enough to detect NO(2) at the 10-20 ppb level. The cost of the method should be well within the budgets of most municipalities and it would motivate them to develop policies to alleviate traffic congestion.  相似文献   

14.
Coastal ecosystems are dependent on terrestrial freshwater export which is affected by both climate trends and natural climate variability. However, the relative role of these factors is not clear. Here, both climate trends and internal climate variabilities at different time scales are related to variations in terrestrial freshwater export into the eastern United States (U.S.) coastal region. For the recent 35‐year period, the intensified hydro‐meteorological processes (annual precipitation or evapotranspiration) may explain the observed streamflow variability in the northeast. However, in the southeast, streamflow is positively correlated with climate variability induced by the Pacific Ocean conditions (El Nino‐Southern Oscillation [ENSO] and Pacific Decadal Oscillation) rather than Atlantic Ocean conditions (Atlantic Multi‐decadal Oscillation and North Atlantic Oscillation). The centroid location for volume of terrestrial freshwater export integrated along the eastern U.S. has a positive temporal trend and is negatively correlated with ENSO conditions, suggesting the northward trend in freshwater export to U.S. eastern coast may be disturbed by the natural climate variability, especially ENSO conditions, i.e., the center of freshwater mass moves southward (northward) during El Nino (La Nina) years. The results indicate the spatial and temporal variations in freshwater export from the eastern U.S. are affected by both climate change and inter‐annual climate variability during the recent 35‐year period (1980‐2014).  相似文献   

15.
The aim of the present study is to estimate the changes in cell hydration in different conditions using impedance measurements. Experiments were performed on adult and young male albino rats. Tissue hydration level was estimated as a difference between tissue wet and dry weight. Ouabain concentrations from 10−11 to 10−4 M, physiological solution (PS), mannit and distillated water (DW) were used. The impedance measurements were taken with “Biophys-Expert-1”. The increase in water content in the brain cortex (through the injection) raises the active conductivity after intraperitoneally injections of PS, mannit and DW. The more pronounced increase was observed in case of DW injection. The values of reactive conductivity were higher when mannit injection was made. In case of different ouabain concentrations, the active and reactive components were higher in young animals than in adult ones. Considering obtained results, the impedance measurement can be provided as a method for the estimation of tissue hydration level.  相似文献   

16.
Polluting substances are spread as a consequence of the construction and use of roads. This article provides a summary of the substances with which traffic pollutes the environment on a local, regional and global level. The mechanisms of dispersion of pollutants to soil and groundwater are described. Based on environmental quality requirements established in rules and regulations in the Netherlands, the paper discusses mitigating measures necessary to limit the distribution of pollutants along highways. Most of the data in this article come from original research carried out by or by order of the Road and Hydraulic Institute. For comparison, other data from the Netherlands have been included. It is shown that source-oriented measures (volume and technical) will have more effect on environmental quality than measures with regard to treating runoff. The use of porous asphalt instead of nonporous asphalt on highways in the Netherlands has environmental benefits. The article also pays attention to combined use of the roadside verges for treatment of runoff using ecological engineering techniques in the form of natural processes in helophyte filter systems in combination with enhancement of ecological values along highways.  相似文献   

17.
Chromophoric dissolved organic matter (CDOM) leached from leaf litter is a major source of humus in mineral soil of forest ecosystems. While their functions and refractoriness depend on the physicochemical structure, there is little information on the quality of CDOM, especially for that leached in the very early stages of litter decomposition when a large amount of dissolved organic matter (DOM) is leached. This study aimed to better understand the variations/changes in the composition of CDOM leached from senescent leaf litter from two tree species during the early stage of decomposition. Leaf litter from a conifer tree (Japanese cedar, D. Don) and a deciduous broad-leaved tree (Konara oak, Thunb.) were incubated in columns using simulated rainfall events periodically for a total of 300 d at 20°C. The quality of CDOM was investigated based on the fluorescence properties by using a combination of excitation-emission matrix fluorescence (EEM) and parallel factor analysis (PARAFAC). In addition, the phenolic composition of DOM was investigated at a molecular level by thermally assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH). The EEM was statistically decomposed into eight fluorescence components (two tannin/peptide-like peaks, one protein-like peak, and five humic-like peaks). A significant contribution of tannin/peptide-like peaks was observed at the beginning of incubation, but these peaks decreased quickly and humic-like peaks increased within 1 mo of incubation. The composition of humic-like peaks was different between tree species and changed over the incubation period. Since tannin-derived phenolic compounds were detected in the DOM collected after 254 d of incubation on THM-GC-MS, it was suggested that tannins partially changed its structure, forming various humic-like peaks during the early decomposition.  相似文献   

