Abstract:Atrazine is an herbicide commonly used on summer maize throughout North China,where the growing period of summer maize coincides with the rainy season.It is,therefore,of great significance to protection of the shallow groundwater environment to assess leaching risk of atrazine at filed scale.In this study,with a small agricultural plot (27 m 27 m) at Yongledian Experimental Station,Tongzhou District,Beijing as background,soil samples were collected and analyzed for soil physicochmical propert ies and the meteorological data of the year of 2001 were gathered.On such a basis and the assumption of column model,numerical simulations of the spatial distribution of atrazine leached dynamics at field scale were conducted with spatial variability of the soil hydraulic parameters and the atrazine transport and adsorption parameters taken into account.And then geostatistical analysis was carried out of spatial variance structure of soil water negative pressure,water flux and atrazine concentration at 20 cm depth during the growing stage of summer maize.Results show that,variograms of the three variables during the summer maize growing season were basically spherical models,and most variograms had ranges about 8 to 10 m.This approach of the study can be used as reference in designing and laying out a monitoring network for water movement and atrazine transport at field scale.

Abstract:The methods of (NH₄) ₂SO₄-H₂SO₄- diantipyryl methane colorimetry and NaOH melting-diantipyryl methane colorimetry were used separately to extract and determine the amorphous titanium and total titanium in some purple parent rocks and soils in the Sichuan Basin.The total/amorphous titanium was defined as/titanium value 0,which was used for estimating weathering degree of purple parent rocks instead of SiO₂/(Al₂O₃+Fe₂O₃) value.The results show that of the contents of total titanium in six purple parent rocks in the Sichuan Basin varied in the range of 2195~2010 g kg^-1,which is a middle level on the high side,and the six parent rocks in terms of lithology were in a decreasing order of shale > mudstone > siltstone > sandstonem.The total titanium was obviously in negative correlation (r=-0.7459) with SiO₂ in these rocks.itanium value was reversibly correlated to weathering degree.According to the titanium value of the rocks,weathering degree of the six purple parent rocks were lined in an rising order of Trias T₁f< Jurassic J₂s< Jurassic J_1-2^z< Jurassic J₃p< Jurassic J₂sn< Cretaceous K₂j.The order of weathering degree of the purple soils based on titanium values basically tallied with that based on SiO₂/(Al₂O₃+Fe₂O₃) values,with correlation coefficient reaching an obvious level (r=0.8615^**).The correlation coefficient between the titanium value of soil colloid and the SiO₂/(Al₂O₃+Fe₂O₃) value also reached an obvious level (r=0.8757^**).The weathering degree showed by the titanium value of the soil is in accord with that showed by purple parent rocks.

Abstract:According to the official history,during the period from 300 to 1909 A.D.,China witnessed a total of 436 dust storms,which lasted a total of 901 days.The product td (t,the number of dust storms in every ten years,d,the days the dust storms lasted),may be used as an index of frequency of dust storms in different periods,and may also be regarded as an index of aridification degree of soil environment.Dust storm frequent periods,≥ 30 years,were distributed in 480～509,1170～1219,1690～1729 and 1840～1879 A.D.These periods with td values ≥ 25 corresponded to the cold periods in the history.Cold and dry periods are prone to triggering dust storms.During the 1610 years studied,the average dust fall for every year is about 0.54 cm.Aeolian process of the loess is still going on nowadays.

Abstract:To quantify spatial variability of soil water is of important significance for ecological environment restoration in Karst regions.The geostatistics method is used to determine and quantify spatial variability of surface soil water(0～5 cm and 5～10 cm) for analysis of spatial patterns of soil water in a typical karst depression(150 m×50 m) in Guzhou.Using the grid sampling method(5 m×5 m space),341 sampling points are fixed in total.Based on autocorrelation analysis,spatial correlation structure of these soil moisture patterns is calculated with the aid of the Moran's I index.Results indicate that the soil water contents in the two layers have a simple pattern of periodic variations,and patches with the same spatial autocorrelation character correspond to soil continuum and rock distribution in area.Sample variograms are found to have an anisotropy character in the whole research area.And in different patches,the semivariograms show different structure characters.The soil continuum patch has a low sill and a long range,whereas the rock distributed patch has a high sill and a short range.Such soil water patterns can be explained by the effect of bare rock distribution and the topography of the research area.Based on the soil water content data,spatial scaling of soil moisture is further studied.The range of the soil water is increased with the sample spacing.This implies that when the spatial pattern is controlled by plural factors of different scales,sample spacing should be decided by the aim and precision of the research.The findings of this study may help improve the sampling design in the research on soil moisture in the Karst regions.

