We determined the stable carbon isotope compositions (δ13C values) of perylene and compounds coexisting with it to elucidate the precursor of perylene in sediments of Lake Biwa. Although we found a high amount of friedelin (6.5 μg g-1) in extracts, originating mainly from C3 angiosperms, its δ13C value (-30.8‰±0.1‰) was different from that of perylene (-27.8‰±0.3‰). The δ13C values of friedelin and perylene lay within the ranges for Japanese angiosperms (C3, -37.5‰ to -28.6‰) and gymnosperms (C3, -28.3‰ to -26.0‰), respectively. Since these values were clearly more negative than those of Japanese aquatic plants (C3, -16.5‰ to -14.6‰), it can be considered that the perylene originated from the land, principally from gymnosperms.
In order to increase the sensitivity of static-mode noble gas mass spectroscopic analysis, we have developed and tested a gas re-circulation system, which uses a commercially available turbo molecular pump (TMP). During the analysis, the sample gases are directed from the collector end towards the ionization source part of the flight tube. Our preliminary results indicate that the apparent sensitivity of krypton and xenon can be increased by a factor of about 20 and 50, respectively. We also found that the gain factor of helium was somewhat smaller and was approximately 2. Such mass-dependence is quite consistent with the compressibility of TMP which is larger for the heavier molecules.
Hourly measurements of atmospheric methyl chloride (CH3Cl) and methyl bromide (CH3Br), as well as some other halocarbons, were performed by using automated preconcentration gas chromatography/mass spectrometry at Hateruma Island, the southernmost inhabited island in the Japanese archipelago. Our data indicate that CH3Cl and CH3Br concentrations were occasionally increased without corresponding increases of anthropogenic halocarbons, such as HCFC-22. Those nonpollution high-CH3Cl and high-CH3Br events were observed mostly when the wind was blowing at rather low speed along the shore (a partially vegetated raised coral beach). Presuming that these methyl halides were accumulated while the air mass traveled over the beach, the emission strengths of CH3Cl and CH3Br from the beach were roughly estimated to be 900 ± 350 μg m-2h-1 and 21 ± 10 μg m-2h-1, respectively. Coastal beach is likely a new important source for CH3Cl and CH3Br on a global scale.
To provide a better understanding of potential hazard of effluent detritus, both at the present and in the future, the dispersal and accumulation of sewage-derived materials in the receiving river should be addressed. For the goals, we determined concentrations and isotopic compositions of sedimentary organic carbon (SOC) and nitrogen (SON) and those of effluents in an urban river (Nanming River, China). In the river, the two major sources of sedimentary organic matter (SOM) are effluent detritus (δ13C: -25.0‰; δ15N: +8.5‰; C/N: 8.1) and C3 plants growing along the river bank (δ13C: -27.7‰; δ15N: -0.9‰; C/N: >28). Isotopic difference between the two end-members was observed to be 9.4‰ for nitrogen, compared with 2.7‰ for carbon, and hence nitrogen isotopic difference between end-members is large enough to be used as a tracer for source recognition of SOM. Using a mixing model, we found that at outfalls sewage-derived SON accounted for >60% of the bulk SON. At site 40 km far from outfall, fraction of sewage-derived SON was still high to 50%. But at most sites, though about 450,000 m3 sewage effluents per day discharge into the river, effluent detritus and C3 plants contributed nearly the same to SOM, indicated that natural contribution from C3 plants should be also paid attention to.
Upper Paleocene to Lower Eocene phosphates of the Jebel Oum El Khecheb profile (Gafsa-Metlaoui Basin GMB, Tunisia) are mostly composed of brown phospharenites lithified or not, granular, with pellets, coproliths, bone clasts and fish teeth. The matrix in analyzed samples is reduced and constituted of various clay minerals (dominantly smectites, palygorskite, sepiolite and rare kaolinite), opal-CT and carbonates. Clinoptilolite is recognized along the series; very few amounts of quartz and feldspar grains are sparsely present. The phosphate mineral is a carbonate-fluorapatite (CFA) sulphated, sodic enriched in strontium and rare earth elements (REE). Statistical analyses of mineralogical and geochemical data highlight the associated elements in the main mineral lattice. In the CFA, the group is composed of CaO-P2O5-Na2O-SO3-F-Sr-Th-REE-U-Ba-Zr-Cr. In the silicates, the group contains SiO2-Al2O3-Fe2O3-MgO-K2O-Na2O-TiO2-Co-Cs-Rb-Sc-Ta-Sb-Mo-As and Cu. Sulphides are represented by Zn and Cd; iron oxides by mainly Fe and Ni. Dolomite and gypsum are present; SO3 is contained in the latter, but CFA may also have some of this radical in its structure. The Upper Continental Crust (UCC) normalized REE patterns present a variably negative Ce-anomaly, suggesting that the imprint of the marine genesis environment is very well-preserved in the main phosphatic units. Positive-Eu and negative-Sm anomalies were detected in some samples. The fractionation of light-REE to heavy-REE, represented by the La/Yb ratio of untreated values varies between 8.28 and 12.94, somewhat less than UCC value (13.64). Enrichment of HREE is due to phosphates. Both ratios reflect the marine genesis environment wherein the formation of the CFA took place in a confined and oxygen poor environment. Then the CFA removed the REE and the trace elements present from the interstitial waters, as was proposed for the various phosphatic basins of Tunisia.
