Soil contamination by metals with high ecological risk in urban and rural areas

Industrial development, intensive agriculture and fast urbanization have caused the metal contents of soils to increase to many times the allowable limits. To assess this impact on urban and rural soils, we quantified the Cd, Cr, Cu, Pb, Ni and Zn contents of 258 soil samples from the Recife metropolitan region (RMR). The objectives of the study were to estimate the probability of ecological risk, to determine the spatial pattern of the metals’ accumulation in the soil and to identify potential sources for the metals using a multivariate geostatistical approach. Mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in soils were 65.2, 17.9, 16.5, 12.8, 6.3 and 1.5 mg kg^?1, respectively. The results demonstrated that the Cd was anthropogenic in origin, the Cr and Ni were lithogenic (natural) in origin and the Cu, Pb and Zn were mixed in origin. Cd contaminated 91% of the samples; the median content of Cd (1.4 mg kg^?1) was three times the quality reference value for soil. The Cd contents of sugarcane fields exceeded the allowable limit (3.0 mg kg^?1) for agricultural areas. The spatial variability of the metals in the RMR showed that metallurgy, cement production, vehicle exhaust and vehicular traffic were the main sources of metals in urban areas, while phosphate-based fertilizers were the main sources in rural areas. More than 80% of the metropolitan region surveyed in the study was at moderate to high ecological risk.     

Assessment of heavy metal contamination levels of street dust in the city of Lublin,E Poland

Heavy metals are constantly emitted into the environment and pose a major threat to human health, particularly in urban areas. The threat is linked to the presence of Cd, Cr, Cu, Ni, Pb, and Zn in street dust, which consists of mineral and organic particles originating from the soil, industrial emitters, motor vehicles, and fuel consumption. The study objective was to determine the level of street dust contamination with trace metals in Lublin and to indicate their potential sources of origin. The analyses were carried out with an energy-dispersive X-ray fluorescence spectrometer. The sampling sites (49) were located within the city streets characterised by varying intensity of motor traffic. The following mean content values and their variation (SD) were determined: Cd: 5.1?±?1.7 mg kg^?1, Cr: 86.4?±?23.3 mg kg^?1, Cu: 81.6?±?69.2 mg kg^?1, Ni: 16.5?±?3.9 mg kg^?1, Pb: 44.1?±?16.4 mg kg^?1, and Zn: 241.1?±?94.6 mg kg^?1. The level of pollution was assessed with several widely used geochemical indices (geoaccumulation index, enrichment factor, pollution index, index of ecological risk, and potential ecological risk index). For most of the indices, the mean (median) values are arranged in the following manner: Zn?>?Cu(or Cd)?>?Pb?>?Ni?>?Cr. In general, street dust in Lublin does not show pollution with Cr, Ni, and Pb. I_geo and EF indices show moderate levels for Cu, Cd, and Zn; their presence in street dust is linked with anthropogenic factors (motor traffic). A significant threat is posed by Cd, and more than half of the samples show considerable pollution with cadmium (median for the index of ecological risk: 151). The spatial pattern of indices and the results of statistical analyses (CA, PCA) indicate three groups of elements: (1) Cr and Ni: natural origin; (2) Pb: mixed origin; and (3) Cd, Cu, and Zn: anthropogenic origin (mainly motor vehicle traffic). Higher content values for metals of anthropogenic origin in street dust indicate that it is a source of pollution of soil and air in the city.     

Enrichment pattern of leachable trace metals in roadside soils of Miri City,Eastern Malaysia

This article presents the results on distribution and enrichment pattern of acid-leachable trace metals (ALTMs) from roadside soil of Miri city, Sarawak, East Malaysia. The city is one of the fastest developing in the Malaysian region with huge petroleum resources. ALTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd along with organic carbon and carbonates (CaCO₃) were analyzed in 37 soil sediments collected from roadside. The enrichment of ALTMs [especially Cu (0.4–13.1 μg g^?1), Zn (9.3–70.7 μg g^?1), Pb (13.8–99.1 μg g^?1)] in the roadside soils indicate that these metals are mainly derived from sources related to traffic exhausts, forest fires and oil refineries. The comparative study and enrichment pattern of elements indicates that Mn, Cu, Zn and Pb are enriched multi-fold than the unpolluted soil and Ni, Pb, Cd in some samples compared to Sediment Quality Guidelines like Lowest Effect Level (LEL) and Effects Range Low (ERL) in the region which is mainly due to the recent industrial developments in the region.     

