Sequential extraction of sulfide-rich tailings remediated by the application of till cover,Kristineberg mine,northern Sweden

A sequential extraction has been carried out on sulfide-rich mine tailings. The purpose was to investigate how elements released by oxidation are secondarily retained in the tailings and the possible consequences of the remediation. After investigating the solid tailings, seven samples were chosen for sequential extractions. Two samples were oxidised, situated just above the oxidation front; two samples from just below the former oxidation front with increased concentrations of several elements; two unoxidised samples were from an intermediate depth, and the deepest sample was from the tailings-peat boundary at the bottom of the impoundment. Five phases were extracted: adsorbed/exchangeable/carbonate; labile organics; amorphous Fe-oxyhydroxides/Mn-oxides; crystalline Fe-oxides; and organics/sulfides. The addition from dried porewater to the extracted fractions has been calculated and considered as minor. In the oxidised tailings, the sulfide fraction still dominates for elements such as Fe, S, Cd, Co, Cu, Hg and Zn, although the concentrations are low compared to the unoxidised tailings. Generally, the second most important fraction is the adsorbed/exchangeable/carbonate fraction. Below the oxidation front, the sulfide content of the tailings sharply increases. In the secondary enrichment zone, the total element concentrations increase compared with the deeper unoxidised samples, mainly due to secondary retention. For some elements, secondary retention is greater than the total amount extracted for the deeper unoxidised samples. In the secondary enrichment zone the adsorbed/exchangeable/carbonate fraction represents approximately 20 wt.% or more for Cd, Co, Mn, Ni and Zn. The amorphous iron oxyhydroxide or the crystalline iron oxide fractions are less important at this level, although for As, Ba and Cu the amorphous iron oxyhydroxide fraction represents up to 20 wt.%. At the lower border of the enrichment zone, the total concentration for most metals is lower, but the importance of the adsorbed/exchangeable/carbonate fraction is further enhanced for Cd, Cu, Ni and Zn. These elements have 35-60 wt.% of the total amount from this fraction. For As, Cd, Cu, Ni and Pb, the secondary fractions extracted (extractions A-D) represent between 60 and 80 wt.% of the total content. At greater depth in the impoundment the relative importance of the adsorbed/exchangeable/carbonate fraction decreases, whilst the importance of amorphous iron oxyhydroxide and crystalline iron oxide fractions increases. The adsorbed/exchangeable/carbonate fraction is the most easily remobilised fraction. A raised groundwater table previously situated below the enrichment zone may result in the release of secondarily retained metals.     

Mobility of trace metals in pore waters of two Central European peat bogs

Vertical peat profiles can only be used as archives of past changes in pollution levels if atmogenic elements are immobile after their burial. For mobile elements, similar pore-water concentrations can be expected at different peat depths. Concentrations of Pb, Cu, Zn, Cr, Mn, Fe, Co and Cd were determined in surface bog water and bog pore water 40 cm below surface in two Sphagnum-dominated peat bogs in the Czech Republic. Velke jerabi jezero (VJJ) is an upland bog located in an industrial area, Cervene blato (CB) is a lowland bog located in a rural area. Metal concentrations were monitored seasonally over 3 years (2002--2005) at both sites. Higher concentrations of Pb, Cu, Zn, Cr and Cd and lower concentrations of Mn, Fe and Co were found at the less polluted CB compared to VJJ. No clear-cut seasonality was observed in metal concentrations in bog waters, despite seasonal differences in industrial emission rates of pollutants (more coal burning in winter than in summer). This contrasts with an earlier observation of distinct seasonality in sulfate concentration and isotope composition in these stagnating bog waters. Peat substrate 40 cm below current bog surface represented pre-industrial low-pollution environment, yet pore waters at such depths contained the same metal concentrations as surface waters. The only exception was Pb, whose concentration in water solutes increased with increasing depth. Lack of vertical stratification in pore-water contents of Cu, Zn, Cr, Mn, Fe and Co indicated vertical mobility of these metals.     

