Abstract:Paleosols and sediments are important archives for studying ancient human activities. A soil profile labeled as YC1 was located at Yuchisi, Mengcheng County, Anhui Province, where relics of the Dawenkou Culture and Longshan Culture were detected. Elemental concentrations, such as Pb, Al, as well as the lead isotopes, were analyzed in soil samples collected from Profile YC1. Pb enrichment in the soil layer from 5 050 cal a BP to 4 000 cal a BP, was characterized. Results show that Pb enrichment factors varied from 1.0～1.8 in the cultural layers, and were not quite high. However, with the history going on from the Dawenkou Culture to the Longshan Culture, the Pb enrichment factor displayed an obvious rising trend, which indicated that the Pb in the cultural layers was probably associated with the development of metallurgic activities in the middle stage of the primitive society. From 5 050 cal a BP to 4 000 cal a BP, China underwent Stone Age, Chalcolithic Age and Bronze Age in sequence. Pb dust in the atmosphere increased with intensifying utilization of copper resources, which was probably the main cause of the rising enrichment factor in the cultural layers. The measurements of lead isotope in the cultural layers show the ratio of ²⁰⁶Pb/²⁰⁴Pb varied from 18.3～19.8, with an average being 18.82; the ratio of ²⁰⁷Pb/²⁰⁴Pb from 15.3～16.5, with an average being 15.76; the ratio of ²⁰⁸Pb/²⁰⁴Pb from 38.0～41.0, with an average being 39.04. The tracing study shows the sources of lead in the various cultural layers multiplied from 5 050 cal a BP to 4 000 cal a BP, which was most likely related to ores from South China, including Yunnan, Sichuan, Hubei, Hunan or Guangdong Provinces.

Abstract:To study multiple origins of magnetic minerals in soils, comparison was made between paeosols in the Loess Plateau, China and urban soils in Shanghai in magnetic properties. Results show the mean values of magnetic susceptibility (χ_lf) and frequency-dependent magnetic susceptibility (χ _fd %) of the paleosols in the Loess Plateau are 108×10^-8 m³ kg^-1 and 11.4%, respectively; and the two are positively and significantly correlated (p≤0.01), suggesting that the magnetism enhancement in the soils is mainly attributed to the formation of pedogenic superparamagnetism (SP) grains. Significant positive correlations of χ_lf with free iron (Fe_d), free iron degree (Fe_d/Fe_t) and clay content also suggest that the magnetism enhancement in the soils is closely related to pedogenesis. Magnetism of the urban soils in Shanghai is unusually enhanced, with χ_lf ranging from 127 to 1 959×10^-8 m³ kg^-1, and χ _fd % being mostly <2.0%, indicating little SP grains formed, which suggests that the magnetic enhancement of the urban soils is not caused by pedogenesis but by anthropogenic activities. The study of magnetic parameters of their combinations, such as anhysteretic remanent magnetization（χ_arm）, anhysteretic remanent magnetization/saturated isothermal remanent magnetization (χ_arm/SIRM),χ_arm/χ_lf and SIRM/χ_lf, reveals that the urban soils are dominated by multidomain (MD) and stable-single-domain (SSD) grains; while the paleosols in the Loess Plateau by superparamagnetism (SP) grains. The magnetic parameters of soft isothermal remanent magnetization (SOFT), hard isothermal remanent magnetization (HIRM), SOFT percentage (SOFT%), HIRM percentage (HARD%) and IRM_{300 mT}/SIRM (F_{300 mT}) indicate that the urban soils are dominated by ferrimagnetic minerals, with low coercivity and high magnetic soft fraction and the paloesols in the Loess Plateau are also dominated by ferrimagnetic minerals, which are, however, higher in HARD%. The magnetic parameters and their combinations are effective means to discriminate between pedogenic and anthropogenic magnetism in soils.

