Assessment of mercury contamination and human exposure associated with coastal disposal of waste from a cinnabar mining operation, Palawan, Philippines

 An integrated geochemical and toxicological assessment of environmental mercury contamination and attendant human exposure in Honda Bay, Palawan was undertaken in 1995 following a nationally reported pollution scare centered on a coastal jetty, Sitio Honda Bay, constructed using approximately 1 million tons of tailings and beneficiation waste from a cinnabar mine. Mercury (Hg) data for marine and fluvial sediments, fish tissues and human hair indicate that the toxicological hazard is considerably lower than initially reported by state environment and health officials. Typical Hg concentrations in surficial Honda Bay sediments were found to lie within the global background range (<60 μg/kg). Downcore profiles provide no evidence of enhanced Hg fluxes coincident with the onset of mining and/or coastal tailings disposal. The mean and median Hg concentrations recorded in tissues of six species of Honda Bay fish are compliant with thresholds established by the US Environmental Protection Agency (US-EPA) for marketable stocks. Earlier reports of 'Minamata range' Hg concentrations in fish and shellfish from Honda Bay remain unsubstantiated. Geochemical analyses of samples of the Sitio Honda Bay substrate have confirmed the prevalence of solid-phase Hg concentrations to ca. 340 mg/kg. The speciation of Hg is, however, dominated by secondary oxides of low bioavailability. The mean Hg concentration in hair from Sitio Honda Bay residents (4.41 mg/kg) was found to be statistically analogous to that for a neighbouring coastal community unimpacted by the coastal disposal of mine waste. A negligible residential exposure factor is thus inferred for the former. Relatively high hair Hg burdens prevail throughout the coastal Honda Bay population, consistent with significant methyl Hg ingestion through daily fish consumption. The data presented provide no environmental or toxicological justification for immediate remedial action. Received: 14 May 1998/Accepted: 1 September 1998     

The Hg geochemistry of a geothermal stream, Steamboat Creek, Nevada: natural vs. anthropogenic influences

 A series of water samples from Steamboat Creek, Nevada, was analyzed for total mercury concentrations. Concentrations from these waters were 40 to 60 times higher than the pristine mountain streams entering the creek. The major source of the mercury entering Steamboat Creek is probably from gold/silver processing that took place in the 1860s. Received: 10 March 1997 · Accepted: 2 September 1997     

Mercury mobility at the Carson River Superfund Site, west-central Nevada, USA: Interpretation of mercury speciation data in mill tailings, soils, and sediments

The Carson River Superfund Site in west-central Nevada is an area of Hg-contaminated soil, sediment, water, air, and biola resulting from the amalgamation milling of Ag-Au ores of the Comstock lode worked approximately a century ago. In order to develop an understanding of the behavior, transport, and fate of Hg at this site, a technique was developed to estimate the proportions of total, elemental, exchangeable, organic, and sulfide Hg in soils, sediments, and tailings.Results of this analysis performed on active Carson River sediments indicate that Hg is selectively dissolved out of Hg-Au amalgam particles and subsequently adsorbed to fine-grained sediments which are then deposited in downstream, low-energy reaches of the Carson River and Labontan Reservoir. In the relatively more-reducing environment of the reservoir Hg appears to be converted, in large part, to relatively-insoluble HgS.The original elemental form of Hg released to the environment is the chemical form which is still dominant in most highly-contaminated soils, sediments, and tailings. Deeper, more-reducing soil horizons, however, appear to fix a significant portion of the Hg as HgS, analogous to the Lahontan Reservoir example described above. This fixation as HgS is documented to be largely limited to higher-sulfur areas where sulfide minerals from the Comstock ores increase the total sulfur concentrations of contaminated soils, sediments, and tailings.     

Role of monsoon rain on concentrations and dispersion patterns of metal pollutants in sediments and soils of the Ganga Plain, India