Long-term effects of the Aznalcóllar mine spill-heavy metal content and mobility in soils and sediments of the Guadiamar river valley (SW Spain)

In 1998, a toxic spill from a pyrite mine (Aznalcóllar, SW Spain) contaminated some 40 km2 of the Agrio and Guadiamar river valley with heavy metal-enriched tailings sludge and acidic mine water. The aim of this study is to describe the long-term effects of heavy metal migration particularly with respect to the extent of vertical redistribution of As, Cd, Cu, Fe, Pb, S, Sb and Zn in soils and sediments of the river Guadiamar 4 years after the accident. For an assessment of the mobility behaviour, chemical associations of Cu, Pb, Sb and Zn in depth profiles polluted by tailings were determined by using sequential extraction procedures. In 2002, residues of toxic tailings were found in several places along the river Guadiamar. Heavy weathering has accelerated heavy metal displacement and contamination of the surrounding soil. Two element groups of contrary mobility can be distinguished: Cd and Zn are highly mobile and show strong displacements in acidic surroundings. Accumulation zones for Cd and Zn develop in less acidic soil layers due to the occurrence of Fe oxides, which constitute retaining fractions for these elements. The immobile elements Pb and Sb represent the second group. Highest concentrations of Pb and Sb are found in the tailings sludge. Cu and As show a variable distribution pattern. As a consequence of the heavy metal migration, an accumulation zone has formed up to 30 cm into the underlying soil at the time of investigation. In the future, there may be further penetration of heavy metals to greater depths.     

Accumulation of heavy metals in a lake ecosystem

The concentrations of Cu, Zn, Fe, Mn, Ni, Cd, Pb and Co have been determined in water, bottom sediments, plankton, zoobenthos and ichthyofauna of mesotropic Lake Piaseczno located in eastern Poland. In water, sediments, plankton and benthos the most abundant heavy metals were Fe, Zn and Mn, whereas in fish Zn, Cu, and Mn were most abundant. The amount of heavy metals in the biotic components was dependent upon their concentration in water and partly upon the concentration in bottom sediments. A considerably less important role in the translocation of heavy metals is probably played by trophic interactions.     

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.     

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.     

Geochemistry of trace metals in a fresh water sediment: field results and diagenetic modeling

Concentrations of Fe, Mn, Cd, Co, Ni, Pb, and Zn were determined in pore water and sediment of a coastal fresh water lake (Haringvliet Lake, The Netherlands). Elevated sediment trace metal concentrations reflect anthropogenic inputs from the Rhine and Meuse Rivers. Pore water and sediment analyses, together with thermodynamic calculations, indicate a shift in trace metal speciation from oxide-bound to sulfide-bound over the upper 20 cm of the sediment. Concentrations of reducible Fe and Mn decline with increasing depth, but do not reach zero values at 20 cm depth. The reducible phases are relatively more important for the binding of Co, Ni, and Zn than for Pb and Cd. Pore waters exhibit supersaturation with respect to Zn, Pb, Co, and Cd monosulfides, while significant fractions of Ni and Co are bound to pyrite. A multi-component, diagenetic model developed for organic matter degradation was expanded to include Zn and Ni dynamics. Pore water transport of trace metals is primarily diffusive, with a lesser contribution of bioirrigation. Reactions affecting trace metal mobility near the sediment-water interface, especially sulfide oxidation and sorption to newly formed oxides, strongly influence the modeled estimates of the diffusive effluxes to the overlying water. Model results imply less efficient sediment retention of Ni than Zn. Sensitivity analyses show that increased bioturbation and sulfate availability, which are expected upon restoration of estuarine conditions in the lake, should increase the sulfide bound fractions of Zn and Ni in the sediments.     

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.     

Geochemical changes in sulfidic mine tailings stored under a shallow water cover

The objective of this study was to assess the effectiveness of an engineered shallow water cover in reducing the oxidation of sulfidic mine tailings and thus preventing the development of acid rock drainage. Fresh tailings were submerged under a 0.3-m water cover in experimental field cells. From 1996 to 1998, we followed the chemistry of the interstitial water near the tailings-overlying water interface using in situ dialysis, and determined pH and dissolved oxygen (DO) profiles across the tailing water interface using micro-electrodes. Penetration of DO into the tailings was limited to <7 mm, even in the presence of DO produced by benthic periphyton. Anoxia in the tailings was further demonstrated by the appearance of dissolved sigmaH2S, Fe and Mn in pore water at depths -1.5 cm below the interface. However, there was clear evidence of surface oxidation of the mine tailings at the mm scale (i.e., DO depletion, coupled with localized increases in [H+] and [SO4(2-)]). Mobilization of Cd and Zn from this surface layer was indicated by the presence of sub-surface peaks in the concentrations of these two metals in the tailings interstitial water and by a change in their solid phase partitioning from refractory to more labile fractions. In contrast, mobilization of Cu from tailings was less evident. Unlike previous reports, which suggested that submerged tailings were effectively inert, our results show alteration of the superficial layer over time.     

