Heavy metal behaviour during the activated sludge process I. Extent of soluble and insoluble metal removal

The extent of removal of Ag, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Tl and Zn and their distribution between the soluble and insoluble phases in the influent, and effluent of the activated sludge process has been studied using a pilot-scale plant operated at sludge ages of 3, 6, 9 and 12 days. Molybdenum, Tl, Co, Mn and Ni were >50% soluble in the influent settled sewage. The mean removals of the former two metals were <3% and the latter three were 35 and 50%. Silver, Bi, Cd, Cr, Cu, Pb and Zn were all <35% soluble in the influent and had substantial removals of >75%. Solubilities were greater in the effluent than the influent with the exception of Mn. The observed overall removals of Ag, Bi, Co, Ni, Pb, Tl and Zn were almost entirely due to insoluble metal removal; Cd, Cr and Cu removals had a significant contribution from soluble metal removal. Overall Mn removal appeared to be solely due to soluble metal removal.     

Subcellular and body distributions of 17 trace elements in the variegated scallop Chlamys varia from the French coast of the Bay of Biscay

Seventeen elements were analysed in the organs and tissues of the variegated scallop Chlamys varia, from the Atlantic coast of France. Concentration levels were determined in scallops of different sizes sampled in contaminated (La Rochelle Bay) and clean (Re Island) sites. Greater concentrations of Ag, Al, Ce, Cr, La, Mo, Nd, Ti, and V were found in the digestive gland while As, Cd, Co, Cu, Mn, Ni, Pb, and Zn were the highest in the kidneys. In the digestive gland, most of the metals were found in the insoluble fraction while As, Co, Cd, Mo, Ni, and V appeared to be mostly bound to soluble compounds. Among tissues, the adductor muscle always displayed the lowest trace element concentrations. According to size, Ag and Cd showed significantly higher concentrations in larger individuals, while Co and Zn were higher in the smallest ones. According to the sampling area, most of the metals, Ag, Al, Ce, Co, Cu, La, Mn, Nd, Pb, and Zn, showed significantly higher concentrations in La Rochelle Bay compared to the Re Island, reflecting differing inputs from industrial, domestic and harbour activities. However, Cr, Mo, Ni, Ti, and V concentrations did not display significant differences between sites and As and Cd were significantly higher at the Re Island. This study highlighted the ability of the variegated scallop C. varia to concentrate numerous trace elements to high levels, even those reported as poorly bioavailable for marine biota, such as rare earth elements.     

Annual atmospheric deposition of 16 elements in eight catchments of the central Barents region

Snowpack and rainwater samples were used to calculate total yearly deposition rates for Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mo, Ni, Pb, S, Sb, Sr and V in eight catchments located within the Barents region, in Finland, Norway and Russia. Water-soluble (<0.45 μm) deposition and particulate (>0.45 μm) deposition were determined separately on snowpack samples representative of winter 1993/1994. Filtered rainwater sampled during the summer months of 1994 was used to obtain monthly water-soluble deposition data. The snow data were used to calculate the characteristic parameters of dispersion of the pollutants, which are constant for any given industrial source. To obtain these parameters, the element ratio of water-soluble to particulate deposition was expressed as a function of distance from pollution source. This function can then be used to calculate total (water-soluble+particulate) summer deposition data from the water-soluble deposition data collected. Yearly deposition estimates (in kg/km²) obtained for the area range from 0.05 to 0.4 for Cd, 0.02–60 for Co, 0.14–5.2 for Cr, 0.5–494 for Cu, 0.2–845 for Ni and 125–1500 for S, depending on location (remote vs. industrial).     

Trace element concentrations in blood of harbor seals (Phoca vitulina) from the Wadden Sea

Concentrations of 23 elements (Be, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Pd, Cd, Sn, Pt, Pb) were evaluated in whole blood samples of live harbor seals (Phoca vitulina) from two different locations in the Wadden Sea, the Lorenzenplate in Germany, and the Danish island R?m?. Elemental blood levels were compared to data from literature of seals, other marine mammals and humans. While homeostatically controlled elements showed no differences, concentrations of As, Cr, Mn, Mo, Se, and V were higher than human levels. Furthermore, animals from both locations showed significant geographical differences in whole blood concentrations of Al, Mn, Cu, and Pt. These findings could be explained by differences in feeding areas. The element pattern was not affected by gender. In conclusion, these findings indicate an impact of the environment on biochemical blood parameters of the harbor seals. The significant differences of elements in blood samples of two groups of seals, which were associated with geographical variations of prey support the use of element pattern in blood as tool for investigation of environmental impact on seals.     