Abstract:Based on analysis of the pluviometric data of 408 rainfall events in 8 years at Lanxi and Shengzhou Soil and Water Conservation Experiment Stations in Zhejiang Province, 3 factors, i.e. monthly erosive rainfall (P_mer), number of days of erosive rainfall in a month (D_mer), and maximum 3-day rainfall in a month (Z_3m ), were proposed, and a computation method defined, And both were introduced into the monthly rainfall erosivity models. The method of excluding low intensity rainfall, using of P_mer/ D_mer to indirectly reflect I′factor in the model, and building of composite indexes, have a good effect on establishment of rainfall models. Results show that relative deviation of the new models based on P_mer, D_mer, Z_3m is only 9.9%, while that of the traditional single rainfall factor models is 21.6%. Obviously the former is better than the latter.

Abstract:Slope soil erosion is a complex interaction of runoff scouring, slope anti-erosion effects and ground substance supplementing capacity. A field experiment of artificial runoffs was carried out over 20° slopes of barren land (CK), fish-scale pits (Treatment YLK), alfalfa land (Treatment MXCD) and straw-mulch (Treatment JGFG), separately, to study hydrodynamics of the sheet flow scouring soil particles on the slopes and analyze it using the runoff shear stress theory, unit runoff power theory and runoff kinetic energy theory, separately. Results show (1) sediment transport rate was in a good linear relationship with both runoff shear stress and runoff power, and in a good logarithm relationship with water flow energy; critical shear stress and critical power existed throughout the erosion process; (2) with increasing volumn of the flow, velocity of the flow on the slope rose rapidly, thus leading to greater flow shear stress, unit stream power and runoff kinetic energy, and hence greater soil scouring capability of the flow, and eventually aggravation of soil erosion. On the whole the three theories demonstrated their own respective features in describing soil erosion process: the runoff shear stress theory is the best to reveal soil particles detaching process in detail, while the runoff kinetic energy and power theories are fit to describe soil erosion process on slope more simply and more accurately.

Abstract:Spatial variability and distribution of soil moisture in four plantations in Xiushui County, Jiangxi Province during the hot and dry season was studied using the geostatistical method. Results show that soil moisture varied in spatial variability between the four plantations. The structural variance ratios（C/Co＋C）of the soil moisture in liquidambar formosana plantation and Cornus macrophylla-Toona sinensis mixed forest were 0.55 and 0.73, respectively, suggesting spatial correlation of a medium level. In comparison, the ratio of Firmiana simplex-Alnus cremastogyne mixed forest and Toona sinensis plantation were higher (0.84 and 0.93, respectively), suggesting spatial correlation of a high level. Soil moisture of the mixed forests was lower than of the pure plantation forests in spatial variability on both vertical and horizontal spatial dimensions, but more uniform in spatial distribution. Spatial variability of soil moisture in the 0~10 cm soil layer was greater than in both the 10~20 cm and 20~40 cm soil layers, indicating that soil moisture tend to be uniform with soil depth.

Abstract:Based on insitu observation and analysis in laboratory, mechanism of saltaccumulation in sodic saline under shallow groundwater level was explored Results show that within the study plot, 35×35m² in area, varying only 60 cm in altitude, existed four types of soils i.e. sodic saline meadow soil, shallow columnar sodic alkaline soil, white crust sodic alkaline soil and median-columnar sodic alkaline soil. Sodic saline meadow soil was distributed in depressons, and almost free of alkaline layer; white crust alkaline soil and mediancolumnar sodic alkaline soils on micro slopes and high flatland. An alkaline layer was found in 15~30 cm in depth in high flatland, with ESP (exchangeable sodium percent) being 70%. On micro slopes, ESP of soil in the surface layer was the highest, up to 75%. Groundwater table (initial level) demonstrated a three-dimension pattern, being concave in depression, thus forming a difference of 1 m in water table between depression and high flatland, which was basically leveled off within 24 hours. Variation of groundwater table in the freezing period was found to be somewhat related to formation and development of frozen soil. Groundwater table was gradually lowered during the freezing period, as a result of some groundwater moving into the frozen layer, leading to a higher moisture content therein. Soil moisture content in the surface layer of saline meadow soil increased from 20% up to 50% (over-saturated), during the period, demonstrating a significant increasing rate (p<0.05), however, it did not change much in the frozen layer of sodic alkaline soil. In the thawing period, salinity content in the surface layer of sodic alkaline soil increased quickly, especially in white crust sodic alkaline soil, by about 80%, whereas insignificant change was observed in the surface layer of saline meadow soil.

