Knowledge on spatial distribution and sampling size optimization of soil copper (Cu) could lay solid foundations for environmetal quality survey of agricultural soils at county scale. In this investigation, cokrigin...Knowledge on spatial distribution and sampling size optimization of soil copper (Cu) could lay solid foundations for environmetal quality survey of agricultural soils at county scale. In this investigation, cokriging method was used to conduct the interpolation of Cu concentraiton in cropland soil in Shuangliu County, Sichuan Province, China. Based on the original 623 physicochmically measured soil samples, 560, 498, and 432 sub-samples were randomly selected as target variable and soil organic matter (SOM) of the whole original samples as auxiliary variable. Interpolation results using Cokriging under different sampling numbers were evaluated for their applicability in estimating the spatial distribution of soil Cu at county sacle. The results showed that the root mean square error (RMSE) produced by Cokriging decreased from 0.9 to 7.77%, correlation coefficient between the predicted values and the measured increased from 1.76 to 9.76% in comparison with the ordinary Kriging under the corresponding sample sizes. The prediction accuracy using Cokriging was still higher than original 623 data using ordinary Kriging even as sample size reduced 10%, and their interpolation maps were highly in agreement. Therefore, Cokriging was proven to be a more accurate and economic method which could provide more information and benefit for the studies on spatial distribution of soil pollutants at county scale.展开更多
Soil type maps at the scale of I Z 1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China. However, the soil property maps ...Soil type maps at the scale of I Z 1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China. However, the soil property maps produced through conventional direct linking method usually suffer low accuracy as well as the lack of spatial details within a soil type polygon. This paper presents an effective method to produce detailed soil property map based on representative samples which were extracted from each polygon on the 1 : 1 000 000 soil type map. The representative sample of each polygon is defined as the location that can represent the largest area within the polygon. The representativeness of a candidate sample is determined by calculating the soil-forming environment condition similarities between the sample and other locations. Once the representative sample of each polygon has been chosen, the property values of the existing typical samples are assigned to the corresponding representative samples with the same soil type. Finally, based on these representative samples, the detailed soil property map could be produced by using existing digital soil mapping methods. The case study in XuanCheng City, Anhui Province of China, demonstrated the proposed method could produce soil property map at a higher level of spatial details and accuracy: 1) The soil organic matter (SOM) map produced based on the representative samples can not only depict the detailed spatial distribution of SOM within a soil type polygon but also largely reduce the abrupt change of soil property at the boundaries of two adjacent polygons. 2) The Root Mean Squared Error (RMSE) of the SOM map based on the representative samples is 1.61, and it is 1.37 for the SOM map produced by using conventional direct linking method. Therefore, the proposed method is an effective approach to produce spatial detailed soil property map with higher accuracy for environment simulation models.展开更多
Soil disturbance includes the change of stress state and the damage of soil structure.The field testing indices reflect the combined effect of both changes and it is difficult to identify the soil structure disturbanc...Soil disturbance includes the change of stress state and the damage of soil structure.The field testing indices reflect the combined effect of both changes and it is difficult to identify the soil structure disturbance directly from these indices.In the present study,the small-strain shear modulus is used to characterize soil structure disturbance by normalizing the effective stress and void ratio based on Hardin equation.The procedure for evaluating soil sampling disturbance in the field and the further disturbance during the subsequent consolidation process in laboratory test is proposed,and then validated by a case study of soft clay ground.Downhole seismic testing in the field,portable piezoelectric bender elements for the drilled sample and bender elements in triaxial apparatus for the consolidated sample were used to monitor the shear wave velocity of the soil from intact to disturbed and even remolded states.It is found that soil sampling disturbance degree by conventional thin-wall sampler is about 30%according to the proposed procedure,which is slightly higher than that from the modified volume compression method proposed by Hong and Onitsuka(1998).And the additional soil disturbance induced by consolidation in laboratory could reach about 50%when the consolidation pressure is far beyond the structural yield stress,and it follows the plastic volumetric strain quite well.展开更多
Through the analysis on the migratory diffusion process of atmospheric pollutants,we proposed to seek atmospheric pollutant source with surface soil sample of data.Based on Gaussian plume model and deposition model,at...Through the analysis on the migratory diffusion process of atmospheric pollutants,we proposed to seek atmospheric pollutant source with surface soil sample of data.Based on Gaussian plume model and deposition model,atmospheric pollutants distribution model was deduced,with which a schema matching source seeking model was established.The model was used to seek the pollutant source by using the arsenic data in the surface soil sample of a city.展开更多
