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Loosening earth pressure above shallow trapdoor in unsaturated soil with different groundwater level

Frontiers of Structural and Civil Engineering 2024年第10期18卷 1626-1635页

作者： Yun ZHAO zhongfang yang Zhanglong CHEN Daosheng LING College of Civil Engineering and Architecture Henan University of TechnologyZhengzhou 450001China MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang UniversityHangzhou 310058China State Key Laboratory of Hydro-Science and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China

The consideration of unsaturated conditions is infrequently addressed in current Terzaghi’s soil arching research.A modified analytical method for calculation of unsaturated loosening earth pressure above shallow trapdoor is proposed in this *** assuming the existence of a vertical slip surface above the trapdoor,the stress state of the soil in the loosening area are delineated in the extended Mohr–Coulomb *** account for the non-uniform distribution of vertical stress at arbitrary points along the horizontal differential soil trip,a virtual rotation circle trajectory of major principal stress is ***,the average vertical stress acting on the soil trip is determined through integral *** into account the influence of matric suction on soil weight and apparent cohesion,the differential equation governing the soil trip is solved analytically for cases of uniform matric suction distribution and alternatively using the finite difference method for scenarios involving non-uniform matric suction *** proposed method’s validity is confirmed through comparison with published *** parameter analysis indicates that the loosening earth pressure initially decreases and subsequently increases with the increase of the soil *** the rise of groundwater level,the normalized effective loosening earth pressure shows a decreasing trend.

关键词： soil arching effect unsaturated soil trapdoor test loosening earth pressure groundwater level variation

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Climate and Soil Geochemistry Influence the Soil Organic Carbon Content in Drylands of the Songliao Plain,Northeast China

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Acta Geologica Sinica(English Edition) 2024年第5期98卷 1394-1403页

作者： LIU Kai DAI Huimin SONG Yunhong LIANG Shuai yang zhongfang School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Key Laboratory of Black Soil Evolution and Ecological Effect Ministry of Natural Resources/Liaoning ProvinceShenyang 110000China Shenyang Center of China Geological Survey Northeast Geological S&T Innovation Center of China Geological SurveyShenyang 110000China

The understanding of the spatial distribution of soil organic carbon(SOC)and its influencing factors is crucial for comprehending the global carbon ***,the impact of soil geochemical and climatic conditions on SOC remains limited,particularly in dryland farming *** this study,we aimed to enhance the understanding of the factors influencing the distribution of SOC in the drylands of the Songliao Plain,Northeast China.A dataset comprising 35,188 measured soil samples was used to map the SOC distribution in the *** linear regression(MLR)and random forest models(RFM)were employed to assess the importance of driving indicators for *** also carried out partial correlation and path analyses to further investigate the relationship between climate and *** SOC content in dryland soils of the Songliao Plain ranged from 0.05%to 11.63%,with a mean value of 1.47%±0.90%.There was a notable increasing trend in SOC content from the southwest to the northeast *** results of MLR and RFM revealed that temperature was the most critical factor,demonstrating a significant negative correlation with SOC ***,iron oxide was the most important soil geochemical indicator affecting SOC *** research further suggested that climate may exert an indirect influence on SOC concentrations through its effect on geochemical properties of *** insights highlight the importance of considering both the direct and indirect impact of climate in predicting the SOC under future climate change.

关键词： soil organic carbon climate change soil geochemistry Northeast China

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Alkylammonium cations treating and K-Ar dating of illite from mudstones

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Chinese Science Bulletin 2002年第19期47卷 1669-1672页

作者： yang zhongfang JI Junfeng CHE Chen ZHOU Fengying China University of Geosciences Beijing 100083China State Key Laboratory of Mineral Deposit Research Institute of Surfacial GeochemistryDepartment of Earth SciencesNanjing UniversityNanjing 210093China Deposit Institute of Chinese Academy of Geological Sciences Beijing 100037China

Two kinds of mudstones from the Tarim Basin and the Tuna Basin were treated with C8 and C18 alkylammonium cations. Both of them were dated by the K-Ar method. One kind of rock contains mainly diagenetic illite, and the other contains mixed layer illite/smectite (I/S). Sample separation and alkylamnionium cations treatment were performed first, and K-Ar dating followed. The result shows that fine-grained minerals have younger K-Ar ages and coarse-grained components have older ages. Plots of K-Ar age versus K2O (%) are linear, the range of diagenetic age can be estimated by extrapolation. The reaction results of the above samples are different after alkylamnionium cations treatments. The samples containing mainly illite show a decrease in K2O and an increase in age by 1-25 Ma, suggesting that preferential exchange of young diagenetic clay rather than detrital clay by alkylamnionium cations, therefore the age of diagenetic illite can be calculated directly by the % K2O and radiogenic 40Ar removed. For the

关键词： alkylammonium cations illite K/Ar date mudstone.