 Monsoon rain causes large scale sediment-water movement and reworking of sediments of the Ganga Plain which is one of the largest fluvial systems on Earth. Geomorphology and drainage type combined with sedimentation processes play a substantial role on dispersion and transport patterns of metals bound to sediments and soils. The study area of Kanpur-Unnao industrial region in the Ganga Plain has been divided into five independent geochemical domains on the basis of sediment-geomorphic, hydrological and geochemical characters. The monsoon hydrography and physico-chemical parameters (pH, conductivity) of the river and urban drain waters play a prominent role in regulating the concentrations and behaviour of the metals in the aquatic system of the Ganga Plain. Values of pH and specific electrical conductivity of the river water of the study area decrease whereas those of the urban drain water increase in post-monsoon period. The monsoon rain reduces the contents of Co, C-org, Cr, Fe and Ni and enhances the contents of Cd, Sn and Zn in sediments of post-monsoon period. In soils, it reduces the contents of Al, Co, Fe, Mn and Ni and enhances the contents of Cd, Sn and Zn in the post-monsoon period. These changes in concentrations vary from metal to metal and from one geochemical domain to the other. An increase in the concentrations of few metals in the soils from pre- to post-monsoon periods indicates that these metals were mobilized from the overflooding of metal rich waste-water onto the fields during high water stage and also by reworking of the soils through sheet floods during the monsoon time. Despite the changes in concentrations, metal dispersion patterns in each domain remain similar both in pre- and post-monsoon periods which indicate that the geochemical and sediment-geomorphic processes operating for the metal dispersion and mobilization in sediments are persistent even after large scale sediment-water movement and reworking of the sediments during the monsoon period. Received: 4 May 1998 · Accepted: 20 October 1998     

Water quality in pit lakes in disseminated gold deposits compared to two natural, terminal lakes in Nevada

 Within the next 10–15 years, over 35 mines in Nevada will have a lake in their open pit mines after dewatering and cessation of mining. Of the ten past or existing pit lakes at eight different gold mines for which temporal data are available, most had near neutral pH, yet most had at least one constituent (e.g., As, SO₄, TDS) that exceeded drinking water standards for at least one sampling event. Most samples from pit lakes had TDS exceeding drinking water standards, but lower than that in the natural Pyramid (TDS≈5,500 mg/l) and Walker (TDS≈14,000 mg/l) Lakes. In the past century, salinity increased in both natural, terminal lakes, in part due to irrigation withdrawals and evapoconcentration. The salinity in the pit lakes may also increase through time via evapoconcentration. However, water balance models indicate that up to 132% (Walker Lake) of the total yearly inflow evaporates from the terminal lakes, whereas steady-state may be reached in the pit lakes modelled, where evaporative losses account for only ≈6% of the total pit lake volume annually and ≈100% of the net inflow (groundwater inflow minus outflow, precipitation and runoff into the lake). The effects of evapoconcentration are expected to be less significant at most pit lakes than at the natural, terminal lakes because (1) evaporation rates are lower at many pit lakes because they are located at higher elevations than the terminal lakes, and (2) the surface area to depth ratio of the pit lakes is >1000 times smaller than that of the terminal lakes. Received: 1 March 1999 · Accepted: 13 April 1999     

Water quality assessment in Akpabuyo, Cross River basin, South-Eastern Nigeria

 A baseline study involving analyses of surface and subsurface water samples from the Akpabuyo area was carried out in order to assess their suitability for drinking, domestic and agricultural purposes. Study results show that the waters are acidic (3.41≤pH≤6.28), soft (hardness 2.09–10.68 mg/l as CaCO₃), fresh (conductivity <1400 μs/cm) and characterised by low sodium adsorption ratio, SAR (0.08–0.59). In addition, the mean values of the major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) and anions (SO₄ ^2–, Cl^–, HCO₃ ^–) are all within the World Health Organisation (WHO) standards. Taking all this into consideration (except pH), the waters may be regarded as excellent for drinking, domestic and agricultural purposes. On the basis of regression equations, the major cations (K, Na, Ca, Mg) correlate well with conductivity. Finally, results also show that four chemical facies are delineated. These include Ca-Cl, Na-Cl, Ca-SO₄ and Ca-HCO₃. Received: 19 June 1996 / Accepted: 15 April 1997     

The role of fluvial geomorphic processes in the dispersal of heavy metals from mine sites

It is not uncommon for more than 90% of the total metal load in rivers to be transported in the solid phase, either sorbed onto particle surfaces and coatings, or incorporated into mineral grains. Fluvial geomorphic processes are therefore of fundamental importance in the transport and fate of heavy metals derived from mine sites. In this paper, the role of physical processes in the dispersal of heavy metals in river systems are reviewed for channels that have (1) remained relatively unchanged in terms of process and form following the introduction of mine wastes, and (2) exhibited a significant metamorphosis in channel form in response to the influx of mining and milling debris. In general, all processes responsible for the variations in metal concentrations within sediments moving through stable channels also operate in channels undergoing metamorphosis. However, downstream, lateral, and vertical patterns in metal values tend to be more complex where channel transformations have occurred. This complexity results, in part, because temporal and spatial changes in the types, rates, and magnitudes of erosional and depositional processes lead to highly variable stratigraphic sequences of post-mining age, and because greater quantities of contaminated debris is stored along the channel margins where it can be eroded and sporadically redistributed during times of flood.     