Concentrations of selected metals in honey consumed in Nigeria

The concentration of metals, cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr), copper (Cu), cobalt (Co), iron (Fe), manganese (Mn), and zinc (Zn) was measured in selected samples of honey in Nigeria with a view to providing information on the regional concentration profile of metals in these honeys. The honey samples were digested with a mixture of acids and analysed for metal concentrations using atomic absorption spectrophotometry. The concentrations of metals (mg kg^?1) in these honeys ranged from < 0.3 for Cd,<0.50–39.75 for Pb,<0.25–6.98 for Ni,<0.25–55.25 for Cr,<0.25–71.25 for Cu,<0.25–3.50 for Co,<5.0–163.15 for Fe,<11.0–31.75 for Mn and 1.0–31.0 for Zn. The concentrations of metals were relatively high but lower than their respective permissible limits in food except for Pb and Cu in some samples. The regional distribution patterns of metals indicated that honey samples from the Niger Delta region of Nigeria had higher mean concentrations of Ni, Cr, Co, Fe and Zn than honey samples from other regions. The honey samples from the northern region had higher mean concentrations of Pb and Cu.     

Variations in heavy metal concentrations in the moss species Abietinella abietina (Hedw.) Fleisch. according to sampling time,within site variability and increase in biomass

Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mo, Ni, Pb, V and Zn were analysed in the moss Abietinella abietina (Hedw.) Fleisch. to estimate atmospheric heavy metal depositions. Samples were taken at five comparable sites within a radius of 25 m four times during the year 2000 (July 3rd, August 3rd, September 7th, October 3rd). The samples were taken by means of a PVC-tube (r=10 cm) and could therefore be related to aboveground growth and aerial deposition. The investigation showed significant differences between the various sampling times for concentrations of all heavy metals in total but not between concentrations of a single metal. For Cu, Hg, Mo, Pb and Zn temporal variation (=variation between the four times of sampling) was larger than spatial variation (=variation of concentrations between sub-samples at a single sampling time). Growth rates of the mosses differed significantly between sampling times, which reflects the low precipitation at the beginning of the season. Biomass increase, dust and precipitation influenced the metal concentrations. The calculation of deposition rates, which takes growth rates into account, showed significant differences between the various sampling times for Al, Cd, Cr, Cu and Ni, which is controversial to the results obtained from concentrations of these elements. Additionally, the calculation of atmospheric deposition rates showed a constant increase of metal depositions throughout the investigated period, which can not be seen by considering the concentrations only.     

Effects of acid mine drainage on groundwater quality: a case study from an open-pit copper mine in eastern Turkey

This study was undertaken to determine the variation in groundwater quality of an open-pit copper mine in Maden (eastern Turkey) which has been in operation since 2000 BC, and with modern methods since 1939. Physical and chemical parameters (including pH, temperature, electrical conductivity, concentrations of Na, K, Ca, Mg, Cl, HCO₃, SO₄, NO₃, Fe, Co, Cr, Mn, Ni, Cu, Zn, Al, Cd, and Pb) of the groundwater and spring water samples from the study area were measured on a seasonal basis between October 2009 and July 2010. The groundwater quality was hydrochemically assessed in order to determine its suitability for human consumption and agricultural use. The measured and analyzed parameters in all the water samples were below the maximum admissible concentrations set out in international and national standards, guidelines, directives, and regulations for human consumption and for agricultural purposes. In addition, the results of previous studies on the possible effects of the mine site on soil, stream sediment, plants, and surface water in the same area are discussed.     

Trace metal partitioning in marine sediments and sludges deposited off the coast of Barcelona (Spain)

As part of a study on the environmental impact of the sludges discharged on the littoral platform in front of Barcelona (Spain), marine sediment samples were analysed. Major components were determined and the Tessier sequential extraction procedure was applied to study Cd, Cu, Cr, Ni, Pb and Zn distribution in eleven samples taken at nine sampling sites. From the data it can be inferred that in this type of sediment with high carbonate content, Cd is the most easily extractable metal, followed by Cr, Pb and Zn, and that Cu and Ni are the most retained. The anthropogenic contribution is also evaluated from the total metal contents using the metal content of a relatively non-polluted sediment sample taken from the same area as a baseline.     

