Heavy metal accumulation in aquatic animals around the gold mine area of Loei province,Thailand

This research was conducted to assess the water quality and the contamination of heavy metals in water, sediment, fish, and frogs, as well as bioaccumulation factors (BAFs) in fish and frogs around the gold mine area. The water samples were analyzed for water quality (temperature, pH, and dissolved oxygen). The samples were analyzed for heavy metals by inductively coupled plasma optical emission spectrometry. The water quality was within the standard. The concentrations of heavy metals, including As, Cr, Cd, Pb, Ni, Zn, Fe, Mn, and Cu, in water and sediment samples were measured. Three species of fish were collected: Rasbora tornieri, Brachydanio albolineata, and Systomus rubripinnis. The mean heavy metal concentrations of fish were as follows: Fe>Zn>Mn>Cr>Ni>Cu>As>Pb>Cd. The As, Cr, and Pb concentrations in all the fish species exceeded the standard levels. Five species of frogs were collected: Kaloula pulchra, Microhyla heymonsi, Fejervarya limnocharis, Hoplobatrachus rugulosus, and Microhyla pulchra. The mean heavy metal concentrations of frog were as follows: Fe>Cu>Mn>Zn>Cr>Ni>Pb>Cd>As. The Cr, Cd, and Cu concentrations exceeded the standard levels. The BAFs in fish were in order of Cr>Zn>Ni>Cu>Pb>Fe>Cd>As. The BAFs in frogs were Cr>Zn>Ni>Cu>Fe>Pb>Cd>As. The accumulation of heavy metals was higher in the sediment than in the water. Many aquatic organisms take up heavy metals directly from the environment around the gold mine.     

Seasonal accumulation of metals by red alga Gracilaria verrucosa (Huds.) Papens. from Thermaikos Gulf, Greece

Concentrations of Fe, Pb, Cu, Zn and Cd were determined during one season in the red alga Gracilaria verrucosa, sediment and seawater from the Thermaikos Gulf, Greece. This region has been subject to change due to increases in industrial and domestic activities. The relative abundance of metals in G. verrucosa and seawater decreased in the order: Fe>Zn>Pb>Cu>Cd and in the sediment: Pb>Fe>Zn>Cu>Cd. Cadmium concentration in the alga correlated positively with that in seawater. There was positive correlation between Fe concentrations in the alga and those of the Zn and Cu. The concentrations of metals in the alga showed no significant differences between the stations. Lead, Zn and Cu concentrations in the alga were slightly higher at Biamyl, whereas Cd was higher at Perea and Fe at Nea Krini. Seasonal variation of metal concentrations in the alga was significant for Cd and Fe. Copper and Fe increased from winter to summer, whereas Cd was the opposite. Zinc concentrations were minimum and Pb concentrations were maximum during spring. These variations are discussed in relation to tissue age, life cycle, ambient concentrations of metals and other environmental conditions. Cd and Pb concentrations inG. verrucosa in the Thermaikos Gulf were higher and those of Cu and Zn were lower than in other species of the genus. This revised version was published online in August 2006 with corrections to the Cover Date.     

Source identification and risk assessment of heavy metals in road dust of steel industrial city (Anshan), Liaoning,Northeast China

Abstract

The purpose of the study was to acquire the source and evaluate the risk posed by heavy metals in road dust of steel industrial city (Anshan), Liaoning, Northeast China. Potential ecological risk index (RI), pollution index (PI) and geo-accumulation index (Igeo) were applied to evaluate the heavy metal pollution level, and the carcinogenic risk (RI) and hazard index (HI) were calculated to estimate the human health risk. The geographic information system maps clearly reveal the hot spots of heavy metal spatial distribution. Principle component analysis (PCA) and cluster analysis (CA) classified heavy metals into three groups. The metal Zn and Pb originate from the traffic emission, while Cd, Cr, Fe, Mn, Ni and Sb primarily come from industrial activities. These two pathways were the major source of heavy metals pollution by positive matrix factorization (PMF). The Igeo and PI values of heavy metals were decreased in the following order: Cd?>?Sb?>?Zn?>?Fe?>?Pb?>?Cu?>?Cr?>?Sn?>?Mn?>?Ni. The RI index showed the heavy metals were moderate to very high potential ecological risk. The HI values for children and adults presented a decreasing order of Cr?>?Pb?>?Ni?>?Cu?>?Cd?>?Zn. The HI also predicted a possibility of non-carcinogenic risk for children living in urban areas in comparison with adults.     

