Acta Geochimica最新文献

{"title":"Alkaline igneous rocks, a potential source of rare metals and radioactive minerals: Case study at Amreit area, south Eastern Desert, Egypt","authors":"Baaha M. Emad","doi":"10.1007/s11631-024-00713-2","DOIUrl":"10.1007/s11631-024-00713-2","url":null,"abstract":"<div><p>Alkaline igneous rocks represent one of the most economically important resources of radioactive minerals and rare metals. New field observations and petrographic studies are integrated with whole-rock geochemical analyses and Gamma ray spectroscopy data of alkaline rocks associated with the Amreit complex. The fieldwork was achieved by the collection of more than forty samples from alkaline granites and alkaline syenites. The youngest rocks cropping out in the study area are the cogenetic alkaline rocks, ranging from alkaline granite to alkaline syenite. These alkaline rocks are composed essentially of K-feldspar, alkali amphiboles (arfvedsonite), and sodic pyroxene, with accessories such as zircon, apatite, and ilmenite. Mineral characterization of the highly radioactive zones in both alkaline granite and alkaline syenite displays enrichment in monazite, thorite, zircon, ferro-columbite, xenotime, and allanite minerals. Geochemical analyses indicate that the Amreit rocks are alkaline with peralkaline affinity and have high concentrations of total alkalis (K₂O + Na₂O), large ion lithophile elements (LILEs; Ba and Rb), high field strength elements (HFSEs; Y, Zr and Nb), rare earth elements (REEs) and significantly depleted in K, Sr, P, Ti, and Eu, typically of post-collision A-type granites. Typically, the Amreit alkaline igneous rocks are classified as within plate granites and display A2 subtype characteristics. The fractionation of K-feldspars played a distinctive role during the magmatic evolution of these alkaline rocks. The geochemical characteristics indicate that the studied alkaline igneous rocks which were originated by fractional crystallization of alkaline magmas were responsible for the enrichment of the REE and rare metals in the residual melt. The high radioactivity is essentially related to accessory minerals, such as zircon, allanite, and monazite. The alkaline granite is the most U- and Th-rich rock, where radioactivity level reaches up to 14.7 ppm (181.55 Bq/kg) eU, 40.6 ppm (164.84 Bq/kg) eTh, whereas in alkaline syenite radioactivity level is 8.5 ppm (104.96 Bq/kg) eU, 30.2 ppm (122.61 Bq/kg) eTh. These observations suppose that these alkaline rocks may be important targets for REEs and radioactive mineral exploration.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"189 - 214"},"PeriodicalIF":1.4,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biogeochemical behavior of 210Po in the aquatic ecosystem of the North Crimean Canal and adjacent irrigated soils","authors":"A. A. Korotkov,&nbsp;N. Yu. Mirzoeva,&nbsp;O. N. Miroshnichenko,&nbsp;I. N. Moseichenko","doi":"10.1007/s11631-024-00721-2","DOIUrl":"10.1007/s11631-024-00721-2","url":null,"abstract":"<div><p>The main objectives of this study were to investigate the distribution features of the ²¹⁰Po in abiotic (water and bottom sediments) and biotic (zooplankton, mollusks, fish) components of the North Crimean Canal (NCC) aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed ²¹⁰Po. The samples were processed using standard radiochemical methods accepted in international practice. The activity of ²¹⁰Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex (ORTEC-AMETEK, USA). The measurement error did not exceed 20%. Activity concentration of ²¹⁰Po in the studied objects decreased in the following rank: suspended matter (73.6 Bq/kg d.w.) &gt; soils (32.5 Bq/kg d.w.) ≈ bottom sediments (32.1 Bq/kg d.w.) &gt; mollusks (23.4 Bq/kg w.w.) &gt; fish (6.4 Bq/kg w.w.). The ²¹⁰Po distribution coefficient (<i>K</i>_d) values in water between suspended matter and its dissolved parts varied within the 1.4 × 10⁴–1.4 × 10⁵ L/kg range. The concentration factors (CF) of ²¹⁰Po for hydrobionts of the NCC were in the range 10³–10⁴ L/kg. The calculated absorbed radiation doses from ²¹⁰Po alpha radiation for the hydrobionts of the North Crimean Canal were significantly below the recommended dose limits.