Abstract:This paper is the result of geological environment survey engineering.[Objective]Phytoremediation technology has been widely used in mine ecological restoration because of its characteristics of green, economic and environmental protection. The investigation and screening of plant species adapted to local habitats around mines is the key link of plant ecological restoration.[Methods]By the method of soil sampling for investigation and laboratory analysis, this work analyzed 11 dominant plants in the abandoned tailing and the surrounding of Baotou, Inner Mongolia. Test the contents of heavy metals, the enrichment and translocation of heavy metals and the contents of heavy metals of the plant root soil, in order to screen fine restoration plants and provide scientific basis for ecological restoration in mining area.[Results]The results showed that the mean contents of Fe, Mn, Cu, Pb, Zn, Cr, Cd, F much higher than the background value of soil in Hetao Plain, geoaccumulation index revealed the pollution level is 2-7, levels of pollution range from mild to moderate pollution to extremely intense pollution. Heavy metal content in plants shows that the content of each element in the underground part of plants is generally higher than that in the aboveground part, the content of heavy metals in most plants exceeded the normal range except for Cu.[Conclusions] Artemisia desertorum and Lepidium apetalum are belong to accumulators, Zea mays, Setaria viridis, Chloris virgata and Calamagrostis epigeios which absorbed a large amount of heavy metals but mainly held in the roots, Suaeda glauca, Chenopodium album, Xanthium sibiricum, Populus alba and Salix microstachya are belong to excluder. According to the absorption and enrichment characteristics of heavy metals in plants, aim to provide reference for the establishment of artificial phytoremediation system in mining areas and the selection of appropriate plant species for the remediation of heavy metal polluted soil in mining areas.
Highlights: The heavy metal characteristics of 11 dominant plants in the abandoned iron tailings pond and its surrounding areas were studied. The mechanism of heavy metal uptake by dominant plants was revealed.

Abstract:This paper is the result of agricultural geochemical survey engineering.[Objective] As a heavy metal, cadmium (Cd) mainly enters the food chain through the "soil=plant" system and affects human health. It is great significant to study the accumulation of cadmium in crops to ensure human health and safety.[Methods] Soil and rice samples from Nanchong, Bazhong and Guang'an in the northeast Sichuan were collected. The cadmium content in soil and rice was analyzed by ICP=MS, and the data were statistically analyzed by CART decision tree and correlation coefficient methods.[Results] The research shows that the cadmium content of the soil in the northeast Sichuan is relatively low, ranging from the safety threshold. In contrast, the cadmium content of the rice (brown rice) varies from 0.002 to 0.803 mg/kg and with an average value of 0.076 mg/kg, 14.0% of which is above the safety threshold. The daily cadmium intake of adults reaches 90.4 μg/d in the region with excessive cadmium in rice, exceeding the permissible cadmium intake of 60 μg/d.[Conclusions] The phenomenon that cadmium content does not exceed the safety threshold in soil but it does in rice may be related to the characteristics of low pH, low CaO and high SiO₂ of the soil. This recognition is great significance for guiding grain production in this region. 0.071 to 0.92 mg/kg and with an average value of 0.254 mg/kg. The cadmium content of almost all (99.9%) soil samples is below
Highlights: By the comprehensive survey of soil and rice, it was found that cadmium content does not exceed the safety threshold in soil but it does in crop, and the CART and correlation coefficient methods were used to analyze the reasons.

Abstract:This paper is the result of hydrogeological survey engineering.[Object]Reveal the characteristics and interaction of D and ¹⁸O between surface water and groundwater in the northern new town of Wuhan,[Methods]7 precipitation samples, 6 river samples, 14 reservoir samples, 98 minjing samples, 3 spring samples and 11 borehole samples were collected and measured in 2019, what' s more, 50 monitoring data of Wuhan station from 1986 to 1998 were collected. The research methods of D and ¹⁸O spatial analysis and watershed analysis are carried out in this paper.[Results](1) The D and ¹⁸O isotopes of precipitation in Wuhan vary with seasons, and the negative correlation between isotopic value and precipitation indicates "rainfall effect", but the no correlation between isotopic value and temperature indicates "no temperature effect". (2) Due to strong evapotransporation, the surface water shows the certain correlation between isotopic value and geomorphic types, and the main stream is enriched in stable isotopic, while the tributaries is depleted; (3) Groundwater such as wells, springs and boreholes are all derived from atmospheric precipitation, and the stable isotopes value of groundwater is related to the buried depth and geomorphic type; (4) During the dry season, the Jiehe River is recharged by upstream reservoir and underground water in the Jiehe basin, and the XiaJiasi reservoir is recharged by underground water in the XiaJiasi reservoir basin.[Conclusion]D and ¹⁸O can significantly improve the understanding of the conversion relationship between surface water and groundwater in the northern new town of Wuhan.
Highlights: Based on the D and 18O composition and spatial distribution characteristics, the mutual transformation law of precipitation, surface water and groundwater in the northern new town of Wuhan is revealed.