Geochemical distribution of heavy metals in sediments from sewage fed fish ponds from Kolkata Wetlands,India

Abstract

Kolkata wetlands are the largest sewage fed wetlands in the world. They have been used for aquaculture since 1960. Geochemical distribution of heavy metals (Cr, Cu, Mn, Fe, Zn, Pb, Ni and Al) has been studied in surface sediments using single and sequential extractions techniques. The metal concentrations in sediments were in the following order: Fe>Al> Mn>Zn>Cu> Pb>Cr> Ni, and the average concentrations were 29 μg g^?1, 54 μg g^?1, 328 μg g^?1, 32747 μg g^?1, 169 μg g^?1, 38 μg g^?1, 25 μg g^?1 and 23371 μg g^?1 dry weights for Cr, Cu, Mn, Fe, Zn, Pb, Ni and Al, respectively. Water-soluble percentages of the trace elements are quite low (<0.01–3.75%) but in the presence of chelating agents in the sediments increase the bioavailability of trace elements (2–58%). About 40% of trace elements are in the stable form as a residual fraction of the sediment and more than 50% (nonresidual fraction) metal contamination of the Kolkata wetland sediments were from anthropogenic inputs. The contamination risks of Cr, Mn, Zn, Pb, and Ni are high as their potential availabilities are 70.96%, 58.01%, 63.13%, 55.62%, and 52.15% respectively. The mean concentration of most of the heavy metals in sediments does not exceed the recommended reference values. Zinc and lead concentrations were greater than background level and Interim Sediment Quality Guidelines but lower than Probable Effect Level. Therefore a regular program for monitoring the distribution of heavy metals in water, sediments and biota should be imposed on sewage fed fish ponds of the Kolkata wetland ecosystem.     

Relationships Between Metal Concentrations in Human Hair and in Soil,Road Dust,and Rice

The relationships between metal contents in soil, road dust, and rice, and in human hair from a rural area of China were observed for Cr, Cu, Mn, Ni, Pb, and Zn. The results showed that the mean concentrations of Mn in human hair were higher than the highest reference value. The concentrations of Cr, Cu, Ni, and Zn in soil and road dust were usually higher than their background values. The enrichment factors indicated that the determined metals in soil and road dust were usually derived from natural sources. Chromium, Pb, and Zn in soils and road dusts from several sites were slightly influenced by anthropogenic sources. The regression analyses showed that positive relationships usually exist between the concentrations of the determined metals in rice and in human hair as well as in soil and in human hair. However, relationships between metal concentrations in road dust and in human hair were less obvious. The study demonstrated that human hair was an applicable biomonitor of metal concentrations in rice, soil, and road dust from a rural area in China. Metal concentrations in local human hair could be used to predict contamination levels of metals in rice and soil.     

Concentration and ecological risk of heavy metal in street dusts of Eslamshahr,Iran

This study was done to evaluate heavy metal concentrations in street dust samples, to compare measured concentrations in samples to background concentrations in order to make evaluations for pollution indices, and to describe the quality of street dust in the studied area in relation to pollution. A total of 30 cumulative samples were collected from the streets of Eslamshahr City. Concentrations of heavy metals were determined using an Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Results determined mean concentrations (mg/kg) of the heavy metals Cd, Cr, Cu, Ni, Pb, and Zn, in collected samples of street dust as 0.34, 35.1, 239, 42.4, 71.3, and 573, respectively. I_geo values for Cd and Cr, Cu, Ni, Pb, and Zn showed level of moderately polluted, unpolluted, moderately to strongly polluted, unpolluted, moderately polluted and moderately to strongly polluted, respectively. The pattern of total metal concentrations in the studied area was ranked as follows: Zn and Cu>Pb>Cd>Ni>Cr. The highest values for the monomial potential ecological risk (E_r) were observed for Cd (114). The mean level of RI for the studied soil samples was 192 (91.3–244), which is classed as presenting a strong potential ecological risk.     

