城市地表灰尘的概念、污染特征与环境效应

城市地表灰尘是重要的非点源污染之一,20世纪70年代就引起了国外学者的注意,研究成果颇丰,国内近年来虽然也取得了一些成果,但一直未能引起学术界的足够重视.本文从非点源污染研究的角度出发,对城市地表灰尘的概念提出了新的认识,并对国内外地表灰尘污染研究的发展阶段、研究现状等进行了系统的阐述与总结,提出了相应的研究重点及方向.城市地表灰尘是环境中污染物质的“源”、“汇”载体,包含特定的环境信息,对区域环境状况具有良好的指示作用.地表灰尘污染的研究应该成为我国城市生态环境研究的一个新的切入点,对城市生态和非点源污染管理有着重要的现实意义.     

城市地表径流污染来源的分类与特征

城市地表径流中污染物的分布和浓度等污染特征取决于其污染来源。本文依据3种分类方法分析了城市地表径流污染物的来源及其特征,重点讨论了城市地表径流中主要的污染物悬浮颗粒物、持久性有机污染物、农药、重金属、营养元素、有机质和其他有代表性的工业源化合物的来源、污染特征和生态风险等,介绍了城市地表径流对受纳水体的影响及其评价方法,并探讨了今后的研究重点。     

天津公园灰尘与土壤重金属污染特征

对天津市区41个代表性公园及滨海新区10个大型公园灰尘和土壤重金属理化性质及含量进行了测定,分析了灰尘和土壤中重金属的空间分布特征.结果表明:天津市公园灰尘和土壤粒径分布呈双峰或多峰分布特征;灰尘和土壤中有机质平均含量分别为49.10和27.15 g·kg-1.公园灰尘重金属Cu、Pb、Cr、Cd和Ni含量均值分别为113.88、76.81、141.53、1.30和114.70 mg·kg-1,土壤中则分别对应41.68、30.76、96.43、1.01和34.03 mg · kg-1,均高于天津市土壤背景值.天津和平区、南开区东北部与河西区所受重金属污染较小.相关分析与主成分分析表明,有机质是灰尘与土壤中重金属Cd的重要载体,包括交通流量、工业活动等在内的人为因素是公园灰尘、土壤重金属Cr、Ni、Cu、Pb的主要来源.     

天津城市公园灰尘重金属污染健康风险评价

分析了天津市中心城区41个代表性公园灰尘样品的重金属含量,借助健康风险评价模型,对天津市公园灰尘重金属的污染状况进行了健康风险评价。结果表明,天津市公园灰尘在不同程度上受到了重金属Cu、Pb、Cr、Cd和Ni的污染,其中,重金属Cu、Pb、Cr、Cd和Ni的含量平均值分别为113.18、63.32、103.18、1.14和40.58 mg·kg-1,均高于天津市土壤重金属元素的背景值。健康风险评价模型计算表明,人体经手-口接触行为直接摄入是公园灰尘暴露风险的主要途径,重金属日平均暴露剂量依次为手-口直接摄食剂量皮肤吸收剂量呼吸道吸入剂量。本研究的5种重金属元素对人体造成的慢性非致癌风险值依次表现为:CrPbCuNiCd,对人体不会造成危害,儿童的非致癌风险大于成人。致癌重金属的致癌风险依次为NiCrCd,均低于癌症风险阈值,尚未形成致癌风险。     

城市三维空间形态的热环境效应研究进展

城市的三维空间形态,通过影响地表能量平衡过程和空气流动,改变城市内部热环境,并可能加剧城市热岛效应。在三维空间上定量解析格局-过程-效应关系对于城市生态安全和可持续发展具有重要意义,可为城市生态规划与景观设计提供重要科学依据。从城市三维形态的热环境效应研究角度,综述了城市三维形态的定量化研究进展;总结了城市三维形态对热环境以及空气流动、太阳辐射等过程的影响;分析了当前城市三维形态的热环境效应研究领域存在的不足。未来的研究应注重建筑与植被三维特征的综合表征,三维形态指标的选择应综合考虑其对设计规划的指导作用,并加强城市三维形态对热环境影响机理及其尺度效应的研究。     

