Discrimination of metal contaminant sources in river sediments influenced by mining and smelting activities using stable Pb and Zn isotopes.

To determine the sources and pathways of lead (Pb) and zinc (Zn) in river sediments contaminated with metals from mining and smelting activities, metal concentrations and Pb and Zn isotope ratios were measured in river water and sediment, and potential metal contaminant samples (imported Zn concentrates, smelting wastes, soils around the smelter, mine ores, and riverside tailings). Zn and cadmium (Cd) concentrations in river water and sediment samples were 30- and 11-25-fold higher, respectively, near the smelter than upstream, while a 6-fold increase in sediment Pb concentrations was detected over the same region. Sediment samples near the smelter (207Pb/206Pb = 0.8638 and 208Pb/206Pb = 2.0960) were observed to have a different Pb isotopic composition from upstream of the smelter (207Pb/206Pb = 0.8322 and 208Pb/206Pb = 2.0502), with δ66Zn values increasing from -0.01 to 0.82‰. Analysis of Pb and Zn isotopes and concentrations revealed that dust-contaminated soils were a major Pb source, and baseline sediments were found to be contaminated by regional mining tailings. For Zn in sediments, the main Zn sources were groundwater-derived Zn (δ66Zn = 1.02 ± 0.43‰, n = 4), dust-contaminated soils (δ66Zn = -0.18 ± 0.08‰, n = 3), and tailings-contaminated sediments (δ66Zn = 0.01 ± 0.07‰, n = 10). Endmember mixing model results showed that dust-contaminated soils contributed 78% and 64% of sediment Pb and Zn, respectively, within 2 km of the Zn smelter, decreasing to negligible levels after 47.1 km downstream. Downstream of the smelter, groundwater-derived Zn contributed 54% of sediment Zn, whereas tailings contaminated sediments contributed 70% and 25% of Pb and Zn, respectively.

Spatio-temporal accumulation and sources of anthropogenic Pb in Ulleung Basin sediments, East/Japan Sea, based on stable Pb isotope ratios.

The accumulation, pathways, and sources of anthropogenic lead (Pb) in Ulleung Basin sediments were investigated based on the temporal and spatial variations in the Pb concentration and stable Pb isotopes for 21 dated box core sediments collected from the shelf, slope, and basin in the southern East/Japan Sea. Leached (1 M HCl) Pb concentrations and isotope ratios (207Pb/206Pb and 208Pb/206Pb) were nearly constant before 1930, but have increased rapidly until the present. The primary source of anthropogenic Pb is considered to be atmospheric deposition, showing the signature of a mixture of leaded gasoline and coals, which was the major anthropogenic source in the basin. However, after the 1990s, anthropogenic Pb from dumping materials added as much as 10-25% to the slope sediment and has been spreading out from the water column accompanied by the movement of the East Sea Intermediate Water. In shelf areas, inputs from nonferrous refineries in the coastal industrial complexes play an important role in pollution from anthropogenic Pb.

Mercury contamination of sediments in an open coastal area of the Hupo Basin, East Sea, Korea.

Mercury (Hg) contamination in open coastal areas has attracted public concern regarding safe fish consumption and management of the coastal environment, especially in areas of accidental Hg spills on inland coasts. This study investigated the temporal and spatial distribution of Hg in sediments of Youngil Bay and the Hupo Basin, East Sea, Korea; it also discussed the sources and transport of anthropogenic Hg. Hg hot spots were found in the northern Hupo Basin (elevated by 2-3×) and the river mouth area in Youngil Bay (elevated by approximately 70×). The river mouth contamination resulted from the destruction of a dam impounding landfill waste, while the basin contamination was attributed to atmospheric deposition and Hg enrichment associated with increased organic carbon concentrations driven by high biological production in the coastal upwelling area. Spilled Hg was transported to open coastal areas up to 36.6°N.

Spatial patterns of Zn, Cd, and Pb isotopic compositions of ground and surface water in mine areas of South Korea reflecting isotopic fractionation during metal attenuation.

