Isotopic Results Research Articles

Carbon isotopic constraints on the degradation and sequestration of organic matter in river‐influenced marginal sea sediments

AbstractOrganic matter degradation and sequestration in marine sediments are important processes involved in carbon cycling in the ocean. Here, we present the results of carbon isotope (14C and 13C) and concentration measurements of sedimentary organic carbon (SOC), pore‐water dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) in sediments collected from the East China Sea, Yellow/Bohai Sea, and South China Sea. Our results indicated that selective degradation and preservation of organic matter occurred in these sediments, and marine‐derived young organic carbon degraded preferentially and rapidly, resulting in high concentrations of pore‐water DOC and DIC with distinct carbon isotopic signatures. The average 14C age of pore‐water DOC was thousands of years younger than that of SOC in the sediment, suggesting that DOC was newly produced and cycled much faster than SOC. Aged SOC was refractory and preserved in sediments. Using a dual‐isotope three‐end‐member model, the contributions of potential sources to SOC, DOC, and DIC were estimated. Marine‐derived biomass organic carbon contributed the most to DOC, and dissolution of biogenic carbonate contributed the most to DIC. Riverine inputs of pre‐aged soil and fossil organic carbon dominated the SOC pool. Our study demonstrated that marginal sea sediments are important sites of young DOC and DIC fluxes into the water column, thus acting as a major pathway for carbon and nutrient cycling in the ocean.

Monospecific mass occurrence of a new species of the Early Jurassic genus Arzonellina (Brachiopoda) at Fenyveskút (Bakony Mountains, Hungary)

A peculiar slab of brachiopod coquina was found at Fenyveskút locality (Lókút, Bakony Mountains, Hungary). The current investigation demonstrated that it was a mass occurrence of monospecific brachiopods which belong to the kingenoid genus Arzonellina Sulser, 2005, recently described from Switzerland. Detailed investigations of the external and internal morphology (the latter by serial sections) of the specimens proved that they represent a new species: Arzonellina bogicae n. sp. This new species is introduced, described and illustrated here in details. The age of the brachiopod coquina and the new species is considered Sinemurian on the basis of circumstantial evidence from the locality Fenyveskút, where the lithologically very similar, Sinemurian Hierlatz Limestone is frequent. The previously documented occurrences of Arzonellina in Switzerland and Montenegro are also Sinemurian in age. For better understanding the sedimentary history of the slab of brachiopod coquina with Arzonellina, the Jurassic megabreccia at the locality Fenyveskút is re-described here. The lithology and fossils of the major components (blocks) and the matrix are documented in detail, and illustrated with thin section photomicrograps. Detailed study of the sediments that accumulated in an internal open space (vug) of the formerly lithified (cemented) brachiopod coquina revealed that the piece of the Arzonellina coquina was incorporated into the megabreccia in the Bajocian. The monospecific mass accumulation of brachiopods gave a hint to an association with hydrocarbon seeps (“cold seeps”). However stable isotopic results from the Fenyveskút locality do not show any signatures that would indicate the influence of that special environment.

Molecular and isotopic evidence for the origin of light oils and associated gases in the onshore northeast Nile Delta

The Nile Delta is a prolific hydrocarbon province in Egypt and the eastern Mediterranean region, particularly for gas resources. However, the origin of discovered hydrocarbons from the onshore Nile Delta has not been comprehensively studied. Fourteen condensates and 10 natural gas samples retrieved from Oligocene–Pliocene pay zones in the onshore northeast Nile Delta were studied for their molecular and isotopic composition to infer origin, source lithology, organic facies, depositional environment, thermal maturity, and reservoir secondary alteration. The isotopic compositions of the analyzed condensates indicate non-marine waxy oils. Results show that these condensates have high Pr/Ph ratios (1.86–6.46), abundant C19 and C20 tricyclic terpane contents relative to the C23 homologue, elevated oleananes, paucity of gammacerane, high hopane/sterane ratios, very low abundance of homohopanes, low dibenzothiophene/phenanthrene ratios and high C29/C27 sterane ratios. Clay-rich source rocks with abundant Type-III terrigenous organic materials deposited in an oxic fluvio-deltaic setting are suggested for these condensates. Light hydrocarbon (C7) compositions indicate that all investigated condensates, except the Allium-1 sample, suffered evaporative fractionation within their reservoirs. Chemometric analysis based on 14 biomarker and isotopic results suggests 3 genetic oil families for these condensates. These oil families have geochemical characteristics that indicate various contributions of terrigenous and marine organic matter and different levels of thermal maturity. The molecular and isotopic results indicate that the onshore Nile Delta natural gases are wet-thermogenic in origin with no signs of microbial biodegradation. These gases were generated by secondary cracking of associated oils derived from Type-III and Type-II/III or Type-II kerogen. The condensate and associated gas samples from Oligocene pay zones have different geochemical signatures than those from Miocene reservoirs, suggesting derivation from different source rocks with variable levels of thermal maturity or the presence of multiple charge systems from a common source in the onshore Nile Delta.

