Abstract:Mechanism of distribution of soil organic matter(SOM)with depth was studied based on SOM content,SOM ¹⁴C,SOM ¹³C,clay content and sporopollen composition of two soil profiles at the forest vegetation zone and shrub-meadow zone in the Dinghushan Biosphere Reserve.Results indicated that distribution of SOM with depth was related to the evolution of soil profiles.With the depth SOM sources decreased but SOM loss increased due to SOM decomposition during evolution of the soil profiles and SOM content decreased gradually while SOM ¹⁴C apparent age increased.Obvious correlationship was observed between variation of the SOM ¹³C value with the depth and that of the SOM contents with the depth.All these were the result of regular decomposition of SOM in different replacement periods during the development of the soil profiles.Vertical distribution of clay reflected the characteristics of pedological illuviation of the soil profiles,indicating that the soil profiles had undergone a long period of pedogenic weathering.The above characteristics of the soil profiles are the results of continuous deposition and soil formation during evolution of the soil profiles,suggesting a significant restraining effect on distribution of SOM with the depth.

Abstract:The effects of maize growth and N-application(N 150 mg kg^-1 and 300 mg kg^-1)on soil respiration were investigated in pot experiment.The results showed that in the maize-planted soil,the soil respiration rate ranged from C 19.6 to 762.1 mg m^-2h^-1,but in the bare soil,it was in the range from C 4.3 to 36 mg m^-2h^-1.Soil respiration rate was the lowest at the seedling stage and 73% of the soil respiration occurred at the elongating-booting stage and ripening stage.The contribution of maize rhizosphere respiration to soil respiration in each stage varied from 58% to 98% and was the lowest at the seedling stage.In the bare soil,N-application had no significant effect on soil respiration,whereas in the maize-planted soil,the soil respiration was 28% higher in the treatment of high N-application rate than in the treatment of low N-application rate during the whole maize-growing period.The significant difference between the two treatments only occurred in the metaphase and anaphase of maize growth.There was no significant correlation between soil respiration rate and temperature in the maize-planted soil,but in the bare soil,soil respiration rate was correlated exponentially to the temperature of the air,soil surface and at 5 cm depth significantly,and its correlativity was higher in the treatment of high N-application rate than in the treatment of low N-application rate.In conclusion,maize growth and soil N-application rate influenced not only the rate and intensity of soil respiration,but also the distribution of soil respiration in each developing stage of maize and the relationship between soil respiration rate and temperature.

Abstract:Using fly ash as a tracer overcomes the limitation that the ¹³⁷Cs tracer method has in explaining the processes of soil redistribution prior to a nuclear explosion in the atmosphere.In this study fly ash was used as a time marker to study spatial and temporal characterist ics of the redistribution of soil organic carbon(SOC)in Black soil,Northeast China.Attempts were made to build up a methodology to determine thickness of accumulated layers and the soils underneath using fly ash.Results showed that the method was capable of est imating relative age of the accumulated materials.The surface of the buried soil determined by the fly ash technology was in consistency with that obtained with the method based on variation of SOC concentration with the depth in profiles.The results also indicated that redistribution of soils in the study area occurred prior to the use of steam locomotive.Among the studying geomorphic positions,at the shoulder-slope erosion was the strongest and the content of SOC was the lowest.There was no obvious erosion at the summit because of small slope gradient.Redeposition also took place at backslope,foot-slope and toe slope.The rate of soil deposition ranged between 1.01~5.56 mm a^-1.The study also found that the content of SOC in buried surface layers was higher than that in the plowed layer,which indicated that there was much organic carbon sequestered below the plowed layer.The effects of soil transport and burial need to be considered in assessing agricultural soils as carbon resource or sink of atmospheric CO₂.

