The Daliao River System (DRS) estuary in the Liaodong Bay has a highly industrial, urbanized, and agricultural catchment. The objective of this study was to investigate the multi-elemental geochemistry in the estuarine and coastal sediments, including enrichment, sources, toxicity, and geochemical baselines. Thirty-five sediment samples were collected from the estuarine and coastal area and analyzed for As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, Sc, V, Y, Zn, P, Mn, Ti, Al, Fe, Ca, Mg, Na, and K. The average content (mg/kg) was 11.4 for As, 0.34 for Cd, 10.2 for Co, 60.8 for Cr, 20.0 for Cu, 0.05 for Hg, 22.6 for Ni, 26.6 for Pb, 71.8 for Zn, and 0.68 for Sb. The enrichment factor (EF) values of the trace elements, relative to the upper continental crust (UCC), ranged from 7.06 for As to 1.04 for Co, using Fe as a reference element. In general, As, Cd, and Sb were significantly or moderately enriched, while the other trace elements were not or were minimally enriched. The As and Ni in the sediments may pose potential toxicity to biota, while the Cd, Cr, Cu, Hg, Pb, and Zn might rarely or not pose toxicity. All elements except Ca, K, and Na were significantly and positively correlated with one another, with correlation coefficients of 0.523 to 0.994. Principal component analysis (PCA) revealed three groups of elements in association with secondary clay minerals, primary minerals, and carbonate minerals. Generally, the Cr, Cu, Hg, Ni, Pb, and Zn in the sediments originated from natural sources and their regional geochemical baselines (RGBs) were developed using Fe as a reference element. These RGBs may help identify the origins of these metals in the sediments of the Liaodong Bay and document their change over time.

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Three basic minerals, biotite, chlorite and amphibole, were mineralogically and chemically examined to specify primary host phase(s) of As in the aquifer sediments and verify the formation mechanism of As contaminated groundwater of Sonargaon, Bangladesh, where the highest As contaminated groundwater appears in actively recharging zones. Among those minerals, only the chlorite included As by μ-XRF analysis. Fe-rich and tritoctahedral nature indicated this chlorite termed chamosite. The chlorite was weathered to form goethite on the cleavage, however, the goethite did not host the As. Combining with the saturation of goethite in the groundwater (Itai et al., 2008), in situ chemical weathering of the chlorite promoted by accelerated aerobic water infiltration is suggested to be the first stage of formation of the As contaminated groundwater of the Holocene aquifer. This study implies the importance of aerobic aquifer condition to promote the As release via decomposition of As-bearing detrital mineral(s) as the formation mechanism of As contaminated groundwater in the Ganges-Bramaptra-Meghna river basin.

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The Banian sediment-hosted antimony deposit is a medium-sized deposit located in the Dushan County, South Guizhou, China. Calcite is the dominant gangue mineral and can be divided into two types: white and pink. Pink calcite is intimately associated with mineralization. Sm-Nd dating of five white calcites yield an isochron age of 128.2 ± 3.2 Ma, with initial ε_Nd = -4.3 and MSWD = 0.54, while six pink calcites yield an identical age of 126.4 ± 2.7 Ma with initial ε_Nd = -6.0 and MSWD = 0.68. These new age constraints suggest that the Banian deposit formed during the late Yanshanian. Negative initial ε_Nd values, C (-0.5 to -1.8), O (12.5 to 14.6) isotopic characteristics of calcites, and field observations of abundance of vuggy open spaces, all suggest significant interaction between fluid and wall rocks. Calcites are characterized by strongly LREE-depleted and MREE- and HREE-enriched (LREE/HREE = 0.11-0.61). Stibnites are LREE-enriched, and MREE- and HREE-depleted (LREE/HREE = 105-500). Wall rocks are characterized by moderate LREE-enriched (LREE/HREE = 6.2-12). Pink calcites are more enriched in LREE (LREE/HREE = 0.11-0.61) than white calcites (LREE/HREE = 0.11-0.23), while the concentration of HREE remains nearly constant in both. The high contents of Fe and Mn in calcites and the negative correlation between Fe+Mn (ppm) and LREE/HREE ratios suggest that the Fe-Mn impurities in calcites may dominate the enrichment of MREE and HREE in calcites from the Banian deposit.

