The Effect of Traffic Density on Lead Contents in Roadside Soils: An Analysis of Published Data

Data from eight published studies were combined to show that the influence of traffic density on Pb contents in roadside soils increases with proximity to the road.     

城市行道树对交通环境的响应

以远离交通环境的公园作为相对清洁区,研究了位于广东佛山种植最普遍的8种城市行道树树黄葛榕(FicusvirensAit.var.sublanceolata(Miq.)Corner),大叶紫薇(Lagerstroemiaspeciosa(L.)Pers.),芒果(MangiferaindicaL.),细叶榕(FicusmicrocarpaL.),阴香(Cinnamomumburmanii(Nees)Bl.),垂叶榕(FicusbenjaminaL.),白兰(MicheliaalbaDC.),红花羊蹄甲(BauhiniablakeanaDunn)在交通密集区生长在不同方位的植物器官对交通环境的响应。结果表明,交通密集区的城市行道树的叶片和树皮器官吸收重金属铅和镉、硫含量、电导率和pH值等指标在不同的方位呈现显著的差别,即城市行道树位于快车道一侧生长的植物的器官(以下简称P1)、位于面向人行道一侧生长的植物的器官(以下简称P2)及相对清洁区采集的植物样品(以下简称P0)各指标测定值的分析结果为:其叶片和树皮硫、重金属铅和镉、电导率等特征值基本呈现P1>P2>P0的大小规律,在显著度为0.05时差异显著;而pH值基本呈现P1相似文献   

街谷绿化消减机动车排放污染物的研究方法与进展

随着街道两侧建筑群向高密度、高层化发展,传统“树越多越好”的绿化模式在应对城市街谷空气污染时是否适用受到广泛关注。明晰街谷绿化植物特征及其种植设计模式对机动车排放污染物消减的调控机理是发挥其提升街谷空气品质的重要前提。本文通过对近年国内外相关文献的梳理,比较分析了现场观测、风洞试验和数值模拟3种研究方法的适用性及局限性,详细剖析了行道树、绿篱两类绿化模式对街谷空气污染物扩散与沉降的影响机制,提出了一套面向空气质量提升的街谷绿化适应性设计工作框架。最后,分别从典型街谷绿化设计图示语言研制、街谷空气污染暴露评估技术指南编制、计算机流体力学模型中街谷绿化效应物理过程参数化方案优化等方面进行探讨,以期为后续研究提供思路和借鉴。     

Roadside Reclamation Outside the Revegetation Season: Management Options under Schedule Pressure

Roadside reclamation involves standard revegetation practices that often fail under the adverse conditions imposed by subordination to the infrastructure construction schedule. We experimentally tested for seed and microsite limitations on roadslopes by assessing the effects of seed addition and habitat suitability upon plant cover and species richness. The relative contributions of topsoil seed bank, seed rain, and hydroseeding with standard or native seed mixtures were analyzed in relation to soil texture, fertility, and stability. In order to increase applicability, this research was fitted into the actual construction design and schedule of a highway in central Spain, which resulted in topsoil of varying quality, steep roadcuts and embankments (34°), and out‐of‐season hydroseedings. During the first 2 years following roadslope construction, there was an uneven but sustained increase in plant cover and species richness. Topsoil spread on embankments led to greater plant cover in a shorter time and to lower sedimentation rates at slope bases. The topsoil seed bank was extremely poor. Hydroseeding invariably failed, regardless of seed mixture and roadslope type. The seed rain provided seven times more seeds than hydroseedings, and was correlated with the distance to vegetation patches. Recruitment, however, was limited by microsite suitability, as the initial soil content in nitrate, total nitrogen, and organic matter explained up to 80% of variation in plant cover. In conclusion, when revegetation was performed outside the optimal season due to schedule constraints, measures aimed at overcoming microsite limitation were more cost‐effective and enhanced roadside carrying capacity for local species.     

Lead and Cadmium Contamination in Roadside Soils in Irbid City,Jordan: A Case Study

This study evaluates the amount and distribution of Pb and Cd in roadside soils adjacent to two main roads in Irbid, Jordan, from October 2001 to July 2002. A total of 260 samples were collected from Irbid-Howara Street and Yarmouk University Street. Lead and Cd content were measured using Graphite Furnace Atomic Absorption Spectrometry. The environmental significance of this study is discussed in terms of the influence of traffic density on Pb and Cd concentrations in roadside soils, and enrichment factors were calculated to evaluate the degree of pollution. The accuracy of the results obtained has been examined and two standard reference materials, CRM 142 R (soil) and SRM 2709 (soil), were analyzed to confirm the accuracy of the results. The precision of the measurements was assessed in terms of relative standard deviation (RSD) using five replicate analyses of samples collected from the roadside sites. RSD values for Pb and Cd were found to be less than 6%. The overall Pb concentration in roadside soil samples was 325 and 431 μg g^?1 for Pb and 1.142 and 1.135 μg g^?1 for Cd in Yarmouk University Street and Irbid-Houwa Street, respectively. Results indicated that levels of Pb and Cd were decreasing as the distance from the road increases. Enrichment factor results were 655 and 826 for Pb, and 252 and 237 for Cd in Yarmouk University Street and Irbid-Houwa Street, respectively.     

