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Characteristics of CO_2 in unsaturated zone(～90 m) of loess tableland, Northwest China

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Acta Geochimica 2017年第3期36卷 489-493页

作者： Chao Song Guilin Han Yingchun Shi Congqiang Liu Pan Wang School of Water Resources and Environment China University of Geosciences (Beijing) The Institute of Hydrogeology and Environmental Geology Chinese Academy of Geological Sciences

In order to observe CO_2 characteristics in the unsaturated zone of loess tableland and further understand the carbon cycle,a series of tubes for gas monitoring and sampling were installed in an approximately 90-m deep Qiushe loess section of Lingtai County,Northwestern *** results show that the concentration of CO_2 was higher in loess than in the atmosphere,reaching a maximum of 6970 lmol·mol^(-1).CO_2 concentrations in loess were higher in summer than in *** CO_2 in loess was related to organic carbon decomposed by microbes,and to the CaCO_3–H_2O–CO_2 system in the interface between the saturated and unsaturated zones.

关键词： unsaturated zone Soil CO2 Carbon stock in deep loess Quantitative paleoclimate reconstruction Loess

MODELING STUDY ON REMOVAL OF NITRATE IN WATER SYSTEM BY BACTERIA TRANSPLANTED IN unsaturated zone

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Transactions of Tianjin University 1999年第1期5卷 12-15页

作者：赵林王榕树林学钰天津大学化工学院长春科技大学 130026

With a view to treating the nitrate pollution in water systems,this article presents a novel method for eliminating nitrate from wastewater by bacteria through unsaturated zone. First,highly efficient denitrifiers suitable for underground environment have been studied based on the biochemical characterization and denitrifying mechanism of microorganisms. Then the nitrate-eliminating modeling study in soil columns was carried out with the obtained denitrifier. The results show that the nitrate-eeliminating efficiency can reach 98%,so it has practical value in controlling nitrate pollution in water systems.

关键词： water system unsaturated zone bacteria nitrate eliminate

Contribution of groundwater to the formation of sand dunes in the Badain Jaran Desert, China

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Journal of Arid Land 2023年第11期15卷 1340-1354页

作者： WANG Wang CHEN Jiaqi CHEN Jiansheng WANG Tao ZHAN Lucheng ZHANG Yitong MA Xiaohui College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China School of Computer and Information Hohai UniversityNanjing 210098China Water Science Research Institute Hohai UniversityNanjing 211100China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Water Affairs Integrated Service Centre of Alagxa League Inner Mongolia Autonomous RegionAlagxa League 750300China

The tallest sand dune worldwide is located in the Badain Jaran Desert(BJD),China,and has been standing for thousands of *** studies have conducted limited physical exploration and excavation on the formation of sand dunes and have proposed three viewpoints,that is,bedrock control,wind dominance,and groundwater maintenance with no unified ***,this study analyzed the underlying bedding structure of sand dunes in the *** the bedrock of sand dunes is uplifted and wind controls the shape of dunes,the main cause of dune formation is groundwater that maintains the deposition of calcareous sandstone and accumulation of aeolian *** to water transport model and vapor transports in the unsaturated zone of sand dunes,capillary water transport height is limited with film water constituting the main form of water in *** properties and temperature of groundwater showed that aquifers in different basins receive relatively independent recharge from deep sources in the *** of dune formation mechanism is of considerable importance in understanding groundwater circulation and provides a new perspective on water management in arid desert areas.

关键词： sand dune formation groundwater unsaturated zone water content desert water resource

Soil water movement and deep drainage through thick vadose zones on the northern slope of the Tianshan Mountain: Croplands *** lands

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China Geology 2020年第1期3卷 113-123页

作者： Fang-qiang Sun Li-he Yin Wu-hui Jia Jun Zhang Xiao-yong Wang Li-feng Zhu Xin-xin Zhang Xiao-ping Tang Jia-qiu Dong Xi’an Center of Geological Survey China Geological SurveyMinistry of Natural ResourcesXi’an 710054China School of Water Resources and Environment China University of GeosciencesBeijing 100083China Chinese Academy of Geological Sciences China Geological SurveyMinistry of Natural ResourcesBeijing 100037China

Regional aridity is increasing under global climate change,and therefore the sustainable use of water resources has drawn attention from scientists and the ***-use changes can have a significant impact on groundwater recharge in arid regions,and quantitative assessment of the impact is key to sustainable groundwater resources *** this study,the changes of groundwater recharge after the conversion of natural lands to croplands were investigated and compared in inland and arid region,i.e.,the northern slope of the Tianshan *** isotopes suggest that soil water in topsoil(<2 m)has experienced stronger evaporation under natural lands than croplands,and then moves downward as a piston *** was estimated by the tracer-based mass balance method,i.e.,chloride and *** rates under natural conditions estimated by the chloride mass balance(CMB)method were estimated to be 0.07 mm/a in deserts and 0.4 mm/a in *** contrast,the estimated groundwater recharge ranged from 61.2 mm/a to 44.8 mm/a in croplands,indicating that groundwater recharge would increase significantly after land changes from natural lands to irrigated croplands in arid *** estimated by the sulfate mass balance method is consistent with that from the CMB method,indicating that sulfate is also a good tracer capable of estimating groundwater recharge.

