ITS数据质量控制技术及应用研究

通过总结智能交通系统 (ITS)数据质量控制中所涉及的数据属性 ,提出了ITS数据质量控制算法 :根据阈值理论和交通流理论 ,针对错误数据、丢失数据和不精确数据设计相应的判别规则 ,利用数值计算方法对其进行修正 ,并提出了针对数据中的不规则时间点的修正算法。在对北京市和美国圣安东尼奥市的两组不同时间序列的ITS数据进行实践应用后 ,比较质量控制前后的数据特征 ,证明所提出的算法能够有效地解决数据质量问题 ,提高数据的精确度。最后 ,对国内外ITS数据进行质量控制后的结论和经验作了总结。     

Temporal variations of surface water quality in urban, suburban and rural areas during rapid urbanization in Shanghai, China

As the economic and financial center of China, Shanghai has experienced an extensive urban expansion since the early 1980s, with an attendant cost in environmental degradation. We use an integrated pollution index to study the temporal variations of surface water quality in urban, suburban and rural areas between 1982 and 2005. Data on monitored cross-sections were collected from the Shanghai Environmental Monitoring Center. The results indicated that the spatial pattern of surface water quality was determined by the level of urbanization. Surface water qualities in urban and suburban areas were improved by strengthening the environmental policies and management, but were worsening in rural areas. The relationship between economic growth and surface water quality in Shanghai showed an inversed-U-shaped curve, which reflected a similar pattern in most developed countries. This research suggests that decision makers and city officials should be more aware of the recent pollution increases in Shanghai.     

Temporal trends of polyfluoroalkyl compounds (PFCs) in liver tissue of grey seals (Halichoerus grypus) from the Baltic Sea, 1974-2008

Temporal trends of polyfluoroalkyl compounds (PFCs) were examined in grey seal (Halichoerus grypus) liver from the Baltic Sea over a period of 35 years (1974-2008). In total, 17 of 43 PFCs were found, including the perfluoroalkyl sulfonates (C₄-C₁₀ PFSAs), perfluorooctanesulfinate (PFOSi), long chain perfluoroalkyl carboxylates (C₇-C₁₄ PFCAs), and perfluoroalkyl sulfonamides (i.e., perfluorooctane sulfonamide (FOSA) and N-ethyl perfluorooctane sulfonamide (EtFOSA)), whereas saturated and unsaturated fluorotelomer carboxylates, shorter chain PFCAs and perfluoroalkyl phosphonic acids were not detected. Perfluorooctane sulfonate (PFOS) was the predominant compound (9.57-1444 ng g⁻¹ wet weight (ww)), followed by perfluorononanoate (PFNA, 0.47-109 ng g⁻¹ ww). C₆-C₈ PFSAs, PFOSi and C₇-C₁₃ PFCAs showed statistically significant increasing concentrations between 1974 and 1997, with a peak in 1997 and then decreased or levelled off (except for C₁₂ and C₁₃ PFCAs). FOSA had a different temporal trend with a maximum in 1989 followed by significant decreasing concentrations until 2008. Toxicological implications for grey seals are limited, but the maximal PFOS concentration found in this study was about 40 times lower than the predicted lowest observed effect concentrations (LOEC). The statistically significant decreasing concentrations or levelling off for several PFCs in the relative closed marine ecosystem of the Baltic Sea indicate a rapidly responding to reduced emissions to the marine environment. However, the high concentrations of PFOS and continuing increasing concentrations of the longer chain PFCAs (C₁₂-C₁₄) shows that further work on the reduction of environmental emissions of PFCs are necessary.     