Abstract:Laboratory batch experiments were carried out to study Pb sorption desorption by four soils typical of the Yangtze River Delta in China. Thermodynamic parameters, like K°, ΔG°, ΔH° and ΔS°, were used to explain mechanism of the sorption. Results show that under the conditions of the experiment (two temperature treatments, 25±0.5℃ and 35±0.5℃) Pb sorption and desorption displayed nonlinear curves that fitted the Freundlich isotherm. The sorption K_fvalues of the four soils followed an order of Lithic Ochri-Aquic Cambosols (3 816 dm³ kg^-1) > Endogleyic Feaccumulic Stagnic Anthrosols (1 984 dm³ kg^-1) > Typic Gleyic Stagnic Anthrosols (1 030 dm³ kg^-1) > Fe-accumulic Gleyic Stagnic Anthrosols (348 dm³ kg^-1). In soils with organic matter removed, Pb sorption capacity decreased, but desorption rate increased. The K and ΔS° values increased with temperature, while ΔG° values decreased with temperature. The negative values of ΔG° suggested that Pb sorption was a spontaneous process. The positive ΔH° values indicated that Pb sorption was an endothermic process. Chemical bonding force is the major force in Pb sorption by Endogleyic Fe-accumulic Stagnic Anthrosols, Typic Gleyic Stagnic Anthrosols and Lithic Ochri-Aquic Cambosols, and Van Der Waals Force and dipole bonding force in Feaccumulic Gleyic Stagnic Anthrosols. Apparent hysteresis in Pb sorption-desorption was observed and varied from soil to soil, and the higher the pH, calcium carbonate content and equilibrium concentration, the higher the hysteresis index, which may be attributed to the formation of inner-sphere Pb sorption complex (less reversible) and precipitation of lead carbonate.

Abstract:The study on microscopic effects of interactions between “Ultrafine Particles”, ranging from 0.001 to 1 μm in diameter in soil has so far not aroused much attention due to limitation in measuring means. Conditions were discussed for application of the laser light scattering technology in the study of interactions between Ultrafine Particles in soil, from the aspects of scattering angle and soil particle density in suspension, and aggregation kinetics of soil colloidal particles and structural characteristics of the aggregates thus formed explored. Results show that (1) for the suspension of yellow earth sample, its proper scattering angle ranges from 90° to 135° and its initial particle concentration in suspension from 1.90×10^-3 g L^-1to 0.119 g L^-1; (2) in the condition that the autocorrelation function curve declines smoothly to the baseline and the scattered light intensity keeps constant with the time going on, the dynamic light scattering technique can be used to determine precisely variation of effective diameter, most probable particle size and particle size distribution during the process of aggregation of soil colloidal particles; and (3) in the system of 298 K in temperature and 90 mmol L^-1 KNO₃ in electrolyte concentration, the aggregation mechanism of the yellow earth particles in suspension was found to be the diffusion-limited cluster-cluster aggregation (DLCA) process with the dynamic light scattering technique, and its fractal dimension of the aggregates formed therein was determined to be 1.56±0.02 with the static light scattering technique.