Abstract:This paper is the result of geological survey engineering.[Objective]The Taiyuan Basin is one of the areas where its distribution of beneficial Karst geothermal reservoir and demand of urban heating are well matched. The research on the evolution of Karst geothermal system and the characteristics of genetic elements in Taiyuan Basin has a great significance for the overall development of geothermal resources in this area and the understanding of the distribution of geothermal resources in rift basins.[Methods]Based on the previous research and the latest data of 54 geothermal wells, we analyze the heat source, geothermal reservoir distribution and hydrothermal dynamic characteristics of karst geothermal system in Taiyuan Basin, and also evaluate the geothermal resources by 8 effective structural units.[Results]The results show as flow:(1) The strata of karst thermal reservoir in Taiyuan Basin are mainly developed in the Lower Paleozoic Ordovician,, which is widely distributed in North China Plate. And the evolution of the karst geothermal reservoir has gone through five stages, i.e. the epigenic karstification at the end of the Early Paleozoic, the direct caprock deposition in the Late Paleozoic, the initial formation of the karst geothermal system during Mesozoic, the transformation during the Neogene and the final setting during the Quaternary. (2)The heat source of the geothermal system comes from the high terrestrial heat flow (up to 79.12mW/m2) generated by the Cenozoic rift basin, and the heat transfer mode can be divided into two different types:the strong convection type at the edge of the basin and the heat conduction type inside the basin. (3) The geothermal reservoir property is in the longitudinal and horizontal zonation. In the vertical direction,15-20 effective reservoir sections are identified, with a accumulated thickness of 160~180m, which can be divided into 3-4 layers of main water-bearing section; on the plane, the favorable reservoir belt is mainly controlled by NE trending concealed structure, and the main water-bearing layer is easy to generate a "over-flow" phenomenon during the migration process. The Ordovician reservoir in the middle of the basin with moderately buried (about 400~1900 m) and high temperature (30-75℃) charcteristics is the most favorable exploration and development area. (4) According to the geothermal reservoir volume method, the total geothermal resources of the karst geothermal system in Taiyuan Basin are estimated to be 8.303 billion GJ, which is equivalent to 283 million tons of standard coal.[Conclusions]The annual exploitation of geothermal resources can meet the heating area of 15.02 million square meters. At present, the developed resources only account for 23.3% of the exploitable resources, the development potential is huge.
Highlights: The genetic model of the karst geothermal system in the inter- mountain rifted basin is studied according to the controlling effect of regional tectonic- sedimentary cycle on the components of the geothermal system; The longitudinal stratification and plane separation of thermal reservoir properties are analyzed, based on the water production of geothermal wells and the interpretation results of logging curves; The geothermal resources of the karst geothermal system in the Taiyuan Basin were finely evaluated by using the thermal reservoir volume method.

Abstract:This paper is the result of geological hazard survey engineering.[Objective]Debris flow is a major geological disaster widely distributed in Bailong River Basin and often causes mass casualties. Accurate evaluation of the scale and risk of debris flow is the premise of the early warning and prediction of debris flow. Reasonable construction of risk prediction model is the key to debris flow disaster prevention and reduction.[Method] Based on the reported debris flow cases and corresponding rainfall data in the study area, the quantitative evaluation model of potential debris flow risk in Bailong River Basin is constructed by analyzing the key geological environmental conditions and their relationship, and two kinds of critical discrimination models of debris flow risk level are proposed.[Results]The results show that:(1) The dynamic quantitative calculation model of debris flow risk degree with debris flow activity scale, average gradient of gully bed, watershed cutting density and unstable gully bed ratio can be used as judgment factors to quickly and accurately predict the risk degree of debris flow under different engineering scenarios and rainfall frequencies in the future; (2) The topographic conditions affecting the occurrence of rainfall type debris flow are composed of watershed area, slope area ratio of 10 °-40 °, average longitudinal ratio of gully bed, etc; the rainfall conditions are mainly composed of 24 h cumulative rainfall before the outbreak of debris flow, 1 h rainfall or 10min rainfall triggering debris flow, etc; (3) Based on the risk calculation results of 30 typical debris flow gullies, the critical discrimination value of debris flow risk is obtained, and the 1h prediction model and 10min prediction model of potential debris flow risk of rainfall type are proposed. Among them, the prediction accuracy of debris flow above high risk of class I model is greater than 87.5%, the prediction accuracy of debris flow above medium risk of class II model is greater than 80%, and the verification accuracy of the two prediction models is 83.3%.[Conclusions]The research results provide technical support for the accurate early warning and prediction of debris flow, and have a certain reference significance for the establishment of small and medium-sized debris flow real-time early warning system.
Highlights: By determining the key geological environmental factors corresponding to debris flow, a dynamic quantitative evaluation model of debris flow risk is constructed. According to the critical discrimination model of debris flow risk for 1h and 10min, the early warning and prediction of potential debris flow can be realized accurately.

