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. P...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.展开更多
Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical...Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical, chemical and biological properties. However, limited information is available on the fractal characteristics of deep soil layers under different land use patterns. In this study, the fractal dimensions of particle size distribution（PSD） and micro-aggregates in the 0–500 cm soil profile and soil anti-erodibility in the 0–10 cm soil profile for 10 typical land use patterns were investigated in the Zhifanggou Watershed on the Loess Plateau, China. The 10 typical land use patterns were： slope cropland, two terraced croplands, check-dam cropland, woodland, two shrublands, orchard, artificial and natural grasslands. The results showed that the fractal dimensions of PSD and micro-aggregates were all significantly influenced by soil depths, land use patterns and their interaction. The plantations of shrubland, woodland and natural grassland increased the amount of larger micro-aggregates, and decreased the fractal dimensions of micro-aggregates in the 0–40 cm soil profile. And they also improved the aggregate state and aggregate degree and decreased dispersion rate in the 0–10 cm soil profile. The results indicated that fractal theory can be used to characterize soil structure under different land use patterns and fractal dimensions of micro-aggregates were more effective in this regard. The natural grassland may be the best choice for improving soil structure in the study area.展开更多
To better understand the effects of plastic film mulching on soil greenhouse gases（GHGs） emissions,we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize（Zea mays L.） fiel...To better understand the effects of plastic film mulching on soil greenhouse gases（GHGs） emissions,we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize（Zea mays L.） fields at Changwu station in Shaanxi,a semi-humid region,between 2012 and 2013.Gas samples were taken simultaneously every one week from non-mulched（BP） and plastic film-mulched（FM） field plots.The results showed that the concentration of GHGs varied distinctly at the soil-atmosphere interface and in the soil profile during the maize growing season（MS）.Both carbon dioxide（CO_2） and nitrous oxide（N_2O） concentrations increased with increasement of soil depth,while the methane（CH_4）concentrations decreased with increasement of soil depth.A strong seasonal variation pattern was found for CO_2 and N_2O concentrations,as compared to an inconspicuous seasonal variation of CH_4 concentrations.The mean CO_2 and N_2O concentrations were higher,but the mean CH_4 concentration in the soil profiles was lower in the FM plots than in the BP plots.The results of this study suggested that plastic film mulching significantly increased the potential emissions of CO_2and N_2O from the soil,and promoted CH_4 absorption by the soil,particularly during the MS.展开更多
Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determi...Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determined in six sizes of aggregates(>2,2-1,1-0.6,0.6-0.25,0.25-0.053,<0.053 mm).Significantly high(p<0.05)structural stability indexes(SSI)and ag-gregate stability indexes(ASI)were recorded in the topsoil horizon,which may be attributed to the high soil organic matter(SOM)content in aggregates from topsoil.In addition,ASI and SSI were positively correlated(r=0.569,p<0.05)with each other,which indicated that the stability of soil aggregates could contribute to the structural stability of bulk soil.Moreover,accumulation factors(AF),principal component analysis(PCA)and Pearson's correlation co-efficients were used for metal element assessment.The results indicated that SOM was not a key factor affecting the accumulation of Ca,Mg,Al,Fe,Mn,Pb,Cd and Cu in soil aggre-gates.In general,AF values for metal elements in microaggregates(<0.25 mm)were high,which showed that metals preferred to accumulate in fine soil aggregates.The PCA and Pearson's correlation coefficients indicated that soil parent materials primarily controlled the distribution of Al,Ca,Fe,Mg and Mn,while materials derived from technogenic sources have important impacts on the distribution of Cd,Cu and Pb in soil aggregates along the soil profile.展开更多
Salt balance in simulated soil columns was calculated on the basis of a large amount of long termobservation data. The results showed that under the climate conditions of senii-arid region of the Hnaiig-Huai-Hai Plain...Salt balance in simulated soil columns was calculated on the basis of a large amount of long termobservation data. The results showed that under the climate conditions of senii-arid region of the Hnaiig-Huai-Hai Plain, the soils in the columns were under salt accumulation conditions when the groundwater depthwas controlled at less than 2.0 m, and under desalinization conditions when at larger than 2.5 m. In the soilcolnmns with clay soil and silty loam soil intercalated with a clay layer, the aniount of salt accumulated wasfar less than that in the soil column with silty loain soil throughout the whole profile. Under no irrigationconditions crop planting niay increase groundwater evaporation and hence salt accumulation in soil, mforingthe soil colnmns under desalinization be under salt accumulation conditions.展开更多
It is generally accepted that the compositions and properties of soil organic matter （SOM） are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and it...It is generally accepted that the compositions and properties of soil organic matter （SOM） are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and its sub-fraction, humic acid （HA）, along two soil profiles, a yellow soil profile and a purplish soil profile, under the same climate and vegetation conditions were determined. Results indi- cate that the decomposition and humification degrees of SOM and HA of the purplish soils are higher than those of the corresponding yellow soils indicated by A/O-A ratios of HAs, TOCs and HA yields of bulk soil samples, neverthe- less, the development degree of the purplish soil is lower than that of the yellow soil. The variations of E4/E6 ratios of HAs along the soil profiles indicate the overall molecular sizes of HAs decreased downward along the soil profiles. A/O-A ratios of HAs decreased downward along both the soil profiles indicate that humification processes decrease downward along both the soil profiles. Leaching of SOM shows significant effects on the distribution and character- istics of HAs in the yellow soil profile but the purplish soil profile, which is consistent with the higher hydrophobicity of HAs in purplish soils, shows that the distribution char- acteristics of SOM along the soil profiles are a complex result of the combination of soil texture and characteristics of SOM itself. The remarkably different sand contents are concluded tentatively as one of reasons to the differentdistributions and dynamics of HAs along the soil profiles, however, to profoundly understand the evolution and transport of SOM along soil profiles needs more researches.展开更多
