The Altay area is an important rare metal, non-ferrous metal, gemstone and industrial muscovite metallogenic belt. Based on the 1︰1 000 000 geochemical mapping data across the boundary between China and Mongolia, the authors calculated background values of 69 elements in the catchment sediments. The median values of the dataset after disposable eliminating outliers from the original dataset with X±3S as the critical values were used as estimated values of the geochemical background values. The results show that the geochemical distribution of elements in different geotectonic units is different due to different geological backgrounds. These background values can be used as basic data for comparison for further development and utilization of geochemical mapping data across the boundary between China and Mongolia.

With the progress in the study of ultra-high sensitivity and high precision magnetometers, magnetic gradient measurement has become possible, and is currently widely used in the field of engineering geophysical explorations such as non-explosives detection. In order to understand the difference between the measured magnetic gradient and the calculated magnetic gradient and its application effect on the metal ore, the authors carried out a 1∶5 000 magnetic gradient measurement test in the Laikluck copper-iron deposit in East Junggar, Xinjiang, The authors compared the difference and similarity between the measured magnetic gradient and the calculated magnetic gradient. It is found that the macroscopic trend of the measured magnetic gradient and the calculated magnetic gradient are basically the same, but there are differences in the anomaly details; when the point distance and the line spacing are not equal, the calculation of the magnetic gradient line is effective. In a certain direction, the magnetic anomaly has a tendency of lengthening along the direction of the line; the difference between the calculated gradient and the measured gradient in different intensity anomalies is the largest, especially the vertical gradient. The measured magnetic gradient has a relatively obvious detection advantage for burial shallow anomalous geological bodies, and can obtain more geological body information. For low-relief anomalies, the distance between the probes is limited due to the topographical conditions, and the magnetic anomalies are weak. Combined with the analysis of the exploration results of the Laikluck magnetite, it is considered that the measured magnetic gradient is sensitive to local anomaly detection, and the surrounding rocks are magnetic deposit such as volcanic rock. The geomagnetic gradient measurement is beneficial to delineating the magnetic boundary. The two-dimensional and three-dimensional vector of the measured magnetic gradient can also distinguish the nature of the anomaly and provide an indication for the prospecting prediction.

The search for deep buried iron deposits is a very complicated exploratory study. The current difficulty is that the ferromagnetic anomalies are small and submerged in large magnetic intrusive rock masses. It may cause large deviations and increase the risk of exploration. With the rapid development of computer technology, large-scale three-dimensional inversion has become a reality. This paper uses GMES-3DI commercialization software to automatically invert the area magnetic data of Qihe-Yucheng area in Shandong Province, and obtains the magnetic susceptibility of underground space in this area. Based on the distribution and combined with the existing geological data of boreholes, the authors revealed the characteristics of the magnetic susceptibility contours with high value traps in the presence of iron ore, with the trap center being about 500 m shallower than the actual orebody position. Based on this feature, the authors used the three-dimensional magnetic susceptibility data retrieved from the exploration area to search for areas with high magnetic anomaly traps in the north-south and east-west directions and, as a result, delineated two relatively reliable prospecting targets.

The Neihuang-Xunxian area in Henan Province is located in the Archaean basement uplift area, and has good gravity and magnetic anomalies. It has favorable conditions in the search for sedimentary metamorphic magnetite deposits. However, since the 1970s, due to the limitations of shallow prospecting knowledge, no breakthrough has been made in prospecting. Aimed at the target area of deep magnetite prospecting, the authors detected the plane position (center and boundary) of the concealed magnets in the study area by central recognition technology (analytical signal amplitude ASM) and edge recognition technology (NVDR-THDR), obtained the burial information of the concealed magnets in the study area by Euler deconvolution, and analyzed the homologous characteristics of gravity and magnetic anomalies in the study area by correlation coefficient. Combined with known boreholes, 2.5D fitting inversion of key magnetic anomalies in the study area was carried out, and the scale and spatial distribution characteristics of the concealed magnets were determined. The results show that the buried depth of the concealed magnets corresponding to the main magnetic anomalies is 500~1 200 m, and the ore-bearing property in the deep part is better than that in the shallow part, so the prospecting potential in the deep part is great. On the basis of comprehensive geological and mineral conditions, two deep prospecting target areas of Wagang-Yujian and Nanzhangbao magnetite ores were delineated. It is suggested that they should be the key directions in further deep prospecting with the purpose of achieving a breakthrough in deep prospecting in this area as soon as possible.