Mn-rich layers and interbedded shales from a well exposed natural section of the Northern-Calabrian Unit (Late Jurassic-Early Oligocene) in the surroundings of the Terranova del Pollino village, southern Italy, have been mineralogically and chemically analyzed, in order to reveal the factors controlling their formation. Mn-rich layers are composed of micas/clay minerals, rhodochrosite, siderite, chlorite and quartz whereas shales are formed by micas, clay minerals, chlorite, quartz, and feldspars. The MnO abundances in the Mn-rich layers, which are depleted relatively to the UCC in SiO2, TiO2, Al2O3, Na2O, K2O, and P2O5, are in the range of 11.01 ÷ 18.41 (wt. %). R-mode Factor analysis indicate that SiO2, Al2O3, TiO2, Na2O and K2O have high positive weights in the first factor (59.8% of the total variance) whereas high negative weights are observed for Fe2O3, MnO, and CaO. This factor accounts for the competition between the terrigeneous component, the authigenic carbonate phases accumulating Mn and Fe which likely formed during paucity of detrital supply. The negative weight of CaO and MnO in this factor, the higher Ca contents in the Mn-rich layers compared to shales, and the lack of calcite, suggest the presence of a mixed Mn-Ca carbonate rather than pure rhodochrosite. It is generally retained that Ca-rhodochrosite precipitates within the pore waters of reducing sediments since neither rhodochrosite nor siderite can form in equilibrium with bottom seawater. Thus the resulting sediment should be a mixing between the detrital component and the authigenic one. Assuming Al2O3 as an index of the detrital component, it is clearly envisaged that in the Al2O3/MnO vs. Al2O3 diagram the carbonate-rich samples fall on the mixing curve having as end members the average shale and the richest MnO sediment. This supports the idea that carbonate-rich samples formed through precipitation of carbonate minerals in the pore waters of the terrigenous detritus accumulating at the sea bottom. Further the REE distribution of unaltered marine carbonates is expected to be representative of ambient seawater where carbonates precipitated. Carbonates normalized to fine-grained siliciclastic sediments, have typical HREE enrichment, negative Ce-anomaly, and lower total REE. In our case, the carbonate-rich samples normalized to the average composition of the interbedded free-carbonate shale, show HREE enrichment, lower total REE contents, and the lack of negative Ce-anomaly, due to the anoxic environment of formation for Mn- and Fe-carbonate. Finally was observed that the mineralization is enhanced if the site of accumulation is protected from dilution by clastic sediment input. The alternation between Mn- and Fe-carbonate silts and carbonate-free shales along the studied sedimentary succession, were likely controlled by eustatic sea-level oscillations which are well documented in the western Tethys during Middle and Late Triassic.
The motile cells of the autotrophic dinoflagellates Peridinium umbonatum var. inaequale, Akashiwo sanguinea, Scrippsiella tinctoria, and Prorocentrum micans commonly contain five major sterols: cholesterol, 4-methylcholestan-3-ol, 4,24-dimethylcholestan-3-ol, dinosterol, and dinostanol. The motile cell of the heterotrophic dinoflagellate Protoperidinium crassipes contains cholesterol, 4,24-dimethylcholestan-3-ol, dinosterol, dinostanol, and 4-tetramethylcholestan-3-ol as major free sterols. The dinosterol concentrations of heterotrophic dinoflagellates are about 4-12 times higher than those of autotrophic species, suggesting that the heterotrophic dinoflagellate is an important source of dinosterol in some sediments. 4-Tetramethylcholestan-3-ol has not been reported in cultured samples of other heterotrophic dinoflagellates. The difference in 4-methyl sterol composition in heterotrophic dinoflagellates may be related to the feeds used during the culture experiment. The resting cyst of P. umbonatum var. inaequale contains 4-methylcholestan-3-ol, 4,24-dimethylcholestan-3-ol, dinosterol, dinostanol, and C31Δ5,22-sterol as major free sterols. The C31Δ5,22-sterol has not been reported in cultured samples of motile cells from dinoflagellates. This compound might be produced during the resting stage, and thus may serve as a potential biomarker for the resting cysts of dinoflagellates.