As application of multiple metal isotopes can effectively constrain geochemical behavior of contaminants and assess contamination sources and pathways, field-scale studies on the geochemically interlinked fractionation of Zn and Cd isotopes in groundwater are needed. In this study, we collected groundwater samples from multi-level samplers downstream of tailings dumps as well as surface water, ore mineral, precipitate, and tailings samples at the Sambo and Buddeun metallic ore mines in South Korea, and analyzed their Zn, Cd, Pb, and sulfur isotopic compositions. Furthermore, isotopic ratios of ore mineral samples from additional four mines in South Korea (Dangdu, Dongbo, Gomyeong, Samgwang) were compared. A dual isotopic approach using Zn and Cd isotopes was used to assess fractionation processes, and Pb isotopic signatures reflecting their sources were assessed. Increasing trends of δ66Zn and δ114Cd with decreasing Zn and Cd concentrations were observed in groundwater, which was saturated with respect to ZnS (amorphous and sphalerite) and CdS (greenockite). Moreover, for some groundwater samples, δ66Zn showed a positive relationship with δ34SSO4. These results suggest that Zn and Cd are precipitated as sulfide following sulfate reduction. In the plot of δ66Zn against δ114Cd, relatively high and/or increasing δ66Zn in groundwater suggested the effect of fractionation due to sulfide precipitation, while variable and high δ114Cd values suggested the fractionation by adsorption and/or sulfide precipitation, which were based on positive fractionation factors for δ66Zn and δ114Cd during sulfide precipitation and mostly negative and positive fractionation factors for δ66Zn and δ114Cd, respectively, during adsorption. This study shows that the combined use of Zn and Cd isotopes in groundwater can effectively differentiate between adsorption and sulfide precipitation following sulfate reduction in groundwater. Additionally, the 208Pb/206Pb ratios of most water samples reflected those of ore and tailings samples, which verified usefulness of Pb isotopes in water in investigating Pb contamination sources.

Assessment of heavy metal contamination in sediments along the coast of South Korea using Cs-normalized background concentrations.

To assess metal contamination in sediments along the entire coastline of South Korea, we estimated the regional background concentrations of metals and assessed the degree of contamination. Major and heavy metal concentrations, grain sizes, and sedimentation rates were analyzed. Regional background concentrations were established by identifying uncontaminated sediments in the cores, using first-order linear regression of background concentration against Cs concentration. The metal contamination of surface sediments was assessed using Korean sediment quality guidelines and a modified geo-accumulation index (Igeo⁎). In total, 14 sediments exceeded the threshold and probable effects level for Cu, 39 for Zn, and 19 for Pb. Based on Igeo⁎, most sediments were not contaminated with Cr, Co, or Ni, whereas 31% (Zn), 34% (Cu), and 43% (Pb) in total surface sediments were contaminated with other metals; 14% of total sediments were contaminated with Cu, and those above class 2 were concentrated near industrial and shipyard facilities.

Source identification of heavy metal contamination using metal association and Pb isotopes in Ulsan Bay sediments, East Sea, Korea.

To determine the characteristics of metal pollution sources in Ulsan Bay, East Sea, 39 surface and nine core sediments were collected within the bay and offshore area, and analyzed for metals and stable lead (Pb) isotopes. Most surface sediments (>95% from 48 sites) had high copper (Cu), zinc (Zn), cadmium (Cd), and Pb concentrations that were as much as 1.3 times higher than background values. The primary source of metal contamination came from activities related to nonferrous metal refineries near Onsan Harbor, and the next largest source was from shipbuilding companies located at the mouth of the Taehwa River. Three different anthropogenic sources and background sediments could be identified as end-members using Pb isotopes. Isotopic ratios for the anthropogenic Pb revealed that the sources were imported ores from Australia, Peru, and the United States. In addition, Pb isotopes of anthropogenic Pb discharged from Ulsan Bay toward offshore could be determined.

Regional background concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb) in coastal sediments of the South Sea of Korea.

