Abstract:This paper is the result of mineral exploration engineering. Objective The faded alteration of uranium–bearing rock series in the redbed is closely related to reductive alteration, and the analysis of the characteristics of faded alteration and its genetic fluid is of great significance for understanding the uranium ore–forming fluids and ore–forming mechanism. Methods This study is based on analyzing the sedimentary characteristics and faded alteration characteristics of sandstones in Luohe Formation by means of core logging, element geochemical test, electron microscope scanning, electron probe analysis, XRF scanning and core infrared spectrum scanning. Results The sandstones in the Luohe Formation are basically formed in aeolian sedimentary with oxidation conditions mineral assemblages enriched in uranium minerals, pyrite and gypsum but little trivalent iron oxides, and uranium and sulfur elements show obvious migration. Then, the redox state of sandstone and the correlation between uranium mineralization and faded alteration were discussed. Conclusions The main body of Luohe Formation sandstone was formed in aeolian deposits under oxidation conditions, and its color, Fe₂O₃/FeO, Th/U and Cu/Zn reflect that the environment has been changed from oxidation to reduction with the increase of sandstone faded degree. The characteristics of the consistency between faded alteration and uranium mineralization in Luohe Formation in space, mineral association and redox state suggest that their genesis is related to the same reducing fluid.

Abstract:This paper is the result of environmental geological survey engineering. Objective To investigate the distribution characteristics of heavy metals and provide a scientific basis for local characteristic agricultural development, comprehensive tourism, and soil heavy metal pollution control. Methods Through geological investigation, the soil parent material was identified, and topsoil samples were collected. Soil environmental quality evaluation was carried out based on the distribution characteristics and enrichment degree of element content. The degree of heavy metal pollution was evaluated using the ground accumulation index method. The Hakanson ecological risk index method was used to identify the degree of potential ecological risk in the study area. Furthermore, Pearson correlation analysis and cluster analysis were employed to quantitatively determine the main sources of different heavy metals. Results The average values of Cr and Pb in the soil of the Beizhen agricultural area were lower than the background values of the Liaohe River Basin in Liaoning Province. The enrichment degree of heavy metals in the topsoil, from high to low, was Hg > As > Cd > Pb > Zn > Cu > Cr > Ni. The soil quality in the study area is generally good. The proportion of Cd, Cu, and Zn contents exceeding the risk screening values in the exceeding standard samples was 45.56%, 29.11%, and 11.47%, respectively, accounting for 86.12% of the total number of exceeding standards. The evaluation results of heavy metal pollution showed that As and Cd were in a mildly polluted state, most heavy metals in soil samples were in no to mild pollution, and only Hg elements had strong to extremely strong pollution at individual sampling points. The order of potential ecological risk of single indices from high to low is Hg > Cd > As > Cu > Ni > Pb > Cr > Zn. The distribution range of the potential ecological risk comprehensive index (RI) of surface soil in the whole region is 29.7 to 2358.16, with an average value of 141.9, primarily indicating low risk, followed by moderate risk. The results of correlation analysis and cluster analysis show that Ni, Cr, As, and Pb are mainly affected by the natural weathering of the parent rock, while Cu, Zn, Cd, and Hg are influenced by agricultural production, industrial production, transportation, and even construction activities. Conclusions The enrichment of substances produced by the unreasonable application of agricultural substances, atmospheric deposition, industrial production, domestic garbage, and coal combustion in the soil may pose pollution risks to the ecological environment quality of the study area. In the future, it is necessary to strengthen the monitoring and research on the enrichment trend of Hg, Cd, Cu, and Zn elements in different plots.

Abstract:This paper is the result of environmental geological survey engineering. Objective This paper collected 34 surface soil samples to analyze and determine the concentrations of eight heavy metal, including Hg, Cd, As, Pb, Cu, Cr, Zn, and Ni. The objective was to characterize the heavy metal pollution in the soil around a gold mine, identify the sources of heavy metals in the soil, and conduct a risk assessment. Methods Correlation analysis and principal component analysis were used to explore the sources of heavy metals in the soil. Single pollution evaluation and geo–accumulation index method were employed to determine the degree of pollution. Potential ecological risk assessment and human health risk assessment methods were utilized to evaluate the risks. Results (1) Only three point source pollutions were found in the study area: one for Hg contamination and two for Cd contamination. (2) Nickel, chromium, and arsenic mainly originated from soil parent materials, while lead, cadmium, zinc, and mercury primarily came from mining activities. Copper was derived from both soil parent materials and agricultural activities. (3) Some localized areas demonstrated high potential ecological risks, mainly due to Hg and Cd, while other elements posed minimal risks. (4) Human health risk assessment indicated that the heavy metal elements in the soil did not pose significant health risks to humans. Conclusions The soil around the gold mine was influenced by mining activities and exhibited localized pollution, albeit at a low level. The risks were manageable, but monitoring and assessment of heavy metals in this area should be strengthened.