Abstract:Pollution characteristics,bioaccumulation and potent ial health risk of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were preliminarily studied in typical farmland soil-ecosystems of Yangtze River Delta region.The results showed that averaged concentration and TEQ of total PCDD/Fs in the farmland soil were 556 pg g^-1dw and TEQ 2012 pg g^-1 dw.The bioaccumulation of PCDD/Fs was clearly observed in different biological tissues.The concentration and TEQ of PCDD/Fs were 5017 pg g^-1 dw and TEQ 614 pg g^-1 dw in the rice,3512 pg g^-1 dw and TEQ 617 pg g^-1 dw in the stems and leaves of vegetables,3019 pg g^-1 ww and TEQ 517 pg g^-1 ww in the chicken meat.The tolerable daily intake(TDI) values estimated based on the following exposure ways of rice-vegetable,rice-vegetable-Houttuynla cordata Thunb,rice-vegetable-Hout-tuynla cordata Thunb-chicken meat were TEQ 6714,7211,8315 pg kg^-1d^-1,respectively,which all were higher than the tolerable daily intake(TDI) (TEQ 1~4 pg kg^-1 d^-1) for PCDD/Fs recommended by the World Health Organization(WHO).It is concluded that bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) from the farmland ecosystems has posed potential risks to agro-product safety and human health in the typical contaminated area.

Abstract:Salt in greenhouse soils was studied in Shouguang,Shandong Province.The results indicate that 1) the salt content in greenhouse soils was much higher than that in open field soils,with an average value being 2.69 g kg^-1(CV=58%) and only 0.61 g kg^-1(CV=14%),respectively,in 0～20 cm soil layer;2) the salt content in greenhouse soils might reach the threshold value for normal growth of crops after 4 years of cultivation,and secondary salinization of the soil is a main limiting factor for sustainable development of greenhouse cropping;3) apart from HCO₃^-,the contents of NO₃^-,SO₄^2-,Cl^-,Ca²⁺,Mg²⁺,K⁺,Na⁺ increased significantly in greenhouse soils,and Ca²⁺and NO₃^- were the majorions in the soils,accounting for 47.4% and 19.3% of the total salt in the topsoil,respectively;and 4) compared with neighboring open field soils,greenhouse soils displayed apparent phenomena of salts leaching downwards to the bottom of the soil(80～100 cm) and salts accumulating in the topsoil(0～20 cm),especially NO₃^- that has seriously affected quality of the groundwater in the area.

Abstract:Assessment of soil fertility quality was an effective way to evaluate direct or indirect impacts of artificial land managements on the soils.This paper attempted to present an integrated evaluation of Hong Kong soil fertility quality with improved analytic hierarchy process (AHP) since such study had never been carried out on the soils in Hong Kong before.Soil samples were collected from 51 representative soil profiles indicative of varied soil types throughout Hong Kong,and 10 items of soil properties,including pH,soil organic matter,soil texture etc.,were determined.Results indicate that more than half of the soil samples were below the middle level in soil fertility,while those from farmlands was relatively better and higher than 0.7 in soil fertility quality index(FI),which was applied to quantify soil fertility in Hong Kong.The low soil fertility quality is attributed mainly to the strong acidity and low contents of total phosphorus and rapid available phosphorus of the soils.Besides,mountain fire and soil erosion contribute to a certain extent to degradation of the soil quality.Therefore,it is suggested more efforts be devoted to protection of vegetation and conservation of soil and water for the sake of improvement of soil quality.

