Major and trace elements in Sphagnum moss from four southern German bogs,and comparison with available moss monitoring data

In this paper, we present concentrations of an array of major and trace elements (Ag, Al, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Rb, Sb, Sc, Sr, Th, Tl, U, V, Zn) in living Sphagnum mosses from four southern German bogs and compare them with moss monitoring data of the respective regions. To do this, Sphagnum mosses were collected in Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and, one year later, the annual moss production was harvested. Up to 12 samples (40 cm × 40 cm) were collected per site, and 6–10 sites investigated per bog. The concentrations of these elements were then determined in acid digests using sector field ICP-MS. Variations within a given sampling site were in the range of 2 to 3-fold for all major and trace element concentrations except for Mn (12-fold) and Tl (38-fold). For most of the elements, concentrations between bogs of a given region were significantly different and atmospheric deposition of particles seems to be considerably affected by local circumstances such as tree canopy interception and microtopography. Comparing trace element concentrations measured in Sphagnum mosses for 2007 with published moss monitoring data for 2005 resulted in a very good agreement for most elements. Clearly, Sphagnum mosses from bogs are useful biomonitors for estimating atmospheric contamination by metals. This supports the use of Sphagnum in atmospheric deposition monitoring especially in cases where Sphagnum is abundant (e.g., boreal forests). In regions with neither bogs nor forests, living Sphagnum moss bags could be used to the same effect.     

Traffic exposure increases natural 15N and heavy metal concentrations in mosses

Mosses have been used as biomonitors of atmospheric pollution for some years, but few studies have been carried out on the effect of NO_x emissions from traffic on moss tissue N. Eight species of moss (102 samples) growing on walls or roofs next to roads exposed to different traffic densities were collected from urban and rural sites in the UK. The shoots were sampled for total N, their stable isotope ¹⁵N/¹⁴N content (δ¹⁵N) and heavy metal content (Pb, Zn). There was a lack of correlation between tissue total N and traffic exposure, but a very good correlation between traffic exposure and tissue δ¹⁵N. Plants collected near motorways or busy urban roads had δ¹⁵N values ranging between +6 and −1‰, while in rural areas with hardly any traffic these ranged from −2 to −12‰. In a separate survey of mosses, the average δ¹⁵N of shoots from busy roadsides in London was +3.66‰, whereas from samples collected from farm buildings near poultry or cattle pens it was −7.8‰. This indicates that the two main atmospheric N sources, NO_x and NH_x, have different δ¹⁵N signatures, the former tending to be positive and the latter negative. Tissue concentrations of both Pb and Zn show a strong positive correlation with traffic exposure, with Zn in particular being greater than Pb. The results are discussed with regard to the use of moss tissue Zn as a means for monitoring or mapping pollution from vehicles, and of δ¹⁵N as an aid to distinguish between urban (NO_x) and rural (NH_x) forms of N pollution.     

藓袋法对深圳市痕量大气重金属污染物的监测

通过在深圳市盐田、罗湖、福田、南山4个行政区17个不同地点布放藓袋,并对其所吸附的 V、Cr、Mn、Co、Ni、Cu、Zn、As、Cd、Pb 等10种重金属元素的含量进行检测和比较研究,发现4个行政区在不同程度上都受到了污染,其中南山区的污染较轻,罗湖区、福田区与盐田区较为严重。污染程度可能与水陆交通和工业状况、人口密度以及特殊的地理位置有关。对深圳市17个监测点的大气重金属富集含量进行聚类分析发现,污染较为严重的地区均为工业区和交通密集区,污染相对较轻的监测点都离工业及交通污染源相对较远。     

Pollen abortion rates, nitrogen dioxide by passive diffusive tubes and bioaccumulation in tree barks are effective in the characterization of air pollution

This study aims to evaluate the feasibility of using simple techniques - pollen abortion rates, passive diffusive tubes (NO₂) and trace element accumulation in tree barks - when determining the area of influence of pollution emissions produced in a traffic corridor. Measurements were performed at 0, 60 and 120 meters from a major road with high vehicular traffic, taking advantage of a sharp gradient that exists between the road and a cemetery. NO₂ values and trace elements measured at 0 meters were significantly higher than those measured at more distant points. Al, S, Cl, V, Fe, Cu, and Zn exhibited a higher concentration in tree barks at the vicinity of the traffic corridor. The same pattern was observed for the pollen abortion rates measured at the three different sites. Our data suggests that simple techniques may be applied either to validate dispersion land-based models in an urban settings or, alternatively, to provide better spatial resolution to air pollution exposure when high-resolution pollution monitoring data are not available.     