Abstract:This paper is the result of environmental geological survey engineering. Objective Natural geological carbon sinks mostly consist of soil and karst carbon sinks, and the main form of carbon’s participation in the carbon cycle in soil is organic carbon. Therefore, the study of topsoil organic carbon has great significance for increasing soil carbon sink and achieving the "carbon peaking and carbon neutrality" goal. Methods Based on the data of a multi–objective regional geochemical survey, this paper analyzed the spatial distribution of topsoil organic carbon density in Chongqing with the geostatistical method, studied the influencing factors and importance of soil organic carbon density by one–way ANOVA and classification regression tree and evaluated the carbon sequestration and emission reduction potential of the farmland soil with the model approach. Results The average density of topsoil organic carbon in the study area was 2.75 kg/m² , and the spatial distribution had a moderate degree of spatial autocorrelation, showing a distribution pattern of being high at the north and south ends and low in the middle. Altitude, temperature and soil type were the main factors affecting the organic carbon density, followed by precipitation and land use method. The carbon sequestration potential of farmland topsoil was about 36.88 Tg C, equivalent to 24.10% of Chongqing's carbon emissions from energy consumption in 2018. Conclusions The soil organic carbon density was relatively high in cool and humid high–altitude areas, in Chongqing; and forests, grasslands, and paddy fields can help with the accumulation of soil organic carbon among different land use methods. Before the carbon balanceis achieved, the farmland soil, has a "carbon sink" effect as a whole, absorbing carbon from the air.

Abstract:This paper is the result of environmental geological survey engineering. Objective This study aimed to understand the stability of heavy metal pollution in farmland soils surrounding industrial zones. A total of 100 surface soil samples were collected and analyzed for the total concentration and speciation of Pb, Cr, As, Cd, and Hg as well as their association with clay minerals. Methods The extent of pollution and stability of farmland soils and health risks associated with the soil and wheat cultivated in these soils around Wuji Tannery, Xinji Tannery, Handan and Wuan Metallurgy, Guangping Chemical Plant, and Neiqiu Chemical Plant were evaluated. The evaluation was conducted using the single–factor index method, soil mineral evaluation method, and health risk assessment model. Results The analysis revealed high concentrations of Cr in Wuji Tannery soil, Hg in Neiqiu and Guangping Chemical Plant soil, and Cd and Hg in Wuan Metallurgy soil. A significant correlation was observed between heavy metals, particularly those in the residual fraction, and clay minerals such as montmorillonite, chlorite, and illite. Clay minerals exhibited high retention of Cd and Hg but low retention of Pb and As. Additionally, clay minerals in two soil samples from Wuji exceeded the Cr retention capacity Human health risk assessments indicated that soils posed a noncarcinogenic risk (1.02) to children via oral and dermal exposure. Moreover, the cancer risk index, with wheat as the intake medium, exceeded the acceptable limit (1×10^-4) for both adults (5.16×10^-4) and children (6.44×10^-4). Conclusions There is a positive relationship between heavy metals and clay minerals. Therefore, residents in industrial areas, particularly those who rely on wheat as a staple food, should pay close attention to the Cd content in wheat.

