Contamination and potential mobility assessment of heavy metals in urban soils of Hangzhou,China: relationship with different land uses

Concentration and distribution of heavy metals (Cd, Cu, Pb and Zn) in urban soils of Hangzhou, China, were measured based on different land uses. The contamination degree of heavy metals was assessed on the basis of pollution index (PI), integrated pollution index (IPI) and geoaccumulation index (I _geo). The 0.1 mol l⁻¹ HCl extraction procedure and gastric juice simulation test (GJST) were used to evaluate the potential mobility and environmental risk of heavy metals in urban soils. The average concentration of Cd, Cu, Pb and Zn in urban soils was measured at 1.2 (with a range of 0.7–4.6), 52.0 (7.4–177.3), 88.2 (15.0–492.1) and 206.9 (19.3–1,249.2) mg kg⁻¹, respectively. The degree of contamination increased in the order of industrial area (IA) > roadside (RS) > residential and commercial areas (RC) > public park and green areas (PG). The PIs for heavy metals indicated that there is a considerable Cd, Cu, Pb and Zn pollution, which originate from traffic and industrial activities. The IPI of these four metals ranged from 1.6 to 11.8 with a mean of 3.5, with the highest IPI in the industrial area. The assessment results of I _geo also supported that urban soil were moderately contaminated with Cd and to a lesser extent also with Cu, Pb and Zn. The IP and I _geo values reveal the pollution degree of heavy metal was the order of Cd > Pb > Zn ≈ Cu. It was shown that mobility and bioavailability of the heavy metals in urban soils increased in the order of Cd > Cu > Zn ≈ Pb. Owing to high mobility of Cd and Cu in the urban soils, further investigations are needed to understand their effect on the urban environment and human health. It is concluded that industrial activities and emissions from vehicles may be the major source of heavy metals in urban contamination. Results of this study present a rough guide about the distribution and potential environmental and health risk of heavy metals in the urban soils.     

Heavy metal pollution in freshly deposited sediments of the Yamuna River (the Ganges River tributary): a case study from Delhi and Agra urban centres, India

 The Yamuna River sediments, collected from Delhi and Agra urban centres, were analysed for concentration and distribution of nine heavy metals by means of atomic adsorption spectrometry. Total metal contents varied in the following ranges (in mg/kg): Cr (157–817), Mn (515–1015), Fe (28,700–45,300), Co(11.7–28.4), Ni (40–538), Cu (40–1204), Zn (107–1974), Pb (22–856) and Cd (0.50–114.8). The degree of metal enrichment was compared with the average shale concentration and shows exceptionally high values for Cr, Ni, Cu, Zn, Pb and Cd in both urban centres. In the total heavy metal concentration, anthropogenic input contains 70% Cr, 74% Cu, 59% Zn, 46% Pb, 90% Cd in Delhi and 61% Cr, 23% Ni, 71% Cu, 72% Zn, 63% Pb, 94% Cd in Agra. A significant correlation was observed between increasing Cr, Ni, Zn, and Cu concentrations with increasing total sediment carbon and total sediment sulfur content. Based on the Müller's geoaccumulation index, the quality of the river sediments can be regarded as being moderately polluted to very highly polluted with Cr, Ni, Cu, Zn, Pb and Cd in the Delhi and Agra urban centres. The present sediment analysis, therefore, plays an important role in environmental measures for the Yamuna River and the planning of these city centres. Received: 21 June 1999 · Accepted: 1 October 1999     

Trace elements contamination of agricultural soils affected by sulphide exploitation (Iberian Pyrite Belt,Sw Spain)

