Detecting inter-aquifer leakage in areas with limited data using hydraulics and multiple environmental tracers,including <Superscript>4</Superscript>He, <Superscript>36</Superscript>Cl/Cl, <Superscript>14</Superscript>C and <Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr

The investigation of regionally extensive groundwater systems in remote areas is hindered by a shortage of data due to a sparse observation network, which limits our understanding of the hydrogeological processes in arid regions. The study used a multidisciplinary approach to determine hydraulic connectivity between the Great Artesian Basin (GAB) and the underlying Arckaringa Basin in the desert region of Central Australia. In order to manage the impacts of groundwater abstraction from the Arckaringa Basin, it is vital to understand its connectivity with the GAB (upper aquifer), as the latter supports local pastoral stations and groundwater-dependent springs with unique endemic flora and fauna. The study is based on the collation of available geological information, a detailed analysis of hydraulic data, and data on environmental tracers. Enhanced inter-aquifer leakage in the centre of the study area was identified, as well as recharge to the GAB from ephemeral rivers and waterholes. Throughout the rest of the study area, inter-aquifer leakage is likely controlled by diffuse inter-aquifer leakage, but the coarse spatial resolution means that the presence of additional enhanced inter-aquifer leakage sites cannot be excluded. This study makes the case that a multi-tracer approach along with groundwater hydraulics and geology provides a tool-set to investigate enhanced inter-aquifer leakage even in a groundwater basin with a paucity of data. A particular problem encountered in this study was the ambiguous interpretation of different age tracers, which is attributed to diffusive transport across flow paths caused by low recharge rates.     

Granitoid magmatism of the Lermontovskaya and Vostok-2 tungsten ore-magmatic systems: U-Pb (SHRIMP) dating and isotope characteristics (<Superscript>3</Superscript>He/<Superscript>4</Superscript>He) of ores

U-Pb (SHRIMP) isotope dating of magmatic complexes of tungsten ore-magmatic systems (OMSs) resulted in a conclusion about the close age (103–105 Ma) of their formation in the magmatic rock masses from the Tatibinsk plutonic series whose location is controlled by the Sikhote-Alin’ strike-slip fault system. The OMSs are formed within the zones of strike-slip fault extensions (“windows”) dipping into the mantle, which establishes the conditions for the participation of deep fluids in the generation of melts at the level of crustal-mantle interaction. The new data from the study of the isotope composition of helium in the fluid inclusions showed that the content of mantle helium in ores of tungsten OMSs is approximately 10%.     

Differential behavior of components of the <Superscript>238</Superscript>U-<Superscript>206</Superscript>Pb and <Superscript>235</Superscript>U-<Superscript>207</Superscript>Pb isotopic systems in polymineralic U ores

U-Pb systems were examined in samples (ranging from 4 to 10 cm³ in volume) of ore material taken from along a 3.5-m profile across a zone of U mineralization exposed in an underground mine at the Strel’tsovskoe U deposit in eastern Transbaikalia. The behaviors of two isotopic U-Pb systems (²³⁸U-²⁰⁶Pb and ²³⁵U-²⁰⁷Pb) are principally different in all samples from our profile. While the individual samples are characterized by a vast scatter of their T(²⁰⁶Pb/²³⁸U) age values (from 112 to 717 Ma), the corresponding T(²⁰⁷Pb/²³⁵U) values vary much less significantly (from 127 to 142 Ma) and are generally close to the true age of the U mineralization. The main reason for the distortion of the U-Pb system is the long-lasting (for tens of million years) migration of intermediate decay products in the ²³⁸U-²⁰⁶Pb(RD²³⁸U) in the samples. This process resulted in the loss of RD²³⁸U from domains with high U concentrations and the subsequent accommodation of RD²³⁸U at sites with low U concentrations. The long-term effect of these opposite processes resulted in a deficit or excess of ²⁰⁶Pb as the final product of ²³⁸U decay. The loss or migration of RD²³⁸U are explained by the occurrence of pitchblende in association with U oxides that have higher Si and OH concentrations than those in the pitchblende and a higher ⁺⁶U/⁺⁴U ratio. The finely dispersed character of the mineralization and the loose or metamict texture of the material are the principal prerequisites for RD²³⁸U loss and an excess of ²⁰⁶Pb in adjacent domains with low U concentrations. Domains with low U contents in the zone with U mineralization serve as geochemical barriers (because of sulfides contained in them) at which long-lived RD²³⁸U(²²⁶Ra, ²¹⁰Po, ²¹⁰Bi, and ²¹⁰Pb) were accommodated and subsequently caused an excess of ²⁰⁶Pb. The ²³⁵U-²⁰⁷Pb system remained closed because of the much briefer lifetime of the ²³⁵U decay products. This may account for the significant discrepancies between the T(²⁰⁶Pb/²³⁸U) and T(²⁰⁷Pb/²³⁵U) age values. RD²³⁸U was most probably lost via the migration of radioisotopes at the middle part and end of the ²³⁸U family (starting with ²²⁶Ra). The heavy Th, Pa, and U radioisotopes (²³⁴Th, ²³⁴Pa, ²³⁴U, and ²³⁰Th) that occur closer to the beginning of ²³⁸U decay, before ²²⁶Ra, only relatively insignificantly participated in the process. Our results show that the loss and migration of RD²³⁸U are, under certain conditions, the main (or even the only) process responsible for the distortion of the U-Pb system.     