Abstract:This paper is the result of mineral exploration engineering. Objective In recent years, lithium has become a key mineral in the world's major economies, as demand has grown rapidly in the emerging and low–carbon technology industries. Especially under the "carbon peaking and carbon neutrality" goals, the demand for lithium resources is also becoming more urgent in China, but the security of lithium supply seriously restricts the development of new energy industry. At present, our lithium resources are mainly developed by the brine type and pegmatite type, but the geothermal brine type also has a certain resource potential. Therefore, it is necessary to study the distribution characteristics of lithium element in geothermal water. Methods Based on the results of investigation and study of geothermal water in China by predecessors, this paper introduces and discusses the distribution characteristics of lithium content in geothermal water, influencing factors, lithium extraction technology of geothermal water and geothermal exploration technology. Results We analyzed the lithium content of geothermal water in the main heat storage of 30 provinces and cities, and actually calculated that the annual discharge of lithium metal in the 1989 geothermal water was 789 t, and estimated that the annual discharge of lithium metal in the geothermal water was 3233 t, indicating that the geothermal water lithium resources have certain potential. Conclusions It is found that the main factors influencing the lithium content of geothermal water are the characteristics of surrounding rocks and thermal reservoir rocks, temperature, water–rock interaction, etc. It is also found that lithium isotopes have good potential in tracing the sources of geothermal systems, water–rock interactions, and material sources in continental areas. Lithium–rich geothermal water enrichment mechanism in China is mainly divided into the Himalayan geothermal belt type and Sichuan basin type, the former is related to the type in the crust remelting magma upwelling, while the latter is related to the dissolution and filtration of gypsum and halite in the strata. In addition, it is pointed out that the future prospecting direction of lithium–rich geothermal water in China will be concentrated in the Tibetan Plateau, Sichuan Basin, Jianghan Basin and oil (gas) field water. "Simultaneous exploration of geothermal water and lithium" and "simultaneous mining of geothermal water and lithium" to maximize the utilization of resources, and multiple geothermal exploration technologies will also contribute to the development of geothermal industry.

Abstract:This paper is the result of mineral exploration engineering. Objective Silver, as an important precious metal, has both industrial and financial properties and is crucial to promote national economic and social development. It is important to systematically analyze the characteristics of silver resources and demand trends for emission reduction and resource security in China. Methods From the perspective of the development of the silver industry, the characteristics of the application, geology, supply and demand and market of silver are summarized in China. According to the demand driven difference between industrial silver and non–industrial silver, the demand of silver is predicted using S–curve and ARIMA models in China from 2022 to 2035. Results Based on the resource status and demand forecast results of silver mines, the following results are obtained: (1) Silver mines have the geological characteristics of "four more and four less". It means that the total amount of resources is large and the available resources are few; more small deposits, less large deposits; more lean ore, less rich ore; more concomitant deposits, fewer independent deposits; (2) With the continuous growth of silver application field, domestic mine resources and renewable resources cannot meet the demand, so it is necessary to import silver ore and other concentrates (used to produce silver by–products, such as lead concentrates, zinc concentrates, etc.) to supplement the gap; (3) From 2022 to 2035, the demand for silver in China will continue to grow, from 5800 t to 9500 t, with an average annual growth rate of about 3.7%; (4) From 2022 to 2035, the demand for industrial silver in China will grow rapidly, from 3800 t to 7000 t, with an average annual growth rate of 4.4%. Photovoltaic systems are the main field driving the growth of industrial silver demand; (5) From 2022 to 2035, the demand for non–industrial silver in China will grow slowly, from 2000 t to 2500 t, with an average annual growth rate of 1.7%. Conclusions Based on the above research results, in order to promote the development of the silver industry chain, the following suggestions are put forward: (1) The position and role of silver in the future national economy should be paid more attention; (2) A variety of ways should be adopted to ensure the supply capacity of silver resources; (3) The added value of industrial silver products should be improved to provide guarantee for energy transformation and high–end manufacturing by increasing technological innovation and carrying out deep processing; (4) The national and private silver reserve and security system should be established to avoid large fluctuations in silver prices.

Abstract:This paper is the result of mineral exploration engineering. Objective Antimony (Sb) is one of the strategic minerals in China, thus it is imperative to construct a new antimony resource base. This study analyzes and summarizes the geological characteristics, deposit types, spatial and temporal distribution, and ore–forming sources of Sb、Sb–Au、Sb–Pb–Zn deposits in Tibet, and preliminarily summarizes the metallogenic laws of antimony deposits in Tibet, which is of great significance for guiding the new round of ore prospecting breakthroughs. Methods This paper collected and investigated the data of Sb deposits in Tibet from published literatures around the world, and combined with the latest regional geological survey results, to clarify the relationship between the mineralization of Sb deposits (prospects) in Tibet and the formation and evolution of the Tibetan Plateau from factors of geological characteristics, genetic types and geochemistry. Results The Sb deposits in Tibet are mainly of hydrothermal type. The ore bodies are mainly endowed in clastic rocks and carbonate rocks. The mantle materials have contributions to the Sb mineralization. The mineralization age is mainly from the Early Cretaceous to the Miocene (about 20 Ma). The Sb mineralization is mainly related to the collisional granitic magmatism and the post–collisional extensional magmatism. The distribution of Sb deposits in Tibet is controlled by various layered structures, faults, folds and other tectonic structures, and the ore–bearing strata are late Triassic and Jurassic–Cretaceous strata. Conclusions The Sb deposits in Tibet have the characteristics of zonal distribution, which can be divided into four major Sb metallogenic belts from west to east: western Tibet, southern Tibet, northern Tibet and eastern Tibet. The Cenozoic era is the most important metallogenic period of Sb deposits in Tibet, and the intracontinental extensional background after the strong uplift of the Tibetan Plateau is conducive to the Sb mineralization. According to the metallogenic characteristics of Sb deposits in Tibet, an applicable exploration model is proposed to provide a scientific basis for the prospecting breakthrough of Sb deposits.