Selenium is a useful element in plant growth and it’s also an necessary ingredient for animal life.The inadequateness or excessiveness of selenium content and different forms of selenium in soil can affect the plant ...Selenium is a useful element in plant growth and it’s also an necessary ingredient for animal life.The inadequateness or excessiveness of selenium content and different forms of selenium in soil can affect the plant growth directly and then bring about further influence to the health of human and animals by food-chain.So it is significant to study the transport and transformation of the selenium in the soil profile.展开更多
Deep shear-wave velocity profiles at eight places in Lima Peru were estimated based on the inversion of dispersion curves. The dispersion curves were calculated from small and large microtremor arrays using two method...Deep shear-wave velocity profiles at eight places in Lima Peru were estimated based on the inversion of dispersion curves. The dispersion curves were calculated from small and large microtremor arrays using two methods： the F-k proposed by Capon （1969） and the CCA proposed by Cho et al. （2004）. For the purpose of large array measurement we introduced a new type of sensor. Important results are the relative shallow depths to the basement rock in the area classified as alluvial gravel that covers most of the area of Lima city; and the relative large depth to the bedrock in places identified as VSV and CMA. It is recommended that this study be complemented with PS loggings in order to verify the estimated profiles.展开更多
Elucidating the intricate dynamics of microbial communities across soil profiles is essential for deciphering the mechanisms by which microorganisms regulate ecosystem functions.However,previous studies on soil microo...Elucidating the intricate dynamics of microbial communities across soil profiles is essential for deciphering the mechanisms by which microorganisms regulate ecosystem functions.However,previous studies on soil microorganisms have predominantly centered on abundant taxa,neglecting the significant role of rare taxa in maintaining ecosystem functions.This study comprehensively analyzed the diversity and assembly processes of both rare and abundant microbial taxa in the profiles of Udic and Ustic Isohumosols in northeast China.We also explored the relative contribution of rare and abundant microbial taxa in maintaining ecosystem multifunctionality.Results showed that rare microbial taxa exhibited a higher diversity compared to abundant taxa,and rare microbial taxa occupied more central positions within networks.Furthermore,rare taxa displayed narrower ecological niche breadths and stronger phylogenetic signals,and their community assembly was predominantly governed by deterministic processes.In contrast,stochastic processes exert more pronounced influences on the assemblage of abundant taxa.Ecosystem multifunctionality was significantly reduced in deep soil horizons relative to the surface soil horizons.This is accompanied by close cooperation of microorganisms to cope with environmental stress in deep soils.This study highlights the pivotal role of rare microbial communities in shaping multifunctionality of ecosystems across the entire soil profiles.展开更多
The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Che...The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Cheng et C. D. Chu. The study was conducted in the Open Research Station of Changbai Mountain Forest Ecological System, The Chinese Academy of Sciences from 1999 to 2001. Four treatments were arranged in the rectangular open_top chambers (OTCs): ambient CO 2+no_seedling, 700 μmol/mol CO 2+no_seedling, ambient CO 2 +seedlings, 700 μmol/mol CO 2+seedlings. By collecting and analyzing soil gas synchronously, it was found that the dynamics of CO 2 profiles were related to the biological activity of seedlings. There were more roots distributed in the top soil and the boundary layer across soil and sand, which made more contributions to the CO 2 profiles due to respiration root. Compared with the ambient CO 2, elevated CO 2 led to the peak of CO 2 concentration distribution shifted from soil surface layer to the boundary layer as seasonally growing of seedling roots. It is suggested the gas_well system is an inexpensive, non_destructive and relatively sensitive method for study of soil CO 2 concentration profiles.展开更多
Aims Lignin is generally considered as an important indicator of soil organic carbon(SOC)storage and dynamics.to evaluate the effects of plant communities and soil depth on soil lignin is critical to better understand...Aims Lignin is generally considered as an important indicator of soil organic carbon(SOC)storage and dynamics.to evaluate the effects of plant communities and soil depth on soil lignin is critical to better understand forest carbon cycling.Methods We compared lignin content and chemical signature in three soil depths of four major plant communities in a subtropical forest,which located in the north part of Wuling Mountains,China.Lignin was measured using CuO oxidation method.Important Findings Both lignin content and its biochemical signature in plant litter varied among communities.However,these differences were mostly no longer exist in the upper soil layers.Lignin chemistry in soils inherited some of the biochemical signature of lignin in litter,but in a diminished magnitude.these results suggest that different plant communities had similar decomposition process with vary-ing rates,caused diminished differences in lignin content and its biochemical signature.Lignin content decreased with soil depth,but the biochemical signature of lignin was not significantly dif-ferent among soil layers for all communities,which suggests that vertical movement of lignin within the soil profile is very likely a key process causing this similar biochemical signature.these results emphasized the important roles of lignin inputs and soil eluviation in shaping lignin characteristics and distribution in forest soils,which pinpoint the urgent need to consider hydrological processes in studying forest soil carbon cycling.展开更多
