Pollution assessment and spatial variation of soil heavy metals in Lixia River Region of Eastern China

Purpose

The effect of soil heavy metals on crops and human health is an important research topic in some fields (Agriculture, Ecology et al.). In this paper, the objective is to understand the pollution status and spatial variability of soil heavy metals in this study area. These results can help decision-makers apportion possible soil heavy metal sources and formulate pollution control policies, effective soil remediation, and management strategies.

Materials and methods

A total of 212 topsoil samples (0–20 cm) were collected and analyzed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn, and Ni) from agricultural areas of Yingbao County in Lixia River Region of Eastern China, by using four indices (pollution index (PI), Nemerow pollution index (PI_N), index of geo-accumulation (I _geo), E _i /risk index (RI)) and cluster analysis to assess pollution level and ecological risk level of soil heavy metals and combining with geostatistics to analyze the concentration change of heavy metals in soils. GS+ software was used to analyze the spatial variation of soil heavy metals, and the semi-variogram model is the main tool to calculate the spatial variability and provide the input parameters for the spatial interpolation of kriging. Arcgis software was used to draw the spatial distribution of soil heavy metals.

Results and discussion

The result indicated that the eight heavy metals in soils of this area had moderate variations, with CVs ranging from 23.51 to 64.37 %. Single pollution index and Nemerow pollution index showed that about 2.7 and 1.36 % of soil sampling sites were moderately polluted by Cd and Zn, respectively. The pollution level of soil heavy metals decreased in the order of Cd?>?Zn?>?Pb?>?As?>?Cu?>?Cr?>?Ni?>?Hg. The I _geo values of heavy metals in this area decreased in the order of Zn?>?Cd?>?As?>?Pb?>?Cu?>?Cr?>?Hg?>?Ni. According to the E _i index, except Cd that was in the moderate ecological risk status, other heavy metals in soils were in the light ecological risk status, and the level of potential ecological risk (RI) of soil sampling sites of the whole area was light.

Conclusions

The results of four indices and the analysis of spatial variation indicated that the contents of Cd and Zn were contributed mainly by anthropogenic activities and located in the south-east of this study area. However, the contents of Hg, As, Cu, Pb, Cr, and Ni in soils were primarily influenced by soil parent materials.

     

Identifying the Sources and Contamination Status of Potentially Toxic Trace Elements in Agricultural Soils

Elevated concentrations of potentially toxic trace elements in agricultural soils contribute to soil pollution affecting food quality and safety. We assessed pollution levels in agricultural systems, lowland rice (LL) and highland cash crops (HL), by comparing with non-agricultural soils (NA). Correlation analysis and principal component analysis (PCA) were performed, and geo-accumulation index (I_geo) and pollution loading index (PLI) were calculated. Zinc in LL, and Cd in LL and HL, were significantly higher than in NA. The I_geo values of cooper (Cu), lead (Pb), nickel (Ni), zinc (Zn), and cadmium (Cd) ranged from uncontaminated to moderately contaminated (Class 0 to 2) for LL, HL, and NA. Overall, trace element levels were categorized as unpolluted based on PLI. Soil properties significantly correlated with Cu, Pb, Ni, and Zn concentrations but not with Cd. Based on PCA, sources of origin for Cu, Pb, Ni, and Zn were lithogenic, while the sources for Cd was anthropogenic in the studied agricultural soils.     

Evaluation and source identification of trace element contamination of soils in the Qixia lead-zinc mining area,Jiangsu, China

Purpose

The Qixia mine is one of the largest lead-zinc mines in Eastern China and has been operational for approximately 60 years. Source identification for trace element contamination of soils in the Qixia mining area has been lacking. This report details the evaluation and source identification of trace element contamination (including Cu, Zn, Pb, Cd, Hg, Cr, As, and Ni) of soils in this area.

Materials and methods

Thirty-three soil samples from roadsides and fields in the study area were collected and analyzed. The index of geo-accumulation (I _geo) was employed to evaluate contamination. Methods of multivariate statistical analysis were used to determine the probable sources of the pollutants.

Results and discussion

The analysis showed that the levels of contamination ranked in the following order: Cd > Pb/Zn> > As/Cu> > Hg > Cr/Ni. In the sampling area nearest the mine, soil samples collected from roadsides showed much higher levels of contamination than those collected from fields away from the roadways. Trace element contamination decreased as the distance from the mine increased. Contamination extended to a distance of approximately 700 m from mineral transportation routes, with the area of greatest impact at 200 m or less. Multivariate statistical analysis and ore composition data suggest that the Cu, Zn, Pb, Cd, and As found in the soil samples originate from anthropogenic sources. Ni and Cr are considered to be at natural background concentrations.