Abstract:Water retention,water flow and solute transport in soil,to some extent,depend on geometric characteristics of the soil pore,which can be accurately ident ified with the digital image analysis method.In this art icle,pore fractal dimensions and multiple pore outline fractal dimensions of some soil sample images are calculated with the area method and circumference method,separately.And the relationship between those fractal dimensions and soil texture is discussed.The results show that obvious fractal features can be found only of soil pore spaces of a certain scale.The finer the soil texture(or the higher the clay content),the higher the value of the fractal dimension.Comparatively,the pore fractal dimension calculated with the area method is more sensitive to soil texture than with the circumference method.

Abstract:The Dexing Copper Mine is a super-scaled copper mine in China.Release of large amounts of tailings is one of its main environmental problems.The tailings are stored in several tailing pools and No.1 tailing pool has in storage about 2.15×10⁷ m³ of tailings covering an area of 210 hm² after running out of service in 1986.Beginning from the late 1990s,a series of experiments were performed on revegetation of a part of the mine tailing pool,dam slope,30 hm² in acreage,which was covered with guest soil.Changes in basic agrochemical properties of the soil and extractable heavy metals(by 0.05 mol L^-1 HCl)under different vegetations,e.g.upland rice(Oryza Linn.),peanut(Arachis Linn.),vetiver(Vetiveria zizanioides Nash)and slash pine(Pinuselliottii Engelm.)were determined during the experiment period of 3-4 years.The results indicated that the soil was very low in nutrients N,P and K and in nutrient loading capacity as well.It is therefore necessary to build up soil fertility continuously.Soil pH did not show much change,soil OM increased significantly but soil NH₄⁺-N decreased with the time.Though soil available P and K obviously increased,they were still at a low level.Soil heavy metal pollution,especially with Cu,was very serious.Moreover,Cu,Pb,Zn,and Cd accumulated in the plants and exceeded the criteria of the food hygiene standards in some food crops and vegetables.The results indicate that for revegetation of the tailing pool,it is not advisable to grow food crops lest contamination should be spread through food chain.

Abstract:A large number of deserted copper mine tailings dumps of different age exist in Tongling,East China,covering a large area of land.In order to understand effect of natural plant communities on enzyme activities in the soil,six dumps different in age were investigated.The results show that the plant communities naturally colonizing on the wastelands markedly increased enzyme activities(urase,arylsulfatase,alkaline phosphatase and dehydrogenase)in the upper layer of the tailings(0~5 cm).But the effect varied with the type of the plant communities.Enzyme activities in tailings under the Hippochaete ramosissmium-Zoysia sinica community and Impreta cylindraca community were higher than under the Cynodon dactylon community and Zoysia sinica community.Of the 4 soil enzymes studied,alkaline phosphatase and dehydrogenase were higher than urase and arylsulfatase in activity.Data analysis indicates that there was a significantly positive correlation between enzyme activities and chemical propert ies(including humus,total nitrogen,available phosphorus,available potassium and electrical conductivity), but a significantly negative correlation between pH values of the tailings and act ivities of arylsulfatase and dehydrogenase.The surface layer of tailings heavily oxidized exhibited extreme infertility and extremely low activities of soil enzymes.

Abstract:Sustainable management of urban soils to minimize their potential impact on the environment requires an understanding of factors influencing mobility of heavy metals in the soils.The objective of this study was to analyze concentrations, forms and acid solubilities of heavy metals in the soils from fifty residential sites in Hangzhou City.In addition,Pb,Cu,Zn, and Cd adsorption-desorption behavior,relationship between release of heavy metals and pH,and acid buffer capacity of the soils were also studied.The soils in the residential sites had been anthropogenically contaminated by heavy metals to a different extent.Except for Cr and Mo,however,concentrations of these heavy metals in the soils were found lower than those in the soils in commercial districts.Cd,Co,Cr and Ni were mainly in stable residual forms,while Cu,Pb,Zn and Mn were mostly in extractable forms.Generally the soils in the residential sites had a high capacity to adsorb heavy metals,so stably that they were not liable to get displaced by neutral salts.The capacity however,decreased with the decrease in pH,and release of heavy metals from the soils increased rapidly when soil pH went down below 4.0～6.0.The acid buffer capacity of the soils varied greatly and was mainly controlled by soil CaCO₃ content.The heavy metals in soils with a high acid buffer capacity were low in solubility. Since the soils in the residential sites contained higher CaCO₃ brought in by construction materials,they often had a high acid buffer capacity and thus enhanced stability of the heavy metals in the soils.Our data indicated that heavy metals of the soils from residential sites in Hangzhou City did not pose significant hazard to the environment in normal conditions.