Rate of deposition and quality of sedimentation dust in Al Ain and Ras Al Khaimah, United Arab Emirates

This study presents data on the mineralogy and the metal content of dust deposited in Al Ain and Ras Al Khaimah, United Arab Emirates. The mineralogical compositions of the dust were determined using X-ray diffraction, and the results revealed that quartz is the dominant mineral, whereas calcite, dolomite, plagioclase, and serpentine were minor minerals. Two sampling sites were chosen from both Al Ain and Ras Al Khaimah. The concentrations of Fe, Zn, Cu, Cr, Pb, Cd, Ni, and Co in the sedimentation dusts samples of these sites were determined using inductively coupled plasma. The levels of most of heavy metal were generally below those determined in the other cities in the Middle East. The air enrichment factors for all the samples were analyzed, and the results indicated that Cd, Zn, Co, and Ni were highly enriched relative to their crustal ratios (to Fe) and correspond to substantial contribution of anthropogenic source of these metals. These metals mainly originate from the traffic emissions and industrial activities with contribution from natural sources. The average rates of deposition in Al Ain and Ras Al Khaimah were 193 and 972 mg m^?2 day^?1, respectively. These rates were higher than those of other regions.     

Trace metal and radionuclide pollution in marine sediments of the Aegean Sea (Izmir Bay and Didim)

To determine radioactivity and trace metal levels, surface sediments were collected from two important areas (?zmir Bay and Didim) in the Aegean Sea region of Turkey, and were analyzed for concentrations of ²¹⁰Po, ²¹⁰Pb and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). The average ²¹⁰Po and ²¹⁰Pb massic activities in sediments varied in the range of 24 ± 5 to 126 ± 6 Bq kg^?1 dry wt. and 18 ± 3 to 59 ± 4 Bq kg^?1 dry wt., respectively. Izmir Bay exhibited the highest polonium activities in sediments, likely due to specific sedimentation processes and other sediment characteristics. The trace metal results showed that the Izmir Bay is facing trace metal pollution. The metal concentrations in sediment samples are low compared to those from the other neighboring marine environments.     

The diagenetic geochemistry and contamination assessment of iron,cadmium, and lead in the sediments from the Shuangtaizi estuary,China

Sediment and pore water samples have been collected from the coastal tidal flat in the Shuangtaizi estuary, China, in order to investigate the geochemical behavior of iron, cadmium, and lead during diagenesis and to assess the degree of contamination. The calculated enrichment factors and geoaccumulation indices for separate elements show that anthropogenic activities have had no significant influence on the distribution of Fe and Pb in the study area, whereas the distribution of Cd has been closely influenced in this way. The high percentage of exchangeable Cd (average of 56.34%) suggests that Cd represents a potential hazard to benthic organisms in the estuary. The calculated diffusive fluxes of metals show that the most mobilized metal is Fe (9.22 mg m^?2 a^?1), followed by Cd (0.54 mg m^?2 a^?1) and Pb (0.42 mg m^?2 a^?1). Low Fe²⁺ contents in surface pore water, alongside high chromium-reducible sulfur contents, and low acid-volatile sulfur, and elemental sulfur contents at 0–25 cm depth in sediments show that Fe²⁺ is formed by the reduction of Fe oxides and is transformed first to a solid phase of iron monosulfides (FeS) and eventually to pyrite (FeS₂). The release of adsorbed Pb due to reductive dissolution of Fe/Mn oxides during early diagenesis could be a source of Pb²⁺ in pore water. From the relatively low total organic carbon contents measured in sediments (0.46–1.28%, with an average of 0.94%) and the vertical variation of Cd²⁺ in pore water, sulfide or Fe/Mn oxides (instead of organic matter) are presumed to exert a significant influence on carrying or releasing Cd by the sediments.     

