Residual effects of lead and zinc mining on freshwater mussels in the Spring River Basin (Kansas, Missouri, and Oklahoma, USA)

Concentrations of selected trace elements in surface water and fluvial sediment were investigated as possible factors limiting the distribution and abundance of freshwater mussels in the Spring River Basin, a 6600 km(2) watershed overlapping a former Pb and Zn mining and ore processing district in the central USA. Mussel taxa richness surveys and supporting physical habitat assessments were performed in 23 stream reaches dispersed throughout the basin and above and below former mining sites. Quantitative mussel density surveys were performed in the Spring River at one upstream reference location and one downstream location. Concentrations of 16 trace elements in the soft tissues of mussels and Asian clams (Corbicula fluminea) were determined at most survey sites. Comparable analyses were performed on surface water samples collected during base flow and peak flow synoptic surveys and sediment samples collected during base flow periods. Sites on the Spring River immediately upstream of heavily mined areas supported at least 21-25 species of mussels, whereas sites near the lower terminus of the river yielded evidence of 6-8 extant species. Between the upper and lower quantitative survey sites, mean mussel and clam densities declined by 89% and 97%, respectively. Tributary reaches below heavily mined areas lacked evident bivalve communities and contained concentrations of Cd, Pb, and Zn that continually or sporadically exceeded hardness-dependent water quality criteria and consensus-based sediment quality guidelines (probable effect concentrations). In less contaminated stream reaches supporting bivalves, concentrations of Cd, Pb, and Zn in mussels and clams were correlated spatially with the levels occurring in surficial sediment (0.50 < or = tau < or = 0.64, p < or = 0.03). In non-headwater perennial stream reaches, sediment Cd, Pb, and Zn levels were related inversely to mussel taxa richness (-0.80 < or = tau < or = -0.64, p < or = 0.004). Metal contaminant burdens in mussels and clams fluctuated measurably in association with variable stream flow conditions and accompanying changes in surface water and sediment chemistry. Concentrations of Cd, Pb, and Zn in mussels approximately paralleled the levels measured in composite clam samples (0.74 < or = tau < or = 0.79, p<0.001), implying C. fluminea could serve as a possible surrogate for native mussels in future metal bioaccumulation studies. Overall, streams draining heavily mined areas exhibited depauperate (or fully extirpated) mussel assemblages and correspondingly elevated concentrations of Cd, Pb, and Zn in water, sediment, and bivalve tissue. Other evaluated environmental chemistry parameters, and physical habitat conditions assessed at the stream reach scale, demonstrated little general relationship to the degraded status of these assemblages. We conclude that pollution attributable to former mining operations continues to adversely influence environmental quality and impede the recovery of mussel communities in a large portion of the Spring River Basin.     

Identifying the origins of local atmospheric deposition in the steel industry basin of Luxembourg using the chemical and isotopic composition of the lichen Xanthoria parietina

Trace metal atmospheric contamination was assessed in one of the oldest European industrial sites of steel production situated in the southern part of the Grand-Duchy of Luxembourg. Using elemental ratios as well as Pb, Sr, and Nd isotopic compositions as tracers, we found preliminary results concerning the trace metal enrichment and the chemical/isotopic signatures of the most important emission sources using the lichen Xanthoria parietina sampled at 15 sites along a SW-NE transect. The concentrations of these elements decreased with increasing distance from the historical and actual steel-work areas. The combination of the different tracers (major elements, Rare Earth Element ratios, Pb, Sr and Nd isotopes) enabled us to distinguish between three principal sources: the historical steel production (old tailings corresponding to blast-furnace residues), the present steel production (industrial sites with arc electric furnace units) and the regional background (baseline) components. Other anthropogenic sources including a waste incinerator and major roads had only weak impacts on lichen chemistry and isotopic ratios. The correlation between the Sr and Nd isotope ratios indicated that the Sr-Nd isotope systems represented useful tools to trace atmospheric emissions of factories using scrap metal for steel production.     

