Langshan, a monoclinic mountain, which started to uplift since Oligocene, bounds the northwest margin of the Hetao Basin. The continuous activity of the active normal Langshan range- front fault forms the typical basi...Langshan, a monoclinic mountain, which started to uplift since Oligocene, bounds the northwest margin of the Hetao Basin. The continuous activity of the active normal Langshan range- front fault forms the typical basin-and-range landform in Langshan area and controls the landform evolution of Langshan. Langshan is an ideal place to study relationship between quantitative geomor- phological index and active deformation. According to study on knickpoints, fitting on longitudinal channel profiles and steepness index, we demonstrate that the main controlling factors on distribution of normalized steepness index of channels are not climate （precipitation）, lithology, sediment flux, but tectonic factor, or the activity of Langshan range-front fault. The short channels in southeast flank, whose lengths are shorter than 16 km, may be still in the non-steady status. If not considering these short channels, the distribution of normalized steepness index along the Langshan range-front fault appears like M-shape pattern, while the normalized steepness index in the middle section is higher than those at both ends. This pattern is well consistent with geometrical segmentation model of the Langshan range-front fault. Combining previous active tectonic research on Langshan range-front fault, which demonstrates the Langshan range-front fault has been in the stage of linkup, we reasonably infer the Langshan range-front fault now is the result of linkup of both fault which continuously bilaterally ex- tended independently. Our tectonic geomorphological study also supports the conclusion that the Langshan range-front fault has been in the stage of linkup. The formation of several knickpoints due to tectonic factor may have been caused by slip-rate variation because of linkup of both independent faults. Based on cognition above, we also proposed the geological and geomorphological evolutionary model of the Langshan range-front fault since Oligocene.展开更多
Based on new data from cores,drilling and logging,combined with extensive rock and mineral testing analysis,a systematic analysis is conducted on the characteristics,diagenesis types,genesis and controlling factors of...Based on new data from cores,drilling and logging,combined with extensive rock and mineral testing analysis,a systematic analysis is conducted on the characteristics,diagenesis types,genesis and controlling factors of deep to ultra-deep abnormally high porosity clastic rock reservoirs in the Oligocene Linhe Formation in the Hetao Basin.The reservoir space of the deep to ultra-deep clastic rock reservoirs in the Linhe Formation is mainly primary pores,and the coupling of three favorable diagenetic elements,namely the rock fabric with strong compaction resistance,weak thermal compaction diagenetic dynamic field,and diagenetic environment with weak fluid compaction-weak cementation,is conducive to the preservation of primary pores.The Linhe Formation clastic rocks have a superior preexisting material composition,with an average total content of 90%for quartz,feldspar,and rigid rock fragments,and strong resistance to compaction.The geothermal gradient in Linhe Depression in the range of(2.0–2.6)°C/100 m is low,and together with the burial history of long-term shallow burial and late rapid deep burial,it forms a weak thermal compaction diagenetic dynamic field environment.The diagenetic environment of the saline lake basin is characterized by weak fluid compaction.At the same time,the paleosalinity has zoning characteristics,and weak cementation in low salinity areas is conducive to the preservation of primary pores.The hydrodynamic conditions of sedimentation,salinity differentiation of ancient water in saline lake basins,and sand body thickness jointly control the distribution of high-quality reservoirs in the Linhe Formation.展开更多
Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation metho...Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation methods on carbon dioxide(CO_(2))exchange and crop growth in this region.The experimental site was divided into drip and flood irrigation zones.The irrigation schedules of this study aligned with the local commonly used irrigation schedule.We employed a developed chamber system to measure the diurnal CO_(2)exchange of maize plants during various growth stages under both drip and flood irrigation methods.From May to September in 2020 and 2021,two sets of repeated experiments were conducted.In each experiment,a total of nine measurements of CO_(2)exchange were performed to obtain carbon exchange data at different growth stages of maize crop.During each CO_(2)exchange measurement event,CO_(2)flux data were collected every two hours over a day-long period to capture the diurnal variations in CO_(2)exchange.During each CO_(2)exchange measurement event,the biological parameters(aboveground biomass and crop growth rate)of maize and environmental parameters(including air humidity,air temperature,precipitation,soil water content,and photosynthetically active radiation)were measured.The results indicated a V-shaped trend in net ecosystem CO_(2)exchange in daytime,reducing slowly at night,while the net assimilation rate(net primary productivity)exhibited a contrasting trend.Notably,compared with flood irrigation,drip irrigation demonstrated significantly higher average daily soil CO_(2)emission and greater average daily CO_(2)absorption by maize plants.Consequently,within the maize ecosystem,drip irrigation appeared more conducive to absorbing atmospheric CO_(2).Furthermore,drip irrigation demonstrated a faster crop growth rate and increased aboveground biomass compared with flood irrigation.A strong linear relationship existed between leaf area index and light utilization efficiency,irrespective of the irrigation m展开更多
The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous ...The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous is still controversial.Integrating the apatite fission track(AFT)data in both this study and previous works,a three-stage exhumation history from Cretaceous to Neogene of the DQS is proposed.(1)The first stage is composed of the early exhumation during Early Cretaceous driven by the collision between the North China and Siberia cratons(ca.148-132 Ma)and the far-field effect of the subduction of the Pacific Plate(ca.132-114 Ma).(2)Due to the subsidence of the Hetao Basin and the subsequent compensation between the DQS and the Hetao Basin,the DQS experienced the second rapid exhumation from Early Eocene to Early Oligocene(ca.54-29 Ma).(3)Since the Late Miocene(ca.13.5 Ma),the third rapid cooling and exhumation of the DQS occurred due to the far-field effect of the uplift of the Tibetan Plateau and the subduction of the Pacific Plate.展开更多
Salinity is one of the major abiotic factors affecting the growth and productivity of crops in Hetao Irrigation District, China. In this study, the salinity tolerances of three local crops, wheat （Triticum aestinum L...Salinity is one of the major abiotic factors affecting the growth and productivity of crops in Hetao Irrigation District, China. In this study, the salinity tolerances of three local crops, wheat （Triticum aestinum L.）, maize （Zea mays L.） and sunflower （Helianthus annuus L.）, growing in 76 farm fields are evaluated with modified discount function. Salinity ecological zones appropriate for these local crops are characterized and a case study is presented for crop salinity ecological zoning. The results show that the yield reductions of wheat, maize and sunflower when grown in saline soils are attributed primarily to a reduction in spikelet number, 1 000-grain weight and seed number per head, respectively. Sunflower is the most tolerant crop among the three which had a salinity tolerance index （ST-index） of 12.24, followed by spring maize and spring wheat with ST-Indices of 9.00 and 7.43, respectively. According to the crop salinity tolerance results, the arable land in the Heping Village of this district was subdivided into four salinity ecological zones： the most suitable, suitable, sub-suitable and unsuitable zones. The area proportion of the most suitable zone for wheat, maize and sunflower within the Heping Village was 27.5, 46.5 and 77.5%, respectively. Most of the most suitable zone occurred in the western part of the village. The results of this study provide the scientific basis for optimizing the local major crop distribution and improving cultural practices management in Hetao Irrigation District.展开更多