Detrital transport of metals by glaciers, an example from the Pinchi Mine, central British Columbia

 Abundant cinnabar (HgS) mineralization is associated with the Pinchi Fault in central British Columbia. Two formerly producing mercury mines have been developed on this fault: Pinchi and Bralorne Takla. The mercury content of till (a sediment type directly deposited by glaciers) in the area of this fault is primarily controlled by the occurrence of cinnabar mineralization in bedrock and the direction of ice flow. Cinnabar-bearing bedrock was eroded by glaciers, transported in the direction of ice flow, and deposited "down-ice" from its source. An example of such a dispersal train is documented for the Pinchi Mine area where mercury ore was transported over a distance of 12 km, as measured in the clay-sized fraction (< 0.002 mm) of till, and could have been transported over 24 km according to heavy mineral concentrates (specific gravity >3.3) of this same sediment. Antimony, chromium, and nickel dispersal trains were also detected in the region. These data indicate that natural glacial processes can result in the "mobilization" of metals in the surficial environment, a factor which has to be considered at mine sites in glaciated terrain, where mine reclamation and remediation measures are now required. Received: 31 October 1996 · Accepted: 27 May 1997     

Distribution and fractionation of heavy metals in the surface sediments of the Ganges- Brahmaputra-Meghna river system in the Bengal basin

 The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentation in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is ≤1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (I_geo) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals. The Bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution. Received: 21 July 1997 · Accepted: 13 October 1997     

Hydrologic controls on water chemistry and mercury biotransformation in a closed river system: The Carson River,Nevada

The Carson River flows in a closed basin system and the total flow of the river water decreases downstream due to both evaporation and consumptive uses. This river system is fed primarily by snow pack in the Sierra Nevada during the winter, which flows down gradient following melting in spring and summer. Water loss through evaporation in the Carson River results in a downstream buildup of conservative elements such as Cl⁻ and certain oxyanion forming elements including Se, Mo and W, which are known to interfere with the transformation of Hg within the S cycle. In addition to these naturally occurring hydrologic processes and the resulting affects on water chemistry, the Carson River Basin has been historically impacted by Au and Ag mining that used Hg amalgamation techniques. Contamination of Hg in the Carson River system is now well documented and published Hg concentrations in different environmental compartments are extremely high. In this study, hydrologically driven changes in water chemistry of the river system and the resulting effects on Hg cycling were examined. Results show that periods of low water flow correspond to high water pH (up to 8.3), relatively high concentrations of oxyanion forming elements (e.g., As, Se, Mo and W), and low Hg methylation potential in sediment. In contrast, periods of high flow bring about dilution, which results in lower pH (∼7), lower concentrations of oxyanion forming elements, but higher Hg methylation potential. Overall, changes in flow regimes likely affect rates of methyl-Hg (MeHg) production through a combination of factors such as high pH, which favors MeHg demethylation, and the occurrence of relatively high concentrations of Group VI oxyanions that could interfere with microbial SO₄ reduction and MeHg production.     

Groundwater resources of the middle and upper Odra River basin, southwestern Poland

 The total amount of groundwater resources in the middle and upper Odra River basin is 5200×10³ m³/d, or about 7.7% of the disposable groundwater resources of Poland. The average modulus of groundwater resources is about 1.4 L/s/km². Of the 180 'Major Groundwater Basins' (MGWB) in Poland, 43 are partly or totally located within the study area. The MGWB in southwestern Poland have an average modulus of groundwater resources about 2.28 L/s/km² and thus have abundant water resources in comparison to MGWB from other parts of the country. Several types of mineral waters occur in the middle and upper Odra River basin. These waters are concentrated especially in the Sudety Mountains. Carbon-dioxide waters, with yields of 414 m³/h, are the most widespread of Sudetic mineral waters. The fresh waters of the crystalline basement have a low mineralization, commonly less than 100 mg/L; they are a HCO₃–Ca–Mg or SO₄–Ca–Mg type of water. Various hydrochemical compositions characterize the groundwater in sedimentary rocks. The shallow aquifers are under risk of atmospheric pollution and anthropogenic effects. To prevent the degradation of groundwater resources in the middle and upper Odra River basin, Critical Protection Areas have been designated within the MGWB. Received, January 1995 Revised, May 1996, August 1997 Accepted, August 1997     

Contamination of two Oregon reservoirs by cinnabar mining and mercury amalgamation

