Short-term temporal variations in speciation of Pb, Cu, Zn and Sb in a shooting range runoff stream

This study was designed to explore the changes in physico-chemical forms of Pb, Cu, Zn and Sb in a stream draining a contaminated shooting range, located at Steinsjøen in the South-Eastern part of Norway, during a period of 21 days. To obtain information on the element species distribution, an interphased size and charge fractionation system was applied, where membrane filtration (0.45 µm) and ultrafiltration using hollow fibre (nominal cut off 10 kDa) were performed prior to charge fractionation using chromatography (cationic and anionic exchange resins). The results show that Pb mainly was present as particulate and colloidal high molecular mass (HMM) species, Cu as colloidal (HMM) and low molecular mass (LMM) species, while Sb and Zn were mainly present as LMM species. The total element concentrations of Pb, Cu, Zn and Sb were positively correlated to water flow and dissolved organic carbon (DOC), suggesting these are important factors in controlling the run-off of the investigated elements in this catchment. During episodes of higher water flow, the increase in element concentration was mainly in the colloidal fraction. Partial redundancy analysis (pRDA) revealed that variations in pH, HMM organic carbon (HMM OC) and LMM organic carbon (LMM OC) explained 47% of the variation in size distribution of the elements, while variations in precipitation and water flow explained 48% of the variation in the charge distribution of the elements. The variation in concentrations during the period varied by a factor of 4, also stressing the importance of frequent sampling opposed to spot sampling in environmental surveys and risk assessments.     

Chemical and ecological effects of contaminated tunnel wash water runoff to a small Norwegian stream

Cleaning and washing of road tunnels are routinely performed and large volumes of contaminated wash water are often discharged into nearby recipients. In the present study, traffic related contaminants were quantified in tunnel wash water (the Nordby tunnel, Norway) discharged from a sedimentation pond to a nearby small stream, Årungselva. In situ size and charge fractionation techniques were applied to quantify traffic related metal species, while PAHs were quantified in total samples. All metals and several PAHs appeared at elevated concentrations in the discharged wash water compared with concentrations measured in Årungselva upstream the pond outlet, and to concentrations measured in the pond outlet before the tunnel wash event. In addition, several contaminants (e.g. Cu, Pb, Zn, fluoranthene, pyrene) exceeded their corresponding EQS. PAH and metals like Al, Cd, Cr, Cu, Fe and Pb were associated with particles and colloids, while As, Ca, K, Mg, Mo, Ni, Sb and Zn were more associated with low molecular mass species (< 10 kDa). Calculated enrichment factors revealed that many of the metals were derived from anthropogenic sources, originating most likely from wear of tires (Zn), brakes (Cu and Sb), and from road salt (Na and Cl). The enrichment factors for Al, Ba, Ca, Cr, Fe, K, Mg and Ni were low, suggesting a crustal origin, e.g. asphalt wear. Based on calculated PAH ratios, PAH seemed to originate from a mixture of sources such as wear from tires, asphalt and combustion. Finally, historical fish length measurement data indicates that the fish population in the receiving stream Årungselva may have been adversely influenced by the chemical perturbations in runoffs originating from the nearby roads and tunnels during the years, as the growth in summer old sea trout (Salmo trutta L.) in downstream sections of the stream is significantly reduced compared to the upstream sections.     

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.     

Market survey on toxic metals contained in tattoo inks

Tattooing practice is adopted worldwide and represents an important socio-cultural phenomenon, but, the injection into the skin of coloring agents as metals might pose a risk for allergies and other skin inflammations as well as for systemic diseases. In this context, 56 inks for tattooing purchased from 4 different supply companies were analyzed for metal concentration. Aliquots of pigments were microwave digested by nitric acid, fluoridric acid and hydrogen-peroxide and Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sr and V were quantified by sector field inductively coupled plasma mass spectrometry. Limits of quantification varied from 0.07 ng/ml (Cd) to 10 ng/ml (Al and Fe); recoveries ranged from 92% (Cd and Sb) to 109% (Sr); within- and between-day precisions were 3.2% and 4.67% on average.The relative contribution of metals to the tattoo inks composition was highly variable between brands and colors, even in pigments with the same base color. Elements found as the main components of inks were as follows (in µg/g): Al, 1.59–5893; Ba, 0.058–1226; Cu, 0.076–31,310; Fe, 0.717–88,443; Sr, 0.174–36.4. Toxic metals as Cd, Mn, Pb, Sb and V were over the 1 µg/g in a few cases, while Hg was in traces. Among the allergenic metals, Cr was the highest (0.315–147 μg/g), followed by Ni (0.037–9.59 μg/g) and Co (0.0028–6.43 μg/g) then. On 56 tattoo inks, Cr, Ni and Co exceeded the safe allergological limit of 1 µg/g in 62.5%, 16.1% and 1.8% of cases, respectively.     