Aimed at tackling the problems of low efficiency and the need of high data quality of IP observation methods in borehole, the authors developed a new device of borehole IP prospecting in this paper. The device can be used to measure the polarization field potential (V), potential difference (ΔV), secondary field potential (V₂), potential difference (ΔV₂) and time information (T) simultaneously by full waveform electrical method, and then obtain various IP parameters. In order to test the validity of the method, the authors studied the application of full waveform array IP to a copper-gold deposit in Anhui Province, obtained the connectivity of the drilled orebody, and determined the direction and distribution range of the orebody. The application results show that this bolehole IP observation of full waveform array method has high efficiency and strong anti-interference capability.

In the coverage area, it is very difficult to carry out the conventional geological work , whereas the high-precision gravity and magnetic survey methods can quickly and effectively divide the buried faults and determine the rock boundary, which provides important assistance for prospecting in the coverage area. With the Weishan iron-copper deposit reconnaissance in Wuwei County of Anhui Province as an example, the authors divided the faults and determined rock boundary in the pre-investigation area through the processing and analysis of gravity and magnetic anomalies. Combined with geological features, two gravity and magnetic anomalies with large potential for prospecting were screened where a 40 m rich iron orebody with a TFe grade of about 52% and a mFe grade of about 38% was found by drilling. Therefore, the effectiveness of the method is confirmed, and this result also has certain guiding significance for the prospecting work in the eastern marginal coverage area of the Luzong volcanic basin where the investigation area is located.

The Carboniferous volcanic reservoir in Wulungu depression is an important target stratum for hydrocarbon exploration in Junggar Basin.However,due to its deep burial,complex lithology and strong late reformation,it is difficult to depict the distribution of volcanic rock masses by relying on the previous two-dimensional seismic exploration technology.Mainly based on the seismic data collected by low frequency vibroseis,the authors studied the distribution characteristics of Carboniferous volcanic rocks in the northern part of Wulungu depression.In view of the advantages of low-frequency information in deep-layer imaging and the good reflection of stacked section to structural trends,low-frequency stack section was used to identify wave field,which can guide migration section interpretation.Then by combining geological,seismic and drilling data,research on volcanic rock identification was carried out.The seismic response characteristics of volcanic facies in this area were summarized.The distribution of volcanic rocks was identified and characterized by means of seismic reflection characteristics and seismic attribute analysis.A low-frequency seismic identification method for volcanic reservoirs suitable for deep-buried complex lithologic conditions is explored.It provides a basis for Carboniferous oil and gas exploration in this area.

Due to the restriction of geological detection equipment and tidal time,the degree of geological exploration in coastal tidal-flat areas is low and the detection accuracy is insufficient,which cannot meet the demand of high-precision geological survey in this area.Conventional shallow seismic exploration technology can effectively detect Quaternary bottom interface and internal horizons in the coastal tidal flats,but it has a complex and inefficient data-acquisition equipment,which directly restricts the progress of seismic exploration in this area.Therefore,this paper proposes a high-precision shallow seismic detection technology which is suitable for coastal tidal-flat areas.It can effectively solve the above difficulties by making full use of the surface characteristics in coastal tidal flats and using modified towed seismic detection equipment to acquire field data,thus providing a new idea for seismic detection in this area.At the same time,a set of seismic signal extraction process and method combinations are made for coastal tidal-flat areas,which can retain effective seismic reflection information to the greatest extent and restore the underground geological structure.The results of the application show that the technology can provide reliable data support for the fine division of subsurface in the coastal tidal flats.

The Late Palaeozoic volcanic rocks are well developed in Wangyangtai area of Balekkun, Xinjiang. NW- and NWW-trending tectonic fracture zones are extensively developed, and the mineralization and alteration of malachite and silicification are strong. In order to further guide the copper ore prospecting work in the area, the authors identified 16 single element anomalies such as Au, Ag, and Cu through the comprehensive processing of data obtained from the collection and test of samples from 1∶50,000 stream sediments in this area. According to the geochemical characteristics of various elements, the correlation of elements and the associated combination relationship in the evaluation area, the authors divided the elements into five types, i.e., chacophile-siderophile elements, low-temperature elements, sulfophile elements, high field strength elements and gold elements. According to the combination of abnormal elements and in combination with the geological background of metallogenesis, 14 comprehensive anomalies were identified, classified and ranked on the basis of the magnitude of their prospecting significance, and the important comprehensive anomalies with greater prospecting significance were evaluated and verified. Based on the results of anomaly verification, the rule of abnormal distribution and the geological background of mineralization, the HS-5 comprehensive anomaly was selected as the best copper prospecting target area, which provides an important basis for the geological prospecting work in the area in the future.