Identification of Water Contamination Sources Using Hydrochemical and Isotopic Studies—The Kozłowa Góra Reservoir Catchment Area (Southern Poland)

The application of combined research methods, such as hydrochemical and isotopic analyses, facilitates understanding of the origin of water constituents and migration of contaminants in the aquatic environment. The presented study attempts to identify contamination sources affecting water quality within the Kozłowa Góra reservoir catchment area (southern Poland). A total of 100 water samples were collected from surface water (the Brynica river, streams, and the reservoir) and groundwater (a Quarternary aquifer) in four time periods. During fieldwork, the physicochemical parameters were measured (temperature, pH, electrical conductivity, redox potential, and dissolved oxygen). The chemical analysis included the determination of major ions (HCO3−, SO42−, Cl−, Ca2+, Mg2+, Na+, and K+), nutrients (NO3−, NO2−, NH4+, and PO43−), and total organic carbon. The study was complemented by isotopic analysis of sulphur and oxygen in sulphate, which enabled a more precise identification of stressors affecting water quality in different parts of the catchment area. Chemical and isotopic results (δ34S = 4.38–13.99‰; δ18O 3.59–13.30‰) revealed that wastewater discharges and agricultural activities have a significant influence on the chemistry of the Brynica River and other streams. At some sampling points, a lower quality of water was manifested by elevated concentrations of NO3− (up to 22.6 mg/L) and several other ions (e.g., up to 114 mg/L for Cl−, up to 51.52 mg/L for NH4+, and 12.5 mg/L for PO43−). The quality of groundwater was deteriorated mainly by infiltration of sewage from leaky septic tanks. The level of groundwater contamination varied depending on the location, as higher concentrations of major ions and values of electrical conductivity were observed in residential areas. The Brynica river, streams, and groundwater recharge the drinking water reservoir, and thus its quality depends on these sources. A dilution of water and the presence of biochemical processes led to a reduction of contaminant concentrations in the Kozłowa Góra reservoir (down to 3.5 mg/L for NO3−, 32 mg/L for Cl−, 0.21 mg/L for NH4+, and <0.05 mg/L for PO43−) compared to water in the river and streams supplying the reservoir. The study revealed the role of wastewater discharge and agricultural activities in the evolution of surface water chemistry. The results will be used in further research on the origin and migration of other substances in water, including microcontaminants.

Comparing isotopic estimates of paleoelevation from carbonates and volcanic glass from the Miocene-age Chucal Formation in northern Chile

Paleoaltimetry reconstructions of the Central Andes based on stable isotope data indicate variable timing and rates of uplift, reflecting the operation of multiple geodynamic mechanisms. There are a range of isotopic methods and proxies involved in these reconstructions, and it may be that biases inherent in some of these methods has led to misinterpretations. Here we explored the limitations of carbonate archives in reconstructing past elevations, including underestimation of paleoelevations by oxygen-isotope evaporative enrichment and carbonate formation in the subsurface. To conduct our test, we obtained stable isotope values of carbonates from the Western Cordillera in northern Chile at ~18.5–19.5°S, where previously published paleoaltimetry results from the same sections, based on the hydrogen stable isotope composition of volcanic glass, indicate that this region of the Andes has remained at high elevations (>4.4 km) since at least ~23 Ma. We present new oxygen and carbon isotopic, and clumped isotopic results, petrographic and sedimentologic observations, as well as major element abundance (ICP-MS and microprobe analyses) from lacustrine carbonates (marlstones) and cements in sandstones of the early Miocene Chucal Formation in the central Andes of northern Chile. The clumped isotope paleotemperature estimates range from 26 to 45 °C in lacustrine carbonates and 27 to 54 °C in cements. These results indicate that carbonates from this section do not reflect surface temperatures, suggesting clumped isotope resetting in a rock-buffered setting for marlstones and carbonate formation at depth in the presence of groundwater for cements in sandstones. In contrast, the oxygen and carbon isotopic values from carbonates appear to be primary and combined with Mg/Ca ratios and Na concentrations document the transition from lake deposition into a dominantly fluvial environment within the Chucal Formation, also indicating variable evaporative conditions during deposition. The paleoaltimetry estimates in carbonates significantly underestimate the results determined in volcanic glass, with paleoelevation results ranging between 1.4 km and 2.6 km in marlstones and from 2.6 and 3.6 km in cements.. The results presented in this study highlight the importance of using multiple proxies for paleoaltimetry reconstructions, especially in arid land settings where meteoric waters have been modified by evaporation.