The physical and chemical properties of soils are closely controlled by the climate factors and thus are significant for paleoclimate reconstruction. In this study, two adjacent soil profiles （LP and LPM） with diffe...The physical and chemical properties of soils are closely controlled by the climate factors and thus are significant for paleoclimate reconstruction. In this study, two adjacent soil profiles （LP and LPM） with different slopes from Yah＇an, Shaanxi Province, were investigated using magnetic methods to determine the impact of topography on magnetic properties of soil. Our results show that although LP and LPM have similar magnetic minerals and grain size distribution, both the average and max- imum magnetic susceptibility （Z） of LP are almost doubled compared to those of LPM. In addition, the ratios of susceptibility enhancement to the background （Ez） for LP and LPM are 2.27 and 2.04, respectively; the ratios of saturation isothermal rem- nant magnetization （SIRM） enhancement （EsIRM） for these two profiles are 1.80 and 1.86, respectively. The slopes of the linear regression trends between frequency-dependent susceptibility （ZFD） and ＂hard＂ isothermal remnant magnetization （HIRM） （ZFD/HIRM）, Anhysteretic remnant magnetization （ARM） and HIRM （ARM/HIRM）, are almost free from the effect of parent material. XFD/HIRMs for LP and LPM are 28.7×10 5 and 28.9×10 5 A m^-1, respectively; ARM/HIRMs are 0.35 and 0.33 for LP and LPM, respectively. These results demonstrate that parameters, ZFD/HIRM, ARM/HIRM, Ez and ESIRM, are affected less by parent material and topography, which are better than the Z for bulk samples to indicate the paleoclimatic conditions （e.g., the paleorainfall） in a large-scale region.展开更多
A field survey was conducted in a contaminated industrial site of southern Beijing,China to investigate the contents and distribution of the organochlorine pesticides(α-,β-,y-,δ-HCH,p,p'-DDT,p,p'-DDE,p,p...A field survey was conducted in a contaminated industrial site of southern Beijing,China to investigate the contents and distribution of the organochlorine pesticides(α-,β-,y-,δ-HCH,p,p'-DDT,p,p'-DDE,p,p'-DDD and o,p'-DDT)in the profiles of soil,and a health risk assessment was carded out with CalTOX multimedia exposure model.Results showed that mean concentrations of total hexachlorocyclohexane isomers(HCHs)and total dichlorodiphenyltrichloroethane isomers(DDXs)in soils were in the range of 13.20-148.71 mg/kg,and 3.02-67.43 mg/kg,respectively.Organochlorine pesticides(OCPs)content peaked in the surface and declined in soil profile with depth.The amounts of HCHs in three profiles of soil were larger than DDXs.Composition analysis indicated that there was a trend of degradation of OCPs in the site,but the mean of HCHs and DDXs concentration were over the state warning standard limit(HCHs,0.50 mg/kg;DDXs,0.50 mg/kg).According to current land use development,health risk assessment with CalTOX and Monte Carlo analysis showed that health risks mainly came from two exposure pathways:dermal uptake and inhalation,and the total risk values all exceeded the general acceptable health risk value(10-6).The sensitivity analysis indicated that five parameters significantly contributed to total risk.展开更多
Water-soluble rare earth elements (WSREEs) of four typical soil profiles in China were determined by using a high-resolution inductively coupled plasma mass spectrometer. Results showed that the contents of WSREEs dec...Water-soluble rare earth elements (WSREEs) of four typical soil profiles in China were determined by using a high-resolution inductively coupled plasma mass spectrometer. Results showed that the contents of WSREEs decreased from upper layer to lower layer of soils in the southern part of China with a high rainfall and low pH but increased for soils in the northern part of China with a low rainfall and relatively higher pH. Contents of WSREEs in soils were lower than 100 μg kg-1 in most casest and varied greatly with both different soils and different layers of the same profile. The highest content was 2816.3 μg kg-1 but the lowest was 17.6 μg kg-1 only. The content of individual rare earth iement (REE) in the soil solution also varied greatly with the highest one ranging from 8.4 to 1373 μg kg-1 for Ce and the lowest one from 0.05to 4.48 μg kg-1 for Lu. The sum of WSREEs in the first soil layers ranged from 121.5 to 345.6 μg kg-1.Great variations existed among ratios of REEs extracted with water to the total REEs of soils, ranging from 0.02×10-3 to 13.2×10-3. But as the upper layer was considered, the ratio showed only a small difference,ranging from 0.79×10-3 to 1.69×10-3.展开更多
Wildfires are complex natural phenomena that exert significant impacts on landscapes,societies,and economies.Understanding the concept of resilience is crucial in mitigating its possible negative impacts,as it involve...Wildfires are complex natural phenomena that exert significant impacts on landscapes,societies,and economies.Understanding the concept of resilience is crucial in mitigating its possible negative impacts,as it involves preparing for,responding to,and recovering from wildfires.This research aims to demonstrate the utility of in situ soil profile description in assessing land use resilience using an Analytic Hierarchy Process(AHP)through an expert panel survey.The study examines a catchment located in the Balearic Islands,considering two fire occurrences(once and twice),comparing abandoned agricultural terraces and natural hillslopes.The results demonstrated that the priority ranking of variables to assess soil profile resilience against wildfires,determined by a panel of 10 experts,identified horizon depth(25.1%),slope inclination(21.5%),and hydrological connectivity(16.6%)as the most crucial factors.Other variables,such as number and size of roots,structure of pedal soil material,size class structure,and rock fragments,also contributed to resilience but to a lesser extent,with scores ranging from 5.7%to 9.6%.Analyzing the priorities established by the experts using AHP,the results showed that the least resilient soil horizon was H1 of the control hillslope,especially under high and low connectivity processes,which aligned with the loss of superficial soil horizons after one and two wildfires.Hillslopes showed greater changes in resilience after occurring wildfires compared to terraces,with the most significant alterations occurring after the second wildfire event.This study addresses a significant knowledge gap in the field by highlighting the interconnectedness of wildfires,resilience,and land use,providing insights into land management strategies for wildfire-prone regions.展开更多