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"314 - 324"},"PeriodicalIF":1.4,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141640292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The lithology and composition of lunar mantle modified by ilmenite bearing cumulate: A thermodynamic model","authors":"Wei Huang,&nbsp;Wei Du","doi":"10.1007/s11631-024-00718-x","DOIUrl":"10.1007/s11631-024-00718-x","url":null,"abstract":"<div><p>Due to their high density, the ilmenite-bearing cumulates (IBC) (with or without KREEP) formed during the late-stage lunar magma ocean solidification are thought to sink into the underlying lunar mantle and trigger lunar mantle overturn. Geophysical evidence implied that IBC may descend deep inside the Moon and remain as a partially molten layer at the core-mantle boundary (CMB). However, partial melting may have occurred on the mixed mantle cumulates during the sinking of IBC/KREEP and the silicate melt may be positively buoyant, thus preventing the IBC/KREEP layer from sinking to the CMB. Here, we perform thermodynamic simulation on the stability of lunar mantle cumulates at different depths mixed with different amounts of IBC/KREEP from an updated LMO model. The modeling results suggest that the sinking of IBC/KREEP will cause at least 5 wt% partial melting in the shallow (~ 120 km) and a much larger degree of partial melting in the deep lunar mantle (~ 420 km). Due to the density contrast with the surrounding mantle, IBC/KREEP-bearing melts could potentially decouple under certain conditions. The modified lunar mantle by sinking of IBC/KREEP can better explain the formation of different kinds of lunar basaltic magma than the primary lunar mantle formed through differentiation of lunar magma ocean. Sinking of IBC/KREEP back into the lunar mantle may introduce plagioclase, clinopyroxene, garnet, and incompatible radioactive elements into the deep lunar mantle, which will further affect the thermal and chemical evolution of the lunar interior.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 5","pages":"856 - 875"},"PeriodicalIF":1.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141654823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Features of the spatial and seasonal distribution of hydrocarbons in water of the North Crimean Canal, Crimea","authors":"O. V. Soloveva,&nbsp;E. A. Tikhonova,&nbsp;N. Yu. Mirzoeva","doi":"10.1007/s11631-024-00719-w","DOIUrl":"10.1007/s11631-024-00719-w","url":null,"abstract":"<div><p>The North Crimean Canal is a watercourse originating from the Kakhovka Reservoir and flowing into the Crimean Peninsula. The canal is an important source of drinking water supply and is also used to irrigate agricultural lands and fill fish farms. Due to its location, in recent years its functioning has not been stable, and the processes occurring along the canal have been poorly studied. In this study, we determined the content (with a safety assessment), features of spatial and seasonal distribution, and potential sources of hydrocarbons in the water of the North Crimean Canal, Crimea. During the study period (from March to November 2023) in the primary canal, the content of aliphatic hydrocarbons did not exceed sanitary standards (0.05 mg·L⁻¹). Their increased concentrations in the secondary canals could be associated with the input of organic substances into the canal water as it moves across the Crimean Peninsula. The composition of <i>n-</i>alkanes had temporal and spatial variability. In the period from spring to autumn, the content of autochthonous compounds decreased sharply. The share of allochthonous compounds increased as a consequence of the natural processes. The analysis of biogeochemical markers showed that autochthonous compounds produced by phytoplankton predominated in the spring–summer period. Subsequently, they had less importance, and the main share was accounted for allochthonous <i>n-</i>alkanes.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"247 - 259"},"PeriodicalIF":1.4,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141656572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and petrogenesis of magnesian high-K granitoids from Bundelkhand Craton, Central India: New insights into crustal evolution","authors":"Shailendra K. Prajapati,&nbsp;Meraj Alam,&nbsp;Parashar Mishra,&nbsp;Hemant Kumar","doi":"10.1007/s11631-024-00717-y","DOIUrl":"10.1007/s11631-024-00717-y","url":null,"abstract":"<div><h3>Background</h3><p>The Bundelkhand Craton is significant for preserving the multiphase granitoids magmatism from Paleoarchean to Neoarchean periods. It consists of a variety of granite rocks, including TTGs, sanukitoids, and high-K granitoids. This study presents geochemical characteristics of high-silica (68.97 wt.