Abstract:This paper is the result of mineral exploration engineering. Objective Recently, leucogranites have become a hot spot in the study of petrogenesis and rare metal metallogeny. However, the spatiotemporal distribution characteristics of global leucogranite are still unclear. For further prospecting of rare metals in China, it is essentially to clarify the spatiotemporal distribution of leucogranite and the metallogenic specialization between leucogranite and rare metal deposits. Methods We collect 1155 geochemical data from 115 leucogranites worldwide, and combine with our recently achievements from the Nanling Region, Western Sichuan, Southern Tibet, and Altai. Results In reference to the composition, this study reveals that the content of SiO₂ in leucogranite is exceed 1% higher than the global average value of granite, while the REE content of the rocks with rare metal mineralization is extremely low. Spatially, the content of SiO₂ and ALK (Na₂O+K₂O) of leucogranites in the Hercynian orogenic belt in Central and Western Europe are lower than those of the Himalayan leucogranites, as well as those of Western China. Meanwhile, the SiO₂ and ALK content of leucogranite in Western China are lower than Eastern China. Both leucogranites in Central and Western Europe and North America are rich in P₂O₅. The highest values of Li, Be, Nb, Ta, Ga, Rb and Sn in the samples appear in Central and Western Europe, while the highest values of W present in eastern China. Cenozoic SiO₂ and ALK content of leucogranite were higher than Paleozoic but lower than Mesozoic. Notablely, Paleozoic leucogranite are enriched in P₂O₅. Besides, tourmaline is a vital indicator of Neoproterozoic leucogranite. Conclusions The mineralized leucogranite are generally lack of magmatic garnet. Those leucogranite with feature of A/CNK>1.2. Rb/Sr>1, ΣREE>10×10^–6 are mostly related to Sn–W–Nb–Ta mineralization, while Rb/Sr>1, ΣREE<10×10^–6 of leucogranite more akin to Li–Sn–Nb–Ta–Be mineralization. All the data indicate that the Mesozoic leucogranites in Eastern China are the most evolved leucogranites worldwide and the best mineralization potential.

Abstract:This paper is the result of environmental geological survey engineering. Objective Nitrogen (N) is a key nutrient across Earth's terrestrial ecosystems and one of the pollution elements that cause water eutrophication. Owing to the continuous improvements of analysis and testing techniques, nitrogen stable isotope technology has developed into a common research method and analysis mean, and has been widely used in nitrogen biogeochemical cycle, water eutrophication and groundwater pollution source identification. Methods In this paper, the relevant literatures on nitrogen stable isotope in the field of ecological environment domestic and overseas in recent years were reviewed, and the research status of nitrogen isotope fractionation mechanism, nitrogen stable isotope analysis technology and nitrogen isotope applications in ecological environment were summarized, the development of remediation technologys of nitrate pollution in groundwater were briefly described. Results (1) A mature system of nitrogen isotope mass spectrometry and nitrogen isotope tracer technology has been established. (2) Nitrification and denitrification are the main mechanisms of soil nitrogen conversion cycle. Nitrogen input is realized by biological nitrogen fixation, and nitrogen output is mainly through nitrogen gas or ammoniation produced by plants or microorganisms, which is accompanied by different degrees of nitrogen isotope fractionation. (3) Nitrogen isotopes can be used to measure soil nitrogen turnover rates and N₂O emission rates, improve biological nitrogen fixation, indicate changes in atmospheric nitrogen deposition, investigate the interaction between plant and soil and determine nitrogen uptake and utilization by plants, and identify crop area sources and pollution in groundwater and atmosphere. Conclusions Future researches should focus on improving the ability of quantitative detection of uncertainty sources in the nitrogen cycle, identifying undiscovered nitrogen input, accumulation and loss pathways, and perfecting and developing ecosystem nitrogen cycle model.