Trends in Chemical Composition of Wet-only Precipitation at Rural French Monitoring Stations Over the 1990–2003 Period

The long-term monitoring of precipitation and its chemical composition are important for identifying trends in rain quality and for assessing the effectiveness of pollution control strategies. A statistical test has been used to the atmospheric concentrations measured in the French rural monitoring network (MERA) in order to bring out spatio-temporal trends in precipitation quality in France over the period 1990–2003. The non-parametric Mann–Kendall test which has been developed for detecting and estimating monotonic trends in the time series was used and applied in our study at annual values of wet-only precipitation concentrations. The emission data suggest that SO₂ and NO _x emissions decreased (−3.3 and −2.0% year⁻¹, respectively) contrary to NH₃ emissions that increased slightly (+0.2% year⁻¹) over the period 1990–2002 in France. On the national scale, the pH values have a significant decreasing trend of −0.025 ± 0.02 unit pH year⁻¹. and concentrations in precipitation have a significant decreasing trend, −3.0 ± 1.6 and −3.3 ± 0.6% year⁻¹, respectively, corresponding with the downward trends in SO₂ emissions in France (−3.3% year⁻¹). A good correlation (R ² = 0.84) between SO₂ emissions and concentrations was obtained. The decreasing trend of was more significant (−5.4 ± 5.2% year⁻¹) than that of (−1.3 ± 2.4% year⁻¹). Globally, the concentration of the major ions showed a clear downward trend including marine and alkaline ions. In addition, the relative contribution of HNO₃ to acidity precipitation increased by 51% over the studied period.     

Effects of Land Management Change on Spatial Variability of Organic Matter and Nutrients in Paddy Field: A Case Study of Pinghu,China

The Household Responsibility System initiated in the late 1970s in China has brought a profound change to its rural economy. The shift from the collective farming system to individual family farms has changed land management. The change, including fertilization and crop systems, may have significant effects on soil quality and agro-environmental sustainability. However, very little research is being carried out on the impact of reformed land tenure systems on the spatial variability of soil nutrients. In this study, geostatistics was applied to analyze changes in the spatial variability of soil organic matter and nutrients in paddy fields in Pinghu County, China after 20 years of land management change. In 1984 and 2002, 617 and 131 locations were selected, respectively, for collecting surface soil samples to analyze soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK). From 1984 to 2002, variability of the SOM and TN changed from strongly to moderately spatial-dependent, and the variability of AP remained weakly dependent on space, but that of the AK changed from moderately to weakly spatial-dependent. That the trend of the variability of four soil properties in 2002 became weaker than that in 1984 showed that the extrinsic factors (soil management practices, such as fertilization) weakened the effect by intrinsic factors (soil formation factors, such as soil parent materials) owing to a long period of land management change. The temporal geographic maps of the SOM and nutrients spatial distributions suggested that the concentrations of the SOM and nutrients had been changed to different extents during the period. Significant increase in AP and decrease in AK were noted. The changes were likely due to the imbalance between N, P, and K fertilizers and increased grain yield.     

Developing the scientific basis for assessing cumulative effects of wetland loss and degradation on landscape functions: Status,perspectives, and prospects

The incongruity between the regional and national scales at which wetland losses are occurring, and the project-specific scale at which wetlands are regulated and studied, has become obvious. This article presents a synthesis of recent efforts by the US Environmental Protection Agency and the Ecosystems Research Center at Cornell University to bring wetland science and regulation into alignment with the reality of the cumulative effects of wetland loss and degradation on entire landscapes and regions. The synthesis is drawn from the other articles in this volume, the workshop that initiated them, and the scientific literature. It summarizes the status of our present scientific understanding, discusses means by which to actualize the existing potential for matching the scales of research and regulation with the scales at which effects are observed, and provides guidelines for building a stronger scientific base for landscape-level assessments of cumulative effects. It also provides the outlines for a synoptic and qualitative approach to cumulative effects assessment based on a reexamination of the generic assessment framework we proposed elsewhere in this volume.The primary conclusion to be drawn from the articles and the workshop is that a sound scientific basis for regulation will not come merely from acquiring more information on more variables. It will come from recognizing that a perceptual shift to larger temporal, spatial, and organizational scales is overdue. The shift in scale will dictate different—not necessarily more—variables to be measured in future wetland research and considered in wetland regulation.     

