检索结果-南通市图书馆

Numerical Approaches to Identification of Characteristic Soil Layers in an Urban Environment

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2008年第3期18卷 335-343页

作者： YUAN Da-gang zhang gan-lin GONG Zi-Tong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of SciencesNanjing 210008 （China） Graduate School of the Chinese Academy of Sciences Beijing 100049 （China） College of Resource and Environmental Sciences Sichuan Agricultural University Ya＇an 625014 （China）

Pedogenetic soil horizons are one of the fundamental building blocks of modern soil classification; however, in soils of urban areas which are often strongly disturbed by human activities, horizons are difficult to distinguish but substitutive morphological layers may be identified. To identify the characteristic soil layers in an urban environment, 224 soil layers of 36 in-situ pedons were examined and described in urban and suburban Nanjing, and 27 variables were extracted for multivariate analysis. Three groups and six subdivisions were identified by TwoStep cluster analysis combined with hierarchical cluster analysis based on factor scores. Soil forming factors and soil forming processes could be interpreted from the principal component analysis （PCA） of variables, cluster analysis of soil layers, and discriminant analysis of soil layer groups and their subdivisions. Parent materials, moisture regimes, organic matter accumulation, and especially nutrient accumulation were the main causes of characteristic soil layer formations. The numerical approaches used in this study were useful tools for characteristic soil layer identification of urban soils.

关键词： characteristic soil layer multivariate analysis numerical soil classification urban soils

Predicting soil depth in a large and complex area using machine learning and environmental correlations

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2022年第8期21卷 2422-2434页

作者： LIU Feng YANG Fei ZHAO Yu-guo zhang gan-lin LI De-cheng State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008P.R.China University of the Chinese Academy of Sciences Beijing 100049P.R.China Key Laboratory of Watershed Geographic Science Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008P.R.China

Soil depth is critical for eco-hydrological modeling,carbon storage calculation and land ***,its spatial variation is poorly understood and rarely *** a limited number of sparse samples,how to predict soil depth in a large area of complex landscapes is still an *** study constructed an ensemble machine learning model,i.e.,quantile regression forest,to quantify the relationship between soil depth and environmental *** model was then combined with a rich set of environmental covariates to predict spatial variation of soil depth and straightforwardly estimate the associated predictive uncertainty in the 140000 km^(2)Heihe River basin of northwestern China.A total of 275 soil depth observation points and 26 covariates were *** results showed a model predictive accuracy with coefficient of determination(R)of 0.587 and root mean square error(RMSE)of 2.98 cm(square root scale),i.e.,almost 60% of soil depth variation *** resulting soil depth map clearly exhibited regional patterns as well as local *** deep soils occurred in low lying landscape positions such as valley bottoms and plains while shallow soils occurred in high and steep landscape positions such as hillslopes,ridges and *** oases had much deeper soils than outside semi-desert areas,the middle of an alluvial plain had deeper soils than its margins,and the middle of a lacustrine plain had shallower soils than its *** predictive uncertainty mainly occurred in areas with a lack of soil survey *** pedogenic and geomorphic processes contributed to the shaping of soil depth pattern of this basin but the latter was *** findings may be applicable to other similar basins in cold and arid regions around the world.

关键词： digital soil mapping spatial variation uncertainty machine learning soil-landscape model soil depth

An integrated method of selecting environmental covariates for predictive soil depth mapping

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2019年第2期18卷 301-315页

作者： LU Yuan-yuan LIU Feng ZHAO Yu-guo SONG Xiao-dong zhang gan-lin State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008P.R.China University of Chinese Academy of Sciences Beijing 100049P.R.China

Environmental covariates are the basis of predictive soil *** selection determines the performance of soil mapping to a great extent,especially in cases where the number of soil samples is limited but soil spatial heterogeneity is *** this study,we proposed an integrated method to select environmental covariates for predictive soil depth ***,candidate variables that may influence the development of soil depth were selected based on pedogenetic ***,three conventional methods(Pearson correlation analysis(PsCA),generalized additive models(GAMs),and Random Forest(RF))were used to generate optimal combinations of environmental ***,three optimal combinations were integrated to produce a final combination based on the importance and occurrence frequency of each environmental *** tested this method for soil depth mapping in the upper reaches of the Heihe River Basin in Northwest China.A total of 129 soil sampling sites were collected using a representative sampling strategy,and RF and support vector machine(SVM)models were used to map soil *** results showed that compared to the set of environmental covariates selected by the three conventional selection methods,the set of environmental covariates selected by the proposed method achieved higher mapping *** combination from the proposed method obtained a root mean square error(RMSE)of 11.88 cm,which was 2.25–7.64 cm lower than the other methods,and an R^2 value of 0.76,which was 0.08–0.26 higher than the other *** results suggest that our method can be used as an alternative to the conventional methods for soil depth mapping and may also be effective for mapping other soil properties.