By using regional geochemical data in combination with regional geological conditions to determine geothermal prospect areas, researchers can evaluate the potential of geothermal resources. Data research shows that geochemical characteristics of geothermal areas of different genetic types in Jingjinji are different. The lower mild anomalies of As, Sb, Bi, Hg, F, Li, Sn, U, Th and other elements may have corresponding indication effects to different types of geothermal areas. Various types of geothermal geochemical indicator elements are as follows: Li-F-As-U for volcanic rock type, Sn-Bi-Li-Th-As for invasive rock type, F-Th for metamorphic rock type, and Hg-Li-As-U for sedimentary rock type. According to the correlation analysis, the regression equation can be established between the geothermal water temperature T and the sediment element content in the water system sediments. It is indicated that the alkaline magmatic hydrothermal activities and the associated products of molybdenum and silver mineralization are heat-producing and thermal-conductive rock formations, whereas the metamorphic rocks and the sedimentary rocks constitute the insulation and heat preservation layers. According to the spatial distribution of the combination of geochemical anomalies of the indicator elements, a total of 50 geopotential or dry-hot rock prospect areas were delineated in bedrock areas of Jingjinji. These prospective areas show NE, NW and EW distributions, which are closely related to the deep huge faults and the Yanshanian medium-basic magmatic rocks. Meanwhile, they are consistent with the distributions of geothermal anomalies in the plain areas. In recent years, geothermal exploration activities show that this result has played an important guiding role.

It is difficult to predict the thin sand beneath the coal seam because of the influence of the strong shield.It is difficult for conventional wavelet decomposition techniques to decompose stable wavelet sets,and even the decomposed wavelet sets have no definite geological significance.In this paper,a new seismic meme inversion is proposed,which uses the similarity of seismic waveforms as an indicator factor to drive broadband logging curve simulation and realize high resolution inversion.Firstly,the dynamic clustering analysis of seismic waveform is realized by singular value decomposition,and the sample set of seismic waveform and well curve characteristics is established.Then the common structure in the sample is determined as the initial model in the wavelet domain,and the inversion results with high resolution are obtained by modifying the initial model according to the inversion of the actual seismic waveform structure under the constraint of the Bayesian framework.Through forward modeling and Jurassic case study in Junggar Basin,it is concluded that seismic meme inversion overcomes the limitation of seismic vertical resolution and can better predict thin sand affected by strong shield.Seismic meme inversion provides a new way for predicting thin sand affected by coal shield in Jurassic in Junggar Basin,Ordos Basin and Turpan-Hami Basin.It has a wide range of applications and important practical significance.

In the field prospecting work, the most important thing for geologists is to wait for the data of sample test results. The test period is generally relatively long. In the exploration work of the Dalu manganese deposit, the author's group quickly surveyed the drilling cores of the manganese deposit by X-ray fluorescence instrument. It is found that the measurement data of this method have high accuracy in judging the enriched strata of manganese ore and the interpretation accuracy of orebody. Moreover, the instrument is precise. After calibration, the results of measurement are compared with those of laboratory data. The degree of approximation is very high. Especially for manganese ore (chemical) layer whose grade is more than 5%, the error between the results of measurement and laboratory results is generally less than 7%. It has objective and efficient guiding significance for orebody confirmation, core sampling section and sampling length determination in the field.

Located on the north margin of Nakhon-Khorat basin, the Vientiane Basin of Laos has one of the largest solid potash deposits in the world. The main orebody is closely related to thick-bedded Carnallite, and locally associated with thin-bedded potassium. The authors' company has completed 3 AMT profiles in a mining area in northeastern Vientiane Basin. The 2D inversion results reflect directly the fluctuation of salt beds in Tagong Formation and the distribution of structures. The spherical high-resistivity uplifts exist in the western part of Line L2 and the central and western part of Line L3. Drilling detected the spherical high-resistivity uplift as the salt bed with salt layer becoming shallower and its thickness becoming larger. The structures on both sides of the uplift area are well developed. AMT 2D inversion model basically reflects the salt layer uplift completely. The roof burial depth of salt rock exposed by L1 line boreholes is in good agreement with the result of two-dimensional electrical model inference. In a word, through the comparison between the AMT 2D inversion models and the data of boreholes near the profiles as well as the results of geological and geophysical prospecting, it is shown that the 2D electrical model obtained by AMT reflects the occurrence state of salt beds and the location of structural development. Therefore, the characteristics of salt beds and the structures reflected by AMT inversion models can provide the evidence for the optimization of prospecting target areas, selection of drilling sites and the metallogenic research. The results obtained by the authors provide a positive reference for the selection of geophysical methods for potash mineral exploration in the future.