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Seasonal variations in the Sr-Nd isotopic compositions of suspended particulate matter in the lower Changjiang River:Provenance and erosion constraints

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Chinese Science Bulletin 2011年第22期56卷 2371-2378页

作者： MAO ChangPing CHEN Jun YUAN XuYin yang zhongfang JI JunFeng Institute of Surficial Geochemistry School of Earth Sciences and Engineering Nanjing University Nanjing 210093 China College of Environmental Science and Engineering Hohai University Nanjing 210098 China School of Earth Science and Resources China University ofGeosciences (Beijing) Beijing 100083 China

Suspended particulate matter samples were collected monthly for more than 2 years in Nanjing,China to examine seasonal changes in the Sr-Nd isotopic compositions of the lower Changjiang River(CR).The results indicate that the 87Sr/86Sr ratios of the samples ranges from 0.725352 to 0.738128,and the values ofεNd(0)ranges from-10.55 *** Sr-Nd isotopic compositions show distinct seasonal *** samples had lower 87Sr/86Sr ratios and higherε Nd(0)values during the flood season than the dry *** seasonal variations primarily reflect the controls of provenance rocks and erosion in different *** relative decrease in 87Sr/86Sr ratios and the increase inε Nd(0)values during the flood season may reflect an increasing in the mechanical erosion rate in the upper basin and the contribution of more sediment from the upper *** end member values of 87Sr/86Sr andε Nd(0)of the samples were 0.728254 and?11.26,respectively.

关键词：同位素组成悬浮颗粒物季节变化侵蚀率 Sr Nd 长江季节性变化

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Spatial analysis of land use change effect on soil organic carbon stocks in the eastern regions of China between 1980 and 2000

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Geoscience Frontiers 2017年第3期8卷 597-604页

作者： Xueqi Xia zhongfang yang Yuan Xue Xin Shao Tao Yu Qingye Hou School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China Chongqing Institute of Land Surveying and Planning Chongqing 404000 China

Spatial distributions of 0-20 cm soil carbon sources/sinks caused by land use changes from the year 1980 to 2000 in an area of 2.97 ~ 106 km2 in eastern China were investigated using a land use dataset from a recent soil geochemical survey. A map of soil carbon sourcesJsinks has been prepared based on a spatial analysis scheme with GIg. Spatial statistics showed that land use changes had caused 30.7 ＋ 13.64 Tg of surface soil organic carbon loss, which accounts for 0.33% of the total carbon storage of 9.22 Pg. The net effect of the carbon source was estimated to be ~ 71.49 Tg soil carbon decrease and ~ 40.80 Tg increase. Land use changes in Northeast China （NE） have the largest impact on soil organic carbon storage compared with other regions. Paddy fields, which were mainly transformed into dry farmland in NE, and constructed land in other regions, were the largest carbon sources among the land use types. Swamp land in NE was also another large soil carbon source when it was transformed into dry farmland or paddy fields. Dry farmland in the NE region formed the largest soil organic carbon sink, as some were trans- formed into paddy fields, forested land, and other land use types with high SOCD.

关键词： Land use change Soil organic carbon GIS Eastern China

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Ecological risk assessment of Cd and other heavy metals in soil-rice system in the karst areas with high geochemical background of Guangxi,China

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Science China Earth Sciences 2021年第7期64卷 1126-1139页

作者： Qiong yang zhongfang yang Qizuan ZHANG Xu LIU Xiaoxiong ZHUO Tiansheng WU Lei WANG Xueji WEI Junfeng JI School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Guangxi Bureau of Geology&Mineral Prospecting&Exploitation Nanning 530023China Guangxi Institute of Geological Survey Nanning 530023China Geology Team No.4 of Guangxi Zhuang Autonomic Region Nanning 530031China Guangxi Geophysical Investigation Institute Liuzhou 545005China Key Laboratory of Surficial Geochemistry Ministry of EducationSchool of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China

Karst areas are widely distributed in China,and the soil derived in these areas is enriched with trace elements and has the typical characteristics of high geochemical ***,soil ecological risk has gradually attracted extensive *** this study,1090 sets of rice grains and paired rhizosphere soils were collected as research objects from the outcropped karst areas of carbonate rocks in Guangxi,and the concentration characteristics and influencing factors of heavy metals,such as Cd and As,in rice grains and the corresponding soils were *** to the Chinese Soil Environmental Quality Standard(GB 15618-2018),the proportion of karstic soil samples in Guangxi with heavy metal(As,Cd,Cr,Cu,Hg,Ni,Pb and Zn)concentrations that exceed the standard risk screening values was generally greater than that of surface soils in China or non-karstic soils in ***,Cd and As were the most prominently enriched heavy metals in *** to the Chinese Food Safety Standard(GB 2762-2017),Pb in rice grains from the studied area did not exceed the standard;the exceedance rates of Cr,Hg,and inorganic As were only about 1%;and the exceedance rate of Cd was 12.5%.Soil Cd concentration increased gradually whereas the concentration and exceedance rate of Cd in rice grains decreased gradually with the increase of soil ***,the exceedance rate of Cd in rice grains was only 4%when soil pH>*** results indicated that the risk screening values of Cd element in the Chinese Soil Environmental Quality Standard are not satisfactorily applicable to the ecological risk assessment of Cd in karstic ***,the recommended threshold values for the safe utilization and risk control of Cd in karstic soils was proposed so as to provide a basis for soil environmental quality hierarchization,pollution risk control and land safety zoning of agricultural land in karst areas in China.