Conclusions

This study distinguished between natural and anthropogenic sources of trace element contamination in the soils of the Qixia mining area. The contamination of Cu, Zn, Pb, Cd, and As is linked to the mining activities and is likely due to the transportation of ore concentrates and tailings.     

Contents and chemical forms of heavy metals in school and roadside topsoils and road-surface dust of Beijing

Purpose

The concentration of human activities in urban systems generally leads to urban environmental contamination. Beijing is one of ancient and biggest cities on the world. However, information is limited on Beijing’s soil contamination, especially for roadside and campus soils. Thus, the aims of this study were to investigate the contents and chemical forms of toxic heavy metals Cd, Cr, Cu, Ni, Pb, and Zn in the road-surface dust, roadside soils, and school campus soils of Beijing. In addition, enrichment and spatial variation of these toxic heavy metals in the soils and dust were assessed.

Materials and methods

Topsoil samples were collected from the schools and roadside adjacent to main ring roads, and dust samples were collected from the surface of the main ring roads of Beijing. These samples were analyzed for total contents and chemical forms of Cd, Cr, Cu, Ni, Pb, Sc, Zn, Al, and Fe. Enrichment factors (EFs, relative to the background content) were calculated to evaluate the effect of human activities on the toxic heavy metals in soils.

Results and discussion

Heavy metal contents in the road dust ranged from 0.16 to 0.80, 52.2 to 180.7, 18.4 to 182.8, 11.9 to 47.4, 23.0 to 268.3, and 85.7 to 980.9 mg kg^?1 for Cd, Cr, Cu, Ni, Pb, and Zn, respectively. In the roadside soil and school soil, Cd, Cr, Cu, Ni, Pb, and Zn contents ranged from 0.13 to 0.42, 46.1 to 82.4, 22.7 to 71.6, 20.7 to 29.2, 23.2 to 180.7, and 64.5 to 217.3 mg kg^?1, respectively. The average EF values of these metals were significantly higher in the dust than in the soils. In addition, the average EF values of Cd, Cu, Pb, and Zn in the soils near second ring road were significantly higher than those near third, fourth, and fifth ring roads. Anthropogenic Cd, Pb, and Zn were mainly bound to the carbonates and soil organic matter, while anthropogenic Cu was mainly bound to oxides. The mobility and bioavailability of these metals in the urban soils of Beijing generally decreased in the following order: Cd?>?Zn?>?Pb?>?Cu?>?Ni?>?Cr; while in the dust, they decreased in the following order: Zn, Cu, and Cd?>?Pb?>?Ni?>?Cr.

Conclusions

Both EF and chemical forms documented that Cr and Ni in the soils and dust mainly originated from native sources, while Cd, Cu, Pb, and Zn partially originated from anthropogenic sources. In overall, Beijing’s road dust was significantly contaminated by Cd and Cu and moderately contaminated by Cr, Pb, and Zn, while Beijing’s roadside soil and school soil were moderately contaminated by Cd and Pb. However, the maximal hazard quotients (HQs) for individual Cd, Cr, Cu, Ni, Pb, and Zn and comprehensive hazard index (HI) of these metals in the dust and soil were less than 1, indicating that the heavy metals in the dust and soil generally do not pose potential health effects to children, sensitive population.     

Geochemical monitoring of organic and inorganic pollutants in the sediment of the Eastern Posavina (Serbia)

Purpose

The aim of this study was to obtain a complete picture of the geochemical character of the sediment in the eastern Posavina region, Serbia, an area which has thus far not been systematically investigated. Geological mapping and impact assessment were thus carried out for this area.

Materials and methods

Sediments were sampled (from 0 to 0.5 m depth) in four locations in eastern Posavina between 2002 and 2014. Eight heavy metals (Ni, Zn, Cd, Cr, Cu, Pb, As and Hg) and a wide variety of organic parameters (16 EPA polycyclic aromatic hydrocarbons (PAHs), mineral oils, selected pesticides and polychlorinated biphenyls (PCBs)) were monitored. Metals were analysed by flame and graphite atomic absorption spectrometry, and gas chromatography with mass detection was used for the PAH analyses. The origins of the monitored substances were classified using geoaccumulation index (I _geo), ecological risk index (RI) and principal component analysis (PCA/FA).

