Effects of pH, alkalinity and bedrock chemistry on metal concentrations of springs in an acidified catchment (Ecker Dam, Harz Mountains, FRG)

Thirty-four springs were sampled on five different source rocks in the upper Ecker watershed of the Northern Harz Mountains (Germany) four times during the course of 1995. The analyses included 41 cations and the major anions. Approximately 90% of the rocks in the upper Ecker watershed are low in basic cations, which inhibit the neutralisation of hydrogen-ion loading. As a consequence, the concentrations of Al, Fe, Mn, Zn, Pb, Y, Ce, As, La, Nd, Cd, Be, Co, Sb, Pr, Gd, Dy, Yb, Er, Sm, U, Tl, Ho and Tb of the Ecker dam water (pH=5.1) exceed those of the nearby Söse Dam water (pH=6.5) by almost one order of magnitude or more. With the exception of the spring waters on gabbro (pH up to 7.7) all waters on the highly siliceous rocks (quartzite, granite and gneiss) are dominated by sulfate anions with a pH range of 4–6. The concentrations of major conservative ions show a progressive increase with decreasing catchment elevation and decreasing average precipitation. Trace elements such as Sr, Be, Zn, Cd, Ba, Y, La, lanthanides, U, Li, Ni, Al, Mn, Co, Cu, Pb, As, Sb and Tl are increased in the low acid neutralizing capacity (ANC_(aq)) spring waters. The behaviours of Sr, Be, Zn, Cd, Ba, Y, La, lanthanides and U resemble that of the major cations. The highest concentrations of Li and Ni are found on quartzite. Al, Mn, Co and Cu exhibit no clear correlation with catchment elevation and one particular bedrock. The concentrations of V and Cr show a distinct increase in high ANC_(aq) spring waters on gabbro. Pb, As, Sb and Tl are characterized by being found in relatively high concentrations on granite at higher altitudes. Pb, As and Sb are affected by contaminated soils. The extreme variability of trace element concentrations of low ANC_(aq) spring waters cannot be explained by the rock data. It is mainly controlled by the topography-dependent weathering rates of the different rock-types and the decreasing dilution with decreasing catchment elevation.     

Analysis of trace elements (heavy metal based) in the surface soils of a desert–loess transitional zone in the south of the Tengger Desert

It is very important to strengthen the research about the heavy metal pollution of soil in vulnerable ecological regions of the south-central arid area of Northwest China for regulating and guiding local industrial and municipal activities and for protecting the environment. In this study, 48 surface soil samples were collected in the desert–loess transitional zone in the south of the Tengger Desert. The distributions of elements (heavy metal based) and the differences between urban and natural soils were analyzed. We observed that As, Pb, Cu, Zn and S were clearly enriched in the Baiyin area, and Ni and Cr were mainly enriched in the Zhongwei area. V, Mn, Ti, Bi, Co and W were enriched in the southeast margin of the Tengger Desert, where there is relatively little human activity. Over the entire study area, Ce, La and Nd were widely distributed across regions whether with strong or weak human activity. Based on the distributions of elements, we suggest that in the desert–loess transitional zone in the south of the Tengger Desert, the distribution and abundances of element As, Pb, Cu, Zn, S, Ni and Cr are strongly related to the human activities in the area, but the elements V, Mn, Ti, Bi, Co, W, Ce, La and Nd are derived mainly from natural sources.     

Release of heavy metals during weathering of the Lower Cambrian Black Shales in western Hunan,China

Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area.     

青海北祁连冷龙岭地区水系沉积物元素地球化学特征及异常圈定

青海冷龙岭地区位于北祁连成矿段的东段,是形成与海相火山岩有关的块状硫化物矿床及岩浆热液型矿床的有利地区,具有良好的找矿潜力。在1∶5万水系沉积物测量成果的基础上,对青海冷龙岭地区Au、Cu、Pb、Zn等17种元素的地球化学特征进行了初步分析,发现本区Ag、Pb、Zn、W、Sn、Bi、Mo、Ba、Cd等元素丰度明显高于青海省及祁连地区水系沉积物的平均丰度值;元素分布特征显示下奥陶统阴沟群除Hg、La、Ce相对贫化外,各元素都呈现不同程度的浓集,加里东期侵入岩中Ag、Cu、Pb、Zn、W、Au、Sn、Bi等元素富集程度较高,海西期正长岩内Ba、La、Ce等元素富集程度较为显著;R型聚类分析和因子分析显示区内的主要成矿元素组合为Cu Pb Ag Mo Ba La Ce,Au具有独立成矿的潜力。结合元素地球化学参数及富集离散特征,认为本区Au、Ag、Cu、Pb、Zn、Mo、La、Ce等元素具有一定的找矿潜力。本次工作共圈定8个综合异常。根据研究区成矿地质背景、异常特征及查证成果,与该区域内浪力克铜矿床和青分岭金矿床的地质地球化学特征对比研究后,优选出干沙河和三道路圈—倒阳河2个成矿远景区。     