基于多源数据的福州市中心城区人居环境质量评价

城市内部居住环境的客观性评价有助于发现城市发展中暴露出的问题,有针对性地进行调整进而改善城市环境。以福州市中心城区为研究区,居住区为研究单元,利用气象监测数据、遥感影像数据、地图兴趣点数据、国土规划数据等多源数据,从环境健康舒适性、交通便捷性、城市安全性和生活方便性4方面构建城市人居环境监测体系,并使用优劣解距离法进行人居环境质量综合评价。结果表明: 福州市中心城区人居环境水平差异性较大,整体上呈现出中心区域高、边缘地区低的特点。城区中部人居环境指数较高,东部和南部区域较低,西部和北部区域人居环境高值与低值混杂分布。各指标层中,交通便捷性和生活方便性的高-高集聚以及低-低集聚特征与人居环境高低值聚类分布较为一致,便捷的交通以及完备的服务设施对人居环境评价的影响较大;环境健康舒适性呈现城市内部低、边缘高的特点,而城市安全性呈现内部高、边缘低的特点。     

Do moss bags containing devitalized Sphagnum denticulatum reflect heavy metal concentrations in bulk deposition?

The trace elements contained in atmospheric deposition have long been of environmental and human health concern. The concentrations of trace elements in bulk deposition are usually monitored using traditional methods, which are often complemented by use of the simpler and less expensive moss bag technique. However, some theoretical aspects of the latter technique are still not well understood, such as the relationship between the levels of trace elements accumulated in moss and the concentrations of these in the atmosphere. In the present study, the correlation between the concentrations of trace elements (i.e., Cd, Cu, Hg, Pb and Zn) in devitalized moss bags (Sphagnum denticulatum) and bulk deposition was studied during 12 exposure periods at 21 sampling sites (SS) affected by different degrees of contamination. Most of the significant correlations involved Cd and to a lesser extent Cu and Zn; however, no significant correlations were found for Pb and Hg. The environmental conditions and particularly the abundance of precipitation are the main causes of the absence of correlations in some cases, presumably because of the loss of elements via washing. Thus, although the moss bag technique is a very useful and economical environmental tool, the limits of the method must always be borne in mind.     

Do cities export biodiversity? Traffic as dispersal vector across urban–rural gradients

Urban areas are among the land use types with the highes richness in plant species. A main feature of urban floras is the high proportion of non-native species with often divergent distribution patterns along urban–rural gradients. Urban impacts on plant species richness are usually associated with increasing human activity along rural-to-urban gradients. As an important stimulus of urban plant diversity, human-mediated seed dispersal may drive the process of increasing the similarity between urban and rural floras by moving species across urban–rural gradients. We used long motorway tunnels as sampling sites for propagules that are released by vehicles to test for the impact of traffic on seed dispersal along an urban–rural gradient. Opposite lanes of the tunnels are separated by solid walls, allowing us to differentiate seed deposition associated with traffic into vs. out of the city. Both the magnitude of seed deposition and the species richness in seed samples from two motorway tunnels were higher in lanes leading out of the city, indicating an 'export' of urban biodiversity by traffic. As proportions of seeds of non-native species were also higher in the outbound lanes, traffic may foster invasion processes starting from cities to the surrounding landscapes. Indicator species analysis revealed that only a few species were confined to samples from lanes leading into the city, while mostly species of urban habitats were significantly associated with samples from the outbound lanes. The findings demonstrate that dispersal by traffic reflects different seed sources that are associated with different traffic directions, and traffic may thus exchange propagules along the urban–rural gradient.     