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X-ray absorption fine structure (XAFS) analysis was applied to elucidate Cr(VI/III) speciation during reaction with standard humic acid materials extracted from Japanese soils. The degree of reduction of Cr(VI) by humic acids differed for different degrees of humification. Adsorption of Cr(III) to humic substances was higher for higher carboxylic humic substance contents. After reduction experiments of Cr(VI) by humic acids, Cr binding with humic acids has a trivalent state. Nevertheless, a substantial amount of Cr(VI) remains in solution. The X-ray absorption near-edge structure (XANES) spectra of the Cr(VI) experimental system were almost identical to those of Cr(III) adsorbed onto humic acids in a low-pH condition. However, during adsorption of Cr(III) by humic acids, Cr was partly precipitated as Cr(OH)₃·nH₂O. Its concentration was higher for higher pH. XANES spectra of Cr(VI/III) reacted with different humic acids showed no systematic differences, indicating that the binding form of Cr to humic substances is common, irrespective of differences in functional group concentrations. Linear combination fitting using XANES spectra of reference compounds to HA-Cr samples suggests that 50% hydrated Cr(III) was adsorbed onto HA and that the remainder of Cr(III) was bound to carboxylic acid of HA. The local structure of Cr binding to humic acids was characterized using extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS features of Cr binding to humic acids were similar to those of Cr³⁺ aquo ions having simple octahedral symmetry of the oxygen coordination sphere. They show no clear presence of carboxylic group of humic acids around the Cr site. Scattering from the C atom might not be visible because the backscatter amplitude of a C atom becomes weak steeply with increasing wavenumber (k) and because it is smaller than those of the O atom and the Cr atom. Considering the linear combination fitting results of XANES spectra, the structural mode of Cr binding with HA is R-COO-Cr-(OH₂)₅.

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The aim of the present work is to investigate the distribution and possible sources of phthalate esters (PAEs) in groundwater and surface water of a subtropical Dongguan city, South China. Groundwater and surface water samples were collected from fifty-six and nine sampling sites in 2006, respectively. Concentrations of six PAE compounds (Σ₆PAEs) in groundwater and surface water range from below detection limit (BDL) to 6.7 μg/L and from BDL to 33.8 μg/L, with an average value of 0.9 μg/L and 11.1 μg/L, respectively. Of the six PAE compounds in groundwater and surface water, di (2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) are the main compounds of PAEs. DnBP and DEHP are predictive indicators for the Σ₆PAEs in surface water (r = 0.803, p < 0.01) and groundwater (r = 0.726, p < 0.01), respectively. Most of high Σ₆PAEs in groundwater are measured near the boundary of Dongguan city. In contrast, the Σ₆PAEs in groundwater samples are BDL in the center of Dongguan city. The concentration of DnBP in groundwater is negatively correlated with groundwater table (R = 0.6496, p < 0.05), while there is no correlation between DEHP concentration and table in groundwater. Our results indicate the high Σ₆PAEs in surface water and the good hydraulic connection between surface water and groundwater. Thus, the PAEs in surface water may be one of the main sources for those in groundwater in the study area.