FRUITS of the sea? A cautionary tale regarding Bayesian modelling of palaeodiets using stable isotope data

A recent paper by Bownes et al. (2017, Radiocarbon 59(5): 1275–1294) used the Bayesian modelling software package FRUITS (Fernandes et al. 2014, PLoS ONE 9(2): e87436) to argue that Neolithic individuals from Carding Mill Bay on the west coast of Scotland obtained up to ca. 21% dietary protein from marine sources. This is in contrast to previous interpretations of the same isotopic (δ13C and δ15N) data, which concluded that these individuals showed little if any use of marine resources (Schulting and Richards 2002, European Journal of Archaeology 5(2): 147–189). Resolving this discrepancy is important for our understanding of the nature of the Mesolithic–Neolithic transition not only on the west coast of Scotland, but along all of Atlantic Europe, since similar isotopic results to those obtained at Carding Mill Bay are widespread throughout the Neolithic and indeed later periods. We suggest that greater caution needs to be excercised in the interpretation of the output of Bayesian palaeodietary modelling, which can be very useful heuristically, but should not always be taken at face value. Given the large number of parameters employed in such models (diet isotopic values and nutrient concentrations, trophic level and tissue fractionations, etc.) and the uncertainty involved in almost all of them, a wide range of outcomes are possible, as we demonstrate in this paper. We reaffirm the overwhelmingly terrestrial nature of diet at Carding Mill Bay both through FRUITS modelling and through the new application of compound-specific δ13C analysis of single amino acids of humans and fauna from the site.

Fluid-rock interaction and fluid mixing in the large Furong tin deposit, South China: New insights from tourmaline and apatite chemistry and in situ B-Nd-Sr isotope composition

AbstractThe Furong tin deposit (South China) is genetically associated with the multiphase Qitianling batholith that consists of main-phase and minor, but more fractionated, late-phase granites. Several tourmaline and apatite generations are distinguished. Tourmaline (Tur) variants comprise pre-ore Tur-1 as disseminations and nodules in the late-phase granite, pre- to syn-ore Tur-2 as replacements in nodules and as veins crosscutting the late-phase granite and nodules, syn-ore Tur-3 in tin greisens, pre- to syn-ore Tur-4 as veins in the altered main-phase granite, and syn-ore Tur-5 from tin skarns in a distinct Ca-rich environment. Apatite (Ap) generations include accessory Ap-G in the main-phase granite, and Ap-I to Ap-III from three stages related to skarn-type mineralization (garnet-diopside stage-I, pargasite-phlogopite-cassiterite stage-II, and sulfide-rich stage-III). Textural and compositional features suggest that all tourmaline variants are hydrothermal in origin with alkali and schorl to foitite composition and minor extensions to calcic and X-site vacant tourmaline groups, whereas all apatite generations belong to fluorapatite with Ap-G crystallizing from the magma and Ap-I to Ap-III being hydrothermal in origin. The narrow range of tourmaline δ11B values (–14.8 to –10.4‰) suggests a single magmatic boron source in the ore-forming fluids. The similar rare earth element patterns and εNd(t) values (–8.2 to –5.9 for Ap-G and –8.0 to –7.3 for Ap-I) between magmatic and hydrothermal apatite indicate that the skarn-forming fluids are dominantly derived from granites. The 87Sr/86Sr ratios of Ap-I to Ap-III (0.70733–0.70795) are similar to the carbonate wall rocks, but distinctly different from the more radiogenic granites, indicating Sr exchange with carbonate rocks. Integrating previous H-O isotopic data, the tourmaline and apatite elemental and B-Sr-Nd isotope results suggest that the greisen-type ore formed by interaction of B-, Na-, Li-, Zn-, and Sn-rich magmatic fluids with the late-phase granite in a closed and reduced feldspar-destructive environment, whereas the tin skarns resulted from mixing of magmatic fluids with meteoric water and interaction with the carbonate wall rocks in an open system where oxygen fugacity changed from reduced to oxidized conditions. During fluid-rock interactions and fluid mixing, considerable Ca, Mg, V, Ni, and Sr from the host rocks were introduced into the ore system. Coupled hydrothermal minerals such as tourmaline and apatite have great potential to fingerprint the nature, source, and evolution of fluids in granite-related ore systems.

