The therapeutic and health benefits of geothermal water are widely recognized; its specific chemical components, particularly fluoride (F-) and the increasing levels of nitrate (NO3-), have raised growing concerns about potential risks. Nevertheless, scientific understanding of the enrichment mechanisms and associated health threats of F- and NO3- in geothermal water remains limited in Northwestern Shandong Province (NWS). This study systematically investigates geothermal waters in NWS by integrating hydrogeochemical analysis with deterministic-probabilistic health risk assessment models. The objectives are to reveal their hydrochemical characteristics, elucidate the enrichment mechanisms of F- and NO3-, and evaluate their potential non-carcinogenic health risks to humans. The results indicate that the enrichment of F- in NWS geothermal water is primarily governed by natural hydrogeochemical processes, manifested as the synergistic effects of fluoride dissolution, calcium-bearing mineral precipitation, alkaline environment, and positive cation exchange. In contrast, the elevated NO3- levels are clearly attributed to anthropogenic influences such as agricultural activities. Under the conventional exposure scenario of skin contact (e.g., bathing), both deterministic and probabilistic risk assessments consistently demonstrate that the non-carcinogenic risks for adults and children are generally acceptable (mean HI < 1, with zero exceedance probability). However, the critical risk arises from non-routine exposure pathways: assessment of accidental geothermal water ingestion reveals a significantly elevated non-carcinogenic risk for children, with the HQ exceedance probabilities (> 1) for F- and NO3- reaching 44.25% and 43.68%, respectively, whereas the corresponding probabilities for adults are only 2.6% and 12.16%. Sensitivity analysis indicates that exposure duration and frequency (exposure opportunity) are the primary controlling factors for adults, whereas children exhibit extreme sensitivity to body weight parameters, with their lower exposure dose per unit body weight significantly amplifying health risks. This study reveals that accidental ingestion (especially by children) constitutes a significant but long-neglected health threat. Accordingly, it is recommended that geothermal resource management prioritize protective measures and educational interventions targeting children in areas lacking public awareness.

Sustainable utilization of sandstone geothermal resources is a worldwide challenge due to limited natural recharge and rapid aquifer clogging associated with reinjection of return water back into reservoirs. In the Dezhou area of the North Shandong Plain (NSP), China, technical solutions for successful reinjection have been developed and applied based on nearly 30 years of production experience from the Guantao geothermal reservoir. These solutions include drilling large-diameter reinjection wells, filtration systems, oxygen-free configuration, back-pumping, and acidification. To further investigate the reservoir properties, a pumping test, three reinjection tests, and a tracer test were carried out in a dedicated experimental field setup in Dezhou, which included one regular diameter production well and one large diameter reinjection well. This study integrates effective reinjection technologies with long-term sustainability assessment, providing a comprehensive framework for managing low-temperature sandstone geothermal systems. Based on long-term water-level monitoring data and lumped parameter modelling, a sustainable yield assessment of the reservoir in the urban Dezhou area has been performed, with the deepest permissible water level at 150 m below ground surface over a 100-year time frame. The results suggest that reinjection is the dominant factor influencing sustainability. When the reinjection rate approaches 90%, the sustainable yield corresponds to an average value of 1300 L/s during the space heating period and 500 L/s annually. Using volumetric energy balance calculations, the average thermal energy loss over 100 years of reinjecting cooled return water is estimated to constitute 3% and 8% of the total energy stored relative to the volumes of the closed and open lumped parameter models, respectively. This indicates that the cooling assessment of reinjection should further concentrate on the cooling distribution in the reservoir and the decrease in reservoir temperature in particular locations. This study emphasizes the importance of integrating reinjection strategies with sustainability assessments and highlights the need for continued long-term geothermal resource management research for porous sandstone reservoirs.

