Recent sudden decrease of lead in Adriatic coastal seawater during the years 2000–2004 in parallel with the phasing out of leaded gasoline in Italy

In parallel with the process of lead removal from gasoline in Italy, a research programme was undertaken to study the lead content of Adriatic coastal seawater. In the period 2000–2004 seawater was collected systematically at three sites along the coast line close to the city of Ancona: (i) the mouth of the River Esino, (ii) an area close to the Api refinery and (iii) Portonovo beach, a less impacted zone located along the coast of Mt. Conero. All samples were analyzed by Square-Wave Anodic-Stripping Voltammetry (SWASV). The results show that dissolved Pb content in coastal seawater diminished from an overall median value of 0.25 nmol/L in 2000–2001 to 0.12 nmol/L in 2003–2004, with a decrease of about 50% (statistically significant at 95% significance level). This decrease has been correlated to the concurrent decrease of lead consumption in gasoline in Italy which led to a reduction of ~ 65% Pb emissions into the atmosphere in the same period (r = 0.8791, p < 0.05).     

Extraction and motion estimation of vehicles in single-pass airborne LiDAR data towards urban traffic analysis

Airborne LiDAR data are characterized by involving not only rich spatial but also temporal information. It is possible to extract vehicles with motion artifacts from single-pass airborne LiDAR data, based on which the motion state and velocity of vehicles can be identified and derived. In this paper, a complete strategy for urban traffic analysis using airborne LiDAR data is presented. An adaptive 3D segmentation method is presented to facilitate the task of vehicle extraction. The method features an ability to detect local arbitrary modes at multi scales, thereby making it particularly appropriate for partitioning complex point cloud data. Vehicle objects are then extracted by a binary classification using object-based features. Furthermore, the motion analysis for extracted vehicles is performed to distinguish between moving and stationary ones. Finally, the velocity is estimated for moving vehicles. The applicability and efficiency of the presented strategy is demonstrated and evaluated on three ALS datasets acquired for the propose of city mapping, where up to 87% of vehicles have been extracted and up to 83% of moving traffic can be recovered together with reasonable velocity estimates. It can be concluded that airborne LiDAR data can provide value-added products for traffic monitoring applications, including vehicle counts, location and velocity, along with traditional products such as building models, DEMs and vegetation models.     

Vessel traffic patterns in the Port of Kaohsiung and the management implications for preventing the introduction of non-indigenous aquatic species

Data on shipping traffic in one of the busiest seaports in the world, the Port of Kaohsiung, were analyzed to evaluate the implications for ballast water management. Results show that 67% of the arriving vessels were registered to a flag of convenience, which typically have a lower degree of environmental records. The top five donor countries historically suffer from harmful algal bloom problems. The short journey and busy trading between these countries and Taiwan lead to a higher risk of inoculation. In addition, only 1.4% of all vessels visited more than once every year during the 9-year span, indicating that the port authority encounters many new vessels each year. These findings could influence the design and application of ballast water management strategies as well as highlight the challenges in their implementation. We suggest that an analysis of vessel traffic patterns should be coupled with other useful vessel information to make risk assessment successful.     

Lead isotopes as tracers of anthropogenic pollution in urban topsoils of Mexico City

A survey was performed to trace the main source of anthropogenic Pb pollution in Mexico City through Pb isotopic signatures (²⁰⁸Pb/²⁰⁴Pb, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁶Pb/²⁰⁷Pb, and ²⁰⁸Pb/²⁰⁷Pb) from 103 urban topsoil (0–5 cm) samples. Those were collected in the metropolitan area of Mexico City and compared with isotopic compositions of leaded gasoline (LG), domestic Pb ores (DLO) and parent rock (PR). The isotope ratios (IRs) of Pb were determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and total Pb concentration analyzed by wavelength dispersive X-ray fluorescence (WDXRF). The range of Pb concentrations levels in urban topsoil samples was 15–473 mg/kg. The IR values obtained for these samples were 37.965–39.718 (²⁰⁸Pb/²⁰⁴Pb), 18.375–19.204 (²⁰⁶Pb/²⁰⁴Pb), 1.177–1.218 (²⁰⁶Pb/²⁰⁷Pb) and 2.443–2.496 (²⁰⁸Pb/²⁰⁷Pb). Analyzed topsoil samples with low Pb content (<50 mg/kg) displayed high dispersion in ²⁰⁸Pb/²⁰⁴Pb values, which are determined by different natural sources. Samples with 51–200 mg/kg Pb content, shown low dispersion that revealed the mixing between the natural Pb and anthropogenic Pb. The assessment of the IR values shown that, as Pb concentration increases, a trend toward gasoline IR data has been observed. The results obtained by this research suggest that although the use of leaded petrol had been banned in Mexico since 1997, the Pb pollution in the urban topsoils due to the historical use of Pb in petrol is still significant.     