Atmospheric pollution for trace elements in the remote high-altitude atmosphere in central Asia as recorded in snow from Mt. Qomolangma (Everest) of the Himalayas

A series of 42 snow samples covering over a one-year period from the fall of 2004 to the summer of 2005 were collected from a 2.1-m snow pit at a high-altitude site on the northeastern slope of Mt. Everest. These samples were analyzed for Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Cd, Sb, Pb, and Bi in order to characterize the relative contributions from anthropogenic and natural sources to the fallout of these elements in central Himalayas. Our data were also considered in the context of monsoon versus non-monsoon seasons. The mean concentrations of the majority of the elements were determined to be at the pg g(-1) level with a strong variation in concentration with snow depth. While the mean concentrations of most of the elements were significantly higher during the non-monsoon season than during the monsoon season, considerable variability in the trace element inputs to the snow was observed during both periods. Cu, Zn, As, Cd, Sb, and Bi displayed high crustal enrichment factors (EF(c)) in most samples, while Cr, Ni, Rb, and Pb show high EF(c) values in some of the samples. Our data indicate that anthropogenic inputs are potentially important for these elements in the remote high-altitude atmosphere in the central Himalayas. The relationship between the EF(c) of each element and the Al concentration indicates that a dominant input of anthropogenic trace elements occurs during both the monsoon and non-monsoon seasons, when crustal contribution is relatively minor. Finally, a comparison of the trace element fallout fluxes calculated in our samples with those recently obtained at Mont Blanc, Greenland, and Antarctica provides direct evidence for a geographical gradient of the atmospheric pollution with trace elements on a global scale.     

Mineralogy and geochemistry of donax shells along the mediterranean coast of Egypt

Donax is an edible and very popular seafood along the Mediterranean coast of Egypt. A lot of pockets composed of empty Donax shells are on the shoreline among many areas along the coast. Some major (Ba, Ca), minor (Mg and Sr) and trace (Al, Cd, Co, Cr, Cu, Fe, Mn, Sb and Zn) elements were determined in the Donax shells as a carbonate source. In addition, Cd, Pb, Cu and Zn were measured in both the soft tissue and the sediment as well.     

Distribution of 7Be, 210Pb and 137Cs in watersheds of different scales in the Seine River basin: inventories and residence times

The activity of environmental radionuclides ((7)Be, (210)Pb and (137)Cs) was monitored in nested catchments, inside the Seine River basin. Suspended matter data was collected at 8 different watersheds, ranging from order 1 to order 7, and ranging in size over 4 orders of magnitude. Suspended matter was analyzed for (210)Pb, (137)Cs and (7)Be, and used to calculate the flux of sediments out of each watershed. Monthly atmospheric flux data of (210)Pb and (7)Be was analyzed to assess the input flux of each into the watersheds, taking into account the rainfall during sampling periods. Taking advantage of the different half-lives of (7)Be (53 days) and (210)Pb (22 years), a two-box model was built for each of the catchments following a methodology previously developed by Dominik et al. [Dominik J, Burrus D, Vernet JP. Transport of the environmental radionuclides in alpine watershed. Earth Planet Sci Letters 1987; 84: 165-180.]. The model divides the watershed into a soil box and a rapid reservoir and provides insight into the removal rate of suspended matter from the surrounding watershed. The model enables the assessment of the surface area and the residence time of slow and rapid reservoirs to describe the fate of contaminants of atmospheric origin inside the river basin. The model was improved by considering the dissolved fraction in the total flux and adding the (137)Cs inventory as an additional constraint. The effects of these changes are discussed. Residence times in the soil box, characterized by low transport velocity, range between 4800 years at Melarchez (order 1) to about 30000 years at Andresy and Poses (order 7). They remain constant in each watershed over a large range of variation of atmospheric fluxes of (7)Be and (210)Pb during the whole study, but are sensitive to SM variations. The residence time in the rapid box, which includes the surface of the river and immediate surroundings, is less than one year, while its surface area is in the range 0.6% to 2.2% of the total catchment area. They are sensitive to (7)Be atmospheric flux variations. The two-box model was used to estimate the amount of the radionuclides in each reservoir. Inventories appear to be constant from one watershed to the next. The (7)Be inventory ratio in the rapid and slow boxes expresses the rate of particle-reactive atmospheric pollutants that will be rapidly delivered to the river.     