Mobility and retention of trace elements in hardpan-cemented cassiterite tailings, north Queensland, Australia

This study reports on the mobility and retention of trace elements in cassiterite tailings at the inactive Jumna mill, tropical north Queensland. Since the 1980s, the uncapped tailings have developed laterally discontinuous Fe-rich hardpans, which are located in the higher parts of gently sloping tailings masses and at the top (<50 cm) of the tailings piles. Hardpan-cemented tailings comprise thin layers (typically ∼0.2–2 mm thick) of HFO (hydrous ferric oxides) and sulfate efflorescences cementing tailings grains. In comparison to the tailings, the hardpan-cemented tailings contain significantly higher median As, Ca, Cd, Co, Cu, Fe, In, Mn, Mo, S_total, Th, U, Y and Zn values. Partial leaching studies of tailings and pond water analyses indicate that wetting and acidification of Fe-cemented tailings removes significant proportions of trace elements into pore and surface waters. Tin shows no mobility due to the presence of weathering-resistant cassiterite (SnO₂) and, As and Pb display limited mobility possibly due to their coprecipitation with jarosite-type phases and HFO materials at the top of the tailings profile. By contrast, the trace elements Cd, Ce, Cu, La, Ni, Pb, U and Zn display the greatest mobility, possibly due to their incorporation in soluble sulfate efflorescences and sorption onto mineral and HFO surfaces. Hence, the Fe-rich hardpans do not protect the sulfidic tailings from further oxidation nor do they cause permanent sequestration of trace elements.     

Statistical assessment of geochemical pattern in overbank sediments of the river Sava,Croatia

Four overbank profiles from the three terraces of different age were sampled in 10 to 20 cm intervals for the bulk content of major and minor (Ca, Mg, Fe, Ti, Al, Na, K and P) and trace (Mo, Cu, Pb, Zn, Ni, Co, Mn, As, U, Th, Sr, Cd, Sb, V, La, Cr, Ba, W, Zr, Ce, Sn, Y, Nb, Ta, Sc, Li, Rb and Hf) elements in the minus 0.125 mm fraction. Univariate statistics together with analysis of variance discriminated between the lower-lying carbonate (CA) population dominantly composed of carbonates and the overlying silicate (SI) population being dominantly of silicate mineralogy. This stratified pattern resulted from the intensive erosive action of melting glaciers exerted on limestones and dolomites in the alpine region, followed by local inputs mainly of silicate composition. Elements exhibiting the greatest between-population variability are Ca and Mg being enriched in the CA population and Fe, Mn, P, Sr, Al, Na, K, Li, Rb, Y, Zr, Ni, Cr and Ti being enriched in the SI population. Anomalously high Hg, Pb and Ba concentrations (maximum values: 6,500±2,860 ppb, 225±13 ppm and 1,519±91 ppm, respectively) in the lowermost part of the profile S7, which is nearest to the Croatian-Slovenian border, derive from the mineralized Slovenian catchment area. This profile also contains trimodal frequency distributions of Fe, Mn and P whose highest concentrations coincide with increased values of Zn and Cu which are bimodally distributed. Geochemical patterns of majority of elements in all four profiles consistently reflect the average compositions of the upstream drainage basins.     