[Objectives]To evaluate the impacts of the elemental sulfur(S 0)and micro-algae(MA)co-fertilization on saline-alkaline soil of sunflower field in the Hetao Irrigation District(HID).[Methods]The greenhouse pot experime...[Objectives]To evaluate the impacts of the elemental sulfur(S 0)and micro-algae(MA)co-fertilization on saline-alkaline soil of sunflower field in the Hetao Irrigation District(HID).[Methods]The greenhouse pot experiment was conducted with four treatments:control(CK),single S 0 fertilization(S),single MA fertilization(A),and S 0 and MA co-fertilization(SA)for comparing the selected soil properties and sunflower plant heights and weights in different treatments.[Results]The results showed that the mean soil organic matter(SOM)under the SA(25.08 g/kg)was significantly higher than that for the CK(20.59 g/kg),S(22.47 g/kg),and A(22.95 g/kg).The mean pH under the SA(7.75)was significantly lower than that for the CK(8.14),S(7.82),and A(7.96).The mean soil exchangeable Na+concentration under the SA was significantly lower than that for the S.The mean soil electrical conductivity(EC)under the SA was 9.76%lower than that for the S.The means of Cl-(1.22 g/kg)and SO 2-4(1.90 g/kg)in soil under the SA were lower than that for the S(1.30,2.06 g/kg)and A(1.31,1.97 g/kg),respectively.For plant height 3 at the late stage of plant growth,the mean plant height 3 under the SA(89.00 cm)was higher than that of the CK(69.60 cm)and A(74.33 cm).The total weights of the fresh sunflower heads,fresh stems,and dry seeds under the SA were higher than that for the CK,S,and A.[Conclusions]In conclusion,the S 0 and MA co-fertilization had positive effects on improving saline-alkaline soils,the soil under the S 0 and MA co-fertilization could be better conditions for promoting sunflower growth than that for the S,Z,and CK,and thereby the S 0 and MA co-fertilization could be a new idea to improve saline-alkaline soil in the cold and arid regions.展开更多
Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydro...Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.展开更多
To investigate geochemical and mineralogical features of sediments from aquifers containing high levels of dissolved arsenic（As） in western Hetao Basin, Inner Mongolia, sediment samples were collected for XRD（X-ray...To investigate geochemical and mineralogical features of sediments from aquifers containing high levels of dissolved arsenic（As） in western Hetao Basin, Inner Mongolia, sediment samples were collected for XRD（X-ray diffraction）, amorphous Fe/Mn oxides, and humic/fulvic acid analyses, in addition to As determination. In the study area, the total As contents in the sediments were in the range 5.3–28.8 mg/kg; while that associated with humic substances in the range 4–9 mg/kg, accounting for 26%–47% of the total As. The results of XRD analysis suggest that clay and silt contain certain small amounts of iron oxides minerals, such as ferrihydrite, hematite and goethite, whereas have higher As and Fe_2O_3 contents. Up to one third of As in the sediments could be extracted by ammonium oxalate, and high As contents were generally found in organic-rich clay or silty clay samples with high FA/HA ratio. As is strongly associated with humic substances and Fe oxyhydroxides, which may be the major sink and source of As in the aquifer sediments.展开更多
This paper analyzes the impacts of physical background and human activities on secondary soil salinization in arid Hetao Plain,overviews the adopted amelioration strategies,and suggests the corresponding strategies de...This paper analyzes the impacts of physical background and human activities on secondary soil salinization in arid Hetao Plain,overviews the adopted amelioration strategies,and suggests the corresponding strategies dealing with water shortage in the Yellow River.展开更多
Focusing on the b-value as the research target and under the theoretical framework that the b-value is determined by stress state and medium properties, the variation characteristics of the b-value in the Hetao seismi...Focusing on the b-value as the research target and under the theoretical framework that the b-value is determined by stress state and medium properties, the variation characteristics of the b-value in the Hetao seismic belt are analyzed. Earthquakes with ML≥1. 5,which have occurred in the Hetao seismic belt since 1970 are selected to conduct the quantitative detection of the non-uniform temporal change of Mcusing the EMR method. Based on the actual situation of seismic activity,the lower limit magnitude is set as ML2. 0 to calculate the b-value. The temporal variation of the b-value is calculated and scanned using the least square method. The results show that there is a good corresponding relationship between the temporal variation of the b-value,strong earthquake activity,network distribution and aftershock deletion. We also calculate and scan the spatial variation of the b-value by using maximum likelihood. The results show that the spatial difference is possibly caused by stress state and crustal medium properties. The tectonic dependence of the b-value is obvious. In addition,the sufficient earthquakes samples in each magnitude interval are still a key step to improve the calculation accuracy of the b-value.展开更多