The background concentration (BC) of metals in coastal sediments may be a useful tool for assessing the extent of sediment contamination by human activities. This study presents an approach to establish BCs that are applicable at the regional scale, particularly for coastal areas with relatively tortuous coastlines and complex coastal geology and/or geomorphology like the South Sea of Korea. The approach is based on the sorption hypothesis for metal enrichment of coastal sediments and was verified using 33 core and 187 surface sediments. The concentrations of major and heavy metals, grain size parameters, organic carbon, and sedimentation rates were determined. Cs was selected as the most suitable geochemical normalizer to correct the grain-size effect. Non-contaminated samples from core sediments were selected according to the sedimentation rate, 32 types of profile pattern based on metal concentrations and metal/Cs ratios, and their variability in past sediments. Metal concentrations in the selected non-contaminated samples were well correlated with Cs, with a given Cs amounts in surface sediments corresponding to the lowest metal concentrations. This result supported the use of a procedure based on the sorption hypothesis, which was then used to synthesize all core samples and establish the regional BC of heavy metals in the coastal sediments. Linear regression equations between metal and Cs concentrations provided the following BCs of metals in coastal sediments in the South Sea of Korea: 70 (Cr), 13 (Co), 30 (Ni), 13 (Cu), 87 (Zn), and 23 (Pb)mg/kg at 8mg/kg of Cs (mean concentration of 393 sediments).

Historical record of metal accumulation and lead source in the southeastern coastal region of Korea.

Concentrations of heavy metals and Pb isotopes were measured in the 1-M HCl leaching fraction of core sediments spanning the last 400 years. This sedimentary record of pollution history in metal concentrations shows a good correlation with the increases in industrialization, urbanization, and energy consumption since 1901s. Notably, the Pb concentration and the (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios were constant before the 1910s (16.7 µg/g, 0.844, and 2.098, respectively), whereas they increased steadily up to 21.9 µg/g, 0.848, and 2.101 after the 1910s. The correlations between Pb isotope ratios ((206)Pb, (207)Pb, and (208)Pb) showed different linear regression trends for core sediments before and after the 1910s, indicating differences in Pb sources. Our interpretation suggests that the source of anthropogenic Pb in Korean coastal region and the Yellow Sea shelf was presumed to be Chinese coals or ores, which have also played a major role as sources of atmospheric particulate Pb.

Lab-on-a-disc for simultaneous determination of nutrients in water.

In this study, we describe a novel platform based on centrifugal microfluidics for simultaneous determination of nitrite, nitrate and nitrite, ammonium, orthophosphate, and silicate in water samples. All processes from sample metering to detection were integrated and automatically conducted on a rotating disc-shaped device. Fluid transfer was controlled by laser irradiation on the ferrowax-based microvalves. Liquid samples and reagents were pumped by centrifugal force in the rotating disc, and their positions and movements were controlled through a programmable light from a laser diode. This novel water analysis platform required only 500 µL of sample (100 µL for each nutrient) and 10-30 µL of reagents for colorimetric detection. In addition, the fully automated parallel processes and efficient mixing in the rotating disc allowed for a significant reduction in total analysis time (∼7 min 40 s) and increased accuracy. Validation with a seawater certified reference material indicated that the platform accurately measured nutrient concentrations in water samples. In addition, we showed that the nutrients in the seawater collected from Chunsu Bay in Korea measured by the proposed lab-on-a-disc and by a commercialized autoanalyzer are comparable.

Analysis of rare earth elements in seawater by inductively coupled plasma mass spectrometry after pre-concentration using TSK™-HD-MW-CNTs (highly dispersive multi-walled carbon nanotubes).

This study aimed to identify easy-to-use multi-walled carbon nanotubes (MW-CNTs) having a high capacity to adsorb metals and thereby expand the usability of these materials as a solid-phase adsorbent for the analysis of trace metals in seawater. High-dispersion-type MW-CNTs had the highest metal binding capacity (70.8±5.1 mg/g for La) after a strong acid oxidation procedure, possibly because the high dispersibility resulted in a more complete reaction than with highly crystalline types. Because the high-dispersion-type MW-CNTs leaked from a conventional column, they were attached to polymer beads (TSK™) (pore diameter about 20 µm). Flow rate, pH, and volume of the seawater sample, as well as eluent type and volume, were optimized to obtain 0.01-0.16 pg/mL detection limits for rare earth elements (REEs). In addition, normalized patterns for samples collected from the East Sea showed characteristic features of REEs in seawater, i.e., a negative Ce anomaly, low atomic number REE (LREE) depletion, and high atomic number REE (HREE) enrichment.

Characterizing the effect of heavy metal contamination on marine mussels using metabolomics.