Effects of water acidification on element concentrations in natural waters of the Kola North

This study discusses the problem of evolution of water chemistry under the influence of acid loadings from copper–nickel smelters of the Kola mining and smelting company (“KGMK”). The natural waters of the Kola Peninsula are characterized by low contents of biogenic substances and mineral salts owing to low water temperatures and low mass transfer rates at high latitudes. Acid precipitation causes water acidification in regions made up by granite gneisses and sandy rocks. Unlike naturally acidic waters with high humic acid contents, these lakes have high-transparency waters. The results show that Cd, Bi, Se, and Re become involved in the transport fluxes irrespective of a natural or anthropogenic source of acidification. Acidified lakes have higher Zn, Pb, As, Bi, and Sb contents compared to neutral lakes. The high coefficient of aqueous migration of Se, Re, Bi, Sb, Cd, and Sn is indicative of the anthropogenically-induced dispersal of these elements.     

Abundance, Sources and Speciation of Trace Elements in Humus-Rich Streams Affected by Acid Sulphate Soils

The behaviour of trace elements (Al, As, Cd, Co, Cr,Cu, Fe, Mn, Ni, V, Zn) was studied in five humus-richstreams (dissolved organic carbon = 14–40 mg/L)impacted by acid sulphate soils developed in marinesulphide-bearing fine-grained sediments. During heavyrainfalls in autumn, on which the study focusses, themetals Al, Cd, Co, Cu, Mn, Ni and Zn are extensivelyleached from these acidic soils (pH = 2.5–4.5), whileAs, Cr, Fe and V are not leached more strongly fromthis soil type than from areas of till and peat. Aspeciation experiment, based on anion and cationexchange of the stream waters in the field, showedthat (1) the metals Al, Cd, Co, Mn, Ni and Zn aretransported in the streams mainly as inorganiccations, (2) Cu exists mainly in cationic form but isalso to a significant extent associated with dissolvedhumic substances, (3) Fe occurs mainly in the anionicfraction explained by organic coating on colloidal Feoxyhydoxides and (4) the hydrochemistry of As, Cr andV is complex as these elements may exist in severalunquantified anionic fractions and to a minor extentin cationic species/forms. Whereas the proportion ofacid sulphate soils in the catchments had a largeimpact on concentrations levels of several elements inthe stream waters, these soils did not have a largeaffect on the speciation of elements in water.     

Accumulation of potentially toxic elements in sediments in Budi Lagoon,Araucania Region,Chile

The concentrations of Cd, Cu, Mn, Ni, Pb, Fe and Zn were determined in superficial sediments extracted from nine zones of Budi Lagoon, located in the Araucanía Region (Chile). The concentrations of these metals were determined by flame atomic absorption spectroscopy and the method was validated using certified reference material (marine sediment). The concentration ranges found for the trace elements were: Pb < 0.5; Cd < 0.2–3.9; Cu 21.8–61.9; Ni 31.2–59.4; Zn 54.5–94.8 mgkg^?1 (dry weight). The elements that registered the highest concentrations were Mn 285.4–989.8 mgkg^?1 and Fe 4.8–10.6 %. The lagoon cluster analysis of the stations was divided into three groups (Temo station with high Cu and low Mn concentrations, Bolleco, Comué, Allipén and Deume 3 stations presented highest Cd concentration, and another group Botapulli, Río Budi, Deume 2 and Deume 1 stations presented low levels of Cd). The textural characteristics of the sediment were determined (gravel, sand and mud) and the results were correlated with the concentrations of the metals in the various study zones. The sediments of Budi Lagoon presented high levels of Fe and Mn, which are of natural origin and exceed the maximum values recorded by many authors. With respect to the recorded concentrations for Cd, Cu, Ni and Zn, are within the ranges published by other authors in similar works. The Pb element was not detected. The results were subjected to statistical analysis to evaluate the correlations between the content of the elements and obtain the site of sediment.     