Abstract:In this paper, variation of physic-chemical properties of aeolian sandy soil on a subsided slope in Bulianta coal mining area located at southeast Mu Us Desert were studied. Compared with the control area, the subsided area significantly experienced loss of soil moisture within the two years after subsidence (p<0.05), increase in soil porosity (p< 0.05) and decrease in bulk density and hardness of the aeolian sandy soil (p< 0.05) in the upper layer along the fringes of the subsided area 2 years after the subsidence, and decline in total N and total P (p< 0.05) in sections where cracks formed. However, total K and organic matter did not vary much (p> 0.05) in the subsided area. A scatter diagram of the values of the first 2 principal components of the sample plots in the studied area were plotted out by means of PCA, reflecting comprehensive variability of the physic-chemical properties of the sandy soil after the subsidence and quality of the soil was assessed.

Abstract:Knowledge about impacts of climatic factors on soil organic carbon (SOC) density at different scales is critical to predicting potential effect of future climate change on SOC dynamics. Based on the data of 363 forest soil profiles in Southwest China, variation of the effects of climatic factors on forest SOC density with the scale (region, province and prefecture-level city) was studied and dominant climatic factors at different scales were identified as well. Results show that the relativity of mean annual precipitation (MAP) with SOC density is decreasing with reducing scale. However, the relativity between mean annual temperature (MAT) and SOC density varies between regions, but not regularly. At the regional scale, SOC density is mainly under the joint effect of MAP and MAT. At the provincial scale, the dominant climatic factor is MAP in East Tibet, and MAT in Sichuan and Yunnan Provinces. At the city scale, similar results are found. Climatic factors can explain about 20% of the variability of SOC density at the regional scale, however, the explainability decreases with the reduction in scale.

Abstract:The variation of organic carbon content and its distribution in different particle-size fractions in oasis farmland soils with different cultivation history in Xinjiang was studied，and the influence of longterm cultivation on soil organic carbon characteristics in the northwest arid area was discussed in this paper. Soil samples were collected from native land (without cultivation，used as a control) and three typical farming land with different cultivation times，including oasis soil in Lanzhouwan，N_O31. Farm and Puhui Farm in southern and northern Xinjiang. A physical fractionation method was applied to study the content of organic carbon and its distribution in different particle-size fractions of the soil.The results were summarized as follows. (1) Cultivation practices enhanced to the accumulation of total organic carbon in soils，increased rapidly in the initial period (1～5 a)with an annual average increase about 0.5 g kg^-1, but the increase was diminished after 10 years of cultivation. (2) Cultivation practices increased the content of organic carbon in different particle-size fractions. Organic carbon in the sand fraction reached its maximum in 10 years after cultivation and tended to be stable afterwards. Organic carbon in the silt and clay increased continuously with cultivation time. (3) Ratio of particulate organic carbon (POC) and mobile organic carbon (MOC) increased rapidly with cultivation in the initial period (1～5 a)， reached its maximum in 10 years after cultivation，and started to decline afterwards. These results indicate that cultivation practices in the oasis farmland area of Xinjiang facilitates the accumulation of organic carbon in soils，particularly in the silt and clay size fractions and tends to improve the quality of organic matter as evidenced by the increased ratio of POC over MOC in the first 10 years after cultivation. However，extended cultivation for more than 10 years may cause decline of organic matter content in soil，thus affecting soil quality sustainability. Therefore，management practices need to take consideration of increasing organic matter inputs.