关键词： environmental covariate selection integrated method predictive soil mapping soil depth

Progress in Significant Soil Science Fields of China over the Last Three Decades: A Review

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第1期21卷 1-10页

作者： ZHAO Qi-Guo HE Ji-Zheng YAN Xiao-Yuan zhang Bin zhang gan-lin CAI Zu-Cong State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 (China) State Key Laboratory of Urban and Regional Ecology Research Centre for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 (China) Key Laboratory of Plant Nutrition and Nutrient Cycling of the Ministry of Agriculture of China Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Beijing 100081 (China)

Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enhancing soil productivity under intensive *** the aim of promoting the application of soil science knowledge,this paper reviews the achievements of Chinese scientists in soil resource use and management,soil fertility,global change mitigation and soil biology over the last 30 *** this period,soil resource science has provided essential support for the use and exploitation of Chinese soil resources,and has itself developed through introduction of new theories such as Soil Taxonomy and new technologies such as remote *** fertility science has contributed to the alleviation and elimination of impeding physical and chemical factors that constrain availability of essential nutrients and water in soils,the understanding of nutrient cycling in agroecosystems,and the increase in nutrient use efficiency for sustainable crop *** soil scientists have contributed to the understanding of the cropland's role in global change,particularly to the understanding of methane and nitrous oxide emission from rice fields and the effect of elevated carbon dioxide and ozone on rice-wheat *** biology research has progressed in biological N fixation,distribution of fauna in Chinese soils,and bioremediation of polluted soils.A new generation of soil scientists has arisen in the last three *** gaps between research and application in these soil science fields are also discussed.

关键词： global change soil biology soil fertility soil resources

Application of a Digital Soil Mapping Method in Producing Soil Orders on Mountain Areas of Hong Kong Based on Legacy Soil Data

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第3期21卷 339-350页

作者： SUN Xiao-lin ZHAO Yu-Guo zhang gan-lin WU Sheng-Chun MAN Yu-Bon WONG Ming-Hung Croucher Institute for Environmental Sciences and Department of Biology Hong Kong Baptist University Hong KongSpecial Administrative Region (China) State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing210008 (China) joint Open Laboratory of Soil and Environment Institute of Soil Science Chinese Academy of Sciences and Hong KongBaptist University (China)

Based on legacy soil data from a soil survey conducted recently in the traditional manner in Hong Kong of China, a digital soil mapping method was applied to produce soil order information for mountain areas of Hong Kong. Two modeling methods （decision tree analysis and linear discriminant analysis） were used, and their applications were compared. Much more effort was put on selecting soil covariates for modeling. First, analysis of variance （ANOVA） was used to test the variance of terrain attributes between soil orders. Then, a stepwise procedure was used to select soil covariates for linear discriminant analysis, and a backward removing procedure was developed to select soil covariates for tree modeling. At the same time, ANOVA results, as well as our knowledge and experience on soil mapping, were also taken into account for selecting soil covariates for tree modeling. Two linear discriminant models and four tree models were established finally, and their prediction performances were validated using a multiple jackknifing approach. Results showed that the discriminant model built on ANOVA results performed best, followed by the discriminant model built by stepwise, the tree model built by the backward removing procedure, the tree model built according to knowledge and experience on soil mapping, and the tree model built automatically. The results highlighted the importance of selecting soil covariates in modeling for soil mapping, and suggested the usefulness of methods used in this study for selecting soil covariates. The best discriminant model was finally selected to map soil orders for this area, and validation results showed that thus produced soil order map had a high accuracy.

关键词： decision tree analysis linear discriminant analysis soil covariate selection

Mapping Soil Texture of a Plain Area Using Fuzzy-c-Means Clustering Method Based on Land Surface Diurnal Temperature Difference

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2012年第3期22卷 394-403页

作者： WANG De-Cai zhang gan-lin PAN Xian-zhang ZHAO Yu-Guo ZHAO Ming-Song WANG Gai-Fen State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) Graduate University of Chinese Academy of Sciences Beijing 100049(China)

The use of landscape covariates to variability of soil properties in similar estimate soil properties is not suitable topographic and vegetation conditions. for the areas of low relief due to the high A new method was implemented to map regional soil texture （in terms of sand, silt and clay contents） by hypothesizing that the change in the land surface diurnal temperature difference （DTD） is related to soil texture in case of a relatively homogeneous rainfall input. To examine this hypothesis, the DTDs from moderate resolution imagine spectroradiometer （MODIS） during a selected time period, i.e., after a heavy rainfall between autumn harvest and autumn sowing, were classified using fuzzy-c-means （FCM） clustering. Six classes were generated, and for each class, the sand （〉 0.05 mm）, silt （0.002-0.05 mm） and clay （〈 0.002 mm） contents at the location of maximum membership value were considered as the typical values of that class. A weighted average model was then used to digitally map soil texture. The results showed that the predicted map quite accurately reflected the regional soil variation. A validation dataset produced estimates of error for the predicted maps of sand, silt and clay contents at root mean of squared error values of 8.4%, 7.8% and 2.3%, respectively, which is satisfactory in a practical context. This study thus provided a methodology that can help improve the accuracy and efficiency of soil texture mapping in plain areas using easily available data sources.