Abstract:Bioavailability of heavy metals in soil depends on composition of the soil.Characterization of heavy metal distribution among different size fractions of the soil is needed for better understanding of the fate of heavy metals.This study investigated distribution of organic carbon,nutrients,and heavy metals among different size fractions in sandy soil.Results show that heavy metals,including Cd,Co,Cr,Cu,Ni,Pb,Zn and Mn,in the sandy soil were significantly enriched in particulate organic matter(POM),with Cu and Zn in particular,which were much higher in concentration than the others.It was more significant in 0 05~1 mm POM fraction than in >1 mm POM fractions.The enrichment in the POM fractions varied with soils,and was positively related to accumulation of the metals in the soils.The enrichment of heavy metals in the POM fractions was not completely due to decomposition of plant debris.The strong heavy metal adsorption capacity of POM in the soil might be an important machenism of heavy metal enrichment in POM fractions.

Abstract:Based on long term stationary experiment,effects of long-term nitrogen application on yield,carbon-nitrogen assimilation of leaves and soil nitrogen in permeable paddy soil in the Tai Lake region were studied Results show that no significant difference was found between the treatment applied with N 161.0 kg hm^-2and treatments applied with more nitrogen than N 161.0 kg hm^-2 in either yield or in carbon-nitrogen assimilation rate in leaves at the jointing,booting and filling stages.But all these treatments were higher than the treatments applied with N 57.5 kg hm^-2 in both indices.Analysis of nitrogen distribution in soil profiles reveals that soil N residue went down the deepest in the treatment applied with organic manure plus NPK,which was followed by treatments applied with N 161.0 kg hm^-2 or more in chemical fertilizer.And N residue was found the shallowest in the treatment of incorporation of crop stalks into the soil plus N application.

Abstract:A 3-year field experiment was carried out to determine effective methods of applying phosphate rock (PR) at a rate of P 120 kg hm^-2a^-1 on an acid paddy soil derived from quaternary red clay in a rapeseed-ric-erice cropping system.The yield response of rapeseed to application of phosphorus fertilizer(PF) was much greater than that of rice.SSP was applied separately to rapeseed,early rice,and late rice,while PR was applied only to rapeseed.Kunyang phosphate rock(KPR) was found to be significantly less effective than Gafsa phosphate rock(GPR) on rapeseed,but quite similar on rice.Relative agronomic effectiveness of GPR and KPR in rapeseed,early rice,and later rice seasons were 108.7%,105.0%,99.6%and 89.4%,104.8%,97.1%,respectively.Increasing the application rate of GPR from P 120 kg hm^-2a^-1 to P 240 kg hm^-2a^-1 or mixing RP with SSP and applying the mixture to separately to three crops did not have any extra effect on yields of rapeseed or rice.Available P in the cultivated layer of soil after the rapeseed season was greater than that after the rice seasons.Phosphorus absorbed by rapeseed was mainly from the PF,whereas P absorbed by rice was mainly from soil.

Abstract:Change in forms of phosphorus in a typical Hapli-Udic Isohumosols(black soil) under a 15-year long-term fertilization experiment was studied.Results show that accumulation of soil Al-P and Ca₂-P was positively related to P application rate;application of NK stimulated the plant to absorb Ca₈-P;and the concentration of Occluded-P(Oc-P) was decreased.P application did increase the content of Fe-P in the black soil,but did not the content of Ca₁₀-P.In terms of content in the black soil,the various forms of in-organic P were in the order of Fe-P>Ca₁₀-P>Al-P>Ca₈-P>Ca₂-P>O-P.P fertilizer application increased organic P in the soil,but it did not increase the content of organic matter.Instead,the content of organic matter dropped to a varying degree in different treatments.Application of N 112.5 kg hm^-2 a^-1and P 20 kg hm^-2 a^-1 could keep I-P in balance in the soil.

Abstract:A two-year field experiment with plots of early rice applied with different rates of phosphorus fertilizer(P₂O₅ 0, 30,60,90,120,150 kg hm^-2) were carried out in 2003 and 2004 to study residual effect of P on the yield composition of late rice.According to the correlation analysis of effective ears number,grain number per ear,maturity degree,1000-grain weight,and grain yield with P application rates,it could be concluded that P residual effect was significant mainly on effective ears number and grain number per ear and eventually the yield of rice.The more phosphorus fertilizer applied on early-rice,the higher the yield increase rate of late-rice.Owing to the difference of rainfall between 2003 and 2004,the P residual effect on late-rice yield was different.P could play an important role in improving the ability of late-rice to stand drought.It is therefore recommended that the application rate of P should be in the range from 85 to 135 kg hm^-2.