Abstract:This paper is the result of marine hydrates exploration engineering.[Objective] The China Geological Survey successfully carried out two NGH production tests in the Shenhu area in the northern South China Sea (SCS) in 2017 and 2020, setting multiple world records, such as the longest gas production time, the highest total gas production, and the highest average daily gas production. Understanding and mastering the phase transition and seepage mechanism of natural gas hydrate reservoir exploitation in the SCS will help to further reveal the decomposition mechanism, production law, and production increase mechanism of this type of hydrate, and provide a theoretical basis for large- scale and efficient exploitation of hydrate resources in China sea.[Methods] As suggested by the in-depth research on the two production tests, key factors that restrict the gas production efficiency of hydrate dissociation include reservoir structure characterization, hydrate phase transition, multiphase seepage and permeability enhancement, and the simulation and regulation of production capacity, among which the hydrate phase transition and seepage mechanism are crucial.[Results] Study results reveal that the hydrate phase transition in the SCS is characterized by low dissociation temperature, is prone to produce secondary hydrates in the reservoirs, and is a complex process under the combined effects of the seepage, stress, temperature, and chemical fields. The multiphase seepage is controlled by multiple factors such as the physical properties of unconsolidated reservoirs, the hydrate phase transition, and exploitation methods and is characterized by strong methane adsorption, abrupt changes in absolute permeability, and the weak flow capacity of gas. To ensure the long-term, stable, and efficient NGHs exploitation in the SCS, it is necessary to further enhance the reservoir seepage capacity and increase gas production through secondary reservoir stimulation based on initial reservoir stimulation.[Conclusions] With the constant progress in the NGHs industrialization, great efforts should be made to tackle the difficulties, such as determining the micro-change in temperature and pressure, the response mechanisms of material-energy exchange, the methods for efficient NGH dissociation, and the boundary conditions for the formation of secondary hydrates in the large-scale, long-term gas production.
Highlights: The hydrate phase transition in the SCS is a complex process under the combined effects of the seepage, stress, temperature, and chemical fields; The clayey silt reservoir in the SCS is characterized by strong methane adsorption, abrupt changes in absolute permeability, the weak flow capacity of gas, etc., and the multiphase seepage mechanism is complex.

Abstract:This paper is the result of environmental geological survey engineering.[Objective]In recent years, ecological and environmental pollution caused by microplastics has attracted widespread interest.[Methods]This paper reviews recent progress in research on the sources and hazards of microplastics and detection and treatment technologies investigated in a large number of studies.[Results](1) The primary sources of microplastics in soil are the cracking of agricultural land film without efficient recycling, use of sewage sludge containing microplastics in agricultural production activities, and settling of microplastics from air to surfaces; (2) Microplastics in soil can adsorb heavy metals, antibiotics, and other pollutants, which can change the pH, bulk density, and physical and chemical properties of soil, affect the development of earthworms and other soil animals, and reduce the activities of crucial microorganisms involved in the soil nutrient cycle, thereby harming the soil environment; (3) No unified technical standard for microplastic separation and detection is currently available. Visual inspection and spectroscopic and thermal analysis techniques are the main methods for detecting microplastics.[Conclusions] Microplastics in soil prese nt varied levels of risk to the environment and health of animals and plants and threaten human health through the food chain. Future research can focus on blocking the sources of soil microplastics, the pollution mechanism of soil microplastics and heavy metal compound pollution, and innovations in soil microplastic detection technologies.
Highlights: (1) Research on soil microplastics is at its initial stage. This paper summarizes the impact of soil microplastics on crops and soil environment and the risk of their spreading to the food chain, providing useful reference for future research on environmental pollution and human health. (2) This paper elucidates the sources of soil microplastics on the basis of agricultural production activities. Owing to challenges in the remediation of soil polluted by microplastics, authors propose strategies for blocking the sources of microplastics in soil, with the primary aim of effectively reducing microplastic inputs in soil.