Concentrations of heavy metals and plant nutrients in water, sediments and aquatic macrophytes of anthropogenic lakes (former open cut brown coal mines) differing in stage of acidification.

Concentration of heavy metals (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn) as well as macronutrients (N, P, K, Ca, Mg, S) were measured in water, bottom sediments and plants from anthropogenic lakes in West Poland. The collected plants were: Phragmites australis, Potamogeton natans, Iris pseudoacorus, Juncus effusus, Drepanocladus aduncus, Juncus bulbosus, Phalaris arundinacea, Carex remota and Calamagrostis epigeios. Two reference lakes were sampled for Nymphaea alba, Phragmites australis, Schoenoplectus lacustris, Typha angustifolia and Polygonum hydropiper. These plants contained elevated levels of Cd, Co, Cr, Cu and Mn, and part of the plants contained in addition elevated levels of Mn, Fe, Pb, Ni and Zn. Analyses of water indicated pollution with sulfates, Cd, Co, Ni. Zn, Pb and Cu, and bottom sediments indicated that some of the examined lakes were polluted with Cd, Co and Cr. Strong positive correlations were found between concentrations of Co in water and in plants and between Zn in sediments and plants, indicating the potential of plants for pollution monitoring for this metal. Heavy metal accumulation seemed to be directly associated with the exclusion of Ca and Mg.     

承德黑山钒钛磁铁矿矿集区土壤重金属空间结构特征与生态风险评价

矿区土壤重金属来源、空间分布特征对矿山周围的生态环境脆弱区土壤环境保护、修复以及生态风险评价具有重要意义。本文以承德市隆化县韩麻营镇黑山钒钛磁铁矿所在小流域为研究区,利用地累积指数法、内梅罗污染指数法验证矿区周围土壤重金属污染程度,利用潜在生态危害指数法对土壤重金属的生态环境风险做了全面评价,利用变异函数、相关性分析、金属元素主成分和聚类分析等方法明确了研究区重金属来源及空间分布特征。研究结果表明:研究区土壤中重金属元素Mn、Ti、V、Zn、Co、Cu、Mo、Cd和SOM的平均含量均高于河北省背景值;重金属元素As、Cr、Ni、Sb、Pb的平均含量均略低于河北省背景值;土壤重金属元素的空间分布十分均匀。研究区大量土壤重金属元素为轻度污染,少量为中度污染,只在极少量的局部地区土壤重金属元素Ti、Cu、Co、Hg、Cr显示出重污染特性。研究区整体处于较清洁水平,并且研究区土壤重金属元素高值点主要分布在矿区周围和人类活动区域,钒钛磁铁矿矿区及其伴生矿物和人类生产活动对重金属元素含量分布有较大影响。     

Concentrations and leachability of chemical elements in estuarine sulfur-rich sediments, W. Finland

Concentrations, distributions and mobility of chemical elements were investigated in reduced sulfur-rich estuarine sediments located in western Finland. The main objective was to determine the possible extent of metal leaching when dredged masses of these sulfur-rich sediments are dumped on the land and thus exposed to air. When dredged, the reduced sulfur in the sediments oxidises resulting in a lowering of pH, which in turn is expected to leach metals. The study area is an artificial lake claimed from the Botnian sea in 1962. In this lake, several mass-kills of fish have occurred, believed partly to be due to dredging. Two sediment samples (0-50 and 50-100 cm) were taken from 39 sampling points in the lake. These samples were leached in aqua regia (2:2:2 HNO3/HCl/H2O1) and analysed for Fe, Al, Mg, Ca, K, P, Na, Mn, Zn, Ba, V, Sr, Cr, Ni, Cu, Co, As, Pb, B, Mo and Cd with ICP-AES. Sulfur and organic carbon were analysed with Leco. In a controlled laboratory experiment, the sediments were allowed to oxidise for 1 year while moisturised with deionised water every month. The pH and conductivity were determined in the beginning of the experiment (reduced state) and in the end (oxidised state). In the supernatants in the oxidised states the amount of leached metals (Na, Al, Mn, Zn, Sr, Co, Ni, Cu, Cd, Cr, Pb, U, Li, Rb and As) were determined with ICP-MS. The sediments were found to contain low levels of toxic metals but, as expected, high concentrations of sulfur. In the experiment, pH was lowered (down to 3.0) and the conductivity increased in all samples due to oxidation and release of metal ions. The extent of leaching varied between 0.03% for As and 12.3% for Na. Critical pH values, at which high amounts of metals begin to leach, were obtained graphically. These values varied between 4.8 (Ni) and 3.3 (Cr). Not all elements were controlled by pH, e.g. Mn correlated well with its aqua regia leachable concentration. In a planned dredging operation in the area some 23,300 t (10,500 m3) (dry wt.) of sediments will be dredged. The amounts of metals likely to be leached, according to the results from this study, are as follows (kg): Al (1710), Mn (1230), Zn (59), Sr (39), Co (13), Ni (12), Cu (2) and less than 1 kg of Cd-Cr-As-Pb.     