Trace metal fractionation in water and sediments of an urban river stretch

Abstract

In this study, the fractionation and ecotoxic potential of Cr, Ni, Cu and Pb in water and sediments of the river Yamuna (Delhi stretch) is presented. The river water is used for various purposes such as irrigation, industrial, domestic and drinking. The investigations suggest that the availability of metals in water follows the sequence Ni>Cr>Pb>Cu whereas a different pattern (Pb>Cu>Ni>Cr) is observed in sediments. Statistically significant spatial variations are indicated by two-way ANOVA in different geochemical forms of the metals and physicochemical parameters of water and sediments of the river Yamuna. Principal component analysis (PCA) suggests a similar source for all four metals probably from the sewage from municipal drains. PCA also indicates some independent sources of Cu and Pb. The hot spots were identified using hierarchical cluster analysis considering bioavailable forms of the metals in water and sediments as objects and the sampling sites as variables. Risk assessment code analysis indicates that metals generally pose medium to high risk at different sites. However, at a few locations either Ni or Pb cross the level of very high ecological risk.     

Distribution of heavy metals and their chemical speciation in sediments from the Abelardo L. Rodríguez Dam,Sonora, México

Abstract

The purpose of this study was to investigate the distribution of total and bioavailable metals (Cd, Cu, Cr, Fe, Mn, Pb and Zn) in sediments of the Abelardo L. Rodríguez (ALR) dam located in the eastern part of the city of Hermosillo, Sonora, Mexico. Seventy two sediment samples were collected in 2009 during four sampling campaigns in February (spring), May (summer), September (end of summer) and December (winter) in five different areas within the dam surface (Zones I, II, III, IV and V), including the Gate Station. Determination of heavy metals was carried out by flame atomic absorption spectrophotometry (FAAS). The results indicate high levels of total heavy metals in the following order: Fe>Mn>Zn>Pb>Cu>Cr>Cd. This is indicative of the impact of human activities located in areas surrounding the reservoir, specifically urban and industrial. The distribution and state of accumulation of trace metals in the sediment is largely dominated by the residual and Fe/Mn oxides geochemical phases. Fraction I (exchangeable) also presented high concentrations of metals (Cu, Fe, Mn and Zn). From enrichment factor analysis, the study area is prevalently enriched in Cd, Cu and Pb in Zones I, II, III, IV and Gate Station. This indicates that the sediments are impacted by anthropogenic activities such as downloads, domestic and industrial wastewater. Geoaccumulation index (Igeo) indicates that Zones I, II, III, IV and V (including Gate Station) do not show contamination by Cr, Fe, Mn and Zn. However, there is a moderate to heavy contamination by Cd, Cu and Pb (Igeo: 2–4) in all areas of study. The comparison between the results obtained with the sediment quality criteria (LEL and SEL), indicate that Zones I, II, III, IV, V and Gate Station, are contaminated with Cd, Cu and Pb, and severely contaminated by Fe.

The elevated levels of heavy metals detected in the sediment of the ALR Dam require special attention, since in the exchangeable fraction, the metals are specifically adsorbed on the sediment and can be released when the ionic composition of water changes. However, additional studies are required in this reservoir on the chemistry and toxicology of metals for a full assessment of potential risks posed to biota and man.     

Impact of treated municipal wastewater irrigation on turnip (Brassica rapa)

The effect of treated municipal wastewater on the roots and the leaves of turnip was studied to compare the 50% and 100% wastewater of 34 ml/d Sewage Treatment Plant (STP) with different doses of potassic fertilizers. Turnip (Brassica rapa) was used as a test plant. A pot experiment was conducted, using a factorial randomized block design to investigate the growth and translocation of heavy metals to the leaves and the roots of turnip. The concentration of heavy metal in wastewater used for irrigation was within the limits. However, the concentration in the plant parts showed a significant rise due to continuous use of wastewater. The concentration of heavy metals in leaves and roots was at excessive levels at 40 and 55 days after sowing (DAS), while at 70 DAS, metal concentration was comparatively low. The range of heavy metals in wastewater irrigated plants was Cd = 1–16.3, Ni = 0–136, Fe = 263–1197, Cu = 0–18, Mn = 37–125, and Zn = 42–141 mg/kg. Concentration of heavy metals in plants was found in the order of Fe>Zn>Ni>Mn>Cu>Cd.     