In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external di...In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external diameterof auger tip is larger than that of sampling tube. Therefore, adhesion and cutting resistance can be reducedby limiting connection areas between sampler and the soil. Such a new structure makes it possible to bewidely used for the production of a series of special soil samplers.展开更多
This study was designed to screen and characterize antibiotic producing bacteria and fungi from soil samples from a waste dump site in Enugu. The molecular characterization of the isolates was performed by using Zymo ...This study was designed to screen and characterize antibiotic producing bacteria and fungi from soil samples from a waste dump site in Enugu. The molecular characterization of the isolates was performed by using Zymo Research Quick-DNA fungi/bacteria miniprep kit. The bacteria isolates were <i>Providencia stuartii</i>, <i>Providencia alcalifaciens.</i> <i>Bacillus sp.</i>, <i>Streptococcus sp.</i>, <i>Micrococcus sp.</i>, and <i>Staphylococcus sp</i> while <i>Aspergillus fumigatus</i> and <i>Aspergillus niger</i> were fungal isolates. The efficacy of the Crude Extract (CE) of the antibiotics produced was tested against species of <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. The CE of antibiotics when compared with a conventional antibiotic (Ciprofloxacin) showed lower antimicrobial activity. The minimum inhibitory concentration of the crude extracts ranged between 12.5% and 25% concentrations while the minimum bactericidal concentration ranged from 25% and 50% concentrations. The findings suggest that these organisms have the potential to produce antibiotics and could be harnessed by pharmaceutical industries for the production of newer antibiotics.展开更多
An Nd:YAG single pulse nanosecond laser of 532 nm wavelength with an 8 ns pulse width was projected on the soil samples collected from the campus of Bengbu College under 1 standard atmospheric pressure. Laser-induced ...An Nd:YAG single pulse nanosecond laser of 532 nm wavelength with an 8 ns pulse width was projected on the soil samples collected from the campus of Bengbu College under 1 standard atmospheric pressure. Laser-induced breakdown spectroscopy at different sample temperatures was achieved. The intensity and signal-to-noise ratio (SNR) changes of different characteristic spectral lines could be analyzed when the sample temperature changes.The evolution of plasma electron temperature and electron density with the sample temperature was analyzed through Boltzmann oblique line method and Stark broadening method.The cause of the radiation enhancement of laser-induced metal plasma was discussed. Experimental results demonstrated that the spectral intensity, SNR, the electron temperature and electron density of plasma are positively related to the sample temperature, and reach saturation at 100℃.展开更多
A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been develope...A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of Arsenic (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.025 - 0.1 M H2SO4) solution with Arsenic (V) in absolute ethanol to produce highly fluorescent oxidized product (λex = 303 nm;λem = 365 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.025 - 0.1 M H2SO4) for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001 - 800-μgL-1 of As, having a detection limit of 0.1-ngL-1;the quantification limit of the reaction system was found to be 1-ngL-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexion agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN, etc.) do not interfere in the determination. The developed method was successfully used in the determination of arsenic in several Certified Reference Materials (alloys, steels, ores, human urine, hair, nails, bovine liver and sediments) as well as in some biological fluids (human blood, urine, hair, nail and milk), soil samples, food samples (vegetables, fruits, rice, corn and wheat), solutions containing both arsenic (III) and arsenic (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and soil samples were comparable with both ICP-OES & AHG-AAS and were found to be in excellent agreement.展开更多
The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten ...The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten regions was found to be 51.86 ± 7.14, 75.56 ± 10.95 and 128.98 ± 6.88 Bq/kg respectively. The results obtained for the corresponding nuclides 226Ra and 232Th are above the worldwide average values (35 and 30 Bq/kg) while 40K was smaller than worldwide average (400 Bq/kg). The average outdoor absorbed dose and the annual effective dose rates due to 226Ra, 232Th and 40K were observed to be 21.51 ± 2.93 nGy/h and 0.297 ±.03 mSv/y respectively, which are lower than world average values (60 nGy/h and 0.8 mSv/y). The radium equivalent activity and external hazard indices were found less than the world wide average values.展开更多