The contents and distribution of 20 polycyclic aromatic hydrocarbons （PAHs） and heterocyclic aromatic hydrocarbons （HAHs） were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high mole...The contents and distribution of 20 polycyclic aromatic hydrocarbons （PAHs） and heterocyclic aromatic hydrocarbons （HAHs） were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs （HMWPAHs） and the correlation between total organic carbon （TOC） and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil （〈 40 cm）, with a sharp content decrease at the vertical boundary of 30-40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.展开更多
In order to improve the precision of soil organic carbon (SOC) estimates, the sources of uncertainty in soil organic carbon density (SOCD) estimates and SOC stocks were examined using 363 soil profiles in Hebei Provin...In order to improve the precision of soil organic carbon (SOC) estimates, the sources of uncertainty in soil organic carbon density (SOCD) estimates and SOC stocks were examined using 363 soil profiles in Hebei Province, China, with three methods: the soil profile statistics (SPS), GIS-based soil type (GST), and kriging interpolation (KI). The GST method, utilizing both pedological professional knowledge and GIS technology, was considered the most accurate method of the three estimations, with SOCD estimates for SPS 10% lower and KI 10% higher. The SOCD range for GST was 84% wider than KI as KI smoothing effect narrowed the SOCD range. Nevertheless, the coefficient of variation for SOCD with KI (41.7%) was less than GST and SPS. Comparing SOCD’s lower estimates for SPS versus GST, the major sources of uncertainty were the conflicting area of proportional relations. Meanwhile, the fewer number of soil profiles and the necessity of using the smoothing effect with KI were its sources of uncertainty. Moreover, for local detailed variations of SOCD, GST was more advantageous in reflecting the distribution pattern than KI.展开更多
Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in...Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter-annual change. Soil moisture in 0-10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae, pine and the mixture of pine and arborvitae were measured in 2001,2005 and 2006. Soil moisture in about 0-3 m of cropland and about 0-2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually below these depths. In 0-2 m, soil moisture of cropland was significantly greater than those of all other vegetation types, and there were no si nificant differences among other vegetation types. In 2-10 m, there was no significant mois- ture difference between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point, and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration.展开更多
A tillage method of combining ridge with no-tillage(RNT)was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern,soil water stable aggregate distribution,nutrien...A tillage method of combining ridge with no-tillage(RNT)was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern,soil water stable aggregate distribution,nutrients stratification and yields of rice and post-rice crops.After flooded paddy field(FPF)was practiced with RNT for a long time,soil profile changed from G to A-P-G,and horizon G was shifted to a deeper position in the profile.Also the proportion of macroaggregate(>2 mm)increased,whereas the proportion of silt and clay(<0.053 mm)decreased under RNT,indicating a better soil structure that will prevent erosion.RNT helped to control leaching and significantly improved total N,P,K and organic matter in soil.The highest crop yields were found under RNT system every year,and total crop yields were higher under conventional paddy-upland rotation tillage(CR)than under FPF,except in 2003 and 2006 when serious drought occurred.RNT was proven to be a better tillage method for lowland rice-based cropping system.展开更多
Characterization of the vertical distribution of soil organic carbon(C), nitrogen(N), and phosphorus(P) may improve our ability to accurately estimate soil C, N, and P storage. Based on a database of 21 354 records in...Characterization of the vertical distribution of soil organic carbon(C), nitrogen(N), and phosphorus(P) may improve our ability to accurately estimate soil C, N, and P storage. Based on a database of 21 354 records in 74 long-term monitoring plots from 2004 to 2013 in the Chinese Ecosystem Research Network(CERN), we built fitting functions to quantify the vertical distribution of soil C, N, and P(up to 100 cm depth) in the typical Chinese terrestrial ecosystems. The decrease of soil C, N, and P content with depth can be well fitted with various mathematical functions. The fitting functions differed greatly between artificial(agriculture) and natural(desert, forest, and grassland) ecosystems, and also differed with respect to soil C, N, and P content. In both the artificial and natural ecosystems, the best fitting functions were exponential functions for C, quadratic functions for N, and quadratic functions for P. Furthermore, the stoichiometric ratios of soil C, N, and P were ranked in descending order: grassland > forest > agriculture > desert, and were also associated with climate. This study is the first to build the fitting functions for the profile distribution of soil C, N, and P in China at a national scale. Our findings provide a scientific basis to accurately assess the storage of C, N, and P in soils at a large scale, especially for the integrative analysis of historical data.展开更多
基金supported by Land Resource Investigation Project (GZTR20060201,GZTR20070201,and GZTR02-02) from China Geological Survey(CGS)
文摘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.