Abstract:This paper is the result of agricultural geological survey engineering.[Objective] Natural selenium (Se)-enriched agricultural products is the safest and most effective way for human Se uptake. The Serich agriculture and Se- rich characteristic towns, which should be established based on natural Se- rich land, have become the pillars of emerging industries for poverty alleviation and rural revitalization. Their planning and construction should be based on the quality evaluation of Se-rich land, but there is a lack of the method for this evaluation.[Methods] Taking Xintian County as an example, a new system of Se-rich arable land quality evaluation was established, which was composed of the evaluation of land fertility, economic quality, and ecological environment. The evaluation system was based on the development potential, utilization value, and restriction conditions of the arable land. Additionally, this paper carried out a comprehensive evaluation of the natural, environmental, and economic attributes, based on the results of Comprehensive Survey of Se- enriched Soil Geochemistry and National Land Survey in Xinxu Town of Xintian County.[Results] The evaluation results are coincident with the quality of agricultural products and Se- rich degree, which reflected the development conditions and the potential of arable land resources.[Conclusions] The above- mentioned evaluation system can guide the development and utilization of Se- rich arable land, and can be used for the planning of Se-rich land resources and related industry.
Highlights: Based on the development and utilization conditions and potential, development and utilization value, and restriction conditions, the quality evaluation system of Se-rich arable land was constructed, which was composed of land fertility, economic quality, and ecological environment. The methods and rules of index weight, investigation and evaluation unit, single factor grade, and comprehensive classification were formulated.

Abstract:This paper is the result of hydrogeological and environmental geological survey engineering.[Objective] Terrestrial hydrothermal spring travertine, as a common terrestrial carbonate sediment/rock in volcanic and geothermal areas, is widely used to restore paleoenvironment, but the proxy indicators that can reflect paleoclimate information are mostly controlled by complex external conditions. The extraction of paleoclimate information from hot spring travertine requires further research.[Methods] This paper summarizes the current successful cases of hydrothermal travertine in reconstructing paleoclimate information, and sorts out various climatic and non- climatic influencing factors related to the deposition of hydrothermal travertine.[Results] The authors believe that C- O isotopes, major and trace elements are more feasible for the selection of palaeoclimate restoration proxies for hydrothermal travertine. The palynological data can be used as corroborative information due to the limitation of sporopollen preservation, and can be used in conjunction with other climate proxies. indicators to test whether the palaeoclimate significance is correct or not. At the same time, it is necessary to compare various climatic proxies in thermal spring travertine with relatively mature paleoclimate research methods such as biostratigraphy, ice cores, stalagmites, etc., so that various paleoclimate proxies can be verified with each other, so as to better obtain the information on the medieval climate of the hot spring travertine.[Conclusion] It is feasible to extract and restore reliable paleoclimate information by using various climatic proxies in hot spring travertine.
Highlights: This paper reviews the successful cases of hydrothermal travertine restoration of paleoclimate at home and abroad, and deeply discusses the problems existing in the study of paleoclimate restoration for hydrothermal travertine.

Abstract:This paper is the result of hydrogeological survey engineering.[Objective] The purpose of this study is to uncover the spatial-temporal distribution, genesis, and environmental impacts of shallow acidic groundwater in the Fangchenggang area.[Methods] In-situ pH values of shallow groundwater were determined in the study area during 2013 to 2015, including 214 samples in the dry season and 168 samples in the wet season. Spatial and temporal distribution, genesis, and ecological influences of the pH values were discussed.[Results] Results show that the acidic groundwater samples (pH < 6.5) account for 79.3% and 64.3%, respectively, in the wet and dry seasons. In general, pH values in the wet season are lower than in the dry season. Values are generally lower in the low mountain areas (pH 5.0-5.5, mean 5.18, n=4) relative to the hillys (pH mostly 5.0- 6.5, mean 5.97, n=202), and the plain areas (pH typically 6.5- 8.5, mean 6.77, n=8).[Conclusions] Occurrence of acidic shallow groundwater can be contributed primarily to the acid rain, and partly to the acidic unsaturated zone, and oxidation of sulfide minerals. Accordingly, seasonal changes of acidic rain should principally responsible for the spatial variations of groundwater pHs. By contrast, however, tides could increase groundwater pH values in the Jiangping area. Acidic groundwater threatens safe drinking water supply, because only 20.6% samples in the dry season having pHs within the drinking water standard thresholds. Also, it may promote release of some harmful elements from aquifer sediments, and erode underground pipe networks and building pile foundations. In addition, due to discharge, acidic groundwater could influence surface water environment and surface ecosystems. This study contributes to water resources management in the study area.
Highlights: Base on the advantages of geological survey data, this study uncovers the spatial- temporal distribution of acidic shallow groundwater in the Fangchenggang area. In general, occurrence of acidic shallow groundwater can be contributed to the acid rain, acidic unsaturated zone, and oxidation of sulfide minerals. Finally, the possible impacts of acidic groundwater on the ecological environment were identified.