Short-term variability of dissolved trace element concentrations in the Marne and Seine rivers near Paris

The concentrations of dissolved trace elements (Li, B, Mn, Cu, As, Rb, Sr, Mo, Cd, Ba, Pb) in the Marne and Seine rivers in the Paris urban area were monitored over a 2-year period. The resulting data indicated moderate contamination of waters by the most toxic elements (Cu, As, Cd and Pb). The River Marne upstream and the River Seine downstream of the city of Paris displayed similar concentrations. However higher fluxes of trace elements were observed in the Seine than in the Marne due to their different discharges. Li, B, Rb, Sr and Ba concentrations were correlated with river discharge and concentrations were higher during high river flow. This was interpreted as a dilution by discharge from a major natural or anthropogenic source. Mn, Cu, Mo, Cd and Pb concentrations were not correlated with discharge. Dissolved Mn, Cu and Cd increased rapidly in summer, whereas the concentration of Mo decreased. These variations were attributed to redox processes. During summer when the dissolved oxygen concentrations decrease, Mn, Cu, Cd and Pb are released into solution whereas Mo is immobilised. Like metals, variations in arsenic contents were not linked with discharge. Its similarity with phosphate distribution suggests similar controls involving phytoplankton uptake and release from sediments through organic matter mineralization.     

Geochemical signals and source contributions to heavy metal (Cd, Zn, Pb, Cu) fluxes into the Gironde Estuary via its major tributaries

Daily measurements of water discharges and suspended particulate matter (SPM) concentrations and monthly sampling for trace element analyses (Cd, Zn, Pb and Cu) were conducted from 1999 to 2002 on the Garonne, Dordogne and Isle Rivers, the three main tributaries of the Gironde Estuary, France. Dissolved and particulate Cd, Zn, Pb and Cu concentrations in the Isle River were generally higher than those in the Garonne River, despite the known historical polymetallic pollution affecting the Lot-Garonne River system. Even if the relatively high dissolved metal concentrations in the Isle River may be of importance for the local ecosystem, metal inputs into the estuarine and coastal zones are mainly controlled by fluvial transport via the Garonne River. Characteristic element concentration ratios (e.g., Zn/Pb) in SPM and stream sediments from the Dordogne and Isle Rivers suggest two different metal source areas with distinct geochemical signals. Low Zn/Pb ratios (<8) and low Cu/Pb ratios (<0.8) have been attributed to upstream source zones in the Massif Central, featuring various ore deposits and mining areas. High Zn/Pb ratios were assigned to downstream sources (e.g., vineyards), partly explaining high Zn and Cu concentrations and high Cu/Pb ratios (>0.8) in SPM. Although SPM derived from the upstream parts of the studied watersheds may greatly contribute to the observed fluvial metal transport (up to approximately 80% for Pb), the results suggest that intensive agriculture also considerably influences gross metal (e.g., Zn, Cu) fluxes into the Gironde Estuary. Relative contributions of upstream and downstream source zones may vary from one year to another reflecting hydrological variations and/or reservoir management. Monitoring fluxes and identifying distinct geochemical signals from source areas in heterogeneous watersheds may greatly improve understanding of contaminant transport to the coast.     

浙江省燕山期花岗岩化学元素丰度及特征

本研究从浙江省87个燕山期花岗岩体中系统采集了189件样品,采用等离子体光谱法等11种分析方法,获得了Ag、As、Au、B、Ba、Be、Bi、Br、Cd、Cl、Co、Cr、Cs、Cu、F、Ga、Ge、Hf、Hg、I、In、Li、Mn、Mo、N、Nb、Ni、P、Pb、Rb、S、Sb、Sc、Se、Sn、Sr、Ta、Te、Th、Ti、Tl、U、V、W、Zn、Zr、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y、SiO₂、Al₂O₃、TFe₂O₃、MgO、CaO、K₂O、Na₂O共68项主量、微量、稀土元素值以及TC、pH的实测数据,计算了扬子板块东缘与华南造山带燕山期花岗岩的化学元素丰度。岩石地球化学特征显示,这些花岗岩为高硅、富碱、弱过铝质的高钾钙碱性花岗岩,具有较强的Eu负异常,富集Rb、Th、U、K,亏损Sr、Ba、P、Ti、Nb、Ta等元素的特征,其普遍富铝和低MgO含量的岩石化学特征,指示它们的岩浆源区以壳源为主。     