Abstract:Components of chemical groups in soil humic acids (HA) and fulvic soids (FA) isolated from soils different in fertilization treatment were studied with the aid of infrared spectrum (IR) and 1H nuclear resonance spectroscopy (NMR),and effects of different fertilization treatments on chemical group structure of the humus were explored.The results show that fertilization affected structure and content of soil humus,and aromatization degree and fraction of simple organic molecules in HA isolated from fertilized soils.The effect was greater in Treatment NPK than in Treatment PK.The 1H NMR results show that the relative content of carbonhydrate H of FA is the highest in the treatment of long balanced fertilization(NPK treatment),while the relative content of aliphatic H is higher in Treatment PK.

Abstract:A pot experiment was conducted with different DDT concentration,i.e.0,0.5,5.0 mg kg^-1 respectively,to study residue dynamics of DDT and its main metabolites in paddy soils with and without ryegrass growing.The total growth period was 81 days.The results indicated that the residue of DDTs decreased steadily with the time and at a greater rate in the earlier stage.Compared to the soils without ryegrass growing,DDTs in the soils under ryegrass growing decreased by 27.26% and 20.50% respectively by the end of the experiment,for the 0.5 and 5.0 mg kg^-1 treatments,and significant differences in p,p DDT residue were observed on the 16th,32th,64th and 81th day.It could be contributed to the release of enzyme and other organic secretions from plant root systems,which could effectively stimulate degradation of DDT.Additionally,DDE in creased gradually along with the time.

Abstract:There are several ways available to measure diversity of biological communities,but the methods of diversity index and species-abundance pattern are the common ones used.To get to know characters of a community,the species-abundance pattern method is more efficient than the diversity index method.In this paper species-abundance distribution of soil animal communities in different positions of a sloping field was studied with a view of introducing a species-abundance distribution model into the study on soil fauna and disclosing in depth the spatial pattern of soil fauna diversity in a micro-region.Based on investigation of the macrofauna and mesofauna communities in piedmont,and the lower,middle and upper parts of a sloping field in the Zuojia Nature Reserve,Jilin Province,China,and by using the log-series distribution model,log-normal distribution model and broken-stick model for fitting of the curves of the species-abundance of the macrofauna and mesofauna communities in different parts of the sloping field,with species-abundance as index,spatial distribution patterns of species-abundance of the two types of soil fauna communities were studied.Results of the analysis were collated with traditional Shannon-wiener index,Pielou index and Mackintosh index.Mechanisms of the formation of such patterns were analyzed and explained,taking into account the character-istics of the natural environment of the study zone.The results showed that the log-series and log-normal distribution models fit well the species-abundance distribution of soil fauna communities,displaying a pattern of enriched species being few,and rare species being plentiful,but the broken-stick model could not.All in all,species was positively correlated with abundance and log-series was the best model.Compared with the traditional method of diversity indexes,the species-abundance pattern was more intuitionistic and more vivid in expressing the characters and difference in diversity of soil fauna communities between different parts of the sloping field.

Abstract:Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments,making them important in the global cycling of nitrogen.In order to analyze the mmonia-oxidizing bacteria population structure in red soil enrichment culture,a pair of AOB-specific primers was designed,and total microbial genomic DNA of enrichment culture was extracted by the direct method of PCR-amplification template.An AOB-specific 16S rDNA clone library was subsequently constructed.RFLP analysis of 16S rDNA was conducted using enzymes(HhaⅠand RsaⅠ) to digest 16S rDNA from the library.The randomly selected 35 cloned fragments were finally clustered into 3 different phylotypes,with the most abundant phylotype accounting for 94% of the selected 16S rDNA clones and the other two phylotypes for 3%,respectively.Seven clones from 3 phenotypes were sequenced and the 16S rDNA sequences were compared with those from GenBank.Based on the Blast analysis,a lot of Nitrosomonas-like sequences were found in this library.The result shows that there are ammonia-oxidizing bacteria in the red soil and Nitrosomonas sp.is a dominant bacterium in enrichment condition.