Cu, Pb and Zn contamination in Nuuanu watershed, Oahu, Hawaii

Trace metal contamination in urban aquatic ecosystems in Hawaii is a significant problem, especially in terms of Cu, Pb, and Zn. These trace metals are linked to automobile usage. An in-depth study was designed to determine the influence of road sediments and storm sewers on bioavailable (0.5 M HCl) trace metal concentrations in bed sediments of Nuuanu stream, Oahu. Lead was the most enriched trace metal in the watershed. Compared to baseline Pb concentrations of <3 mg/kg, road sediments averaged 186 mg/kg, with a maximum value of 3140 mg/kg. Stream bed sediments had average Pb values of 122 mg/kg, with a maximum of 323 mg/kg. Al-normalized enrichment ratios (ERs) for the <63 microm fraction indicated that the watershed was significantly polluted in the lower, urbanized reaches, with maximum ER values of 560 and 94 for Pb in road sediments and stream sediments, respectively. Median ER values for Cu, Pb, and Zn in stream sediments were 2, 36, and 5, respectively. Rainfall events prior to sediment sampling masked any influence that storm sewer outlets might have had on the localized spatial distribution of metals associated with bed sediments. However, there was a general pattern of increasing trace metal concentrations downstream as the fluvial network traversed residential areas and commercial, highly trafficked areas in the lower portions of the watershed.     

Bromine,copper, manganese and lead content of the leaves of Taraxacum officinale (dandelion)

Neutron activation analysis and atomic absorption spectrometry have been used to determine the Br, Cu, Mn and Pb content of leaves of Taraxacum officinale (dandelion). The elemental content of the leaves correlated with the extent of anthropogenic pollution of the region where the plant developed. The dependence of the element concentrations on the distance from the source has been evaluated. A positive linear correlation was observed between the Cu and Pb, Cu and Sb, Pb and Cd, and Pb and Zn content of the leaves.     

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.     

A field survey of metal binding to metallothionein and other cytosolic ligands in liver of eels using an on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS)

The effect of metal exposure on the accumulation and cytosolic speciation of metals in livers of wild populations of European eel with special emphasis on metallothioneins (MT) was studied. Four sampling sites in Flanders showing different degrees of heavy metal contamination were selected for this purpose. An on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS) was used to study the cytosolic speciation of the metals. The distribution of the metals Cd, Cu, Ni, Pb and Zn among cytosolic fractions displayed strong differences. The cytosolic concentration of Cd, Ni and Pb increased proportionally with the total liver levels. However, the cytosolic concentrations of Cu and Zn only increased above a certain liver tissue threshold level. Cd, Cu and Zn, but not Pb and Ni, were largely associated with the MT pool in correspondence with the environmental exposure and liver tissue concentrations. Most of the Pb and Ni and a considerable fraction of Cu and Zn, but not Cd, were associated to High Molecular Weight (HMW) fractions. The relative importance of the Cu and Zn in the HMW fraction decreased with increasing contamination levels while the MT pool became progressively more important. The close relationship between the cytosolic metal load and the total MT levels or the metals bound on the MT pool indicates that the metals, rather than other stress factors, are the major factor determining MT induction.     