关键词： digital soil mapping land surface temperature low relief area MODIS remote sensing

Effects of recombinant human growth hormone on growth of human gastric carcinoma xenograft model in nude mice

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第24期12卷 3810-3813页

作者： Dao-Ming Liang Jia-Yong Chen Yi zhang Ping gan Jie lin An-Bao Chen Department of Emergency Surgery of the SecondAffiliated Hospital Kunming Medical College Kunming 650101Yunnan Province China

AIM： To study effects of recombinant human growth hormone （rhGH） on growth of a human gastric carcinoma cell in vivo. METHODS： Experimental mice were divided into control group, rhGH group, oxaliplatin （L-OHP） group and rhGH＋L-OHP group. Cultured human gastric carcinoma cells BGC823 were inoculated into right axilla of nude mice and carcinoma xenograft model was established successfully. Inhibitory rate of xenograft tumor growth was estimated by measuring tumor volume; expression of proliferating cell nuclear antigen （PCNA）, Bax and Bcl-2 proteins of xenograft tumor was detected using immunohistochemical S-P method. RESULTS： Tumor growth inhibitory rate, the positive expression rate of PCNA, Bax and Bcl-2 were 49.3%, 58.2%, 65.2% and 59.2% in rhGH＋L-OHP group respectively; 46.6%, 62.5%, 59.7% and 64.7% in L-OHP group; 5.0%, 82.7%, 23.2% and 82.2% in rhGH group and 0, 77.8%, 23.5% and 80.3% in control group. There was significant difference between rhGH＋L-OHP group （or L-OHP group ） and control group or rhGH group （P 〈 0.05）, whereas there were no significant differences （P 〉 0.05） between L-OHP group and rhGH＋L-OHP group and between rhGH group and control group. CONCLUSION： rhGH does not accelerate the proliferation of human gastric cancer cell in vivo.

关键词： Human growth hormone Stomach neoplasm Nude mice

Grain Size Evidence of Multiple Origins of Red Clays in the Jinhua-Quzhou Basin, South China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2013年第5期23卷 686-695页

作者： LI Jian-Wu YE Wei zhang gan-lin ZHU Li-Dong JIANG Yong-Jian GONG Zi-Tong Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration Zhejiang A & F University State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Geography Process Lab Zhejiang Normal University Nanjing Institute of Geography and Limnology Chinese Academy of Sciences

Six typical red clay profiles were sampled from Tangxi （TX）, Langyaz （LYZ）, South Shangshanwen （SSW）, Xianqiao （XQ）, Qijian （Q J） and Huhaitang （HHT） of Jinhua-Quzhou Basin, Zhejiang Province of China to evaluate the characteristics of grain size composition, distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China. The results showed that red clays in TX, LYZ and SSW were fine and uniform, with no 〉 2 mm gravels and little 〉 63μm fraction. They had a high content of 10-50 μm fraction, so-called ＂basic dust fraction＂, and showed unimodal distributions, which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China. All these features reflected marked aeolian characteristics of the red clays in these areas. Red clays in XQ and QJ were much coarser than those in TjjX, LYZ and SSW, with high contents of 〉 63μm fraction and even containing 〉 2 mm gravels in some layers. The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess, implying they might be derived from underlying parent rocks and had some inherited properties from bedrock. Red clays in HHT had high contents of 〉 63μm fraetion and contain many 〉 2 mm gravels in each layer. The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile, revealing its alluvial or diluvial origin in HHT. The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China. It can be concluded that grain size is an effective proxy indicator for the origin of most deposits.

关键词： aeolian characteristics grain size distribution loess paleoclimate Quaternary

Impact of Long-Term Alfalfa Cropping on Soil Potassium Content and Clay Minerals in a Semi-Arid Loess Soil in China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第4期21卷 522-531页

作者： LI De-Cheng B. VELDE LI Feng-Min zhang gan-lin ZHAO Ming-Song HUANG Lai-Ming State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 (China) Laboratoire de Gdologie CNRS UMR 8538 Ecole Normal Superieure 24 rue Lhomond 75231 Paris (France) Ministry of Education Key Laboratory of Arid and Grassland'Ecology Lanzhou University Lanzhou 730000 (China)

Alfalfa cropping has been considered an efficient method of increasing soil *** nitrogen increase in root nodules is considered to be the major beneficial effect.A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil,initially containing illite and chlorite,in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping,soil potassium (K) content and soil clay *** results indicated that soil K significantly accumulated after cropping,with a peak value at about 15 years,and decreased *** accumulated K was associated with the K increase in the well-crystallized illite,which was not extracted by the traditional laboratory K extraction methods in assessing *** steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa *** biomass productivity peaked at near 9 years of culture,whereas soil K and clay minerals continued to increase until cropping for 15 *** suggested that K increased in the topsoil came from the deep root *** alfalfa continued to store K in clays even after peak production *** did not follow these trends,showing a general decline compared with the native prairie soils that had not been ***,the traditional alfalfa cropping can increase K content in the topsoil.

关键词： illite prairie soil soil fertility