A new spectrofluorimetric reagent 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been synthesized and characterized through novel reaction techniques. A very simple, ultra-sensitive and highly selective non-extractive n...A new spectrofluorimetric reagent 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been synthesized and characterized through novel reaction techniques. A very simple, ultra-sensitive and highly selective non-extractive new spectrofluorimetric method for the determination of vanadium at Pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of vanadium (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.0035 - 0.0085 M H2SO4) solution within vanadium (V) in 20% ethanol to produce highly fluorescent oxidized product (λex = 319 nm;λem = 371 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.0035 - 0.0085 M H2SO4) for the period between 5 min and 24 h. Linear calibration graphs were obtained for 0.001 - 600-μg·L-1 of V, having a detection limit of 0.3-ng·L-1;the quantification limit of the reaction system was found to be 3-ng·L-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexing agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN- etc.) do not interfere in the determination. The developed method was successfully used in the determination of vanadium in several Certified Reference Materials (alloys, steels, serum, bovine liver, drinking water, soil and sediments) as well as in some environmental waters (potable and polluted), biological fluids (human blood, urine, hair and milk), soil samples and food samples (vegetables, rice and wheat) solutions containing both vanadium (IV) and vanadium (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetable samples were comparable with inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic-absorption spectrophotometer (AAS) was found to be in excellent agreement.展开更多
The sampling auger used in lunar sampling and return mission is to transmit power and convey soil, and its performance is the key factor of the whole mission. However, there is currently a lack of the optimization res...The sampling auger used in lunar sampling and return mission is to transmit power and convey soil, and its performance is the key factor of the whole mission. However, there is currently a lack of the optimization research on soil conveying volume and power consumption models in auger structure design. To provide the drilled object, the simulation lunar soil, whose physical and mechanical property is the same as the real soil, is made by reducing soil void ratio. The models are formulated to analyze the influence of auger structure parameters on power consumption and soil conveying volume. To obtain the optimized structure parameters of auger, the multi-objective optimization functions of the maximum soil conveying volume and minimum power consumption are developed. To verify the correctness of the models, the performances of different augers drilling simulation soil are tested. The test results demonstrate that the power consumption of optimized auger is the lowest both in theory and test, and the experimental results of soil conveying volume are in agreement with theoretical analysis. Consequently, a new method for designing a lunar sampling auger is proposed which includes the models of soil conveying volume and transportation power consumption, the optimization of structure parameters and the comparison tests. This method provides a reference for sampling auger designing of the Chinese Lunar Sample Mission.展开更多
The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimat...The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimate auxiliary variables: cokriging and regression-kriging, and using the salinity data from the first two stages as auxiliary variables, the methods both improved the interpolation of soil salinity in coastal saline land. The prediction accuracy of the three methods was observed under different sampling density of the target variable by comparison with another group of 80 validation sample points, from which the root-mean-square error (RMSE) and correlation coefficient (r) between the predicted and measured values were calculated. The results showed, with the help of auxiliary data, whatever the sample size of the target variable may be, cokriging and regression-kriging performed better than ordinary kriging. Moreover, regression-kriging produced on average more accurate predictions than cokriging. Compared with the kriging results, cokriging improved the estimations by reducing RMSE from 23.3 to 29% and increasing r from 16.6 to 25.5%, regression-kriging improved the estimations by reducing RMSE from 25 to 41.5% and increasing r from 16.8 to 27.2%. Therefore, regression-kriging shows promise for improved prediction for soil salinity and reduction of soil sampling intensity considerably while maintaining high prediction accuracy. Moreover, in regression-kriging, the regression model can have any form, such as generalized linear models, non-linear models or tree-based models, which provide a possibility to include more ancillary variables.展开更多
Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping...Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping project were sent to China's IGGE (Institute of Geophysical and Geochemical Exploration) laboratory and composited to 190 samples according to the 160 kin x 160 km GNT (Global Terrestrial Network) cells. In addition to the FOREGS elemental analysis package, Au, Pt, Pd, B, Ge, Br, CI, Se, N, Li and F were also analyzed by using the IGGE's 76 element analytical scheme. Geochemical data statistics, scatter plotting, and geochemical map compilation tech- niques have been employed to investigate differences between FOREGS and IGGE analytical results. The results of two datasets, the IGGE's analysis data for composited samples, and the FOREGS average data of samples in each GNT cell, agree extremely well lor about 23 elements, viz: SiO2, St, Al2O3, Zr, Ba, Fe2O3, Ti, Rb, Mn, Gd, CaO, Ga, MgO, P, Pb, Na2O, Y, Th, As, U Sc, Cr, and Co. There are slight differences between-laboratory biases shown as proportional errors between the datasets for Ni, K2O, Tb, Tl, Cu, S, Sin, La, Ce, Pr, Nd, Eu, Ho, Er, Tin, Yb, Lu, Ta, Nb, HE and Dy. For Cd, Cs, Be, Sb, In, Mo, I, Sn, and Te, the correlation of the two datasets and the similarity of the geochemical maps are fairly good, but obvious biases exist between the two datasets at values near detection limits.展开更多
Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 s...Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).展开更多
This paper presents novel approaches to address the complex issues associated with preservation, transportation, and tensile testing of the vegetation root samples needed for the enhancement of soil and prevent erosio...This paper presents novel approaches to address the complex issues associated with preservation, transportation, and tensile testing of the vegetation root samples needed for the enhancement of soil and prevent erosion. Readily availability of no equipment for in-situ assessment of the roots’ contribution to soil strength forces the researchers to transport the root samples to the lab for testing and estimating the contribution to the soil shear strength. Moreover, the standard procedures and apparatuses available in the public domain are regrettably suitable for testing of relatively stiffer materials. Therefore, conducting the tensile test of roots using off-the-shelf equipment often causes premature failure of the soft tissues and produces an erratic result, which ultimately leads to unrealistic soil shear strength. The experimental work replaced the traditional jaw type grips by innovative 3D-printed mold or metal ring with silicone, epoxy, and hot-glue to ensure a minimal degree of damage to the roots. Other scopes of the study include a comparison between fresh and refrigerated samples, the effect of sample storage temperature, pH, and Optimum Effective Root Area (OERA) per unit area of soil. Initial study conducted on the Bermuda grass (Cynodon dactylon) roots involved comparison for different approaches based on the gripping technic to select the best method. Finally, the paper included the results of tensile strength test performed on Spartina alterniflora root samples following the suggested guidelines thus helping better evaluation of root embedded soil shear strength, enhancing the resistance against soil erosion, and conserving the ecosystem.展开更多
The world needs around 150 Pg of negative carbon emissions to mitigate climate change. Global soils may provide a stable, sizeable reservoir to help achieve this goal by sequestering atmospheric carbon dioxide as soil...The world needs around 150 Pg of negative carbon emissions to mitigate climate change. Global soils may provide a stable, sizeable reservoir to help achieve this goal by sequestering atmospheric carbon dioxide as soil organic carbon (SOC). In turn, SOC can support healthy soils and provide a multitude of ecosystem benefits. To support SOC sequestration, researchers and policy makers must be able to precisely measure the amount of SOC in a given plot of land. SOC measurement is typically accomplished by taking soil cores selected at random from the plot under study, mixing (compositing) some of them together, and analyzing (assaying) the composited samples in a laboratory. Compositing reduces assay costs, which can be substantial. Taking samples is also costly. Given uncertainties and costs in both sampling and assay along with a desired estimation precision, there is an optimal composite size that will minimize the budget required to achieve that precision. Conversely, given a fixed budget, there is a composite size that minimizes uncertainty. In this paper, we describe and formalize sampling and assay for SOC and derive the optima for three commonly used assay methods: dry combustion in an elemental analyzer, loss-on-ignition, and mid-infrared spectroscopy. We demonstrate the utility of this approach using data from a soil survey conducted in California. We give recommendations for practice and provide software to implement our framework.展开更多
Based on the experience of soil sampling in Yuanzegou small watershed,several matters needing attention in soil field sampling are summarized.This paper focuses on the layout of sampling points,soil sample collection,...Based on the experience of soil sampling in Yuanzegou small watershed,several matters needing attention in soil field sampling are summarized.This paper focuses on the layout of sampling points,soil sample collection,soil sample preparation and matters needing attention about potential factors in soil field sampling,with a view to providing reference for undergraduates,master students or non-subject experimenters who are about to carry out experiments in this discipline.展开更多
Ultrasonic aided slurry sampling hydride generation atomic fluorescence spectrometry (USS-HG-AFS) was developed for the determination of Hg in soil samples from a sewage-irrigated farm. 500 mg grounded soil was susp...Ultrasonic aided slurry sampling hydride generation atomic fluorescence spectrometry (USS-HG-AFS) was developed for the determination of Hg in soil samples from a sewage-irrigated farm. 500 mg grounded soil was suspended in agar solution by an ultrasound water bath before the HG-AFS determination. The results for the reference material of soil (serial number GBW-07411) agreed satisfactorily with the certified values. Results obtained by the developed procedure compared well with those after traditional acid digestion of samples. The detection limit are 6.7ngL-1 for Hg respectively, with average relative standard deviation values of 6.4% for analysis of a series of soil samples of different origin. The recoveries of the anatytes varied in the range from 95 to 107%. This observation has stimulated interest in fast, accurate and sensitive analytical methods for determination of metals in soil.展开更多
基金supported by the Youth Foundation from Sichuan Education Bureau (2006B009)Key Project from Sichuan Education Bureau (2006A008)Sichuan Youth Science & Technology Foundation,China (06ZQ026-020)