Being an inexpensive but efficient adsorbent, hydroxyapatite is extensively used for decontaminating wastewater and soils polluted by heavy metals. However, its solubility and grain size can affect its remediation effectiveness. This study investigated the ability of nano-hydroxyapatite (nano-HAP) to adsorb aqueous Cd, Pb and Cu ions from single-metal and multi-metal ions reaction systems. Langmuir and Freundlich isotherm equations were employed to study the sorption constants. Based on the sum of squares errors (SSE), results showed that the Langmuir isotherm better fits sorption data than the Freundlich equation. The sorption affinity of nano-HAP for Pb(II) is always higher than that for Cu(II) and for Cd(II); the sorption maxima for the Cd, Pb and Cu follow the order Pb2+ > Cu2+ > Cd2+. This could be inversely proportional to the hydrated ionic radii as Pb2+ (4.01 Å) > Cu2+ (4.19 Å) > Cd2+ (4.26 Å). The measured selectivity coefficients in multi-metal (Cd-Pb-Cu) reaction systems shows that Pb has the highest sorption selectivity on nano-HAP among the metals investigated. This sorption selectivity coincided well with the sorption affinity order in mono-metal reaction systems. The pH of the solution is an important parameter in controlling Cd, Pb and Cu ions sorption on nano-HAP. Indeed, the nano-HAP sorption capacity increases with increasing pH up to a value of 6.25. This implies that the removal of metals from the solution is recommended for pH ≈ 6.25 or below, during remediation using nano-HAP as a sorbent.
A total evaporation negative thermal ionization mass spectrometry (TE-N-TIMS) technique for the isotopic analysis of chlorine was developed. This technique provides fast and reliable way to determine the isotopic signature of chlorine samples as small as 100 ng. Compared to the conventional N-TIMS method, the precision of the Cl isotopic analysis is improved by a factor of up to 3 by minimizing the effect of mass fractionation. Using this method, reproducibility of 0.9‰ (R.S.D.: n = 25) can be achieved for 37Cl/35Cl ratio of 200 ng Cl. The analyzed results of the AgCl reagent expressed as a per-mil deviation (δ37Cl) relative to the Standard Mean Ocean Chloride showed good concordance with the value obtained by conventional positive thermal ionization mass spectrometry (P-TIMS).
It is still debated whether there is a variation of the atmospheric 3He/4He ratio, due to the anthropogenic release of radiogenic 4He contained in fossil fuels, in modern era. In this study, we measured the He isotopic ratios in old Chinese and Japanese porcelains assuming that the old atmosphere might have been preserved in vesicles. The trapped noble gases are elementally but not isotopically fractionated. The 3He/4He ratios in some old Chinese porcelain are significantly higher than the present air value, indicating that recent human industrial activity might have affected the helium isotopic ratio of the atmosphere. Our result indicates that the rate of change in the atmospheric 3He/4He ratio was -0.034 ± 0.018 %/year (2σ) in the last 200 years. Results show that porcelain can be used as a time capsule of the paleoatmosphere during historical age.
Mn/Cr relative sensitivities for a synthetic calcite and a terrestrial olivine (San Carlos olivine) were measured using spot and rasterized modes with a NanoSIMS ion probe. Counting rates of 43Ca+, 52Cr+, 53Cr+ and 55Mn+ from the synthetic calcite by spot analysis mode decreased with time (and depth of crater). This may be interpreted as due to charge-up of the deep crater formed by primary ion bombardment because of poor conductivity of carbonate. The relative Mn/Cr sensitivity of carbonate measured by spot analysis mode decreased with time. It may be necessary to use a time-dependent relative sensitivity factor for chronological studies of meteoritic carbonates. The time-averaged RSF for the calcite spot analysis is significantly lower than that for San Carlos olivine. The instrumental isotopic fractionation of the 53Cr/52Cr ratio measured with the NanoSIMS 50 seems to be different between the calcite and San Carlos olivine.