“交通灯”系统及其在诱发地震监测中的应用

随着页岩气开采、地热能源开采、CO2封存和水库蓄水等工业活动的开展,由此产生的诱发地震危害问题日益严重。为了对诱发地震进行有效监测和管控,地震学家设计了"交通灯"系统,当地震活动达到一定阈值时,相关人员可根据系统警报及时采取应对措施,减轻地震灾害。本文调研了近年来多个国家的"交通灯"系统研究和应用进展,介绍了其发展历史、设置原理及应用案例。"交通灯"系统的发展和完善应综合考虑震级、震动强度、b值和断层分布,以及建筑结构、城镇距离、人口密度、公众反应等社会因素。同时,在诱发地震频发区域,应建设密集的专用监测台网,提高微震检测和定位能力,并引入模板匹配和人工智能等新的自动处理方法,及时产出高完备性、高精度的微震目录,对微震的时空演化进行有效监测,形成时效性较强的"交通灯"系统。     

The detection of roadside pollution of rapidly growing city in arid region using the magnetic proxies

This work is a complementary investigation to the earlier urban soil survey for a rapidly growing city of relatively high traffic density. Therefore, it aims to apply the environmental magnetism approach to assess the roadside pollution at a known polluted site. The used magnetic proxies are the initial magnetic susceptibility and saturation magnetization. The results prove the applicability of this method in detecting roadside pollution. The shape and magnitude of the magnetic signals was affected by the topography and prevailing wind direction that caused the magnetic peaks to be shifted accordingly. Particle size was found to affect the magnetic material content, where sand size (63–150 μm) bears the highest magnetic signals relative to smaller silt size (<63 μm). The magnetic anomalies coincided positively with heavy metal pollution in the studied site, which might indicate that the magnetic materials serve as an effective proxy for the metallic pollution (i.e., Fe, Ni, Pb, Cu, and Zn) originated mainly from vehicular sources.     

基于GIS和AI的城市区域内最佳路径算法研究

针对传统Dijkstra算法效率低的特点,从GIS和人工智能的角度提出了一种对传统Dijkstra算法进行优化的方式。首先根据城市交通网络的特点建立了交通网络拓扑图,提出了地名节点和交通节点的概念,并用合理的数据结构存储此交通网络,然后在此基础上使用一种新的启发函数以提高搜索效率,使优化过的Dijkstra算法能用于复杂的交通网络。     

Effects of accessibility and environmental health risk on housing prices: a case of Salt Lake County,Utah

While transportation infrastructure can increase housing price by improving accessibility to opportunities, it generates environmental health risks, such as noise and air pollution, which may have negative effects on housing price. However, the combined effects of accessibility and environmental health risk on housing price have not been well examined in the literature, especially in the auto-oriented urban context of the United States. In this study, we use assessed housing value data and the hedonic model to examine the single-family housing market's reaction to accessibility and environment health risks in Salt Lake County, a growing metropolitan area in Utah experiencing significant air pollution. Three regression models are employed with the consideration of spatial effects: ordinary least squares (OLS), spatial lag regression (SLR), and hierarchical linear modeling (HLM, or multilevel modeling/MLM). By controlling for the influences of structural attributes and socioeconomic conditions, we find that the negative impacts (traffic noise and air pollution) of transportation systems on single-family housing prices are greater than the positive impact (accessibility). Single-family residents in Salt Lake County are willing to pay more to reduce environmental health risks than to get better accessibility. These findings are different from what have been found in some dense and compact urban areas in the literature. These findings suggest that people's willingness to pay for minimizing environmental health risks varies across different urban contexts.     

基于Flex的广州大学城交通服务WebGIS设计

根据Flex技术体系与特点,分析了构建基于Flex的WebGIS软件的系统结构,并阐述了Flex在WebGIS设计中的优势所在。利用ESRI公司的ArcGIS API for Flex开发包采用ASP.NET后台技术,设计并实现了广州大学城交通服务WebGIS系统。结果表明,使用Flex能够有效提高WebGIS客户端的交互能力,极大地提升了交通服务管理水平与效率,但是ArcGIS API for Flex开发包仍然存在一些不足,例如前后端通讯表现不足以及查询功能较弱等。     

Levels and distributions of organic source tracers in air and roadside dust particles of Kuala Lumpur,Malaysia

The concentrations of n-alkanes, unresolved complex mixture (UCM), petroleum molecular markers, other tracers of cooking and burning emissions, and natural background in atmospheric particles and roadside dust particles were measured at eight locations in the city center and the suburbs of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume filtration (PM-10, GFF) over 24 h average periods. Road dusts were swept up, dried and sieved. Both types of samples were extracted with dichloromethane/methanol mixture (3:1 v/v) by ultrasonic agitation. The extracts were then fractionated by column chromatography and the alkanes subjected to gas chromatography–mass spectrometry (GC–MS). Total extracts were also analyzed directly by GC–MS after silylation. The molecular distributions of compounds as well as diagnostic geochemical ratios were determined in order to identify the sources of the organic compounds. Samples collected from a rural area and lubricating oils were also analyzed for comparisons. Anthropogenic and biogenic sources such as vehicular emissions, waxes of higher plants, food cooking operations, and biomass and domestic refuse burning processes contributed to the organic matter content of atmospheric and to lesser extent, roadside dust particles.