Marine mussels (Mytilus) are widely used as bioindicators to measure pollution in marine environments. In this study, (1)H NMR spectroscopy and multivariate statistical analyses were used to differentiate mussel groups from a heavy metal-polluted area (Onsan Bay) and a clean area (Dokdo area). Principal component analysis and orthogonal projection to latent structure-discriminant analysis revealed significant separation between extracts of mussels from Onsan Bay and from the Dokdo area. Organic osmolytes (betaine and taurine) and free amino acids (alanine, arginine, glutamine, phenylalanine, and threonine) were more highly accumulated in Onsan Bay mussels compared with Dokdo mussels. These results demonstrate that NMR-based metabolomics can be used as an efficient method for characterizing heavy metal contamination derived from polluted area compared to clean area and to identify metabolites related to environments that are contaminated with heavy metals.

Chemical and isotopic compositions of bottled waters sold in Korea: chemical enrichment and isotopic fractionation by desalination.

A total of 54 Korean bottled waters were investigated to characterize their origins and types using elemental and isotopic composition, as well as to identify elemental and isotopic changes in desalinated marine water that arise due to desalination. The different types of bottled water displayed a wide pH range (3.42 to 7.21). The elemental compositions of still and sparkling waters were quite similar, whereas desalinated marine water was clearly distinguished by its high concentrations of Ca, Mg, B, and Cl. In addition, desalinated marine water had much higher isotope ratios of oxygen and hydrogen (-0.5 and -2‰, respectively) than still and sparkling waters (-8.4 and -57‰). The elemental composition of desalinated marine water was adjusted through post-treatment procedures; in particular, boron was greatly enriched during desalination processes. The carbon isotope compositions of dissolved inorganic carbon (δ(13)C(DIC) values) varied widely according to the origins of the bottled waters (-25.6 to -13.6‰ for still water, -31.2 to -26.7‰ for sparkling water, and -24.1 to -6.3‰ for desalinated marine water). This indicates that carbon isotopes in dissolved inorganic carbon are significantly fractionated by desalination processes and re-modified through post-treatment procedures. The results suggest that combined elemental and stable isotopic tracers are useful for identifying the origin of bottled water, verifying elemental and isotopic modifications during desalination processes, and characterizing various water types of bottled waters.

Direct determination of gold in rock samples using collision cell quadrupole ICP-MS.

This study investigated the determination of Au in rock samples using collision cell quadrupole inductively coupled plasma mass spectrometry (ICP-MS). It is essential to remove various interferents using a collision cell because polyatomic ions such as (181)Ta(16)O(+) and (180)Hf(16)O(1)H(+) can interfere with the direct determination of monoisotopic (197)Au when using ICP-MS. The addition of oxygen as a reaction gas removed isobaric interferents by transforming TaO(+) and HfOH(+) to TaO(2)(+), TaO(3)(+), and HfO(2)H(+), HfO(3)H(+), respectively, in the cell without significant Au(+) loss. The ion kinetic energy effect (IKEE) due to the potential difference between the plasma and the hexapole affected the reactions in the cell. Au and interfering ions were very sensitive to cell bias voltage (Vc) at constant plasma potential (Vp) and quadrupole bias voltage (Vq). Under the condition of hot plasma, the transmission of ions was promoted, and the maximum Au signal intensity was 50% greater than under normal conditions. At Vc > 7 V, TaO(+) ions were removed to background level. Optimized conditions for real sample analysis were obtained by introducing He as an additional collision gas in hot plasma. TaO(+) ions were removed to background level at He flow rates above 0.6 mL min(-1), and the Au signal remained high. The detection limit (three times the standard deviation of the blank) of this method was 3.06 pg g(-1). The results for reference materials (STM-1 and DGPM-1) and spiked samples showed good agreement between specified and measured concentrations.

A multianalytical approach for determining the geographical origin of ginseng using strontium isotopes, multielements, and 1H NMR analysis.