Abstract:Based on a 26-year-long fertilization experiment on a paddy field in the Taihu Lake Region，effects of long-term fertilization on profile distribution of soil nitrogen and C/N ratio，soil nitrogen mineralization characteristics under 10 ℃ and 30 ℃，and relationship between cumulative mineralization and effective accumulated temperature were studied. Results show: (1) Nitrogen accumulation significantly increased in the topsoil (0～20 cm)，where total nitrogen was higher in Treatments MNP (manure and fertilizer N，P)，MNPK (manure and fertilizer N，P，K)，MRN (Manure，rice straw and fertilizer N) and M0 (only manure application) than in Treatments CNP (chemical fertilizer N and P)，CNPK (Chemical fertilizer N，P and K) and CK (no fertilizer application)，however，in the 20～30 cm soil layer，it was just the contrary. And in the 40～50 cm soil layer，little difference was observed between the two groups; (2) Organic manure and straw applications may result in decrease in C/N ratio in the topsoil，where the ratio displayed an order of CNPK>MNPK，CK>M0，and was the lowest in MRN，while in the 20～50 cm soil layer，the ratio was were general higher in the organic manure treatments than in the chemical fertilizer treatments. And the subsoil in the chemical fertilizer treatments were higher soil organic matter decomposition degree; (3) Under 30℃ soil mineralization leveled off pretty quickly，but with high cumulative mineralization，while under 10℃，soil mineralization rate in the late incubation period was higher than under 30℃，but the cumulative mineralization was relatively lower. Obviously low temperature led to in decrease in soil mineralization rate. The relationship between cumulative mineralization and effective accumulated temperature well fit the effective accumulated temperature model (EATM) (p<0.01)，its mineralization constant K reflected similar mineralization potentials of the various treatments at the initial stage of mineralization. Difference between treatments in mineralization constant n reflected higher mineralization potentials in Treatments MRN，MNP，CNPK，and CNP in the late stage.

Abstract:Temporal-spatial variations of soil NH₄⁺-N and NO₃^--N exists in sand dune fixing process. Contents of soil NH₄⁺-N and NO₃^--N in sand dunes of the Tengger Desert and the Mu Us Sandy Land were measured. Results show that vertically the content of N of either form decreased with the depth along soil profiles; while horizontally，from the top to the slope and the foot of a dune，both increased gradually，but the NH₄⁺-N/NO₃^--N ratio in the depth of 20～40 cm decreased gradually. And their temporal variations were reflected in the succession series of plant community. The content of NH₄⁺-N in the soil increased gradually from the prophase to the metaphase of the series，while the content of NO₃^--N in the soil did from the metaphase to the anaphase of the series. The NH₄⁺-N/NO₃^--N ratio in the depth of 0～20 cm showed a similar trend，while that in the depth of 20～40 cm did not. Such a pattern of temporal-spatial variation of soil NH₄⁺-N and NO₃^--N was reflected in the fixing process of sand dunes，and was a result of the integrated effect of vegetation and environment，and in turn affected plant growth and vegetation dynamics.

Abstract:A pot experiment was conducted to study nitrogen accumulation and translocation quantitatively in rice plants different in cultivar and in nitrogen use efficiency (NUE) after full heading of the crop by applying ¹⁵Nfertilizer. Results show that Wuyunjing and Nanguang，two high NUE rice cultivars，were higher in grain yield than Elio，a low NUE rice cultivar，regardless of N application rates. No significant difference in dry matter accumulation and in N accumulation was observed between the rice cultivars of high NUE and of low NUE at the full heading stage and 15 days after full heading，but at the maturing stage Wuyunjing and Nanguang was 16.4% higher than Elio in dry matter accumulation，and 31% and 21% higher in N accumulation. The differences were significant. Results of the ¹⁵Nfetilizer experiment show that in Elio a portion of the ¹⁵N absorbed by the plant was translocated out of its stems and leaves，accounting for 11% of the total ¹⁵N translocated. During the growth period from full heading to maturity，the ¹⁵N translocated from the stems and leaves in Elio (2.75 mg hill^{-1) was much less than that in Wuyun (3.54 mg hill-1) and Nanguang (3.22 mg hill-1). The differences were significant. The 15N translocated from the stems and leaves of Wuyunjing and Nanguang was equal to 91% and 85%，respectively，of the N in the grains，while the 15N the plants absorbed from the soil accounted for 9% and 15%，respectively of the total N absorbed. To sum up，the rice plants do not vary much in N accumulation and N translocation until the post-full-heading stage，and the high N absorption capacity and the strong N translocation ability of the rice cultivars high in NUE can satisfy the demand of the plants for N during their grain forming stage.}