Adsorption of trace metals on aluminium oxide: A simulation of processes in freshwater systems by close approximation to natural conditions

The interaction of the trace metals Cu, Co, Zn, Ni, Pb and Cd with aluminium hydroxide precipitated in-situ from homogeneous solution was studied. Using total concentrations of 10⁻⁴ M Al, 10⁻⁷ M Zn, Cu, Co, Ni and 10⁻⁸ M Pb and Cd a removal of Zn, Cu, Pb, Cd from solution occurred together with Al, while Co and Ni concentrations in solution remained unchanged. The binding of Cu, Pb and Zn, Cd is in agreement with the effect predicted by using published (resp. evaluated for Zn and Cd), values for stability constants of surface complexes on preformed Al₂O₃-suspension. The different behaviour of these elements and of Co and Ni is expected from the hydrolysis and adsorption tendencies. The experimental conditions correspond to natural conditions in lake waters, where due to the pH-dependent solubility of aluminium hydroxide, in-situ precipitation may occur and cause the scavenging of trace elements.     

Estuarine capacity in removal of trace metals from contaminated river water, Southern Caspian Sea

In the present investigation, the flocculation of dissolved Cd, Cu, Ni, Pb, Mn and Zn with initial concentrations of 1, 2.5 and 5 mg/L in Tadjan River water during mixing with the Caspian Sea water has been studied in order to determine estuarine capacity to remove dissolved metals in the accidental contamination of the river. The flocculation process was investigated on a series of mixtures with salinities ranging from 0.1 to 11 p.p.t. The flocculation rates were indicative of the nonconservative behaviour of Cd, Cu, Ni, Pb, Mn and Zn during estuarine mixing. The order of the final flocculation rate of dissolved metals at 1, 2.5 and 5 mg/L of initial metal concentrations in the river water is as follows:Cu (99%)>Cd (95%)>Zn (88%)>Mn (85%)>Pb (83%)>Ni (73%), Cu(95.6%)>Pb(92.4%)>Cd (90%)>Zn(88.4%)>Mn (81.6%)>Ni(78.8%) and Cd (100%)>Cu(88%)>Ni (85.2%)>Pb (84%)>Zn (83.2%)>Mn (81.2%), respectively. The results also revealed that removal of dissolved metals is not influenced by pH changes and precipitation processes. The flocculation rates revealed that the overall dissolved metal pollution loads may be reduced to about 70% up to about more than 90% during estuarine mixing of Tadjan River with the Caspian Sea water.     

Trace metals in Shatt al-Arab River,Iraq

The distribution of 10 trace metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn have been determined along the northern section of the Shatt al-Arab River, Iraq. Analyses were carried out, employing a flameless AAS instrument. The mean concentrations of the dissolved species were as follows (expressed in μg l^?1): 0.25 Cd, 0.9 Cu, 716 Fe, 1.3 Mn, 0.3 Pb, 0.2 V and 1.8 Zn. Mean concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in the particulate matter were 55.2, 6.0, 188, 77, 31 472, 1731, 3807, 93, 207 and 77 μg g^?1 respectively. In the exchangeable fraction of the sediment were 0.15, 5.5, 11.1, 11.9, 1625, 482, 42, 30.5, 25.7 and 6 μg g^?1, whereas in the residual were 0.025, 11.5, 96.1, 22, 5176, 258, 613, 3.9, 162 and 56.8 μg g^?1 respectively. Thus, the exchangeable trace metals represent the following mean percentage of the total; 75% Cd, 33% Co, 10% Cr, 34% Cu, 24% Fe, 63% Mn, 7% Ni, 74% Pb, 14% V and 23% Zn. The concentration of Ni and V were relatively high, this was attributed to the petroleum-rich deposits of the region. The concentrations observed for other metals were lower or equal to those reported for control sites except for Pb which was slightly higher. The data obtained were subjected to simple linear regression analysis and expressed in the form of correlation coefficients. It was found that the inter-elemental relationships are rather complex.     

Assessment of heavy metal levels in Almendares River sediments--Havana City, Cuba

The Almendares River watershed covers a large portion of Havana, Cuba and is centrally important to both recreational and other activities in the region. In order to assess current water quality conditions prior to planned remediation efforts, the spatial distribution of six heavy metals and other compounds were determined in river sediments at fifteen sampling stations in the watershed. Metal concentrations in sediments ranged from 86.1 to 708.8 for Zn, 39.3 to 189.0 for Pb, 71.6 to 420.8 for Cu, 84.4 to 209.7 Cr, 1.5 to 23.4 for Co, and 1.0 to 4.3 for Cd microg/g dry weight sediment. Calculated enrichment factors (EF; measured metal versus background mineral conditions) were almost always greater than 1.0, suggesting significant anthropogenic impact on metal levels in the river. The highest EF values were seen immediately below Cotorro (EF>10 for Pb, Cu, and Cd), a suburban town that has an active secondary smelter, and below the largest municipal landfill in Havana (EF>10 for Pb, Cu, Cd, and Zn). Further, three sampling stations had multiple metals at concentrations higher than probable effects concentrations (PEC), implying possible local ecotoxicological impacts. Finally, sequential extractions of the sediments indicated that heavy metals were largely associated with the organic fraction, and it was estimated that up to 62% of metals in the sediments would be susceptible to release back into the water column if hydraulic or other changes occurred in the river. These data are being used to prioritize decisions related to the remediation of the river system.     