Impact of fertilizer on a small watershed of Lake Biwa: use of sulfur and strontium isotopes in environmental diagnosis

Sulfur and strontium isotopes (delta(34)S and (87)Sr/(86)Sr) were determined in 39 river water samples collected over three different cultivation periods (April, May, and June), and in several materials used for comparison (fertilizers, detergents, soils, irrigation and agricultural waters), to evaluate the impact of fertilizers on a small agricultural watershed of Lake Biwa, in central Japan. delta(34)S values in river water decreased (from +5.8 to -2.0 per thousand) with increasing SO(4) concentrations (3.8 to 93.2 ppm) from upstream to downstream of the watershed. Comparison of river water S isotopes with those of possible source materials indicates that the enrichment of SO(4) can be attributed to the dissolution of two kinds of fertilizers: (1) compound fertilizers commonly used in this area and (2) ammonium sulfate which is applied on a small scale. In contrast, (87)Sr/(86)Sr values of river water decreased with time from April (avg. 0.71163), through May (avg. 0.71139), to June (avg. 0.71127). The tendency of the sample plots on the (87)Sr/(86)Sr vs. 1/Sr diagram suggests a time-dependent increase in the contribution of soil water to the river, which is partly affected by the Sr-bearing fertilizers. It is suggested that a maximum of 25% of dissolved Sr is derived from these fertilizers, while more than 75% of it is of rock origin. Mass balance calculations permitted us to evaluate the proportion of fertilizer contribution in each river. Combined use of S and Sr isotopes together with concentration data could be a new environmental diagnosis technique for rivers and soils in localized watersheds.     

Metal phase associations in soils from an urban watershed, Honolulu, Hawaii

Soils of Manoa watershed, Hawaii, have received varying inputs of anthropogenic trace metals, with roadside soils primarily influenced by automobile contributions. A four-stage sequential extraction procedure was used to fractionate 13 topsoil (0-2.5 cm) and 13 subsoil (7.5-10.0 cm) samples into: (i) an adsorbed, exchangeable and carbonate (AEC) phase; (ii) a reducible phase; (iii) an oxidizable phase; and (iv) a residual phase. Phases (i)-(iii) were considered 'labile', with the residual fraction 'non-labile' under normal circumstances. An examination of eight elements (Al, Co, Cu, Fe, Mn, Ni, Pb and Zn) indicated that Pb was the trace metal most impacted by anthropogenic inputs. Roadside soil Pb enrichment was apparent with data from a 0.5 M HCI leach exhibiting a maximum concentration of 1000 mg/kg compared with a median background value of 12 mg/kg. Sequential extraction results indicated the following order with respect to phase dominance for Pb: reducible > residual > oxidizable > AEC. The identification of the reducible phase as the primary pool of available Pb supports previous work from temperate roadside soil environments. The reducible phase is characterized by hydrous Fe and Mn oxides and mobilization of fixed elements can occur with decreases in pH and redox potential. Iron was the least labile of the elements examined with only 5-6% of total Fe removed by the first three steps of the extraction procedure. Lead had the highest labile percentage with average values between 74 and 81%. Therefore, results from this study support earlier research in this watershed which identified Pb as the primary trace metal of concern from a contamination perspective.     

Heavy-metal pollution of sediments from Szczecin Lagoon and the Gdansk Basin, Poland

Concentrations of Al, V, Mn, Fe, Co, Cu, Ni, Zn, Sr, Mo, Cd, Sb, Pb, Th, U, REE, Na, K, Mg, Ca, Si, P, S, Ti, Cr and Ba were determined in the <63 microm fraction of bottom sediments of the Szczecin Lagoon and the Gdansk Basin, Baltic Sea, by ICP-MS, ICP-AES and XRF methods. Sediment samples from the Szczecin Lagoon displayed somewhat higher concentrations of P, Mn, Cr, Cu and possibly Cd, Pb and Zn in those collected in October 1997 after the exceptional flooding of the Oder River than in those collected in December 2000. The data suggest that the flood resulted in the enhanced transport of redox-sensitive and anthropogenic elements in the Oder River and their subsequent redeposition mainly in the western part of Szczecin Lagoon. The sediments of the Szczecin Lagoon also appear to be the most polluted with heavy metals within the Polish Exclusive Economic Zone (EEZ) of the Baltic Sea. Cd, Pb, Zn and Cu are anthropogenically enriched in top layers of sediment cores from the Gdansk Basin, but the decrease of these elements with depth in the core is not systematic. The rare earth element (REE) patterns in sediments from both these areas do not appear to have been greatly modified during transport from their source into the southern Baltic. Factor analysis (FA) of the compositional data shows that sediments from Szczecin Lagoon can be divided into three main groups depending on their composition. It is concluded that clay minerals and organic matter build aggregates and flocs, which effectively concentrate trace metals and sink down to form a 'fluffy layer'.     