沈阳市住宅区小区与街道灰尘重金属污染评价

城市住宅区是人类活动的重要场所,与居民的日常生活紧密相关。为了解沈阳市住宅区小区与街道灰尘中重金属污染的空间分布,采集了不同住宅区小区与街道的灰尘样品,分析了灰尘中重金属的含量,并使用富集因子和地累积指数评估了其污染程度。结果表明,沈阳市灰尘中重金属Cr、Cd、Cu、Pb和Zn的平均含量均超过辽宁省表层土壤元素背景值。单因素方差分析表明,街道灰尘中重金属Cu、Fe、Mn和Zn的空间分布具有显著性差异,而小区灰尘中重金属Cd、Cr、Fe、Mn和Pb在空间上具有显著性差异。重金属Cd、Zn和Pb的平均污染水平较高,其中小区内Cd和Zn的污染程度高于街道。沈阳市不同方位住宅区灰尘中重金属的污染水平介于轻度污染至中度污染之间。     

新疆库尔勒市地表灰尘重金属污染及潜在生态风险

从库尔勒市采集54个地表灰尘样品,测定其中Hg、Cd、As、Pb、Cr与Cu共6种重金属元素含量,采用内梅罗综合污染指数(NPI)、潜在生态风险指数(HRI)和生态风险预警指数(IER),评价了地表灰尘重金属污染及潜在生态风险。结果表明,库尔勒市地表灰尘中Hg、Cd、Pb、Cr和Cu等元素含量平均值分别为新疆土壤背景值的3.71、1.87、1.96、1.14和1.29倍。其中,Hg呈现重度污染,Cd、Pb、Cr、Cu呈现轻度污染,As呈现轻微污染,NPI平均值呈现重度污染。潜在生态风险评价结果表明,地表灰尘中Hg呈现较强生态风险,Cd呈现中等生态风险,As、Pb、Cr和Cu呈现轻微生态风险,HRI平均值为232.23,呈现中等生态风险。根据生态风险预警分级标准,地表灰尘中Hg污染处于轻警态势,Cd、Pb、Cu和Cr污染处于预警态势,As污染处于无警态势,IER平均值为4.91,处于中警态势。从空间分布格局来看,地表灰尘重金属污染及生态风险高值区分布于研究区北部。总体上,库尔勒市地表灰尘重金属污染风险相对较低。     

上海城市热岛效应形成机制及空间格局

城市热岛效应的产生及演变与城市地表覆被变化、人类社会经济活动密切相关,是城市生态环境状况的综合概括与体现,目前对城市热岛形成、演变的驱动机制、热岛效应与地表覆被变化的定量关系研究大多还是从对某些影响因子的测定入手,缺乏对区域热环境系统全面、综合的评价与分析.近年来,在城市化过程中,人类社会、经济活动的加剧使城市地表热力景观呈现出高度的空间异质性,在利用Landsat 7 ETM+热波段数据反演上海地区地表温度的基础上,应用地统计学方法揭示了不同尺度下上海城市地表温度场空间变异特征及其不同的驱动因子.进而,采用决策树方法构造城市热环境系统的分类和预测模型,建立中心城区地表温度场空间分布及其驱动因素之间的定量关系,挖掘上海城市热岛效应的形成机制,揭示出多种影响因素综合作用下中心城区热环境空间格局差异.研究结果表明,城市热环境形成的驱动因子在空间上呈现出明显的分异性特征,各种影响因素在空间上不同的组合方式将决定城市热岛效应的时空演变趋势.运用决策树方法可以有效地确定在城市内部不同区域影响热环境形成的主导因素,揭示城市热岛形成与演变的成因机制及其空间差异,并可以进一步用来预测分析未来城市地表温度场动态变化的空间分布格局.     

城市公园景观的热环境效应

城市热环境受到地表的物理性质和人类社会经济活动的共同影响,是城市生态环境状况的综合体现.而城市公园景观的热环境效应显著区别于其它景观类型.城市公园景观的热环境效应研究对城市规划以及城市生态环境评价都具有重要意义.论文以上海市为例,首先提取了城市公园景观斑块的空间分布数据,再利用Landsat7的ETM 为基本数据源,定量反演了城市热环境温度,然后利用GIS中的空间分析功能,重点探讨了城市公园景观的热环境效应.公园景观斑块的面积、周长与其对应的温度具有负相关关系,而形状复杂性指数则与环境温度具有显著的正相关关系,形状复杂性指数则与环境温度的相关程度远高于面积、周长与热环境温度的相关程度.公园斑块的面积以及周长与公园对周围热环境的影响在统计上相关性较差;而形状复杂性指数则与其影响力则具有显著的正相关关系,形状越复杂,公园对周围热环境影响力越强.因此,在城市公园建设中,除了公园类型、空间选址外,边界形状也应作为考虑因素之一.     