Estimating Detection Probabilities of Waterfowl Broods From Ground-Based Surveys

ABSTRACT Brood:pair ratios could provide an economical method for assessing spatial or temporal variation in waterfowl productivity, but such estimators are severely biased by incomplete detection of broods. We conducted 3 sequential counts of 1,357 waterfowl broods in northeastern North Dakota, USA, and used closed-population mark-recapture models to estimate total brood abundance while controlling for variation in detection probabilities (p). Blue-winged teal (Anas discors) broods had the lowest average detection probability (p = 0.305), whereas diving-duck broods had the highest average detectability (p = 0.571). Detection was generally highest in morning or evening, but temporal patterns varied among species and there was no survey window that maximized detection probabilities for all species. Detection probabilities averaged 0.108 (SD = 0.056) higher for an experienced observer versus an inexperienced observer. Detection probabilities were 0.044 higher for roadside versus walk-up surveys and increased with increasing brood size, total brood abundance, survey date, wind speed, temperature, cloud cover, and amount of time spent surveying each wetland. Detection probabilities declined with increasing wetland size and amount of tall peripheral vegetation. Our mark-recapture results indicated that a traditional unreplicated brood survey would have missed 67.5% of estimated broods, summed over all species. Use of closed-population mark-recapture techniques provided an effective method for reducing this bias and identifying and quantifying factors that reduce detection probabilities of waterfowl broods. We recommend that future brood surveys incorporate 2 or 3 temporally segregated replicate counts to allow for formal estimation of detection probabilities.     

干旱河谷微生境变化对乡土植物幼苗定植的影响

干旱区植被斑块状分布格局引起的微生境差异对植被更新影响显著。气候变化和人类活动扰动下, 干旱区生态系统微生境多样化, 急需揭示乡土植物定植对不同微生境斑块变化的响应及其种间差异性, 并采用微生境调控技术促进退化生态系统植被恢复。该研究选择岷江干旱河谷区自然分布的灌木、半灌木和裸地微生境斑块, 采用移栽鞍叶羊蹄甲(Bauhinia brachycarpa)幼苗的试验方法, 揭示微生境变化对幼苗定植的影响; 进一步以极端退化的道路边坡为案例, 通过6种乡土植物种子直播试验探讨微生境调控技术及其对乡土植物幼苗定植的促进作用。结果显示, 在自然生态系统中, 裸地斑块上幼苗保存率和生物量显著大于植被斑块, 表明裸地微生境有利于幼苗定植; 养分添加仅对裸地斑块中幼苗生物量积累有促进作用。在裸地斑块中, 叶片生物量所占的比例和比叶面积较小, 相反根和茎生物量所占的比例较大。道路边坡上植被恢复试验结果显示, 6种乡土植物均能较好地适应土石混杂的边坡生境, 多数物种出苗率大于60%; 灌木幼苗保存率大于75%, 并且形成镶嵌式乡土灌草群落结构。地表覆盖和养分添加提高了边坡上种子出苗率和幼苗保存率, 促进了幼苗定植和结构稳定。该研究提供了有效促进工程边坡上乡土植物定植的方法, 可为干旱、半干旱生态系统退化荒坡和工程破坏地乡土植被恢复提供理论依据和技术指导。     

Uneven Rates of Landscape Change as a Source of Bias in Roadside Wildlife Surveys

ABSTRACT Roadside survey data have been used frequently to assess species occurrence and population trends and to establish conservation priorities. However, most studies using such data assume that samples are representative of either the amount of habitat or its rate of change at larger spatial scales. We tested both of these assumptions for the Breeding Bird Survey (BBS) from 1974 to 2001 in New Brunswick, Canada. Our study focused on mature forest—a cover type that we predicted would be characterized by rapid change due to human activities and that is of high ecological importance. We also sought to determine whether land cover changes adjacent to BBS routes were related to bird population trends detected in BBS data. Within all 3 time periods examined (1970s, 1980s, and 1990s), the amount of mature forest adjacent to BBS routes was significantly lower than in surrounding 1° blocks of latitude and longitude. This could be problematic for studies that use roadside data to compare the relative abundance of species. On average, mature forest declined at a rate of-1.5% per year over the 28-year study period. We detected no significant difference in the rate of change between degree blocks and BBS routes over this time span. However, in the 1970s and 1980s, mature forest declined more rapidly in degree blocks (-2.7%/yr) than adjacent to BBS routes (-0.5/yr). We also found that the BBS trend for a mature forest-associated species, blackburnian warbler (Dendroica fusca), was correlated with the trend in mature forest along BBS routes. This, combined with slower rates of mature forest change along routes in the 1970s and 1980s, suggests that BBS data may have underestimated population declines during this period. It is important that research be conducted to test for potential biases in roadside surveys caused by uneven rates of landscape change, particularly in regions characterized by rapid habitat alteration.     

Emergency relocation of a Purple Copper Butterfly colony during roadworks: Successes and lessons learned

Summary  In 2004, the Roads and Traffic Authority (RTA) undertook a road realignment project near Lidsdale in the Central Tablelands of New South Wales. However, the RTA had not detected a population of the threatened Purple Copper Butterfly within the footprint of the project. The RTA responded promptly when notified of the butterflies' presence by stopping works, and preparing and implementing a butterfly management programme. This programme included modifying the realignment (and reducing the development footprint), supplementary planting of habitat, habitat rehabilitation and translocation of individual caterpillars from within the final footprint area. These actions seem to have safeguarded the population at least in the short term; however, further active management of the site will be needed to ensure its long-term viability. The project reinforces the importance of thorough predisturbance assessment of a site at the early planning stages, and the results and observations could be particularly informative in planning for introduction, reintroduction and translocation proposals involving the Purple Copper Butterfly.