Agricultural soils of the Riotinto mining area (Iberian Pyrite Belt) have been studied to assess the degree of pollution by trace elements as a consequence of the extraction and treatment of sulphides. Fifteen soil samples were collected and analysed by ICP-OES and INAA for 51 elements. Chemical analyses showed an As–Cu–Pb–Zn association related with the mineralisation of the Iberian Pyrite Belt. Concentrations were 19–994 mg kg⁻¹ for As, 41–4,890 mg kg⁻¹ for Pb, 95–897 mg kg⁻¹ for Zn and of 27–1,160 mg kg⁻¹ for Cu. Most of the samples displayed concentrations of these elements higher than the 90th percentile of the corresponding geological dominium, which suggests an anthropogenic input besides the bedrock influence. Samples collected from sediments were more contaminated than leptosols because they were polluted by leachates or by mining spills coming from the waste rock piles. The weathering of the bedrock is responsible for high concentrations in Co, Cr and Ni, but an anthropogenic input, such as wind-blown dust, seems to be indicative of the high content of As, Cu, Pb and Zn in leptosols. The metal partitioning patterns show that most trace elements are associated with Fe amorphous oxy-hydroxides, or take part of the residual fraction. According to the results obtained, the following mobility sequence is proposed for major and minor elements: Mn, Pb, Cd, > Zn, Cu > Ni > As > Fe > Cr. The high mobility of Pb, Cu and Zn involve an environmental risk in this area, even in soils where the concentrations are not so high.     

Status of anthropogenically induced metal pollution in the Kanpur-Unnao industrial region of the Ganga Plain, India

 The Ganga Plain is one of the most densely populated regions and one of the largest groundwater repositories of the Earth. For several decades, the drainage basin of the Ganga Plain has been used for the disposal of domestic and industrial wastes which has adversely affected the quality of water, sediments and agricultural soils of the plain. The concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn and organic carbon were determined in river sediments and soils of the Ganga Plain in the Kanpur-Unnao industrial region in 1994 and 1995 (pre-monsoon period of April–May). High contents (maximum values) of C-org (12.0 wt. %), Cr (3.40 wt. %), Sn (1.92 wt. %), Zn (4000 mg/kg), Pb (646 mg/kg), Cu (408 mg/kg), Ni (502 mg/kg) and Cd (9.8 mg/kg) in sediments (<20 μm fraction); and C-org (5.9 wt. %), Cr (2.16 wt. %), Sn (1.21 wt %), Zn (975 mg/kg) and Ni (482 mg/kg) in soils (<20 μm) in the pre-monsoon period of 1994 were found. From 1994 to 1995 the contents of Fe and Sn in sediments increase whereas those of C-org, Cd, Cu, Ni and Zn decrease. Considering the analytical errors, Al, Co, Cr, Mn and Pb do not show any change in their concentrations. In soils, the contents of Cd, Fe and Sn increase whereas those of Ni decrease from 1994 to 1995. Aluminium, Co, Cr, Cu, Mn, Pb and Zn do not show any change in their concentrations from 1994 to 1995. About 90% of the contents of Cd, Cr and Sn; 50–75% of C-org, Cu and Zn; and 25% of Co, Ni and Pb in sediments are derived from the anthropogenic input in relation to the natural background values, whereas in soils this is the case for about 90% of Cr and Sn; about 75% of Cd; and about 25% of C-org, Cu, Ni and Zn. The sediments of the study area show enrichment factors of 23.6 for Cr, 14.7 for Cd, 12.2 for Sn, 3.6 for C-org, 3.2 for Zn, 2.6 for Cu and 1.6 for Ni. The soils are enriched with factors of 10.7 for Cr, 9.0 for Sn, 3.6 for Cd, 1.8 for Ni and 1.5 for Cu and Zn, respectively. Received: 3 March 1998 · Accepted: 15 June 1998     

Heavy metals pollution in the soil of an irregular urban settlement built on a former dumpsite in the city of Tijuana, Mexico

The aim of this study was to evaluate soil pollution by heavy metals in an irregular settlement built on a dumpsite. The soil samples were analyzed for Cd, Cr, Cu, Pb and Ni. None of the concentrations found for the heavy metals analyzed were higher than the established Mexican official standards for contaminated soils. The mean concentrations found for the analyzed metals were as follows: 1.4 mg kg⁻¹ for Cd, 4.7 in mg kg⁻¹ for Cr, 304 mg kg⁻¹ for Cu, 74 mg kg⁻¹ for Pb and 6 mg kg⁻¹ for Ni. The results of the geoacummulation index values show that the site was very polluted with Cu and Pb (class 7), polluted to strongly polluted with Ni (class 4); moderately polluted to polluted with Cd (class 3), and moderately polluted with Cr (class 1). The correlation analysis shows a high correlation between Pb and Cu (r ² = 0.98), which would be explained if the main source of the polluting heavy metals was the result of electrical wire burning to recover Copper. Principal component analysis shows three principal components. The first main component (PC1) encompasses Cr, Cd, Pb and Cu. These heavy metals most likely have their origins from the open burning of municipal solid waste, tires and wire. The other two components are encompassed by Cr (PC2) and Ni (PC3). The sources of these pollutants are more likely related to the corrosion of junk metal objects and automobile use.     