Emissions of mercury and other trace elements from coal-fired power plants in Japan

To evaluate trace element emissions from modern coal-fired power plants into the atmospheric environment in Japan, trace elements in the coal used in electric utility boilers, stack concentrations, emission rates and emission ratios of coal-fired power plants, and proportions of trace elements in coal-fired power plants were studied. The elements were As, B, Be, Cd, Co, Cr, F, Hg, Mn, Ni, Pb, Sb, Se and V, which are designated in the Law of Pollutant Release and Transfer Register. The particulate trace elements were collected in an electrostatic precipitator and a wet desulfurization scrubber. Emissions into the atmosphere were lower than 1% of the quantity in coal, but the volatile trace elements showed somewhat higher emission ratios. For mercury, the mean concentration in coal was 0.045 ppm, the mean emission rate was 4.4 microg/kW h, and the mean emission ratio was 27%, the highest ratio among all elements in this study. The total annual emission of mercury from coal-fired power plants of the electric power industry in Japan was estimated to be 0.63 t/y. On the basis of these data, the atmospheric environment loads from a coal-fired power station were investigated. The calculation of stack gas dispersion showed that maximum annual mean ground level concentrations were in the order of 10(-2) to 10(-5) of the background concentrations, and that the adverse effect of the emissions from the coal-fired power station was small.     

A Pb isotope and trace element study of rainwater from the Massif Central (France)

Lead isotope ratios and Zn, Pb, Cu, Cd, Sb and Rb contents were measured in samples of rainwater collected over a period of 15 months from the Massif Central (France). Each sample, collected automatically at monthly intervals, represents a series of rainfall events. Rainwater chemistry was interpreted in terms of the chemical contributions from wet deposition and from different source regions for dust in the centre of France. Trace element concentrations in rainwater samples showed a wide range, particularly for Pb (1.30-465 microg/l), with variations decreasing for Cd (0.07-1.70 microg/l), Zn (1.00-54.00 microg/l), Cu (0.20-25.00 microg/l), Sb (approximately 0-0.33 microg/l) and Ni (approximately 0-15.00 microg/l). Trace element contents do not correlate with rainfall amount and no inter-element correlations are evident in the data. Lead is the most common trace metal found in the rainwater (mean value = 996 microg/m2/y) while Sb is the least common element measured (mean value = 1.12 microg/m2/y). The composition of rainwater collected from the Massif Central shows a range in Pb isotope ratios from 17.935 to 19.22 (206Pb/204Pb), 15.578 to 15.73 (207Pb/204Pb) and 37.559 to 38.606 (208Pb/204Pb). A five-component mixing model involving contributions from the natural background, gasoline inputs from industrial and agricultural activity and a source resulting from mining waste may be used to explain both the Pb isotope signature and the fluctuations in trace metal contents of Massif Central rainwater.     

Mercury and methylmercury concentrations and loads in the Cache Creek watershed, California

Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas, a pattern attributable to the lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a significant source of mercury and methylmercury to downstream receiving bodies of water. Much of the mercury in these sediments is the result of deposition over the last 100-150 years by either storm-water runoff, from abandoned mines, or continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas, including the aqueous concentrations of boron, chloride, lithium and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges showed a distinct trend toward enrichment of (18)O compared with meteoric waters, whereas much of the runoff from abandoned mines indicated a stable isotopic pattern more consistent with local meteoric water.     