Adsorption of heavy metals on Na-montmorillonite. Effect of pH and organic substances

Clays (especially montmorillonite and bentonite) are widely used as barriers in landfills to prevent contamination of subsoil and groundwater by leachates containing heavy metals. For this reason it is important to study the adsorption of metals by these clays. The sorption of seven metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) on Na-montmorillonite was studied as a function of pH and in the presence of ligands, forming complexes of different stabilities with the metals of interest. The continuous column method was used as it better simulates natural conditions. The total capacity of Na-montmorillonite towards these metals was determined. The pH variations influence to a higher extent the concentrations of Cu, Pb and Cd in the effluent. Moreover the results suggest that complex formation hinders the sorption of the metals on the clay, with an increasing influence in the order: Mn < or = Pb < or = Cd < or = Zn < Ni < Cu < Cr. The evaluation of the total capacity of Na-montmorillonite shows that this clay is a good sorbent towards all examined metals.     

Bioaccumulation of heavy metals by the aquatic plants Potamogeton pectinatus L. and Potamogeton malaianus Miq. and their potential use for contamination indicators and in wastewater treatment

The concentrations of heavy metals in the leaves of two aquatic plants Potamogeton pectinatus L. and Potamogeton malaianus Miq., and the corresponding water and sediment samples from the Donghe River in Jishou City of Hunan Province, China were studied to investigate metal contamination from the intensive industrial activities in the surrounding area. Results showed that the concentrations of heavy metals in the sediments, especially Cd, Mn and Pb, were much higher than the eco-toxic threshold values developed by the U. S. Environmental Protection Agency. Between the two plant species, P. pectinatus showed the higher capacity in metal accumulation. The highest concentrations of Cd, Pb, Cu, Zn and Mn were found in the leaves of P. pectinatus, reaching 596, 318, 62.4, 6590 and 16,000 mg kg(-1) (DW), respectively. Significantly positive relationships were observed among the concentrations of Zn, Cu and Mn in the leaves of both aquatic plants and those in water, indicating the potential use of the two plants for pollution monitoring of these metals. In addition, a laboratory experiment was conducted to investigate the ability of P. pectinatus and P. malaianus to remove heavy metals from contaminated river water. The average removal efficiencies by P. pectinatus and P. malaianus for Cd, Pb, Mn, Zn and Cu from the spiked Donghe River water were 92%, 79%, 86%, 67% and 70%, respectively. The results indicated that P. pectinatus and P. malaianus had high capabilities to remove heavy metals directly from the contaminated water. The potential use of these plants in wastewater treatment is worth further exploration.     

Trace metals and water chemistry of forest lakes in northern Sweden

To study the influence of airborne pollutants on water quality, water samples were taken from 59 forest lakes in northern Sweden along a section of about 1000 km in length. Determinations were made of pH, water colour, conductivity, major ions, nitrogen and phosphorus, as well as the metals Fe, Mn, Al, Zn, Cu, Pb, Cd, Ni, Cr, Co, As and V.The lake waters were generally soft, with low levels of electrolytes. The pH values increased and the sulphate concentrations decreased from south to north. The lakes in the southern parts of the area showed evidence of increased deposition of acidifying substances, shown by higher Ca + Mg/alkalinity ratio.A geographical distribution pattern was observed from Zn and to some extent also for Pb and Cd, with the highest concentrations in the south. However, pH and water colour were of major importance for the distribution of trace metals. Mn, Al and Zn were negatively correlated to pH and Fe, Mn, Al, Pb and As were positively correlated to water colour. A multiple regression analysis showed that the distribution of Fe was influenced mainly by water colour, Zn mainly by pH, while Mn and Al were influenced both by pH and colour. Some of the lakes were sampled both in winter and summer and the concentration of metals was found to be around two-fold higher in winter than in summer.     