Mobility and ecological risk assessment of heavy metals in surface sediments of Xiamen Bay and its adjacent areas,China

Xiamen Bay (XMB) has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1980s. To assess ecological risks and the current spatial changes of metal contaminants in bottom surface sediments, 12 samples were collected. Samples were subjected to a total digestion technique and analyzed by ICP–OES for Cu, Pb, Zn, Cr, and Cd, and by AFS for Hg and As. Among these metals, Zn had the highest values (68–268 mg kg⁻¹), followed by Pb (27–71 mg kg⁻¹), and lower concentrations were found for Cd (42–1,913 μg kg⁻¹) and Hg (0–442 μg kg⁻¹). In comparison with the average crustal abundance values, the results indicated that nearly half of the sediment samples of XMB and its adjacent areas were contaminated by Cd, Pb, Zn, and As. Furthermore, based on the modified BCR sequential extraction procedure, the chemical speciation of heavy metals (Cd, Cr, Cu, Pb, Zn, Hg, and As) in selected sediment samples were evaluated in this study. Data from BCR sequential extractions indicated that Cd posed a medium ecological risk, whereas, Cr posed low risk since its exchangeable and carbonate fractions were below 4%, and the mobility of heavy metals in XMB decreased in the order Cd > Pb > Cu > Zn > Hg > As > Cr. By applying mean effects range median quotients (mERMQ), the results showed that Yuandang Lagoon with mERMQ value >0.5 would be expected to have the greatest potential toxic risk in amphipod within XMB and its adjacent areas.     

Impact of historical metalworks on the concentrations of major and trace elements in sediments: a case study in Finland

The concentrations of major and trace elements were determined (aqua regia leach and ICP-AES analyses) in stream, lake and dredged sediments downstream of the historical Antskog iron- and copperworks, S.Finland. The levels of Ag, Cd, Cu, Pb and Zn are highly elevated in all studied sediment types: roughly half of the studied lake-sediment samples contain >5 ppm Ag, >15 ppm Cd, >0.1% Cu, >0.1% Pb and >0.3% Zn. In the dredged sediment material located onshore, the concentrations of Ag, Cu and Pb are comparable to those in the polluted lake-sediment samples, while in stream sediments elevated metal concentrations are found especially in samples characterised by high concentrations of organic material. The source of the elevated metal concentrations is the historical metalworks at Antskog, mainly the copperworks of the 19th century. Compared to the limit values for contaminated soils in Finland, the concentrations of Cu, Pb and Zn are on average elevated by factors >10 in the polluted horizons of lake sediments, >5 in the dredged sediment located onshore and >2 at the most heavily contaminated site in the stream. Since the surface waters in the area are used for agricultural purposes and for various leisure activities, it is necessary to make further detailed investigations into the extent of the metal pollution and to determine species, mobility and bioavailability of the metals.     

Immobilization of heavy metals in a contaminated soil in Iran using di-ammonium phosphate,vermicompost and zeolite