Cosmogenic radionuclide <Superscript>7</Superscript>Be concentration in seven species of lichens and its correlation with <Superscript>40</Superscript>K, <Superscript>137</Superscript>Cs and <Superscript>226</Superscript>Ra

In this work, accumulation of cosmogenic radionuclide ⁷Be in seven species of lichens was determined using HPGe detectors in autumn season. Ramsar city which is located in the north of Iran as one of the high-level natural radiation areas in the world was considered. Lichen species represented good potential in accumulation of ⁷Be radionuclide. The foliose species of Xanthoria parietina with the highest activity concentration value of 112.8 ± 1.8 Bq kg^?1 was introduced as bioindicator for accumulation of ⁷Be radionuclide. Cladonia rangiformis species has got minimum concentration of 64.5 ± 0.8 Bq kg^?1. Also from thallus morphology viewpoint, results showed that ⁷Be accumulation in foliose species is higher than in fruticose and crustose lichens species. Also there was relatively large positive correlation between ⁷Be and ²²⁶Ra activity concentrations in lichens species.     

<Superscript>226</Superscript>Ra, <Superscript>232</Superscript>Th and <Superscript>40</Superscript>K activities in soils of Cuihua Mountain National Geological Park,China

Gamma activity from the naturally occurring radionuclides namely, ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K was measured in the soil of Cuihua Mountain National Geological Park, China using γ-ray spectrometry technique. The mean activity of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 27.2 ± 6.5, 43.9 ± 6.2 and 653.1 ± 127.6 Bq kg⁻¹, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities of Chinese soil. The radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, and the external hazard index were evaluated and compared with the internationally approved values. All the soil samples have Ra_eq lower than the limit of 370 Bq kg⁻¹ and H _ex less than unity. The overall mean outdoor terrestrial gamma dose rate is 66.3 nGy h⁻¹ and the corresponding outdoor annual effective dose is 0.081 mSv.     

Structural Transformations and Retention of Radiogenic <Superscript>4</Superscript>He in Platinum Minerals under Mechanical Deformations

The results are presented of the first studies to be carried out on ⁴He retention under mechanical deformation of isoferroplatinum (Pt₃Fe) from a unique placer deposit at the Konder and Uorgalan rivers and from indigenous shows of the alkaline–ultrabasic Konder Massif (Khabarovsk krai, Russia). It was found that the deformation of Pt₃Fe of the Pm-3m cell resulted in structural transformations with the appearance of domains and subsequent conversion into native platinum (Pt, Fe) of the Fm-3m cell.     