Abstract:Mercury flux at the air-and-soil interface in Guiyang and its suburbs was measured with the dynamic flux chamber method.At the same time,meteorological parameters such as air temperature,soil temperature,humidity,solar radiation,wind direction and wind speed were recorded with a multi-function mini-weather station.The results at these four sites, show that concentrations of mercury in the air were significantly elevated over the global background values(1.5~2.0 ng m^-3), which indicates that the air of Guiyang and its suburbs was polluted to a varying extent due to anthropogenic atmospheric mercury emissions.The results also illustrate that Hg flux was significantly correlated with both solar radiation and soil temperature.

Abstract:Chromium usually existed in soil in two valences,Cr(Ⅵ)and Cr(Ⅲ),which are different in charges.Previous studies showed that Cr electrochemical processes in soil were complex due to its varied valences and strong oxidation reduction reactions.This paper investigated Cr electrokinetic processes in Yellow brown soil as affected by hydrogen peroxide.The experiment was performed with a lab made electrokinetic setup,made up of electric power supply,a soil column,a four channel peristaltic pump,two electrode chambers,a pH controller and two solution reservoirs.The results show that Cr(Ⅵ)concentration in the soil after 564 h electrokinetic treatment significantly decreased as compared with the initial value(C₀=396 mg kg^-1).The presence of H₂O₂,as a model reductant of soil,caused Cr(Ⅵ)reduction to stable Cr(Ⅲ).Effect of H₂O₂ on electrical current was not obvious,but it significantly decreased the electroosmotic flow rate,suggesting its influence on soil surface structures and soil solution physical and chemical properties.All 4 treatments resulted in removal of over 85% Cr(Ⅵ) from soil.However,the total removal rate of Cr in the presence of H₂O₂ decreased.The maximum removal rate of total Cr and Cr (Ⅵ) was obtained,being 39.6% and 91.6% respectively during the electrokinet ic treatments.

Abstract:Nonequivalent exchange and nonelectrostatic adsorption also appeared during exchange-adsorption between Ca-/K-solid phase and aluminium/manganousions,while exchange reaction for calcium and potassiumion pair was electrostatic adsorption.Amount of nonelectorstatic adsorption was controlled both by field intensity of solid surface and hytrolysis nature of ion and its valence number,in which aluminium had the largest value in laterite.The relation between k,K,1/n and ΔF was comprehensively explained from enengy concept,exchange adrorption of aluminium with the largest k,K and the smallest 1/n, hence with negative ΔF.The mechanism for basicions to aluminium transformation in red soil,namely acidification,which was an irreversible and continuously spontaneous proccesses under natural conditions,was proved in thermodynamics.

Abstract:Effects of calcium biphosphate(MAP)and potassium chloride(KCl)on transformation of ammonium sulfate (AS)in the paddy soil were investigated through laboratory incubation.The results show that MAP can only affect transformation of AS to a limited extent.The increase in nitrification in the soil without ammonium applied and decrease in nitrification in the soil with application of MAP might be associated with change in soil pH.The application of KCl significantly affected transformation of AS in the paddy soil,mainly in the following aspects:(1)The increase in water soluble ammonium(WSA)and decrease in exchangeable ammonium(EA)as a result of the addition of KCl at the initial stage of incubation were attributed to replacement of K⁺ and NH₄⁺ in the soil,but the increase of both WSA and EA at a later stage was related to the inhibitive effect of K on nitrification.(2)The presence of potassium significantly suppressed release of fixed ammonium during incubation or extraction of the soil with NaCl.The different effects of K on WSA in the fresh soil and ai-rdried soil were also attributed to K inhibit ing ammonium release during air-drying course.(3)When potassium and ammonium were applied together into the soil,potassium increased ammonium fixation in the soil.(4)Nitrification of ammonium in the paddy soil was significantly suppressed by KCl, which might not result directly from K inhibiting release of ammonium under the controlled condition.Application of potassium alone might decrease availability of inorganic nitrogen in the paddy soil without N application.Thus it can be inferred that combined application of potassium and ammonium will not only reduce leaching and denitrification of nitrite,but also increase buffer capacity of soil ammonium.The results indicate that the interactions between NH₄⁺ and K⁺ in the soil may be one of the reasons why combined application of potassium with nitrogen fert ilizers could increase efficiency of nitrogen fertilizer in production.

