Abstract:Soil classification reflects level of the overall research in pedology.An intelligent inquiry system for reference between the Genetic Soil Classification of China(GSCC)and the Chinese Soil Taxonomy(CST)based on the 1:1 000 000 soil database of China,and the techniques of WebGIS has just been established recently.The system has a Browser/Server frame-work,ArcIMS as its soil map data releasing platform,ArcSDE as its spatial database engine,and relational database SQL Server 2000 as the tool for integrated management of soil spatial and attribute data.Consists of 3 sub-modules based on national,regional(provincial),and pedon scales respectively,the system is designed to conduct reference of pedon data or between the spatial distribution features of 2 soil classification units in the 2 different classification systems.With the help of the said inquiry system,researchers interested are able to retrieve conveniently related soil classification reference information as detailed as possible.

Abstract:Soil erodibility is an important indicator to evaluate soil susceptibility to erosion,and an important parameter in soil erosion prediction.A study was carried out on the issue of soil erodibility values of different soil erosion regions in China using the data obtained from field observation of plots.A set of soil erodibility values were calculated using field data,and used to analyze feasibility of estimating erodibility of the soils in China.Results show that the soil erodibility estimation models now available from other countries could not be used directly in estimating soil erodibility in China,but there was a fine linear relationship between estimated values and measured values,though the former were obviously higher than the latter.A new method is advanced for estimating soil erodibility of the soils in China despite of difference in geographic region and availability of data.The results of the research could be directly used in prediction of soil erosion in China.

Abstract:Zoning based on spatial variability and spatial autocorrelation of soil nutritions on a field scale,is a key to variable-rate fertilization in precision agriculture.First of all,spatial variability and spatial autocorrelation of three main soil nutrients were analyzed.The variation coefficient of available P,alkalytic N and available K was 44.3% ,13.2% and 34.3% ,respectively.Available P and alkalytic N demonstrate medium spatial autocorrelation,but available K did not show any on the sampling scale.Precision of the Kriging interpolation of alkalytic N was improved by 42.8% considering anisotropy of spatial variability. Secondly,fuzzy-K-means cluster analysis of interpolated soil distribution maps was conducted to delineate management zones based on available P and alkalytic N.Fuzziness Performance Index(FPI) and Modified Partition Entropy(MPE) were employed to determine optimal zone number.The whole field was divided into four management zones.Finally,the zoning statistics showed that variation coefficient of alkalytic N and available P within a zone decreased from 13.2% on the field scale to 3.0%～5.3% , from 44.3% to 10.1%～17.3% ,respectively,while the means of the soil nutrients differed sharply between management zones.

Abstract:Rapid urbanization not only causes the decrease in acreage and type of natural soils but aslo leads to changes in soil functions which demonstrate in variation of land use.A case study of Zhengzhou City was carried out to probe evolution characteristics of soil functions during the urbanization through urban sprawl and land use variation.Results indicate that with the development of urbanization,great changes are taking place in land use structure.And as a result of the expansion of the built up area in acreage,the soil group,like Paddy soil,and the soil subgroup like salty Aquent have disappeared,and so have other 2 soil genera and 11 species and some specific soil functions as well in the past 20 years.With the steady progress of soil alienation,the soil is changing its functions mainly from production and ecological buffer to load bearing and secondly from ecological buffer to production.Such transformation of soil functions not only bring out pressure on regional agricultural production and food security,but also cause unnegligible impact on the ecological environment and human health of the region.