Geochemical mapping in northern Honshu,Japan

Geochemical mapping of northern Honshu in the Northeast Japan Arc was carried out using stream sediments at a sampling density of one sample per 130 km². More than 50 elements were determined in 395 stream sediment samples (<0.18 mm fraction). In geochemical maps, areas with especially low concentrations of large ion lithophile elements (LILE), Be and Li widely overlap with the distribution of Quaternary volcanic rocks along the volcanic front. The areas rich in mafic elements are associated with mafic rocks in many cases. On a regional scale, Ni, Cr and Cu contents are higher in the eastern Paleozoic–Mesozoic basement zone, Pb and Tl tend to be higher on the western zones, and Zn and Cd are high in the western back-arc zone. The areas especially rich in Cu, Zn, Cd, Pb, Bi and Tl coincide with the distribution of large mineral deposits. High concentrations related to Kuroko, hydrothermal-vein, and skarn-type deposits are recognized. High values of As and Sb are related to active geothermal areas near volcanoes and ore deposits. Chemical variations of K, Ce, Th and Sn in the stream sediments are concordant with chemical variations in major rocks. The median and mean concentrations for the stream sediments in northern Honshu, showing arc signatures, are lower in Rb, Cs, Th, Li, K, Be, Ta, LREE, Ni, Hg and Sn, and higher in Sc, Ca and Cd relative to the whole area of Japan, largely because of the contribution of Cenozoic island-arc volcanic rocks that are generally poor in incompatible elements. The averaged chemical compositions of the stream sediments for the geologic zones show systematic variations of many elements. The contrasting variations of LREE and Th contents, which are lower in the zones of Cenozoic rocks relative to the zones of pre-Neogene basements, reflect the regional variations in the main rocks, and also reflect the change of geological settings of the studied area from the continental margin to an island arc during the Cenozoic.     

Trace elements in ferromanganese concretions,gibbsite spots,and the surrounding terra rossa overlying dolomite: Their mobilization,redistribution and fractionation

The mobilization, redistribution and fractionation of trace elements during chemical weathering processes have been investigated on a 4.05 m thick terra rossa profile overlying dolomite on the Yunnan-Guizhou Plateau, in Southwest China. In this in situ weathering profile, the ferromanganese concretions and the gibbsite spots coexist in the terra rossa saprolite. The mass-balance evaluation reveals that titanium, Nb and Hf in the terra rossa matrix are conservative elements during chemical weathering compared to Zr. The elements of Li, Sc, V, Cr, Fe, Ga, As, Mo, Cs, Ce, Ta, Tl, Pb and Th in the terra rossa matrix include additions from external sources. Beryllium, Mn, Co, Ni, Cu, Rb, Ba and La are depleted in the shallow parts of the terra rossa profile and enriched in the deep parts. The elements of Zn, Sr, Y, Cd, Sn and U in the terra rossa profile are lost during weathering. Compared to the terra rossa matrix, the ferromanganese concretions are significantly enriched in most trace elements, especially Mn, Co, Cd, Ce, Tl and Pb. In contrast, the gibbsite spots are depleted in all trace elements, except for U. The results regarding specific inter-element relationships indicate that most trace elements have different inter-element relationships in the ferromanganese concretions, the gibbsite spots and the terra rossa matrix. This suggests that the behavior of many trace elements during mobilization and redistribution differs from their behavior during incorporation into secondary mineral phases, especially the Mn and Fe oxides and/or oxyhydroxides in the ferromanganese concretions. It is worthy to note that the fractionation between Ce and Mn occurs under intensive chemical weathering conditions. Correspondingly, beryllium exhibits a similar geochemical behavior as that of rare earth elements (except for Ce) and Y during surface weathering.     

Tailings dam seepage at the rehabilitated Mary Kathleen uranium mine,Australia

This study reports on the seepage of metals, metalloids and radionuclides from the Mary Kathleen uranium mill tailings repository. Since rehabilitation in the 1980s, the capped tailings have developed a stratified hydrochemistry, with acid (pH 3.7), saline, metal-rich (Fe, Mn, Ni, U ± As, Pb, Zn), oxygenated (1.05 mg L⁻¹ DO), radioactive waters in the upper tailings pile and near-neutral pH (pH 7.57), metal-poor, reduced (0.08 mg L⁻¹ DO) waters at depth. Seepage (∼0.5 L s⁻¹) of acid (pH 5.5), metal-rich (Fe, Mn ± Ni, U, Zn), radioactive (U-235, U-238, Ra-226, Ra-228, Ac-227) waters occurs from the base of the tailings dam retaining wall into the former evaporation pond and local drainage system. Oxygenation of the seepage waters causes the precipitation of Fe and coprecipitation and adsorption of other metals (U, Y), metalloids (As), rare earth elements (Ce, La) and radionuclides (U-235, U-238). By contrast, alkalis and alkaline–earth elements (Ca, K, Mg, Na, Sr), Mn, sulfate and to some degree metals (U, Zn, Ni), rare earth elements (Ce, La) and radionuclides (U-235, U-238, Ra-226, Ra-228) remain in solution until pH neutralisation and evaporation lead to their precipitation in efflorescences and sulfate-rich evaporative sediments. While the release of contaminant loads from the waste repository through seepage is insignificant (e.g. ∼5 kg of U per year), surface waters downstream of the tailings impoundment possess TDS, U and SO₄ concentrations that exceed Australian water quality guideline values in livestock drinking water. Thus, in areas with a semi-arid climate, even insignificant load releases of contaminants from capped tailings repositories can still cause the deterioration of water quality in ephemeral creek systems.     