Abstract:This paper is the result of ecological geological survey engineering. Objective Under the background of global climate change and the continuous expansion of human activities, natural ecosystems and their service functions are facing increasingly serious threats and recessions.In order to address this challenge, it is critical to identify and protect key sites that are of great value to ecological sustainability. Ecological security pattern refers to a comprehensive strategy and method to ensure regional ecological sustainability. Methods Based on the In–VEST model, PLUS model and circuit theory, this study evaluated the dynamic changes of ecosystem services and ecological security pattern (ESP) in the Tianshan Mountains in the arid region of Northwest China. Results The spatial distribution of land use type (LUCC) was basically stable from 1990 to 2050. In the past 30 years, the total conversion area was 32.52×10³ km², which was mainly the conversion between wasteland and grassland. Compared with 2020, the total land conversion areas under the scenarios of Natural development scenario (ND), Ecological protection scenario (EP) and Urban development scenario (UD) in 2050 are 21.43×10³ km², 23.09×10³ km² and 22.87×10³ km², respectively. Among them, the net increase of forest land area is the most, which is mainly transformed from grassland. The area of forest land, grassland and water body increased under EP scenario. In the other two scenarios, the area of construction land and cultivated land has expanded significantly. Compared with ND and UD scenarios, the ecosystem service function of EP scenario is greater. There are obvious spatial differences in ESP in the Tianshan Mountains from 1990 to 2050. The larger ecological sources and smaller resistance corridors are mainly distributed in the central and northern parts of the Tianshan Mountains with higher ecosystem service functions. On the contrary, broken ecological sources and large resistance corridors are mostly distributed in the western region blocked by sand, bare land or mountains. The southeast is a desert area, with no ecological source and lack of ecological corridors. In the past 30 years, the area of ecological source area has decreased by 1.84×10³ km², showing a trend of fragmentation, and the ecological network is more complex. Compared with 2020, the area of ecological source and pinch point under EP scenario in 2050 will increase by 10.53×10³ km² and 0.11×10³ km² respectively, and the area of ecological barrier zone will decrease by 0.38×10³ km². In addition to the EP scenario, the ecological source area of the other two scenarios also increased, but lower than the EP scenario. Conclusions Ecological protection scenarios play a vital role in shaping LUCC and are of great significance for maintaining ecological security and ecosystem integrity.

Abstract:This paper is the result of agricultural geological survey engineering. Objective Soil quality is closely related to human activities. Given that traditional methods fall short in achieving the large–scale dynamic monitoring of soil quality, the quantitative inversion of elements in soils using hyperspectral remote sensing, which proves macroscopic, real–time, in–situ, and fast, has emerged as a hot topic and challenge in the field of remote sensing application. Methods This paper explores three methods for quantitative remote sensing inversion of elements in soils: direct quantitative inversion, indirect quantitative inversion using correlations among the elements, and quantitative inversion based on plant spectra. Specifically, this paper systematically summarizes the primary principles, advantages, and current research status of these methods and proposes future trends in relevant fields from the perspective of interdisciplinary integration. Results The commonly used methods for the quantitative inversion of elements in soils face challenges when applied on a large scale. Among these, the indirect inversion based on the spectra of plant leaves or canopies is considered the most reliable. Achievements in ecological geochemistry enable the identification of the unique spectral effects of target elements in different plants, which assists in determining the principle of the plant spectrum–based quantitative inversion of elements in soils. Conclusions More in–depth research based on big data mining and the physicochemical properties of soils while promoting interdisciplinary integration represents a favorable direction for achieving breakthroughs in wide–area monitoring technology for elements in soils.