Heavy metal contamination in vegetables grown around peri-urban and urban-industrial clusters in Ghaziabad,India

Heavy metal contamination of agricultural soils resulting from rapid industrialization and urbanization is of great concern because of potential health risk due to dietary intake of contaminated vegetables. The present study aims to evaluate the status of heavy metals contamination of agricultural soils and food crops around an urban-industrial region in India. Transfer factor values of Cu, Cr, Pb, Cd, Zn, and Ni from soil to vegetable was estimated. The mean heavy metal concentrations (mg/kg) in agricultural soils (Cu: 17.8, Cr: 27.3, Pb: 29.8, Cd: 0.43, Zn: 87, Mn: 306.6, Fe: 16984, and Ni: 53.8) were within allowable concentrations for Indian agricultural soil. The concentrations of Pb, Cd, Zn, and Ni in crops/vegetables exceeded the World Health Organization/Food and Agriculture Organization safe limits. Relative orders of transfer of metals from soil to edible parts of the crops/vegetables were Cd > Pb > Ni > Zn > Cu > Cr. The enrichment factors of heavy metals in soil indicated minor to moderately severe enrichment for Pb, Cd, and Ni; minor to moderate enrichment for Zn; no enrichment to minor enrichment for Mn; and no enrichment to moderate enrichment for Cu at different sites. Ecological risk index of soil showed considerable contamination in one of the wastewater irrigated sites.     

Bioconcentration of Trace Metals in the Tissues of Two Leafy Vegetables Widely Consumed in South West Nigeria

The trace metal levels in the tissues of two popular leafy vegetables Amaranthus caudatus and Corchrus olithorus widely consumed in Nigeria were assessed from a cultivated floodplain receiving effluents from diverse factories in Ibadan. Although the leaves are primarily consumed, the stems are usually used as a feed for farm animals while the roots are disposed by burning when dry or by composting. The objective of this work was to evaluate the level of trace elements in the tissues of these vegetables at harvest time when they become available to the human ecosystem for exposure to the accumulated trace metals, especially the leaves which are cooked and eaten as soup. The results of the mean trace metal levels in the analyses show that the leaves of A. caudatus had the highest bioconcentration in the following order Ba>Mn>Zn>Cu>Pb>Cr>Co>Ni>Cd>U>Sb, stems: Ba>Zn>Mn>Cu>Cr>Pb>Ni>Co>Cd>U>Sb, and roots: Mn>Ba>Zn>Cu>Cr>Pb>Ni>Co>U>Cd>Sb. In C. olithorus, the order was Mn>Ba>Zn>Cu>Pb>Cr>Co>Ni>Cd>Sb>U in the leaves, Mn>Zn>Ba>Pb>Cr>Cu>Co>Ni>U>Cd>Sb in the roots, and Mn>Zn>Ba>Cu>Cr>Pb>Co>Ni>Cd>U>Sb in the stems. The final result of the vegetable samples showed that the trace metal concentration was in the range of Cr (0.8–58.7), Mn (35.0–9,495.9), Co (0.3–33.6), Cu (2.3–60.3), Zn (16.0–538.2), Cd (0.000–40.53), Sb (0.000–0.037), Ba (13.0–1,175.6), Pb (0.9–39.7), and U (0.0–2.2). The bioconcentration factors (BF) for the transfer of trace metals from soil to the tissues showed a higher ease of bioaccumulation when compared to previous studies. The element with the highest BF in the study was Ba (6.45) in the leaves while the least was Co (0.09) in the roots of A. caudatus. The level of bioconcentration of trace metals in the leaves in most of the samples exceeds the recommended levels given by the World Health Organization (WHO) and Federal Environmental Protection Agency (FEPA), Nigeria and therefore constitutes a potential public health risk to the populace who consume these vegetables cultivated in effluent-impacted floodplains.     

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。     

Growth and metal accumulation potential of Vigna radiata L. grown under fly-ash amendments

The study was undertaken with the aim of testing the feasibility of growing Vigna radiata on fly-ash dykes or on fly-ash contaminated soil. Experiments were conducted in earthen pots (12″) having various amendments of fly-ash with garden soil, press mud and farm yard manure and harvested after 60 days of growth. Various growth variables were analyzed, viz., root-shoot length, biomass yield, number of branches, photosynthetic area and pigments, protein content, in vivo nitrate reductase activity and nodulation frequency. The metal accumulation potential (Fe, Zn, Cu, Cr, Cd) in roots and shoot tissues of plants was determined in various fly-ash amendments and seeds were also examined for their metal content so that they can be utilized for growing in fly-ash-contaminated areas. Our results show that the plants grown in 100% fly-ash accumulated significant amounts of metals due to which general vigor and development of plant are affected. V. radiata grown on ameliorated fly-ash showed tolerant characteristics. Plants accumulated metal in the order Fe > Cu > Zn > Cr > Cd. However, their concentration was more in shoot than root tissue except in the case of Fe, which was found to have accumulated more in root tissues. Press mud (25%) amended with fly-ash was found to be the best ameliorant to support plant growth. It may be concluded from the present study that V. radiata was an ideal crop for growing in fly-ash-contaminated areas for the revegetation of fly-ash landfills.     