%–73.99 wt.%), low-silica (58.73 wt.%–69.94 wt.%), and high K₂O (2.77 wt.%–6.16 wt.%) contents of granitoids.</p><h3>Objective</h3><p>The data on Bundelkhand Craton's granitic magmatism and geodynamics is not sufficiently robust. Geochemical data from this study will be used to further understand the origin, source, and petrogenesis of granitoid rocks and their implications for the evolution of geodynamics.</p><h3>Methodology</h3><p>Twenty-one samples were collected and analyzed for major, trace, and REE elements. Major elements were measured using X-ray fluorescence spectrometry (XRF), and trace and REE elements were analyzed by ICP-MS. Standard procedures from the Geological Survey of India were followed.</p><h3>Results</h3><p>The geochemical analysis presents high-silica (68.97-73.99 wt. %), low-silica (58.73-69.94 wt. %), and high K2O (2.77-6.16 wt. %) contents in granitoids, classified as granite-granodiorite. The rocks are calcic to calcalkalic, magnesian, and range from peraluminous to metaluminous composition. REE patterns showed strong LREE enrichment relative to HREEs, with prominent negative Eu anomalies corresponding to earlier plagioclase fractionation. Multi-element patterns revealed negative anomalies in Nb, Sr, P, and Ti and positive anomalies in Pb.</p><h3>Conclusion</h3><p>The geochemical signatures attributed to the post-collisional magma generation and continental crustal contamination. The studied rocks show A-type and A2-type lineage, suggesting they originated from the melting of continental crust during transitional/post-collisional tectonic activity. The formation of hybrid granitoids in the Bundelkhand Craton is connected to the fractionation of hybrid magmas in shallow-seated magma chambers during these tectonic processes.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"36 - 58"},"PeriodicalIF":1.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and mineral chemistry of granitic rocks from west Wadi El Gemal area, southern Eastern Desert of Egypt: Indicators for highly fractionated syn- to post-collisional Neoproterozoic felsic magmatism","authors":"Hesham Mokhtar,&nbsp;Adel A. Surour,&nbsp;Mokhles K. Azer,&nbsp;Minghua Ren,&nbsp;Amir Said","doi":"10.1007/s11631-024-00714-1","DOIUrl":"10.1007/s11631-024-00714-1","url":null,"abstract":"<div><p>Leucogranite, pegmatite, and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their petrogenesis. These rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield (ANS) during the Late Neoproterozoic. On a petrographic basis, the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite, syenogranite, and alkali feldspar granite. The analyses of muscovite, biotite, garnet, and apatite reveal the magmatic nature of the studied leucogranite. The investigated leucogranite, pegmatite, and aplite are alkali-calcic, calc-alkaline, and peraluminous. The peraluminous nature of these rocks is evidenced by using the chemical analyses of biotite. These studied rocks show a slight enrichment in light rare-earth elements (LREEs) and large-ion lithophile elements (LILE, especially Rb and Th), with an insignificant depletion of heavy rare-earth elements (HREEs). On a geochemical basis, the leucogranite, pegmatite, and aplite in the study area crystallized from multiple-sourced melts that include mafic, metagraywake, and pelitic. They were derived from melts generated at crystallization temperatures around 568–900 °C for leucogranite, 553–781 °C for pegmatite, and 639–779 °C for aplite based on the Zr saturation geothermometers, and at a pressure around 0.39–0.48 GPa, i.e. shallow depth intrusions. The studied felsic rocks have strong negative Eu anomalies, which are very consistent with an upper crust composition, indicating fractionation of feldspar cumulates. Also, they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional crystallization. Integration of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn- to post-collisional granite, pegmatite, and aplite. An evolutionary three-stage model is presented to understand late magmatism in the ANS in terms of a geodynamic model. Such a model discusses the propagation of felsic magmatism in the ANS during syn-collisional to post-collisional stages.