Abstract:This paper is the result of soil environmental survey engineering. Objective The objective is to identify the impact of characteristic pollutants (Cr (III), salt, organic matter) in the leachate of tannery sludge on the conversion of soil NH₄⁺–N conversion and microbial community structure. It provides a theoretical basis for the safe agricultural use of tannery sludge and soil pollution prevention and control. Methods The transformation of NH₄⁺–N to NO₃^––N in soil was studied through soil cultivation experiments under different pollution conditions, and the high–throughput sequencing is used to analyze the composition and structure characteristics of microbial community in soil. Results The characteristic pollution components in the tannery sludge leachate inhibit the nitrification process of NH₄⁺–N in the soil, and the influence factors are sorted as follows: Cr(III)>saltness>organic matter. The exogenous Cr(III) pollution has a significant inhibitory effect on the transformation rate and amount of NH₄⁺–N, whereas the saltness and organic matter only delay the start time of nitrification and reduce the nitrification rate in soil. With the increase of Cr(III) content from 100 mg/kg to 250 mg/kg, the transformation amount of NH₄⁺–N decreases from 94.23% to 19.38% after 90 days of culture. The high Cr(III) and salinity in the leachate have a significant impact on the microbial community structure and distribution in the soil at the initial stage of pollution. With the decrease of the bioavailability of Cr(III) and the enhancement of microbial adaptation in soil aging process, the microbial community structure and composition in Cr(III), salinity, and organic matter contaminated soils become similar, and the abundances of nitrifying bacteria (Nitrosospira, Nitrosomonas and Nitrosospira) also have an obvious increase. Conclusions The results of RDA analysis show that the main characteristic factors affecting the evolution of microbial community structure in tanning contaminated soil are: Cr(III) (R²=0.53, P<0.01), NH₄⁺–N (R²=0.59, P<0.005) and NO₃^––N(R²=0.53, P<0.01).

Abstract:This paper is the result of environmental geological survey engineering. Objective This study aims to evaluate the current status of heavy metal contamination in the soil of Dashetai, Ulat Front Banner. A comprehensive sampling campaign was conducted, involving the systematic collection of 845 topsoil samples, 30 crop samples, and 17 drinking water samples. The concentrations of eight heavy metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pb), and Zinc (Zn)) were analyzed to assess the extent of contamination. Methods The levels of soil heavy metal contamination, ecological risk, and associated health risks in the study area were assessed using the geoaccumulation index method, the potential ecological hazard index method, and a health risk assessment model. Results The concentrations of heavy metals in the farmland soils of Dashetai are approximately equivalent to the background levels observed in the Hetao Plain. The assessment of potential ecological risks indicated that the heavy metal contamination in the soil predominantly posed slight to moderate ecological hazards. The human health risk assessment revealed that, through oral and dermal exposure, the soil's carcinogenic risk value was calculated to be 5.69 × 10^–6, which exceeds the standard threshold of 10^–6. However, this level of risk is considered to pose a minimal carcinogenic threat, one that is generally deemed acceptable by public health standards. Conclusions The distribution of mercury (Hg) is significantly influenced by anthropogenic activities, with areas of medium to high risk predominantly located in Dashetai. In contrast, the distribution of other elements is primarily governed by the parent materials of the soil. Moderate–risk areas for cadmium (Cd) are concentrated along the coast of Wuliangsu Lake. Arsenic (As) was identified as the primary contributor to the health risks associated with the consumption of vegetables, grains, and drinking water.

Abstract:This paper is the result of hydrogeological survey engineering. Objective In order to determine the sources and control factors of main ions and dissolved inorganic carbon (DIC) in water of the Huixian karst wetland, Methods groundwater and surface water samples were collected from the Huixian karst wetland to analyze the hydrochemical ions and dissolved inorganic carbon isotope(δ¹³C_DIC). Results The Ca–HCO₃ water was identified as a main hydrochemical type in most water samples of the Huixian karst wetland. The dissolution of carbonate rock was primary contributor to Ca²⁺, Mg²⁺ and HCO₃^–, while NO₃^– was mainly derived from synthetic fertilizers and soil organic nitrogen. Moreover, K⁺, Na⁺, and Cl^– were driven by the mixed inputs of synthetic fertilizer, manure, and sewage, and the acid rain and pyrite oxidation contributed more to karst water SO₄^2–. Further, karst water DIC was respectively derived from the soil CO₂ with the contribution rate of 46% and from the carbonate minerals with the contribution rate of 54% according to the obtained result from isotopic mass balance. In addition to the H₂CO₃ produced from CO₂ and H₂O, the H₂SO₄ derived from sulfur–containing minerals, acid rain, and anthropogenic emissions was involved in carbonate weathering in the Huixian karst wetland. Additionally, microbial nitrification processes of the reduced nitrogen fertilizers could be also ignored in the study area. For the surface water, the DIC was mainly derived from groundwater recharges, and the value of δ¹³C_DIC was affected by the photosynthesis of aquatic plants and CO₂ degassing, thereby resulting in the more enrichment of δ¹³C_DIC compared with that in groundwater. Conclusions The obtained results provided insights into the understanding of minerals weathering and biogeochemical processes, and also highlighted the control factors of hydrogeological conditions and human activities in precisely determining hydrochemical mechanisms in the karst wetland.