Determination of contents of the microelements in the blood and the hair of the Han,Uygur and Kazak people

Atomic absorption spectrometry is used to determine the contents of microelements (such as Zn, Cu, Ca, Mg and Fe) in the all-blood and hair of the Han, Uygur, and Kazak people in normal health state. The results show that the above mentioned elements in the hair arranged successively as Ca>Zn>Mg>Fe>Cu and those in the all-blood of the Han people arranged as Fe>Mg>Ca>Zn>Cu; of the Uygur and Kazak people, as Fe>Mg>Ca>Zn>Cu. This paper reports that the content of the microelement Mg in the all-blood and hair of the Uygur and Kazak people is obviously higher than that of the Han people (P<0.05).     

Mobilization of iron and other micronutrient cations from a calcareous soil by plant-borne,microbial, and synthetic metal chelators

Mobilization of Fe, Zn, Cu, and Mn by various chelators from a calcareous soil was measured using a simple dialysis tube/complexing resin system. Root exudates from Fe-deficient barley increased the concentrations of all four metals in solution by, on average, a factor of 20, and the addition of complexing resin as a sink for heavy metal cations forced steady state solution concentrations to be reached sooner. Root exudates mobilized increasing amounts of the various micronutrients in the following order: Cu<Fe<Zn<Mn. Phytosiderophores isolated from root exudates of Fe-deficient barley mobilized similar amounts of Cu and Zn but somewhat more Fe and considerably more Mn than crude exudate. The synthetic chelators EDDHA and DTPA showed low specificity in micronutrient mobilization, but the microbial siderophore Desferal was relatively more specific, preferentially mobilizing Fe and Mn. The data indicates that phytosiderophores are capable of increasing the amount of complexed cations in solution. Despite their lack of specificity, phytosiderophores were just as effective as Desferal increasing the availability of Fe. Thus, phytosiderophores, as plant-borne chelators, are certainly of significance for the Fe nutrition of cereals grown in calcareous soils.     

Sequential extraction of trace metals and particle size distribution studies of Kainji Lake sediment,Nigeria

Abstract

Sequential extraction was carried out to determine the concentrations of some trace metals (Mn, Cu, Fe, Pb and Cd) in the Kainji lake sediments from seven different locations in four fractions: exchangeable, bound to iron and manganese oxide, bound to organic matters and residual. This was to undertaken to assess the environmental fate of these trace metals. The BCR technique, a modified form of the Tessier method of sequential extraction was used.

The proportion of the mean metal concentrations of the bioavailable metals follows the order Fe>Cu>Pb>Mn>Cd. Generally, Fe was most abundant metal in the sediment and about 40% was found in its bioavailable form. Although Cd contributed least to the bioavailable content, a greater percentage (~60%) was found in the bioavailable fraction. This suggests that Cd is highly mobile and, since it is known to be toxic, its concentration in the bioavailable form constitutes an environmental threat.

The contribution of metals bound to organic matter was found to be high and of the same magnitude as those bound to oxides and constitutes about 70% of the non-bioavailable metal contents. The petrological analysis of the sediments revealed that the sediments were predominantly quartz and rock clays with percussion marks and indentations.     

Metal phytoremediation potential of naturally growing plants on fly ash dumpsite of Patratu thermal power station,Jharkhand, India

Three naturally growing plants Ipomoea carnea, Lantana camara, and Solanum surattense were found in fly ash dumpsite of Patratu thermal power station, Jharkhand, India. They were assessed for their metal uptake potential. The fly ash was slightly alkaline with very less nitrogen and organic carbon but enriched with phosphorus and heavy metals. Lantana camara and Ipomoea carnea showed good translocation from root to shoot for most of the metals except Mn and Pb. The order of metal accumulation in stem of both the plants were Fe(205mg/kg)>Mn(65mg/kg)>Cu(22.35mg/kg)>Pb(6.6mg/kg)>Cr(3.05mg/kg)>Ni(1 mg/kg)>Cd(0.5 mg/kg) and Fe(741 mg/kg)>Mn(154.05 mg/kg)>Cu(20.75 mg/kg)>Pb(6.75 mg/kg)>Ni(4.0 mg/kg)>Cr(3.3mg/kg)>Cd(0.05mg/kg), respectively. But Solanum surattense accumulated most of the metals in roots. The order was in the following order, Mn (382.2mg/kg) >Fe (264.1mg/kg) > Cu (25.35mg/kg) >Pb (5.95 mg/kg) > Ni (1.9 mg/kg) > Cr (1.8mg/kg) > Cd (0.55 mg/kg). The order of Bioconcentration factor (BCF) in root and shoot followed almost the same order as, Mn>Fe>Ni>Pb>Cu>Cr≈ Cd in all the three species. ANOVA showed significant variation in metal accumulation by root and stem between the species. Finally, it can be concluded that Solanum surattense can be used as phytostabilizer and other two species as phytoextractor of metal for fly ash dumpsite reclamation.     