Accumulation of potentially toxic elements in sediments in Budi Lagoon,Araucania Region,Chile

The concentrations of Cd, Cu, Mn, Ni, Pb, Fe and Zn were determined in superficial sediments extracted from nine zones of Budi Lagoon, located in the Araucanía Region (Chile). The concentrations of these metals were determined by flame atomic absorption spectroscopy and the method was validated using certified reference material (marine sediment). The concentration ranges found for the trace elements were: Pb < 0.5; Cd < 0.2–3.9; Cu 21.8–61.9; Ni 31.2–59.4; Zn 54.5–94.8 mgkg^?1 (dry weight). The elements that registered the highest concentrations were Mn 285.4–989.8 mgkg^?1 and Fe 4.8–10.6 %. The lagoon cluster analysis of the stations was divided into three groups (Temo station with high Cu and low Mn concentrations, Bolleco, Comué, Allipén and Deume 3 stations presented highest Cd concentration, and another group Botapulli, Río Budi, Deume 2 and Deume 1 stations presented low levels of Cd). The textural characteristics of the sediment were determined (gravel, sand and mud) and the results were correlated with the concentrations of the metals in the various study zones. The sediments of Budi Lagoon presented high levels of Fe and Mn, which are of natural origin and exceed the maximum values recorded by many authors. With respect to the recorded concentrations for Cd, Cu, Ni and Zn, are within the ranges published by other authors in similar works. The Pb element was not detected. The results were subjected to statistical analysis to evaluate the correlations between the content of the elements and obtain the site of sediment.     

Metal distributions in seawater,sediment and marine benthic macroalgae from the South Australian coastline

Algal species which are ubiquitous along the coastlines of many countries reflect the environmental conditions of the coastal seawater and may serve as useful biomonitors of anthropogenic pollution. Heavy metal concentrations of ten elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of potential environmental concern were determined in seawater, sediments and twelve species of benthic marine macroalgae from four locations (Glenelg, Port Adelaide, Port Broughton and Port Pirie) along the South Australian coastline. The four sites chosen represented varying degrees of metal contamination, where the capacity for benthic macroalgae to accumulate heavy metals from the environment was evaluated. Spatial differences in heavy metal concentration in both seawaters and sediments were observed at all sites with the highest concentrations of heavy metals including Cd (125 μg g^?1), Pb (2,425 μg g^?1) and Zn (7,974 μg g^?1) found in the finer sediment fractions (<250 μm) of Port Pirie. While all algal species studied (Acrosorium polyneurum, Anotrichium tenue, Cystophora Cephalornithos Cystophora monillifera, Cystophora monilliformis, Dictyopteris australis, Gelidium micropterum, Gracilaria, Hormophysa Cuneiformis, Sargassum cinctum, Scaberia agardhii and Ulva lactuca) accumulated metals to varying degrees, Blindigia marginata was a good biomonitor species for a number of metals including Cd, Co, Cr, Fe, Pb and Zn, exhibiting both relatively high total metal concentrations and significant concentration factors.     

Distribution and contamination assessment of toxic trace elements in sediment of the Daliao River System, China

The Daliao River System (DRS) is one of the major river systems in the northeastern China and receives substantial discharges from industrial, municipal, and agricultural effluents. In this study, the contents and partition of toxic trace elements in the DRS sediments were evaluated in terms of contamination levels and ecological risks using geoaccumulation index (Igeo), relative enrichment factor (REF), sediment pollution index (SPI), and potential effect concentration quotient (PECQ). Fourteen samples were collected and measured for trace and major elements and sediment properties. The following concentration ranges (mg kg^?1) of toxic trace elements were found: As, 1.6–18.0; Cd 0.1–0.9; Co 3.8–23.4; Cr 12.9–151.6; Cu 4.6–86.1; Hg 0.01–0.35; Ni 8.4–64.4; Pb 11.6–67.1; Sb 0.13–1.77; V 18.5–153.3; and Zn 20.4–211.3. The proportions of soluble and exchangeable trace metals were less than 1 %, while the proportions of trace metals bound to carbonate, amorphous oxides, organic matter, and crystalline oxides were usually each <10 %. However, 28.8 % of Cd, on average, was associated with carbonate. The average proportions of trace metals in the residual fraction ranged 57.3 % for Cd to 85.4 % for Cr, indicating low mobility and bioavailability. Cr, Ni, V, and Co in the sediments mainly originated from natural sources, while Cd, As, Pb, Sb, and Hg partially originated from anthropogenic sources. The Igeo, REF, SPI, and PECQ values of the heavy metals in the sediment were not in agreement with each another. The average REF values of Cd and As were higher than those of the other metals. However, the average PECQ value was higher for Cr and Ni than for the other metals, indicating that these two metals would cause higher adverse biological effects than the other metals. In addition, the sediments located adjacent to cities were more contaminated. Therefore, it is suggested that future management and pollution control within the DRS might focus on As, Cd, Cr, and Ni in the sediments, particularly in the sediments adjacent to cities.     