关键词： Land-use Soil water Groundwater recharge Deep drainage unsaturated zone Arid regions Cropland Natural land Groundwater survey engineering Tianshan Mountain China

Modeling for Volatilization and Bioremediation of Toluene-contaminated Soil by Bioventing

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Chinese Journal of Chemical Engineering 2011年第2期19卷 340-348页

作者：隋红李鑫钢 National Engineering Research Center for Distillation Technology Tianjin University Tianjin 300072 China School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China

A two-dimensional numerical model is developed to simulate the flow,transport and biodegradation of toluene during bioventing （BV） processes in the unsaturated *** simulation for a single well BV system is used to illustrate the effect of air injection rate on remediation *** air is injected into the vadose zone to create a positive *** results show that air injection rate is a primary parameter governing the dispersal,redistribution and surface loss of *** injection rates of 81.504 m3·d-1 （Run 1） and 407.52 m3·d-1 （Run 2）,the total removed mass of toluene is 169.14 kg and 170.59 kg *** of volatilization to bio-degradation in Run 1 and Run 2 are 0.57︰1 and 0.89︰1,respectively,indicating that lower air injection rate enhances the biodegradation efficiency *** injection rate should be optimized to meet oxygen demand and to minimize the operational cost.

关键词： bioventing biodegradation unsaturated zone toluene remediation

Estimation of Hydraulic Conductivity of Soils at a Watershed-Scale Using Porchet’s Method: Application in the Olezoa Waterhed, Yaounde, Cameroon

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International Journal of Geosciences 2016年第3期7卷 397-408页

作者： André Firmin Bon Auguste Ombolo Guillaume Ewodo Mboudou Jules Rémy Ndam Ngoupayou Georges Emmanuel Ekodeck Department of Climatology Hydrology and Soil Science Higher Institute of the Sahel University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Science University of Yaounde I Yaounde Cameroon Department of Hydraulics and Water Control Higher Institute of the Sahel University of Maroua Maroua Cameroon

Contamination analysis of the unsaturated zone requires information on the spatial variability of hydraulic conductivity. Two types of hydraulic tests (variable and constant charge) were identified to estimate the spatial variability of the hydraulic conductivity of the surface portion of the unsaturated zone in the Olezoa watershed. These tests were performed on 100 holes at depths ranging between 50 and 90 cm, spread throughout the watershed. The hydraulic conductivity values obtained at 50 and 90 cm are close to the absolute value for each method. However, they show a difference of 10-1 m/s between the two types of test regardless of the depth of investigation. The representation of data in the graph indicates a staircase quartile distribution for the variable charge test. The test at constant charge, rather presents a log normal distribution which is also supported by the Kolmogorov-Smirnov test. Hydraulic conductivities have a random component and a spatial organization which results from soil and/or morphological factors. This organization thus permits the distinction of zones which could show high pollution risk.

关键词： unsaturated zone Quartile Graphs Hydraulic Conductivity Olezoa

unsaturated Flow Drying Bed(UFDB):An Alternative for Treatment of Septic Tanks Sludge

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Journal of Water Resource and Protection 2014年第5期6卷 454-462页

作者： Gnagne Théophile Yéo Ténénan Martial Kouamé Yao Francis Konan Koffi Félix Faculty of Science and Environmental Management University Nangui AbrogouaAbidjanCote d’Ivoire Water and Sanitation for Africa National Representation of Cote d’IvoireAbidjanCote d’Ivoire Faculty of Environment University Jean Lorougnon GUEDE of DaloaDaloaCote d’Ivoire

unsaturated Flow Drying Bed (UFDB) principles are based on the ones of wastewater treatment by infiltration-percolation on the one hand and septic tanks sludge solar-drying beds on the other hand. With UFDB, sludge charges are split with low heights, leading to the drying of suspended solids in 2 days, and the infiltration of the flow of liquid in unsaturated middle. For average charges reaching 12.5 cm/d, the treatment efficiency of total oxygen demand and Total Kjeldahl Nitrogen, respectively 95 and 96%, correspond to a treatment capacity of 0.5 kg of O2/d/m2 of drying area. Bacteria reductions of 4 Ulog are obtained from filtrates outlet, with average fecal coliforms charges less than 103 CFU/100 ml. Monitoring the hydrodynamic behavior through rates, moisture, organic matter and respiratory activity demonstrates that the clogging of the massifs is linked to a biofilm growth within them. A four week resting period allows biofilm resorption. Thus, the drying of the infiltration surface in two days, the elimination of carbon, nitrogen and bacterial pollutions, as well as the reversibility of clogging show that UFDB is a credible alternative for the treatment of septic tank sludge in the socio-economic context and climate of tropical Africa.

关键词： Sludge Clogging Drying Bed unsaturated zone Aeration Pores

Estimating groundwater recharge following land-use change using chloride mass balance of soil profiles:a case study at Guyuan and Xifeng in the Loess Plateau of China

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Estimating groundwater recharge following land-use change us...

Groundwater recharge and dynamics in northern China implications for sustainable utilization of groundwater

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： Tianming Huang Zhonghe Pang Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beituchengxilu Rd,Beijing 100029,China

Groundwater recharge is affected by land use in (semi)arid areas.A new application of the chloride-mass-balance approach has been developed to estimate the reduction in groundwater recharge following land-use change by comparing chloride concentrations below the root zone and above the base of the chloride accumulation zone,before and after the land-use *** sites in the Loess Plateau of central China have been selected for *** from the Guyuan terrace region show that groundwater recharge beneath natural sparse small-grass was 100 mm/year,but the conversion to winter wheat about 100 years ago has reduced groundwater recharge to 55 mm/*** the Xifeng Loess Plain the conversion from winter wheat,with groundwater recharge at 33 mm/year,to apple orchard 7 years ago has led to chloride accumulation to 5 m below land surface, suggesting the recharge rate has been *** is in agreement with previous studies in these areas which have shown that the regional afforestation and other land-use conversions have resulted in deep soil desiccation and have caused an upper boundary to form with low matrix potential,thus preventing the soil moisture from actually recharging the aquifer.

关键词： Groundwater recharge/water budget unsaturated zone Chloride mass balance Land-use change China

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Groundwater recharge and dynamics in northern China implicat...