Fractionation of heavy metals (HMs) in amended soils is needed to predict elemental mobility in soil and phytoavailability to plants. A study was conducted to determine the effects of different amendments on HMs availability and their redistribution among soil fractions. A contaminated soil was selected from around a Zn mine and amended with 0, 2, 4, and 6 g kg⁻¹ of vermicompost (VC), zeolite (ZE), and di-ammonium phosphate (DP) and incubated at field moisture. The amounts of Cd, Pb, Zn, and Cu were determined from the soil after 6 months of incubation time using DTPA and sequential extraction procedures. The total concentrations of Cd, Pb, Zn, and Cu were 41, 3,099, 1,997, and 83 mg kg⁻¹ of soil, respectively. All amendments decreased significantly [probability (p) ≤ 0.05] DTPA-extractable Cd, Pb, and Cu, but not Zn, in the soil. For instance, DTPA-extractable Cd, Pb, and Cu decreased by 40, 290, and 20%, respectively, and that of Zn increased by 18% with DP₁ (2 g kg⁻¹ of di-ammonium phosphate) application. The concentrations of Pb and Cd decreased mainly in the specifically sorbed (SS) but increased in the amorphous Fe oxide (AFeO) fraction with DP application, indicating redistribution of Pb and Cd in the fractions with less mobility. Lead immobilization by DP was mainly attributed to the P-induced formation of chloropyromorphite, which was identified in the DP treatment using X-ray diffraction technique. It was concluded that DP was the most effective amendment in immobilizing Pb and Cd, though it increased Zn mobility.     

Distribution and immobilization of heavy metals in Pliocene aquifer sediments in Wadi El Natrun depression, Western Desert

The Pliocene aquifer receives inflow of Miocene and Pleistocene aquifer waters in Wadi El Natrun depression. The aquifer also receives inflow from the agricultural activity and septic tanks. Nine sediment samples were collected from the Pliocene aquifer in Wadi E1 Natrun. Heavy metal (Cu, Sr, Zn, Mn, Fe, Al, Ba, Cr, Ni, V, Cd, Co, Mo, and Pb) concentrations of Pliocene aquifer sediments were investigated in bulk, sand, and mud fractions. The determination of extractable trace metals (Cu, Zn, Fe, Mn, and Pb) in Pliocene aquifer sediments using sequential extraction procedure (four steps) has been performed in order to study environmental pathways (e.g., mobility of metals, bounding states). These employ a series of successively stronger chemical leaching reagents which nominally target the different compositional fractions. By analyzing the liquid leachates and the residual solid components, it is possible to determine not only the type and concentration of metals retained in each phase but also their potential ecological significance. Cu, Sr, Zn, Mn, Fe, and Al concentrations are higher in finer sediments than in coarser sediments, while Ba, Cr, Ni, V, Cd, Co, Mo, and Pb are enriched in the coarser fraction. The differences in relative concentrations are attributed to intense anthropogenic inputs from different sources. Heavy metal concentrations are higher than global average concentrations in sandstone, USEPA guidelines, and other local and international aquifer sediments. The order of trace elements in the bulk Pliocene aquifer sediments, from high to low concentrations, is Fe?>?Al?>?Mn?>?Cr?>?Zn?>?Cu?>?Ni?>?V?>?Sr?>?Ba?>?Pb?>?Mo?>?Cd?>?Co. The Pliocene aquifer sediments are highly contaminated for most toxic metals, except Pb and Co which have moderate contamination. The active soluble (F0) and exchangeable (F1) phases are represented by high concentrations of Cu, Zn, Fe, and Mn and relatively higher concentrations of Pb and Cd. This may be due to the increase of silt and clay fractions (mud) in sediments, which act as an adsorbent, retaining metals through ion exchange and other processes. The order of mobility of heavy metals in this phase is found to be Pb?>?Cd?>?Zn?>?Cu?>?Fe?>?Mn. The values of the active phase of most heavy metals are relatively high, indicating that Pliocene sediments are potentially a major sink for heavy metals characterized by high mobility and bioavailability. Fe–Mn oxyhydroxide phase is the most important fraction among labile fractions and represents 22% for Cd, 20% for Fe, 11% for Zn, 8% for Cu, 5% for Pb, and 3% for Mn. The organic matter-bound fraction contains 80% of Mn, 72% of Cu, 68% of Zn, 60% of Fe, 35% of Pb, and 30% of Cd (as mean). Summarizing the sequential extraction, a very good immobilization of the heavy metals by the organic matter-bound fraction is followed by the carbonate-exchangeable-bound fraction. The mobility of the Cd metal in the active and Fe–Mn oxyhydroxide phases is the highest, while the Mn metal had the lowest mobility.     