Anthropogenic versus natural control on trace element and Sr-Nd-Pb isotope stratigraphy in peat sediments of southeast Florida (USA), ∼1500 AD to present

Analysis of a well-dated peat core from Blue Cypress Marsh (BCM) provides a detailed record of natural and anthropogenic factors that controlled the geochemical cycles of a number of trace elements in Florida over the last five centuries. The trace elements were divided into “natural” and “anthropogenic” groups using concentration trends from the bottom to the top of the core. The “natural” group includes Li, Sc, Cr, Co, Ga, Ge, Zr, Nb, Cs, Ba, Hf, Y, Ta, Th, and REE (Rare Earth Elements). These elements show similar concentrations throughout the core, indicating that changes in human activities after European arrival in the “New World” did not affect their geochemical cycles. The “anthropogenic” group includes Pb, Cu, Zn, V, Sb, Sn, Bi, and Cd. Upcore enrichment of these elements indicates enhancement by anthropogenic activities. From the early 1500s to present, fluxes of the “anthropogenic” metals to the marsh increased significantly, with modern accumulation rates several-fold (e.g., V) to hundreds of times (e.g., Zn) greater than pre-colonial rates. The dominant input mechanism for trace elements from both groups to the marsh has been atmospheric deposition. Atmospheric input of a number of the elements, including the anthropogenic metals, was dominated by local sources during the last century. For several elements, long-distant transport may be important. For instance, REE and Nd isotopes provide evidence for long-range atmospheric transport dominated by Saharan dust.The greatest increase in flux of the “anthropogenic” metals occurred during the 20th century and was caused by changes in the chemical composition of atmospheric deposition entering the marsh. Increased atmospheric inputs were a consequence of several anthropogenic activities, including fossil fuel combustion (coal and oil), agricultural activities, and quarrying and mining operations. Pb and V exhibit similar trends, with peak accumulation rates in 1970. The principal anthropogenic source of V is oil combustion. The decline in V accumulation after 1970 in the BCM peat corresponds to the introduction of low-sulfur fuels and the change from heavy to distilled oils since the 1970s. After the 1920s, Pb distribution in the peat follows closely the history of alkyl lead consumption in the US, which peaked in the 1970s. Pb isotopes support this inference and furthermore, record changes in the ore sources used to produce leaded gasoline. Idaho ores dominated the peat Pb isotope record until the 1960s, followed by Pb from Mississippi Valley Type deposits from the 1960s to the 1980s. Enhanced fluxes of Cu, Zn, Cd, Sn, Sb, Bi, and to some extent Ni during the last century are likely also related to fossil fuel combustion. Local agricultural activities may also have influenced the geochemical cycles of Cu and Zn. The peat record shows enhanced U accumulation during the last century, possibly related to phosphate mining in western Florida. Sr isotopes in the peat core also reflect anthropogenic influence. The ⁸⁷Sr/⁸⁶Sr ratio decreases from natural background values in the basal part of the core to lower values in the upper part of the core. The Sr isotope shift is probably related to quarrying operations in Florida, and marks the first time an anthropogenic signal has been detected using the Sr isotope record in a peat core.     

Multivariate statistical approach to identify heavy metal sources in agricultural soil around an abandoned Pb–Zn mine in Guangxi Zhuang Autonomous Region, China