 Two reservoirs in western Oregon contain mercury-contaminated sediment and fish as a result of historic mercury mining in the Cottage Grove Lake watershed and mercury amalgamation used in gold mining in the Dorena Lake watershed. On average, sediment in Cottage Grove Lake contains ten times as much mercury as sediment from Dorena Lake (2.720 versus 0.242 ppm). Mercury content in Cottage Grove Lake sediment shows a sharp initial decrease and leveling off with time that reflects the end of the major cinnabar mining phase; deposition of other heavy metals appears to be linked to the clay content of sediment. Mercury input to Dorena Lake has remained fairly constant with time, but small increases in mercury are associated with the deposits of large floods. Copper, lead, and zinc input to Dorena Lake exhibits a marked decrease and leveling off related to the end of commercial mining for these metals. Received: 12 October 1999 · Accepted: 22 March 2000     

Groundwater quality in the Niva River basin, Chittoor district, Andhra Pradesh, India

 This study was made to assess the groundwater quality in relation to agricultural and domestic uses in a part of the Peninsular Archean granite and gneissic complex of India. Water samples were collected from the existing wells in the Niva River basin, Chittoor district, Andhra Pradesh, India and analysed for major ions. The analytical data, processed and interpreted acoording to the WHO standards, reveal that, in general, the groundwater is suitable for both agricultural and domestic uses, exept in a few locations. High concentration of nitrates were observed in some of the wells (both agricultural and domestic) that are affected by the impact of industrial effluents. Multiple regression analysis was performed and used as a positive predictive tool in understanding the chemistry of the groundwater. Received: 2 May 1996 / Accepted: 14 October 1996     

Effects of quarry mining and of other environmental impacts in the mountainous Chicam-Toctina drainage basin (Córdoba, Argentina)

 The environmental conditions prevailing in the Chicam-Toctina drainage system (approx. 138 km² in Córdoba, Argentina) are considered representative of a number of catchments in Argentina's Sierras Pampeanas Range. Two groups of ions reflect the sources of dissolved species in the catchment: a) a group (Cl^–, SO^2– ₄, and Na⁺) which recognizes natural and anthropogenic sources, and which exhibits significant correlations with N^– ₃ and NO^– ₂, and b) another group of components (Ca²⁺, Mg²⁺, and HCO^– ₃) which is clearly controlled by carbonate rocks and their waste rock products. In the headwaters, stockpiled marble quarry mining wastes provide a more open system to CO₂ gaseous exchange than the outcropping rocks, thus promoting the increase of carbonate dissolution (up to 4.88 g km^–2 s^–1 during the rainy season). This specific yield was 20% higher than the amount estimated for an area with fewer extended mining activities. The dissolved load delivered by the upper reaches is subjected in the lower drainage area to various processes, mainly controlled by the presence of the city of Alta Gracia (approx. 40,000 inhabitants). In the dry season, due to nutrient inputs supplied by the city, photosynthetic activity plays a major role controlling stream pH. Hence, the high values of calcite saturation indexes and the increase of CaCO₃ concentration in bed sediments can be explained by calcite precipitation. Such a process could be accompanied by the coprecipitation on calcium carbonate of low solubility heavy metal carbonates. Received : 17 January 1997 · Accepted : 31 March 1997     

The spa Deutsch-Altenburg and the hydrogeology of the Vienna basin (Austria)

 Some years ago the thermal water wells of the spa Deutsch-Altenburg were considered the result of a local water circulation. Extensive measurements of the water chemistry, trace elements, and environmental isotopes combined with drillings in the river bed of the Danube resulted in the indication of a key position of the mineral thermal wells of Deutsch-Altenburg for the groundwater circulation in the entire Vienna basin. The proof of this fact demanded the inclusion of the complicated geological position of the basin into the argumentation. The historical background of Bad Deutsch-Altenburg is the Roman municipium Carnuntum. During the reign of the Roman emperor Marc Aurel (161-180 A.C.) Carnuntum became the largest Roman municipium northeast of Rome with about 50 000 inhabitants covering the areas of present-day villages Petronell and Deutsch-Altenburg due to its strategic and trade position. The town was totally destroyed during the era of "migration of nations." The land surface was farmland or meadows. The first document concerning the thermal water of Deutsch-Altenburg is an expertise of the medical faculty of the University of Vienna (1548). During the siege of Vienna by the Turkish army under Kara Mustafa (1683–84) Deutsch-Altenburg was again, destroyed. It was only at the end of the 19th century that the modern installation of the spa began. The healing thermal water with the highest content of sulfur in Austria made Deutsch-Altenburg one of the most well-known spas in the country. The archaeological excavation of Carnuntum is the largest in Austria. Received: 6 October 1995 · Accepted: 13 November 1995     