基金supported by the Strategic Technology Project of Chinese Academy of Sciences (XDA05060300)the Science and Technology R&D Program of Shaanxi Province (2011KJXX63)
文摘Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical, chemical and biological properties. However, limited information is available on the fractal characteristics of deep soil layers under different land use patterns. In this study, the fractal dimensions of particle size distribution（PSD） and micro-aggregates in the 0–500 cm soil profile and soil anti-erodibility in the 0–10 cm soil profile for 10 typical land use patterns were investigated in the Zhifanggou Watershed on the Loess Plateau, China. The 10 typical land use patterns were： slope cropland, two terraced croplands, check-dam cropland, woodland, two shrublands, orchard, artificial and natural grasslands. The results showed that the fractal dimensions of PSD and micro-aggregates were all significantly influenced by soil depths, land use patterns and their interaction. The plantations of shrubland, woodland and natural grassland increased the amount of larger micro-aggregates, and decreased the fractal dimensions of micro-aggregates in the 0–40 cm soil profile. And they also improved the aggregate state and aggregate degree and decreased dispersion rate in the 0–10 cm soil profile. The results indicated that fractal theory can be used to characterize soil structure under different land use patterns and fractal dimensions of micro-aggregates were more effective in this regard. The natural grassland may be the best choice for improving soil structure in the study area.
基金financially supported by the National Natural Science Foundation of China(31270553,51279197,41401343)the Special Fund for Agricultural Profession, China(201103003)
文摘To better understand the effects of plastic film mulching on soil greenhouse gases（GHGs） emissions,we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize（Zea mays L.） fields at Changwu station in Shaanxi,a semi-humid region,between 2012 and 2013.Gas samples were taken simultaneously every one week from non-mulched（BP） and plastic film-mulched（FM） field plots.The results showed that the concentration of GHGs varied distinctly at the soil-atmosphere interface and in the soil profile during the maize growing season（MS）.Both carbon dioxide（CO_2） and nitrous oxide（N_2O） concentrations increased with increasement of soil depth,while the methane（CH_4）concentrations decreased with increasement of soil depth.A strong seasonal variation pattern was found for CO_2 and N_2O concentrations,as compared to an inconspicuous seasonal variation of CH_4 concentrations.The mean CO_2 and N_2O concentrations were higher,but the mean CH_4 concentration in the soil profiles was lower in the FM plots than in the BP plots.The results of this study suggested that plastic film mulching significantly increased the potential emissions of CO_2and N_2O from the soil,and promoted CH_4 absorption by the soil,particularly during the MS.
基金This work was supported by the National Key Research and Development Project of China(No.2017YFD0800305).
文摘Different aggregates vary in their ability to retain or adsorb metals in soil.Five soil profiles were sampled from different soil horizons and grouped,and the concentrations of Al,Mg,Ca,Fe,Mn,Cd,Cu and Pb were determined in six sizes of aggregates(>2,2-1,1-0.6,0.6-0.25,0.25-0.053,<0.053 mm).Significantly high(p<0.05)structural stability indexes(SSI)and ag-gregate stability indexes(ASI)were recorded in the topsoil horizon,which may be attributed to the high soil organic matter(SOM)content in aggregates from topsoil.In addition,ASI and SSI were positively correlated(r=0.569,p<0.05)with each other,which indicated that the stability of soil aggregates could contribute to the structural stability of bulk soil.Moreover,accumulation factors(AF),principal component analysis(PCA)and Pearson's correlation co-efficients were used for metal element assessment.The results indicated that SOM was not a key factor affecting the accumulation of Ca,Mg,Al,Fe,Mn,Pb,Cd and Cu in soil aggre-gates.In general,AF values for metal elements in microaggregates(<0.25 mm)were high,which showed that metals preferred to accumulate in fine soil aggregates.The PCA and Pearson's correlation coefficients indicated that soil parent materials primarily controlled the distribution of Al,Ca,Fe,Mg and Mn,while materials derived from technogenic sources have important impacts on the distribution of Cd,Cu and Pb in soil aggregates along the soil profile.
文摘Salt balance in simulated soil columns was calculated on the basis of a large amount of long termobservation data. The results showed that under the climate conditions of senii-arid region of the Hnaiig-Huai-Hai Plain, the soils in the columns were under salt accumulation conditions when the groundwater depthwas controlled at less than 2.0 m, and under desalinization conditions when at larger than 2.5 m. In the soilcolnmns with clay soil and silty loam soil intercalated with a clay layer, the aniount of salt accumulated wasfar less than that in the soil column with silty loain soil throughout the whole profile. Under no irrigationconditions crop planting niay increase groundwater evaporation and hence salt accumulation in soil, mforingthe soil colnmns under desalinization be under salt accumulation conditions.
基金supported by National Major Research Program of China(2013CB956702)the National Science Foundation of China(41273149,41173129)+1 种基金the Science Foundation of Guizhou Province(20113109)the 100-Talent Program of CAS
文摘It is generally accepted that the compositions and properties of soil organic matter （SOM） are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and its sub-fraction, humic acid （HA）, along two soil profiles, a yellow soil profile and a purplish soil profile, under the same climate and vegetation conditions were determined. Results indi- cate that the decomposition and humification degrees of SOM and HA of the purplish soils are higher than those of the corresponding yellow soils indicated by A/O-A ratios of HAs, TOCs and HA yields of bulk soil samples, neverthe- less, the development degree of the purplish soil is lower than that of the yellow soil. The variations of E4/E6 ratios of HAs along the soil profiles indicate the overall molecular sizes of HAs decreased downward along the soil profiles. A/O-A ratios of HAs decreased downward along both the soil profiles indicate that humification processes decrease downward along both the soil profiles. Leaching of SOM shows significant effects on the distribution and character- istics of HAs in the yellow soil profile but the purplish soil profile, which is consistent with the higher hydrophobicity of HAs in purplish soils, shows that the distribution char- acteristics of SOM along the soil profiles are a complex result of the combination of soil texture and characteristics of SOM itself. The remarkably different sand contents are concluded tentatively as one of reasons to the differentdistributions and dynamics of HAs along the soil profiles, however, to profoundly understand the evolution and transport of SOM along soil profiles needs more researches.