Results and discussion

The sediments all contained higher heavy metals concentrations than the upper continental crust (UCC), suggesting dynamic natural and anthropogenic processes in this unique region. Significant variations (RSD values from 13 to 190) were observed for Cd (0.001–80.00 mg kg^?1), Hg (0.01–5.40 mg kg^?1), mineral oil (2.00–1851 mg kg^?1) and the sum of 16 EPA PAHs (0.003–5.57 mg kg^?1). The I _geo index classified the pollution risk due to Cr as strong, Cd, Zn and Hg as moderate to strong and Ni as moderate. Based on PCA/FA analysis, the parameters were grouped somewhat differently, with anthropogenic activity found to be responsible for much of the Hg, Cd and Cr pollution present in the sediments.

Conclusions

The analysis revealed eight heavy metals (Ni, Zn, Cd, Cr, Cu, Pb, As and Hg), the sum of 16 EPA PAHs and mineral oil as parameters of great interest for this unique region. These parameters must be the focus of future monitoring programs, in support of appropriate remediation techniques and/or dredging activities, which are required in order to comply with the new Serbian regulations and the relevant EU recommendations.

     

Trace metals in sediments and aquatic plants from the Xiangjiang River, China

Purpose

The metal concentrations and Pb isotopic composition in sediments and plants from the Xiangjiang River, China, were investigated to understand the contamination and potential toxicity of metals in sediments; to determine the accumulation and distribution of metals in plant tissues; and to trace the possible pollution source of Pb in sediments and plants.

Materials and methods

Sediments and plants were collected from 43 sampling sites in the study region. After sediments were air-dried and passed through a 63-??m sieve, they were acid-digested and DTPA-extracted for determination of total and bioavailable metals. The plants were separated into roots, leaves, and stems; dried; cut into pieces; and digested with HNO₃?CH₂O₂. Metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) and Pb isotopic composition were analyzed by inductively coupled plasma-mass spectrometry.

Results and discussion

Maximum As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in sediments were 47.18, 55.81, 129.5, 161.6, 160.4, 430.7, and 1,098.8?mg?kg^?1, respectively. The bioavailable fractions of As, Cd, Cu, Pb, and Zn had significant linear relationship with their corresponding total contents in sediments while no significant relationship was observed between bioavailable and total contents of Cr and Ni. In general, plant tissues showed higher As, Cd, Cu, Pb, and Zn concentrations and lower Cr and Ni concentrations compared with sediments. The ²⁰⁶Pb/²⁰⁷Pb ratios decreased in the order of total > bioavailable > stems ?? leaves > roots. A strong linear correlation was observed between the ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁷Pb ratios of the plant tissues, sediments, and the possible pollution sources of Pb in the Xiangjiang River.

Conclusions

As, Cd, Cu, Pb, and Zn demonstrated higher contamination levels in sediments and plants compared with Cr and Ni. Cd had highest potential ecological risk. The Pb from anthropogenic sources with low ²⁰⁶Pb/²⁰⁷Pb ratios was preferentially associated with the bioavailable fractions in sediments and accumulated in roots. The Pb in plant tissues is mainly derived from the Pb in sediment and is taken up through the sediment-to-root pathway.     

Spatial distribution and source apportionment of the heavy metals in the agricultural soil in a regional scale

Purpose

Understanding the spatial distribution and sources of soil heavy metals (HMs) in a large city helps prevent and control soil pollution. This study aimed to investigate the spatial patterns of soil HMs and identify their main sources in a regional scale.

Materials and methods

A total of 110 topsoil samples were collected from Tai’an City, China. Cd, Cr, Cu, Hg, Ni, Pb, and Zn concentrations in each soil sample were determined. Geostatistics, geographic information system (GIS), and positive matrix factorization (PMF) were used to explore the spatial distribution of seven soil HMs and to reveal the main sources of soil HMs in Tai’an City, respectively.

Results and discussion

Soil Cd, Cr, Pb, and Zn generally showed slight pollution levels in the study area. However, soil Hg and Cu contents reached moderate to heavy pollution levels in some areas. Soil Hg content increased from north to south across the city, and the highest Hg concentration was detected in Ningyang County. Soil Cd, Cu, and Zn distributions exhibited a similar pattern, and their contents increased from west to east; the highest Cd, Cu, and Zn concentrations were found in Xintai County. The highest soil Ni concentration was obtained in the northeast of Feicheng and Xintai counties. PMF analysis revealed the following four potential sources of agricultural soil HMs in Tai’an City: industrial and mining activities, agricultural activities, residential living activities, and business activities. Soil Hg mainly originated from residential living activities, which accounted for 75.3% of the total source. The main sources of soil Ni were residential living activities, agricultural activities, and industrial and mining activities, which account for 38.2, 27.50, and 25.1% of the total source, respectively. Soil Cu was mainly produced by agricultural activities (36.6%), followed by residential living activities (29.8%) and industrial and mining activities (25.8%).