Hydrogeochemistry of porphyry-related solutes in ground and surface waters; an example from the Casino Cu–Au–Mo deposit, Yukon, Canada

The Casino Cu–Au–Mo deposit is one of the largest and highest-grade porphyries of its kind in Canada, residing in an unglaciated region of west-central Yukon. A batch of 22 stream water samples and eight groundwater samples were collected proximal to the deposit for the purpose of identifying the most diagnostic trace element and isotopic pathfinders associated with the hydrothermal mineralization, as well as establishing natural hydrogeochemical baselines for the area. Water chemistry around this deposit was investigated because: (i) the deposit has not yet been disturbed by mining; (ii) the deposit was known to have metal-rich waters in local streams; and (iii) the deposit has atypically preserved ore zones. Surface and ground waters around the Casino deposit are anomalous with respect to Cd (up to 5.4 µg l –1 ), Co (up to 64 µg l –1 ), Cu (up to 1657 µg l –1 ), Mo (up to 25 µg l –1 ), As (up to 17 µg l –1 ), Re (up to 0.7 µg l –1 ) and Zn (up to 354 µg l –1 ) concentrations. Sulfur and Sr isotopes are consistent with proximal waters interacting with the Casino rocks and mineralization; a sulfide-rich bedrock sample from the deposit has δ 34 S = −1.2‰ and proximal groundwaters are only slightly heavier (−0.3 to 3.1‰). These geochemical and isotopic results indicate interaction and dispersion of porphyry-related solutes in ground and surface waters and point to the suitability of hydrogeochemistry as a medium for mineral exploration for porphyry-style mineralization in the Yukon, and elsewhere in Canada. Supplementary material: Dissolved concentration data for major and trace elements for the ground and stream water samples from Casino are available at https://doi.org/10.6084/m9.figshare.c.5778911 Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

Neoproterozoic Metabasalts of the Tyya Complex of the Olokit Rift Trough (Baikal–Muya Belt): Composition, U–Pb Age, Isotope-Geochemical Characteristics, and Geodynamic Effects

Abstract—We present results of new mineralogical, geochemical, geochronological, and isotope (Sm–Nd, Rb–Sr, and O) studies of the volcanic rocks of the Tyya complex in the Olokit trough. These are normal tholeiitic basalts and scarcer basaltic andesites forming a fractionated series with mg# = 45–65, medium TiO2 contents (0.73–1.62 wt.%), low P2O5 contents (0.04–0.25 wt.%), and a significant domination of Na over K (Na2O/K2O = 2.1–50.0). The rocks are metamorphosed to greenschists, which are composed of chlorite, actinolite, epidote, and albite with quartz, titanite, ilmenite, and magnetite impurity. The metabasalts have is an age of 915 ± 5 Ma (zircon U–Pb dating) and are characterized by wide variations in εNd(T) (–3.5 to –11.9) and 87Sr/86Sr (0.70602–0.70732) and high δ18O values (9.0–15.2‰) as compared to the mantle ones. According to the isotope-geochemical characteristics, the studied metabasalts have features of both IAB and E-MORB. The Tyya metabasalts might have resulted from the melting of the lithospheric mantle with a subductional component. Comparison of the studied rocks with volcanic rocks of recent geodynamic settings shows their similarity to basalts of back-arc basins. The Tyya metabasalts might belong to a back-arc basin of the late Mesoproterozoic Nyurundukan island arc system.

Source and Strategy of Iron Uptake by Rice Grown in Flooded and Drained Soils: Insights from Fe Isotope Fractionation and Gene Expression.