Abstract:This paper is the result of hydrogeological and environ mental survey engineering.[Objective] In order to find out the characteristics and evolution of groundwater in Changchun new area and support the construction of northeast old industrial base.[Methods]Based on the investigation and sampling, this paper makes full use of the previous achievements and data, and applies SPSS analysis software and groundwater pollution analysis software, through the analysis of the geological conditions, the spatial distribution characteristics of hydrochemical parameters, the chemical types of groundwater and the chemical causes of groundwater in Changchun new area, a series of results are obtained.[Results]The groundwater in Changchun new area has high hardness and mineralization, HCO₃^－ is dominant in the ions of groundwater, and the absolute mass concentration of Ca²⁺、Cl^-、O₄^2-、Na⁺ is relatively high; the mass concentration of pH,H₂SiO₃、Sr,TDS,Mg₂₊,HCO₃ is relatively stable; the ions of groundwater are mainly HCO₃^－ and Ca²⁺; Na⁺ and K+ are from the dissolution of rock salt and siliceous rock; Ca²⁺ and Mg²⁺ are mainly from carbonate dissolution of salt.The quality of groundwater in the area can be divided into four grades, among which class V water is not evaluated.[Conclusions] In general, class I water accounts for 7.50%, class II water 32.10%, class III water 20.80%, class IV water 39.60%. More than 60.4% of the groundwater is in good condition.
Highlights: The chemistry, origin and evolution of groundwater in national new areas are studied, and the water quality characteristics of groundwater are obtained, which can effectively support the healthy development of regional ecology.

Abstract:This paper is the result of hydrogeological survey engineering.[Objective]In recent years, the drinking water health issues has been taken due to the improvement of living standards. Finding and developing high- quality groundwater with high- level minerals (e.g. H₂SiO₃) has become the key step in improving human health.[Methods]The hydrogeological survey and groundwater pollution survey were carried out in the Zhaojue County, and the spatial distributions of H₂SiO₃-rich groundwater, hydrogeochemical components characteristics and factors were revealed.[Results] The main results including:(1)The groundwater with H₂SiO₃ (≥ 25mg/L) was identified as the low salinity and alkaline water, which distributed in the six areas with the basement rocks of basalt. The H₂SiO₃ concentration was generally 25.74-46.04 mg/L, pH level was generally 7.4- 8.58, and TDS level is generally 49.4- 333 mg/L;(2)The H₂SiO₃- rich groundwater of study area was characterized by the low mineralization while the main hydrochemical types of groundwater are HCO₃- Ca·Mg and HCO₃- Ca;(3) The H₂SiO₃- rich groundwater was influenced by the water- rock interactions, the distribution range and solubility of silicate minerals, the development of surrounding rock fissures, and water conservation and recharge conditions in the county, among which the water- rock interactions play a critical role; (4) It is necessary to further reveal the main factors affecting the distribution and migration of H₂SiO₃ in groundwater in the subsequent development and utilization process.[Conclusions]The results can provide a basis for the development of mineral water industry and the construction of urban and rural high-quality water sources in Zhaojue area.
Highlights: The spatial distribution characteristics and hydrochemical characteristics of high-quality metasilicate groundwater were systematically summarized in Zhaojue County; The formation mechanism of high-quality metasilicate groundwater was discussed from the perspective of formation conditions and water-rock interaction.

Abstract:This paper is the result of agricultural geochemical survey engineering.[Objective]The research aimed to provide a scientific basis for the rational use of soil nutrients in agricultural production, adjustment of agricultural structure and improvement of land use value in Renhuai.[Methods]Total and available nitrogen (phosphorus and potassium) content and organic matter content of 5,486 topsoil samples were obtained using inductively coupled plasma emission spectrometry, volumetric method, and potentiometric method. Their geochemical characteristics and influencing factors were systematically studied.[Results]The average values of nitrogen, phosphorus, potassium, organic matter, available nitrogen, rapidly available phosphorus, and rapidly available potassium were 1.74 g/kg, 0.75 g/kg, 19.90 g/kg, 30.90 g/kg, 100.28 mg/kg, 10.40 mg/kg, and 101.03 mg/kg, respectively. The contents and distributions of nitrogen, available nitrogen, phosphorus, potassium, and organic matter were closely related to the stratum, whereas those of rapidly available phosphorus and rapidly available potassium were not. Cultivated land in Renhuai had a relatively high soil fertility rating, which was mainly dominated by relatively rich soil grades, with the share of relatively rich and rich grades reaching 57.6%. Rich nitrogen, phosphorus, and potassium levels were found, along with medium available nitrogen and organic matter levels. However, rapidly available phosphorus and rapidly available potassium were at deficient levels.[Conclusions]The content and distribution of soil nutrients in cultivated land are not only affected by natural factors such as geological background, soil type, altitude, pH, and soil depth, but also related to human activities, such as land use patterns.
Highlights: Total and available nitrogen (phosphorus and potassium) content and organic matter content in cultivated soil in Renhuai were systematically calculated, their geochemical grades were evaluated, and the influencing factors of their contents were systematically analyzed. The content and distribution of soil nutrients in cultivated land were not only affected by natural factors, such as geological background and soil type, but also related to human activities, such as land use patterns.