Abstract:To determine organic matter content(OMC)in black soil quickly,hyperspectral reflectance of black soil samples collected from the black soil areas in Heilongjiang Province was measured in laboratory,and characteristics of black soil hy-perspectral reflectance curves in the visible/near infrared bands were studied.Correlation between organic matter content and hy-perspectral reflectance was calculated,and used to ascertain main response spectrum of the organic matter in the black soil.The multivariable linear step regression analysis method was used to build hyperspectral models for prediction of organic matter content in black soil,with spectral reflectance and its derivatives(normalized and differential coefficient spectral form)as independent variables,and ln(OMC)as dependent variable.Root mean squared error(RMSE)was introduced to test the predictability and precision of the models,and coefficient of the determination(R²)was used to evaluate stability of the models.Results demonstrate:(1)620～810 nm bands are the main response spectrum of the organic matter,and the correlation coefficients are all higher than 0.8 in the spectral range,with the maximum up to 0.83 at 710 nm;(2)Normalizing the hyperspectral reflectance data of the black soil partly eliminates the noises introduced when testing different samples;(3)The coefficients of determination R² of the models are all higher than 0.9 whereas their RMSEs are all lower than 2.1,when the maximum and minimum organic matter contents are 117.8 and 6.5 mg kg^-1,so the models are quite good in stability and predictability,and can be used in fast testing of organic matter in black soil;(4)The normalized first derivate model is the optimal one.

Abstract:Environment and health of the soil are closely linked with the developments of urbanization,industrialization and agricultural intensivism.In this article,spatial distribut ions of 8 heavy metals(Cd,Cr,Cu,Ni,Hg,Pb,Zn and As)in the topsoil(0~20 cm)in Taicang city,a typical region of the Yangtze River Delta,were analyzed by mean of the geostatistical method,and heavy metal contamination of the soil evaluated comprehensively by means of Fuzzy Mathematical Models.Zn and Cu were distributed lognomally,strong in variability,while Cd,Ni,Hg,As,Cr and Pb distributed nomally,medium in variability.Apart from Cd,Cr and Pb,all the other soil heavy metals exceeded their background levels in concentration,and As ranked first in contaminat ion index and over limit rate.Compound heavy metals contamination of the soil in Taicang was quite severe,and evaluated as Grade One.The results of semivariance analysis showed that Hg and Cd were fit for the spherical model, and the others fitted for exponential model,and the distributions of the 8 heavy metals were correlated in a given spatial range. The Kriging interpolation method was applied to work out heavy metal concentration distribution maps,which indicate that heavy metal concentrations in the soils are closely related to their parent material,soil texture,and organic matter contents and the degree of industrialization,urbanization and agricultural intensivism of a city.

Abstract:Soil samples collected from an ancient paddy soil profile(BP 6 000 a)were analyzed with HPLC for 15 polycyclic aromatic hydrocarbons(PAHs)in order to determine their contents and distribution patterns.The total PAHs in various soil layers varied between 25.9 and 202.9μg kg^-1,with the highest observed in the surface horizon.Nap,Phe,Fla and Pyr were the four major compounds in a decreasing order of Nap>Phe>Fla>Pyr in terms of abundance.PAHs of 4 or more rings accounted for 51.8% of the total.In deeper layers,total PAHs decreased sharply,and the number of detectable compounds also decreased.Moreover,2-and 3-ring PAHs became the dominant compounds in these layers,but 4-or more-ring PAHs still formed a large portion of the PAHs in the ancient paddy soil.The results of the principal component analysis and cluster analysis indicated that Chr,BkF,BaA,IcP,BbF,Pyr,BaP,DaA and Fla were products of human activities,Flu and Phe were formed in biological process under reducing conditions,while Nap,BgP and Ant might result from the joint effect of human activities and biological process.

Abstract:The complexes of dissolved organic matter(DOM)and polycyclic aromatic hydrocarbons(PAHs)play an important role in environmental behaviors of PAHs.Interactions between DOM and PAHs are involved in forming complexes of DOM and PAHs.However,besides partitioning and hydrophobic effects,little is known of the interact ions between DOM and PAHs. In the paper,the interactions of DOMs derived from paddy soil,pig manure and sewage sludge respectively with phenanthrene (Phe)and pyrene(Pyr)were investigated with Fourier transform infrared(FT-IR)spectroscopy.With all the DOMs tested,asorption peaks were found in the bands of 4 000~3 000 cm^-1,2 969~2 900 cm^-1,1 700~1 375 cm^-1,1 300~1 000 cm^-1,and 900~600 cm^-1,suggesting that DOM contained O-H(hydrogen bonded alcohols,phenols and carboxylic acids),NH(amines),aromatic ring,C-O(polysacchrides,carboxyl),and-CH₂ function groups.Comparison of the FT-IR spectra of DOM and DOM-Phe/Pyr revealed that absorption peaks of DOM-Phe/Pyr in the bands of 4 000~3 000 cm^-1,1 700~1 375 cm^-1,and 900~600 cm^-1 shifted to longer wavelengths,indicating that there existed NH-π and π-π interact ions in the formation of complexes of PAHs and DOM.