文摘Knowledge on spatial distribution and sampling size optimization of soil copper (Cu) could lay solid foundations for environmetal quality survey of agricultural soils at county scale. In this investigation, cokriging method was used to conduct the interpolation of Cu concentraiton in cropland soil in Shuangliu County, Sichuan Province, China. Based on the original 623 physicochmically measured soil samples, 560, 498, and 432 sub-samples were randomly selected as target variable and soil organic matter (SOM) of the whole original samples as auxiliary variable. Interpolation results using Cokriging under different sampling numbers were evaluated for their applicability in estimating the spatial distribution of soil Cu at county sacle. The results showed that the root mean square error (RMSE) produced by Cokriging decreased from 0.9 to 7.77%, correlation coefficient between the predicted values and the measured increased from 1.76 to 9.76% in comparison with the ordinary Kriging under the corresponding sample sizes. The prediction accuracy using Cokriging was still higher than original 623 data using ordinary Kriging even as sample size reduced 10%, and their interpolation maps were highly in agreement. Therefore, Cokriging was proven to be a more accurate and economic method which could provide more information and benefit for the studies on spatial distribution of soil pollutants at county scale.
基金Under the auspices of Program of International Science & Technology Cooperation,Ministry of Science and Technology of China(No.2010DFB24140)National Natural Science Foundation of China(No.41023010,41001298)National High Technology Research and Development Program of China(No.2011AA120305)
文摘Soil type maps at the scale of I Z 1 000 000 are used extensively to provide soil spatial distribution information for soil erosion assessment and watershed management models in China. However, the soil property maps produced through conventional direct linking method usually suffer low accuracy as well as the lack of spatial details within a soil type polygon. This paper presents an effective method to produce detailed soil property map based on representative samples which were extracted from each polygon on the 1 : 1 000 000 soil type map. The representative sample of each polygon is defined as the location that can represent the largest area within the polygon. The representativeness of a candidate sample is determined by calculating the soil-forming environment condition similarities between the sample and other locations. Once the representative sample of each polygon has been chosen, the property values of the existing typical samples are assigned to the corresponding representative samples with the same soil type. Finally, based on these representative samples, the detailed soil property map could be produced by using existing digital soil mapping methods. The case study in XuanCheng City, Anhui Province of China, demonstrated the proposed method could produce soil property map at a higher level of spatial details and accuracy: 1) The soil organic matter (SOM) map produced based on the representative samples can not only depict the detailed spatial distribution of SOM within a soil type polygon but also largely reduce the abrupt change of soil property at the boundaries of two adjacent polygons. 2) The Root Mean Squared Error (RMSE) of the SOM map based on the representative samples is 1.61, and it is 1.37 for the SOM map produced by using conventional direct linking method. Therefore, the proposed method is an effective approach to produce spatial detailed soil property map with higher accuracy for environment simulation models.
基金This study is partly supported by the National Natural Science Foundation of China(Grant Nos.51978613,52278374 and 51988101).All these funding grants are greatly acknowledged.
文摘Soil disturbance includes the change of stress state and the damage of soil structure.The field testing indices reflect the combined effect of both changes and it is difficult to identify the soil structure disturbance directly from these indices.In the present study,the small-strain shear modulus is used to characterize soil structure disturbance by normalizing the effective stress and void ratio based on Hardin equation.The procedure for evaluating soil sampling disturbance in the field and the further disturbance during the subsequent consolidation process in laboratory test is proposed,and then validated by a case study of soft clay ground.Downhole seismic testing in the field,portable piezoelectric bender elements for the drilled sample and bender elements in triaxial apparatus for the consolidated sample were used to monitor the shear wave velocity of the soil from intact to disturbed and even remolded states.It is found that soil sampling disturbance degree by conventional thin-wall sampler is about 30%according to the proposed procedure,which is slightly higher than that from the modified volume compression method proposed by Hong and Onitsuka(1998).And the additional soil disturbance induced by consolidation in laboratory could reach about 50%when the consolidation pressure is far beyond the structural yield stress,and it follows the plastic volumetric strain quite well.
文摘Through the analysis on the migratory diffusion process of atmospheric pollutants,we proposed to seek atmospheric pollutant source with surface soil sample of data.Based on Gaussian plume model and deposition model,atmospheric pollutants distribution model was deduced,with which a schema matching source seeking model was established.The model was used to seek the pollutant source by using the arsenic data in the surface soil sample of a city.