Abstract:This paper is the result of environmental geological survey engineering.[Objective]In the last glacial period, global climate was characterized by rapid, large-scale temperature cycles on a millennial scale. Such climate changes could be recorded in many geological materials such as ice cores, deep-sea sediments, Chinese loess, and cave stalagmites. The Black Sea is located in the transition zone between the North Atlantic and East Asian monsoon regions and has formed representative sedimentary records. This article is aimed at establishing the connections between the regional environmental changes of the Black Sea and the climate changes in the North Atlantic and East Asian monsoon area through the study of the sedimentary sequences of the Black Sea.[Methods]In this study, a 22.0 m core sample taken from Core GAS-CS12 in the northern slope of the Danube Canyon in the northwest of the Black Sea was analyzed for particle size, mineral composition, major elements, organic carbon, total nitrogen, and carbon and nitrogen isotopes.[Results]It was revealed that the core sediments of this section were deposited in the"Neoeuxine"lacustrine stage in the middle and late period of the last glacial period, and can be divided into 5 sedimentary units, corresponding to H4, H3, and H1 climate change events in the North Atlantic, the Last Glacial Maximum (LGM), and Bolling- Allerod climate warming event.[Conclusions]The connections between the sedimentary sequences and regional environmental changes of the Black Sea with the climate changes in the North Atlantic and East Asian monsoon area were established and this paper also confirmed that the millennium-scale climate changes of the last glacial period were highly consistent in the North Atlantic, East Asian monsoon area and their transition zones.
Highlights: Established the connections between the sedimentary sequences and regional environmental changes of the Black Sea; Provided reliable timescales for millennium-scale climate changes in the transition zone between the North Atlantic and East Asian monsoon regions.

Abstract:This paper is result of environmental geological survey engineering.[Objective]The representative dust deposit, the Wushan Loess located in China's northern subtropical river valleys, is a significant indication of environment near the Three Gorges region.[Methods]In this study, we collected samples from the Wushan Loess and analyzed rare earth elementary composition to discuss paleoclimatic significance of Wushan loess.[Results]Our new data show the four following implications. (1) The REE contents in each sample changes synchronously with little difference. The contents of LREE is much higher than that of HREE in each sample, suggesting the enrichment in LREE and loss in HREE. (2) The increasing of ∑REE with age in Wushan Loess is probably related to the strength of weathering the in Wushan Loess. (3) For samples from various depth, REE distribution patterns, δCe, δEu, La/Yb, Gd/Yb and ΣREE do not change significantly with depth. (4) The REE distribution patterns of all samples display negative slope, steep La-Eu curves and flat Eu-Lu curves, which suggests that certain differentiation between LREE and HREE has occurred. (5) The δEu values of Wushan Loess distributed within the interval of 0-1 on the vertical axis show obvious negative Eu anomalies andstable δCe values around 1. This implies that sediment in the upper Yangtze River did not suffer strong weathering in the period of Wushan Loess.[Conclusions]Wushan Loess have not been through intense weathering effect, the climate of its region while accumulation was colder and drier in the later period than it was in the earlier period, and no obvious change has been found in the source of its materials during the accumulation process.
Highlights: The climatic characteristics and the variation of provenance during the accumulation of the Wushan Loess are revealed by its rare earth elements (REE) concentrations.

Abstract:This paper is the result of environmental geological survey engineering.[Objective] Jinzhong Basin is located in the middle of the Fen-Wei Fault Depression Basins, in which the maximum thickness of the Cenozoic sedimentary layer exceeds 3800m. The establishment of the precise stratigraphic framework and the high-resolution sedimentary sequence of Jinzhong Basin is vital to understanding the evolution of the Fen-Wei Fault Depression Basins and the climate changes in North China.[Methods] In this paper, the chronology and sedimentology methods were used on the drill cores of the late Cenozoic standard borehole ZK01 (870.5m in depth) in the northeast of the Jinzhong Basin.[Results] The loose sediments in the borehole ZK01 were divided into 6 lithological formations. By means of magnetostratigraphy, the stratigraphic time frame was built with 13 normal polarity periods and 12 reverse polarity periods for the first time. The oldest Cenozoic sediments at the bottom of Jinzhong Basin is approximately 8Ma, moving the starting time of Jinzhong Basin activity forward about 3 Ma, from early Pliocene as previously believed to late Miocene. The late Cenozoic strata in this region are divided into Neogene Miocene Baodean Stage (N₁⁴) and Bahean stage (N₁⁵), Pliocene Gaozhuangian Stage (N₂¹) and Mazegouan Stage (N₂²2), Quaternary lower Pleistocene Nihewanian Stage(Qp¹), middle Pleistocene, upper Pleistocene, and Holocene.[Conclusions] Tectonic activity and climate change are the main controlling factors of the sedimentary environment in the basin, which results in two periods of large- scale lake development in the early Pliocene and middle- late early Pleistocene. In the early- middle Holocene, i.e., pre- Qin period (circa 2.5ka ago), rivers and lakes were in the coexistence stage in the basin; In the late Holocene (circa 2.5ka after), lakes atrophied, and rivers dilated; Then the lakes vanished in Ming and Qing period. Climate change and the impact of human activities are the main reasons for the eventual disappearance of the lakes in the basin.
Highlights: The development time of the Jinzhong Basin was firstly determined as in the late Miocene at 8.1 Ma by magnetostratigraphy. The lakes in the basin were mainly controlled by tectonism and climate in the early stage. Since the Holocene, climate change and human activities have caused the lakes to disappear.