Distribution of some trace metals in Lochnagar, a Scottish mountain lake ecosystem and its catchment

Anthropogenic trace metals enter the entire ecosystem of Lochnagar solely through atmospheric deposition. Trace metals, including Hg, have been monitored in atmospheric deposition and lake water, and measured in catchment vegetation, aquatic plants and zooplankton, revealing contamination levels in the ecosystem. Furthermore, 17 sediment cores were taken from different areas of the lake. Hg, Pb, Cd, Zn and Cu were analysed in all the cores, which show that the sediments have been heavily contaminated by these trace metals since the 1860s. The distribution of trace metals in the lake sediments was found to be heterogeneous, with concentrations in the surface sediments varying significantly: 110-250 ng/g, 100-360 microg/g, 39-180 microg/g, 0.3-1.9 microg/g and 8-25 microg/g for Hg, Pb, Zn, Cd and Cu, respectively. Trends in the concentration profiles for different trace metals in the same core are different, as are the trends of the profiles for the same metal in different cores. Hence, a single sediment core cannot represent the pollution history of the whole lake. As the soils and sediments contain a high proportion of plant debris and the debris has a high affinity for Hg, resulting in Hg enrichment. Hg was measured in plant debris (> 63 microm) separated from catchment soils and lake sediments. Plant debris may play an important role in storing and transferring Hg in this ecosystem.     

The use of the red swamp crayfish (Procambarus clarkii, Girard) as indicator of the bioavailability of heavy metals in environmental monitoring in the River Guadiamar (SW, Spain)

A translocation experiment of red swamp crayfish (Procambarus clarkii) to different sites located in the River Guadiamar was performed in order to assess the ability of this species as bioindicator of heavy metal and metalloid contamination. Crayfish were placed in cages and exposed to polluted environment during either 6 or 12days in the three sites with different concentration of contaminants. Their tissues (exoskeleton+gills, hepatopancreas and abdominal muscle) were dissected and analysed by ICP-MS to assess for concentration of Cd, Cu, Zn, Pb and As. Both exposure times result in significant bioaccumulation of some metals in crayfish tissues as compared to their concentration in the environment. According to overall metal concentration, crayfish tissues rank as follows: hepatopancreas/viscera>exoskeleton/gills>abdominal muscle. Essential metals for crayfish metabolism (Cu and Zn) are always found in high concentrations independently of their quantities in the environment because of the ability of crayfish to manipulate their levels for their own metabolic profit. Metals not involved in crayfish metabolism (Cd, Pb, As) tend to increase with increasing concentration in the surrounding environment and with longer exposure times. Thus crayfish could be used as bioindicator of these pollutants because their dose- and time-dependent accumulation may be reflective of the levels of non-essential metals present in contaminated wetlands. Future guidelines in plans for monitoring contamination on polluted Mediterranean rivers and wetlands should take into account the implementation of the incubation of crayfish during 6days and their subsequent analyses of metal contents, as a routine.     

Short term and long term studies on individual and combined toxicities of copper,zinc and lead to Scenedesmus quadricauda

The toxicity of three metals (Cu, Zn, Pb) individually and in combination in a short term study (photosynthesis) and a long term study (growth) of a freshwater green alga, Scenedesmus quadricauda, was investigated. The relative metal toxicity to S. quadricauda was Cu > Zn ⪢ Pb, which corresponds with their respective electronegativities. This order was observed for both short term and long term studies. Specific individual and multiple heavy metal toxicities differed between short term and long term studies. Primary productivity was more sensitive to low concentrations of individual metals. Interactive effects between Cu, Zn and Pb were also assessed. In general, metal mixtures behaved antagonistically to photosynthesis. Both antagonism and synergism between Cu, Zn and Pb were observed to growth of S. quadricauda, although synergistic effects seemed to predominate.     

Metal accumulation and oxidative stress responses in, cultured and wild, white seabream from Northwest Atlantic

Metals are environmentally ubiquitous and can be found at high concentrations in seawater and subsequently in marine organisms. Metals with high redox potential can trigger oxidative stress mechanisms with damaging effects in biological tissues. In aquatic species, oxidative stress has been evaluated by assessing antioxidant enzymes activities and oxidative damages in tissues. The purpose of this study was to evaluate oxidative stress biomarkers and metal residues in white seabream (Diplodus sargus), a species entering aquaculture production in Portugal. Metal residues (Cu, Cd, As and Pb), in liver and muscle, as well as oxidative stress biomarkers were assessed at different stages in the life cycle of white seabream under culture conditions and in wild specimens, of a marketable size. Metal concentrations in tissues were low, and below the established limits. However, wild white seabream showed higher accumulation than cultured ones. Antioxidant enzymes, namely catalase (CAT) and superoxide dismutase (SOD), were correlated with metal accumulation. Oxidative damages to tissues were low, with wild white seabream showing lower levels than cultured fish. This study showed that white seabream has a good antioxidant defense system, capable of reducing oxidative damages in tissues resulting from the presence of metals.     