In recent years,offshore OBC and OBN technology has achieved rapid development.Whether it is OBC acquisition or OBN acquisition,many new equipment and methods were developed.Based on the latest research results and published papers,this paper summarizes the development history and research status of offshore OBC and OBN technology,and summarizes the technology and equipment for offshore four-component seismic exploration and acquisition,as well as processing and interpretation techniques.It is considered that the seabed multi-component seismic is the development trend of marine seismic,because it has the advantages of multi-component data, wide azimuth and wide frequency compared with the marine tow streamer.But the processing of data and conversion wave need to be researched.Now offshore oil and gas exploration is in the stage of complex structures and lithologic reservoirs,as the cost of submarine seismic decreases and the processing technology advances, it will be get more applications.

Gaussian beam migration (GBM) is a ray-based seismic imaging method,which can handle multi-arrivals and has good imaging accuracy.However,two problems should be taken into consideration when this method is used in complex topographic conditions:First,the original local plane wave decomposition method has insufficient calculation accuracy,which affects the imaging quality of low signal-noise ratio data.Second,the ray beam propagator is the most important factor for migration accuracy.With the enhancement of the propagation distance,the Gaussian beam width increases rapidly and cannot ensure the imaging accuracy of the near surface and depth structures at the same time.In addition,the insufficient coverage of the Gaussian beam in the shallow part of the model might affect the imaging quality of this region.In order to solve the above problem,the authors apply wave decomposition technique based on compressed sensing theory to the complex surface in Fresnel beam migration.It not only effectively improves the precision of local plane wave decomposition,but also solves the problem that the width of Gaussian beam operator is increased quickly with the increase of propagation distance according to the Fresnel beam operator.Typical numerical examples prove the validity and stability of this method.

The gamma spectrometry logging is widely used in survey of radioactive, metallic and non-metallic deposits and stratigraphic correlation. In order to obtain a wider energy range of gamma spectra, the authors designed the wide-energy spectra logging system with the combination of LaBr₃ and BGO detectors. To determine the optimal selection principle of the wide-energy range gamma spectra logging system, the authors built a model of wide-energy spectra logging system on MCNP to simulate the measured gamma spectrum. The simulation shows that the best effect is achieved when the shield is made of tungsten-iron-nickel alloy. When the shield thickness reaches 14 cm, simulation shows better shielding effect for the distal detector. The effect for the proximal detector is close to the distal one when its relative position is 35 cm or more. The effect of changing the position of the neutron source on the thermal neutron shielding is limited. As a thermal neutron shield, boron could achieve obvious shielding effect with 0.2cm layer. The effect of fast neutron can be reduced by increasing shield thickness and the distance between the proximal detector and the shield.

In recent years,the rapidly developed passive Rayleigh wave technology has the advantage of strong anti-interference capability and less limited construction conditions by using environmental noise as the source,which is more suitable for exploration in urban areas.However,the key factor affecting the imaging accuracy of the passive source method is the extracting quality of the dispersion curves.The current passive source Rayleigh wave method mainly uses the Aki formula to calculate the Rayleigh wave dispersion curve according to the relationship between spatial autocorrelation and time domain cross-correlation.This method has a good extraction effect for long-period observation data (for several months or more).Nevertheless,for practical engineering applications,it is desirable that the data observation period is as short as possible (such as one day or several hours).Under this circumstance,it will lead the zero points of the cross-correlation spectrum to increase or disappear,which will bring errors in the extraction of the dispersion curves when the Aki method is used to pick up them.Aimed at solving this problem,the authors put forward a set of quality control processes,such as using different normalization methods,selecting different window lengths for cross-correlation operations,setting Gaussian filters to filter cross-correlation functions,and selecting spectral zeros,to improve the extracting quality of dispersion curves.The authors combined certain evaluation criteria to verify the reliability of the dispersion curves and achieved the purpose of controlling the quality of the dispersion curves extraction.The passive source numerical simulation of theoretical model testing and the actual field noise data processing in Fengxiang County of Shaanxi show that the quality control method in the dispersion curve extraction is feasible and effective.This study has certain reference value and practical significance for the dispersion curve extraction of passive source Rayleigh wave method.