Carbon capture and storage (CCS) technology is a crucial and effective tool to achieve China’s dual carbon goals. The primary locations suitable for underground CO2 storage include depleted oil and gas reservoirs, deep saline aquifers, and deep unmineable coal seams. Among these, deep saline aquifers are widely distributed in most of the world’s sedimentary basins, and they offer significant advantages—such as substantial storage capacity, well-established technology, high safety standards, and cost effectiveness—making them crucial geological reservoirs for carbon dioxide storage. In comparison to foreign countries’ projects on CO2 capture, utilization, and storage (CCUS) technology, China’s initiatives have been implemented more recently, and no research has been conducted on the geological storage of CO2 in the deep saline aquifers within the study area. In this study, we systematically analyzed the key factors for the geological storage of CO2 in saline reservoirs within the northwest plain of Shandong Province: the Paleogene Shahejie Formation saline aquifer, and the lower reservoir of the Minghuazhen Formation saline aquifer located east of the Zhanhua–Lijin–Dongying line. The CO2 geological storage potential of these aquifers was assessed using the evaluation methodology of the United States Department of Energy, yielding a result of 30.355 billion tons. An evaluation index system of CO2 geological storage suitability was established. Evaluation indices for regions in the study area were assigned according to this evaluation index, and the score and grade of each unit were obtained. The results indicated that the Huimin latent fault depression, Dongying latent fault depression, Dezhou latent fault depression, and Dongming–Shenxian latent fault depression are suitable prospective areas for CO2 geological storage in the saline aquifers of Shandong Province’s northwest plain.

Objectives: Dagu River basin is an important water supply source for Yantai City and Qingdao City. This paper is in order to study the water chemical characteristics and genetic mechanism of Dagu River basin.Methods: Water samples, including 35 groundwater and 5 surface water, were collected from the upstream research area of Dagu River basin. Hydrogeologicalinformation, Piper terraph map, descriptive statistics method,Gibbs diagram and ion ratio were used to analyze the hydro-chemical characteristics and explore their evolution mechanism of the study area.Results: The results shown that the groundwater in Dagu River basin is weakly alkaline. HCO 3 - ,SO 4 2- and Ca 2+ , Mg 2+ were the dominant anions. All of most of samples belonged to HCO 3 - 、SO 4 2- —Ca 2+ 、Mg 2+ water type.The hydro-chemical characteristics of Dagu River Basin are affected by water—rock cation exchange, rock weathering and dissolution are the main controlling factors. Moreover, the cation exchange is active.Conclusions: Na + 、K + 、Cl - and metasilicic acid mainly comes from the dissolution of silicate rock, while Ca 2+ ,Mg 2+ and SO 4 2- mainly come from the dissolution of carbonate rock, which is significantly higher than that from the dissolution of evaporite rock. Human activities have a great influence on the chemical characteristics of groundwater.Human activities, such as agricultural planting and aquaculture, generally lead to high NO 3 - concentration in water,while human activities aggravate the weathering and dissolution of silicate minerals. The concentration of metasilicate increases. The concentration of metasilic acid in more than 74% of the water samples reached 25mg/L.

AbstractThere are 1,000 geothermal wells with depths of 1500–2000 m drilled into the upper Tertiary sandstone geothermal reservoir in the Guantao Formation in the North Shandong Plain, which support about 61 million square meters of domestic space heating. Concerning the large-scale exploitation of the Guantao Formation geothermal reservoir and its important role in clean space heating, it is essential to fully understand the characteristics of the geotemperature, geothermal water flow, and hydrochemical features, especially the heat accumulation and geothermal water enrichment mechanism. Based on the data from pumping tests, temperature logging, water level measurements, and hydrochemistry and isotope sampling and analysis, in this study, the heat sources and accumulation, water sources, and enrichment mechanism of the sandstone geothermal reservoir in the Guantao Formation were explored. The geothermal gradient of the cap rocks and the reservoir’s temperature revealed that the geothermal temperature fields are controlled by fault structures, and the relative high temperature zones are distributed in the area where the uplifts and deep heat-controlled faults converge. The geothermal water-rich area is located in the ancient river channel zone. The closer the water-rich area is to the ancient river channel belt, the deeper and coarser the buried conglomerate aquifer is, and the better the water-rich condition is. The best water-rich areas are found in the alluvial fan of the ancient channel belt.