文摘Selenium is a useful element in plant growth and it’s also an necessary ingredient for animal life.The inadequateness or excessiveness of selenium content and different forms of selenium in soil can affect the plant growth directly and then bring about further influence to the health of human and animals by food-chain.So it is significant to study the transport and transformation of the selenium in the soil profile.
文摘Deep shear-wave velocity profiles at eight places in Lima Peru were estimated based on the inversion of dispersion curves. The dispersion curves were calculated from small and large microtremor arrays using two methods： the F-k proposed by Capon （1969） and the CCA proposed by Cho et al. （2004）. For the purpose of large array measurement we introduced a new type of sensor. Important results are the relative shallow depths to the basement rock in the area classified as alluvial gravel that covers most of the area of Lima city; and the relative large depth to the bedrock in places identified as VSV and CMA. It is recommended that this study be complemented with PS loggings in order to verify the estimated profiles.
基金supported by the National Natural Science Foundation of China(Grant No.41977202)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA28020201)the Heilongjiang Provincial Natural Science Foundation of China(Grant No.ZD2022D001).
文摘Elucidating the intricate dynamics of microbial communities across soil profiles is essential for deciphering the mechanisms by which microorganisms regulate ecosystem functions.However,previous studies on soil microorganisms have predominantly centered on abundant taxa,neglecting the significant role of rare taxa in maintaining ecosystem functions.This study comprehensively analyzed the diversity and assembly processes of both rare and abundant microbial taxa in the profiles of Udic and Ustic Isohumosols in northeast China.We also explored the relative contribution of rare and abundant microbial taxa in maintaining ecosystem multifunctionality.Results showed that rare microbial taxa exhibited a higher diversity compared to abundant taxa,and rare microbial taxa occupied more central positions within networks.Furthermore,rare taxa displayed narrower ecological niche breadths and stronger phylogenetic signals,and their community assembly was predominantly governed by deterministic processes.In contrast,stochastic processes exert more pronounced influences on the assemblage of abundant taxa.Ecosystem multifunctionality was significantly reduced in deep soil horizons relative to the surface soil horizons.This is accompanied by close cooperation of microorganisms to cope with environmental stress in deep soils.This study highlights the pivotal role of rare microbial communities in shaping multifunctionality of ecosystems across the entire soil profiles.
文摘The gas_well system permanently installed in the soil was adopted for studying the dynamic relationship between CO 2 profiles and seedling root growth of Pinus sylvestris var. sylvestriformis (Takenouchi) Cheng et C. D. Chu. The study was conducted in the Open Research Station of Changbai Mountain Forest Ecological System, The Chinese Academy of Sciences from 1999 to 2001. Four treatments were arranged in the rectangular open_top chambers (OTCs): ambient CO 2+no_seedling, 700 μmol/mol CO 2+no_seedling, ambient CO 2 +seedlings, 700 μmol/mol CO 2+seedlings. By collecting and analyzing soil gas synchronously, it was found that the dynamics of CO 2 profiles were related to the biological activity of seedlings. There were more roots distributed in the top soil and the boundary layer across soil and sand, which made more contributions to the CO 2 profiles due to respiration root. Compared with the ambient CO 2, elevated CO 2 led to the peak of CO 2 concentration distribution shifted from soil surface layer to the boundary layer as seasonally growing of seedling roots. It is suggested the gas_well system is an inexpensive, non_destructive and relatively sensitive method for study of soil CO 2 concentration profiles.
基金This study was supported by the National Natural Science Foundation of China(31270515,31400463)the Chinese National Key Development Program for Basic Research(2014CB954004).
文摘Aims Lignin is generally considered as an important indicator of soil organic carbon(SOC)storage and dynamics.to evaluate the effects of plant communities and soil depth on soil lignin is critical to better understand forest carbon cycling.Methods We compared lignin content and chemical signature in three soil depths of four major plant communities in a subtropical forest,which located in the north part of Wuling Mountains,China.Lignin was measured using CuO oxidation method.Important Findings Both lignin content and its biochemical signature in plant litter varied among communities.However,these differences were mostly no longer exist in the upper soil layers.Lignin chemistry in soils inherited some of the biochemical signature of lignin in litter,but in a diminished magnitude.these results suggest that different plant communities had similar decomposition process with vary-ing rates,caused diminished differences in lignin content and its biochemical signature.Lignin content decreased with soil depth,but the biochemical signature of lignin was not significantly dif-ferent among soil layers for all communities,which suggests that vertical movement of lignin within the soil profile is very likely a key process causing this similar biochemical signature.these results emphasized the important roles of lignin inputs and soil eluviation in shaping lignin characteristics and distribution in forest soils,which pinpoint the urgent need to consider hydrological processes in studying forest soil carbon cycling.
