Abstract:Content and morphotype of phyoliths was studied in a soil chronosequence consisting of five soil profiles developed from basalt ranging in age from 10 000 years to 6.12 million years in tropical Leiqiong area. It was found that 1) the content of phytoliths in the soils, ranging from 1.54 to 21.95 g kg-1, was high in the surface horizon and decreased with the depth in profile; its drop was sharp from entisols to ferrosols and less significant from ferrosols to ferralsols, and then leveled off after entering ferrosols; 2) originated mainly from poaceae and palmae, the phytoliths ranged from 5 to 130 µm in size and appeared in 12 shapes, e.g. spherical echinate, dumbbell, fan, rectangular, square, saddle, hat, rod, tapered, crenate, round and others; The phytolith samples were all > 0.5 in warmth index, indicating the study area has basically been under a warm climate since 6.12 Ma.

Abstract:Based on field investigations conducted in the 1980s of Wenquan District, Xinghai County, Qinhai Province, a large tract of permafrost on the east edge of the vast Qinghai-Tibetan Plateau (QTP), new approaches to soil mapping were explored. Based on the theory of soil forming factors and the theory for soil-landscape modeling and the screening of potential variables in soil classification, a soil-landscape model was built up using SVM coupled with various combinations of the variables, and applied to predictive soil classification of the studied area. To better verify effectiveness of the new approach, a 5-fold cross validation method was used. By comparing the outcome of the cross validation of the various variable combinations with the simulated distribution map, a set of combination of environmental variables was defined suitable for soil classification of typical permafrost area. Thus fewer samples are needed to better predict spatial distribution of the types of soils in the area.

Abstract:Raster data plays an important roll in the spatial analysis.The different raster resolution will cause the deletion of the vector information and influence the spatial analysis precision by using pedological professional knowledge-based method.In this research, the JiangXi province Yujiang region 1：50000 soil maps will be used and analyzed for the relationship between the soil type area and the raster scale in the soil taxonomy.The results turn out that the best raster scale interval for every soil types area in the great group is 0.5km, in the subgroup is 0.2km, in the soil genus and soil local type is 0.1km.The research shows that the suitable raster scale will reduce the data-density and raise the precision.So it will be more effective and more scientific to use the soil spatial data than before.

Abstract:Slope gradient is an important factor affecting raindrop splash erosion. Hence its effect was investigated using soil trays simulating nine slope gradients (9%, 18%, 27%, 36%, 47%, 58%, 70%, 84%, and 100%), and each soil tray was 0.5m × 0.5m × 0.1m (horizontal length × width × depth) in dimension, containing loamy soil, collected from Yanqing, Beijing. All the treatments were subjected to a simulated rainfall with a constant intensity of 67 mm h^-1 for 1 hour. Specially designed samplers were used to partition total splash into directional components (e.g. upslope, downslope, and lateral). Results indicate that splash erosion occurred in the following three patterns: (1) the rate was low prior to the generation of runoff, peaked rapidly at the beginning of runoff, decreased gradually and leveled off; (2) the rate was high prior to the generation of runoff and dropped rapidly after runoff was generated and then leveled off at a certain rate; or (3) the rate did not show any obvious fluctuation during the rainfall event. In all the treatments, the upward raindrop splash erosion rate was always lowest and the downward one was the highest. And the downward splash and sideward splash were negatively related to slope gradient and the relationship could be fit with a linear or exponential function. The downward splash erosion varied more obviously than lateral and upslope splash erosion, which indicates that downslope splash erosion is more significantly affected by slope gradient. The downward splash erosion, total splash detachment, and net splash transport increased initially with rising slope, and then decreased at the critical slope gradient, 35° (70%), all showing linear relationships.