Local vehicles add nitrogen to moss biomonitors in a low-traffic protected wilderness area as revealed by a long-term isotope study

Public use of protected areas is typically encouraged, but visitors arriving by vehicles may alter the natural areas they seek. Vehicle emissions add nitrogen oxides (NO_x) and ammonia (NH₃) to the air, which can increase the amount of plant-available (reactive) nitrogen, a limiting nutrient. Changes in ecosystem processes as a result of increases in nitrogen availability are at odds with the goals of many protected wilderness areas that are typically accessed by vehicles. In this multi-year study (2003–2019), we tested whether emissions from local vehicles entered the forest ecosystem adjacent to a highway in a protected wilderness valley near a mid-sized city (Calgary, Alberta, Canada). We examined the concentration of NO₂ in the air and the abundance of combustion-derived nitrogen isotopes (δ¹⁵N) in naturally-occurring forest moss (Hylocomium splendens and Pleurozium schreberi) within 20 m of the highway as a function of traffic levels that varied independently at two scales: along the highway and among years. Within the valley, we observed a gradient in the number of vehicles that was greatest where vehicles enter the valley, with a corresponding pattern for NO₂ concentrations in air. Traffic volume also varied among years, with the highest year having almost twice as many vehicles in the summer as the lowest year. δ¹⁵N values in forest moss displayed similar patterns as traffic both within and among years, signalling that nitrogen from vehicle emissions entered the local ecosystem corresponding to local traffic levels. Because vehicle emissions enter natural ecosystems that are intended to be conserved, vehicle use must be considered in the management of protected natural areas.     

Cadmium contamination in various environmental materials in an industrial area,Hangzhou, China

Abstract

Due to the location of manufacturing in north Hangzhou, many residential areas are close to trunk roads and factory areas. This potentially exposes citizens to pollution sources such as industrial emissions and vehicle exhaust. Because pollution by cadmium (Cd) is of great concern, an extensive survey was conducted in north Hangzhou city to study the current condition of Cd contamination and any resulting hazard. Environmental materials including water, bottom mud, urban green-land soil, street dust and moss were collected. Cd concentration and chemical partitioning in the samples were determined. The results indicate that all the media in north Hangzhou have elevated Cd concentrations, the Cd conten trend being: factory area >traffic area > residential area. The chemical partitioning results show that Cc in topsoil and street dust presents are mobile (9–61% Cd are bound in acetic acid extractable phase) which suggests a high ecological hazard potential. Environmental bioindicator moss samples were found to be loaded with Cd revealing high bioavailability of Cd in various media in north Hangzhou This confirms the possibility of Cd being a potential biohazard in this location.     

Tardigrade Distribution in a Medium-sized City of Central Argentina

The distribution and abundance of tardigrades in the city of General Pico (Argentina) are analyzed from samples collected during autumn and spring 2001. Sample sites included paved urban locations with different traffic intensities, non-paved periurban places, and places with peculiar conditions such as the city industrial area and the bus station. Trees of the same species were selected in each area and from each of them nine subsamples of lichens and/or moss, 11 mm in diameter, were taken with steel corers. The diversity, density and relative abundance of tardigrades was recorded and analyzed. Sampling sites were ordinated and classified with PCA and clustering. The number total of species collected in the research was 5. The maximum number of species per site and per tree was 4. The species recorded were: Echiniscus rufoviridis, Milnesium cf. tardigradum, Ramazzottius oberhaeuseri, Macrobiotus areolatus and an undescribed species of the genus Macrobiotus. The average density was approximately 10 specimens per cm² and the maximum values reach over 50 specimens per cm². R. oberhaeuseri and M. cf. tardigradum were the most frequent species. R. oberhaeuseri dominates in periurban areas with high suspension dust and very exposed to the sun. M. cf. tardigradum dominates on paved streets with intense vehicle traffic. Results supported the hypothesis of the relationship between air quality and tardigrade diversity.     

Spatial patterns,hotspot, and risk assessment of heavy metals in different land uses of urban soils (case study: Malayer city)

A study on identification of hotspots, spatial patterns, and risk evaluation of heavy metals in urban soils of Malayer city (Iran) was carried out. Fifty-nine composite surface soil samples were collected from six different land uses (urban parks, streets, and squares, boulevards, residential and agricultural areas) in Malayer city, and the total heavy metals were measured by atomic absorption spectroscopy. Average concentrations of Cd, Pb, Cu, and Zn, As, Cd, and Pb were 0.66, 15.51, 12.25, and 96.8 mg/kg, respectively. Among the six land uses, heavy metal contamination was heavier for street, while low contamination could be found for residential and urban parks. The spatial distribution of Pb in surface soil was similar to those of Cd, and Cu was similar to those of Zn with decreasing values from the central areas to the suburb. Also, there were several hotspots for studied heavy metals that Cd and Pb were mainly occurred in locations of heavy traffic in the city center and Cu and Zn in the west and northwestern in the city. The calculated result of risk evaluation showed that much of the city suffered from moderate to severe pollution by four of these heavy metals.     