Conclusions

PMF combined with GIS could be effectively applied to determine the main sources of HMs in agricultural soils in a regional scale.

     

Distribution of Trace Metals in Channel Sediment: a Case Study in South Atlantic Coast of Spain

Recently, Sancti Petri channel on the southwestern (SW) part of Iberian Peninsula has been experiencing urban, industrial, and vehicular expansion. Until recently, there have been only few published reports documenting the pattern of metal accumulation in this estuarine sediment. In the present study, trace metals such as Cu, Zn, Ni, Mn, Pb, Co, Cd, As, and Hg concentrations were analyzed from 69 sediment samples collected from 23 sampling sites of the Santi Petri channel. The magnitude of trace metal accumulation found as the following trend: Mn > Zn > Cu > Pb > Ni > Co > As > Cd > Hg. Spatial distribution pattern demonstrated overall decreasing trend of trace metal from Cadiz Bay mouth to the open ocean mouth, clearly correlative to the presence of anthropogenic inputs. Results of the principle component analysis (PCA) revealed that sediment metal chemistry of Sancti Petri channel is mainly regulated by the concentrations of Pb, Cu, Zn, and Ni; possible sources of those were from vehicular-related emissions. Pollution load index (PLI) and geo-accumulation index (I _geo ) indicated overall low values. The study will stimulate improvement of our understanding regarding the pattern of accumulation of metals in the coastal sediments, and the recorded values of metals in the present study can be used as suitable reference for future studies.     

Inorganic and organic pollution in agricultural soil from an emerging e-waste recycling town in Taizhou area, China

Purpose

The emerging recycling of electronic and electric waste (e-waste) is causing critical levels of soil pollution in those relatively poor towns surrounding the central cities, which have been involved in recycling activities for quite some time. Agricultural soil is of great importance due to its direct impact on food and human health. The objective of this study was to provide a systematic investigation of the contamination in agricultural soil for a range of inorganic compounds (Cr, Cd, Pb, Zn, Cu, and Ni) and organic compounds (PAHs and PCBs) in town A, an emerging e-waste recycling town in China.

Materials and methods

A total of 20 agricultural soil samples were collected from three sampling locations throughout town A. Levels of inorganic compounds (Cr, Cd, Pb, Zn, Cu, and Ni) and organic compounds (PAHs and PCBs) were determined by AAS, GC/MS, and GC/electron capture detector, respectively. Data was processed with SPSS 13 and Arcview 3.3 GIS software.

Results and discussion

The findings demonstrate that agricultural soil was contaminated to various extents by inorganic and/or organic pollutants. Comparison among the three sampling areas indicated that the soil was highly contaminated in the agricultural area near e-waste recycling workshops. Moreover, the contaminants (Cu, Pb, PAHs, and PCBs) may be connected through a common source as found in the Pearson correlations and cluster analysis.

Conclusions

There exists a heightened sense of awareness concerning the hazardous implications of current emerging e-waste recycling issues in the agricultural soil of those areas close to the central city in Taizhou.     

Heavy metal and PCB spatial distribution pattern in sediments within an urban catchment—contribution of historical pollution sources

Purpose

This work analyzes polychlorinated biphenyl (PCB) and heavy metal contamination in fluvial sediments and soils in an urban catchment, according to the geo-accumulation index and to soil and sediment quality guidelines. The catchment is located in Coimbra, Portugal, being affected by frequent flooding, and its main stream is a tributary to one of the major rivers in Portugal (Mondego). Given the presence of industrial activities over time, some inputs of pollutants are expected, but so far, the legacy of historic pollution in this catchment has not yet been investigated.

Materials and methods

Twenty-five samples were collected from nine sampling sites at the depths of 0–20, 20–40 and 40–60 cm (to provide a historic perspective) along longitudinal profiles (streamlines) and in soils downstream of pollution sources. These samples were analyzed for six heavy metals (Cu, Cr, Pb, Cd, Zn, Ni), organic carbon, pH and ten PCBs (IUPAC numbers 28, 30, 52, 101, 138, 153, 166, 180, 204, 209).