Abstract:On the basis of accounting results of agricultural production capacity in Guangdong Province, the paper analyzed the spatial patterns of natural productivity use potential(future productivity potential) and reality productivity use potential(short-term productivity potential) under the five Typical Areas in Guangdong Province, and according to the cultivated land gradation results and factor differentials & correlation coefficient of the participating factors ,it explored the main impact factors for promoting the production capacity potential of typical areas in near future. The results showed that the most high-value areas of use intensity and the minimum value areas of use potential in the Northern of Guangdong province and in the Chaozhou-Shantou region, especially in latter region where there was hardly any potential in some places, and meanwhile the more promoting potentials area was in Luichow peninsula region,Central-south and Southwest of Guangdong province. Therefore, ensuring probability of agricultural irrigation was an important way to increase cultivated land production capacity in the future in Luichow peninsula. Renovating farmland infrastructure was a main way to increase production capacity in central south and southwest of Guangdong province, and improving the soil pH and increasing soil fertility were also the effective ways in above regions; it could increase cultivated land production capacity through improving organic content, agricultural irrigation and farmland slope in the northern of Guangdong province;Production capacity could be partly increased by improving salinification along the coast in the Chaozhou-Shantou region .

Abstract:Partition the anthropogenic component from heavy metal accumulations is significant for modeling heavy metal concentration processes caused by intensive human activities. This paper measured urban sprawl of Yixing city, China since 1949 and evaluated accumulations of Cd, Cu, Pb and Zn affect by urban sprawl. An approach, content partition, was developed to partition total contents of heavy metal into three components: tendency，background and residual. Results showed that during the past three decades, Yixing city has grown fast, with an average rate of 71ha per year. Heavy metal contents increased with city growing old, which suggested that heavy metal concentration process has been modified by urban sprawl. Content partition method could effectually explain the control facts of heavy metal accumulation under the rapid urbanization area. Tendency components of Cd, Cu, Pb and Zn counted 16.6、18.4、33.22 and 2.7 %to the total contents, respectively. The spatial patters of tendency components of Cd, Cu, Pb and Zn show clear decrease gradient in the direction of urban-rural. Background components were expressed quantitatively by multi-regression equations. Finally, Flux equations were estimated to show the spatial distribution pattern of accumulation flux, which is useful for modeling the heavy metal accumulation process on the impact of human activities.

Abstract:The research on spatial variability, accumulation and transfer of soil mercury (Hg) has great reference values to soil utilization, environmental assessment and polluted soil remediation. Mercury in the soil, rice and atmospheric deposition in an area with fast developing economy in the South Jiangsu was analyzed. It was found that on average, the soil total Hg was 1 345 μg kg^-1, available (HCl-extractable or HCl-Hg) 51 μg kg^-1, Hg in rice 20 μg kg^-1 and Hg in atmospheric deposition 5.13 g km^-2 30d^-1. Spatially, high Hg concentrations in soil and rice were found mainly in places closely around the town, and the concentration decreased exponentially with the distance of the sampling site from the town. Atmospheric Hg deposition was found low in variability within the whole study area. Mercury in the soil accumulated mainly in the 0 ~ 20 cm soil horizon, however, Hg accumulation could still be found at 60 cm in depth. The percentages of soil Hg in mobile and semi-mobile state to total Hg did not vary much in the whole soil profile. Obvious soil Hg accumulation observed in the studied area led to higher Hg concentrations in rice. The concentration in quite a number of sampling sites already exceeded the second grade criterion of the National Standard for Soil Environmental Quality (300 μg kg^-1) and the National Food Safety Standard (20 μg kg^-1), and would bring about hazard to the environment quality and human health. The fact that balance is maintained between the soil conditions and Hg accumulation in soil and the low atmospheric Hg deposition indicate that the ongoing accumulation is not as significant. Measures such as remediation of the polluted soil or rotation of low-Hg-uptake crop species should be taken to reduce soil Hg or to inhibit Hg uptake by crops, and hence to achieve the target of environmental management.

Abstract:The ubiquity of phthalate esters has been frequently reported in agricultural soils in China. Samples of soil and plastic film were collected in a plastic greenhouse field cultured with vegetables from suburb of Hangzhou city, Zhejiang Province. The results indicated that contamination of PAEs was occurred in the soil of local vegetable field and the degree of PAEs contamination was comparable to that found in most of other study areas in China. Content of PAEs in the plastic film have a positive impact on the content of PAEs in soil. Soil covered with aged plastic film or with the black film was observed containing high content of PAEs. Therefore, reduction of the aged plastic film residue in soil is a feasible way to decrease PAEs contamination in soil. No significantly difference was found among the different covering types (shed or mantled) of plastic film in present study. Significant positive correlation has been obtained between the content of PAEs and that of organic matter in soil, which is presumed that soil organic matter would be an important effects on the environmental fate of PAEs, in particular for the higher molecular PAEs such as DEHP.