Heavy metals in freshly deposited sediments of the Gomati River (a tributary of the Ganga River): effects of human activities

 The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river. Received: 16 February 1996 · Accepted: 29 February 1996     

Chemodynamics of trace metal fractions in surface sediments of the Pandoh Lake,Lesser Himalaya,India

The seasonal variation in the trace metals’ concentrations (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) were investigated in surface sediments of the Pandoh Lake. The horizontal distribution of TC, TN, and TP reflects spatial and temporal differences in sedimentary organic production. The chemical sequential extraction of heavy metals was carried out by seven-step fractionation scheme (Leleyter and Probst in Int J Environ Chem 73:109–128, 1999). The significant concentrations of Ni and Cd were associated with “water soluble (Eua)” fraction in the monsoon and winter, respectively, while “exchangeable (Exch)” and “carbonate-bound (Carb)” fractions for Ni and Cd were abundant in winter and summer. The Cd, Cu, and Pb associated with “Exch” fraction in the summer season support their availability on exchange sites due to oxidized nature of surface sediments. Enrichment of Co, Fe, Mn, and Zn in “AFeO” fraction showed poor bioavailability, while Cd, Cu, and Mn in the monsoon, Co in the winter and summer, and Zn in the winter season showed significant “organically bound (Org)” fraction. The ANOVA was significant for chemical fractions of trace elements except “Carb” fraction of Pb and Zn and “CFeO” fraction of Pb. Factor analysis revealed that the “Eua”, “Exch”, and “Carb” fractions together control the metal enrichment of “MnO”, “AFeO”, and “CFeO” fractions in the summer season.     

Competitive adsorption of trace elements in calcareous soils as affected by sewage sludge,poultry manure,and municipal waste compost

The competitive adsorption of trace elements is a key issue in assessing the mobility of trace elements in calcareous soils and can be affected by disposal of sewage sludge, municipal waste, and poultry manure. The effect of municipal sewage sludge, poultry manure, and municipal waste compost on the sorption of cadmium (Cd), copper (Cu), zinc (Zn), and nickel (Ni) in surface samples of three calcareous soils was studied. As the applied concentrations increased, Cu and Cd adsorption increased, while Zn and Ni adsorption decreased in all treatments. Based on the distribution coefficient (K _d) values and proportion of increase or decrease in metal adsorption, the selectivity sequence in control and amended soils found was Cu ≫ Cd ≫ Ni > Zn and Cu ≫ Cd ≫ Zn > Ni, respectively. In general, among control and amended soils, control soils showed the highest K _d for Cd, Cu, and Ni, while sludge, poultry manure, and composted waste-amended soils had lowest K _d for Cd, Cu, and Ni, respectively. In the case of Zn, composted waste-amended and control soils had highest and lowest K _d, respectively. The present experimental results indicated that the addition of organic amendments to these calcareous soils reduced the sorption of Cd, Cu, and Ni. Thus, the effects of preferential adsorption and organic matter should be considered in assessing the risk associated with applying sewage sludge, poultry manure, and composted material to calcareous soils.     

Contamination,chemical speciation and vertical distribution of heavy metals in soils of an old and large industrial zone in Northeast China

Heavy metal pollution of soils has become a major concern in China as a consequence of rapid urbanization and industrialization in recent years. However, the evaluation on soil heavy metal pollution in Shenyang, the largest heavy industrial base city in China, has not yet been conducted. In this study, accumulation, chemical speciation, and vertical distribution Cu, Zn, Pb and Cd in soils were studied and pollution condition was assessed in Tiexi Industrial District of Shenyang, the largest and oldest industrial zone in Northeastern China. The results showed that in topsoil, the average concentration of total Cu, Zn, Pb, and Cd was 209.06, 599.92, 470.19 and 8.59 mg kg⁻¹, respectively, much higher than the national threshold limit. The values of pollution index and integrated pollution index showed that the pollution level was Cd > Cu > Zn > Pb, and Cd, Cu and Zn belong to heavy pollution level. The residual, Fe and Mn oxide-bound, and organic-bound species accounted for about 90%, while carbonate-bound and exchangeable species accounted for about 10%. This study indicates that the soils in the industrial zone were widely and extremely polluted by multi-heavy metals as a result of long-term industrial activities.     