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A total of 74 surface and subsurface water samples at depths shallower than 200 m were collected in the eastern East China Sea (ECS), and spatial and seasonal variations in ²²⁶Ra, ²²⁸Ra, and ²²⁸Th activities were examined by low-background γ-spectrometry. The ²²⁸Ra and ²²⁸Th activities (as well as ²²⁸Ra/²²⁶Ra and ²²⁸Th/²²⁸Ra activity ratios) on the surface exhibited notable seasonal and lateral variations (²²⁸Ra/²²⁶Ra = 0.2-3.4; ²²⁸Th/²²⁸Ra = 0.1-0.4). From the ²²⁸Ra activity (0.2-6 mBq/L) and salinity (27.2-34.5), fractions of the Kuroshio, shelf, and Yangtze River waters on the surface of the ECS were estimated to be 50-95%, 3-50%, and 2-8% in July, and 95-100%, 1-5%, and 0-1% in April, respectively, exhibiting a lower fraction of shelf water in winter-spring and on the Japan side of the ECS. While the surface waters had high ²²⁸Th activity (~0.1-0.6 mBq/L) in July, resulting from the high activity of the parent ²²⁸Ra, their ²²⁸Th/²²⁸Ra ratio (~0.1) was lower compared with that of waters in February-April (0.15-0.35). ²²⁸Th is considered to be preferentially removed from the surface in summer, reflecting a high flux of biogenic particles.

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To evaluate the source of sulfur and the extent of seasonal and local characteristics in Seoul’s precipitation chemistry, we measured sulfur, oxygen, and hydrogen isotopic ratios of precipitation. The pH of precipitation ranges from 4.6 to 7.0 in Seoul. Precipitation shows positive correlations between ions in the Ca²⁺-Mg²⁺-SO₄^2--NO₃^- system, indicating that the dissolution of Ca and Mg particles by H₂SO₄ and HNO₃ from the combustion of fossil fuels is a major process controlling the chemical composition of snow and rain. The values of oxygen and hydrogen isotope composition of rain range -15.7~-3.2‰ and -114.7~-18.0‰, respectively. The H and O isotope values in the summer are plotted near the global meteoric water line by Craig (1961). The d-excess values in winter are higher than 10, which indicate that the source of rain during winter is a dry air mass from continental China. The sulfur isotope ratio of precipitation in Seoul ranges from +3.0 to +7.3‰, which is similar to typical metropolitan air pollution levels. The data suggests that the main source of sulfur is SO₂ produced by the combustion of fossil fuels. The pollutant SO₄ is estimated to have a δ³⁴S_nss range from +1.0 to +6.2‰ in the Seoul area. The δ³⁴S values of precipitation range from +5.1 to +7.3‰ (mean +6.4‰) in winter and from +3.0 to 4.8‰ (mean +4.0‰) in summer. The higher δ³⁴S values in winter (December and February) seem to be correlated to the air mass from northern China, of which the δ³⁴S values of oil or coal is higher than that of southern China. The lower sulfur isotopic values in summer (June to August) are correlated to the air mass moving from southern China. Isotopic composition and chemical concentrations of SO₄ depend on wind provenance, thus supporting the idea that a seasonally transported source for the pollutant sulfur is from China.

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We applied laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) techniques to make spatial measurements of chemical tracer concentrations in three natural rock types (tuff, sandstone, greywacke) in order to characterize important processes affecting chemical fate and transport (e.g., diffusion, sorption, imbibition, and advective transport). Specifically, we (1) evaluated LA-ICP-MS factors (e.g., spot size, laser pulse, primary grain size, and surface roughness) affecting quantitative laser sampling in both surface and depth mapping; and (2) applied LA-ICP-MS to investigate the fate and transport processes of a suite of chemicals (both nonsorbing and sorbing) in natural rock through laboratory studies of imbibition, diffusion under both saturated and unsaturated conditions, and transport in a rock core traversed by a saw-cut fracture. The results indicate that micro-scale mapping using LA-ICP-MS is a robust and sensitive technique for evaluating fate and transport of chemical species in natural rock. Direct mapping of chemical distributions using LA-ICP-MS techniques in natural rock offers distinct advantages over other methods of study, such as batch sorption experiments using crushed rock samples, and through-diffusion studies involving lengthy experiments during which test conditions may be difficult to maintain. Values of sorption distribution coefficient as determined using LA-ICP-MS techniques with centimeter-sized tuff samples, are consistently smaller, in both imbibition and diffusion experiments, than those obtained from batch-sorption tests using crushed samples with grain sizes in the 0.5-2.0 mm range.

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