山地城市坡向对地表温度的影响——以重庆市主城区为例

为揭示坡向对山地城市地表温度的影响,以重庆市主城区为例,由Landsat TM影像反演地表温度,提取各坡向上的地表温度,进行方差分析。结果发现,东南和南坡向的地表温度较高,而西北和北坡向的地表温度较低,8坡向分类时,各坡向的平均地表温度的差异具有显著性;用地类型没有坡向偏好,对于同一种用地类型,各坡向的平均地表温度没有显著差异。不同的用地类型上的城市建设强度和生产、生活活动差异是引起地表温度变化的主要因素,而坡向对城市地表温度的影响相比强烈的城市人为活动产生的环境效应而言是微弱的。     

北京城区行道树国槐叶面尘分布及重金属污染特征

叶面尘分布范围广、累积时间长,能够较好地指示近地面大气颗粒物污染特征和累积状况。为揭示城市道路交通的大气颗粒物污染特征,研究了北京城区不同类型道路两侧行道树国槐(Sophora japonica)的叶面滞尘量,分析了叶面尘主要重金属的浓度和污染特征,采用相关分析和主成分分析法探讨了颗粒物重金属的主要来源。结果表明:国槐叶面滞尘量在快速路、主干路、次干路、支路上的比值为100∶84∶75∶75,受车流量影响较大。行道树国槐的平均叶面滞尘量为0.68 g/m2,庭院树国槐(远离交通)叶面滞尘量是0.51 g/m2,两者差异显著。行道树叶面尘重金属元素Cu、Zn、Pb在叶面尘中的浓度达到土壤背景值的6倍,空间分布较均匀,主要来自交通排放,庭院树叶面尘重金属污染也受到交通排放的重要影响。     

工矿区不同类型生物结皮对大气降尘重金属的富集规律及其影响因子

大气降尘是矿区土壤重金属的主要来源,而生物结皮对大气降尘重金属有显著的富集作用。为探究不同类型生物结皮对大气降尘重金属的富集规律及其影响因子,选取宁东典型火电厂周边生物结皮广布区作为试验样地,3类生物结皮作为研究对象,并以临近裸土作为对照,对比分析了生物结皮富集大气降尘过程中土壤理化性质、酶活性及重金属含量的变化,采用相关分析、冗余分析和方差分解方法探讨了不同类型生物结皮的结皮层(A层)和层下土壤(B层)重金属含量与其土壤物理、化学性质及酶活性之间的关系。结果表明：燃煤烟尘是矿区大气降尘重金属污染的主要来源,涉及重金属元素包括Cd、Cr、Hg、Pb、Zn、As。生物结皮对源自大气降尘的重金属元素均具有显著的富集作用,且在不同演替阶段生物结皮间的富集规律完全一致：藓结皮>混生结皮>藻结皮;重金属综合污染指数评价结果显示：生物结皮对重金属具有表层富集效应,表现为A层污染程度高于B层。不同类型生物结皮A、B层综合污染指数存在显著差异,排序为：藓结皮>混生结皮>藻结皮;和对照相比,三类生物结皮均能通过富集大气降尘增加其A、B层养分和细颗粒物含量并改善土壤质地。方差分解结...     

Health risk assessment on heavy metals in urban street dust of Tianjin based on trapezoidal fuzzy numbers

The aims of this article were to investigate heavy metals concentrations in urban street dust of Tianjin, to examine spatial variations of heavy metals pollution, and to assess their health risk to local populations. Urban street dust samples were collected from 144 typical crossroads in an urban area of Tianjin. Levels of heavy metals were determined by atomic absorption spectrophotometer analyzer. Given comprehensive consideration of the complexity and uncertainty of health risk assessment, trapezoidal fuzzy number was introduced to assess the health risk of heavy metals in the urban street dust of Tianjin. The results showed that the pollution of heavy metals in the urban street dust of Tianjin was serious. The relatively serious metal pollution tended to be located in the center, north, northeast, and southeast of the study area. The research indicated that heavy metals in street dust had caused non-cancer hazard to children but had not caused non-cancer or cancer hazard to adults. The direct ingestion of dust via hand-mouth contact behaviors was the major exposure pathway for health risk.     