A study of agricultural lands around an abandoned Pb–Zn mine in a karst region was undertaken to (1) assess the distribution of heavy metals in the agricultural environment, in both dry land and paddy field; (2) discriminate between natural and anthropogenic contributions; and (3) identify possible sources of any pollution discovered. Ninety-two samples of cultivated soils were collected around the mine and analyzed for eight heavy metals, pH, fluoride (F^?), cation exchange capacity, organic matter, and grain size. The eight heavy metals included Cd, Cr, Cu, Ni, Pb, Zn, As, and Hg. The average concentrations (mg/kg) obtained were as follows: Cd 16.76 ± 24.49, Cr 151.5 ± 18.24, Cu 54.28 ± 18.99, Ni 57.5 ± 14.43, Pb 2,576.2 ± 1,096, Zn 548.7 ± 4,112, As 29.1 ± 6.36, and Hg 1.586 ± 1.46. In a site where no impact from mining activities was detected, the mean and median of Cd, Cu, Ni, Pb, Zn, As, and Hg concentrations in investigated topsoils were higher than the mean and median of heavy metal concentrations in reference soils. An ensemble of basic and multivariate statistical analyses was performed to reduce the multidimensional space of variables and samples. Two main sets of heavy metals were revealed as indicators of natural and anthropogenic influences. The results of principal component analysis (PCA) and categorical PCA demonstrated that Cd, Cu, Pb, Zn, and Hg are indicators of anthropogenic pollution, whereas Cr, As and Ni concentrations are mainly associated with natural sources in the environment. The contamination from Pb–Zn mining operations, coupled with the special karst environment, was a key contributing factor to the spatial distribution of the eight heavy metals in the surrounding soil. The values of heavy metals in the soil samples suggested the necessity of conducting a rigorous assessment of the health and environmental risks posed by these residues and taking suitable remedial action as necessary.     

Evaluation of trace element concentration (acid leachable) in sediments from River Pánuco and its adjacent lagoon areas, NE México

A set of forty-one surface sediment samples were collected in River Pánuco and its adjoining lagoon areas in NE Mexico to identify the enrichment pattern of trace elements. The samples were analyzed for sediment texture, carbonates, organic carbon and acid leachable trace elements (ALTEs) using autoclave method [Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, V, Be, Ba, Sr, As]. Geochemical results of Fe, Cr, Ni, Co, V and Sr in zone 1 indicate that erosion in the upland region (Sierra Madre Oriental Mountains) is very high. The above feature is supported by the supremacy of finer sediments (82.12 %), carbonates (44.67 %) and organic carbon (10.74 %), which are brought down from the drainage basin. The overall average concentration of ALTEs Mn (607 μg g^?1), Cu (28.29 μg g^?1), Ni (16.56 μg g^?1), Pb (46.11 μg g^?1), Cd (1.81 μg g^?1) and Zn (92.18 μg g^?1) indicates higher values than the lowest effect level (LEL) and effects range low (ERL) of environmental indicators. The results suggest that they are due to the increase in oil refineries, metal based industries, shipping activities and the effluent input which could enter the biological cycle and might create human health problems.     

An evaluation of trace metal distribution and environmental risk in sediments from the Lake Kalimanci (FYR Macedonia)

Pollution from mining activities is a significant problem in several parts of the Republic of Macedonia. A geochemical study of the surficial sediments of Lake Kalimanci in the eastern part of the Republic of Macedonia was carried out to determine their elemental compositions and to evaluate the pollution status of lake sediments by employing an enrichment factor (EF). The major and trace element contamination in surficial lake sediments was studied to assess the effects of metalliferous mining activities. The mean concentrations of major elements (wt%) Si 23.5, Al 7.9, Fe 6.6, Mg 1.3, Ca 3.8, Na 1.1, K 2.3, Ti 0.4, P 0.2, Mn 0.6 and trace elements ranged within Mo 1.0–4.6 mg kg^?1, Cu 144.4–1,162 mg kg^?1, Pb 1,874–16,300 mg kg^?1, Zn 2,944–20,900 mg kg^?1, Ni 21.7–79.3 mg kg^?1, Cd 16.5–136 mg kg^?1, Sb 0.6–3.6 mg kg^?1, Bi 3.0–24,3 mg kg^?1 and Ag 1.4–17.3 mg kg^?1. The EF ranged within 0.12–590.3. Among which, Cd, Pb, Zn and As have extremely severe enrichment. The data indicate that trace elements had extremely high concentrations in Lake Kalimanci surficial sediments owing to the anthropogenic addition of contaminants.     