Heavy metal and trace element distributions in groundwater in natural slopes and highly urbanized spaces in Mid-Levels area, Hong Kong

The lower slope of the Mid-Levels area, Hong Kong, is one the most heavily urbanized coastal areas in the world. A comprehensive groundwater heavy metal and trace element study was conducted in the Mid-Levels area aiming to investigate the impacts of urbanization on the aqueous distributions of these chemicals. Groundwater samples were collected in the upper natural slopes and the lower highly urbanized spaces in the area in different seasons, and analyzed for heavy metal and trace element contents. Compared to the results from natural slopes, groundwater samples in the developed spaces did not exhibit significant elevated levels in Zn, Cr, Cu, Cd, Pb and Fe, which are commonly found in stormwater. On the other hand, the samples were found to have elevated contents in Mn, V, Co and Mo, minor stormwater-related heavy metals, suggesting that stormwater drains may be leaking to some extent. However, the results suggested that the vadose zone could remove many of the heavy metals, protecting groundwater from being contaminated seriously. Statistical analysis suggested that a certain amount of Mn and Co was likely to be re-mobilized from natural soils due to the changes in local redox conditions, while Mn, V, Co and Mo may also be derived from steel corrosion as a result of prolonged submergence. Besides, the average B concentration in the developed spaces was about eight times higher than that in the natural slopes, indicating the presence of sewage. The mean Se concentration in the developed spaces was about 100 times higher than that in the natural slopes. About 40% of samples in the developed spaces contained Se level higher than the drinking water guideline value proposed by the World Health Organization. Se was found to be positively correlated with B and SO4(2-) (R = 0.534 and 0.631, respectively), suggesting that Se may also be related to leakage from sewage pipes. Part of the Sr may come from leakage of flushing water and/or sewage as Sr was strongly correlated with Cl- (R = 0.929). According to the measured results, deep groundwater samples collected from piezometers (> 10 m in depth) in the urbanized spaces appeared to be virtually free from any anthropogenic contaminations. This study may shed important light on the identification and evaluation of leakage from service pipes in a particular area based on aqueous distributions of heavy metals and trace elements. Moreover, the above findings may be instructional for other coastal cities with a similar level of urban development to understand the potential threats to their groundwater resources.     

Movement of heavy metals into a shallow aquifer by leakage from sewage oxidation ponds

The concentrations of Mn, Ni, Cu, Cd and Cr were measured in a shallow perched groundwater aquifer which underlies the Dan Region Sewage Reclamation Project (Israel). The contribution of effluents to the groundwaters has been evaluated on the basis of chloride concentration. Groundwater which are estimated to contain more than 60% effluents showed a hundred-fold decrease in Cu and Mn at a distance of 650 m away from the ponds, as compared with the near ponds samples. Ni and Cd showed only a small decrease in concentration over a distance of 150 m, and then stayed constant. The concentrations of Cu and particularly of Mn in the groundwaters near the oxidation ponds is equivalent to or greater than in the ponds themselves. It is suggested that Cu and Mn are mobilized from the precipitated sludge into the interstitial waters. They percolate into the groundwater near the ponds and then are precipitated by increasing aeration during the movement of the water away from the pond area. Cd and Ni form stable soluble organic chelates which are only slightly removed by interaction with the sandy soil of the aquifer.     