Abstract:en known strains of bacteria were used to study validity of the Sherlock Microbial Identification System(Sherlock MIS) in identification of soil bacteria.Results show that Sherlock MIS is accurate in identifying all the bacteria,incubated in TSBA(Trypticase soy broth agar),except Bacillus thuringiensis,whereas it is not so ideal,when the bacteria are incubated in BPA(beef peptone agar).A better result can be obtained when the conserved bacteria are activated twice or for 48 hours than for 24 hours.No difference is found in identification between bacteria sampled from quadrant 3 and quadrant 2.

Abstract:A bacterial strain Bacillus latersprorus DSP capable of degrading chlorpyrifos was isolated from soil.Degradation characteristics of chlorpyrifos by the strain DSP were investigated in pure culture system under conditions of pH 7.0,25℃ and biomass of OD₄₁₅ 0.2.The half-life of chlorpyrifos at concentrations of 1 and 10 mg L-1 was measured to be 1.48 d and 5.00 d, respectively.The chemical showed obvious inhibitive effect on degradation capability of the strain,when its concentration reached as high as 100 mg L^-1.The degradation rate of chlorpyrifos by the Strain DSP was affected by pH and temperature showing an order of pH 7.0>pH 5.0>pH 9.0,and of 35℃>25℃>15℃,respectively.A plasmid with a size of approximately 20 kb was found in Strain DSP.The strain lost its ability to degrade chlorpyrifos when the plasmid was removed by acridine orange and heating.When the plasmid was transferred into Escherichia coli JM109 and back into plasmid-removed DSP the transformants obtained the ability to degrade chlorpyrifos.These observations indicated that the plasmid of Strain DSP is responsible for the degradation of chlorpyrifos.

Abstract:Two controlled experiments were conducted to evaluate the potential for desert species to emerge and establish and to assess whether easily measured plant traits can be used to predict their probable success.In the experiments 5 species of shrubs and semishrubs common in the desert in Northwest China were used.First,a glasshouse experiment was performed to test the effect of sand burial on seedling emergence.Second,a growth experiment was conducted to measure relative growth rate and other growth parameters of seedlings between 7 and 28 days of age.In the burial experiment,the phenomenon of high seedling emergence concentrated at 0~3 cm for the most species examined.The number of days from sowing seeds to seedling emergence was significantly affected by sand burial depth.Seed mass was strongly correlated with the slope of emergence versus burial depth.In the seedling growth experiments,seed mass is positively correlated with AGR and RGR,which may help to explain their prevalence in the desert.RGR was positively correlated with ULR and SLA,however,it was negatively correlated with LAR and LWR.Seed mass was not correlated with ARPR,however it was negatively correlated with RLR and R_L/LA,indicating that smal-l seeded species tended to produce much longer and thinner roots in relation to total seedling mass than larger-seeded species.Seed mass and ULR should help predict their emergence and growth in the desert,however,seed mass and relative growth rate alone do not necessarily predict establishment success.

Abstract:The early of 21st century is a key period for China to build up a holistic well2off society and accelerates socialist modernization.As a result,its land demand in economic construction is growing dramatically,bringing about greater pressure and challenges to protection of cultivated.In the situation that the cultivated land is decreasing drastically with each passing day, the protection of cultivated land has becomes a major factor affecting sustainable development of the society of the country.Based on analysis of the changes in cultivated land resources of the country in the period of 1949～2004,and negative impacts of the decrease in cultivated land in recent years,trend of cultivated land in 2020 is predicted by scenario,and strategies for handling properly the relations between the protection of cultivated land and the economy development and between sustainable utilization and protection of the cultivated land.

Abstract:COMET assay is a newly developed technology for detecting DNA damage on single cell level.Recently and after continues modification,the assay has been successfully modified to detect several DNA damages and become a sensitive biomarker.It also plays a more and more important role in identifying genotoxic substances from environmental sample,elucidating mechanisms of carcinogenicity,as well as biomonitoring environmental pollution.COMET technology has also been applied in environmental toxicology and risk assessment.In this paper,the origination and modification,environmental applications,and future trends are reviewed,for the benefits of utilization,data interpretation,and contributing to its further development by Chinese scientists.