Abstract:To provided the theory basis for the reasonable exploitation and sustainable utilization of saline-sodic soil with shallow water table, soil water potential was observed by tensiometer and, according to different growth periods of Fructus Lyeii, soil above water table was sampled in each layer to study the annual dynamic changers of soil salt. The results showed that water was kept infiltrating radially from the dripper till the next irrigation; during the rainy season, rainwater moved from the upper layer to the deeper and slowed down while water table rose up; soil water than moved from the middle of the bed to the slope. Salt movement was obviously affected by water movement and it can be divided into five stages in a year: evaporation in spring-salt accumulated stage; leaching by irrigation-salt stabilized stage; leaching by rainfall-desalinized stage; evaporation in autumn-salt accumulated stage and relatively stable stage in winter. At the experiment field, after mulch-drip irrigation for a year, salt accumulated insignificantly and EC1:5 of the bed varied from 1.64 dS ^-m to 1.69 dS ^-m. The distribution of salt in transect indicated that soil salt was regulated by mulch-drip irrigation and suitable soil environment was provided for root growth, so the saline-sodic soil with shallow water table can be utilized by mulch-drip irrigation with saline water.

Abstract:Soil water retention curves in low suction range during the evaporation process were determined by use of tensiometers to study the effects of three straw treating manners (i.e. cut, aminated or mixed with inorganic soil amendment) on saturated soil water content, soil water retention and supply capacities as well as the soil dehydration rate in the early stage of drought process. Results show that incorporation of finely cut straws into soil enhanced saturated soil water content, improving soil water retention and supply capacities, and the finely cut and aminated straws were more effective than the long cut straws. The dehydration rate of the soil in the early stage of drought in low suction range increased when the straws (both finely cut or long cut) were applied in soil, while decreased with the aminated straws or straws mixed with inorganic soil amendment, and more soil available water conserved. The results provide useful information for more efficient straw-incorporation method to improve the soil water retention capacity.

Abstract:Autoclaving sterilization, which was usually used for soil sterilization, was generally to evaluate the effect of autochthonous microorganisms on the study purpose. But the physical, chemical and microbiological properties of soil samples which were autoclaved may changed during the sterilization process, and then led to the effect of autochthonous microorganisms was covered up. Basic propertie, including organic matter(OM), specific surface area (SSA), pH, cation-exchange capacity (CEC), free iron/ aluminium oxides(Fed，Ald) and zero point of charge (ZPC), of the eight typical soils(Usti-Sandic primosols, Usti-Alluvic Primosols, Hapli-Stagnic Anthrosols, Gleyi-Stagnic Anthrosols, Ferri-Udic cambosols, Argi-Argiudic Ferrosols, Alliti-Argiudic Ferrosols, Rhodi-Udic Ferralosols) in China were analysed in this study. The value of bacteria, fungi, and actinomycetes were also analysed to determine the effect of the sterilization treatment. The results showed that the OM was not affected by autoclaving excepted for Usti-Sandic primosol and Ferri-Udic cambosols. The pH varied obviously in the soils which had lower pH and higher organic matter content, while changed little in the soils with higher pH and lower organic matter content. The SSA of all the studied soil decreased significantly after sterilization, while there was no significant change for CEC and Fed，Ald between unsterilized and sterilized soils. The zero point of charge (ZPC) of the four variable charge soils was titrated, and the results showed that ZPC of the Ferri-Udic cambosols was decreased by autoclaving, while ZPC of the other three soils was not changed. Although the value of bacteria, fungi, and actinomycetes were decreased significantly after autoclaving, the ideal condition of disappearance of all was not achieved. It is possible that more phenomena and mechanism in soil autoclaving are required to validate the finding.