基金funded jointly by the National Natural Science Foundation of China (Nos. 41402187, 41372220, 41590861, 41661134011)
文摘Langshan, a monoclinic mountain, which started to uplift since Oligocene, bounds the northwest margin of the Hetao Basin. The continuous activity of the active normal Langshan range- front fault forms the typical basin-and-range landform in Langshan area and controls the landform evolution of Langshan. Langshan is an ideal place to study relationship between quantitative geomor- phological index and active deformation. According to study on knickpoints, fitting on longitudinal channel profiles and steepness index, we demonstrate that the main controlling factors on distribution of normalized steepness index of channels are not climate （precipitation）, lithology, sediment flux, but tectonic factor, or the activity of Langshan range-front fault. The short channels in southeast flank, whose lengths are shorter than 16 km, may be still in the non-steady status. If not considering these short channels, the distribution of normalized steepness index along the Langshan range-front fault appears like M-shape pattern, while the normalized steepness index in the middle section is higher than those at both ends. This pattern is well consistent with geometrical segmentation model of the Langshan range-front fault. Combining previous active tectonic research on Langshan range-front fault, which demonstrates the Langshan range-front fault has been in the stage of linkup, we reasonably infer the Langshan range-front fault now is the result of linkup of both fault which continuously bilaterally ex- tended independently. Our tectonic geomorphological study also supports the conclusion that the Langshan range-front fault has been in the stage of linkup. The formation of several knickpoints due to tectonic factor may have been caused by slip-rate variation because of linkup of both independent faults. Based on cognition above, we also proposed the geological and geomorphological evolutionary model of the Langshan range-front fault since Oligocene.
基金Supported by the CNPC Science and Technology Project(2023ZZ022023ZZ14-01).
文摘Based on new data from cores,drilling and logging,combined with extensive rock and mineral testing analysis,a systematic analysis is conducted on the characteristics,diagenesis types,genesis and controlling factors of deep to ultra-deep abnormally high porosity clastic rock reservoirs in the Oligocene Linhe Formation in the Hetao Basin.The reservoir space of the deep to ultra-deep clastic rock reservoirs in the Linhe Formation is mainly primary pores,and the coupling of three favorable diagenetic elements,namely the rock fabric with strong compaction resistance,weak thermal compaction diagenetic dynamic field,and diagenetic environment with weak fluid compaction-weak cementation,is conducive to the preservation of primary pores.The Linhe Formation clastic rocks have a superior preexisting material composition,with an average total content of 90%for quartz,feldspar,and rigid rock fragments,and strong resistance to compaction.The geothermal gradient in Linhe Depression in the range of(2.0–2.6)°C/100 m is low,and together with the burial history of long-term shallow burial and late rapid deep burial,it forms a weak thermal compaction diagenetic dynamic field environment.The diagenetic environment of the saline lake basin is characterized by weak fluid compaction.At the same time,the paleosalinity has zoning characteristics,and weak cementation in low salinity areas is conducive to the preservation of primary pores.The hydrodynamic conditions of sedimentation,salinity differentiation of ancient water in saline lake basins,and sand body thickness jointly control the distribution of high-quality reservoirs in the Linhe Formation.
基金supported by the Shandong Province Natural Science Foundation Youth Branch(ZR2023QC157)the National Natural Science Foundation of China(51979233)+1 种基金the Key Research and Development Project of Shaanxi Province(2022KW-47,2022NY-220)the Heze University Doctoral Research Fund(XY21BS24,XY22BS17).