Abstract:Concentrations of rare earth elements(REEs)in soil and plant samples collected from different areas,West Guangdong were determined with the ICP-MS method to study geochemical characteristics of these elements.Results show that no big difference was found within a soil plant system in REEs distribution pattern,but they were detected between soils derived from different parent materials,with the soils derived from granite being the highest in REE concentration.Within a soil profile, REE concentrations were higher in B and C horizons than in A horizon.Differentiation between light REEs and heavy REEs occurred displaying some extent of negative Eu anomaly changes,while Ce showed posit ive anomaly in all soil layers.Plants different in genera growing in the same sampling site were quite similar in REE distribution pattern,but plant of the same genera growing in soils derived from different parent materials differed in REE distribut ion pattern.Obviously,REE distribution in plants are influenced by the soils they grow in and also displays their individual biogeochemical characteristics.Biological absorpt ion coefficients indicate that plants vary sharply in REE absorption capacity.REEs are obviously fractionated when they are transported and migrated from soils to plants,revealing that heavy REEs are relatively sparse.

Abstract:An experiment was carried out in the greenhouse using a three-compartment rhizobox system to study effects of inoculation of arbuscular mycorrhizal fungi Glomus etunicatum,Glomus intraradices and Glomus mosseae on Festuca rubra and Agrostis hugoniana,and soil environment.Results indicate that inoculation had significant effects on AM fungi infection of the plants and plant growth,increasing dry matter and P contents of both ground parts and roots and phosphorus absorption rate of the plants,improving microbial flora in the rhizaphere and water stability of soil aggregates.The mycorrhizal effects was better on Agrostis hugoniana plants than on Festuca rubra,and Treatment Festuca rubra+Glomus mossene and Agrostis hugoniana+ Glomus intraradices were better than the others in each group.The root chamber more microorganisms of various kinds than the other two,but the mycorrhizal chamber had a higher ratio of actinomycetes,especially of bacteria and fungi,which meant the difference between rhizosphere and mycorrhizosphere became small.All treatments on inoculation rate and hyphal density accorded with each other.The higher the inoculation rate,the higher the hyphal desity.Mycorrhizal hyphal contribution to the formation of water-stable soil aggregates of 5～2 mm was 100% within the distance of 4～6 cm from the root surface,however not within the distance of 0～2 or 2～4 cm.The hyphai also had significant effect on water-stable soil aggregates(more than 70%) within the distance of 2～1 mm,but significantly less than within distance of 0～2 and 4～6 cm,and did not show the rising effect with the hyphal density.Effect of Arbuscular mycorrhiza on steppe plants and infection rate of steppe plants varied with species of the mycorrhiza and plants.The effect on Agrostis hugoniana was greater than on Festuca rubra in all inoculation treatments,and the effect of the combinations of Festuca rubra+Glomus mosseae and Agrostis hugoniana+Glomus intraradices were more significant than others.

Abstract:Under field experiment condition,effects of foliar application of Na₂SeO₃ on concentration and form of Se,and protein-bound Se in grains of Longqing 4,86 You 8 and Bing 9 652 varieties of rice were studied in South Jiangsu.Results show that foliar application of Na₂SeO₃ at a rate of Se 10 g hm^-2 could raise significantly Se content in rice up to 255.3～586.5 μg kg^-1,which was 7.9～11.0 times higher than that in CK.Moreover,foliar applicationof Na₂SeO₃ did not show any negative effect on rice yield.Most Se in rice grains was organic Se,occupying over 87.72%～90.98% of total selenium,and protein-bound Se accounted for 43.07%～51.65% of the organic selenium and 38.04%～48.98% of total selenium.Application of Na₂SeO₃ did not affect much distribution of protein.The spectral bands of the grains(Longqing 4 and Bing 9 652)with or with-out Se application were more or less the same,except for some new protein bands between 14～20 kDa,suggesting that Se application might increase formation of some small molecular proteins.