Rice can simultaneously absorb Fe2+ via a strategy I-like system and Fe(III)-phytosiderophore via strategy II from soil. Still, it remains unclear which strategy and source of Fe dominate under distinct water conditions. An isotope signature combined with gene expression was employed to evaluate Fe uptake and transport in a soil-rice system under flooded and drained conditions. Rice of flooded treatment revealed a similar δ56Fe value to that of soils (Δ56Ferice-soil = 0.05‰), while that of drained treatment was lighter than that of the soils (Δ56Ferice-soil = -0.41‰). Calculations indicated that 70.4% of Fe in rice was from Fe plaque under flooded conditions, while Fe was predominantly from soil solution under drained conditions. Up-regulated expression of OsNAAT1, OsTOM2, and OsYSL15 was observed in the root of flooded treatment, while higher expression of OsIRT1 was observed in the drained treatment. These isotopic and genetic results suggested that the Fe(III)-DMA uptake from Fe plaque and Fe2+ uptake from soil solution dominated under flooded and drained conditions, respectively.

Multiple stable isotopes and geochemical approaches to elucidate groundwater salinity and contamination in the critical coastal zone: A case from the Bou-areg and Gareb aquifers (North-Eastern Morocco)

Mediterranean areas are characterized by complex hydrogeological systems, where water resources are faced with several issues such as salinity and pollution. Fifty-one water samples were gathered from the Bou-areg coastal and the Gareb aquifers to evaluate the source of water salinity and to reveal the processes of the different sources of pollution using a variety of chemical and isotopic indicators (δ2H–H2O, δ18O–H2O, δ34S–SO4, and δ18O–SO4). The results of the hydrochemical analysis of water samples show that the order of dominated elements is Cl− > HCO3− > SO42- > NO3− and Na+ > Ca2+ > Mg2+ > K+ and evidenced extremely high salinity levels (EC up to 22000 μS/cm). All samples exceeded the WHO drinking water guidelines, making them unfit for human consumption. Ion ratio diagrams, isotopic results, and graphical comparing indicate that the mineralization of groundwater in the area, is controlled by carbonate dissolution, evaporite dissolution, ion exchange, and sewage invasion. The return of irrigation water plays a significant role as well in the groundwater recharge and its mineralization by fertilizers mainly. Evaporites (Gypsum), sewage, and fertilizers constitute the main sources of sulfates in the investigated water resources. These scientific results will be an added value for decision-makers to more improve the sustainable management of groundwater in water-stressed regions. The use of chemical and isotopic tracers once again shows their relevance in such zones where systematic monitoring is lacking.

Influence of equilibration time, soil texture, and saturation on the accuracy of porewater water isotope assays using the direct H2O(liquid)–H2O(vapor) equilibration method

The hydrogen and oxygen stable isotopes of water (δ2H and δ18O) are powerful tracers for studying subsurface water flow processes, but the extraction of porewater from unsaturated soil is complex and laborious. The direct liquid–vapor equilibration method (DLVE) for isotope analysis overcomes this challenge by analyzing headspace vapor in isotopic equilibrium with the porewater under closed system conditions. However, the effect of the equilibration time, soil texture, and porewater saturation on isotopic results is not fully understood yet. We tested three differently textured, disaggregated soils (sandy, silty loam and clay) to assess how the equilibration time is impacted by (i) porewater saturation (100%, 80%, 60%, and 40%), and (ii) soil surface area. For all tests, the water loss through diffusion was negligible (<0.3%). The experiments showed that for disaggregated sandy soil, 24 h was a sufficient isotopic equilibration time regardless of water saturation level. Similarly, 24 h was sufficient for kaolinite samples with 100% saturation exhibiting little isotopic variance even after 168 h of equilibration. For saturated silty loam with 2% organic carbon content, 96 h was the optimal equilibration time, whereas saturated silty loam with 4% organic carbon content did not reach isotopic equilibrium by 168 h. The optimal equilibration time increased depending on whether soil samples were disaggregated or kept in a core cutter. Inconclusive results for silty soils with organic carbon revealed the need to further investigate the possible influence of organic carbon on the DLVE method.