Phytoremediation assessment of native plants growing on Pb–Zn mine site in Northern Tunisia

Pollution by heavy metals presents an environmental concern, and their toxicity threats soil, water, animals and human health. Phytoremediation can be used as a solution to remediate contaminated soils. The aim of this study was to identify native plants collected from tailings: material of Pb–Zn mine sites of Fedj Lahdoum and Jebel Ressas (two abandoned mines located, respectively, in the northwest of Tunisia and in the south of Tunis City). The tolerance of plant to heavy metals (lead, zinc and cadmium) is evaluated. Soil samples were collected and analyzed for Pb, Zn and Cd concentration. The total soil Pb, Zn and Cd are, respectively, reached 6132 mg kg^?1, 11,052 mg kg^?1 and it doesn’t exceed 479 mg kg^?1 for Cd. The highest content of Zn in plants was detected in shoots of Rumex bucephalophorus (1048 mg kg^?1), and the highest Pb concentration was detected in roots of Chrysopogon zizanioides (381 mg kg^?1), while for Cd Silene colorata it accumulated the highest content in roots (51 mg kg^?1). From all plants, only 12 have a translocation factor for Pb which is higher than one. Among all plants, only 17 have a translocation factor that is higher than one for Zn, while for Cd only 13 plants indicate TF > 1. As for the biological absorption coefficient, all samples indicate a rate which is lower than one. These plants can be primarily hyper accumulators and useful in remediation of lead- and zinc-contaminated soils after further biochemistry researches in mechanism of accumulation and translocation of heavy metals in plants.     

Multivariate statistical analysis of heavy metals in foliage dust near pedestrian bridges in Guangzhou, South China in 2009

The heavy metal content of particulate matter was investigated in the city of Guangzhou in southern China. Samples of urban foliage near 36 pedestrian bridges were analyzed to determine their Zn, Pb, Cu, Cr, V, Ni, and Co contents after digestion in a mixture of strong acids composed of HNO₃, HCl, HF, and HClO₄. The results revealed a severe heavy metal pollution compared with the background levels in Chinese soils, except for Co and V. The mean concentrations of Zn (1,024 mg kg^?1), Pb (233 mg kg^?1), Cu (203 mg kg^?1), Cr (118 mg kg^?1), V (41.9 mg kg^?1), Ni (41.4 mg kg^?1), and Co (11.3 mg kg^?1) in urban dust were higher than the reference levels, and were highest in samples located near high-traffic areas. Multivariate statistical methods (correlation analysis, principal-components analysis, and clustering analysis) were used to identify the possible sources of the metals. Three main pollutant sources are assigned: Zn, Cu and Ni levels were strongly correlated and were possibly related to combustion processes and vehicles; Pb, Cr and Co were mainly derived from traffic sources, combined with soil sources; and V mainly originated from natural sources.     

Toxic metal contamination and distribution in soils and plants of a typical metallurgical industrial area in southwest of China

In this work, the total and each fraction concentration of toxic metals (Pb, Zn, Cu and Cd) in soils as well as in plants from a typical metallurgical industrial area in southwest of China were determined. The obtained experimental results demonstrated that the total toxic metal content in contaminated soils was in the order of Zn > Pb > Cu > Cd. Modified microwave-assisted extraction showed that the distributions of each fraction of toxic metals in soils were different and some soil properties may play a role in the fraction distributions. The content of Cu, Zn, Cd and Pb in different vegetables ranged from 9.82 ± 1.02 to 39.3 ± 1.13 mg kg^?1, 1,321 ± 10.50 to 3,153 ± 11.30 mg kg^?1, 4.47 ± 0.21 to 18.9 ± 0.37 mg kg^?1 and 28 ± 1.2 to 102 ± 1.5 mg kg^?1, respectively. And the accumulation of toxic metals in plants was in the order of Cd > Zn > Cu > Pb. The bioconcentration factor (BCF) values of Cd, Zn, Cu and Pb in the different tissues of plants were in the range of 0.03–0.43, 0.027–0.35, 0.014–0.12 and 0.004–0.051, respectively. The distribution of each toxic metal in plants indicated that the ability for plants to accumulate toxic metals in different tissues followed the sequence of leaf > stem.     