Abstract:Owning to interactions between phosphorus and aluminium in solution，the key to study effect of phosphorus on aluminum toxicity to plants is to select an appropriate method to treat phosphorus and aluminium. In this study comparison was made between two phosphorus and aluminium treatment methods. Results showed that adoption of the method based on calculation of aluminium activity demonstrated that phosphorus could alleviate aluminium toxicity to wheat，while the application of the P-Al alternate treatment method revealed that phosphorus aggravated aluminium toxicity to wheat. By directly determining concentration of inorganic monomeric aluminium in Al-P treatment solutions，it was found that the toxic aluminium concentrations of treatment solutions decreased with increasing phosphorus supply though the estimated aluminium activities by GEOCHEM were at the same levels，so that the alleviating effect of phosphorus on aluminium toxicity to plants in the calculating method might result from decreasing concentration of toxic aluminium in the solutions. The alternate treatment method can avoid P-Al interaction in the solution，thus can keep phosphorus and aluminium at the same concentration level. Moreover，long-term application of this alternate method may also eliminate the impact of phosphorus and aluminium not being treated at the same time on accuracy of the experiment. Therefore，this alternate method may probably be a relatively workable one. Under P-Al alternate treatment，phosphorus aggravating aluminium toxicity to wheat may be associated with phosphorus stimulating aluminium accumulation at root tips of wheat.

Abstract:Phosphate adsorption capacities of palygorskites modified with acid varying in concentration in P-contaminated waters different in phosphate concentration were investigated. And effect of acid modification on the mechanism of palygorskite adsorbing phosphate was also studied through pH and zeta potential measurement. Results showed that acid modification to 3%～30% increased to a varying degree the phosphate adsorption capacity of natural palygorskite，which is actually unable to adsorb any phosphate. The effect of acid modification by 3% was the highest，enabling palygorskite，applied at a rate of 1%，remove 95% of the phosphate from water of Grade V (P 0.4 mg L^-1) and 15% from water of Grade Vminus (P 1.0 mg L^-1). Acid modification also influenced pH and zeta potential of palygorskite. The former decreased from 8.6 to 3.35，and the latter fluctuated with increasing acid concentration，and peaked up to about -28.1mV when palygorskite was acid-modified by 3%. The results depicted above reveal that acid modification changes surface charge and adsorption sites of palygorskite，thus enhancing its phosphate adsorption or removing capacity.

Abstract:Phosphorus (P) is the principal pollutant contributing to eutrophication of water bodies. Contents of total P，available P and fixed P in soils of different layers (0～5 cm，5～10 cm and 10～20 cm) under different land use (sparse forest soil，sloping farmland，flat farmland and greenhouse soil) in the Baoxiang River watershed in the Dianchi Lake region were determined，and P Sorption Index (PSI) were calculated. And accumulation，distribution and sorption characteristics of P in the soils were also evaluated. Results show that total P，OlsenP and water soluble P accumulated significantly in the topsoil，especially of greenhouse soil，averaging 1.67 g kg^-1，75.9 mg kg^-1 and 27.7 mg kg^-1，respectively; and the contents of Olsen-P and water soluble P displayed a decreasing trend from the surface layer down with the depth. In respect to sorption characteristics，the contents of soil fixed P in the topsoil ranged from 68.4 mg kg^-1 to 351.2 mg kg^-1，showing little difference between soil layers under different land use，while PSI values of the soils were obviously higher in sparse forest soil and sloping farmland in the upper streams. The PSI values of the soils of the flat farmland in the middle-upper streams and the greenhouse soli in the downstream were < 30，suggesting that the potential risk of soil P loss is high.