鲁北平原不同构造单元,具有不同温度、矿化度、特殊化学成分、富水性的地热资源.其中馆陶组热储是区内资源最丰富、开采利用程度最高、规模最大,为最具经济开采价值的热储.正确认识其地温场、水化学场特征及地热水富集机理,成为目前人们最为关心的问题.本文根据对馆陶组热储盖层地温梯度、热储温度变化特征的分析,结合地质构造条件,揭示了地温场温度受断裂构造影响,高温区主要分布在武城-高唐-陵县、宁津-庆云、沾化-孤岛、高青-博兴等凸起区与断裂交汇部位.区内馆陶组地热水化学类型以Cl-Na为主,其次为Cl·SO4-Na及SO4·Cl-Na型,矿化度4.07～18.52g/L,pH值7.14～8.1,地热水中含有大量人体健康所需的微量元素.分析认为,区内馆陶组地热水成因为大气降水,蒙脱石向绿泥石转变是地热水中贫钾、贫镁原因,馆陶组热储地热水总体流向为西南流向东北,在各县市城区地热水由四周向城区漏斗中心运移.本文根据地热钻探揭露馆陶组底砾岩深度、厚度及地热井水位、单井涌水量等大量数据的分析,揭示了鲁北平原馆陶组地热水古沉积相环境,并划分出两个大的古河道带:即临清—武城—德州—陵县一线古河道带和沾化—河口—仙河一线古河道带.前者后期受南部高唐凸起和东部埕子口-宁津潜断隆控制,在德州—陵县一带形成了范围较大、岩性颗粒较粗、厚度较大的冲洪积扇区;后者主要受西北部刁口潜凸起、义和庄潜凸起与南部无棣潜凸起控制,在河口—孤岛—仙河一带形成了较大范围岩性颗粒较粗、厚度较大的冲洪积扇区.在下游受陈庄凸起、青坨凸起影响,将古河道带分叉为两部分,南部古河道带分布在利津—东营一带.地热水富水规律与古河道带一致,富水区主要分布在两个古河道带区域,单井涌水量一般大于85m3/h,且距古河道带越近,含水层砂砾岩埋藏越深,颗粒越粗,富水条件越好;反之,富水条件越差.在古河道带冲洪积扇部位富水条件最好.

Nowadays, how to determine the maximum allowable drawdown of layered pore and fractural geothermal reservoir is still unsettled. Based on the control ofland subsidence, taking Dezhou city as an example, through anal-ysis on land subsidence and deep underground water, a numerical model has been established for the maximum al-lowable drawdown ofgeothermal water and the date of maximum allowable drawdown of the geothermal water mining of Neogene Minghuazhen group and Guantao group and Eogene Dongying group is calculated. Finally, the maximum allowable drawdown range of similar area is determined. This study has important practical significance and theoreti-cal reference value for the study of maximum allowable drawdown of layered pore and fractural geothermal reservoir and the sustainable development and utilization of geothermal resources.

Through investigation and collecting samples of different deep karst geothermal water,isotope δD,δ18O and radioactive isotope 14C have been determined,and the origin,age,property of geothermal reservoir and hydraulic connection have been analyzed.It is showed that the origin of deep karst geothermal water in Shandong is air precipitation.Its formation age is antique,recharge way is long and runoff velocity is slow.Hydraulic connection of the same strucute in coastal area and lonely island zone,Qihe and Liaocheng area is very close,while it is weak in other places.