Using the electromagnetic field formula of horizontal electric dipole source on the surface of layered model, the authors calculate electromagnetic field components of different transmitting and receiving distances and different layered geoelectric models systematically. The method for identifying frequency response by circular cross-correlation method and calculating the whole zone apparent resistivity is given. The apparent resistivity of the whole zone is calculated by using the E_x component of horizontal electric field and the H_z component of vertical magnetic field. Compared with the Cagniard apparent resistivity of layered model of magnetotelluric sounding and the Cagniard apparent resistivity of controlled source audio magnetotelluric sounding, the whole zone apparent resistivity of E_x component of horizontal electric field and the H_z component of vertical magnetic field can well reflect the geoelectric characteristics. Moreover, the whole zone apparent resistivity of the vertical magnetic field with the H_z component has similar frequency response characteristics with the Cagniard resistivity of the layered model of magnetotelluric sounding in low frequency band. As for deep buried basement, the whole zone apparent resistivity of the H_z component can respond well under the condition of small transceiver distance. The frequency of the vertical magnetic field component entering the near zone is lower than that of the horizontal electric field entering the near zone, which proves the proposed means is more conducive to deep exploration under the condition of small transceiver distance.

The time-lapse resistivity method can be applied to engineering and environmental problems such as monitor groundwater contaminant transport, measure slope stability. In this paper, the normalized data inversion result of the time-lapse resistivity method was used to identify the subsurface structure of small resistivity changes. First, the data ratio normalization was adopted in which the initial data serve as the background data to normalize the data at other times. Next, the separate nonlinear conjugate gradients (NLCG) inversion result of initial data, time-lapse data and normalized time-lapse data were implemented. The same inverted parameters and homogenous half space model that was taken as the reference model were applied in all synthetic data examples. The inversion results show that the normalized data inversion results can effectively distinguish the small changes of resistivity relative to the background, but the conventional resistivity inversion almost cannot recognize it.

The induction magnetic field sensor is widely used in geophysical electromagnetic apparatus. Because of the physical principle, the noise level of the magnetic field sensor is proportional to its length and volume, the length is usually 800~1 400 mm, and the mass is 3~6 kg. In this study, a compact and flux concentrator was developed. The length is less than 240 mm, the diameter is 110 mm, and the mass is 3kg. Its length is approx. 30% of traditional AMT magnetic field sensors, the frequency band is from 0.1 Hz to 10 kHz, and the equivalent magnetic field noise level is 0.8 pT/ \sqrt[]{\mathrm{Hz}} at 1Hz. The three magnetic field sensors with the same parameters are mounted vertically to each other on a substrate to form a three-component inductive magnetic field sensor, its volume is 255 mm×255 mm×255 mm, and the mass is 10 kg. The inclination and azimuth angle are measured by installing the directional device, and the magnetic field data correction is carried out to realize the validity of the measurement data under any attitude. Effective operation is carried out in shallow water by installing a waterproof hood. Field experiments show that the three-component magnetic field sensor can be arranged on the ground, and can be arranged in the shallow water to carry out AMT work, which greatly improves the field construction efficiency and has a broad application prospects.

In tight oil and gas reservoirs,cracks are important seepage channels and reservoir spaces for hydrocarbon migration.The development of the crack directly controls the reservoir performance.In order to evaluate the crack development by using the shear and Stoneley wave attenuation information,the authors used the three-dimensional variable grid time domain finite difference method to study the influence of crack widths and angles on shear and Stoneley wave attenuation in the wellbore environment.The results show that,as the crack width increases,the transmitted Shear wave and the Stoneley wave undergo energy decay.When the crack is tilted,the transmission Stoneley wave is insensitive to the crack dip.As the dip angle becomes larger,the attenuation does not change much.However,the transmitted shear wave is more sensitive to the crack dip.When the crack dip angle is 0°,the transmitted shear wave attenuation amplitude is the largest.As the dip angle of the crack becomes larger,the attenuation of the transmitted shear wave becomes significantly smaller.When the crack dip angle is greater than 25°,the attenuation amplitude of the transmitted shear wave becomes smaller and smaller as the angle increases.In addition,the numerical simulation of the shear wave attenuation curve is compared with the shear wave attenuation curve in the physical experiment, and the two are in good agreement.This study has a certain theoretical guidance for improving the acoustic logging evaluation method of fractured reservoirs.