Abstract:Effect of TiO₂ nanoparticles on transport of Cu in various soils was studied in a leaching experiment. It was found that TiO₂-nanoparticle-colloids-associated Cu was the sole and main form transporting in sand and sandy-loam soils relatively low in soil organic matter and high in cation exchange capacity, respectively. The presence of TiO₂ nanoparticles actually increased the movability of Cu by 8 432 and 32 times in sand and sandy-loam soils, respectively. However, this enhanced phenomenon was significantly reduced in silt-sandy-loam and loam soils. In silt-sandy-loam soil, only 1.35% of Cu was transported in TiO₂-nanoparticle-associated form. In loam soil, soluble Cu was the sole form in transportation and TiO₂ nanoparticles were no longer the carrier. During the transport through soils, the previously adsorbed Cu on TiO₂ nanoparticles were effectively stripped off and extent of the stripping depended on soil properties. Soil organic matter demonstrated a strong tendency to get into chelation with Cu, therefore soil organic matter is an important factor that determines desorption of Cu from TiO₂ nanoparticles. The higher the content of soil organic matter in the soil, the easier for it to compete for Cu adsorption with TiO₂ nanoparticles and the higher the Cu desorption rate in the soil.

Abstract:Effects of ionic strength on adsorption and desorption of phosphate in variable charge soils were investigated with batch method. Results indicate that when pH was higher than 3.7 or 4.0, the amount of phosphate adsorbed by red soil and latosol increased with increasing ionic strength, and when pH was lower a reverse trend was observed for both soils. Electrolyte affected the adsorption of phosphate by the soils through its effect on electrostatic potential of the ionic specific adsorption plane, which existed between Stern layer and diffuse layer. Zeta potential of soil colloids suggested that when pH was greater than the isoelectric point (IEP), the potential in the adsorption plane was negative and became less negative with increasing ionic strength, thus allowing increase in phosphate adsorption by the soils; when pH was less than the IEP of soil colloids, the potential was positive and decreased with increasing ionic strength, thus decreasing phosphate adsorption by the soils. The results of desorption of pre-adsorbed phosphate indicated that the amount of phosphate desorbed by deionized water was greater than that by 0.1 mol L^-1 NaNO₃. This was also ascribed to the effect of ionic strength on potential in the adsorption plane.

Abstract:To explore short-term effects of acid rain on soil respiration in three zonal evergreen broadleaf tree sapling-soil systems, i.e. Paramecia latungensis (PL), Cyclobalanopsis glauca (CG) and Elaeocarpus glabripetalus (EG), typical of Zhejiang Province, where acid rain pollution has been severe for a long time, showers of acid rain different in pH (2.5, 4.0 and 5.6 separately) were simulated. Soil carbon effluxes (E) of the three sapling stands were monitored in various growing seasons. (1) When the stands were stressed by severe acid rain (pH 2.5), E decreased significantly in all seasons in the PL stand; dropped in winter but rose in spring and summer in the CG stand compared to the control, and varied sharply only in winter in the EG stand. the effect of acid rain moderate in pH (4.0) was significant in the PL stand where E was lower than the control in all the two years except for in August 2007, when E was 25.3% higher than the control; in the CG stand, E dropped well below the control in December 2006 and rose up to 1.96 μmol m^-2 s^-1 in August 2007; and in the EG stand, E decreased by 18.0% only in November 2007. (2) the effect of acid rain on E was not significant in the PL and EG stands at the growing period-time scale. Although in the CG stand, E increased by 87.8% and 11.1% respectively, by exposure to severe acid rain and moderate acid rain, only the effect of severe acid rain was significant. (3) The leading factors affecting soil respiration were soil temperature and acid rain in the PL and CG stands; soil temperature in the EG stand; and acid rain in the CG stand, where a negative relationship of E with pH of acid rain was observed.