关键词： Heavy metals Soil Rice grain Ecological risk assessment Karst area in Guangxi High geochemical background

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Solid-solution partitioning of arsenic(As) in the paddy soil profiles in Chengdu Plain,Southwest China

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Geoscience Frontiers 2012年第6期3卷 901-909页

作者： Xiaoyan yang Qingye Hou zhongfang yang Xin Zhang Yijun Hou School of Earth Science and Resources China University of Geosciences(Beijing)Beijing 100083China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China Information Center Ministry of Land and Resources of the People's Republic of ChinaBeijing 100033China

To predict the long-term behavior of arsenic （As） in soil profiles, the solid-solution partitioning of As was studied in four paddy soil profiles obtained from agricultural areas in Chengdu Plain, Southwest China. Paddy soil profile samples were collected and soil solution samples were extracted. Total As contents in soil solution and soil solid were analyzed, along with the soil solid phase properties. The As in soil solu- tion was significantly higher in the upper layer （0--20 cm） and had a definite tendency to decrease towards 40 cm regardless of the sampling locations. When the concentration of arsenic in soil solution decreased, its content in solid phase increased. Field-based partition coefficient （Kd） for As was determined by calculating the ratio of the amount of As in the soil solid phase to the As concentration in the soil solution. Kj values varied widely in vertical samples and correlated well with soil pH, total organic carbon （TOC） and total As. The results of this study would be useful for evaluating the accumulation trends of hrsenic in soil profiles and in improving the management of the agricultural soils.

关键词： Soil profiles Arsenic (As) Soil solution Partition coefficient (Kd)Geochemistry

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Temporal variation of soil carbon stock and its controlling factors over the last two decades on the southern Song-nen Plain,Heilongjiang Province

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Geoscience Frontiers 2010年第1期1卷 125-132页

作者： Xueqi Xia zhongfang yang Yan Liao Yujun Cui Yansheng Li School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China Heilongjiang Institute of Geological Survey Harbin 150036 China

Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.

关键词： The southern Song-nen Plain in Heilongjiang Province Soil carbon pool Spatial and temporal variation Carbon cycle

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A study of soil organic carbon distribution and storage in the Northeast Plain of China

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Geoscience Frontiers 2011年第2期2卷 115-123页

作者： Xiaohuan Xi zhongfang yang Yujun Cui Shumei Sun Chengguang Yu Min Li China Geological Survey Beijing China100037 School of the Earth Sciences and Resources China University of Geosciences Beijing 100083 China Heilongjiang Institute of Geological Survey Harbin 150036 China Jilin Institute of Geological Survey Changchun 130061 China Liaoning Institute of Geological Survey Shenyang 110032 China

Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）. The results indicated that the soil organic carbon （SOC） storage in topsoil （0-0.2 m）, subsoil （0-1 m） and deep soil （0-1.8 m） was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km^2, 12,904.7 t/km^2 and 16,157.5 t/km^2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain （Liaoning）, to the middle （Jilin） and the northern Plain （Heilongjiang） -- particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/kin2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984--1986 （SNSS）, the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt （29.4%）, with an average annual decline of 16.0 Mt （1.73%） over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km^2, 1646.4 t/kin2 and 1300.2 t/km^2, respectively, with an average value of 1389.0 t/km^2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land-use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.

关键词： Northeast Plain Multi-purpose RegionalGeochemical Survey Second National SoilSurvey SOC storage Distributioncharacteristics

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An effective strategy to establish a male sterility mutant mini-library by CRISPR/Cas9-mediated knockout of anther-specific genes in rice

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Journal of Genetics and Genomics 2019年第5期46卷 273-275页

作者： Kun Ma Jingluan Han Yu Hao zhongfang yang Junyu Chen Yao-Guang Liu Qinlong Zhu Letian Chen State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources South China Agricultural UniversityGuangzhou510642China Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms South China Agricultural UniversityGuangzhou510642China Key Laboratory of Plant Functional Genomics and Biotechnology of Guangdong Provincial Higher Education Institutions South China Agricultural UniversityGuangzhou510642China College of Life Sciences South China Agricultural UniversityGuangzhou510642China Key Laboratory of Plant Functional Genomics and Biotechnology of Guangdong Provincial Higher Education Institutions South China Agricultural UniversityGuangzhou5W642China State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources South China Agricultural UniversityGuangzhou5W642China

Male sterility(MS),characterized by functional defects in male organs or gametes,is an important agronomic trait for hybrid seed production,especially for self-pollinated crops such as rice(Oryza sativa L)(Chen and Liu,2014).Spontaneous MS mutants are rare and difficult to maintain in nature,thus limiting basicresearch and *** mutants are typically generated by physical,chemical,or biological mutagenesis(Wei et al,2013).Recently developed genome editing systems such as CRISPR/Cas9 allow efficient and timesaving knockout of endogenous genes at specific sites(Smith et al,2000;Moscou and Bogdanove,2009;Gasiunas et al.,2012).

关键词： anther-specific genes rice

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