Abstract:土壤种子库是指存在于表层土壤(包括凋落物)中具有生命的种子,是植被天然更新的物质基础^[1~3].土壤种子库时期是植物种群生活史的一个重要阶段,有人称为潜种群阶段,它能部分的反映群落的历史和现状,对退化草地生态系统的恢复起着重要的作用^[4~6].土壤种子库中的长命种子不仅具有重要的遗传学意义,而且还被认为是植物种群基因多样性的潜在提供者^[7].所以,土壤种子库在维持种群和群落的物种多样性和遗传多样性方面具有重要的意义^[4].在植物种群生态学研究中,土壤种子库问题一直受到广泛关注,国外近20a来,对土壤种子库的研究一直是植物种群生态学中比较活跃的领域^[5].

Abstract:土地荒漠化是当今世界环境、社会和经济所面临的一个最大问题.它是以风沙活动为主要标志,包括土壤风蚀、风沙流、风沙沉积和沙丘前移的一系列过程,其中土壤风蚀是导致土地沙漠化的主要原因和首要环节.我国是世界上受沙漠化影响最严重的国家之一.全国沙漠、戈壁和沙漠化土地约为165·3万km²,分布在干旱、半干旱地区以及部分半湿润地区^[1].影响风蚀的因素是多方面的,当土壤中有水分存在时,水分子与土壤颗粒之间的拉张力增加了颗粒间的内聚力^[2],因此增加了土壤的抗风蚀性.Chipil^[2]和Bisa等^[3]分别利用风洞研究了土壤含水量与风蚀之间的关系,认为土壤含水量是抑制风蚀的主要因素之一.

Abstract:20世纪90年代中后期以来,随着“3S”技术和地统计学方法越来越多地应用于我国土壤学领域^[1],以及“精准农业”(Precision agriculture)在我国的引进和部分地区的初步应用^[2~4],对土壤特性尤其是土壤养分空间变异性的研究日益引起学者的关注^[1~3,5~7],其中以北方土壤及管理种植模式为研究对象的较多^[1~6],南方相关方面的研究报道较少^[7,8].从理论上讲,在田块面积相对较小、田块间土壤养分变化较大的中国南方地区,比发达国家土壤养分相对一致的大农场和我国北方地区更需要应用养分精准管理技术.

Abstract:河北省某地区是我国特种作物-金丝小枣的主要产区,由于农药的大量使用,导致农药残留污染影响农产品品质,而且会造成地水的严重污染,直接危害身体健康.微生物由于种类丰富,代谢途径多样,其转化、降解各种化合物潜力巨大^[1,2].从20世纪60年代开始,国内外就开展严重污染环境的异生物质的微生物降解研究,筛选分离了大量降解性微生物^[3~5],并且开发了各种微生物降解制剂及配套产品应用于原位生物修复^[6~8].六六六(HCH)是有机氯类高毒、持久性污染物,虽然在我国已禁用20多年,但在该地区的土壤中仍然存在;呋喃丹是氨基甲酸酯类农药,由于其毒性大、残留高,近年虽已控制使用但残留情况仍然严重.

Abstract:土壤粘土矿物中层状硅酸盐与氧化物共存及晶质和非晶质共存.土壤中含钾的粘土矿物主要有水云母、蛭石和绿泥石等.这些粘土矿物影响土壤钾素的固定和释放,进而影响土壤钾的生物有效性.有研究表明,土壤中的层状硅酸盐矿物彼此之间存在着一种相互演变的关系.例如在云母风化初期,通常会出现水化云母,在钾比较丰富的条件下,就会出现伊利石;水化云母进一步风化并释放出更多的钾以后,则形成蛭石和蒙脱石.相反,蛭石和蒙脱石在吸收了钾离子并脱水后,也可以向伊利石及云母类矿物转变.以往研究往往从发生学观点探讨不同土壤类型的粘土矿物组成,很少涉及人为施肥的影响.

Abstract:水稻是一种喜水作物,具有半水生或湿生的习性,淹水栽培不仅耗水量巨大,而且严重浪费水资源.我国是世界水资源严重缺乏的国家之一,水资源已成为我国农业生产的重要限制因素.近年来在一些缺水、少雨地区旱作水稻发展很快,节水效果显著.当前有关旱作水稻栽培研究报道颇多,但主要是着力于品种选择及生理特性研究^[1~6].氮肥是影响水稻生长的重要因素之一.氮肥运筹对水稻生长及产量影响前人已做了大量研究报道^[7,8].关于旱作水稻的氮素吸收动态特征,石英等已做了研究报道^[9,10].