Abstract:Net photosynthetic rate, annual carbon fixation, and total carbon fixation of cyanobacterial crusts in relation to history of artificial revegetation (16, 21, 27, 44 and 52 years) were investigated at Shapotou, the southeast edge of the Tengger desert, and their relationships with biological parameters (coverage and biomass) of the cyanobacterial crusts, and organic carbon content in the surface soil (0~3cm) were also analyzed. Results show 1) the maximum net photosynthetic rate of the crusts profoundly increased with the history of revegetation, from 1.63 μmol m^-2 s^-1 in the area revegetated for 16 years to 2.81 μmol m^-2 s^-1 in the area revegetated for 52 years, showing significant positive relationship with coverage and biomass of the crusts; 2) annual carbon fixation increased exponentially with the history of revegetation, from 0.2 g m^-2 a^-1 C in the area revegetated for 16 years to 2.78 g m^-2 a^-1 in the area revegetated for 52 years; and 3) the total carbon fixation of the crusts experienced two phases of variation after the revegetation; in the first phase (from 16a to 27a) low in total carbon fixation, in the range from 2.2～6.2 g m^-2 C, and in the second phase (after 44 a) high in total carbon fixation reaching 23.9 g m^-2 C; showing a linear positive relationship with organic carbon content in the surface soil. The findings indicate that the maturity of cyanobacterial crusts improved along with the succession of the artificial revegetation, cyanobacterial crusts are getting more and more mature and increasing significantly in photosynthetic carbon fixation capacity, which is conducive to accumulation of soil organic carbon in arid soils.

Abstract:Pedogenic carbonates (PCs) are important components of the soil carbon (SC) pools in arid and semi-arid regions, and the pool of PCs is 2 ~ 5 times bigger than that of soil organic carbon therein. Formation and turnover of the PCs plays a significant role in balance of soil carbon in the regions. Soil samples were collected from a Stipa breviflora dominated desert steppe in Inner Mongolia for analysis of content and δ¹³C of soil carbonates，δ¹³C of CO₂ and δ¹³C of parent rocks, hence to explore effect of formation and turnover of pedogenic carbonates on sequestration of CO₂ and calculate the amount of CO₂ sequestrated. Results show that the δ13C value of PCs was determined mainly by the composition of carbonate isotopes of soil CO₂ and could be figured out with the aid of the δ¹³C value of soil CO₂. Fractionation of the SC in the study area revealed that PCs accounted for 83.6%, 65.4%, 41.7% and 17.4% in the soil layers of 40-50, 50-60, 60-80 and 80-100 cm, respectively. With the help of δ13C values and the principles in chemical balance, the amount of CO₂ sequestrated during the process of PCs formation and turnover was worked out, being 38.3, 39.2, 25.1 and 9.2 g kg ^-1 soil in these layers, respectively.

Abstract:In the consecutive 2-year field study (2007~2008), we took soil samples at four different cotton growth stages, namely, seedling, budding, boll forming and boll opening stages from cotton fields that had been planted with Cry1Ac cottons separately since 1999, 2002 and 2006, and collected soil meso- and microarthropodas in the samples with the modified Tullgren method, to monitor environmental impact of long-term cultivation of transgenic insect-resistant cotton in field conditions. A total of 12 taxonomic groups of soil meso- and microarthropods were obtained from soil samples collected in 8 times during the 2 years and could be further sorted into 7 classes, and 11 orders under arthropodas phyla. Collembola, Opisthopora and Acarina were the dominant groups and Symphyla, Isoptera, Hemiptera, Diplura, Coleoptera and Homoptera were the common groups in the soil. The Generalized Linear Mixed Model (GLMM) analysis of the 2-year data on soil arthropods shows that no significant difference was found between cotton fields different in cultivation age in individual number and the community diversity indices of the soil meso- and microarthropodas of the main soil arthropod groups, but significant seasonal variation was observed of the individual numbers and the diversity indices of the main soil meso- and microarthropodas. The Principal Component Analysis suggested that Collembola, Opisthopora and Acarina were relatively higher in value and can be cited as important indicator organisms to monitor environmental impacts of transgenic plants in the future in this region.

Abstract:Total soil microbial DNA was directly extracted from soils of farmland (F), tea garden (T) and natural forest (G) at the Taoyuan Agro-ecosystem Research Station and soil bacteria community structures of the soils were analyzed with the technology of T-RFLP and RT-PCR amplified 16S rRNA gene fragments. It was found that the bacterial diversity index or Shannon index followed the order of farmland > tea garden > natural forest (p<0.05), while the population of soil bacteria did the order of tea garden > natural forest > farmland (p<0.05)，and the highest (tea garden) was 8.76 times as much as the lowest (farmland). The analysis based on the similarity values using Jaccard’s coefficient and T-RFLP profiles by PAT T-RFLP program showed that soil bacteria community structure was significantly different between farmland and the other two, but was quite similar between tea garden and natural forest. The analysis of chemical properties of the soils showed that Olsen-P, available K and SOC were the major factors distinctly affecting soil bacteria community structures in those soils under different land-use. Taking economy and ecology into account, tea garden should be a sustainable land use pattern for upland red soil in China.