文摘Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation methods on carbon dioxide(CO_(2))exchange and crop growth in this region.The experimental site was divided into drip and flood irrigation zones.The irrigation schedules of this study aligned with the local commonly used irrigation schedule.We employed a developed chamber system to measure the diurnal CO_(2)exchange of maize plants during various growth stages under both drip and flood irrigation methods.From May to September in 2020 and 2021,two sets of repeated experiments were conducted.In each experiment,a total of nine measurements of CO_(2)exchange were performed to obtain carbon exchange data at different growth stages of maize crop.During each CO_(2)exchange measurement event,CO_(2)flux data were collected every two hours over a day-long period to capture the diurnal variations in CO_(2)exchange.During each CO_(2)exchange measurement event,the biological parameters(aboveground biomass and crop growth rate)of maize and environmental parameters(including air humidity,air temperature,precipitation,soil water content,and photosynthetically active radiation)were measured.The results indicated a V-shaped trend in net ecosystem CO_(2)exchange in daytime,reducing slowly at night,while the net assimilation rate(net primary productivity)exhibited a contrasting trend.Notably,compared with flood irrigation,drip irrigation demonstrated significantly higher average daily soil CO_(2)emission and greater average daily CO_(2)absorption by maize plants.Consequently,within the maize ecosystem,drip irrigation appeared more conducive to absorbing atmospheric CO_(2).Furthermore,drip irrigation demonstrated a faster crop growth rate and increased aboveground biomass compared with flood irrigation.A strong linear relationship existed between leaf area index and light utilization efficiency,irrespective of the irrigation m
基金supported by the Major National Science and Technology Projects of China(No.2016ZX05034001-006)the National Natural Science Foundation of China(Nos.42072132,41202104,and 41572131)the China Geological Survey Projects(Nos.DD20190103 and DD20190711)。
文摘The Daqing Shan(DQS)located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton.However,the cooling and exhumation history since the Cretaceous is still controversial.Integrating the apatite fission track(AFT)data in both this study and previous works,a three-stage exhumation history from Cretaceous to Neogene of the DQS is proposed.(1)The first stage is composed of the early exhumation during Early Cretaceous driven by the collision between the North China and Siberia cratons(ca.148-132 Ma)and the far-field effect of the subduction of the Pacific Plate(ca.132-114 Ma).(2)Due to the subsidence of the Hetao Basin and the subsequent compensation between the DQS and the Hetao Basin,the DQS experienced the second rapid exhumation from Early Eocene to Early Oligocene(ca.54-29 Ma).(3)Since the Late Miocene(ca.13.5 Ma),the third rapid cooling and exhumation of the DQS occurred due to the far-field effect of the uplift of the Tibetan Plateau and the subduction of the Pacific Plate.
基金supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (2009030012-3)
文摘Salinity is one of the major abiotic factors affecting the growth and productivity of crops in Hetao Irrigation District, China. In this study, the salinity tolerances of three local crops, wheat （Triticum aestinum L.）, maize （Zea mays L.） and sunflower （Helianthus annuus L.）, growing in 76 farm fields are evaluated with modified discount function. Salinity ecological zones appropriate for these local crops are characterized and a case study is presented for crop salinity ecological zoning. The results show that the yield reductions of wheat, maize and sunflower when grown in saline soils are attributed primarily to a reduction in spikelet number, 1 000-grain weight and seed number per head, respectively. Sunflower is the most tolerant crop among the three which had a salinity tolerance index （ST-index） of 12.24, followed by spring maize and spring wheat with ST-Indices of 9.00 and 7.43, respectively. According to the crop salinity tolerance results, the arable land in the Heping Village of this district was subdivided into four salinity ecological zones： the most suitable, suitable, sub-suitable and unsuitable zones. The area proportion of the most suitable zone for wheat, maize and sunflower within the Heping Village was 27.5, 46.5 and 77.5%, respectively. Most of the most suitable zone occurred in the western part of the village. The results of this study provide the scientific basis for optimizing the local major crop distribution and improving cultural practices management in Hetao Irrigation District.
基金Supported by“Bayannur Ecological Governance and Green Development Academician Expert Workstation Construction Project of Hetao College”Provided by the Inner Mongolia Autonomous Region Science and Technology Department“Investigation of Agricultural Soil Carbon Dioxide Emission and Soil Quality Improvement in the Hetao Irrigation District”Provided by the Inner Mongolia Science and Technology Program.