The Distribution of Heavy Metals in Urban Street Dusts of Karak City,Jordan

Street dust samples from urban and suburban areas were collected from the city of Karak, Jordan, during the summer season of 2004. Samples were analyzed for their heavy metal concentrations (Pb, Cu, Zn, Ni, Fe, Cr, Cd, and Mn). The results showed that all heavy metals are higher in city urban areas than the surrounding suburbs. The distribution and concentrations of heavy metals in all areas show automobile originated sources such as emissions and wear and tear of automobiles were the main source of pollution. Despite the fact that the city of Karak and the capital Amman are under the same climatic conditions and same type of fuel used in both cities, the heavy metal concentrations of street dust samples were lower in Karak than Amman due to the lower traffic density.     

Survey of atmospheric heavy metal deposition in Suqian using moss contamination

Abstract

Heavy metal pollution in the atmosphere is a major environmental problem, which has important impacts on ecosystems and human health. In this study, the atmospheric deposition of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in Suqian, China, was investigated by using the moss Haplocladium microphyllum as a bioindicator. The survey was carried out during the summer of 2017 at 40 homogenously distributed sampling sites. Cr, Cu, Ni, Pb, V, and Zn were analyzed by inductively coupled plasma atomic emission spectrometry, and Cd was analyzed by inductively coupled plasma mass spectrometry. Wide variations in heavy metals (Cd, Pb, and Zn) indicated that the concentrations of elements are influenced by local emission sources. Spatial distribution maps of the elements were constructed using geographic information system technology. The pollution load index showed that the study area was moderately polluted to unpolluted. Significant positive correlations (p?<?.01) and weak positive correlations (p?<?.05) were identified among some of the elements, indicating that they originated from common sources. A principal component analysis classified the heavy metals into natural and anthropogenic sources, and identified four primary sources: nature soil dust, industry activities, traffic emission, and agricultural activities.     

Assessment of heavy metal toxicity related with human health risk in the surface water of an industrialized area by a novel technique

This study innovates an assessment technique to evaluate heavy metal toxic load (HMTL). Assessment of surface water in Durgapur industrial area, West Bengal India illustrates that heavy metals in majority of sampling locations exceed the drinking water quality standards. Therefore, pollution status and health impact were predicted by heavy metal pollution index (HPI) and hazard index (HI). More than 50% of sampling locations were marked as polluted. Moreover, 5% and 90% of sampling locations near the industries have health risk to adult and child on ingestion. The study of specific exposure-time and exposure-duration affirms the suitability of water for fishing and regular activities. However, HPI or HI does not quantify heavy metal concentrations that pose threat to human health. Therefore, the proposed assessment technique, HMTL, determines the concentration of heavy metals responsible for health hazard. HMTL identifies Mn, Pb, and Co as toxic metals and estimates 85%, 63%, and 70% removal of these metals from surface water to limit pollution. Origins of metals were also investigated through statistical techniques, which revealed that Fe has geogenic and anthropogenic source, while other metals originate by anthropogenic activities solely. This study demonstrates that HMTL will help the planning authority to document effective water quality management plan.     

A Review on Heavy Metals Contamination in Soil: Effects,Sources, and Remediation Techniques

Soil heavy metal pollution has become a worldwide environmental issue that has attracted considerable public attention, largely from the increasing concern for the security of agricultural products. Heavy metals refer to some metals and metalloids possessing biological toxicity, such as cadmium, mercury, arsenic, lead, and chromium. These elements enter the soil agro-ecosystem through natural processes derived from parent materials, and through anthropogenic activities. Heavy metal pollution poses a great threat to the health and well-being of organisms and human beings due to potential accumulation risk through the food chain. Remediation using chemical, physical, and biological methods has been adopted to solve the problem. Phytoremediation has proven to be a promising alternative to conventional approaches as it is cost effective, environmentally friendly, and aesthetically pleasing. To date, based on the natural ability of extraction, approximately 500 taxa have been identified as hyperaccumulators of one or more metals. In addition, further research integrating biotechnological approaches with comprehensive multidisciplinary research is needed to improve plant tolerance and reduce the accumulation of toxic metals in soils. This review discusses harmful effects, sources of heavy metals, and the remediation technologies for soil contaminated by heavy metals.     