Abstrct:Deep karst thermal reserves distribute in Jiyang depression area,convex(latern)area of Linqing depression and Luzhong uplift area,southwestern latern uplift area in Shandong province and Yishu fault belt.Its distribution square is about 44000km2,and the distribution ranges are the same with the strata in Cambrian-Ordovician period.Deep karst reserves can be divide into deep crack-karst reserve and deep karst-crack reserve with the characters of layer type and strip type.On the basis of previous research results and the ideas of the authors,burying,distribution,water quality,characteristics of geothermosite,developing law of deep karst and the forming condition of geothermal fluid have been analyzed.It will provide help for development and utilization of thermal reserve.

According to lots of the former information,distribution and development characteristics of deep karst thermal reservoir in Shandong province have been analyzed.The delineated scope of deep karst geothermal reservoir is 44000km2,including 12 geothermal areas in total.Karst types are karst-fissure type and fissure-karst type.It has a guiding significance and reference value for further study,exploration and development and utilization of deep karst geothermal reservoir in Shandong province.

Data entry is an onerous work in groundwater dynamic monitoring database.Traditional manual method has the characteristics of low efficiency and some mistakes.In this paper,a new automatic entry method by using VBA program has been introduced.It will greatly improve the efficiency and reduce errors.

Due to massive exploitation of geothermal water in Dezhou city in many years, geothermal water level continued to decline, and formed a geothermal water depression cone centered in Dezhou City. Based on the analysis of water dynamics and geothermal exploitation rate in Guantao geothermal reservoir, the relationship between the amount of geothermal water withdrawed and water dynamics has been verified, and the impact of human activities have been furtherly revealed, and the correlation equation between the amount of geothermal water withdrawed and water dynamics has been set up. Through analysis on the e- quation trend, a warning exploitation rate of geothermal water in Guantao reservoir is put forward. It will provide a rational and scientific basis for the sustainable development and utilization of geothermal resource.

On the basis of collecting and analyzing the newly gained information,major ecological environment problems occurred in the downstream of the Yellow river are introduced in this paper,such as water pollution,water resource deficiency,ground subsidence,ground crack,ground collapse,sand liquefaction,soil salinization and instability of the dyke.Countermeasures for protecting ecological environment problems are put forward as well.It will have a high reference value in national resource exploitation,flood control,disaster protection and prevention,and eco-geological environment protection.

Setting geothermal rejection in Dezhou districts as an example,effects of geothermal rejection to water quality,pumping rate and water temperature and elements which will effect re-injection efficiency are analysed.It is proved that the structure of re-injection well,geothermal reservoir characteristics,re-injection pressure and re-injection are major elements which will effect re-injection effect.Relationship between re-injection rate and re-injection pressure are determined as well in this paper.Through this experiment,it is proved that re-injection is an effective method in soluting problems caused by geothermal resource exploration.

The groundwater petroleum contaminant remediation effect by air sparging was investigated in an oil field. The results show that the soil geological situation has great influence on the air distribution, and the shape of air distribution is not symmetrical to the air sparging (AS) well as axis. The influence distance in the left of AS well is 6 m, and only 4 m in the right. The petroleum removal rate can reach 70% in the zone with higher air saturation, but only 40% in the zone with lower air saturation, and the average petroleum removal rate reaches 60% in the influence zone for 40 days continuous air sparging. The petroleum components in groundwater were analyzed by GC/MS (gas chromatogram-mass spectrograph) before and after experiments, respectively. The results show that the petroleum removal rate has relationship with the components and their properties. The petroleum components with higher volatility are easily removed by volatilization, but those with lower volatility are difficult to remove, so a tailing effect of lingering residual contaminant exists when the air sparging technology is adopted to treat groundwater contaminated by petroleum products.

In order to study soil recovery quality by using air sparging method, 13 days experiment is carried out in the field. Its is proved that adsorption type and residual type oil hydrocarbon in soil can contacted each other by using air sparging method, which can get rid of oil hydrocarbon through volatiliztion and aerobiont plants. It provides scientific basis for recovering plants polluted by oil.