Abstract:A field plot experiment with five P application rates and 4 replications each was conducted on Percogenic paddy soil in the Taihu Lake Region(TLR)in the years of 2002 and 2003 to monitor the concentration and fractionation of dissolved phosphorus(DP)in leachate at different depth.Results indicate that fertilization increases the concentration of DP in leachate at 30cm in depth at the initial stage,has a little effect in leachate at 60cm,and no effect in leachate at 90cm.However, the concentrations of dissolved P in leachates at 60 and 90 cm were higher than 0.02 mg L^-1,which suggests that the leaching may contribute to water eutrophication.Dissolved organic phosphorus(DOP)dominated in the leachate at 90 cm during the entire rice growing season accounting for 56% ~100% of the dissolved phosphorus(DP)in all the treatments except the control on Jun 13.The concentration of DOP in the leachate did not increase along with the P application rates in this experiment,indicating that DOP comes mainly from dissolution of the existing soil organic P by leachate and/or from organic manure applied or with irrigation water.

Abstract:On the basis of the second national soil survey in 1980,all the cultivated lands in Quzhou County,Hebei Province were surveyed and analyzed,and with the aid of GPS and GIS technology in October 2002.The results indicate that with development of the program of comprehensive management of salt-affected soils,improvement in quantity and quality of extraneous input,and readjustment of cropping arrangement,great spatio-temporal variation of soils nutrients in the salt-affected soils of the land amelioration zone.Temporally,soil organic matter and rapidly available P have increased from 8.4 g kg^-1,and 5.45 mg kg^-1 to 13.89 g kg^-1 and,23 mg kg^-1 respectively;total nitrogen up to 0.937 g kg^-1;and rapidly available K from 34~ 285 mg kg^-1 to 67~191 mg kg^-1.Spatially,the distribution of soil nutrients shows a close relationship with geochemistry process of the nutrients,crops distribution,and cultivation pract ices.It is represented mainly in that soil organic matter,total nitrogen,and rapidly available P increased in content with the degree of intensification of the farming,and the application rate of extraneous input,and that the content of rapidly available K varies with the intensification of farming instead of originally with the geochemical process.

Abstract:Based on the orthogonal test design,a field experiment was carried out in mudflat along the coast of Laizhou, Shandong Province to study coupling effect of salt and fertilizer application on Helianthus tuberosus irrigated with seawater different in concentration.The results show:(1)When the fertilization rate remained the same,no significant difference in yield of tuber and aerial parts of the plant between Treatment W₂(25% seawater)and Treatment W₁(fresh water).Their yields,however, significantly declined by 32% and 76% and by 25% and 60% respectively when the irrigation water contained higher percentage of seawater,50% in Treatment W₃ and 75% in Treatment W₄.In the trials of N fertilization,comparison of Treatment N₃(150 kg hm^-2)with Treatment N₁(0 kg hm^-2)showed that the yields of the former were 77% and 37% higher than that of the latter,respectively,and the yields in Treatment N₄(225 kg hm^-2)were lower than in Treatment N₃,but higher than in Treatment N₂(75 kg hm^-2).In the tests on P fertilization,the yields of tuber and aerial parts were respectively higher 97% and 39% in Treatment P₃(60 kg hm^-2)than in Treatment P₁(0 kg hm^-2),and they were lower 19% and 11% lower,respectively,in Treatment P₄(90 kg hm^-2)than in Treatment P₃(60 kg hm^-2).(2)In all seawater treatments the Helianthus tuberosus.main stem got longer and thicker with the increase in N and P.(3)Analysis of the interactions of seawater,N and P showed that Treatments W₂N₃ and W₂P₃ were the opt imal combinations.The main factor that affected the yields was seawater,and flowed by fertilizers of N and P.And the best combination was W₂N₃P₃.