Abstract:Aging and bioavailability of DDTs in paddy soil were investigated in the lab under simulated conditions.Results indicate that aging phenomena of DDTs existed in soil.Extractable DDTs decreased as the time elapsed.Its aging rate was rather high at the initial stage,and then slowed down in the rest of the time.During the first 30 days,o,p'2DDT,p,p'2DDT,o,p'-DDE,p,p'2DDE and p,p'2DDD dropped by 53.5% ,52.1% ,31.4% ,36.0% and 38.3% ,respectively due to high aging rate.DDTs,bioaccumulated in earthworm displayed the same rule as aging,that is,the contents of DDTs in earthworm decreased as the incubation time extended and so did.Bioconcentration factors(BCF)of DDTs in earthworm show a decreasing order of BCF_p,p'2DDE>BCF_p,p'2DDD>BCF_o,p'2DDE>BCF_o,p'2DDT>BCF_p,p'2DDT.Though the extractable DDTs decreased with aging, they still accumulated in earthworms through bioconcentration,and biomagnified through the food chain,thus posing potential environmental risk.

Abstract:Effects of pH and organic matter on Cu adsorption in a sandy loam near orchard were studied.Results showed that i)the isotherm of Cu adsorption could be described by Freundlich equation and ii)statically adsorbed Cu was easier to get desorbed than specifically adsorbed one.Kinetic experiments demonstrated that up to 60% of the Cu adsorption occurred within the initial 4 h,and equilibrium was reached after 8 h,while up to 80% of the Cu desorption did within the initial 30 min, and equilibrium was reached after 2 h.Cu adsorption rate was lower at low pH than at higher pH,which was a result of competitive adsorption of H⁺,and logK_d showed a positive linear correlation with pH while in neutral and alkali condition,the effect of pH on adsorption could be neglected.The removal of organic matter from the soil reduced the distribution coefficient K_d 10 times as compared to the natural soil.

Abstract:Adsorption of Prochloraz and its major metabolites,BTS44595,BTS44596 and BTS45186,in six types of paddy soil were studied with the batch equilibrium method.Results show that the paddy soils adsorbed Prochloraz and its metabolites by physical means,and the adsorption process could be represented with the Freudlich isotherm equation.Absorbing capacity of the paddy soils was higher for Prochloraz than for its metabolites,and there was no visible distinction in adsorption amount between the three metabolites.Adsorption of Prochloraz by the paddy soils were positively correlated with organic matter content,cation exchange capacity and clay content,while adsorptions of the three metabolites were restricted by pH values of the paddy soils, suggesting that metabolism of Prochloraz could change its adsorption behavior and mechanism in the paddy soils.Therefore,adequate attention should be paid to that when Prochloraz was applied to the paddy soil.

Abstract:Effects of earthworms on soil nitrogen mineralization were studied in laboratory.Soil samples were destructively collected periodically on D2,D6,D13,D20,D27,D41,and D55 after incubation.Four treatments were designed:(1)soil without earthworms or straw-control treatment(S);(2)soil only with earthworms(E);(3)soil only with straw(O);and (4)soilwith earthworms and straw(OE).Results indicated that throughout the entire incubation period,only Treatment Ewas significantly higher than Treatment S(p<0.05)in both NH₄⁺-N and NO₃^--N,by about 0.54～5.71 and 0.04～2.01 times separately.Compared with Treatment O,Treatment OE was much higher(p<0.05)in content of soil NH₄⁺-N,by about 0.42～7.26 times.but was more or less similar(p>0.05)in content of soil NO₃^--N.Whether the straw was used or not,Treatments E and OE were significantly higher,or 1.93 and 2.36 times higher than Treatments S and O in content of mineral nitrogen (NH₄⁺-N+NO₃^--N),respectively,after 55 days of incubation.The soil nitrogen mineralization rate and cumulative nitrogen mineralization rate in Treatment E increased significantly(p<0.05)over Treatment S;In Treatments O and OE,whether earthworms were introduced or not,the cumulative nitrogen mineralization rates were below zero,represented as net immobilization of soil mineral nitrogen,and change in nitrogen mineralization rate showed net immobilization in the early phase,and certain mineralization in the late phase.The content of total nitrogen in Treatment E was significantly higher(p<0.05)than in Treatment S in all the incubation phases except for in the first 2 days of incubation and at the end of the experiment,it was about 6.55% higher.Besides that,significant positive correlation(p<0.01)was observed between soil total nitrogen content and decrement of earthworms in fresh weight.When the loss of earthworms in fresh weight was converted into the loss of nitrogen through earthworms with the simple liner equation,it was found that the nitrogen excreted by earthworms accounted for about 42%～100% of the increment of soil total nitrogen.