基金supported by the National Natural Science Foundation of China(Grant Nos.40125013 and 40821091)Q S Liu was supported by the 100-talent Program of the Chinese Academy of Sciences
文摘The physical and chemical properties of soils are closely controlled by the climate factors and thus are significant for paleoclimate reconstruction. In this study, two adjacent soil profiles （LP and LPM） with different slopes from Yah＇an, Shaanxi Province, were investigated using magnetic methods to determine the impact of topography on magnetic properties of soil. Our results show that although LP and LPM have similar magnetic minerals and grain size distribution, both the average and max- imum magnetic susceptibility （Z） of LP are almost doubled compared to those of LPM. In addition, the ratios of susceptibility enhancement to the background （Ez） for LP and LPM are 2.27 and 2.04, respectively; the ratios of saturation isothermal rem- nant magnetization （SIRM） enhancement （EsIRM） for these two profiles are 1.80 and 1.86, respectively. The slopes of the linear regression trends between frequency-dependent susceptibility （ZFD） and ＂hard＂ isothermal remnant magnetization （HIRM） （ZFD/HIRM）, Anhysteretic remnant magnetization （ARM） and HIRM （ARM/HIRM）, are almost free from the effect of parent material. XFD/HIRMs for LP and LPM are 28.7×10 5 and 28.9×10 5 A m^-1, respectively; ARM/HIRMs are 0.35 and 0.33 for LP and LPM, respectively. These results demonstrate that parameters, ZFD/HIRM, ARM/HIRM, Ez and ESIRM, are affected less by parent material and topography, which are better than the Z for bulk samples to indicate the paleoclimatic conditions （e.g., the paleorainfall） in a large-scale region.
基金supported by the National Natural Sci-ence Foundation of China(No.70433001)the Knowledge Innovation Project of the Chinese Academy of Sciences(No.KZCX2-YW-422,324)
文摘A field survey was conducted in a contaminated industrial site of southern Beijing,China to investigate the contents and distribution of the organochlorine pesticides(α-,β-,y-,δ-HCH,p,p'-DDT,p,p'-DDE,p,p'-DDD and o,p'-DDT)in the profiles of soil,and a health risk assessment was carded out with CalTOX multimedia exposure model.Results showed that mean concentrations of total hexachlorocyclohexane isomers(HCHs)and total dichlorodiphenyltrichloroethane isomers(DDXs)in soils were in the range of 13.20-148.71 mg/kg,and 3.02-67.43 mg/kg,respectively.Organochlorine pesticides(OCPs)content peaked in the surface and declined in soil profile with depth.The amounts of HCHs in three profiles of soil were larger than DDXs.Composition analysis indicated that there was a trend of degradation of OCPs in the site,but the mean of HCHs and DDXs concentration were over the state warning standard limit(HCHs,0.50 mg/kg;DDXs,0.50 mg/kg).According to current land use development,health risk assessment with CalTOX and Monte Carlo analysis showed that health risks mainly came from two exposure pathways:dermal uptake and inhalation,and the total risk values all exceeded the general acceptable health risk value(10-6).The sensitivity analysis indicated that five parameters significantly contributed to total risk.
文摘Water-soluble rare earth elements (WSREEs) of four typical soil profiles in China were determined by using a high-resolution inductively coupled plasma mass spectrometer. Results showed that the contents of WSREEs decreased from upper layer to lower layer of soils in the southern part of China with a high rainfall and low pH but increased for soils in the northern part of China with a low rainfall and relatively higher pH. Contents of WSREEs in soils were lower than 100 μg kg-1 in most casest and varied greatly with both different soils and different layers of the same profile. The highest content was 2816.3 μg kg-1 but the lowest was 17.6 μg kg-1 only. The content of individual rare earth iement (REE) in the soil solution also varied greatly with the highest one ranging from 8.4 to 1373 μg kg-1 for Ce and the lowest one from 0.05to 4.48 μg kg-1 for Lu. The sum of WSREEs in the first soil layers ranged from 121.5 to 345.6 μg kg-1.Great variations existed among ratios of REEs extracted with water to the total REEs of soils, ranging from 0.02×10-3 to 13.2×10-3. But as the upper layer was considered, the ratio showed only a small difference,ranging from 0.79×10-3 to 1.69×10-3.
基金supported by the research project CGL2017-88200-R,titled"Functional Hydrological and Sediment Connectivity in Mediterranean Catchments:Global Change Scenarios–MEDhyCON_2,"funded by the Spanish Ministry of Science,Innovation,and Universities,the Spanish Agency of Research (AEI)the European Regional Development Funds (ERDF)funded by COST Action (grant no. CA18135),supported by COST (European Cooperation in Science and Technology),during a Short-Term Scientific Mission (STSM) conducted by Jesús Rodrigo-Comino
文摘Wildfires are complex natural phenomena that exert significant impacts on landscapes,societies,and economies.Understanding the concept of resilience is crucial in mitigating its possible negative impacts,as it involves preparing for,responding to,and recovering from wildfires.This research aims to demonstrate the utility of in situ soil profile description in assessing land use resilience using an Analytic Hierarchy Process(AHP)through an expert panel survey.The study examines a catchment located in the Balearic Islands,considering two fire occurrences(once and twice),comparing abandoned agricultural terraces and natural hillslopes.The results demonstrated that the priority ranking of variables to assess soil profile resilience against wildfires,determined by a panel of 10 experts,identified horizon depth(25.1%),slope inclination(21.5%),and hydrological connectivity(16.6%)as the most crucial factors.Other variables,such as number and size of roots,structure of pedal soil material,size class structure,and rock fragments,also contributed to resilience but to a lesser extent,with scores ranging from 5.7%to 9.6%.Analyzing the priorities established by the experts using AHP,the results showed that the least resilient soil horizon was H1 of the control hillslope,especially under high and low connectivity processes,which aligned with the loss of superficial soil horizons after one and two wildfires.Hillslopes showed greater changes in resilience after occurring wildfires compared to terraces,with the most significant alterations occurring after the second wildfire event.This study addresses a significant knowledge gap in the field by highlighting the interconnectedness of wildfires,resilience,and land use,providing insights into land management strategies for wildfire-prone regions.