Results and discussion

Total PCB concentrations ranged 0.47–5.3 ng g^?1 dry weight (dw), and levels increase from the bottom to the top layers, suggesting an increased input over the last 100 years. PCB congener distribution shows the dominance of hexachlorobiphenyls, especially PCB138, suggesting the existence of local sources. PCB levels did not exceed sediment quality levels, placing sediments/soil under class 1 (not contaminated) or class 2 (trace contamination) with respect to PCB. All six metals exceeded the lowest effect level for sediment quality criteria, and three (Cd, Pb and Zn) largely exceeded the clean levels for dredged materials, placing sediments in class 5 (heavily contaminated). Sampling site S1 presented the highest concentrations of Zn, Pb and Cd, and historic vehicle traffic was identified as the most likely source, given the vertical and horizontal profiles.

Conclusions

High levels of Pb, Cd and Zn were found in fluvial sediments at some locations of the Loreto catchment, likely from historic traffic sources. This urban area is frequently affected by flooding events and is currently being subject to urban redevelopment. During these events/actions, historic pollutants in the sediments might surface and be redistributed, impacting the downstream ecosystem of the major Mondego River or increasing the risk of exposure of the urban population.

     

Influence of plant species and phosphorus amendments on metal speciation and bioavailability in a smelter impacted soil: a case study of food-chain contamination

Purpose

The present research aimed to assess the influence of two phosphorous (P) amendments on metal speciation in rhizosphere soil and the soil–plant transfer of metals.

Materials and methods

Complementary experiments were performed: field experiments on a contaminated cultivated soil and laboratory experiments on an uncultivated contaminated soil to highlight the mechanisms involved in metal-phosphorous interactions. In laboratory experiment, P amendments were added at 120 mg P/kg of soluble KH₂PO₄ amendment and 9,000 mg P/kg of solid Ca₅(PO₄)₃OH amendment.

Results and discussion

Field-culture results showed the possible food-chain contamination due to Pb, Cd, Cu, and Zn phytoaccumulation by pea and mustard plants from a cultivated agricultural soil. Moreover, P-metal complexes were observed by microscopy in the rhizosphere soil. In laboratory experiments, the application of P amendments significantly increased Pb and Zn level in rhizosphere soil compared to control. Phosphate amendments significantly increased metal-P fraction and decreased “oxides” and “organic matter” fractions of Pb and Zn. Soluble-P amendment was more effective than solid P amendment in changing Pb and Zn speciation. The changes in metal speciation are higher in the rhizosphere soil of pea than tomato. Application of P amendments increased Pb and Zn TF root/soil but decreased TF shoot/root.

Conclusions

The effectiveness of in situ metal immobilization technique varies with the type and quantity of applied P amendment as well as plant and metal type.     

Soil Contamination by Toxic Metals Near an Antarctic Refuge in Robert Island,Maritime Antarctica: A Monitoring Strategy

The anthropogenic effects of Antarctic refuge buildings and research stations on the surrounding soils are scarcely investigated, especially when the structures are small-sized, and sporadically used or visited. The Coppermine Peninsula (Robert Island, South Shetland Islands archipelago) possesses one of the richest flora in Antarctica, being classified as an Antarctic Specially Protected Area (ASPA). There, a small refuge (Luis Risopatrón) has been seasonally occupied for scientific purposes since 1957, although no studies on the anthropic disturbances in the surroundings soils are reported. The aim of this study was the determination of the potentially toxic metals (Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn) mass fractions in surface soils (n?=?40) collected at the surroundings of the Luis Risopatrón refuge. Enrichment factors (EF) and geoaccumulation index (I _geo) were also calculated, using Zr as the reference element, in order to evaluate the anthropogenic impacts of these small buildings in the studied area. The main contaminants were Pb and Zn, which presented EF and I _geo values ranging from 1.0 to 18.3 and from ?1.8 to 3.5. The mass fractions of these elements determined after an aqua regia extraction varied from 5.4 to 102 mg kg^?1 Pb and from 43 to 210 mg kg^?1 Zn. These results highlight that a small refuge can show environmental disturbance from low to moderate, with few hotspots with heavily contaminated soils. Environmental monitoring strategy for similar refuges anywhere in Antarctica is recommended.     