Dietary intake of heavy metals in Bombay city,India

Concentrations of heavy metals such as Pb, Cd, Cu and Zn have been estimated in air particulates, water and food samples collected from different suburbs in Bombay during 1991–1994. The concentrations of these metals are translated into intake rates through inhalation and ingestion pathways. Results indicate the highest concentration of Pb and Cu are in pulses (green gram), Cd in leafy vegetables (amaranth) and Zn in meat. Root vegetables and fruits contained a lower concentration of these metals. Total intakes of Zn, Cu, Pb and Cd through air, water and food were 10500 μg/day, 1500 μg/day, 30 μg/day and 4.3 μg/day, respectively. Although the major contribution for the daily intake is the ingestion route, eventual uptake in the body stream is contributed through inhalation for Pb (41%) and Cd (16%) and ingestion for Cu (98.8%) and Zn (99.6%). The total intake of these elements through the duplicate diet study is 9500 μg/day for Zn, 1770 μg/day for Cu, 27 μg/day for Pb and 2.5 μg/day for Cd, respectively. The daily intake of these metals by the population of Bombay is well below the recommended dietary values.     

Concentrations of 17 elements, including mercury, and their relationship to fitness measures in arctic shorebirds and their eggs

Exposure to contaminants is one hypothesis proposed to explain the global decline in shorebirds, and this is of particular concern in the arctic. However, little information exists on contaminant levels in arctic-breeding shorebirds, especially in Canada. We studied potential contaminants in three biparental shorebird species nesting in Nunavut, Canada: ruddy turnstones (Arenaria interpres), black-bellied plovers (Pluvialis squatarola) and semipalmated plovers (Charadrius semipalmatus). Blood, feathers and eggs were analyzed for As, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Tl, V, and Zn. We assessed whether element concentrations a) differed among species and sexes, b) were correlated among pairs and their eggs, and c) were related to fitness endpoints, namely body condition, blood-parasite load, nest survival days, and hatching success.Non-essential elements were found at lower concentrations than essential elements, with the exception of Hg. Maximum Hg levels in blood approached those associated with toxicological effects in other bird species, but other elements were well below known toxicological thresholds. Reproductive success was negatively correlated with paternal Hg and maternal Pb, although these effects were generally weak and varied among tissues. Element levels were positively correlated within pairs for blood-Hg (turnstones) and feather-Ni and Cr (semipalmated plovers); concentrations in eggs and maternal blood were never correlated. Concentrations of many elements differed among species, but there was no evidence that any species had higher overall exposure to non-essential metals. In conclusion, whereas we found little evidence that exposure to the majority of these elements is leading to declines of the species studied here, Hg levels were of potential concern and both Hg and Pb warrant further monitoring.     

The efficiency of oxidation ponds at the Kraft pulp and paper mill at Webuye in Kenya

Two streams of wastewater from the Kraft Pulp and Paper Mills at Webuye are released from the pulping, bleaching and paper pressing departments. One stream is made up of clear wastewater and the second is made up of turbid wastewater. The wastewaters from the mills are treated using oxidation ponds, after which the treated wastewater is discharged into the River Nzoia. The wastewater was analysed for Cd, Cr, Cu, Ni, Pb. Zn, Ca, K, Mg and Na. The results are that the concentrations of Ca and Na significantly increased in the treated wastewater. The concentrations of Cd, Pb, Zn, K and Mg also increased in the treated wastewater, though not significantly. The concentrations of Cr, Cu and Ni decreased in the treated wastewater but not significantly. Mass loadings of the metals discharged into River Nzoia were calculated. It was found that the mean mass loading of two metals (Ca and Na) significantly increased in the treated wastewater. Five metals (Cd, Pb, Zn, K and Mg) increased in the treated wastewater although not significantly. Three metals (Cr, Cu and Ni) decreased in the treated wastewater but the decrease was not significant. The concentrations of Cd, Cu, Ni, Pb and Zn were all above the limits set by EC for drinking water. These findings pose serious questions of the effectiveness of oxidation ponds system to safeguard the receptor against pollutants from the pulp and paper industry at Webuye.     

