We propose an analytical protocol for the accurate in situ determination of 176Hf/177Hf isotope ratios in zircon crystals by a 193 nm ultraviolet excimer laser ablation (193ExLA) multiple-collector inductively coupled plasma mass spectrometer (MC-ICPMS). Specifically, we used a simultaneous laser and dry solution aerosol dual sample introduction (DSI) system equipped with the 193ExLA-MC-ICPMS and an ARIDUS II desolvating nebulizer. The DSI-MC-ICPMS analyzed the laser aerosol from the zircon crystal while deionized water was aspirated from the ARIDUS II. Hf standard solutions were analyzed using the ARIDUS II with the laser switched off. This technique provides the same analytical conditions for both the laser and solution aerosols minimizing changes in the plasma condition. Therefore, the instrumental mass bias correction using a standard solution is accurately achieved. The instrumental mass bias for 176Hf/177Hf was corrected by measuring 179Hf/177Hf. 176Yb interference correction on 176Hf was performed using the 176Yb/173Yb ratio with a 173Yb/171Yb internal mass bias correction for Yb. Similarly, 176Lu interference was adjusted for using 176Lu/175Lu with 173Yb/171Yb or 179Hf/177Hf external mass bias correction. These correction factors were carefully determined using standard solutions. The correction factors were stable over three months, as observed by our routine monitoring. Standard zircons of 91500, TEMORA 2, Plešovice, and FC-1 were analyzed using 193ExLA with laser fluence at 20 J/cm2 and a repetition rate of 5-10 Hz. The ablation conditions resulted in craters of 40 μm diameter and 40 μm depth after a few minutes. Standard bracketing using JMC475 solution was applied every one to five spot laser analyses, thereby correcting for any remaining instrumental mass bias. The resultant 176Hf/177Hf isotope ratios were all in excellent agreement with the isotope ratios reported by TIMS and by other LA-MC-ICPMS analyses.
The distribution of heavy metals in recent sediments deposited along the Tietê River, a highly polluted river in southeast region of Brazil was studied. Around the metropolitan area of São Paulo city (25 million people), the pollution is related to municipal wastes and industrial effluents with reinforced downstream by agricultural activities. The observed increase of heavy metal concentrations is particularly important for Zn in the upper basin and Cu, Co and Cr at mouth. Geo-accumulation index calculation, related to the regional background, showed that the sediments along the basin are seriously polluted by heavy metals of anthropogenic origin, mainly Cu, Co, Cr and Zn. Calculated index suggests medium to very strongly pollution.
Chemical composition, hydroxyl radical (•OH) photoformation rate (ROH) and primary generation sources of •OH in water-extract of aerosol (WEA) and aqueous solution of water-soluble gases (WSG) in the atmosphere were studied at Higashi-Hiroshima, Japan from June 2008 to June 2010. Among the major anions present in the WSG samples, the SO42- concentration was highest (9.4 ± 4.0 nmol m-3), followed by NO3- and Cl-, while the mean concentration of SO42- in the WEA fraction was 81 ± 33 nmol m-3. The initial concentrations of H2O2 were 0.2 ± 0.3 and 0.9 ± 2.3 nmol m-3 in the WSG and WEA, respectively. The extracted sample was irradiated using a solar simulator, after which the ROH was determined and normalized against the sun-light intensity of a clear sky midday on May 1 at 34°N, which revealed values of 1.4 and 0.5 nmol h-1 m-3 for the WEA and WSG, respectively. The contribution of NO3-, NO2- and H2O2 to the formation of •OH via photolysis was 4.5, 0.7 and 1.2%, respectively, for the WSG fraction, while in the WEA fraction, the contribution was 8.9, 1.2 and 2.5%, respectively. Other contribution sources of •OH could include the photo-Fenton reaction and fluorescent matter such as humic-like substances (HULIS). The photo-Fenton reaction was estimated to potentially contribute up to 42% of the total •OH formation in the WSG fraction, while the fluorescent matter may account for the remaining 52%.
The analysis of major elements and polycyclic aromatic hydrocarbons (PAHs) were carried out on surface hydrothermal sediments collected from the Kairei hydrothermal field on the Central Indian Ridge (CIR) and the Logatchev hydrothermal field on the Mid Atlantic Ridge (MAR). The most characteristic PAHs in the samples were the low molecular weight (LMW) analogs present in a significantly high proportion. Values of the fluoranthene/pyrene (F/P) ratio indicated that PAHs originated from a pyrolytic process. The relative abundance of phenanthrene and its alkyl homologs characterized by the following order C0 > C1 > C2 > C3 > C4, and this result suggested that less biodegradation had occurred in the hydrothermal organic matter. However, a severe secondary oxidation or thermal loss of Benzo[a]pyrene (BaP) would have happened due to the presence of Benzo[e]pyrene (BeP) and absence of BaP in the PAHs. The hierarchical cluster analysis (HCA) showed that these samples could be grouped into four clusters, and all members in the same cluster had a similar inorganic geochemical characteristic. On the basis of canonical correspondence analysis (CCA), the PAH compositions were correlated well with those of inorganic elements. Among them, LMW PAHs such as biphenyl, naphthalene and fluorene were more related to the Talc formation environment, where the Si rich fluids meet the Mg rich seawater. These intermediate weight (IMW) PAHs such as phenanthrene, dibenzothiophene and retene showed a positively relation with metal elements (Fe, Cu and Zn), which may represent a plume fall-out environment. Lastly, the high molecular weights (HMW) PAHs including chrysene, fluoranthene and BeP showed a major positive correlation with environment of the chimney wall. These results suggest that the different molecular weight PAHs might be prone to distribute in different hydrothermal occurrence among the hydrothermal system.