Water quality index,Labeo rohita,and Eichhornia crassipes: Suitable bio-indicators of river water pollution

The present study investigated the water quality index (WQI) of the Kshipra river at Dewas, Madhya Pradesh, India, using native fish Labeo rohita, and plant Eichhornia crassipes. The temperature, pH, dissolved oxygen, alkalinity, turbidity, and dissolved solids were found to be within the prescribed limits. However, heavy metals concentration exceeded the limit except for Cu and Zn. Their occurrence in river water was as follows: Ni > Fe > Cd > Cr > Mn > Zn > Cu. Among these heavy metals, Cd was found to be highly bioavailable, whereas Zn was the least bioavailable metal. Based on WQI, the water was found to be unfit for drinking, and the high WQI value was due to the presence of Cr and Cd. In fish tissues (muscle, liver, gut, gills, and kidney), the highest and lowest metal pollution index was found in gills (45.03) and kidneys (12.21), respectively. Bioaccumulation of these metals resulted in significant depletion of energy reserves (protein, glucose, and glycogen) and also altered hematological parameters. Moreover, liver function tests showed hepatic damage in the exposed fish. In-plant, both the bioaccumulation and mobility factor exceeded 1 for all these metals. On the other hand, the translocation factor was found to be beyond 1 for Fe, Ni, and Zn. These high values make this plant fit for phytoextraction of Mn, Fe, Cu, Zn, and Cd and phytostabilization of Cr in water. Moreover, consumption of L. rohita from the Kshipra River does not pose a non-cancer risk as the target hazard quotient was below 1, but it may pose cancer risk because of the presence of Cr in the range of 1.402 × 10^?3 to 1.599 × 10^?3.     

Size fractions of dust and amount of associated metals on leaf surface and inner wax of 15 plant species at Beijing roadside

To provide more insight into the removal ability of urban air dust and associated metals by plant leaves, and thus guide urban green planning to improve air quality, 15 plant species leaves collected from Beijing roadside were analyzed for size fractions of leaf surface dust (SD) and inner wax dust (WD). Seven associated metals Cd, Cr, Cu, Fe, Mn, Pb and Zn were also measured. Metal Accumulation Index (MAI) was calculated for different species leaves at various dust sizes and soluble forms, respectively. Cluster analysis was used for the plant species and correlations between dust and metal concentrations and for inter-metal concentrations were calculated for both surface and inner wax dust. Mean leaf total dust TD (SD?+?WD), SD and WD were measured as 1159, 817 and 342?mg m^?2, respectively, with the highest values observed all in Euonymus japonicus. Most species leaves collected larger ratios of SD than WD except Salix babylonica and Robinia pseudoacacia. While SD was presented at all particle size fractions for all plants, nearly all species leaves collected higher proportions of WD >10?µm. Mean metal levels of leaf TD of all species ranged from high to low as Fe?>?Cr?>?Zn?>?Pb?>?Cu?>?Mn?>?Cd, but with different orders for individual species. Metals were observed in all sizes of SD/WD, although the size distributions were various for certain metals. Intercorrelations of metal concentrations in leaf SD/WD were positively significant except Pb, which may have different emission sources. Species Prunus cerasifera f. atropurpurea, Syringa oblata, Malus micromalu, Koelreuteria paniculata and Robinia pseudoacacia may possess better overall metal collection ability due to their relatively higher MAI values, but species Euonymus japonicus, Malus micromalu, Ligustrum x vicaryi and Koelreuteria paniculata were identified as the best choices in removing air dust based on cluster analysis and suggested to be planted at heavy trafficked road site for air quality improvement.