Abstract:The soil column leaching method was adopted to study effects of application of desulphurisation products on chemical indices(exchangeable Na+,ESP,SAR and pH)of alkaline soil when they were used as amendment to ameliorate sodic soil.Two kinds of alkaline soils,strongly alkalized soil and alkaline soil,were tested in this experiment,with four levels of desul-phurisation products,3 g kg^-1 and 3.6 g kg^-1 for the former and 7 g kg^-1 and 8.4 g kg^-1 for the latter.The results show that exchangeable Na+,ESP,SAR and pH decreased significantly after desulphurisation products were applied and the soils were leached in all the treatments,and the soils were improved.The effects of high rates of desulphurisation products were much better than of the low rates.After 3.6 g kg^-1 and 8.4 g kg^-1 of desulphurisation products were applied,respectively,in the 0~40 cm surface layer of the strongly alkalized soil and 0~20 cm surface layer of the alkaline soil the chemical indices were all reduced to ESP<15,SAR<13 and pH<8.5,the criteria for moderately alkalized soils.

Abstract:Eco-toxicological effects of germanium on activities of catalase,dehydrogenase,urease,phosphatase and invertase in brown-yellow soil were studied by means of indoor culture and pot culture experiments.The results showed that when Ge concentration ranged between 2~200 mg kg^-1 in the soil,its inhibiting effect on soil dehydrogenase,phosphatase and invertase was not significant,but quite so the activity of soil catalase and urease;especially the latter.A significant negative relationship between urease activity and Ge concentration of soil could be observed,so it is feasible to use inhibition rate of soil urease as a bio-indicator for ecological risk assessment of Ge pollution in the soil.

Abstract:A triazophos degrading bacterium designated as mp-4 was isolated from soils that have long been subjected to organophosphate pollution.Strain mp-4 was identified as Ochrobactrum sp.based on its biochemical-physiological characters and the result of the 16 S rDNA homologue sequence analysis.Strain mp-4 can grow with triazophos as its sole carbon source and degrade it at a rate of 98.3% .The optimal growth temperature and pH for mp-4 are 30℃ and 6.6 respectively.At the temperature of 27~32℃ and pH of 7.5~8.8,mp-4 can degrade triazophos well.Field test results show that mp-4 can decrease the residue of triazophos in rice husk and brown rice by 91.9% and 100% ,respectively.

Abstract:Investigations were conducted on dynamics of grain yields and nutrients uptake of rice,and ecological characteristics of soil microorganisms in a paddy field under long-term fertilization experiment,which was designed to have five fertilization treatments,CK(control),PK,NK,NP,and NPK,and two crop treatments,conventional rice and hybrid rice.The results show that grain yield of rice was positively correlated with the total uptakes of N,P and K,and the soil available nutrient pool depleted rapidly under consecutive cropping without fertilization.The results also show that balanced N,P and K application improved functional diversity of soil microbes and increased total microbial biomass of the soil.Unbalanced fertilization decreased microbial N but increased C/N ratio of the soil microbial biomass.It is found that soil nutrient deficiency and unbalanced fertilization to rice crops have a negative effect on diversity of microbial communit ies and total microbial biomass in the soil.