文摘In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external diameterof auger tip is larger than that of sampling tube. Therefore, adhesion and cutting resistance can be reducedby limiting connection areas between sampler and the soil. Such a new structure makes it possible to bewidely used for the production of a series of special soil samplers.
文摘This study was designed to screen and characterize antibiotic producing bacteria and fungi from soil samples from a waste dump site in Enugu. The molecular characterization of the isolates was performed by using Zymo Research Quick-DNA fungi/bacteria miniprep kit. The bacteria isolates were <i>Providencia stuartii</i>, <i>Providencia alcalifaciens.</i> <i>Bacillus sp.</i>, <i>Streptococcus sp.</i>, <i>Micrococcus sp.</i>, and <i>Staphylococcus sp</i> while <i>Aspergillus fumigatus</i> and <i>Aspergillus niger</i> were fungal isolates. The efficacy of the Crude Extract (CE) of the antibiotics produced was tested against species of <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. The CE of antibiotics when compared with a conventional antibiotic (Ciprofloxacin) showed lower antimicrobial activity. The minimum inhibitory concentration of the crude extracts ranged between 12.5% and 25% concentrations while the minimum bactericidal concentration ranged from 25% and 50% concentrations. The findings suggest that these organisms have the potential to produce antibiotics and could be harnessed by pharmaceutical industries for the production of newer antibiotics.
基金supported by the National Natural Science Foundation of China(No.11604003)Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology(OMST201703)the Natural Science Foundations of Bengbu College(No.2017ZR11zd)
文摘An Nd:YAG single pulse nanosecond laser of 532 nm wavelength with an 8 ns pulse width was projected on the soil samples collected from the campus of Bengbu College under 1 standard atmospheric pressure. Laser-induced breakdown spectroscopy at different sample temperatures was achieved. The intensity and signal-to-noise ratio (SNR) changes of different characteristic spectral lines could be analyzed when the sample temperature changes.The evolution of plasma electron temperature and electron density with the sample temperature was analyzed through Boltzmann oblique line method and Stark broadening method.The cause of the radiation enhancement of laser-induced metal plasma was discussed. Experimental results demonstrated that the spectral intensity, SNR, the electron temperature and electron density of plasma are positively related to the sample temperature, and reach saturation at 100℃.
文摘A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of Arsenic (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.025 - 0.1 M H2SO4) solution with Arsenic (V) in absolute ethanol to produce highly fluorescent oxidized product (λex = 303 nm;λem = 365 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.025 - 0.1 M H2SO4) for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001 - 800-μgL-1 of As, having a detection limit of 0.1-ngL-1;the quantification limit of the reaction system was found to be 1-ngL-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexion agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN, etc.) do not interfere in the determination. The developed method was successfully used in the determination of arsenic in several Certified Reference Materials (alloys, steels, ores, human urine, hair, nails, bovine liver and sediments) as well as in some biological fluids (human blood, urine, hair, nail and milk), soil samples, food samples (vegetables, fruits, rice, corn and wheat), solutions containing both arsenic (III) and arsenic (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and soil samples were comparable with both ICP-OES & AHG-AAS and were found to be in excellent agreement.
文摘The activity concentration of natural radioactivity for soil samples collected from western and mid Libyan regions were measured using HPGe detector. The average activity concentration of 226Ra, 232Th and 40K for ten regions was found to be 51.86 ± 7.14, 75.56 ± 10.95 and 128.98 ± 6.88 Bq/kg respectively. The results obtained for the corresponding nuclides 226Ra and 232Th are above the worldwide average values (35 and 30 Bq/kg) while 40K was smaller than worldwide average (400 Bq/kg). The average outdoor absorbed dose and the annual effective dose rates due to 226Ra, 232Th and 40K were observed to be 21.51 ± 2.93 nGy/h and 0.297 ±.03 mSv/y respectively, which are lower than world average values (60 nGy/h and 0.8 mSv/y). The radium equivalent activity and external hazard indices were found less than the world wide average values.