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.     

Metals in Tortula muralis from sandstone buildings in an urban agglomeration

Acrocarpous mosses present on stonewalls in urban areas may be used for monitoring purposes. Therefore for this investigation we selected Tortula muralis expecting that this species with an ability to colonise buildings in polluted agglomerations where other species have vanished may provide important information to monitor environmental quality. Concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in T. muralis, in dust deposited on sandstone surfaces, and in the sandstones on which the moss grew were measured. T. muralis appeared to be a good bioindicator of airborne pollution which accumulated especially extremely high Cu, Fe and Zn concentrations reaching values much higher than harmful for plants. There was no relation between metal concentrations in underlying sandstones and T. ruralis. There was a relation between metal concentrations in dust and T. muralis. Cd, Co, Cr, Mn and V concentrations in T. muralis were higher than in dust. The Self-Organizing Feature Map identifying groups of sampling sites with similar concentrations of metals in mosses was able to classify the pollution level by distinguishing groups of highly, medium and less polluted sites. Once trained, SOFM can be applied in ecological investigations and could form a future basis for recognizing e.g. the type of pollution in urban environments by analysing the concentrations of elements in T. muralis.     

Leaf carbon isotope ratio and water use efficiency of urban roadside trees in summer in Kyoto city

The effect of summer climate on leaf carbon isotope composition (δ¹³C) of the major roadside tree species Prunus × yedoensis (P. yedoensis) was investigated in Kyoto city, Japan, to explore the implications for alterations in urban environments. Temperature and the vapor pressure deficit were higher at sites of higher traffic volumes, possibly affected by a heat island effect. The leaf δ¹³C of P. yedoensis trees was affected strongly by leaf carbon isotope discrimination (Δ), with much less effect of δ¹³C on atmospheric CO₂. Leaf Δ values in the summer were smaller at sites of higher traffic volumes with high atmospheric temperatures, suggesting a higher long-term water use efficiency (WUE) at these sites. Gas exchange measurements of P. yedoensis leaves indeed suggested a higher intrinsic WUE at sites of higher traffic volumes with high atmospheric temperatures. These results suggest that leaf Δ is related to the response of WUE to summer climates, and that leaf δ¹³C in urban areas is a useful tracer for understanding the influences of urban environments on plant photosynthetic processes.     

不同土地利用方式对城市土壤质量的影响

通过对兰州市西固区种土地利用类型(工业园区、道路两侧、农业、居民区和公园)320个土壤样品的测试,研究了不同土地利用方式对城市土壤理化性状和Pb、Zn、Cd、Cu、Hg元素积累的影响.在种类型土壤中,工业园区土壤的pH值最低而电导率最高,道路两侧土壤有机碳含量显著高于居民区、公园和农业土壤;Pb、Zn、Cu、Cd和Hg的含量在种类型土壤中存在显著差异,并明显高于兰州市土壤背景值;计算得到的工业园区、道路两侧、农业、居民区和公园土壤的内梅罗综合污染指数分别为4.9、3.7、4.0、2.4和2.2.结果表明,不同土地利用方式对城市土壤质量的影响不同,工业活动的影响最大,交通污染次之,再依次为农业活动及居民生活.     