Atmospheric deposition and migration of artificial radionuclides in Alpine soils (Val Piora, Switzerland) compared to the distribution of selected major and trace elements

Artificial radionuclides (¹³⁷Cs, ⁹⁰Sr, Pu, and ²⁴¹Am) are present in soils because of Nuclear Weapon Tests and accidents in nuclear facilities. Their distribution in soil depth varies according to soil characteristics, their own chemical properties, and their deposition history. For this project, we studied the atmospheric deposition of ¹³⁷Cs, ⁹⁰Sr, Pu, ²⁴¹Am, ²¹⁰Pb, and stable Pb. We compared the distribution of these elements in soil profiles from different soil types from an alpine Valley (Val Piora, Switzerland) with the distribution of selected major and trace elements in the same soils. Our goals were to explain the distribution of the radioisotopes as a function of soil parameters and to identify stable elements with analogous behaviors. We found that Pu and ²⁴¹Am are relatively immobile and accumulate in the topsoil. In all soils, ⁹⁰Sr is more mobile and shows some accumulations at depth into Fe-Al rich horizons. This behavior is also observed for Cu and Zn, indicating that these elements may be used as chemical analogues for the migration of ⁹⁰Sr into the soil.     

REE characteristics and Pb, Sr and Nd isotopic compositions of steel plant emissions

A comprehensive Pb-Sr-Nd isotope and REE tracer study of atmospheric trace metal pollution by a steel plant situated to the north of the urban communities of Strasbourg (France) and Kehl (Germany) has been performed using tree barks as biomonitors. The 206Pb/207Pb and 208Pb/207Pb isotopic ratios of the steel plant's filter dust are similar to values found in dust of waste incinerators. The 87Sr/86Sr ratio is similar to present-day ratios of Phanerozoic or Precambrian granitic rocks. The 143Nd/144Nd isotopic composition is very low and corresponds to an (Nd) value of -17.5. Such a low value is characteristic of old Precambrian granitic rocks and banded iron formations. Thus, this low (Nd) value might point to the origin of the iron necessary for the steel production. The fact, that this isotopic composition does not occur in crustal rocks of Western Central Europe makes the Nd isotope ratio a powerful tool to trace steel plants atmospheric emissions. The rare earth element (REE) distribution pattern of the steel plant's filter dust shows very specific fractionations like La and Nd enrichments which are traceable in tree barks over a distance of 4 km. The Pb, Sr and Nd isotope ratios not only enable the steel plant's emissions to be traced in a north-easterly direction, along the principal wind pathway but also enables the interference of this emission at 4 km NE from the steel plant with another atmospheric component originating from the Strasbourg Rhine harbour to be identified.     

福建船场铅锌多金属矿区花岗斑岩地球化学特征及地质意义

船场铅锌多金属矿区位于福建上杭—云霄金银铜铅锌钨钼成矿带。矿区内花岗斑岩为钙碱性系列,具高硅、高铝、高碱、富钾的特征;花岗斑岩稀土元素总量高,且富轻稀土,并具有明显的负铕异常,稀土元素标准化分布型式为右倾V型,与A型花岗岩具有相似性。花岗斑岩体中Pb、Zn、W、Mo等成矿元素含量,高于中国花岗岩中的平均值的2~6倍。矿区内Pb、Zn等成矿与花岗斑岩有着密切的成因联系,岩浆活动为矿区内Pb、Zn等成矿提供了必要的热源和物源条件。     

Mercury and trace metal partitioning and fluxes in suburban Southwest Ohio watersheds

Many natural watersheds are increasingly affected by changes in land use associated with suburban sprawl and such alterations may influence concentrations, partitioning, and fluxes of toxic trace metals in fluvial ecosystems. We investigated the cycling of mercury (Hg), monomethylmercury, cadmium, copper, lead, nickel, and zinc in three watersheds at the urban fringe of Dayton, Ohio, over a 13-month period. Metal concentrations were related positively to discharge in each stream, with each metal having a high affinity for suspended particles and Hg also having a noticeable association with dissolved organic carbon. Although not observed for the other metals, levels of Hg in river water varied seasonally and among streams. Yields of Hg from two of the catchments were comparable to that predicted for runoff of atmospherically deposited Hg (∼25% of wet atmospheric flux), whereas the third watershed had a significantly greater annual flux associated with greater particle-specific and filtered water Hg concentrations, presumably from a point source. Fluxes of metals other than Hg were similar among each watershed and suggestive of a ubiquitous source, which could be either atmospheric deposition or weathering. Results of this study indicate that, with the exception of Hg being increased in one watershed, processes affecting metal partitioning and loadings are similar among southwest Ohio streams and comparable to other North American rivers that are equally or less impacted by urban development. Relative differences in land use, catchment area, and presence or absence of waste water treatment facilities had little or no detectable effect on most trace metal concentrations and fluxes. This suggests that suburban encroachment on agricultural and undeveloped lands has either similarly or not substantially impacted trace metal cycling in streams at the urban fringe of Dayton and, by extension, other comparable metropolitan areas.     