The thickness distribution of coal seams results from the combined control of various geological factors, and the control factors of coal are different in different regions. Previous studies have focused on qualitative comparative analysis, and hence it is very difficult for them to identify accurately the control factors and their distribution. In this study, according to the multi-fractal characteristics and the generalized self-similarity principle of the coal seam thickness spatial distribution, the authors transformed coal seam thickness into feature space and performed singular value decomposition. Based on the fractal law of energy measure and energy spectral density,the authors used the least squares method to fit singular value decomposition figure into multipul lines, determined different inflection points, selected the singular value and the corresponding feature subspace in the first three sections for reconstruction, compared anomalies after reconstruction with various variables that affect the thickness of coal seams, extracted various implicit geological factors for coal control, and thus realized the quantitative analysis of controlling factors of coal seam thickness. The authors analyzed the No. 8 main coal seam in Panji coal mine (peripheral) of Huainan as a study case, detected the fact that the main control factors for the thickness of coal seam in this area are ancient terrain, same sedimentary structure and hydrodynamic conditions in ancient geography, and compared the results with the control factors obtained by the corresponding analysis. The results show the effectiveness of this method in quantitative analysis.

The correlation imaging method is mainly used to solve the location of anomalous source space, but its imaging results are not ideal, and there is divergence in the longitudinal direction. Due to the confirmatory effect of forward modeling on imaging, this paper designs a simple model and multiple anomaly source overlay models. The traditional imaging methods based on Pearson similarity algorithm and cosine similarity algorithm are studied. It is pointed out that Pearson similarity is used to calculate gravity anomalies in traditional correlation imaging. The phenomenon of false anomalies occurs, the related imaging based on Tanimoto similarity is proposed, and the kernel function is improved for the algorithm. The research shows that the method proposed in this paper has an improved vertical and horizontal resolution of the source compared with the traditional correlation imaging method, and the abnormal source form outlines the accurate features, which provides powerful information for the interpretation of gravity data.

Based on the current evaluation standards of soil environmental quality and food safety, the authors used the single factor index method, Nemero composite index method and Hakanson potential ecological hazard index method to carry out soil heavy metal pollution and potential ecological risk assessment so as to find out the environmental risk level and spatial distribution characteristics of soil heavy metal pollution in the study area. The results of Nemero composite index evaluation indicate that high pollution occurs in the study area, and the proportion of slight pollution , moderate pollution and high pollution is respectively 39.03%, 16.62% and 28.57%. However, the potential ecological risk of Cu, Hg, As, Ni, Pb, Cr, Zn is low in soil in eight heavy metals, while the level of risk of Cd is higher, and the proportion of the samples with low, medium, slight, high, seriously potential risk is 17.71%, 17.71%, 22.77%, 12.31% and 8.00%, with the average of potential ecological harm index ( E_r^i )being 118.24. The sites of high and higher potential ecological hazard of Cd in the soil are mainly located in the Lower Permian stratigraphic unit. Meanwhile, the heavy metal evaluation of 45 corn seeds shows that only one corn seed has excessive Cd content, and there is no obvious correlation between the content of Cd in corn seeds and the corresponding crop root soil. The high content of Cd seems mainly affected by geological background, but has no influence on corn seeds in the study area,and the risk of the absorption and enrichment of Cd by crops is higher with the increase of the soluble Cd content in a highly acidic soil environment.

Selenium (Se) in plants is mainly derived from soil, and plants can be used not only to alleviate the problem of selenium deficiency, but also to manage environmental selenium toxicity. On the basic of 6 917 co-samples of soil and rice, 1 489 co-samples of soil and wheat, and 1 816 co-samples of soil and corn seed, the Selenium concentration in selenium-enriched soil was 0.22×10 ^-6≤w(Se)<3.0×10 ^-6 for rice producing areas, 0.31×10 ^-6≤w(Se)<1.0×10 ^-6 for wheat planting area, and 0.94×10 ^-6≤w(Se)<4.91×10 ^-6 for corn planting area. It is of great significance to the scientific utilization of selenium-enriched soil resources and the development of selenium-enriched agricultural products.