Pollution of montane soil with Cu, Zn, As, Sb, Pb, and nitrate in Kanto, Japan

Soil cores and rainwater were sampled under canopies of Cryptomeria japonica in four montane areas along an atmospheric depositional gradient in Kanto, Japan. Soil cores (30 cm in depth) were divided into 2-cm or 4-cm segments for analysis. Vertical distributions of elemental enrichment ratios in soils were calculated as follows: (X/Al)_i/(X/Al)_BG (where the numerator and denominator are concentration ratios of element-X and Al in the i- and bottom segments of soil cores, respectively). The upper 14-cm soil layer showed higher levels of Cu, Zn, As, Sb, and Pb than the lower (14-30 cm) soil layer. In the four areas, the average enrichment ratios in the upper 6-cm soil layer were as follows: Pb (4.93) ≥ Sb (4.06) ≥ As (3.04) > Zn (1.71) ≥ Cu (1.56). Exogenous elements (kg/ha) accumulated in the upper 14-cm soil layer were as follows: Zn (26.0) > Pb (12.4) > Cu (4.48) ≥ As (3.43) ≥ Sb (0.49). These rank orders were consistent with those of elements in anthropogenic aerosols and polluted (roadside) air, respectively, indicating that air pollutants probably caused enrichment of these elements in the soil surface layer. Approximately half of the total concentrations of As, Sb, and Pb in the upper 14-cm soil layer were derived from exogenous (anthropogenic) sources. Sb showed the highest enrichment factor in anthropogenic aerosols, and shows similar deposition behavior to NO₃⁻, which is a typical acidic air pollutant. There was a strong correlation between Sb and NO₃⁻ concentrations in rainfall (e.g., in the throughfall under C. japonica: [NO₃⁻] = 21.1 [dissolved Sb], r = 0.938, p < 0.0001, n = 182). Using this correlation, total (cumulative) inputs of NO₃⁻ were estimated from the accumulated amounts of exogenous Sb in soils, i.e., 16.7 t/ha at Mt. Kinsyo (most polluted), 8.6 t/ha at Mt. Tsukuba (moderately polluted), and 5.8 t/ha at the Taga mountain system (least polluted). There are no visible ecological effects of these accumulated elements in the Kanto region at present. However, the concentrations of some elements are within a harmful range, according to the Ecological Soil Screening Levels determined by the U.S. Environmental Protection Agency.     

Effect of imposed anaerobic conditions on metals release from acid-mine drainage contaminated streambed sediments

Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerobic streambed sediments collected from North Fork Clear Creek, Colorado were held under anaerobic conditions for four months. Eh, pH, and concentrations of Cd, Cu, Fe, Mn, and Zn (filtered at 1.5 μm, 0.45 μm, and 0.2 μm), sulfate, and dissolved organic carbon (DOC) were monitored in stream water/sediment slurries. Two sediment size fractions were examined (2 mm-63 μm and <63 μm). Sequential extractions evaluated the mineral phase with which metals were associated in the aerobic sediment. Released Cu was re-sequestered within 5 weeks, while Fe and Mn still were present at 16 weeks. Mn concentration was lower than in the initial stream water at and beyond 14 weeks for the smaller sized sediment. Cd was not released from either sediment size fraction. Zn was released at early times, but concentrations never exceeded those present in the initial stream water and all was re-sequestered over time. The greatest concentrations of Cu, Fe, Mn, and Zn were associated with the Fe/Mn reducible fraction. Sulfate and Fe were strongly correlated (r = 0.90), seeming to indicate anaerobic dissolution of iron oxy-hydroxy-sulfate minerals. DOC and sulfate were strongly correlated (r = 0.81), with iron having a moderately strong correlation with DOC (r = 0.71). Overall concentrations of DOC, sulfate, Cu, Fe, and Zn and pH were significantly higher (p < 0.05) in the water overlying the small sized sediment samples, while the concentrations of Mn released from the larger sized sediment samples were greater.     