Abstract:Qizhuan 39 was a genetically modified strain of rice stemming from an indica rice cultivar,Qisiruanzhan,by accepting 2 anti-fungus genes,"RC24"(a rice chinase gene)and "β-1,3-Glu"(a alfalfaβ-1,3-Glucanase gene).Preliminary analysis showed that there were fewer endophytic bacteria and endophytic fungi in the roots of Qizhuan 39.The numbers of bacteria and fungi in the rhizosphere of Qizhuan 39 were markedly lower than of Qisiruanzhan,but near to those of Zhuxian B(another non transgenic control).In the earing period,there was no remarkable difference in the rhizospheric soil between Qizhuan 39 and the controls in concentration of soluble organic matter,nitrogen,phosphorus,and the activities of polyphenol oxidase,hydrogen peroxidase,sucrase and urease.The amount of humic acid in the soil during the rotting process of transgenic rice residue was the same as in the non-transgenic control.There was no remarkable detrimental effect on growth of rice in next season after growing Qizhuan 39.

Abstract:Bentonite and lignin were blended and prepared into a kind of releasing-controlling material,which was then used as coating for manufacture of coated-controlled-release fertilizer.The scanning electron photomicrographs showed that the coating was thinner,with fewer cracks and more compact intergranular deposit than the coating of mere bentonite.The soil column leaching test indicated that the cumulative N leaching rate of the urea coated with either bentonite or the complex within 50 days was much lower than that of common urea.In three coat ing treatments,it decreased by 8.61% ,14.01% and 15.22% , respectively,in comparison with CK,common urea.The total N leaching of the two treatments using complex materials as coating was 11.31% ,13.83% lower than the treatment using bentonite as coating.The pot and field trials also showed that application of urea coated with either complex could significantly increase crop yield and N recovery rate,suggesting that it is advisable to use.The mixture of bentonite and lignin as coating material,which suits the conditions of the country in developing controlled-release fertilizer.

Abstract:Soil thermal properties include thermal capacity,thermal diffusivity and thermal conduct ivity.They are in trinsic factors for determining soil thermal conditions and closely associated with soil water conditions.Thermo-Time Domain Re flectometry has many advantages,such as low cost,less disturbance of the soil and time-saving,thus showing great potential in soil research.In this paper,we introduced calculation models for and status of the research on soil thermal properties,with em phasis on development of the theory and technology of a new method.Thermo-Time Domain Reflectometry,for determination of soil thermal propert ies,and advances in its application to the research on soil water and other soil physical properties.The new method has recently been extensively used abroad but quite limitedly at home.It is worth further popularizing in related research fields in the country.

Abstract:The ways in which earthworms perform as bioindicators of soil pollution are reviewed as follows:(1)Earth-worm population in contaminated sites reflects the degree of soil pollution as a whole;(2)For ecotoxicologial risk assessment, earthworms serve as an important indicator for potential pollutants damaging the soil eco-system;(3)Earthworms act as an early warning system in monitoring changes in soil pollution.The main mechanisms of earthworms.resistance to metal pollutants are also elaborated:(1)its lipid ant ioxidative enzyme system helps relieve the stress of oxidation;(2)Compartment and immobilization of metals;(3)Process of chelating and detoxicification;(4)Lysosome and cellular plasmid are activated to restrain activity of heavy metals.Meanwhile,the potential of earthworms to enhance soil bioremediation is discussed and it is believed that earth-worms do so by improving physical and chemical characteristics,activating microbes,changing bioavailability of pollutants in soil.

Abstract:随着我国的快速城市化,城市边缘区土地利用类型多元化,土壤面临巨大的环境压力^[1]。研究城市边缘区土壤环境污染、搞清污染物在城市边缘区土壤中的分布特征,对于预防和治理土壤及环境污染、城市规划乃至城市化发展道路,无疑具有重要意义。近20多年来,北京经历了一个高速城市化时期^[2],北京城郊的土壤污染研究也逐渐增多^[3~5]。所以北京城市边缘区土壤重金属污染物分布特征的研究,对北京及全国的防治环境污染和城市化发展都具有理论及现实意义。