Abstract:This paper is the result of geological survey engineering. Objective The sedimentary period of the Qiaotou Formation in Liaoning is still not accurately determined, which leads to controversial discussions about its depositional background, especially the palaeoclimate. It is of great significance to discuss its depositional background by using petrogeochemical characteristics and other methods. Methods We reconstructed the palaeo–weathering climate conditions, palaeo–salinity and palaeo–oxidation–reduction conditions by analysing the elemental ratios of CaO/(CaO+Fe), Sr/Ba, and V/(Ni+V), as well as the parameters of CIA, ICV, and Ce_anom from the petrogeochemical data of the sandstones of the Qiaotou Formation. Results Most of the CIA values of the sandstone samples from the Qiaotou Formation are located in the warm and humid region, while most of the ICV values are located in the cold and dry region. Most of the CaO/(CaO+Fe) and Sr/Ba values of the samples fall into the medium saline region, and a small amount is in the slightly saline region. V/(Ni+V) and Ce_anom values of sandstone samples are in the reduced region, and a small amount is in the oxidised region. Conclusions The Qiaotou Formation was not deposited in the Nanhua Period, and its depositional period was generally in an anoxic reducing environment with medium saline water and a warm and humid climate.

Abstract:This paper is the result of geological survey engineering. Objective Microbially induced sedimentary structures (MISS), one of the international research hotspots, have been paid more attentions in Precambrian rather than other period in China. Microbials flourished globally in the Early Ordovician. However, the MISS was found in the shallow water clastic rocks in France and Newfoundland of Canada, but not yet reported in China. Methods Here, we first discovered the MISS at the upper Nantsinkuan Formation of Early Tremadocian of Early Ordovician in Jieling area, Yichang, Hubei Province. Results The MISS at Jieling contained microbial mat growth features and microbial mat destruction features. It is noteworthy that the microbial mat destruction features are morphologically similar to the molar tooth that widely developed in Precambrian. Conclusions The discovery of the MISS in Jieling not only enriches the global MISS–bearing stratigraphic units, but also has important theoretical significance for the study of Phanerozoic microbialites. Moreover, it is an important supplement to the geological relics of Yichang City.

Abstract:This paper is the result of geological survey engineering. Objective To better understand the Paleo–Mesoproterozoic tectonic evolution of the Dabie orogen in the northern margin of Yangtze Block, we demonstrated the geological and geochronological characteristics for sedimentary rocks in the Lüwang–Gaoqiao mélange. Methods Geological mapping for the mélange was conducted. LA–ICP–MS zircon U–Pb isotopic analyses were carried out on the graphite–bearing quartzite. Results The graphite–bearing sedimentary rocks in Lüwang–Gaoqiao mélange are dominated by sandstones with high maturity, siliceous argillaceous rock, and carbonaceous. U–Pb dating reveals that the graphite–bearing quartzite has original deposition age of ~1.43 Ga, displaying detrital zircon age peaks at 2.55 Ga, 2.06 Ga, 1.86 Ga and 1.43 Ga. The sedimentary materials mainly came from the basement of the Yangtze Block. Conclusions The Mesoproterozoic clastic sedimentary rocks and carbonates from the Lüwang–Gaoqiao mélange were formed in a continental margin setting. They recorded an extensional regime for the Dabie orogen in the northern margin of Yangtze Block, during the break–up of the Columbia supercontinent.

Abstract:This paper is the result of oil and gas exploration engineering. Objective The structural uplift of Chaoshan depression is controlled by the development degree of sandstone reservoir and tectonic conditions. It’s flank depression provides a source of hydrocarbon, which is the most favorable area for zones of hydrocarbon accumulation. The Mesozoic sandstone reservoirs in the Chaoshan Depression have obvious low–density characteristics based on the elastic parameters of seismic inversion to predict the oil and gas properties, while the density of other lithologies is high. Methods The elastic parameters such as density and Poisson's ratio were directly inverted from the pre–stack seismic data, and the development of sandstone reservoirs and the distribution of hydrocarbons were predicted through the density inversion results, so as to realize the prediction of the Mesozoic oil and gas content. Results The Poisson's ratio is sensitive to hydrocarbons, and the reservoir has obvious characteristics of low Poisson's ratio after hydrocarbons. Conclusions The elastic parameters of seismic inversion are used to predict the oil and gas properties, and the hydrocarbon anomalies are obvious, and the predicted structural uplift has good oil and gas properties. The pre–stack elastic parameter inversion technology greatly reduces the multi–solution and uncertainty of reservoir prediction in well–free areas, and improves the accuracy and reliability of inversion results.