Granitoid magmatism in the Arminskii block of Central Sikhote Alin (Primorye,Far Eastern Russia): U–Pb geochronology, <Superscript>3</Superscript>He/<Superscript>4</Superscript>He isotopy,petrochemistry, and ore mineralization

This work presents the first isotope-geochronological data obtained for granitoid series of the Arminskii block of Central Sikhote Alin: Tatibi gabbromonzodiorite and Olgino leucocratic granite. Every series is characterized by a certain structural position and timing of the formation of ore mineralization. The Tatibi series is characterized by the presence of gold-ore occurrences including the potential Glukhoe goldore occurrence. Granitoids of the Olgino series comprise known tin–sulfide ore occurrences. The conditions for the generation of each series of rocks were revealed on the basis of geochronological-isotope data.     

Chemical and isotopic (<Superscript>18</Superscript>O/<Superscript>16</Superscript>O and D/<Superscript>1</Superscript>H) composition of groundwaters of central and southern Primorye

Groundwaters of Primorye, including its coastal areas, were studied during the past ten years. The macro-and microelement composition of more than 130 samples showed that shallow groundwaters of southern Primorye with pH ranging between 5.4 and 8.4 contain oxygen (up to 10 mg/l) and typically have a mixed ionic composition. The microelement variations reflect both the natural features of the host rocks and possible anthropogenic pollution in the most populated areas. No seawater intrusions were recognized in the study areas, which is confirmed by the chemical composition of the waters, the oxygen and hydrogen isotopic composition of the groundwaters, the atmospheric precipitation, and the coastal seawaters of Primorye. In spite of the variations of individual components, the quality of the groundwaters used for potable purposes is rather satisfactory as compared to the Russian and the World Health Organization standards. At the same time, taking into account the increase of various microelements and biogenic components in the waters, the monitoring and control of the water composition is strongly recommended to preserve their potable quality.     

Measurement of marine productivity using <Superscript>15</Superscript>N and <Superscript>13</Superscript>C tracers: Some methodological aspects

Various experiments involving the measurement of new, regenerated and total productivity using ¹⁵N and ¹³C tracers were carried out in the Bay of Bengal (BOB) and in the Arabian Sea. Results from ¹⁵N tracer experiments indicate that nitrate uptake can be underestimated by experiments with incubation time <4 hours. Indirect evidence suggests pico- and nano-phytoplankton, on their dominance over microphytoplankton, can also influence the f-ratios. Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both ¹⁵N and ¹³C tracers suggest that photoinhibition appears significant in BOB and the Arabian Sea during noon. A significant correlation has been found in the productivity values obtained using ¹⁵N and ¹³C tracers.     

Correlation of δ<Superscript>18</Superscript>O and initial<Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr ratios in Kirkpatrick basalt on Mt. Falla,transantarctic mountains

Theδ¹⁸O (SMOW) values of the Kirkpatrick Basalt (Jurassic) on Mt. Falla, Queen Alexandra Range, vary between +6.3‰ and +8.6‰ The apparent enrichment of these rocks in¹⁸O excludes the possibility that they were altered by interaction with aqueous solutions of meteoric origin. Theδ¹⁸O values of the flows correlate significantly with the initial⁸⁷Sr/⁸⁶Sr ratios and all major elements. These correlations confirm the hypothesis that the basalt magma was contaminated by rocks of the continental crust through which it was extruded. Estimates of the chemical composition of the basalt magma and the contaminant, based on extrapolations of the new oxygen data, generally confirm earlier estimates based on extrapolations of initial⁸⁷Sr/⁸⁶Sr ratios. The⁸⁷Sr/⁸⁶Sr ratio of the uncontaminated basalt was 0.7093 which indicates that magma may have originated by melting either in old Rb-enriched lithospheric mantle under Antarctica or in the overlying crust, or both.     

The barents sea magmatic province: Geological-geophysical evidence and new <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dates

Resulting from study of the geological structure of the Franz Josef Land and Svalbard archipelagoes, this work presents new 17 ⁴⁰Ar/³⁹Ar age datings for basalts taken during coastal expeditions in 2006–2010. Radiological age determination for intrusive units (sills) located in the western part of Nordensciold Land (Spitzbergen Island) has been made for the first time. In relation to use of the interpretation results of marine geological-geophysical data, the distribution peculiarities and time ranges for Jurassic-Cretaceous basic magmatism within the studied regions of the Barents Sea continental margin and within the Arctic as a whole are discussed.     