The transfer of heavy metals to barley plants from soils amended with sewage sludge with different heavy metal burdens

Purpose

Our main aim objective was to evaluate the transfer of Cd, Cr, Cu, Ni, Pb and Zn to barley (Hordeum vulgare) grown in various soils previously amended with two sewage sludges containing different concentrations of heavy metals. This allowed us to examine the transfer of heavv metals to barley roots and shoots and the occurrence of restriction mechanisms as function of soil type and for different heavy metal concentration scenarios.

Material and methods

A greenhouse experiment was performed to evaluate the transfer of heavy metals to barley grown in 36 agricultural soils from different parts of Spain previously amended with a single dose (equivalent to 50 t dry weight ha^?1) of two sewage sludges with contrasting levels of heavy metals (common and spiked sludge: CS and SS).

Results and discussion

In soils amended with CS, heavy metals were transferred to roots in the order (mean values of the bio-concentration ratio in roots, BCF_Roots, in brackets): Cu (2.4)?~?Ni (2.3)?>?Cd (2.1)?>?Zn (1.8)?>?Cr (0.7)?~?Pb (0.6); similar values were found for the soils amended with SS. The mean values of the soil-to-shoot ratio were: Cd (0.44)?~?Zn (0.39)?~?Cu (0.39)?>?Cr (0.20)?>?Ni (0.09)?>?Pb (0.01) for CS-amended soils; Zn (0.24)?>?Cu (0.15)?~?Cd (0.14)?>?Ni (0.05)?~?Cr (0.03)?>?Pb (0.006) for SS-amended soils. Heavy metals were transferred from roots to shoots in the following order (mean values of the ratio concentration of heavy metals in shoots to roots in brackets): Cr (0.33)?>?Zn (0.24)?~?Cd (0.22)?>?Cu (0.19)?>?Ni (0.04)?>?Pb (0.02) for CS-amended soils; Zn (0.14)?>?Cd (0.09)?~?Cu (0.08)?>?Cr (0.05)?>?Ni (0.02)?~?Pb (0.010) for SS-amended soils.

Conclusions

Soils weakly restricted the mobility of heavy metals to roots, plant physiology restricted the transfer of heavy metals from roots to shoots, observing further restriction at high heavy metal loadings, and the transfer of Cd, Cu and Zn from soils to shoots was greater than for Cr, Ni and Pb. Stepwise multiple linear regressions revealed that soils with high sand content allowed greater soil-plant transfer of Cr, Cu, Pb and Zn. For Cd and Ni, soils with low pH and soil organic C, respectively, posed the highest risk.     

Cadmium contamination of sediments in the water reservoirs in Silesian Upland (southern Poland)

Purpose

Cadmium (Cd) is considered a toxic element and its concentrations are relevant to human health and the environment. Therefore, the purpose of the study was to determine the extent to which the bottom sediments of water bodies (artificial lakes and ponds) in the Silesian Upland in southern Poland are contaminated with Cd; an attempt was also made to determine the factors that condition spatial differences in the concentration of this element between individual water bodies in the region.

Materials and methods

Measurements of the Cd content in bottom sediments were carried out in 35 water bodies in southern Poland in 2011 and 2012. Depending on the surface area and morphometric characteristics, from two to nine samples representative in terms of sediment thickness were collected in each water body. Cadmium concentrations were determined for 92 0.25 g aliquots using the TD-ICP method.

Results and discussion

Cadmium content in all samples (0.7–580.0 mg kg^?1) was higher than the natural range of concentrations for this element in the Earth’s crust (0.1–0.3 mg kg^?1) and the geochemical background for Poland (0.5 mg kg^?1) and, with a few exceptions, was also higher than the preindustrial concentration (1.0 mg kg^?1) and the regional geochemical background (2.5 mg kg^?1). Adopting natural Cd concentrations in the Earth’s crust (0.1–0.3 mg kg^?1) as the baseline for the geoaccumulation index (I_geo), the sediments examined can be classified as extremely and heavily contaminated (and moderately contaminated in a small number of cases). The assessment of sediment quality based on I_geo, with the regional geochemical background (2.5 mg kg^?1) adopted as the baseline, results in non-contaminated and moderately contaminated sediments being dominant with a far smaller number of heavily and extremely contaminated ones.

Conclusions

In the case of several water bodies, Cd concentrations were at record levels that have not been found anywhere else in the world. On the basis of the I_geo, sediments of varying quality were found—from virtually uncontaminated to extremely contaminated. The I_geo index as an indicator of the quality of bottom sediments is a measure that requires careful interpretation, especially when different concentration levels regarded as natural are used for determining its value.