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"163 - 188"},"PeriodicalIF":1.4,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141673228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fresh insights into the onset of big mantle wedge beneath the North China Craton","authors":"Yingpeng Wang,&nbsp;Xuance Wang,&nbsp;Wen Zhang,&nbsp;Xiaowei Yu,&nbsp;Ligong Wang,&nbsp;Jinhui Wang,&nbsp;Peigang Zhu,&nbsp;Yongbin Wang","doi":"10.1007/s11631-024-00716-z","DOIUrl":"10.1007/s11631-024-00716-z","url":null,"abstract":"<div><p>The onset of the big mantle wedge (BMW) structure beneath the North China Craton remains debated. Research on the genesis of Late Mesozoic granites associated with gold deposits in the Jiaodong Peninsula above the BMW could provide fresh insights into this question. The monzogranite from the Zhaoxian-Shaling gold district was intruded during 154–148 Ma. This I-type granite has high-K calc-alkaline and metaluminous characteristics. The monzogranite formed at medium temperatures (718–770 °C) and was generated in a thickened lower crust at depths within the stability field of garnet. The monzogranite's high zircon Ce⁴⁺/Ce³⁺ and Eu_N/Eu_N* values and low FeO^T/MgO ratios, suggest that it formed in a high oxygen environment. Its variable ε_Hf(t) values with T_DM2 of 1.93–2.87 Ga imply that it originated from the melting of ancient crust basement, with contributions from mantle-derived materials. The granite's enrichment in LREEs and LILEs, and depletion in HREEs and HFSEs, along with its trace element tectonic discrimination diagrams and medium Sr/Y, indicate an adakite affinity in an active continental margin setting. The transition from S-type granites to I-type granites and finally to A-type granites observed in the eastern part of North China Craton suggests a shift in the tectonic environment from compression to extension. This change is also reflected in the transition from flat subduction to steep subduction. Therefore, the monzogranite was formed in a tectonic transition setting triggered by a change in the subduction angle of the Paleo-Pacific Ocean slab during the Late Jurassic. This event may have marked the initiation of the BMW above the North China Craton.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"145 - 162"},"PeriodicalIF":1.4,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141687288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogical and geochemical characterization of the Wadi Natash volcanic field (WNVF), Egypt: Alkaline magmatism in a Late Cretaceous continental rift system","authors":"Adel A. Surour,&nbsp;Ahmed A. Madani,&nbsp;Mohamed A. El-Sharkawi","doi":"10.1007/s11631-024-00702-5","DOIUrl":"10.1007/s11631-024-00702-5","url":null,"abstract":"<div><p>The Wadi Natash volcanic field (WNVF) in the south of the Eastern Desert of Egypt is a typical example of well-preserved intraplate alkaline magmatism during the Late Cretaceous, i.e., prior to the Oligo-Miocene Red Sea rift. We compiled stratigraphic sections at two sectors; namely East Gabal Nuqra and West Khashm Natash (WKN) where the volcanic flows are intercalated with the Turonian Abu Agag sandstone with occasional paleosols when volcanic activity is intermittent. Peridotite mantle xenoliths are encountered in the first sector whereas flows in the second sector are interrupted by trachyte plugs and ring dykes. On a geochemical basis, the mafic melt originating from the lithospheric mantle beneath the WNVF practiced ~ 5% partial melting of phlogopite-bearing garnet peridotite. Basalts dominate in the two sectors and highly evolved (silicic) rocks are confined to the WKN sector. Rejuvenation of ancient Precambrian fractures following the NW–SE and ENE-WSW trends facilitated the ascend of Late Cretaceous mantle-derived alkaline magma. Structurally, the WNVF developed at the eastern shoulder of the so-called “Kom Ombo-Nuqra-Kharit rift system” that represents a well-defined NW-trending intracontinental rift basin in the southern Eastern Desert. In such a structural setup, the Natash volcanic are confined to half-grabens at the East Gabal Nuqra sector whereas the West Khashm Natash sector is subjected to extensional stresses that propagated eastwards. The WNVF is a typical example of fluvial clastics (Turonian) intercalation with rift-related alkaline volcanic rocks in northeast Africa.