Asian ginseng (Panax ginseng C.A. Meyer) is widely used as an Oriental medicine in the East Asian regions, particularly Korea and China. In the study, the strontium isotope ratios ((87)Sr/(86)Sr), multielements, and metabolite profiles of 35 ginseng samples collected from Korea and China were examined in an attempt to develop a method to distinguish the origin of ginsengs from the two countries. A multivariate statistical approach was performed to analyze the multielements and the (1)H nuclear magnetic resonance (NMR) data. Results of a t-test for Mg, Fe, Al, and Sc showed significant variation between Korean and Chinese ginsengs, indicating potential tracers for discriminating them. Discriminating between the ginsengs from the two countries was generally successful when both the (87)Sr/(86)Sr ratios and rare earth element (REE) contents were used together. Moreover, principal component analysis (PCA) derived from the (1)H NMR data revealed a significant separation between the ginsengs originating from the two countries. The major metabolites responsible for differentiation were sugars such as glucose, xylose, and sucrose. The results suggest that this multiplatform approach offers a comprehensive method to distinguish the origin of ginsengs.

Atmospheric metal and phosphorus concentrations, inputs, and their biogeochemical significances in the Japan/East Sea.

Atmospheric metals and phosphorus over the southern Japan/East Sea were investigated in order to evaluate their sources, concentrations and inputs, and to identify their biogeochemical roles in this marginal sea. Aerosols were collected on the east coast of Korea from February 2002 to April 2003 (n=101) as well as at a remote island (Ulleung) and on a ship from February 2002 to June 2003 (n=13). The aerosols were analyzed for Al, Co, Cu, Ni, P, Pb and Zn. Simultaneous collections of aerosols at both coast and offshore were performed, and several high dust aerosols (Al>5 microg m(-3)) were collected at both regions. At the coastal site, both dust mineral and pollutants were transported by westerly winds from the Asian continent, but local emissions were significant (e.g., Cu, Ni, P and Zn) as well during the summer monsoon (May-August). The experimental relationships between the coast and offshore sites were defined. From these relationships, it was possible to obtain the annually averaged atmospheric metal and P concentrations over the southern Japan/East Sea, which has increased by over 2 times for the last decade. Through the estimation of atmospheric metal and phosphorus fluxes and comparisons with inputs from the Tsushima Warm Current, the atmospheric pathway was found to be a significant source for Al, Pb and Zn.

239+240Pu concentration and isotope ratio (240Pu/239Pu) in aerosols during high dust (Yellow Sand) period, Korea.

Concentration and isotope ratio of Pu were analyzed for aerosols collected at Anmyeondo located in the western coast of Korea using multiple collector inductively coupled plasma mass spectrometer equipped with desolvated micro-concentric nebulizer. Aerosols were collected from June 2001 to April 2002 using high volume air sampler. The samples consist of high dust samples (Yellow Sand), and also low dust samples; maximum Al concentration was 74.2 microg/m(3) and minimum was 0.17 microg/m(3). Pu was concentrated using 0.1 ml TEVA resin columns after conc. HNO(3) extraction. Isotope dilution using (242)Pu spike and mass bias correction using (233)U and (236)U mixed solution enabled the quantification of Pu and measurement of isotope ratio simultaneously. The contribution of (238)U from both spikes and samples was minimized by careful chemical separation and optimization of spike concentration. The (238)U(1)H and tail contribution on (239)Pu peak were about 0.75 x 10(-5) and 1 x 10(-5) of (238)U intensity, respectively, and they were corrected from (239)Pu using externally determined ((238)U(1)H + tailing)/(238)U ratio and (238)U measurement during acquisition. The detection limits of this analytical procedure were 0.61 fg/ml and 0.56 fg/ml for (239)Pu and (240)Pu, respectively (4 nBq/m(3) and 12 nBq/m(3) for (239)Pu and (240)Pu, respectively). The precision of isotope ratio measurement was better than 2% for larger quantity than 20 fg of (239)Pu. In spring, maximum concentration of 0.580 microBq/m(3) for (239)Pu and 0.404 microBq/m(3) for (240)Pu was observed when Al concentration was maximum, so called as Yellow Sand event. Pu concentrations in aerosols are well correlated with Al, a tracer of soil dust. The ratios of Pu/Al were 0.0082 (microBq/microg) and 0.0055 (microBq/microg) for (239)Pu/Al and (240)Pu/Al, respectively. Isotope ratios of Pu ((240)Pu/(239)Pu) in Yellow Sand samples show 0.191+/-0.014 close to those of global fallout. These facts indicate that Yellow Sand plays an important role in the behavior of Pu in the environment like other concomitant metals such as Al, Fe etc.