Trace metals in Daihai Lake sediments, Inner Mongolia, China

A total of 29 surface sediments were collected from the Daihai Lake, China. Concentrations of metals (Cu, Pb, Zn, and Cd) were determined using HR-ICP-MS after digestion with the mixture of HNO₃–HF–HCl (aqua regia), and chemically fractionated according to the modified the European Community Bureau of Reference sequential extraction procedure. Total organic carbon contents and grain size were also analyzed. Average concentrations (ppm) for Cu (39.4 ± 10.6), Pb (29.9 ± 6.1), Zn (102.6 ± 23.3), and Cd (0.21 ± 0.07) were found in the sediments. The concentrations of metals are relatively higher in the central area of lake, while lower nearby the area with a shallower water depth. Sequential extraction results show that Cu and Zn are mainly distributed in the residual fraction, while Cd is dominantly in the non-residual fraction. Enrichment factor values and geoaccumulation indexes suggest that there are not obvious enrichments of Cu, Pb, and Zn in the sediments, but Cd pollution can be found in most of the area of Daihai Lake. The sources for Cu, Pb, and Zn are attributed to atmospheric deposition, which might be mainly associated with coal combustion. Agricultural runoff in polluted soils and coal combustion might be main sources of the Cd pollution in the lake.     

大庆市大气干湿沉降重金属元素通量及来源

大庆市是我国最大的陆上油田和重要的石油化工基地,开展重金属沉降通量及来源研究对于评估土壤重金属的来源及人类活动对土壤环境的影响具有重要意义。于2008年4月至次年4月采用被动采样技术共收集大气干湿沉降样品17份,配套土壤17份。通过AFS-230E原子荧光光度计法和ICP-AES全谱直读电感耦合等离子发射光谱法测试与分析了样品中的重金属含量,计算了沉降通量和富集因子。元素沉降通量与配套土壤的相关分析结果表明:Hg、Cd、As、Cr、Ni、Pb的沉降通量较低,而主要来源于人为污染源的Zn、Pb、As、Cd表现出较强或极强度的富集;土壤Zn、Cd的积累与大气沉降之间具有显著的相关关系。其他元素来源较为复杂,不同地区元素沉降通量之间差异显著。沉降量主要与城市地理位置、气候条件、人口数、工业结构、城市化水平等因素有关。     

南方某工业区大气总悬浮颗粒物重金属来源解析及其对土壤环境质量的影响

解析大气总悬浮颗粒物(TSP)的重金属来源可为重金属生态风险评价和环境修复提供理论依据。本文研究了中国南方某工业城市冶炼厂周边冬季TSP和表层土壤(0~20 cm)中的重金属环境效应。采用大气主动采样技术收集TSP样品,原子荧光光谱法和电感耦合等离子体质谱法测定其中重金属的含量,结合富集因子法和Pearson系数法分析重金属含量特征及其来源。结果表明,研究区TSP中Zn、Pb、Cd含量最高达到30809.06×10-6、9902.91×10-6、1011.21×10-6,分别是中国土壤背景值的201.43、222.53、5616.20倍,属于污染严重级别;Ni、Cr含量分别是中国土壤背景值的1.83倍和2.96倍。冶炼厂、火力发电厂和化工厂等人为源是Zn、Pb、Cd、Hg、As等重金属富集的主导因素;土壤重金属含量与TSP重金属含量呈显著正相关,可判定研究区土壤的重金属来源主要为大气沉降。     

Integrated mass balance of some heavy metals fluxes in Yaakob village,south Sohag,Egypt

The pollution of soil with heavy metals has direct or indirect adverse effect on human health. The present work was conducted to identify all the expected sources and sinks for heavy metals by applying mass balance model to identify the retention rate of metals by soils in Yaakob village, south Sohag Governorate, Egypt. The studied inputs (sources) include P-fertilizers, irrigation water and dustfall, while the main outputs (sinks) are drainage water and harvested plants. The measurements indicate that soil, clover, dustfall and P-fertilizers contain considerable concentration of Cd, Cr, Co, Cu and Pb. The mass balance measurements indicate that the accumulation rate of Cd, Cr and Co in soil was 5.4, 54.6 and 16.3 g ha^?1 year^?1, respectively. However, depletion trend of Pb and Cu was about 1.4 and 5.2 g ha^?1 year^?1, respectively. The main source of Cd, Pb, Cr and Co in the study area is P-fertilizers with input flux 14.9, 89.9, 198.6 and 18.5 g ha^?1 year^?1, while Cu source was dustfall with 19.33 g ha^?1 year^?1. The index of geoaccumulation calculations indicates different degrees of contamination with Cd, Cr, Co and Cu. On the other hand, the main sink for the studied heavy metals was the Egyptian clover (Trifolium alexandrinum) which can be considered a good bioaccumulator of heavy metals.