基金supported by the National NaturalScience Foundation of China (No. 40473045)
文摘The contents and distribution of 20 polycyclic aromatic hydrocarbons （PAHs） and heterocyclic aromatic hydrocarbons （HAHs） were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs （HMWPAHs） and the correlation between total organic carbon （TOC） and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil （〈 40 cm）, with a sharp content decrease at the vertical boundary of 30-40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.
基金Project supported by the Knowledge Innovation Project in Leading Edge Fields, Chinese Academy of Sciences(No. ISSASIP0201), the National Key Basic Research Support Foundation of China (No. G1999011810) and the KnowledgeInnovation Project in Resource and
文摘In order to improve the precision of soil organic carbon (SOC) estimates, the sources of uncertainty in soil organic carbon density (SOCD) estimates and SOC stocks were examined using 363 soil profiles in Hebei Province, China, with three methods: the soil profile statistics (SPS), GIS-based soil type (GST), and kriging interpolation (KI). The GST method, utilizing both pedological professional knowledge and GIS technology, was considered the most accurate method of the three estimations, with SOCD estimates for SPS 10% lower and KI 10% higher. The SOCD range for GST was 84% wider than KI as KI smoothing effect narrowed the SOCD range. Nevertheless, the coefficient of variation for SOCD with KI (41.7%) was less than GST and SPS. Comparing SOCD’s lower estimates for SPS versus GST, the major sources of uncertainty were the conflicting area of proportional relations. Meanwhile, the fewer number of soil profiles and the necessity of using the smoothing effect with KI were its sources of uncertainty. Moreover, for local detailed variations of SOCD, GST was more advantageous in reflecting the distribution pattern than KI.
基金National Key Basic Research Special Foundation Project of China, No.2007CB407204National Natural Science Foundation of China, No.40471082
文摘Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter-annual change. Soil moisture in 0-10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae, pine and the mixture of pine and arborvitae were measured in 2001,2005 and 2006. Soil moisture in about 0-3 m of cropland and about 0-2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually below these depths. In 0-2 m, soil moisture of cropland was significantly greater than those of all other vegetation types, and there were no si nificant differences among other vegetation types. In 2-10 m, there was no significant mois- ture difference between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point, and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration.
基金Project supported by the National Natural Science Foundation of China(No.40501033)the National Key Technologies R&D Program for the 11th Five-Year Plan of China(No.2007BAD87B10)
文摘A tillage method of combining ridge with no-tillage(RNT)was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern,soil water stable aggregate distribution,nutrients stratification and yields of rice and post-rice crops.After flooded paddy field(FPF)was practiced with RNT for a long time,soil profile changed from G to A-P-G,and horizon G was shifted to a deeper position in the profile.Also the proportion of macroaggregate(>2 mm)increased,whereas the proportion of silt and clay(<0.053 mm)decreased under RNT,indicating a better soil structure that will prevent erosion.RNT helped to control leaching and significantly improved total N,P,K and organic matter in soil.The highest crop yields were found under RNT system every year,and total crop yields were higher under conventional paddy-upland rotation tillage(CR)than under FPF,except in 2003 and 2006 when serious drought occurred.RNT was proven to be a better tillage method for lowland rice-based cropping system.
基金under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05050702)National Natural Science Foundation of China(No.31270519,31470506)Kezhen Distinguished Talents in Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences(No.2013RC102)
文摘Characterization of the vertical distribution of soil organic carbon(C), nitrogen(N), and phosphorus(P) may improve our ability to accurately estimate soil C, N, and P storage. Based on a database of 21 354 records in 74 long-term monitoring plots from 2004 to 2013 in the Chinese Ecosystem Research Network(CERN), we built fitting functions to quantify the vertical distribution of soil C, N, and P(up to 100 cm depth) in the typical Chinese terrestrial ecosystems. The decrease of soil C, N, and P content with depth can be well fitted with various mathematical functions. The fitting functions differed greatly between artificial(agriculture) and natural(desert, forest, and grassland) ecosystems, and also differed with respect to soil C, N, and P content. In both the artificial and natural ecosystems, the best fitting functions were exponential functions for C, quadratic functions for N, and quadratic functions for P. Furthermore, the stoichiometric ratios of soil C, N, and P were ranked in descending order: grassland > forest > agriculture > desert, and were also associated with climate. This study is the first to build the fitting functions for the profile distribution of soil C, N, and P in China at a national scale. Our findings provide a scientific basis to accurately assess the storage of C, N, and P in soils at a large scale, especially for the integrative analysis of historical data.