Trace metals (Cd,Cu, Ni,and Zn) and nutrients in coastal waters adjacent to San Francisco Bay,California

Samples collected in December 1990 and July 1991 show that dissolved Cd, Cu, Ni, and Zn distributions in the Gulf of the Farallones are dominated by mixing of two end-members: (1) metal-enriched San Francisco Bay water and (2) offshore California Current water. The range of dissolved metal concentrations observed is 0.2–0.9 nmol kg^?1 for Cd, 1–20 nmol kg^?1 for Cu, 4–16 nmol kg^?1 for Ni, and 0.2–20 nmol kg^?1 for Zn. Effective concentrations in fresh water discharged into San Francisco Bay during 1990–1991 (estimated by extrapolation to zero salinity) are 740–860 μmol kg^?1 for silicate, 21–44 μmol kg^?1 for phosphate, 10–15 nmol kg^?1 for Cd, 210–450 nmol kg^?1 for Cu, 210–270 nmol kg^?1 for Ni, and 190–390 nmol kg^?1 for Zn. Comparison with effective trace metal and nutrient concentrations for freshwater discharge reported by Flegal et al. (1991) shows that input of these constituents to the northern reaches of San Francisco Bay accounts for only a fraction of the input to Gulf of the Farallones from the estuary system as a whole. The nutrient and trace metal composition of shelf water outside a 30-km radius from the mouth of the estuary closely resembles that of California Current water further offshore. In contrast to coastal waters elsewhere, there is little evidence of Cd, Cu, Ni, and Zn input by sediment diagenesis in continental shelf waters of California.     

中国多金属结核开辟区沉积物中微量元素地球化学特征

分析了中国多金属结核开辟区沉积物中Ba、Ce、Co、Cr、Cu、Mo、Ni、Sr、V、Y和Zn等11个微量元素的含量。研究表明，开辟区沉积物中微量元素在不同沉积单元中的分布特征存在明显差异，反映了地质历史上沉积环境的不同。沉积物中的Zn、Ni和Mn具有共同来源，反映铁锰氧化物、氢氧化物对这些元素的吸附控制作用；Sr、Ba以及Ce和Y等元素在东区主要与岩源碎屑有关，而西区则主要来自生物碎屑；Cu具有多种来源，东区主要与生物组分和岩源碎屑有关，西区则主要与自生铁锰氧化物的吸附有关。而通常认为与有机物有关的Cr、V等元素在研究区内则主要来自岩源碎屑。     

Geochemistry of rare-earth elements in thermal waters of Uzon-Geyzernaya hydrothermal system (Kamchatka)

Precisional analyses of the abundances of La, Ce, and major elements in thermal waters and rocks of the Uzon-Geyzernaya volcanotectonic depression, supplemented by published data on a number of modern high-temperature hydrothermal systems of Kamchatka and two other areas of the world, allowed defining genetically important patterns of rare-earth elements (REE) distribution. The La and Ce abundances positively correlate with silica contents both in fresh igneous rocks of the study areas and in the products formed by hydrothermal processes.All studied hydrothermal clays are enriched in La and Ce. The general enrichment trend is similar to the pattern of positive correlation between the La and Ce abundances. Geothermal waters display a strong relationship between REE enrichment and pH. Enhanced REE enrichment trend is observed in thermal waters with abundant SO₄^2 ? and K. The REE versus Cl and B diagrams show two individual fields reflecting the level of acidity-alkalinity of thermal waters. These data demonstrate that La and Ce concentrations in the products of modern hydrothermal systems (in fluids and secondary mineral phases) are governed by wallrock composition, anionic water composition, and pH/Eh-dependent adsorption processes.     