<Superscript>238</Superscript>U and <Superscript>235</Superscript>U isotope fractionation upon oxidation of uranium-bearing rocks by fracture waters

The variations in ²³⁸U/²³⁵U values accompanying mobilization of U by fracture waters from uranium-bearing rocks, in which U occurs as a fine impregnation of oxides and silicates, were studied by the high-precision (±0.07‰) MC–ICP–MS method. Transition of U into the aqueous phase in the oxidized state U(VI) is accompanied by its isotope fractionation with enrichment of dissolved U(VI) in the heavy isotope ²³⁸U up to 0.32‰ in relation to the composition of the solid phases. According to the sign, this effect is consistent with the tendency of the behavior of ²³⁸U and ²³⁵U upon interaction of river waters with rocks of the catchment areas [11] and with the effect observed during oxidation of uraninite by the oxygen-bearing NaHCO₃ solution [12].     

Compositional controls on <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar ages of zoned mica from a rare-element pegmatite

A high spatial resolution Ar–Ar dating study of compositionally zoned micas using UV laser extraction has been used to investigate the effect of composition and compositional boundaries upon argon diffusion in mica. The crystals are characterised by muscovite cores and Li–F–Rb–Cs-rich lepidolite rims produced by the interaction of a residual melt-vapour phase with the original muscovite during the late stages of pegmatite crystallisation. Single crystals exhibit dramatic intra-grain age variations, with a maximum range of 2,880–2,117 Ma. Backscattered electron images combined with UV-laser analyses reveal that apparent ages younger than 2,600 Ma are directly associated with the compositionally distinct rims, suggesting that Ar diffusion was faster in the lepidolite than in muscovite. Although it is not possible to be fully quantitative using the present data, it seems that argon diffusion rates in lepidolite are similar to those in biotite. Major rearrangements of the crystal structure needed to accommodate high concentrations of lithium, fluorine and large interlayer cations (Rb⁺, Cs⁺) in muscovite account for lower argon retentivity of the crystal rims. In most cases the age profiles show no disturbance at the compositional boundary, despite the transition from a di-octahedral to tri-octahedral mica, indicating that in general the boundaries do not act as fast diffusion pathways. However, in some cases there is a clear drop in ages at the compositional boundary, which acts as an effective sub-grain boundary. The difference between the two types may be related to the internal structure of the compositional boundaries or their degree of contact with the grain boundary network of the rock.     

<Superscript>1</Superscript>H NMR-based serum metabolic profiling of <Emphasis Type="Italic">Carassius auratus gibelio</Emphasis> under the toxicity of Pb<Superscript>2+</Superscript> and Cd<Superscript>2+</Superscript>

Lead and cadmium are the two widely recognized toxic metals, with known ecological risk to freshwater fish in contaminated ecosystems. However, their effect at environmentally realistic level in a mixture has been rarely investigated. In the present study, serum metabolic responses of Crucian carp exposed to Pb (30 µgL^?1), Cd (100 µgL^?1) and Pb+Cd (30 + 100 µgL^?1) for 21 days were investigated by ¹H NMR-based metabolomics. The metabolic responses were compared to control by multivariate techniques (PCA, PLS-DA and OPLS-DA), and metabolites that significantly contributed to the variation were identified. Metal dependent metabolic responses revealed a decline of alanine, lysine and tyrosine in Pb exposed fish, indicating changes in neurotransmitters, and amino acid metabolism, while fish exposed to Cd showed significant decrease in lysine, isoleucine, leucine, alanine and increase in 3-hydroxybutyrate, acetone, lactate, choline, inosine, guanosine and threonine. The coexposure of Pb and Cd had additive effect on metabolic profile with increase in pyruvate, guanosine and inosine. The overall metabolic changes due to Pb and Cd were characterized by disturbed energy metabolism, impaired osmotic regulation and a shift from aerobic to anaerobic respiration. Moreover, ¹H NMR-based metabolomics was proved to be a powerful tool in elucidating the toxic effects of environmental pollutants and underlying mechanism.