Abstract:Litter decomposition is the key process in nutrient recycling in the terrestrial ecosystem. A clear knowledge about how litter diversity affects composition and abundance of the soil microbial community and then potentially changes the microbiological mechanism of litter decomposition will help understand the relationship between biological diversity and functions of a forest ecosystem. A pot experiment was carried out to compare mixed litters from massion pine, slash pine, white oak and blue Japanese oak, which are all typical species of the hilly red soil regions in South China, with litter of conifer leaves only in effect of their decomposition on soil microbial community structure with the PLFA method. Results show that (1) the mixed litter treatment was lower in total PLFA, in relative abundance of fungi and in fungi/bacteria of the soil microbial community, but higher in relative abundance of bacteria and actinomyces than the single litter treatment. And the difference in soil microbial biomass between the treatments was contributed mainly by fungi; (2) The principal component analysis (PCA) of the PLFA data demonstrated that mixed litter treatment differed significantly from the single litter treatment in soil microbial community structure. Principal component one (PC1) explained 65.74% and 89.63% of the variation respectively in the two decomposition periods (9 and 18 months). PC1 consisted mainly of fatty acids of 18:2ω6,9、18:1ω9c, 17:0 and 10Me18:0; (3) Soil microbial community structure was affected by initial carbon-nitrogen ratio (C/N) and lignin-nitrogen ratio (lignin/N) of the litter, which were negatively related to relative the abundance of bacteria, but positively to the relative abundance of fungi and fungi/bacteria in the soil microbial community. Decompositions of mixed conifer-broadleaved leaf litters provided a more favorable microenvironment for decomposers by changing the chemical composition of the litters such as carbon-nitrogen ratio and lignin-nitrogen ratio.

Abstract:Continuously cropping system of cash crops often destroyed soil microbial ecology with soilborn pathogens enriched but the number as well as species of beneficial strains decreased, leading to a shift from bacterial dominant type to fungi dominant one. Therefore, pathogens can more easily invade plant roots resulting in severe plant disease such as Fusarium wilt. Application of bio-organic fertilizers can reconstruct soil microbial community structure, consequently suppressing soilborne diseases. Advances on changes of microbial amount and diversity after continuously cropping and also the recovery tendency of soil microbial amount and diversity by applying bio-organic fertilizer were summarized. Furthermore, 454 pyrosequencing was introduced as a powerful tool by comparison with the traditional methods to analyze the microbial structure in the future.

Abstract:Methane is a major greenhouse gas, which contributes estimatedly 20% to global warming. Microbially mediated anaerobic oxidation of methane (AOM) is an important way to reduce methane emission in nature. According to different coupling reactions, AOM can be divided into two types, Sulphate-dependent anaerobic methane oxidation（SAMO）and Denitrification-dependent anaerobic methane oxidation (DAMO). SO₄^2- and NO₂^-/NO₃^- function as their terminal electron acceptors, separately. This review summarizes types of AOM and microorganisms involved, elaborates mechanisms of the AOMs, and discusses orientation of the future research and prospects of the application of AOM.

Abstract:Researches and development of environmental mineral materials (including natural mineral materials, modified mineral materials, synthetic mineral materials, and et al.) used to remedy soils polluted by heavy metals, organic pollutants and virus was reviewed. A range of environmental clean-up technologies has been developed, using environmental mineral materials to remedy contaminated soil, e.g. the use of clay to remedy polluted soil, and of iron and manganese oxides to deal with soils polluted with heavy metal and organic pollutant. In remediation of soils polluted with heavy metals, mineral apatite and metallic minerals containing elements with changeable valence are used as reductant or oxidant to react with pollutants. And further research and development of the materials based on cost/effeciency, mechanism, application and modification of mineral materials and relationship between soil nutrients and environmental mineral materials are suggested.

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