Risk Assessment of Heavy Metals in Street Dust Particles to a Stream Network

Runoff with contaminated urban soil has an environmental risk to the aquatic environment. An assessment of heavy metals in street dust particles from a small town and their risks to the township stream network were conducted at Yangtze River delta. This assessment is based on measurement of heavy metal contents in dust particles with different particle sizes, river sediments, and suspended solids of urban runoff. The ranges of heavy metal content were 0.8–4.3, 16–380, 69–240, 9.3–350, 9.6–863 and 67–1170 mg/kg dry street dust, for Cr, Cu, Ni, Pb and Zn, respectively. Approximately 63%-71% of heavy metals were associated with particles less than 250 μ m; this particle size accounted for 40% of the total mass of street dusts. Of the five land use areas, the industrial areas had the highest heavy metal level. The smaller particle size fraction has a higher heavy metal content, low density, high mobility in runoff, and thus is a higher risk to the stream network. The topographical and hydrological features of the landscape also influence the transport of the contaminated street dusts to the aquatic environment.     

山东省部分水岸带土壤重金属含量及污染评价

为了解山东省水岸带土壤重金属的含量特征和污染状况,于2010年9月—10月采集了39个水岸带土壤样品,分析了土壤中Cr、Co、Ni、Cu、Zn、Cd、Pb和Hg的含量以及土壤的pH值、粒度和有机质,采用单因子指数法、综合指数法和潜在生态危害指数法对水岸带土壤重金属污染进行了评价,并利用相关分析和聚类分析对其来源进行了初步的解析。结果表明：水岸带土壤的pH值为5.67—8.66,主要呈碱性;有机质的平均含量为9.39 g/kg,土壤粒度主要以砂粒和粉粒为主,其平均体积百分比分别为50.33%和38.48%,平均粒径为89.69 μm;Cr、Co、Ni、Cu、Zn、Cd、Pb和Hg的平均含量为53.03 mg/kg、10.33 mg/kg、24.96 mg/kg、18.38 mg/kg、56.13 mg/kg、0.142 mg/kg、22.48 mg/kg和0.020 mg/kg。各水岸带土壤重金属的含量均符合《土壤环境质量标准》（GB15618-1995）二级标准。以山东省土壤元素背景值为评价标准,水岸带土壤重金属总体表现为轻度污染和轻微生态风险,其中Cd和Hg是主要的污染因子,其对潜在生态危害指数的平均贡献率分别为46.8% 和33.6%。洙赵新河、廖河、门楼水库和东平湖水岸带土壤重金属污染及潜在生态危害明显高于其他水源地。源解析的结果表明：水岸带土壤重金属的含量受自然源和人为源的双重影响,人为源主要包括地表径流、工业废气、垃圾和交通运输等。     

Sediment Heavy Metal Contents,Ostracod Toxicity and Risk Assessment in Tropical Freshwater Lakes,Tamil Nadu,India

ABSTRACT

Coimbatore is one of the industrial cities in Tamil Nadu, India, which has been experiencing rapid urbanization and population growth. Coimbatore is also known for its unique freshwater lakes environment and serves as a rich ecosystem. However, the assessment of heavy metal levels in aquatic environments is limited. This study was aimed to investigate physicochemical parameters, heavy metals level and sources, and ecotoxicity in sediments collected from five different lakes in Coimbatore. The concentrations of heavy metals (Cr, Cu, Zn, As, Cd, and Pb) in sediments were determined by Inductive Coupled Plasma-Mass Spectroscopy (ICP-MS). Hg level was measured using Advanced Mercury Analyzer (AMA). The determined heavy metal concentrations in sediments varied significantly according to the lake location and consistent with local human linked anthropogenic activities. The metal concentrations in urban lakes were exceeding both the Sediment Quality Guidelines (SQGs) and the probable effect levels” (PELs) mostly; e.g., in sediments from the Lake Ukkadam, the values of 5.08 and 203.32 mg kg-1 dry weight were observed for Hg and Cu, respectively. The ecotoxicity test with ostracods exposed to the sediment samples revealed that mortality ranged between 6 and 23% for countryside lakes and 28 and 88% for the lakes within urban Zone. We used Spearman rank-order correlation and Principal components analysis (PCA) to assess the sources of pollutants and if they related to anthropogenic pressure and eutrophication of lakes. The main sources of heavy metals from studied lakes differed significantly. Urban and industrial effluents were dominant sources in urban lakes. Agricultural runoff, domestic wastes, and natural weathering were responsible for the metal sources in country lakes. This study provides baseline information on the heavy metal pollution status of sediments in the freshwater lakes in Coimbatore, which will be useful for pollution control measures to prevent possible metal sources on these lakes and impose appropriate management practices and continuous monitoring by relevant authorities.