Geochemistry of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan Province (P. R. China): implications on sources of trace metals

This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and Sn are extremely highly enriched (EF values >40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones (PL), and metals of anthropogenic sources were contributed from Pb–Zn ore deposits distributed in upper river areas. Metals in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts. Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting, and refining) of Pb–Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60–85%, with natural proportion higher than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30–70%, with natural contribution higher than 30%. Metals Ba, V and Mo might be contributed mostly from natural process.     

Transport and sediment–water partitioning of trace metals in acid mine drainage: an example from the abandoned Kwangyang Au–Ag mine area, South Korea

Transport and sediment–water partitioning of trace metals (Cr, Co, Fe, Pb, Cu, Ni, Zn, Cd) in acid mine drainage were studied in two creeks in the Kwangyang Au–Ag mine area, southern part of Korea. Chemical analysis of stream waters and the weak acid (0.1 N HCl) extraction, strong acid (HF–HNO₃–HClO₄) extraction, and sequential extraction of stream sediments were performed. Heavy metal pollution of sediments was higher in Chonam-ri creek than in Sagok-ri creek, because there is a larger source of base metal sulfides in the ores and waste dump upstream of Chonam-ri creek. The sediment–water distribution coefficients (K _d) for metals in both creeks were dependent on the water pH and decreased in the order Pb ≈ Al > Cu > Mn > Zn > Co > Ni ≈ Cd. K _d values for Al, Cu and Zn were very sensitive to changes in pH. The results of sequential extraction indicated that among non-residual fractions, Fe–Mn oxides are most important for retaining trace metals in the sediments. Therefore, the precipitation of Fe(–Mn) oxides due to pH increase in downstream sites plays an important role in regulating the concentrations of dissolved trace metals in both creeks. For Al, Co, Cu, Mn, Pb and Zn, the metal concentrations determined by 0.1 N HCl extraction (Korean Standard Method for Soil Pollution) were almost identical to the cumulative concentrations determined for the first three weakly-bound fractions (exchangeable + bound to carbonates + bound to Fe–Mn oxides) in the sequential extraction procedure. This suggests that 0.1 N HCl extraction can be effectively used to assess the environmentally available and/or bioavailable forms of trace metals in natural stream sediments.     

Distribution of Cd,Pb, Zn and Cu and their chemical speciations in soils from a peri-smelter area in northeast China

An exploratory study on soil contamination of heavy metals was carried out surrounding Huludao zinc smelter in Liaoning province, China. The distribution of total heavy metals and their chemical speciations were investigated. The correlations between heavy metal speciations and soil pH values in corresponding sites were also analyzed. In general, Cd, Zn, Pb, Cu and As presented a significant contamination in the area near the smelter, comparied with Environmental Quality Standards for Soils in China. The geoaccumulation index showed the degree of contamination: Cd > Zn > Pb > Cu > As. There was no obvious pollution of Cr and Ni in the studied area. The speciation analysis showed that the dominant fraction of Cd and Zn was the acid soluble fraction, and the second was the residual fraction. Pb was mostly associated with the residual fraction, which constituted more than 50% of total concentration in all samples. Cu in residual fraction accounted for a high percentage (40–80%) of total concentration, and the proportion of Cu in the oxidizable fraction is higher than that of other metals. The distribution pattern of Pb and Zn was obviously affected by soil pH. It seemed that Pb and Zn content in acid solution fraction increased with increasing soil pH values, while Cd content in acid soluble fraction accounted for more proportion in neutral and alkaline groups than acidic one. The fraction distribution patterns of Cu in three pH groups were very similar and independent of soil pH values. And the residual fraction of Cu took a predominant part (50%) of the total content.     

Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia)

Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg⁻¹, Pb: 28.5–67.3 mg kg⁻¹, Zn: 17.0-65.4 mg kg⁻¹, Cu: 21.1–51.9 mg kg⁻¹, Ni: 27.8–40.2 mg kg⁻¹) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.     