     

Transfer of Cd, Pb, and Zn to water spinach from a polluted soil amended with lime and organic materials

Purpose

The transfer of heavy metals from soil to crops comprises several steps, including soil-to-root and subsequent root-to-shoot tranfer. The purpose of this study was to investigate the different steps of soil-to-crop transfer of Cd, Pb, and Zn.

Materials and methods

This study was carried out with a greenhouse pot experiment using a soil polluted with Cd, Pb, and Zn which was amended with rice straw, pig manure, sheep dung, or peat, with and without lime. Water spinach (Ipomoea aquatica) was used as the test crop and was grown after a season of rice cultivation.

Results and discussion

The results showed that all the amendments promoted the root-to-shoot transfer of Cd, Pb, and Zn. The soil-to-root transfer factors (TFs) of Pb and Zn tended to increase with increasing available Pb and Zn in the soils, while no clear relationship between the TF of Cd and available soil Cd was observed. The root-to-shoot TF of Cd, Pb, and Zn tended to decrease with increasing available amounts in the soils and were negatively correlated with the concentrations of the metals in the roots (r _Cd?=?0.820, r _Pb?=?0.789, r _Zn?=?0.769).

Conclusions

The soil-to-root transfer of Cd, Pb, and Zn was significantly different from the root-to-shoot transfer. The soil-to-root transfer was mainly influenced by the amount of available metal in soil, whereas the root-to-shoot transfer was mainly controlled by the concentrations of the metals in the root.     

Monitoring of plant and soil pollution based on ionic impulsion

Total pollution indexes for measuring heavy metal contamination of industrialized areas may be quickly estimated from selected metal partial indexes for soil (M-SPI) or plants (M-PPI). Partial pollution indexes for plants (or soils) are calculated by the formula M-PPI (or M-SPI) = 100 (I ? I _unp)/(I _tox ?I _unp), where I = c _i ^1/ni is the ionic impulsion of the selected metal M, with oxidation number n _i, for its actual plant (or soil) concentration c _i,and I _unp and I _tox, the ionic impulsions for unpolluted and toxid levels of the M in plants (or soils). The total pollution indexes were proposed by analogous formulae containing the sums of contributions of metals accumulated in roots (Pb, Cd, Co, Cr, Ni, Cu, Zn and also Fe for plants), without participation of macroconstituents (K, Mg, Ca, Na, and also Mn), accumulated in plant tops. Partial pollution indexes may also serve to show (i) deficiency or toxicity levels of plants (or soils) and (ii) associations between pollutants, easily detected by a numerical taxonomy's dendrogram. Using correlation coefficient techniques for the Bilbao (Spain) model zone, the total soil pollution index, SPI, may be calculated from Zn-SPI, Pb-SPI, Cu-SPI or Cu-PPI. The total plant pollution index, PPI, is similarly related to Fe-PPI or Zn-PPI, though some distortion is evident when the sampling point is close to specific industrial factories. The best estimation (without distortion) for monitoring total plant pollution index is based on the sum of contributions of essential elements (Fe, Cu, and Zn). This fact suggests the existence of defense mechanisms of plants for balancing both the uptake of toxic metals and deficiencies of essential constituents. Finally total pollution indexes may be used for the estimation of the number of pollutants with toxic levels in plants or soils.     

Spatial patterns and temporal changes of heavy metal distributions in river sediments in a region with multiple pollution sources

Purpose

The main purpose of this study was to evaluate temporal and regional variability of contamination by heavy metals (HMs) in river sediments using their enrichment factors (EFs) and benchmarking according to sediment quality guidelines (SQGs). The Zlin region in the Czech Republic (Morava and Drevnice River basins) represents a model area where several regionally specific ecological risk assessment studies have recently been conducted with a focus on organic pollution, eco-toxicity, geological, and geochemical characteristics.

Materials and methods

Four consecutive sediment sampling campaigns were undertaken in spring and autumn 2005–2006. Aqua-regia leachable content of Cd, Co, Cr, Cu, Ni, Pb, Sb, V, and Zn in surface sediments from 14 sites was analyzed using ICP-MS, and Hg content was analyzed using AMA-254 analyzer. EFs were calculated to identify the human impact on pollution in the area. Comparisons to SGQs were conducted to identify the areas and HMs of greatest risk.