Abstract:This paper is the result of hydrogeological survey engineering.[Objective]The detection of concealed fault structure in the city and its surrounding areas has an important impact on urban construction and economic development, which has attracted people's attention. According to the geological background and human conditions of the city, the key to the rapid and accurate location of concealed fault is to adopt appropriate methods, which must have the characteristics of rapid economy, green environmental protection and strong anti- interference ability.[Methods]Taking Lingui District of Guilin city as an example, in order to quickly and accurately locate the concealed fault F1 covered by the quaternary system, according to the geological background and the characteristics of the surface landscape of the District, a comprehensive geophysical and geochemical exploration method, such as CSAMT, soil mercury gas measurement, radon gas measurement, is adopted.[Results] It is found that the low resistivity anomaly is highly consistent with the high value anomaly of soil mercury gas and radon gas, It is speculated that the location of the multi method abnormal coincidence is the location of the concealed fault, and through drilling verification, the concealed fault structure and rich groundwater are exposed, which provides a basis for the search and development of deep geothermal water in this area.[Conclusions]It is obvious that CSAMT, soil mercury gas measurement and radon gas measurement are the technical combination to realize the rapid and accurate location of concealed faults in Guilin and its surrounding areas, and also provide reference for the detection of concealed faults in other areas.
Highlights: The rapid detection of concealed faults in cities and surrounding areas is carried out by using multiple methods of geophysics and geochemistry, which can verify each other and minimize the influence of human disturbance, it is obvious to the deep concealed fault structure.

Abstract:This paper is the result of oil and gas exploration engineering.[Objective]The differences in mineral composition, gas content and compressibility of shale lithofacies determine the development potential of shale gas. The division and evaluation of shale lithofacies is important to identify the sweet spot for shale gas exploration and development.[Methods]Based on drilling, core analysis, and test data, the comprehensive utilization of geological theory combined with ternary diagram of siliceous mineral, clay minerals, and carbonate mineral content are used to divide the gasbearing shale lithofacies of the Wufeng Formation and the lower part of Longmaxi Formation in Yichang slope of western Hubei province. The dominant lithofacies are also divided combining with the organic carbon content, gas content, and microscopic characteristics. The correlation between the abundance of organic matter, the content of siliceous minerals, the content of clay minerals and the shale gas content are carried out to establish the classification standard of gas- bearing dominant lithofacies of Wufeng- Longmaxi Formation.[Results]The dominant lithofacies in the study area is type II. The type II₁ (optimal) dominant lithofacies are mixed siliceous shale facies (S-2) and clay-bearing siliceous shale facies (S-3), located in the first sub-member of Longmaxi Formation and the upper member of Wufeng Formation, with thickness of 6 m. The type II₂ dominant lithofacies (suboptimal) is siliceous shale facies (S), located in the lower member of Wufeng Formation, with thickness of 4 m.[Conclusions]The Yichang slope belt and Fuling area have similar vertical evolution sequence of lithofacies, and the dominant lithofacies are both located in the Wufeng Formation and first sub-member of Longmaxi Formation. However, the thickness and quality of same shale lithofacies association are quite different. The subaqueous uplift of western Hunan and Hubei in the Rhuddanian stage is the main reason that caused the thickness and quality of the dominant lithofacies in Yichang area poorer than that in Fuling area.
Highlights: Established the classification standard of gas- bearing dominant lithofacies of the Wufeng- Longmaxi Formation, suggested the dominant lithofacies located in the first sub-member of Longmaxi Formation and Wufeng Formation.