Abstract:This paper is the result of environmental geological survey engineering. Objective The cascade of disasters caused by landslide–dammed lakes is highly destructive, with its formation and outburst processes significantly influenced by the external environment. The sediment within the dammed–lake serves as a valuable tool for documenting the entire lifecycle of thedammed–lake, offering important insights into paleoenvironment and paleoclimate. Utilizing the most effective analytical methods to interpret this sediment can aid in reconstructing the sediment deposition process and understanding changes in paleoenvironment. Methods Through sediment sampling for field investigation and laboratory analysis, the suitability of statistical characteristics of dammed lake sediments is assessed using graphical and moment methods. The sediment environment of the dammed lake is reconstructed by analyzing particle size in conjunction with organic matter content, allowing for the restoration of the development process of the dammed lake. Results (1) The stratified sediment sequence of the dammed lake sediment is distinct, representing a monogenic hydrodynamic lacustrine sediment with consistent material sources rather than polygenic sediment. Analysis of the organic matter and sediment grain size variations indicates that the dammed lake has undergone four cycles of wet–dry periods, with at least three instances of blockage–overflow deposition processes resulting from the combination of climatic and geological factors. The estimated sedimentary cycle period is approximately 1750 a. It is suggested that the sedimentation history is a consequence of prolonged and intricate activities within the fault zone, as well as the combined influence of climate and river dynamics. (2) The statistical analysis results from the graphical method and the moment method indicate a high level of agreement in assessing the average grain size and sorting coefficient, suggesting that they are interchangeable. However, the partial kurtosis values obtained from the moment method are greater than those from the graphical method, necessitating a linear adjustment for practical application. Additionally, deviations from statistical expressions are observed in the skewness and kurtosis due to the reference value description. Conclusions The grain size distribution of the sediment from the dammed lake is straightforward and easily calculated, making it convenient for comparison with other sediment types. The graphical method is suggested for these calculations. The findings indicate that the grain size characteristics offer valuable insights into understanding the deposition and outburst processes of dammed lake, as well as the response of landslide disasters to climate change. This information can serve as a theoretical foundation for reconstructing the paleoenvironment and paleoclimate of the dammed lake during its deposition phase.

Abstract:This paper is the result of hydrogeological survey engineering. Objective Due to the limitation of terrain conditions, the ecological environment of plateau valley cities is fragile, and the strong human activities have had a severe impact on groundwater. Iron and manganese ions have become the main contribution index of super–class III groundwater in shallow groundwater in Xining, a typical plateau valley city, which seriously threatens the local ecological environment security .and the health of residents. The distribution characteristics and influencing factors of iron and manganese in shallow groundwater in plateau valley cities are deeply explored in order to provide technical support for the prevention and control measures of groundwater pollution and the alleviation of water quality safety problems in this area. Methods Based on the test results of hydrochemical composition of 144 groups of shallow groundwater samples in Xining city, combined with the geology, landform, land use type, hydrogeological investigation data and the influence of human activities, this paper studies the distribution characteristics and influencing factors of Fe and Mn in shallow groundwater in Xining city. Results The over–standard rates of Fe and Mn in shallow groundwater in the study area are 20.98% and 9.79%. Compared with 2012, the contribution rate of Fe and Mn ions to Class Ⅲ groundwater increased by 2 and 3, respectively. The excess rate of Fe and Mn in shallow groundwater of construction land is 1.4 times and 3.47 times higher than that of other land use types, respectively. There are 36 hydrochemical types of shallow groundwater in the study area, and 21 hydrochemical types of groundwater in construction land. Groundwater with high Fe and Mn is mainly enriched in HCO₃–Ca·Mg type water and HCO₃·SO₄–Ca type water. The migration and enrichment of Fe and Mn ions in groundwater are mainly controlled by oxidation–reduction environment, and have no obvious correlation with acid–base conditions, except for the properties of overburden, ground pollution, groundwater runoff conditions. Conclusions The increase of Fe and Mn content in groundwater in the study area is mainly caused by the primary sedimentary environment, while the increase of Fe and Mn content in shallow groundwater in local construction land is caused by the primary sedimentary environment and human activities. Therefore, it is necessary to monitor the Fe and Mn content in groundwater in construction land for a long time and formulate corresponding management measures to prevent the increase of Fe and Mn content in shallow groundwater in the future.

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