文摘[Objectives]To evaluate the impacts of the elemental sulfur(S 0)and micro-algae(MA)co-fertilization on saline-alkaline soil of sunflower field in the Hetao Irrigation District(HID).[Methods]The greenhouse pot experiment was conducted with four treatments:control(CK),single S 0 fertilization(S),single MA fertilization(A),and S 0 and MA co-fertilization(SA)for comparing the selected soil properties and sunflower plant heights and weights in different treatments.[Results]The results showed that the mean soil organic matter(SOM)under the SA(25.08 g/kg)was significantly higher than that for the CK(20.59 g/kg),S(22.47 g/kg),and A(22.95 g/kg).The mean pH under the SA(7.75)was significantly lower than that for the CK(8.14),S(7.82),and A(7.96).The mean soil exchangeable Na+concentration under the SA was significantly lower than that for the S.The mean soil electrical conductivity(EC)under the SA was 9.76%lower than that for the S.The means of Cl-(1.22 g/kg)and SO 2-4(1.90 g/kg)in soil under the SA were lower than that for the S(1.30,2.06 g/kg)and A(1.31,1.97 g/kg),respectively.For plant height 3 at the late stage of plant growth,the mean plant height 3 under the SA(89.00 cm)was higher than that of the CK(69.60 cm)and A(74.33 cm).The total weights of the fresh sunflower heads,fresh stems,and dry seeds under the SA were higher than that for the CK,S,and A.[Conclusions]In conclusion,the S 0 and MA co-fertilization had positive effects on improving saline-alkaline soils,the soil under the S 0 and MA co-fertilization could be better conditions for promoting sunflower growth than that for the S,Z,and CK,and thereby the S 0 and MA co-fertilization could be a new idea to improve saline-alkaline soil in the cold and arid regions.
基金Supported by the PetroChina Key Science and Technology (2021DJ0703)。
文摘Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.
基金financially supported by the National Natural Science Foundation of China(No.41572226)
文摘To investigate geochemical and mineralogical features of sediments from aquifers containing high levels of dissolved arsenic（As） in western Hetao Basin, Inner Mongolia, sediment samples were collected for XRD（X-ray diffraction）, amorphous Fe/Mn oxides, and humic/fulvic acid analyses, in addition to As determination. In the study area, the total As contents in the sediments were in the range 5.3–28.8 mg/kg; while that associated with humic substances in the range 4–9 mg/kg, accounting for 26%–47% of the total As. The results of XRD analysis suggest that clay and silt contain certain small amounts of iron oxides minerals, such as ferrihydrite, hematite and goethite, whereas have higher As and Fe_2O_3 contents. Up to one third of As in the sediments could be extracted by ammonium oxalate, and high As contents were generally found in organic-rich clay or silty clay samples with high FA/HA ratio. As is strongly associated with humic substances and Fe oxyhydroxides, which may be the major sink and source of As in the aquifer sediments.
基金funded in part by National Natural Science Fund (No. 30671722)
文摘This paper analyzes the impacts of physical background and human activities on secondary soil salinization in arid Hetao Plain,overviews the adopted amelioration strategies,and suggests the corresponding strategies dealing with water shortage in the Yellow River.
基金sponsored by the Spark Program of Earthquake Sciences of China Earthquake Administration(XH15010 Y)
文摘Focusing on the b-value as the research target and under the theoretical framework that the b-value is determined by stress state and medium properties, the variation characteristics of the b-value in the Hetao seismic belt are analyzed. Earthquakes with ML≥1. 5,which have occurred in the Hetao seismic belt since 1970 are selected to conduct the quantitative detection of the non-uniform temporal change of Mcusing the EMR method. Based on the actual situation of seismic activity,the lower limit magnitude is set as ML2. 0 to calculate the b-value. The temporal variation of the b-value is calculated and scanned using the least square method. The results show that there is a good corresponding relationship between the temporal variation of the b-value,strong earthquake activity,network distribution and aftershock deletion. We also calculate and scan the spatial variation of the b-value by using maximum likelihood. The results show that the spatial difference is possibly caused by stress state and crustal medium properties. The tectonic dependence of the b-value is obvious. In addition,the sufficient earthquakes samples in each magnitude interval are still a key step to improve the calculation accuracy of the b-value.