Pleistocene-Holocene Monogenetic Volcanism at the Malko-Petropavlovsk Zone of Transverse Dislocations on Kamchatka: Geochemical Features and Genesis

The Malko-Petropavlovsk zone of transverse dislocations (MPZ) was formed on the extension of the deep Avachinsky transform fault in perpendicular relation to the subduction trench. It is a natural boundary between variously aged slabs in Kamchatka (103–105 Ma under Southern Kamchatka and 87–92 Ma under the Eastern volcanic belt). Monogenetic cinder cones in the MPZ are randomly distributed along these long-lived rupture zones. Here we present new geochemical and isotopic results of monogenetic volcanism in the MPZ. Based on whole rock and trace element geochemistry, Pb-Sr-Nd isotopic ratios of monogenetic cinder cone magmas were shown to tap the enriched mantle source (low 143Nd/144Nd isotopic ratios (0.512959–0.512999), and changed as 87Sr/86Sr (0.703356–0.703451) and 206Pb/204Pb (18.30–18.45), 208Pb/207Pb (38.00–38.12) isotopic ratios). High Nb/Yb and La/Yb ratios, without significant inputs of the slab’s components (the lowest Ba, Th content), indicate decompression melting predominately. Calculations of the pressure (9–11 kbar) and temperature (1160–1240 °C) conditions using a glass thermobarometer suggest that magma of monogenetic cinder cones resided near the Moho boundary prior to eruption. This correlates with the crustal discontinuity under the MPZ according to geophysical observations (converted-wave seismic exploration and magnetotelluric sounding). The majority of well-preserved monogenetic cinder cones were formed in Holocene, after the last glaciation, but eruptions were not observed historically. This, however, suggests that similar eruptions in the MPZ may occur in the future. Given that the MPZ hosts major population centres of Kamchatka (Petropavlovsk, Elizovo, Vilyuchinks, and Paratunka: ~ 250,000 people or ~ 80% of the whole Kamchatkan population live in the major cities on the coastline of the MPZ), we highlight the urgent need to install a continuous monitoring system around the MPZ cones, geophysical investigation, and more serious attention from the local government and scientists. In particular, a detailed study of the MPZ regarding age, volume, and volcanic hazard assessment (pyroclastic vs extrusive) will help reduce potential risks of eruptions from monogenetic volcanoes for humans and infrastructures.

Oxygen isotopes of calcite precipitated at high ionic strength: CaCO3-DIC fractionation and carbonic anhydrase inhibition

Background electrolytes affect calcite precipitation and dissolution rates and hence have the potential to impact kinetic isotope fractionation between calcite and the dissolved inorganic carbon (DIC) species. We grew inorganic calcite from NaCl-CaCl2 solutions (T = 25 °C, pH = 8.3, and crystal growth rate = 10−6.3 ± 0.3 mol m−2 s−1) to test for potential ionic strength effects on the oxygen isotope fractionation between calcite and an isotopically equilibrated inorganic carbon pool (αc/EIC). Calcite was grown in the presence of the enzyme carbonic anhydrase from bovine erythrocytes (bCA) to promote isotopic equilibration of the DIC pool.No evidence of an ionic strength effect on αc/EIC was found for NaCl concentrations up to 0.35 M (1000lnαc/w = 28.0 ± 0.1; n = 7). For experiments conducted with [NaCl] > 0.35 M, the DIC pool could not be maintained in isotopic equilibrium with water due to the inhibitory effect of NaCl on bCA. The use of other types of CA may be required to maintain isotopic equilibration of DIC in solution with ionic strength close to or above that of seawater.The oxygen isotope results were modeled successfully with an isotopic box model for a CO2-fed solution that tracks the isotopic composition of each DIC species and CaCO3. The experimental and modeling results suggest that the efficacy of bCA decreases exponentially with increasing [NaCl]. We quantify the salt effect on the quantity kcat/KM, which relates the catalyzed rate constant for CO2 hydration to the concentration of bCA. The salt effect can be implemented in models of biomineralization with potential to extend our knowledge of oxygen isotope vital effects in marine organisms.

Isotopic tracing and quantitative assessment of rainwater in a separate sewer system in Tiszavasvári, Hungary

The hydrological processes that commonly occur within the sewer system i.e., rainwater percolation or groundwater infiltration, can be easily described applying water isotopes. This study investigates the potential of tritium and stable isotope composition (δ2H and δ18O) of water for tracing rainwater entering urban sewer and estimating the amount. The work consists of collecting and analyzing wastewater and rainwater samples over a six-day-long period including a 30-min-long rainfall event, and then applying the isotopic results to determine the mixing ratios in the sewer pipes and the sensitivity of the applied tracing methods. Results reveal that the isotopic composition of wastewater reacts to inflowing rainwater sensitively: detectable flow rate increase resulting from rainfall is 0.62 m3h-1 for tritium, 2.49 m3h-1 for δ18O and 1.25 m3h-1 for δ2H. While applying variation of discharge, these values are 12.15 m3h-1 and 18.91 m3h-1 in daytime and nighttime, respectively. Due to the more positive stable isotope values of precipitation in the summer half-year, isotopic difference of rainwater and groundwater (being less enriched) is more notable, subsequently, traceable amount of parasitic rainwater in case of the examined area is lower than in the winter half-year. In case of groundwater recharged under cold climate conditions sampling should be carried out in summer in the night hours, after an at least three-day-long dry period. Though, all three isotopic tracers applied in this study proved to be suitable to detect small amount of parasitic precipitation, tritium came out as the most sensitive one.