Abstract:Based on the data obtained from 9 long-term field experiments(1986～1999)in Hunan Province,difference in rice yield and soil fertility between paddy fields under different fertilization patterns was analyzed,with emphasis on effect of ratio of organic manure/chemical fertilizer on rice yield and soil fertility under the same N input condition.Results show that:based on averages over 13 years,Treatment NPK was 115.43% (early rice)and 68.20% (late rice),Treatment L-OM,128.45% (early rice)and 79.26% (late rice),and Treatment H-OM,122.87% (early rice)and 78.66% (late rice)higher than CK in yield.Mineral nutrients supply in the rice growth period is the key factor that leads to difference in rice production between different treatments.Compared with CK,Treatment NPK was obviously higher in soil nutrient content,indicating that chemical fertilizer does not only supply mineral nutrients to the crop,but also improve soil fertility.Treatment H-OM was higher than Treatment L-OM in soil nutrient content,suggesting that a high proportion of organic manure in fertilization has better effect on improvement of soil fertility.During the early monitoring period,the difference between Treatments L-OM and NPK in yield was widening, and then narrowing in the last few years.The difference between Treatment L-OM and H-OM always showed a narrowing trend, especially for late rice.All these suggest that yield difference varying with organic-inorganic fertilizer ratio is a temporary phenomenon and with the time going by and improvement of soil fertility,this difference will become narrower and narrower and even disappear.

Abstract:The objective of this study was to predict the potential influence of sulfur-coating material left in the soil from using sulfur-coated urea(SCU)on agricultural ecosystem.In order to find effects of sulfur in the coating of SCU on cole growth and soil chemical properties,a pot experiment,which was designed to have 6 treatments,was conducted.Results of the experiment indicated that both the coating and sulfur applied could significantly enhance activity of Fe,Mn and Zn in the soil,and affect contents of water-soluble K⁺,Na⁺,Ca²⁺,Mg²⁺,SO₄^2-,HCO₃^-,and Cl^- in the soil.Besides,they tipped the original acid-base balance and redox balance of the soil,which was represented as increase in soil exchangeable acid and exchangeable Al,but decrease in soil pH,and contents of reductive material and active reductive material.At the same time they were shown to be able to promote cole growth and uptake of N,P,K and S.Application of sulfur could still have some crop response in yield in SCU treatments.The short-term impact of sulfur-coating on soil chemical properties was weaker than that of sulfur.

Abstract:Populations and distribution of soil nitrogen bacteria groups(ammonifying bacteria,nitrobacteria,free nitrogen fixing bacteria and denitrobacteria)in alpine steppe of different disturbed habitats in Tianzhu were investigated and analyzed with the plate count and MPN methods.Results show 1)Populations of soil nitrogen bacteria groups varied greatly with soil depth. They were much greater(1.44 to 7.32 times)in 0～20 cm soil layer than in 20～40 cm one;and they also varied sharply from group to group,forming a decreasing order of ammonifying bacteria>free azotobacteria>denitrobacteria>nitrobacteria; 2)They differed sharply from habitat to habitat in the range of 1.27～9.29 times,and moreover the effect of habitat on population of nitrobacteria was much stronger than on those of denitrobacteria and ammonifying bacteria;3)The total population of the nitrogen bacteria groups was the highest in the annual artificial grassland,which was followed by perennial grassland,fenced grassland,rodent hill and un-fenced grassland in a decreasing order;and 4)Regardless of difference in habitat,spatial distribution and groups,the populations of soil nitrogen bacteria groups showed a general saddle-shaped tend,i.e.within the 0～20 cm soil layer,they were low in J uly,rose up the peak in August and declined in September,and within the 20～40 cm soil layer, they show the same but smaller in amplitude.