Application of high Cu compost to Swiss chard and basil

A greenhouse container experiment was conducted to evaluate the effect of high Cu compost on basil and Swiss chard productivity, and the accumulation of As, Ca, Fe, Hg, K, Mg, Na, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, S and Se in growth medium and plant tissue. The Cu content of the compost was over 1200 mg/kg, much higher than Canadian standards for type B compost quality. The treatments consisted of control soil (0% compost), and 20, 40 and 60% (by volume) of high Cu compost added to soil. All compost application treatments (20, 40 and 60%) resulted in increased dry matter yields in Swiss chard and basil. Addition of high Cu compost influenced basil plant development. Plants from the 20 and 40% treatments had higher numbers of buds and flowers. There were no differences between the control and 60% compost treatments with respect to flower initiation. Addition of 20, 40 and 60% compost to the soil resulted in increased EXCH fractions of Cu, but not of Mn and Zn. Compost additions resulted in increase in the HNO(3) extractable, CARB, FeMnOX, and in OM fractions of Cu, Mn and Zn in soils. Compost application increased soil pH and EC, soil HNO(3) extractable Ca, K, Mg, P, Na, B and Pb, but did not alter soil HNO(3) extractable Cd, Co, Cr, Mo, Ni, Se. Increased rates of compost application decreased tissue Ca in basil, tissue Na in both plants, increased tissue K, Mg in both plants, but, did not alter tissue P, Co, Cr, Mo, Ni of either plants, and B in basil. Tissue As, Hg, Pb, and Se from all treatments were under the detection limits of VGA-AAS (for As, Hg, Se) and ICP (for Pb). Compost additions altered basil oil chemical composition. Copper in the essential oil of basil was below 0.25 mg/l. In conclusion, the addition of high rates of relatively immature high Cu compost may not always increase Cu concentration in plants and in plant oils.     

Metals contained and leached from rubber granulates used in synthetic turf areas

The aim of this study was to quantify metals contained in and leached from different types of rubber granulates used in synthetic turf areas. To investigate the total content of metals, ca 0.5 g of material was added with HNO₃, HF and HClO₄ and microwave digested with power increasing from 250 W to 600 W. Leachates were prepared by extraction of about 5.0 g of material at room temperature for 24 h in an acidic environment (pH 5). Leaching with deionized water was also performed for comparison. Aluminium, As, Ba, Be, Cd, Co, Cr, Cu, Hg, Fe, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, Tl, V, W and Zn were quantified by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and ICP optical emission spectrometry (ICP-OES).Results indicated that the developed method was accurate and precise for the multi-element characterization of rubber granulates and leachates. The total amount and the amount leached during the acidic test varied from metal to metal and from granulate to granulate. The highest median values were found for Zn (10,229 mg/kg), Al (755 mg/kg), Mg (456 mg/kg), Fe (305 mg/kg), followed by Pb, Ba, Co, Cu and Sr. The other elements were present at few units of mg/kg. The highest leaching was observed for Zn (2300 μg/l) and Mg (2500 μg/l), followed by Fe, Sr, Al, Mn and Ba. Little As, Cd, Co, Cr, Cu, Li, Mo, Ni, Pb, Rb, Sb and V leached, and Be, Hg, Se, Sn, Tl and W were below quantification limits. Data obtained were compared with the maximum tolerable amounts reported for similar materials, and only the concentration of Zn (total and leached) exceeded the expected values.     

Soil contamination by metals: A survey in industrial and rural areas of southern Italy

Samples of soil from agricultural land around the industrial district of the city of Bari in Apulia and from rural areas of that region were analyzed, by atomic absorption spectrophotometry, for levels of As, Bi, Cd, Cu, Hg, Mn, Ni, Pb, Se, Sn, and Zn.All elements, except Se, were present in all samples from the industrial district, whereas Hg was not detectable in the rural soils; Bi, Cd, and Sn were found only in 50–60% of them. The average levels of Hg, Cd, Cu, Mn, and Ni in soils close to the industrial area always appeared to be higher than the mean levels in rural soils and the common ranges known for world soils.The findings suggest the existence of a metal contamination of soils in the industrial area.     

Heavy metals in urban soils: a case study from the city of Palermo (Sicily), Italy

Concentrations of V, Mn, Cd, Zn, Ni, Cr, Co, Cu, Pb, Hg and Sb were measured on 70 topsoil samples collected from green areas and parks in the city of Palermo (Sicily) in order to: (1) assess the distribution of these heavy metals in the urban environment; (2) discriminate natural and anthropic contributions; and (3) identify possible sources of pollution. Mineralogy, physico-chemical parameters, and major element contents of the topsoils were determined to highlight the influence of 'natural' features on the heavy metal concentrations and their distribution. Medians of Pb, Zn, Cu and Hg concentrations of the investigated urban soils are 202, 138, 63 and 0.68 mgkg(-1), respectively. These values are higher, in some case by different orders of size, than those of unpolluted soils in Sicily that average 44, 122, 34 and 0.07 mg kg(-1). An ensemble of basic and multivariate statistical analyses (cluster analysis and principal component analysis) was performed to reduce the multidimensional space of variables and samples, thus defining two sets of heavy metals as tracers of natural and anthropic influences. Results demonstrate that Pb, Zn, Cu, Sb and Hg can be inferred to be tracers of anthropic pollution, whereas Mn, Ni, Co, Cr, V and Cd were interpreted to be mainly inherited from parent materials. Maps of pollutant distribution were constructed for the whole urban area pointing to vehicle traffic as the main source of diffuse pollution and also showing the contribution of point sources of pollution to urban topsoils.     