Natural attenuation processes in two water reservoirs receiving acid mine drainage

Characteristics of water profiles and sulphide formation processes in sediments were studied in two water reservoirs affected by acid mine drainage in order to investigate the mechanisms controlling the physical and chemical processes that, under favourable conditions, act to reduce the toxicity, mobility and concentration of metals and metalloids in the water column. Water columns and pore-waters from sediments were analysed for Fe species, trace elements (As, Cd, Co, Cu, Mn, Ni, Pb, Zn, Cr), sulphide, sulphate and bicarbonate. Inorganic reduced sulphur compounds (acid volatile sulphur, pyrite sulphur and elemental sulphur) and reactive Fe were determined in the sediments. A sequential extraction was also performed. Both reservoirs behave like holomictic and monomictic lakes, with a summer thermal stratification that disappears during winter. pH values between 4 and 7 can be observed along the water columns. Pore-water concentrations of up to 25 mg/l of Fe, 4 mg/l of Al, 1.3 mg/l of Zn, 170 µg/l of Pb, 11 µg/l of As, etc. have been found. The results suggest that toxic elements such as Cu, Zn, Co, Pb, Cr, As, etc. are mainly found in the bioavailable fraction which is the most hazardous for the environment. The calculated degree of sulphidization (DOS) and degree of pyritization (DOP) values indicates that removal of trace elements from anoxic pore-waters occurs by coprecipitation and/or adsorption on newly formed Fe sulphides (framboidal pyrite), attenuating the contamination. However oxidation of the sediments during turnover periods also occurs, which releases toxic elements back into the water column.     

Behavior of Mn, Fe, Cu, Zn, Cd and Pb discharged from a wastewater treatment plant into an estuarine environment

To obtain information on the fate of trace metals discharged to an estuarine environment, analyses have been made on water and sediment samples from Back River, MD., and on effluent from the large wastewater treatment plant that discharges there. Within 2–3 km of the outfall, the concentration (in μg 1⁻¹) of all metals decreases as follows: Mn, > 120-90; Fe, > 570-300; Cu, 53-7; Zn, 280-9; Cd, 3.5-0.5 and Pb, 31-<4. Except possibly for Mn and Fe, these decreases are much greater than can be ascribed to simple dilution, so physical, chemical or biological processes must be removing metals to the sediments. Correspondingly, sediment concentrations of Cu, Zn, Cd and Pb are approximately one order of magnitude higher than normally found in uncontaminated areas. After the initial decrease, concentrations of Mn and Cd in the water begin to rise again, suggesting remobilization from the sediments. Comparison of the estimated annual discharge of 8 trace metals to the Chesapeake Bay from wastewater treatment plants and from rivers suggests that the wastewater input may be within one order of magnitude of the fluvial input for Cr, Cu, Zn, Cd and Pb. Of the metals studied, Cd presents the greatest potential for serious pollution because its input from wastewater probably exceeds fluvial input, it appears to be readily remobilized from sediments, and it is known to be toxic to many organisms.     

Influence of liming on metal sequestration in lake sediments over recent decades

Sediment profiles from five limed and six reference softwater lakes included in Swedish monitoring programmes were subjected to multi-element analysis to investigate the influence of lime treatment since 1977 on the sequestration of metals in lake sediments. We hypothesised that liming causes increased sedimentation of elements for which the mobility is primarily controlled by pH, e.g. Al, Cd, Co, Ni and Zn, whereas elements that are less influenced by pH fluctuations, e.g. Hg and Pb, are not affected by lime treatment. Further, we introduce a normalisation of metal concentrations with respect to Cu concentration in order to separate the effects of lime treatment from those related to temporal trends in airborne metal deposition or short-term variations in environmental conditions. This approach is shown to emphasise the effect of liming on the sediment accumulation of metals, thus separating it from other sources of variability. We found that liming causes increased sequestration of Al, As, Cd, Co, Fe, Mn, Ni and Zn, in the case of As and Co probably at least partly caused by an increased adsorption to Al, Fe and Mn oxyhydroxides. On the other hand, no influence of lime treatment could be demonstrated for Hg, Pb, Cr, V and P, despite an increase of pH by about two units.     

A comparison of native and transplanted Fontinalis antipyretica Hedw. as biomonitors of water polluted with heavy metals

Native and transplanted mosses of the species Fontinalis antipyretica were studied to assess their capacity as biomonitors of heavy metals. Assays were carried out with transplanted mosses (sampled from an unpolluted control stream) exposed for 60 days to five streams polluted with heavy metals. At the same time, native mosses were collected from the exposure sites. Concentrations of N, P, K, Ca, Mg, S, Fe, Al, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn were determined in the mosses (native and transplants), stream waters, and sediments of both exposure and control sites. The results showed that the transplanted mosses accumulated significantly more Al, Cr, Cu, Pb, V, and Zn than the native mosses. The concentrations of Co and Mn in all streams were significantly higher in the native mosses.