The influence of physicochemical parameters on bioavailability and bioaccessibility of heavy metals in sediments of the intertidal zone of Asaluyeh region,Persian Gulf,Iran

In this research, we have worked on the evaluation of heavy metal contamination in the sediments taken from the intertidal zone of Asaluyeh region using Modified Community Bureau of Reference sequential extraction method (mBCR), the simplified bioaccessibility extraction test (SBET), and calculated enrichment factor (EF). Also, potential influencing factors including sediment characteristics that may affect the heavy metals bioavailability and bioaccessibility were investigated. mBCR extraction analysis indicated that among the metals, Mn, Zn, V, Cu, and Cd exhibit relatively higher mobility, while Ti, Pb, Cr, and Ni occur mainly in the residual fractions. Based on the mean values, the bioaccessibility of metals decreased in the order: Mn (50.01%)>Cd (46.26%)>Zn (14.61%)>V (13.97%)>Pb (10.88%)>Ni (9.2%)>Ti (8.43%)>Cr (6.66%)>Cu (6.23%). The obtained results from the principal component analysis (PCA), EF and mBCR extraction showed that most anthropogenic-derived metals with higher solubility are more bioaccessible compared to those of natural origin. Multiple linear regression analysis demonstrated that the main physicochemical variables of the sediment influencing the bioaccessibility of metals include cation exchange capacity (CEC), pH, and particle size fraction.     

Heavy meals in urban roadside soils, part 1: effect of particle size fractions on heavy metals partitioning

Urban roadside soils are important environmental media for assessing heavy metal concentrations in urban environment. However, among other things, heavy metal concentrations are controlled by soil particle grain size fractions. In this study, two roadside sites were chosen within the city of Xuzhou (China) to reflect differences in land use. Bulk soil samples were collected and then divided by particle diameter into five physical size fractions, 500–250, 250–125, 125–74, 74–45, < 45 μm. Concentrations of metals (Ti, Cr, Al, Ga, Pb, Ba, Cd, Co, Cu, Mn, Ni, V, Zn, Mo, As, Sb, Se, Hg, Bi, Ag) were determined for each individual fraction. These metals could be roughly classified into two groups: anthropogenic element (Pb, Ba, Cd, Cu, Zn, Mo, As, Sb, Se, Hg, Bi, Ag) and lithophile element (Ti, Cr, Al, Ga, Co, Mn, Ni, V) in terms of values of enrichment factor. As expected, higher concentrations of anthropogenic heavy metals (Cu, Zn, Mo, As, Hg, Bi, Ag) are observed in the finest particle grain size fraction (i.e. < 45 μm). However, heavy metals Se, Sb and Ba behave independently of selected grain size fractions. From the viewpoint of mass loading, more than 30% of the concentrations for all anthropogenic heavy metals are contributed by the particle grain size fractions of 45–74 μm at site 1 and more than 70% of the concentrations for all heavy metals are contributed by the particle grain size fractions of 45–74 and 74–125 μm at site 2. These results are important for transport of soil-bound heavy metals and pollution control by various remedial options.     

Assessment of heavy metal contamination in soils around Balanagar industrial area,Hyderabad, India

The concentration of heavy metals such as Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn, Zr were studied in soils of Balanagar industrial area, Hyderabad to understand heavy metal contamination due to industrialization and urbanization. This area is affected by the industrial activities like steel, petrochemicals, automobiles, refineries, and battery manufacturing generating hazardous wastes. The assessment of the contamination of the soils was based on the geoaccumulation index, enrichment factor (EF), contamination factor, and degree of contamination. Soil samples were collected from Balanagar industrial area from top 10–50 cm layer of soil. The samples were analyzed using X-ray fluorescence spectrometer for heavy metals. The data revealed that the soils in the study area are significantly contaminated, showing high level of toxic elements than normal distribution. The ranges of concentration of Cr (82.2–2,264 mg/kg), Cu (31.3–1,040 mg/kg), Ni (34.3–289.4 mg/kg), Pb (57.5–1,274 mg/kg), Zn (67.5–5819.5 mg/kg), Co (8.6–54.8 mg/kg), and V (66.6–297 mg/kg). The concentration of above-mentioned other elements was similar to the levels in the earth’s crust pointed to metal depletion in the soil as the EF was <1. Some heavy metals showed high EF in the soil samples indicating that there is a considerable heavy metal pollution, which could be correlated with the industries in the area. A contamination site poses significant environmental hazards for terrestrial and aquatic ecosystems. They are important sources of pollution and may results in ecotoxicological effects on terrestrial, groundwater and aquatic ecosystems.