Abstract:An experiment was carried out of persistent activating effect of citric acid on phosphorus in red soil.Results show that amount of the phosphorus activated decreased gradually with the increase in frequency of extraction,but never down to nil,and the activation intensified with the increasing citric acid concentration.Fractionations of inorganic phosphorus in the soil samples before and after the extraction show that phosphorus was activated by citric acid mostly from the fractions of Al-P,Fe-P and Ca-P,and some from the fraction of organic phosphorus,and that citric acid accelerated formation and accumulation of Oc-P in red soil.Effect of concentration of citric acid on activattion of phosphorus from Al-P,Fe-P and Ca-P was very clear.When the concentration of citric acid was 5 mmol L^-1 and 10 mmol L^-1,the fractions were in the order of Ca-P>Al-P>Fe-P in terms of amount of phosphorus activated,but when it was 100 mmol L^-1,the order was:Fe-P>Al-P>Ca-P.

Abstract:Diversity and its spatial distribution of bacteria in 0～5 cm,5～10 cm and 10～15 cm depths of non-tillage paddy fields were studied based on the molecular method of ARDRA(amplified ribosomal DNA restriction analysis).Results indicted that in different soil layers of the paddy field,bacteria were very high in species diversity,which,however,varied from layer to layer due to differences in soil moisture,soil depth,soil temperature,daylight and some other factors.Bacteria in the surface layer were the highest in species diversity,but without a dominant genotype.They were relatively low in species diversity in the 10～15 cm soil layer,but they did have some dominant genotype.Bacteria communities in different soil layers showed little similarity.The Jaccard index was 20.65% between the bacterial clones libraries of the 0～5 cm and 5～10 cm soil layers; only 8.31% between those of the 0～5 cm and 10～15 cm soil layers and 38.75% between those of the 5～10 cm and 10～15 cm soil layers,indicating complexity of the structures of soil bacteria communities and spatial segregation in the soil.

Abstract:To study on autotrophic removal of nitrogen from wastewater containing a high concentration of NH₃-N,a strain of Pseudomonas fluorescens dN13 was isolated,by means of incubation in Skerman's medium for Nitrosomona,from the sequence batch reactor system(SBR)of a wastewater treatment plant in Nanjing.Under aerobic condition,this strain could oxidize NH₃-N into NO₂^--N and grow without organic carbon source;and reduce NO₂^--N and NO₃^--N into NH₃-N with organic carbon source and adequate concentration of NO₂^--N and NO₃^--N,while under anaerobic condition,strain dN13 could still reduce NO₂^--N and NO₃^--N into NH₃-N with sodium acetate as the sole carbon source.In the cells of strain dN13 with such multi-paths of nitrogen metabolism,coupling of nitrification and denitrification is feasible.

Abstract:The aqueous two-phase part itioning(A2PP)technique,considered as a useful tool to separate and purify cells, virus,macromolecule,has found extensive application in biochemistry,cytobiology and other relevant fields.However,few reports are so far available on its applicat ion in the field of soil microbiology.This experiment was designed to study components of microbes in red soils with the PEG/Dextran A2PP technique.Results show that soil bacteria were well dispersed after the Dowex resin,sodium cholate,glass beads and soils were mixed into suspension,which was then shaken for 2h at the temperature of 4 e.The separation rate of bacteria ranged between 0.41~0.60 and varied with parent material in the order of sandstone> granite>Q₂ deposits.The experiments demonstrated that A2PP could separate and purify soil bacteria quite well.With the two-phase technique,about 63%~78% of the bacteria in the soil samples were separated and stored in the PEG phase.With the fluorescence microscope technique,most soil bacteria were closely tied with soil clays and organic matter,whereas with the A2PP technique purer bacteria could be obtained.The bacteria extraction rate was in the range of 0.31~0.48,and varied with parent material in the same order of sandstone>granite>Q₂ deposits as was with the separation rate.For the six red soil samples examined,micrococcus and microbacilli were dominant in terms of forms of soil bacteria.