Abstract:The morphological and nutritional characteristics on two ecotypes of reeds，upright and creeping reeds，which growing in the same soil (saline-alkali soil) and climate environment，were studied by the techniques of light microscope，scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and the methods of ions analysis. The results showed that compared with the ecotype of upright reeds，creeping reeds have higher contents of sodium，silicon and calcium，but lower content of potassium，and hard thick leaves that curled less at noon. Among the mineral ions in the plant tissues of the two ecotypes of reeds，Si was the highest in content，and followed by Na，and Ca. The distribution of sodium in the plants showed a pattern of being lower in the shoots than in the roots，and in the leaves than in the stems，while the distribution of silicon being higher in the shoots than in the roots. Analysis of the anatomical structure of reed leaves and X-ray spectrum of silicon therein revealed abundant Si on surfaces of the leaves and groups of large vacuolated bulliform cells on upper epidermis of the leaves of both upright reeds and creeping reeds. However，stretch of vascular bundle sheath cells near the upper epidermis was observed greater in the creeping reeds than in the upright one. And in the stems of the two ecotypes of reeds，Si distributed more concentratively in the part above a knot than below the knot and very little in between the knots. Si distributed evenly in the stem above the ground of the upright reeds，but concentrated on the side of the stem near the earth of the creeping reeds. All the findings above demonstrate that the morphological variation between the two ecotypes of reeds are closely related to the ion distribution. Low Na concentration and high Si concentration in leaves of the reeds contributes significantly to mitigation of damage of salt to the photosynthetic organ，and regulation of water supply and growth of the plants in the arid and salt-affected habitat.

Abstract:Micro-ecological response of three types of soils in Shandong Province to incorporation of oily sludge were studied.Soil microbial population and enzyme activity were used as indice to evaluate effects of petroleum-containing soil on soil ecosystem. Results show that the effects of petroleum pollution on soil microbial flora and soil enzyme activity varied with the type of soil. It was found that brown soil was the strongest in self-restoration capability and the least affected in microbial flora by total petroleum hydrocarbon, suggesting that it can be the first choice for phytoremediation of petroleum-polluted soil. The effect of petroleum hydrocarbon content was the most significant on actinomycete among the three microbial groups in the soil. With soil TPH content set at 500 mg kg^-1, the total count of actinomycete declined by 80%, 85% and 89% in fluvoaquic soil, cinnamon soil and brown soil, respectively. The effect of TPH on the fungi population was much less in cinnamon soil and brown soil than in fluvo-aquic soil. The variation of Amylase and unease with the TPH content in the three types of soils indicated that amylase in cinnamon soil and fluvo-aquic soil was sensitive to TPH content and could be used as a biological index in determination of petroleum contamination of soils.

Abstract:Total genomic DNAs were extracted from soil microorganisms in four soils different in fertilization treatment with the direct extraction method：The four treatments were CK (soil without fertilization)，F1 (low in fertilization level，N∶P₂O₅∶K₂O to 0.1 g kg^-1：0.075 g kg^-1∶0.15 g kg^-1)，F2 (normal in fertilization level，N∶P₂O₅∶K₂O to 0.2 g kg^-1∶0.15 g kg^-1∶0.3 g kg^-1) and F3 (excessive fertilization，N∶P₂O₅∶K₂O to 1.0 g kg^-1∶0.75 g kg^-1∶1.5 g kg^-1) 16S rDNAs of the extracted DNA were amplified using bacterial universal primers and clone libraries set up PCR-RFLP analysis was carried out with restriction endonuclease Rsa I and HhaI，and 146，133，187 and 170 types of restriction endonucleases were obtained from these samples. Statistical analysis of the data using α diversity measurement，which，revealed that the four treatments followed an decreasing order of F2 > F3 > CK > F1 in terms of bacterial diversity and species abundance，indicating that proper fertilization was conducive to bacterial diversity in soil. Variation coefficients of indices of λ，R₂， d_Ma and E between different treatments fell in the range from 12.86 % to118.9 %，especially for Simpson index λ，which was the most sensitive，and varied the sharpest. Results of sequencing and phylogenetic analysis proved clearly that，compared with CK，the fertilization treatments demonstrated obvious changes in distribution of dominant bacteria community.

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