The natural attenuation of two acidic effluents in Tharsis and La Zarza-Perrunal mines (Iberian Pyrite Belt, Huelva, Spain)

The geochemical evolution of two acid mine effluents in Tharsis and La Zarza-Perrunal mines (Iberian Pyrite Belt, Huelva, Spain) has been investigated. In origin, these waters present a low pH (2.2 and 3.1) and high concentrations of dissolved sulphate and metals (Fe, Al, Mn, Cu, Zn, As, Cd, Co, Cr, Ni). However, the natural evolution of these acidic waters (which includes the bacterial oxidation of Fe(II) and the subsequent precipitation of Fe(III) minerals) represents an efficient mechanism of attenuation. This self-mitigating process is evidenced by the formation of schwertmannite, which retains most of the iron load and, by sorption, toxic trace elements like As. The later mixing with pristine waters rises the pH and favours the total precipitation of Fe(III) at pH 3.5 and, subsequently, Al compounds at pH 4.5, along with the sorption of trace metals (Mn, Zn, Cu, Cd, Co, Ni) until chemical equilibrium at circumneutral conditions is achieved.     

Geochemistry of the Kola River, northwestern Russia

The Kola River in the northern part of the Kola Peninsula, northwestern Russia, flows into the Barents Sea via the Kola Bay. The river is a unique place for reproduction of salmon and an important source of drinking water for more than 500,000 people in Murmansk and the surrounding municipalities. To evaluate the environmental status of the Kola River water, sampling of the dissolved (<0.22 μm) and suspended (>0.22 μm) phases was performed at 12 sites along the Kola River and its tributaries during 2001 and 2002. Major (Ca, K, Mg, Na, S, Si, HCO₃ and Cl) and trace (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sr, Ti, and Zn) elements, total and particulate organic C (TOC and POC), N and P were analysed. Comparison with the boreal pristine Kalix River, Northern Sweden, shows that, except for Na, Cl, Al, Cu and Ni, which exceed the concentrations in the Kalix River by as much as 2–3 times, the levels of other major and trace elements are close to or even below the levels in the Kalix River. However, the results also demonstrate that pollutants from the three major sources: (1) the Cu–Ni smelter in Monchegorsk, (2) the open-pit Fe mine and ore concentration plant in Olenegorsk, and (3) the Varlamov, the Medveziy and the Zemlanoy creeks, draining the area of the large agricultural enterprises in the lower part of the watershed, have a major influence on the water quality of the Kola River.     

Ground-water geochemistry in the abitibi volcanic belt of quebec

Large sections of the Abitibi volcanic belt of Archean age are covered by thick glacial and glacio-lacustrine overburden. To increase our knowledge of the geology and the economic potential of the basement, approximately 5000 ground-water samples were collected from wells, springs and drill holes over an area of about 20 000 km². Samples were collected at intervals varying from 150 to 500 m in settled areas. They were analysed for: Cu, Zn, Pb, Ni, Co, Cd, Cr, Mn, Fe, Mo, Hg, As, U, Na, K, Ca, Mg, Li, F, and Cl⁻ and pH.Several types of regional and local geochemical patterns were identified. However, since the apparent dispersion distance of trace elements from a point source is usually less than 1 km in ground waters, the local zones of geochemical activity having an area less than 15 km² are considered of greatest interest for exploration. The large regional patterns and geochemical complexes which consist of clusters of grouped, overlapping, and superimposed regional and local patterns are presumed to be related to particular geological or metallogenic contexts.The elements with the highest frequency of occurrence in the 240 identified local zones of geochemical activity are As, Ni and U which occur in more than 30% of these zones; they are closely followed by the groups Co, Cu, Mo and Zn, Hg, Pb, F⁻ which occur respectively in more than 25% and 20% of the zones. Element associations in these zones can be broken down into three major groups: the trace metals (Cu, Zn, Pb, Co, Cd, Mo), the major and associated elements (Na, K, Ca, Mg, Li, F⁻, Cl⁻) and the elements As, U and Ni which occur with elements of either of the first two groups.Ground-water samples were also collected in 21 mines. The results of this study suggest that the best indicator elements for base metal deposits are As, Mo and F, whereas As, Ni, F⁻ or Cl⁻ and Mn are the best indicators of gold deposits.The results of the ground-water survey have identified numerous new areas to explore. Anomalous concentrations of at least two of the best indicators occur in more than 33% of the 240 local zones of geochemical activity.     