Critical examination of trace element enrichments and depletions in soils: As, Cr, Cu, Ni, Pb, and Zn in Swiss forest soils

The aim of this study was to obtain an overview of trace element concentrations in Swiss forest soils and to critically assess the measured values with respect to anthropogenic input vs. lithogenic background. Twenty-three sites were selected which represent a broad range of natural forest sites, bedrock material and soil types of Switzerland. At each site, samples were collected from all genetic soil horizons down to a C or B/C horizon. Total concentrations of As, Cr, Cu, Ni, Pb, and Zn in all samples were determined by X-ray fluorescence spectrometry. There were distinct differences in the geological background values estimated from the concentrations measured in the samples from the lowest soil horizon. Background concentrations for Cr and Ni were lowest in granite and gneiss, whereas Pb and Zn were highest in limestone and marl. Enrichment or depletion of the trace elements was assessed using Zr as reference element. Within the same profile, the six trace elements showed completely different enrichment/depletion patterns with depth. The various natural processes and anthropogenic inputs that can lead to these patterns are critically discussed. Based on this critical assessment, pollution of the investigated forest soils was found to be most severe for Pb and Zn and to a somewhat lesser extent for As and Cu, whereas anthropogenic input of Cr and Ni seems to be less important. The data suggest that a critical evaluation of enrichment factors is a better tool to assess soil pollution with trace elements than the use of maximum allowable concentrations (MAC) for topsoil samples. The enrichment factors calculated as described here consider the effects of geological variation on metal abundances whereas the MAC does not. In order to obtain an estimate of soil solution concentrations, water extracts of the samples collected from a subset of 10 soil profiles were analyzed for the same trace elements. Solubility of all elements generally decreased with soil depth. An exception was Cr, Cu, and Ni solubility in the humus layer, which was lower than in the underlying mineral horizon. For all elements, solubility was higher for the collective of soil samples depleted in this element when compared to the samples, in which the element was enriched.     

A chemical and mineralogical reconstruction of Zn-smelter emissions in the Kempen region (Belgium), based on organic pool sediment cores

The atmospheric pollution history of a former Belgian Zn-smelter complex is preserved in organic sediments of a nearby peat bog pool. The stratigraphy of trace metals, Pb-isotope ratios and mineralogy indicate extreme heavy metal pollution in recent sediments. In the pollutant trend, extremes coincide with maxima in 20th century metal production, minima during major war conflicts and the final shutdown of the smelter. Peak pollution concentrations measure up to 4.7 wt.% Zn, 1.1 wt.% Pb and 0.1 wt.% Cd, which correspond to calculated atmospheric deposition rates of 9.0, 1.6 and 0.16 g m(-2) yr(-1), respectively. 206Pb/207Pb isotope ratios show higher values in the polluted interval (1.135-1.162) relative to local geogenic values deeper down-core (1.194-1.215). Within the polluted interval, three significantly different 208Pb/206Pb plateaus are recognized and suggested to indicate changes in the origins of processed ores. Microprobe analyses on sediment thin sections show extensive in situ FeS2 and ZnS precipitation, which suggests that anoxic processes are responsible for the immobilization of the atmospheric metal inputs. The occurrence of oxidized smelter dusts in an independent surface soil sample indicates a rapid diagenetic transformation of metal oxides into sulfides. Morphology and chemical characteristics allow the distinction between smelter related and diagenetic mineral deposits, and give evidence for dust from open-air ore repositories, as well as smelter operation without dust filters.