Heavy metal pollution profiles of dated sediment cores from hebe haven, Hong Kong

Eight sediment cores from Hebe Haven were collected and studied for metals including Cd, Cr, Cu, Fe, Ni, Pb, Zn and Ca. ²¹⁰Pb and ¹³⁷Cs activities were determined to date the time of deposition of the sediment. Hebe Haven is a yacht area and is close to the urbanized coast with several dyeing factories. Except Cd, the greatest enrichment was found at locations closest to the Ho Chung Stream which carried domestic and industrial wastewater to Hebe Haven. Concentrations as high as 0.930, 120, 131, 42.3 and 50.9 mg/kg were found for Cd, Cr, Zn, Cu and Pb, respectively. The corresponding enrichment factors are 13(Cd), 7.0(Cr), 2.9(Zn), 5.2(Cu) and 2.4(Pb). The extent of pollution diminishes from the riverine source. Cr is a typical example because its enrichment was mostly attributed to the nearby dyeing operation. The distribution of Cd appears more complicated. A maximum concentration of 3.60 mg/kg was found at a location far from Ho Chung Stream and with no nearby municipal or industrial activity. No significant Fe and Ni enrichment was found in the area. Ca in all cores decreases towards the sediment-water interface. It is probable that the abundance of shellfish has decreased as a result of excessive exploitation as seafood and pollution. ²¹⁰Pb activity and heavy metal concentrations of surficial layers have been “diluted” by excessive deposition of Fe-deficient particles. This likely indicates the rapid deposition of coarser and sandy particles during the construction of a nearby large housing estate. Some ²¹⁰Pb activity profiles have periodic low values in deeper layers, which should correspond to events of rapid deposition of erosion during heavy typhoons and rainstorms. Overall, the sedimentation rates calculated were in the range of 0.351–0.561 cm/yr. In one site (Core S4) close to the riverine source and with the best available dating data, the recent anthropogenic fluxes of heavy metals in μg cm⁻² yr⁻¹ are estimated as: 0.081(Cd), 22(Cr), 20(Zn), 6.4(Cu) and 7.4(Pb).     

Toxic metals in street and household dusts.

Street and household dusts have been sampled within the Lancaster area (U.K.), and analysed for Pb, Cd, Cr, Co, Cu, Ni and Zn. The concentration of each metal has been determined both as total and extractable metal, the latter referring to metal soluble in a 0.07N hydrochloric acid solution. The results are discussed in relation to the sources of the metals, and possible health hazards to children exposed to the dusts.     

Abnormal chromosome assessment of snakehead fish (Channa striata) affected by heavy metals from a reservoir near an industrial factory

This study aimed to investigate nine heavy metal concentrations (As, Cd, Cr, Pb, Cu, Fe, Zn, Mn and Ni) in water, sediment and snakehead fish (Channa striata) and to identify abnormal chromosomes in C. striata from a reservoir near an industrial factory and a reference area. Heavy metal concentrations were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The metal concentrations in the water, sediment and C. striata samples did not exceed the standard limit of Thailand, except for Cr concentrations, which exceeded water quality standards. The concentrations of Cd, Fe, Mn and Ni in C. striata samples between the reservoir and the reference area were significantly different (p < 0.05). The diploid chromosome number of C. striata from both areas was (2n = 42). Eight types of abnormal chromosomes were identified and classified as a single-chromatid gap, a single-chromatid break, centric fragmentation, a centric gap (CG), fragmentation, deletion, single-chromatid decomposition and iso-arm fragmentation. The most frequent abnormal chromosome in the samples was CG. The percentages of abnormal chromosomes in the C. striata samples from the reservoir near the industrial factory and the reference area were significantly different (p < 0.05) at 8.44 and 1.20, respectively.