Abstract:产地土壤环境质量是影响无公害干果安全质量的最基础因素之一^[1~3]。无公害生产要求土壤重(类)金属必须控制在一定限量范围内,以协调土壤生态平衡,维护人体健康,保障生产的可持续发展。然而,由于土壤系统的复杂性,重(类)金属元素在化学、生物学效应以及与环境互作等方面都存在着比较大的变异性,所以,与大气、灌溉水污染物限量指标相比较,土壤污染物限量标准的制订是最为复杂的,也是最容易引起争议的。因此,迄今为止,世界上大部分国家尚无统一的土壤环境质量标准^[4]。

Abstract:在我国南方热带、亚热带地区分布有大面积的酸性红黄壤^[1],这类土壤的一个重要特征是它们的表面既带正电荷又带负电荷,而且电荷数量随环境条件而变化^[2]。可变电荷土壤既可吸附阳离子又可吸附阴离子,而且对某些离子具有一定程度的专性吸附^[2]。研究结果表明,NO₃^-是一个以电性吸附为主的阴离子^[2],共存于体系中的阴离子如Cl^-和SO₄^2-都会抑制土壤对NO₃^-的吸附^[3],从而降低土壤对氮的保肥能力,同时增加了NO₃^-在土壤中的移动性。Qafoku和Sumner的研究结果表明,可变电荷土壤对NO₃^-的吸附主要受土壤的矿物组成、表面电荷、pH和溶液离子强度的影响^[4]。

Abstract:作为“地球之肾”的湿地,具有均化洪水、调节气候、污染物降解、防止自然力侵蚀等众多的功能和用途。湿地效益研究就是将湿地的这些功能、用途及属性给以定量化、货币化。目前对湿地均化洪水效益研究中大都考虑湿地对地表水的均化作用^[1],(1),缺乏对湿地土壤均化洪水的定量、系统研究。而湿地土壤的孔隙度大,储水能力高,可以保持大于其本身重量3~9倍或更高的蓄水量,因此湿地土壤的均化洪水效益是不可忽视的。本文利用野外测得数据和GIS手段,结合地统计分析方法,定量研究湿地土壤的均化洪水效益,可以弥补在这项研究中的空白。

Abstract:细沟侵蚀在坡面水蚀中占有重要地位,用模型模拟预报细沟侵蚀具有重要意义。以往对细沟发育的研究主要停留在定性描述上,缺少对过程的定量分析。现有的基于物理过程基础上的侵蚀预报模型,如水蚀预报模型 WEPP(Water Erosion Prediction Project),从概念上可以模拟侵蚀产沙的时空变化,但模型中的参数如细沟净剥蚀率、输沙能力、土壤可蚀性参数等取值困难、过程繁琐,限制了过程模型的验证以及在细沟侵蚀预报中的实际应用^[1,2]。

Abstract:干旱缺水与水土流失并存是制约干旱半干旱地区经济社会可持续发展的主要限制因子,坡面降雨径流既是产生水土流失的动力,又是缓解干旱缺水的重要水源。通过地表径流调控手段,消除水土流失动力,同步实现水土流失治理与水土资源高效利用一直是近年来人们研究的热点课题。近年来,采用化学措施防治水土流失已成为新的研究领域。高分子聚合物以其独特的结构和多样的功能以及低廉的价格用于改良土壤结构,调节降雨径流,已是我国农业及水土保持研究的热点。

Abstract:土壤的光谱反射率是土壤内在的理化特征之光谱行为的综合反应^[1]。Stoner^[2]比较详细地描述了五大类土壤光谱反射曲线类型及其与土壤性质、土壤发生分类的关系。戴昌达等^[3]根据 360~2 500nm的土壤光谱反射率,将我国主要土壤的光谱反射特性曲线划分为平直型、缓斜型、陡坎型和波浪型四类。王深法等^[4]对浙江省石灰土光谱特征进行分类研究,对起源不同、发育程度不同的石灰土,利用石灰土的心土层的光谱特征量为参数,进行判别归类,取得了满意的结果。吴豪翔等^[5]对南方山地丘陵的砖红壤、红壤、黄壤、水稻土和紫色土的光谱特征进行了分析,为土壤的发生分类研究提供了光谱的定量指标。