Abstract:This paper is result of geothermal geological survey engineering[Objective] Geothermal resource in Huaiyang area belongs typical medium- low temperature geothermal resource of subsidence basin. Evaluation of geothermal resources in the Huaiyang area can provide insights into its exploitation and scientific management.[Methods]In this paper, we analyzed the geochemical and isotopes characteristics of geothermal fluids to explore their local geothermal field features and genesis.[Results] The results show that the deep thermal reservoirs are significantly affected by basement structure and faults characteristics. The geothermal gradient is higher (e.g., 3.75℃/100m in the Suzhuang area) along the boundary of faults than the other areas (e.g., 3.5℃/100m). The type of the geothermal fluids are dominated by Cl · HCO₃ · SO₄-Na, Cl·SO₄·HCO₃－Na and Cl·SO₄-Na. The main cation of the geothermal fluid is Na⁺ while the anions variou in types. The geothermal fluids were probably derived from the atmospheric "ancient water" of the Funiu Mountain in the western Henan province before 1952, with relatively weak rock-fluid reaction.[Conclusions]The major exploited geothermal reservoirs are placed at the Neogene Minghuazhen and Guantao Formations. The geothermal resources are mainly used for heating feeding, etc., which has greatly improved the local economy, Contribute to the realization of the "dual carbon" goal in the region.
Highlights: The relationship between geothermal gradient and geological structure in Huaiyang is analyzed; The sources of different ions in Huaiyang geothermal fluid and the main sources of geothermal fluid are discussed.

Abstract:This peper is the result of hydrogeological survey engineering.[Objective] Golmud is a rising city on the Qinghai- Tibet Plateau located on the southern edge of the Qaidam Basin. With the construction of various industrial parks and the establishment of the largest potash production base in China, the important role of groundwater resources has become more prominent. For the operation of industrial and mining enterprises and potash production bases, it is very important to find out the amount of underground water resources.[Methods] Based on data collection, dynamic long view, borehole pumping test, etc., the regional groundwater natural resources and allowable exploitation were evaluated by using the recharge sum method, section runoff method, excretion sum method and combined numerical simulation method, etc.[Results] The amount of groundwater natural resources in the alluvial fan of Golmud River is 199.8×10⁴ m³/d, and the allowable exploitation amount is 100×10⁴ m³/d.[Conclusion] Millions of tons of underground water sources exist in Golmud area. To ensure an adequate recharge of groundwater, the condition for sustainable and stable exploitation is that the planned exploitation of six water sources (built/under construction/planning) reaches one million tons. Finally, a million- ton groundwater source with B + C groundwater reserves of 100×10⁴m³/d is submitted.
Highlights: The regional groundwater flow model has been improved based on the latest detailed survey of groundwater; The method of "drought and rainy years" is used to set the inflow volume scene of the model, the regulation capacity of aquifers and the ability of continuous water supply in dry years have been fully tested, and the evaluation results have high credibility.

Abstract:This peper is the result of environmental geological survry engineering.[Objective] Baiyangdian Lake(BYD Lake)is the main ecological function area of Xiong'an New Area. In order to provide support for ecological restoration and protection of BYD Lake, we conducted a comprehensive survey on the environmental quality of the surface sediments in BYD Lake.[Methods] We collected 484 sets of surface sediment samples from Baiyangdian wetland, identified the geochemical characteristics of heavy metals in surface sediments of Baiyangdian lake, and used multiple methods such as geo- accumulation index method and potential ecological risk index method to evaluate the ecological risk of heavy metals.[Results] The results indicate that the average content of most heavy metal elements in the surface sediments of BYD Lake is significantly higher than the soil background value in Hebei Province. The entrance of Fuhe river and Baigou river are the main rich areas of heavy metal elements, rivers are the main sources of heavy metals in the surface sediments of BYD Lake. The distribution area of clean and pollution-free grade is 144.54 km², accounting for 96.68% of the total surface sediment distribution area. The pollution degree of each heavy metal can be ranked as Cd > Cu > Hg > Pb > Zn > Ni > Cr > As. The pollution degree of Cd is mainly moderate, the pollution degree of Cu is mainly light and clean, and the pollution degrees of other elements are mainly clean and pollution-free. The potential ecological risk of heavy metals in the surface sediments of BYD Lake is mainly mild and moderate, and the potential ecological risk level of heavy metals near the river entrance is higher than that of other areas. The potential ecological risk levels can be ranked as Nanliuzhuang > Shaochedian > Xiaobaiyangdian > Wangjiazhai > Zaozhadian > Laowangdian > Chiyudian > Fanyudian.[Conclusions] The environmental quality of the surface sediments in BYD Lake is generally good, with heavy metals exceeding the standard in some areas. The environmental quality of surface sediments in Baiyangdian is generally good. There are potential ecological risks of heavy metal pollution in Nanliuzhuang and other areas, and Cd is the main pollution element.
Highlights: Geo- accumulation index method and potential ecological risk index method were used to evaluate the heavy metal pollution degree and ecological risk of surface sediments in Baiyangdian Wetland. The analysis of heavy metal geochemical characteristics combined with principal component analysis revealed that the heavy metal pollution in surface sediments were mainly from river input.

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