文摘A new spectrofluorimetric reagent 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been synthesized and characterized through novel reaction techniques. A very simple, ultra-sensitive and highly selective non-extractive new spectrofluorimetric method for the determination of vanadium at Pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of vanadium (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.0035 - 0.0085 M H2SO4) solution within vanadium (V) in 20% ethanol to produce highly fluorescent oxidized product (λex = 319 nm;λem = 371 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.0035 - 0.0085 M H2SO4) for the period between 5 min and 24 h. Linear calibration graphs were obtained for 0.001 - 600-μg·L-1 of V, having a detection limit of 0.3-ng·L-1;the quantification limit of the reaction system was found to be 3-ng·L-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexing agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN- etc.) do not interfere in the determination. The developed method was successfully used in the determination of vanadium in several Certified Reference Materials (alloys, steels, serum, bovine liver, drinking water, soil and sediments) as well as in some environmental waters (potable and polluted), biological fluids (human blood, urine, hair and milk), soil samples and food samples (vegetables, rice and wheat) solutions containing both vanadium (IV) and vanadium (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetable samples were comparable with inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic-absorption spectrophotometer (AAS) was found to be in excellent agreement.
基金Supported by National Defense Science and Technology Major Project(Grant Nos.TY3Q20110001,TY3Q20110005)College Discipline Innovation Wisdom Plan of China(111 Project,Grant No.B07018)National Natural Science Foundation of China(Grant No.51105092)
文摘The sampling auger used in lunar sampling and return mission is to transmit power and convey soil, and its performance is the key factor of the whole mission. However, there is currently a lack of the optimization research on soil conveying volume and power consumption models in auger structure design. To provide the drilled object, the simulation lunar soil, whose physical and mechanical property is the same as the real soil, is made by reducing soil void ratio. The models are formulated to analyze the influence of auger structure parameters on power consumption and soil conveying volume. To obtain the optimized structure parameters of auger, the multi-objective optimization functions of the maximum soil conveying volume and minimum power consumption are developed. To verify the correctness of the models, the performances of different augers drilling simulation soil are tested. The test results demonstrate that the power consumption of optimized auger is the lowest both in theory and test, and the experimental results of soil conveying volume are in agreement with theoretical analysis. Consequently, a new method for designing a lunar sampling auger is proposed which includes the models of soil conveying volume and transportation power consumption, the optimization of structure parameters and the comparison tests. This method provides a reference for sampling auger designing of the Chinese Lunar Sample Mission.
基金the National Natural Science Foundation of China (40571066, 40001008)the Postdoctoral Science Foundation of China (20060401048) the Key Program of Science and Technology Bureau of Zhejiang Province, China 030523).
文摘The spatial estimation for soil properties was improved and sampling intensities also decreased in terms of incorporated auxiliary data. In this study, kriging and two interpolation methods were proven well to estimate auxiliary variables: cokriging and regression-kriging, and using the salinity data from the first two stages as auxiliary variables, the methods both improved the interpolation of soil salinity in coastal saline land. The prediction accuracy of the three methods was observed under different sampling density of the target variable by comparison with another group of 80 validation sample points, from which the root-mean-square error (RMSE) and correlation coefficient (r) between the predicted and measured values were calculated. The results showed, with the help of auxiliary data, whatever the sample size of the target variable may be, cokriging and regression-kriging performed better than ordinary kriging. Moreover, regression-kriging produced on average more accurate predictions than cokriging. Compared with the kriging results, cokriging improved the estimations by reducing RMSE from 23.3 to 29% and increasing r from 16.6 to 25.5%, regression-kriging improved the estimations by reducing RMSE from 25 to 41.5% and increasing r from 16.8 to 27.2%. Therefore, regression-kriging shows promise for improved prediction for soil salinity and reduction of soil sampling intensity considerably while maintaining high prediction accuracy. Moreover, in regression-kriging, the regression model can have any form, such as generalized linear models, non-linear models or tree-based models, which provide a possibility to include more ancillary variables.
基金given to the Ministry of Land and Resources and the Ministry of Science and Technology for the research funding of the projects: SinoProbe 04 and 863 Project 2007AA06Z133
文摘Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping project were sent to China's IGGE (Institute of Geophysical and Geochemical Exploration) laboratory and composited to 190 samples according to the 160 kin x 160 km GNT (Global Terrestrial Network) cells. In addition to the FOREGS elemental analysis package, Au, Pt, Pd, B, Ge, Br, CI, Se, N, Li and F were also analyzed by using the IGGE's 76 element analytical scheme. Geochemical data statistics, scatter plotting, and geochemical map compilation tech- niques have been employed to investigate differences between FOREGS and IGGE analytical results. The results of two datasets, the IGGE's analysis data for composited samples, and the FOREGS average data of samples in each GNT cell, agree extremely well lor about 23 elements, viz: SiO2, St, Al2O3, Zr, Ba, Fe2O3, Ti, Rb, Mn, Gd, CaO, Ga, MgO, P, Pb, Na2O, Y, Th, As, U Sc, Cr, and Co. There are slight differences between-laboratory biases shown as proportional errors between the datasets for Ni, K2O, Tb, Tl, Cu, S, Sin, La, Ce, Pr, Nd, Eu, Ho, Er, Tin, Yb, Lu, Ta, Nb, HE and Dy. For Cd, Cs, Be, Sb, In, Mo, I, Sn, and Te, the correlation of the two datasets and the similarity of the geochemical maps are fairly good, but obvious biases exist between the two datasets at values near detection limits.