Nutrient (P, N) dynamics in the southwestern Kattegat, Scandinavia: sedimentation and resuspension effects

 The yearly nutrient supply from land and atmosphere to the study area in SW Kattegat is 10 900 tons of N and 365 tons of P. This is only few percent of the supply from adjacent marine areas, as the yearly transport through the study area is 218 000 tons of N and 18 250 tons of P. Yearly net deposition makes up 1340 tons of N (on average 2.5 g m^–2 yr^–1) and 477 ton of P (on average 0.9 g m^–2 yr^–1). Shallow-water parts of the study area have no net deposition because of frequent (>35% of the year) resuspension. Resuspension frequency in deep water is <1% of the year. Resuspension rates, as averages for the study area, are 10–17 times higher than net deposition rates. Because of resuspension, shallow-water sediments are coarse lag deposits with small amounts of organic matter (1.1%) and nutrients (0.04% N and 0.02% P). Deep-water sediments, in contrast, are fine grained with high levels of organic matter (11.7%) and nutrients (0.43% N and 0.15% P). Laboratory studies showed that resuspension changes the diffusive sediment water fluxes of nutrients, oxygen consumption, and penetration into the sediment. Fluxes of dissolved reactive phosphate from sediment to water after resuspension were negative in organic-rich sediments (13.2% organic matter) with low porosity (56) and close to zero in coarse sediments with a low organic matter content (2.3%) and high porosity (73). Fluxes of inorganic N after resuspension were reduced to 70% and 0–20% in relation to the rates before resuspension, respectively. Received: 10 July 1995 · Accepted: 19 January 1996     

Heavy metal pollution in freshly deposited sediments of the Yamuna River (the Ganges River tributary): a case study from Delhi and Agra urban centres, India

 The Yamuna River sediments, collected from Delhi and Agra urban centres, were analysed for concentration and distribution of nine heavy metals by means of atomic adsorption spectrometry. Total metal contents varied in the following ranges (in mg/kg): Cr (157–817), Mn (515–1015), Fe (28,700–45,300), Co(11.7–28.4), Ni (40–538), Cu (40–1204), Zn (107–1974), Pb (22–856) and Cd (0.50–114.8). The degree of metal enrichment was compared with the average shale concentration and shows exceptionally high values for Cr, Ni, Cu, Zn, Pb and Cd in both urban centres. In the total heavy metal concentration, anthropogenic input contains 70% Cr, 74% Cu, 59% Zn, 46% Pb, 90% Cd in Delhi and 61% Cr, 23% Ni, 71% Cu, 72% Zn, 63% Pb, 94% Cd in Agra. A significant correlation was observed between increasing Cr, Ni, Zn, and Cu concentrations with increasing total sediment carbon and total sediment sulfur content. Based on the Müller's geoaccumulation index, the quality of the river sediments can be regarded as being moderately polluted to very highly polluted with Cr, Ni, Cu, Zn, Pb and Cd in the Delhi and Agra urban centres. The present sediment analysis, therefore, plays an important role in environmental measures for the Yamuna River and the planning of these city centres. Received: 21 June 1999 · Accepted: 1 October 1999     

The role of karst in the genesis of sulfur deposits, Pre-Carpathian region, Ukraine

 Most of exogeneous epigenetic sulfur deposits are clearly associated with intensely karstified carbonate and sulfate rocks. This paper demonstrates, using the Pre-Carpathian region as an example, that karstification is one of the most important processes controlling the formation of sulfur deposits. This is determined by a coincidence of some major prerequisites of these two processes. In the Podol'sky and Bukovinsky regions the Miocene aquifer system is well drained by erosion valleys; the giant network caves known here in gypsum formed under past artesian conditions. In the region of sulfur deposits, associated with the same karstified gypsum strata, true artesian conditions still prevail. Hydrogeologic data show that abundant cavities detected in the vicinity of sulfur deposits can be interpreted as having the same origin as the fossil caves of the Podol'sky and Bukovinsky regions. The current widespread belief that the gypsum/anhydrite stratum in the region is aquifuge separating the Miocene aguifers is inadequate. This belief caused much controversy with regard to the genetic interpretations of sulfur deposits in the region. Caves formed by the upward water flow through the gypsum/anhydrite stratum govern the water exchange between the aquifers within the aquifer system. A new karst model for the formation of sulfur deposits is suggested. It agrees well with the hydrogeological features of the Miocene sequence and with biogeochemical mechanisms of sulfur origin in low-temperature diagenetic environments. Received: 16 February 1995 · Accepted: 4 June 1996