18.
This paper presents an analysis of the main environmental impact factors (noise, vibration, fumes, dust, vehicle traffic) associated with marble quarrying and processing in the Orosei industrial area and their effects. Solutions are also proposed to prevent, mitigate and, where possible, eliminate the impact on the environment. Using three-dimensional topographic models, the authors simulated quarry and industrial processing development, with projections over the next 10, 30 and 50 years. The aim of these simulations was to establish land management planning guidelines for the optimal and environmentally sustainable development of the Orosei Marble industrial area. Lastly, careful quarry development planning is important both for enhancing LCA and for improving production processes through sustainable technologies that yield green label products meeting environmental performance standards.  相似文献   

19.
We combined a natural experiment with field surveys and GIS to investigate the effects of dust from recreational trails and access roads on the federally threatened Valley elderberry longhorn beetle (“VELB,” Desmocerus californicus dimorphus) and its host plant, elderberry (Sambucus mexicana). Dust is listed in the species recovery plan as a threat to the VELB and unpaved surfaces are common throughout the riparian corridors where the VELB lives, yet the effects of dust on the VELB have been untested. We found that dust deposition varied among sites and was highest within 10 m of trails and roads, but was similar adjacent to dirt and paved surfaces within sites. Elderberry density did not differ with distance from dirt surfaces. Despite similar within-site dust levels, elderberry adjacent to paved surfaces were less stressed than those near dirt ones, possibly because increased runoff from paved surfaces benefited elderberry. Dust deposition across sites was weakly correlated with elderberry stress symptoms (e.g., water stress, dead stems, smaller leaves), indicating that ambient dust (or unmeasured correlates) influenced elderberry. Direct studies of the VELB showed that its distribution was not negatively affected by the proximity to dirt surfaces. Dust from low traffic dirt and paved access roads and trails, therefore, affected VELB presence neither directly nor indirectly through changed elderberry condition. These results suggest that the placement of VELB mitigation, restoration, and conservation areas can proceed independently of access roads if dust and traffic levels do not exceed those in our study site. Furthermore, dust control measures are likely to be unnecessary under such conditions. The potential effects of increased traffic and dust levels are addressed through a literature review.  相似文献   

20.
This paper examines predictors of vegetative cover on private lands in Baltimore, Maryland. Using high-resolution spatial data, we generated two measures: “possible stewardship,” which is the proportion of private land that does not have built structures on it and hence has the possibility of supporting vegetation, and “realized stewardship,” which is the proportion of possible stewardship land upon which vegetation is growing. These measures were calculated at the parcel level and averaged by US Census block group. Realized stewardship was further defined by proportion of tree canopy and grass. Expenditures on yard supplies and services, available by block group, were used to help understand where vegetation condition appears to be the result of current activity, past legacies, or abandonment. PRIZM™ market segmentation data were tested as categorical predictors of possible and realized stewardship and yard expenditures. PRIZM™ segmentations are hierarchically clustered into 5, 15, and 62 categories, which correspond to population density, social stratification (income and education), and lifestyle clusters, respectively. We found that PRIZM 15 best predicted variation in possible stewardship and PRIZM 62 best predicted variation in realized stewardship. These results were further analyzed by regressing each dependent variable against a set of continuous variables reflective of each of the three PRIZM groupings. Housing age, vacancy, and population density were found to be critical determinants of both stewardship metrics. A number of lifestyle factors, such as average family size, marriage rates, and percentage of single-family detached homes, were strongly related to realized stewardship. The percentage of African Americans by block group was positively related to realized stewardship but negatively related to yard expenditures.  相似文献   

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