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 6","pages":"1169 - 1191"},"PeriodicalIF":1.4,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry of Neoproterozoic metavolcanic rocks from the Tahtai Logomiti area, Tigrai, Northern Ethiopia: Implication for petrogenesis and tectonic settings","authors":"Azeb Gebremicale,&nbsp;Mulugeta Alene,&nbsp;Teklay Gidey","doi":"10.1007/s11631-024-00712-3","DOIUrl":"10.1007/s11631-024-00712-3","url":null,"abstract":"<div><p>The Tahtai Logomiti area is characterized by metavolcanic and metavolcaniclastic interbedded with clastic and carbonate metasedimentary rocks of Neoproterozoic age. New geological, petrographic, major, and trace elements data were used to evaluate the metamorphism, petrogenesis, and paleo-tectonic setting of the area. The field and petrographic observation indicate that the area has undergone greenschist facies metamorphism. Based on mineralogy and geochemical attributes, these metavolcanic rocks are classified as basalt, basaltic-andesite, andesite, and dacite. The moderate degrees of light rare earth element (LREE) enrichment, flat heavy rare earth element (HREE) pattern, and low Nb/Y ratio, represent shallow mantle sources. In addition to that, the TiO₂/Yb vs. Nb/Yb diagram, high (La/Yb)N ratio (&gt; 3.44), indicates shallow melting and depleted magma sources. However, the high ratios of (Th/Ta) &gt; 3.8, (La/Ta) &gt; 38, and low ratios of (Th/La) &lt; 1, (Nb/La) &lt; 1, and high Pb content would indicate crustal contamination of the magma. The discrimination diagram and trace element ratios (Nb/Y, La/Sc, La/Y, and La/Th) indicate that the metavolcanic rocks have a calc-alkaline affinity. In addition, the Zr-Nb-Y and Th-Hf-Ta plots show that the rocks formed under a volcanic-arc setting. The general petrological and geochemical characteristics of the Tahtai Logomiti metavolcanic rocks suggest that the area is associated with subduction-related arc accretion of the Arabian Nubian Shield.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"128 - 144"},"PeriodicalIF":1.4,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the impact of climate change on dissolved oxygen using a flow field ecosystem model that takes into account the anaerobic and aerobic environment of bottom sediments","authors":"Jinichi Koue","doi":"10.1007/s11631-024-00711-4","DOIUrl":"10.1007/s11631-024-00711-4","url":null,"abstract":"<div><p>This study examines the potential impacts of climate change on Lake Biwa, Japan’s largest freshwater lake, with a focus on temperature, wind speed, and precipitation variations. Leveraging data from the IPCC Sixth Assessment Report, including CCP scenarios, projecting a significant temperature rise of 3.3–5.7 °C in the case of very high GHG emission power, the research investigates how these shifts may influence dissolved oxygen levels in Lake Biwa. Through a one-dimensional model incorporating sediment redox reactions, various scenarios where air temperature and wind speed are changed are simulated. It is revealed that a 5 °C increase in air temperature leads to decreasing 1–2 mg/L of dissolved oxygen concentrations from the surface layer to the bottom layer, while a decrease in air temperature tends to elevate 1–3 mg/L of oxygen levels. Moreover, doubling wind speed enhances surface layer oxygen but diminishes it in deeper layers due to increased mixing. Seasonal variations in wind effects are noted, with significant surface layer oxygen increases from 0.4 to 0.8 mg/L during summer to autumn, increases from 0.4 to 0.8 mg/L in autumn to winter due to intensified vertical mixing. This phenomenon impacts the lake’s oxygen cycle year-round. In contrast, precipitation changes show limited impact on oxygen levels, suggesting minor influence compared to other meteorological factors. The study suggests the necessity of comprehensive three-dimensional models that account for lake-specific and geographical factors for accurate predictions of future water conditions. A holistic approach integrating nutrient levels, water temperature, and river inflow is deemed essential for sustainable management of Lake Biwa’s water resources, particularly in addressing precipitation variations.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"11 - 22"},"PeriodicalIF":1.4,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11631-024-00711-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}