Strontium-Neodymium isotopes and 28 elements for Kimberlites from China (Shandong and Liaoning) and from South Africa (Kimberley area) have been measured to estimate their chemical characteristics and magma sources. The εSr and εNd values for Chinese kimberlites were, respectively, +1.0 to +93.0 and -4.3 to +0.2. The isotopic signature for all Shandong samples revealed very similar to those of Group I kimberlites (South African samples), whereas the Liaoning samples were categorized as Transitional. Although primitive mantle-normalized trace element patterns of the mean values of Group I Shandong and South African samples all resembled those of other Group I kimberlites, their HREE concentrations differed slightly. Shandong samples were depleted in HREEs. Our model calculation demonstrated that the kimberlites would be produced by partial melting with degree of less than 1%. Furthermore, Shandong samples were possibly generated from source rock in which the mineral contents differed slightly (specifically the proportion of garnet) from those of other regions.
Microparticles recovered from the Asteroid 25143 Itokawa surface by the Hayabusa mission have been examined for the occurrence of soluble organic compounds. After five individual particles (~50 to 100 μm in diameter) were rinsed with organic solvents on a diamond plate, two extracts were hydrolyzed with hydrochloric acid for amino acid analysis (AAA), and three extracts were combined for time of flight-secondary ion mass spectrometry (ToF-SIMS) to look for other organic compounds, including polycyclic aromatic hydrocarbons. The organic compounds detected by both methods have the same concentrations as those in blank levels, indicating that indigenous organic compounds are not found in this study. Based on the sensitivities of AAA and ToF-SIMS with the reference sample analyses, the concentrations of indigenous organics in the samples are below part-per-million (ppm), if present.
Vertical profiles of iodine-131 and cesium-137 emitted from the Fukushima Daiichi Nuclear Power Station were determined in soil core samples collected in Fukushima prefecture. The profiles showed that more than 76% of the radionuclides were retained within 5 cm of the surface. Leaching experiments showed that cesium was strongly bound to soil particles which could not be leached with 2 M HCl, while more than 40% of iodine was incorporated into humic substances.
In March 2011, an accident at the Fukushima Daiichi nuclear power plant (FNPP-AC) was caused by the Tohoku earthquake and tsunami. Here we show the distribution of artificial caesium-134 and -137 (134Cs and 137Cs) in the western North Pacific one month after the FNPP-AC. In surface seawater, 137Cs concentrations were from several times to two orders of magnitude higher than before the FNPP-AC. 134Cs was also detected, and in many seawater samples the 134Cs/137Cs ratio was about 1. These findings indicate that radionuclides from the FNPP dispersed quickly in the western North Pacific. 134Cs and 137Cs concentrations in suspended solids and zooplankton at stations K2 and S1 were also one to two orders higher than before the accident. Numerical simulation results show that the higher caesium observed in the western North Pacific one month after the FNPP-AC was transported not only by diffusion and advection of seawater but also via the atmosphere as an aerosol.
We performed chemical analyses of commercially bottled spring water (EREK Spring water) emanating from a location less than 20 kilometer from the epicenter of the Mw = 7.2 Van Earthquake of October 23rd 2011. The available water samples cover the period from September 8th 2011 to January 11th 2012. The pre-earthquake anomaly is characterized by a slight but clear increase in Ca2+, Mg2+, K+ and Cl- contents and decrease in Na+ and SO42- contents compared to the background. Post-seismic samples show decreasing trends in Ca2+, Mg2+, K+ and Cl- and increasing trends in Na+ and SO42-. All ion concentrations reach stability approximately one month after the earthquake. These results indicate that spring water chemical anomalies may be monitored as potential geochemical pre-earthquake indicators.
Korean Ministry of Environment (MoE) has implicated regulations to determine if the levels of environmental contaminants exceed regulations levels. The Korean MoE adopted a partial extraction method which extracts the exchangeable fraction for heavy metals or metalloids because concern was targeted on the environmentally available fractions. However, in 2010, they have revised the test method to a total extraction using aqua regia which can extract the residual fraction as well as environmentally available phases. If one follows the new standard method, solidification/stabilization (S/S) could not meet the new criteria, since the total concentration of heavy metals and metalloids in soil would not be changed after S/S procedures as remediation technique.