Geochemistry and petrogenesis of ca. 2.1 Ga meta-mafic rocks in the central Jiao–Liao–Ji Belt, North China Craton: A consequence of intracontinental rifting or subduction?

As one of the global 2.0–1.8 Ga continent-to-continent collisional orogens that welded the Supercontinent Columbia or Nuna, the Jiao–Liao–Ji Belt (JLJB) in the North China Craton was formed through ca. 1.90–1.85 Ga collision between the Longgang and Nangrim Blocks. However, the tectonic process before the final collision remains highly controversial. Some people insisted that during 2.2–2.1 Ga the JLJB was in a back-arc area of a subduction regime. In contrast, some other people proposed that ca. 2.2–2.1 Ga represented a continental rifting stage instead of subduction. To tackle this controversy, the coeval mafic rocks and their petrogenesis become the key hints. Therefore, we implemented synthetic petrological, geochronological, geochemical, zircon Hf and the whole rock Sr–Nd isotopic studies for the newly mapped meta-mafic rocks from the central JLJB. Zircon U–Pb dating results revealed that they were emplaced at ca. 2133–2099 Ma and experienced subsequent collision-related regional metamorphism at ca. 1879–1852 Ma. Geochemically, they are sub-alkaline basalts and contain moderate SiO2 and high concentrations of MgO, total Fe2O3, Ni, and V. They are enriched in light rare earth elements (LREE) and large-ion lithophile elements (LILE; e.g., Ba, Sr and K), and are depleted in heavy rare earth elements (HREE) and high field strength elements (HFSE; e.g., Nb and Ta). Geochemical features show largely affinity to the enriched mid-ocean ridge basalts. Isotopic results show low 87Sr/86Srt ratios (low to 0.676869), positive εNd(t) values (+0.50 to +2.45) and εHf(t) values (+0.04 to +9.81). The parental magmas of ca. 2.1 Ga meta-mafic rocks were most likely derived from the partial melting of the depleted asthenospheric mantle with contamination of crustal material. Associated with the regionally developed A-type and adakitic granites, as well as the bimodal volcanic rocks throughout the JLJB, we proposed that the Longgang and Nangrim Blocks were initially broken apart through an intracontinental rifting that was triggered by delamination of an old thickened lithosphere at ca. 2.2–2.1 Ga, before they were finally collided with each other at ca. 1.90 Ga.

Carcinogenic risk assessment, health endpoint and source identification of heavy metals in Mahshahr, Iran

Heavy metals (HM) are one of the main agents that threaten human health. The most important source that release heavy metals (As, Cd, Cu, Cr, Pb, Ni, V, and Zn) in the environment is Petrochemical industries. This study was investigated the carcinogenic risk assessment, health endpoint and source identification of heavy metals. Samples were taken from the different regions: parks, residential, industrial, administrative and central and high traffic areas in Mahshahr, southwest, Iran and investigate the environmental impacts of the studied petrochemical industry. Measurement of heavy metals performed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Results of the PCA showed that As had a different source than other heavy metals, which can be owing to numerous human and industrial activities in the region. Based on the results, the Igeo factor was assessed at high levels for Ni, Pb, and Cd metals. Moreover, the results demonstrated high intensities of pollution for Pb, Zn, Cd, and Ni metals under the application of PI and IPI indices, and for Ni, Pb, and Cd metals under the application of the EF index. The index of the risk index (RI) average of the studied metals represented a significant risk for Ni, Cr and As metals on children and adults. In addition, Pb isotopic results showed high levels of 208Pb/206Pb to 207Pb/206Pb, which indicated that the increase of the Pb isotope in the studied region was concerned with petrochemical activities of human origin. In this study, it was found that the soils of the Mahshahr port industrial zone have high anomalies of some metals, especially Ni, Pb, Zn and Cd, which were due to the growth of traffic and economic and industrial activities in the region. However, heavy metals such as As and V exhibited the lowest risk and very low pollution in all indicators.