Regional lead isotope study of a polluted river catchment: River Wear, Northern England, UK

High precision, lead isotope analyses of archived stream sediments from the River Wear catchment, northeast England (1986-88), provide evidence for three main sources of anthropogenic lead pollution; lead mining, industrial lead emissions and leaded petrol. In the upper catchment, pollution is totally controlled and dominated by large lead discharges from historic mining centres in the North Pennine Orefield (²⁰⁸Pb/²⁰⁶Pb, ²⁰⁷Pb/²⁰⁶Pb ratios range from 2.0744-2.0954 and 0.8413-0.8554 respectively). In the lower catchment, co-extensive with the Durham Coalfield and areas of high population density, pollution levels are lower and regionally more uniform. Isotope ratios are systematically higher than in the upper catchment (²⁰⁸Pb/²⁰⁶Pb, ²⁰⁷Pb/²⁰⁶Pb ratios range from 2.0856-2.1397 and 0.8554-0.8896 respectively) and far exceed values determined for the geogenic regional background. Here, the pollution is characterised by the atmospheric deposition of industrial lead and petrol lead. Lead derived from the combustion of coal, although present, is masked by the other two sources. Recent sediments from the main channel of the River Wear are isotopically indistinguishable from older, low order stream sediments of the North Pennine Orefield, indicating that contamination of the river by lead mining waste (up to several 1000 mg/kg Pb at some locations) continues to pose an environmental problem; a pattern that can be traced all the way to the tidal reach. Using within-catchment isotope variation and sediment lead concentrations, estimates can be made of the discharges from discrete mines or groups of mines to the overall level of lead pollution in the River Wear. As well as providing information pertinent to source apportionment and on-going catchment remediation measures, the database is a valuable resource for epidemiologists concerned with the health risks posed by environmental lead.     

Sources, nature, and fate of heavy metal-bearing particles in the sewer system

A preliminary insight into metal cycling within the urban sewer was obtained by determining both the heavy metal concentrations (Cu, Zn, Pb, Cd, Ni, Cr) in sewage and sediments, and the nature of metal-bearing particles using TEM–EDX, SEM–EDX and XRD. Particles collected from tap water, sump-pit deposits, and washbasin siphons, were also examined to trace back the origin of some mineral species. The results show that the total levels in Cu, Pb, Zn, Ni, and Cr in sewage are similar to that reported in the literature, thus suggesting that a time-averaged heavy metal fingerprint of domestic sewage can be defined for most developed cities at the urban catchment scale. Household activities represent the main source of Zn and Pb, the water supply system is a significant source of Cu, and in our case, groundwater infiltration in the sewer system provides a supplementary source of Ni and Cd. Concentrations in heavy metals were much higher in sewer sediments than in sewage suspended solids, the enrichment being due to the preferential settling of metal-bearing particles of high density and/or the precipitation of neoformed mineral phases. TEM and SEM–EDX analyses indicated that suspended solids, biofilms, and sewer sediments contained similar heavy metal-bearing particles including alloys and metal fragments, oxidized metals and sulfides. Copper fragments, metal carbonates (Cu, Zn, Pb), and oxidized soldering materials are released from the erosion of domestic plumbing, whereas the precipitation of sulfides and the sulfurization of metal phases occur primarily within the household connections to the sewer trunk. Close examination of sulfide phases also revealed in most cases a complex growth history recorded in the texture of particles, which likely reflects changes in physicochemical conditions associated with successive resuspension and settling of particles within the sewer system.     

The distribution of cadmium,copper, lead,and zinc in eelgrass (Zostera marina L.)

The distribution of Cd, Cu, Pb, and Zn in eelgrass (Zostera marina L.) was studied at three locations with different heavy metal loads in the Limfjord, Denmark.The eelgrass was fractionated into roots, rhizome, stem, and leaves according to age, and the heavy metal concentrations in each fraction were determined. The distribution patterns of the four heavy metals in eelgrass were independent of the heavy metal loads at the sampling stations. The concentrations of all metals were greater in the roots than in the rhizomes. In the aerial¹ parts two different age-dependent distribution patterns were observed. The concentrations of Cd, Pb, and Zn increased with age while the opposite was true for Cu. The distribution of lead correlated with the distribution of ash content. These age-dependent distribution patterns were maintained throughout the observation period and were most pronounced for Cu and Zn in winter.The heavy metal distribution in eelgrass is discussed in relation to gross morphology, especially age-structure. It is suggested that the accumulation of Cd, Pb, and Zn is due to a slow irreversible uptake or to the existence of more binding sites in old leaves. The distribution of Cu can be explained by translocation within the plant, dilution due to growth or leakage from the older leaves.