Taking the selenium-enriched soil of Jizhou in Tianjin as the research object, the causes and influential factors of selenium-enriched soil were analyzed. The results showed that the average content of selenium in soil of the study area was 0.37×10 ^-6, which was higher than the national average level of selenium (0.29×10 ^-6), and the proportion of selenium-enriched soil (>0.4×10 ^-6) was 31.7%. The soil selenium content in the study area was significantly affected by soil type, land use pattern and organic matter content, and it was significantly positively correlated with heavy metals such as cadmium, lead, arsenic and zinc in soil. The content of selenium in dry deposition of atmosphere in the study area is 2.77×10 ^-6, which is 12 times of the local background value, while the content of selenium in organic fertilizer is 0.88×10 ^-6, which is 3.8 times of the background value. The amounts of selenium in dry deposition and organic fertilizer were 0.53 mg/(m ²·a) and 2.2 mg/m ², respectively, indicating parent material, dry deposition and organic fertilizer were important sources of soil selenium in soil.

Through investigation and sampling Carya cathayensis kernels and soil of plantations, the heavy metals, Se, organic matter and other indicators in soil were analyzed, and the pollution degrees of heavy metals in soil were evaluated with risk screening values as the criteria. The content of heavy metals, Se, Ge and other trace components in kernels was analyzed, and the relationship between soil and kernels was discussed. The results show that the average values of Cu, Pb, Zn, Ni, Cr, Cd, As, Hg and Se in the soil of Carya cathayensis plantations are higher than those of the average soil of China, especially Cd is 5.6 times that of the average soil of China. Local soil Cd and As in the study area have reached the pollution level while the ecological risk of other heavy metals is slight. Carya cathayensis kernels have low Cd, Hg, Pb, As and other heavy metals content, no excessive heavy metal elements, low ecological risk, and high zinc content, with the potential to develop zinc-rich health food. Carya cathayensis has a significant difference in the absorption capacity of different heavy metals. The absorption capacity of zinc and copper is much greater than that of Cd, Cr and Hg.

Natural source surface wave technology which is a traditional geophysical exploration method is widely used in shallow geological survey and engineering site evaluation.In this paper,the experimental application of natural source surface wave technology in urban geological survey of Urumqi is introduced.By measuring the velocity structure of surface wave at a single point,the strata and structures in the area are delineated,and a number of engineering parameters for site evaluation are obtained.Through application and research,it is verified that natural source surface wave technology can be effectively used in urban areas characterized by dense population,complex environment and serious disturbance.The application process of natural source surface wave technology in urban geological survey is established.The results have guiding significance for the further exploration of urban underground space resources.

In order to understand the influence of different propelling distances on water inrush from the working face floor during the mining of steep inclined coal seam, the authors detected the water-bearing strength and water-bearing position of the working face floor at 31515 of a coal mine in Shandong Province by TEM. Then, the fem difference software FLAC ^3D was used to simulate the formation and evolution of water inrush channels on the bottom of steep inclined coal seam face in the confined aquifer when different propulsion lengths were simulated. And the change of the pressure water conduction height and seepage flow vector of the bottom plate with the advance of the working face was investigated. The results show that the working face stoping makes the floor form the plastic failure zone, and under the action of the pore pressure of the water in the confined aquifer of the floor, the uplift zone of confined water and the mining failure zone of the floor are conductive, thus the risk of water inrush from the coal seam floor is easy to occur.

In order to study the detection effect of opposing coils transient electromagnetics method on the goaf of a gypsum mine in Linli, the author arranged two lines in the mining area for the experiment of opposing coils transient electromagnetics method. A line was arranged in the area without goaf., and the other line was located above the known goaf. By comparing the results of the two lines, it can be seen that, in the inversion resistivity profile of the opposing coils transient electromagnetics method, the resistivity isoline without goaf is gentle and layered, which basically reflects the layered characteristics of the strata. The resistivity isoline with goaf is obviously concave, and the resistivity value is low, which is a low resistivity abnormal zone. It can be seen that the opposing coils transient electromagnetics method is effective in detecting the goaf of a gypsum mine in Linli, and can determine the basic location of the goaf. It can be used to detect goaf of gypsum ore in this gypsum mining area or similar gypsum mining areas.