Hydrogeochemical and isotopic evaluation of VOC commingled plumes in a weathered fractured bedrock aquifer treated with thermal and bioremediation

Chlorinated ethanes and ethenes isotopic analyses in groundwater and hydrogeochemical results from a former industrial area in Sao Paulo (Brazil) were used to confirm the existence and allow further characterization of source areas and their commingled plumes, both before and after thermal and bioremediation treatments. Prior to full scale remediation, a recently identified off-site source area with unknown history and limited access for further intrusive works presented lower δ13C values (−6.5‰ to −1.8‰ for 1,2-DCA) than the downgradient on-site source area (+8.6‰ to +20.0‰). Intermediate δ13C values for 1,2-DCA were identified further downgradient from the sources, within commingled plumes patterns. The isotope and concentration results show the typical degradation patterns associated with biotic reductive dechlorination for chlorinated ethenes and dihaloelimination for 1,2-DCA. Results following remediation treatments show further levels of isotopic enrichment, for chlorinated ethenes and chlorinated ethanes in the tropically weathered and deeper fractured bedrock (gneisses) groundwater. Hydrogeochemical results, isotopic mass balance and Carbon-Chlorine isotope slopes data are coherent with remediation treatment and a complex commingled plume setting. The results of this study confirmed the Temporal Conceptual Model proposed by Hart et al. (2021) and identified the need for further studies to evaluate isotopic dynamics under thermal remediation, including thermal-induced hydrolysis processes.

Rastreability of bovine meat and bone meal using the stable isotope technique in egg production

The present study aimed to verify whether the inclusion of other ingredients in the diet of laying hens could interfere with the traceability of bovine meat and bone meal (BMBM) in eggs through stable carbon and nitrogen isotope analysis. Two hundred and fifty-six white laying hens were used and randomly distributed into eight treatments composed of: CONTROL: control diet; GLUTEN: control diet + corn gluten; YEAST: control diet + yeast; GLUTEN + YEAST: control diet + corn gluten + yeast; BMBM: control diet + 4.5 % BMBM; BMBM + GLUTEN: control diet + corn gluten + 4.5 % BMBM; BMBM + YEAST: control diet + yeast + 4.5 % BMBM; BMBM + GLUTEN + YEAST: control diet + corn gluten + yeast + 4.5 % BMBM. The isotopic results were subjected to multivariate analysis of variance (MANOVA) and LDA multivariate linear discriminant analysis. At 28 days, the eggs of the birds given diets without the addition of BMBM differed from the CONTROL group. The yolks showed that all treatments were significantly different from the CONTROL, and at 56 days, all eggs and egg yolks were different from the CONTROL. At 28 days, albumen was significantly different for all CONTROL experimental treatments; however, at 56 days, the YEAST treatment showed no difference from the control. Thus, it was concluded that even with the addition of other ingredients, the isotope technique is still able to detect the BMBM in eggs.

Water stable isotopes in snow along a traverse of the West Antarctic Ice Sheet: insights into moisture origins, air-masses distillation history, and climatic value.

This study investigated the water isotopic content (δ18O, δD, d-excess) of the surface snow along a 995 km traverse over the West Antarctic Ice Sheet from the Möller Ice Stream - Institute Ice Stream to the upper reaches of the Pine Island Glacier drainage basin. The purpose of this study was to evaluate the climatic record preserved in the snow. We analyzed 92 surface samples (~0.15-0.20 m deep), retrieved during 2014/2015 austral summer from every ~10 km along the traverse route, using the laser spectroscopy technique. We computed the isotopic-geographical characteristics and spatial co-isotopic empirical relationships and compared the isotopic results with the tropospheric mean annual temperature and air mass trajectories. Our isotopic results were sensitive to capturing the well-known climatic asymmetry between the Amundsen-Bellingshausen Sea (ABS; which receives more influence from warmer (oceanic) air masses) and Weddell Sea (WS; more influenced by colder (continental) air masses) sectors. Further, the spatial distribution of δs and d-excess and the co-isotopic relationships reflect two preferential fractionation paths: one from the coast of the ABS sector to the WS sector, and another from the coast of the WS sector to the inland. The Pacific Ocean is confirmed as the primary source of moisture.