Abstract:A general review of recent development and application of the technology of remote-sensing in monitoring soil moisture was done with emphasis on introducing the relatively mature and extensively used feature space method and microwave remote-sensing method based on visible light and thermal infrared bands.It also analyzed advantages and disadvantages of various remote-sensing methods in monitoring soil moisture,pointed out shortages with the remote-sensing methods,predicted directions of future development and foretold prospects of the technology of using remote-sensing to monitor soil moisture monitoring.

Abstract:土壤质量动态变化研究是以土壤质量评价为基础,通过土壤质量指数的时空变化来反映。因评价实体、目标、指标体系的不同,评价模式(方法)也存在差异。由于涉及多个评价指标,所以属于高维数据处理问题。针对传统评价方法存在指标权重确定没有统一的理论和计算方法的不足,本文提出用基于实码加速遗传算法(Real coding based accelerating genetic algo-rithm,简称RAGA)的投影寻踪等级评价(Projection pur-suit grade evaluation,简称PPE)模型^[1~7]。

Abstract:贵州位于全球最大的喀斯特生态系统—中国西南喀斯特生态系统的中心,由于受到亚热带季风气候的冲击和人类不合理社会经济活动的破坏,其喀斯特生态系统已出现不同程度的石漠化,尤以乌江流域最为严重。现已认识到石漠化是一种与脆弱生态地质背景和人类活动相关联的土地退化过程,而土壤退化是土地退化的核心部分^[1,2]。在土壤侵蚀与退化及全球碳循环的过程中,作为土壤重要组成部分和代表一个主要碳库的土壤有机质在生态系统中扮演了一个十分重要的角色^[3],开展对喀斯特地区不同土壤有机质剖面分布及稳定碳同位素组成的研究,将有利于提高对流域土壤侵蚀与退化过程中有机质的生物地球化学循环的认识。

Abstract:目前络合诱导植物修复作为一种强化植物吸收重金属的修复技术备受关注^[1]。对于一些难移动的污染元素(如Pb、Cu等),添加化学试剂能显著增加土壤溶液中的重金属浓度,从而促进植物对重金属的吸收与富集^[2~5]。然而,研究者也发现大量被络合活化后的重金属具有较强的水溶性,极易通过淋溶渗漏而造成对地下水的二次污染,对周围环境构成严重的生态风险^[5~8]。但到目前为止,还没有切实可行的办法来有效控制络合诱导植物修复过程中的重金属迁移风险。

Abstract:苜蓿-作物轮作是我国西北半干旱区常见的耕作方式。由于苜蓿的强蒸散特征^[1],苜蓿生长多年后常导致土壤水分匮缺,形成土壤干层^[2,3],对后茬作物的生长产生不利影响。根据当地轮作习惯,苜蓿种植后通常种植一种浅根系的作物草谷子(Setaria italica Beauv)来恢复土壤水分并获取饲料,但是这种耕种模式对土壤水分恢复的效果如何还不得知,苜蓿草地轮作为农田后的土壤水分恢复过程需要加以明晰。由于苜蓿的生物固氮作用,由农田轮作为苜蓿草地一般不会存在土壤肥力障碍,并会不断提高土壤肥力水平^[4]。

Abstract:随着旅游业成为世界第一大产业,由其对生态环境所造成的破坏就越来越严重,也引起了人们的高度重视,有关旅游对生态环境的影响研究已成为当今环境与旅游的重点之一。微生物是生物圈的三大成员之一,也是土壤圈、水圈的活跃成员。土壤微生物是土壤的重要组成部分,是土壤物质转化的重要参与者,同时又是一个重要而丰富的基因库,是生物多样性与生态平衡的一个重要方面,土壤微生物的平衡发展也是预防植物病害发生的基础^[1,2]。由于有机质转化所需能量的90%以上来自微生物的分解作用,因此,土壤微生物活度总量是土壤—植物体系中有机质转化的较好指标^[3]。土壤质地、肥力及植被等都直接影响着土壤微生物的活性及其多样性^[4,5]。