Results and discussion

Calculation of EFs contributed to the effective clustering of HMs. Median EFs of Co, Ni, and V ranged from 0.9 to 1.4 at all sites indicating concentrations very close to natural geological background levels. There was greater enrichment at locally polluted sites, the highest in the cases of Cd, Sb, Hg, and Cr. Widespread influence of diffuse HM sources (traffic, agriculture, and urban wastes) was apparent from elevated concentrations of Pb, Cu, and Zn at all sites. EF values also helped to identify the greatest temporal changes and shifts in HMs contamination between adjacent sites caused by 50-year recurrence interval floods in early spring 2006. The impact was most apparent in downstream sites; namely directly below the confluence of the two major rivers.

Conclusions

The overall contamination of HMs in the region was classified as low-to-moderate with significantly contaminated sub-areas. The study showed relatively stable spatial distributions of HMs, indicating potential sources of pollution. Cu was identified as the HM of greatest risk. The study emphasizes the necessity of considering both environmental circumstances and background HM occurrence to prevent misinterpretation of the pollution situation. The use of EFs which include grain size proxy normalization and HM background levels, along with the comparison of the detected concentrations to SQGs, proved an efficient way to identify hazardous contamination from anthropogenic sources.     

抚仙湖重金属污染强度、历史及来源的沉积记录

This study focused on the concentration change of heavy metals of sediment cores in heavily polluted north area and less polluted middle area of Fuxian Lake in Southwest China.On the basis of the analysis of Cu,Ni,Ti,V,Pb,Cd,and Zn concentration-depth profiles,the pollution history of heavy metals was studied using ¹³⁷cesium (¹³⁷Cs) dating.The sources of heavy metals were distinguished by normalization of their profiles to aluminum and analysis of heavy metal concentrations of potential source materials.Geoaccumulation index (I_geo) was used to quantify their contamination intensity.The results showed that all the heavy metals found in the Fuxian Lake sediments originated naturally before 1980s.Cu,Ni,Ti,and V were still mainly natural in the north lake after 1980s,Cu,Ni,Ti,V,and Pb were mainly natural in the middle lake at all time,but the concentrations of Pb and Zn in the north lake were influenced by industrial wastes from the phosphorus fertilizer factory and cement plants.In all the lake,the contaminations of Cd and Zn were the results of agricultural cultivation using a large amount of fertilizers and the atmospheric fallouts of dusts from cement plants.At present,the geoaccumulation indices showed that the Fuxian Lake sediments were moderately to strongly polluted by Cd in the middle lake,and unpolluted to moderately polluted by Pb and Zn and strongly polluted by Cd in the north lake.Moreover,the pollution intensities of Cd,Zn,and Pb have been increased since 1980s.     

Anthropogenic environmental impact in the Mediterranean coastal area of Koper/Capodistria,Slovenia

Purpose

Heavy metal content in soils could be a consequence of geogenic and different anthropogenic sources. In ancient times, soils in the Mediterranean region were affected by agriculture and viticulture, whereas more recently, industry and traffic might contribute more to their pollution. The aim of the study is to determine the extent of multisource heavy metal pollution in soils within the Koper area.

Materials and methods

Along the northern Adriatic Sea coast, around the port city of Koper/Capodistria, 24 topsoil samples were collected; sets of six samples representing four possible pollution sources: intensive agriculture, viticulture, port activities and industry. The parent material of the soil is mainly derived from the Eocene flysch weathered marls and calcarenites and the soil types are eutric. The chemical composition of the samples was determined by ICP-ES for oxides and several minor elements and by ICP-MS for heavy metals. The mineral composition of the selected samples was checked using X-ray powder diffraction. Different statistical analyses were performed on the normally distributed data.

Results and discussion

The mean concentrations of all samples are: Cr 215 mg kg^?1, Ni 81 mg kg^?1, Zn 67 mg kg^?1, Cu 44 mg kg^?1 and Pb and Co 18 mg kg^?1. The ANOVA showed significant differences only in CaO, C/TOT, P₂O₅, Co and Pb between those locations within reach of the different contamination sources. The observed average values of heavy metals are well below Slovenia’s Directive limit for Cu, Pb and Zn, close to but not above it for Co and above the action value for Cr and Ni. According to Igeo, soils from all the sampling locations are uncontaminated with Co, Ni and Pb, and uncontaminated to moderately contaminated with Cu and Zn at one port location, and with Cr at all locations.

Conclusions

The very high Cr and Ni levels could still be geogenic because soils developed on Eocene flysch rocks are enriched in both metals. Cr and Ni are not correlated because of their different levels of sorption and retention in carbonate soils. Cr was retained and concentrated in the sand fraction but Ni has been mobilised in solution. The only serious threat to the environment seems to be an illegal waste dumping area near the port.