Geochemical Assessment of Two Excavated Mass Graves in Rwanda: A Pilot Study

Necrosols are a unique category of anthropogenic soils that are associated with excavated cemeteries or graveyards. In spite of the growing number of cemeteries and burial sites found across urban and rural areas globally, scientific information regarding the contamination potential of this category of soils is relatively scarce and not properly understood. The purpose of this study is to fill this gap by assessing the contamination significance of trace metal contents in the necrosols associated with two excavated mass graves in Rwanda. For this preliminary geochemical investigation, cemetery soil samples were collected from two excavated mass graves in the Murambi memorial site, Rwanda, and analyzed for trace and major element concentrations. The enrichment factor (EF), chemical index of alteration (CIA), and contamination status of necrosol samples was determined in comparison with the offsite area. The results revealed that the average EF values for both onsite and offsite samples were generally within the class of natural background with only six onsite samples having higher EF values than the offsite or background area. Possible reasons for the progressive depletion of the selected trace element onsite are the relatively low anthropogenic activities and higher weathering intensity of the necrosols in comparison with the background area over time. Even though the mean onsite CIA values for the necrosols were slightly higher than the background area, the index further confirmed that both the necrosols and offsite samples were significantly altered to kaolinic degree. From the resulting pollution index values (PI _Nemerow), it can be inferred that the Murambi necrosols were within the range of 0.84 and 1.82, corresponding to the precaution and slightly polluted domain. The current contamination status of the necrosols is likely to have been caused as a result of the anthropogenic input of Cr and Pb onsite relative to the offsite area.     

‘Land-use mixité’: Evaluating urban hierarchy and the urban-to-rural gradient with an evenness-based approach

This study illustrates an original approach to assess city hierarchy in metropolitan regions and to investigate urban gradients using local-scale socioeconomic data. By linking land-use to the diversification in the level of land imperviousness, we consider fragmentation and diversity in the use of land to distinguish urban from rural areas. We applied an entropy function to a map of land imperviousness in Athens' metropolitan region, Greece, with the aim to classify municipalities into urban and rural types based on Shannon diversity and Pielou evenness indexes. Urban areas are hypothesized to have higher diversification in the degree of imperviousness than rural areas. Principal Component Analysis and Canonical Correlation Analysis were used to verify the spatial coherency between land imperviousness and the distribution of urban land-use. Land imperviousness Pielou index increased linearly with both diversity in the use of land and ancillary variables assessing the urban gradient (population density and distance from the inner city). Our study identifies urban and rural municipalities respectively as the most and the less diversified in terms of land-use and imperviousness intensity, with suburban areas ranking in-between. Pielou evenness index applied to land imperviousness maps and the notion of land-use diversification are promising tools to monitoring city hierarchy along urban gradients.     

上海市地面藓类植物的分布格局分析

在上海市选取20个公园和2个化工厂设立22个样点,对地面藓类植物进行野外样方调查、标本鉴定和数据统计．基于75种记录的藓类植物及其盖度数据,应用双向指示种分析法(TWINSPAN)和除趋势对应分析(DCA)分析其分布格局．结果表明,上海市地面藓类植物可聚类为3个样点组,样点组1为市中心2个公园和2个化工厂,共有藓类23种,总盖度最小(21．29％);样点组2为部分市中心公园和外围公园,共有藓类44种,总盖度37．94％;样点组3主要为外围公园和市郊公园,共有藓类49种,总盖度为49．66％．结果反映了藓类植物分布与不同生境,环境污染及人为干扰有一定相关性．     

Deciduous tree leaves in trace elements biomonitoring: A contribution to methodology

Air quality biomonitoring using plant leaves has been widely applied to assess the effects of atmospheric pollution. Although practiced for many years, it has not given completely satisfactory data, due to different and even opposing results. This study comprises an investigation on the content of some trace elements (Al, As, Ba, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Pb) in leaves of four tree species common for the urban area of Belgrade (Serbia). The assay took place in July 2009 when the selected trees (Acer platanoides, Aesculus hippocastanum, Betula pendula, Tilia cordata) were in the maximum of physiological activity during the vegetation season. Among the investigated species, leaves of A. platanoides contained the highest concentrations of the measured elements. The assumption that a large green area in the Belgrade city periphery would be a suitable control site appeared to be disputable due to the substantial load of the elements obtained in the leaves. It was shown that even a short rinse with bidistilled water (3–5 s), applied twice to the leaves prior to chemical analysis, led to a significant decrease of some element concentrations (most pronounced for Al, Fe and Pb in all species, but also evident for Cu, Cr, Co and Zn for some of them). However, by washing leaves, the representativeness of leaf samples per studied site could be improved due to removal of some superficial loosely adhered impurities and so diminished large variability of element concentrations among leaf subsamples providing more representative information on the element content in leaves per site, and the area, respectively.