Assessment of the Ecological State of the Arctic Freshwater System Based on Concentrations of Heavy Metals in the Bottom Sediments

The ecological state of the Inari Lake–Pasvik River system, the largest in northern Fennoscandia (in the near-border territories of Russia, Norway, and Finland) was assessed based on studying concentrations of heavy metals (HM) in the bottom sediments (BS). The water body (Kuetsjarvi Lake) contaminated with liquid wastes from the Pechenganickel smelter contains the highest HM (Ni, Cu, Co, Zn, Pb, Cd, Hg, and As) concentrations in the uppermost BS layers. In water bodies down and up the Pasvik River of the discharge site of waste waters from the smelter, the uppermost BS layers do not contain elevated concentrations of contaminating HM typical of the area (Ni, Cu, Co, Zn) but do contain higher concentrations of chalcophile elements (Pb, Cd, Hg, and As), which come mostly from trans-border sources. In the lakes receiving domestic wastes, phosphorus concentrations increase up the vertical section of the BS, which may suggest the development of eutrophication processes. They result in reducing conditions in the bottom waters and uppermost BS layers and, consequently, the transfer of ionic species of elements susceptible to variations in the redox potential from BS to waters. This process leads to depletion of the uppermost BS layers, first of all, in Fe and Mn and also in HM adsorbed on the surface of Fe and Mn oxides and hydroxides. In the water bodies that have preserved their oligotrophic nature, the uppermost BS layers were determined to accumulate Fe and Mn, whose concentrations are up to 50 times higher than the Earth’s crust average and the background values. Quantitative parameters of the factors and degrees of contamination are determined, as also are the ecological risk indexes for the contamination of the water bodies with HM, using the L. Håkanson method adapted to the regional conditions. The nonessential metals Hg and Cd, which are the most toxic and dangerous for hydrobionts, are determined to be the most ecologically hazardous in all of the water bodies. Nickel is a highly ecologically hazardous element in a single water body: Kuetsjarvi Lake. In all other water bodies of the Inari Lake–Pasvik River system, elements emitted and discharged by the smelter (Ni, Cu, Co, Pb, and As) are moderately and low ecologically hazardous for the aquatic systems.     

Distribution of heavy metals in the clastic fine-grained sediments of Gavkhuni playa lake (Southeast of Isfahan,Iran)

The sedimentary basin of Gavkhuni playa lake includes two sedimentary environments of delta and playa lake. These environments consist of mud, sand and salt flats. There are potentials for concentration of heavy metals in the fine-grained sediments (silt and clay) of the playa due to existence of Pb/Zn ore deposits, industrial and agricultural regions in the water catchment of Zayandehrud River terminating to this area. In order to study the concentration of heavy metals and the controlling factors on their distribution in the fine-grained sediments, 13 samples were taken from the muddy facies and concentration of the heavy metals were determined. The results showed that the heavy metal concentrations range in the sediments (in ppm) are Mn (395.5–1,040), Sr (100.4–725.76), Pb (14.66–91.06), Zn (23.59–80.9), Ni (37–73.66), Cu (13.83–29.83), Co (5.73–13.78), Ag (3.03–4.76) and Cd (2.3–5.5) in their order of abundances. The concentration of Ag is noticeable in the sediments relative to the average concentration of this element in mud sediments. The amounts of Pb and Zn are relatively high in all the samples in comparison with the other elements. The concentration of Ni is relatively high in the oxidized samples. The distribution of Pb is directly related to organic matter content of the sediments. The concentrations of Zn, Sr, Cu, Co and Cd in the samples of the playa are lower than those in the delta. The amount of illite is another factor influencing Zn and Pb concentrations. Sr is more concentrated in the sediments with the high content of calcium carbonate. The distribution pattern of Cu, Co, Pb and Mn resembles to that of the clay content of the sediments. The clay content shows positive correlations with Co, Cu and Mn concentrations and negative correlation with Ag. The Sr and Ag concentrations are positively correlated with the amount of CaCO₃. The amounts of Co, Cu, Ni and Mn show negative correlations with the calcium carbonate content. Pb and Co are noticeably correlated with Mn.