基金This research was supported by the National Key R and D Program of China(2016YFC0500901 and 2016YFC0500907)the National Natural Science Foundation of China(Grant Nos.31971466 and 41807525)the One Hundred Person Project of the Chinese Academy of Sciences(Y551821).
文摘Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).
文摘This paper presents novel approaches to address the complex issues associated with preservation, transportation, and tensile testing of the vegetation root samples needed for the enhancement of soil and prevent erosion. Readily availability of no equipment for in-situ assessment of the roots’ contribution to soil strength forces the researchers to transport the root samples to the lab for testing and estimating the contribution to the soil shear strength. Moreover, the standard procedures and apparatuses available in the public domain are regrettably suitable for testing of relatively stiffer materials. Therefore, conducting the tensile test of roots using off-the-shelf equipment often causes premature failure of the soft tissues and produces an erratic result, which ultimately leads to unrealistic soil shear strength. The experimental work replaced the traditional jaw type grips by innovative 3D-printed mold or metal ring with silicone, epoxy, and hot-glue to ensure a minimal degree of damage to the roots. Other scopes of the study include a comparison between fresh and refrigerated samples, the effect of sample storage temperature, pH, and Optimum Effective Root Area (OERA) per unit area of soil. Initial study conducted on the Bermuda grass (Cynodon dactylon) roots involved comparison for different approaches based on the gripping technic to select the best method. Finally, the paper included the results of tensile strength test performed on Spartina alterniflora root samples following the suggested guidelines thus helping better evaluation of root embedded soil shear strength, enhancing the resistance against soil erosion, and conserving the ecosystem.
文摘The world needs around 150 Pg of negative carbon emissions to mitigate climate change. Global soils may provide a stable, sizeable reservoir to help achieve this goal by sequestering atmospheric carbon dioxide as soil organic carbon (SOC). In turn, SOC can support healthy soils and provide a multitude of ecosystem benefits. To support SOC sequestration, researchers and policy makers must be able to precisely measure the amount of SOC in a given plot of land. SOC measurement is typically accomplished by taking soil cores selected at random from the plot under study, mixing (compositing) some of them together, and analyzing (assaying) the composited samples in a laboratory. Compositing reduces assay costs, which can be substantial. Taking samples is also costly. Given uncertainties and costs in both sampling and assay along with a desired estimation precision, there is an optimal composite size that will minimize the budget required to achieve that precision. Conversely, given a fixed budget, there is a composite size that minimizes uncertainty. In this paper, we describe and formalize sampling and assay for SOC and derive the optima for three commonly used assay methods: dry combustion in an elemental analyzer, loss-on-ignition, and mid-infrared spectroscopy. We demonstrate the utility of this approach using data from a soil survey conducted in California. We give recommendations for practice and provide software to implement our framework.
文摘Based on the experience of soil sampling in Yuanzegou small watershed,several matters needing attention in soil field sampling are summarized.This paper focuses on the layout of sampling points,soil sample collection,soil sample preparation and matters needing attention about potential factors in soil field sampling,with a view to providing reference for undergraduates,master students or non-subject experimenters who are about to carry out experiments in this discipline.
文摘Ultrasonic aided slurry sampling hydride generation atomic fluorescence spectrometry (USS-HG-AFS) was developed for the determination of Hg in soil samples from a sewage-irrigated farm. 500 mg grounded soil was suspended in agar solution by an ultrasound water bath before the HG-AFS determination. The results for the reference material of soil (serial number GBW-07411) agreed satisfactorily with the certified values. Results obtained by the developed procedure compared well with those after traditional acid digestion of samples. The detection limit are 6.7ngL-1 for Hg respectively, with average relative standard deviation values of 6.4% for analysis of a series of soil samples of different origin. The recoveries of the anatytes varied in the range from 95 to 107%. This observation has stimulated interest in fast, accurate and sensitive analytical methods for determination of metals in soil.