General concepts for measuring cumulative impacts on wetland ecosystems

Because environmental impacts accumulate over space and time, analysis is difficult, and we must incorporate the most recent scientifically defensible information and methods into the process. Methods designed to deal specifically with cumulative impacts include checklists of characteristics or processes, matrices of interactions (rated according to their level of importance) between disturbance activities and environmental conditions, nodal networks or pathways that depict probable effects of disturbances, and dynamic system models. These methods have been tested over the past decade and have proven generally successful.Landscape perspectives have emerged as especially helpful in analyzing cumulative effects, and have focused specific attention on questions of spatial and temporal scale, while leading to recognition of the complexity of ecosystem processes in general. An evaluation of several cases studies by the Commission on Life Sciences of the U.S. National Academy of Sciences emphasizes the importance of interactions and cumulative effects, but recognizes that current knowledge of the processes involved is insufficient to make specific recommendations for conceptual frameworks.The conceptual approach suggested by Preston and Bedford (1988) addresses many critical issues, such as the need to define dimensions of scale, and the importance of wetland size, shape, and location in the landscape. This approach and similar ones must be tested and evaluated so that a consensus may eventually emerge.A cumulative impact matrix is proposed that sets up additive, synergistic, and indirect categories, each capable of variation in space and time. Every interaction would be carefully examined to determine the likelihood of cumulative impact in any of the six categories. Because of its magnifying glass approach, such a matrix could be a very useful analytical tool, using existing methods to uncover all the information presently available about the behavior of the ecosystem of concern.     

Temporal changes in the utilization of amniocentesis for prenatal diagnosis by women of advanced maternal age, 1976–1983

Utilization of amniocentesis for prenatal diagnosis because of the indication of advanced maternal age (≥ 35 years at delivery) was examined in the population of B.C. over an 8-year period (1976–1983). As of 1983, approximately one out of three eligible women (≥ 35 years at delivery) is having the test. In the older group (≥ 38 years at delivery) approximately one out of two eligible women is having the test. The data do not indicate that the proportion of eligible women having amniocentesis has reached a plateau; utilization is continuing to increase. It appears that prenatal diagnosis is an ethically acceptable alternative for a large proportion of the population.     

交通事故信息管理与时空分布分析

交通事故发生点具有明确的空间位置属性 ,其在空间和时间上的分布具有不均匀性 ,利用GIS技术能实现交通事故信息管理及其时空分布规律的研究。笔者在分析道路交通事故信息的基础上 ,采用全新的管理模式 ,利用空间数据库技术实现交通事故的空间、时间信息以及造成交通事故的人、车、路和环境等因素的一体化管理 ;通过GIS技术进行道路交通事故的时空分布分析 ,发现其在空间和时间上的分布规律 ;最后提出了交通事故管理与分析中需要进一步解决的几个问题。     

Temporal changes in demand for and supply of nests in red bishops (Euplectes orix): dynamics of a biological market

The red bishop (Euplectes orix) is a highly polygynous and colonial weaverbird. Males construct several nests within their territories to which they try to attract females, and females are solely responsible for incubation and raising offspring. In this paper, we describe the characteristics of the red bishop’s mating system as a biological market and investigate the role of nests built by males as a traded commodity in a mating market. As timing of breeding in red bishops in arid and semi-arid zones depends on rainfall patterns which are often unpredictable, there are temporal changes in demand for and supply of nests within a breeding season, with breeding activities of males and females being highly synchronised. We found that males increased their nest-building speed with increased female breeding activity independently of rainfall, indicating that supply follows demand in this mating market. The supply of nests was always larger than the demand for nests. Construction costs for nests increased with demand for nests as indicated by shorter nest-building duration and shorter building delays between two consecutively built nests at times of high breeding activity. Males as a trading class are chosen according to the age of their nests offered, with young nests having a higher probability of being accepted by females. Furthermore, female choosiness with regard to nest age decreased when their own market value decreased, as predicted by biological market theory. The temporal changes of breeding activity together with the female preference for young and fresh nests require that males quickly adjust nest-building activity to varying female demand for new nests. However, males with a better adjustment of building speed to female breeding activity did not gain higher mating success.