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1.
上海地区水稻土氮素矿化模拟   总被引：1，自引：0，他引：1  
Three types of paddy soils, derived from granite, Quaternary red clay and basalt, respectively, were selected to study the effects of Fe and Mn in paddy soils on methane production and emission through pot and incubation experiments. The results indicated that the difference of Fe and Mn in paddy soils was one of the important factors causing obvious differences in methane emission from different soil types. Soil Fe and Mn affecting methane emission from the paddy soils was likely through affecting soil Eh and forming Fe and Mn plaques on rice roots. Different rates and valences of added Fe and Mn significantly affected methane production from paddy soils. Therefore, this study enhanced understanding of processes controlling methane emission from paddy soils and may help to improve modeling and estimating regional and global methane emission from paddy soils.  相似文献   

2.
土地利用史对水田甲烷的排放和甲烷植物的影响   总被引：1，自引：1，他引：1  
The characteristics of methane emission were compared among six types of upland and paddy soils developed from different materials with distinct physical and chemical properties after planting rice.The fluxes of methane emission in submerged soils from the upland were obviously lower than those from the paddy rice field.The flux of methane emission in the paddy soil developed from fluvo-aquic soil was the largest among all the types of soils.Planting of rice was heplful to emission of methane in soils.The amounts of various groups of methanogenic flora were conformed with the differences among the fluxes of methane emission in various types of soils.Methane formation was observed in each type of air-dried soils stored for a long time after addition of water and incubation at 35℃.  相似文献   

3.
The accurate quantification and source partitioning of CO2 emitted from carbonate (i.e., Haplustalf) and non-carbonate (i.e., Hapludult) soils are critically important for understanding terrestrial carbon (C) cycling. The two main methods to capture CO2 released from soils are the alkali trap method and the direct gas sampling method. A 25-d laboratory incubation experiment was conducted to compare the efficacies of these two methods to analyze CO2 emissions from the non-carbonate and carbonate-rich soils. An isotopic fraction was introduced into the calculations to determine the impacts on partitioning of the sources of CO2 into soil organic carbon (SOC) and soil inorganic carbon (SIC) and into C3 and/or C4 plant-derived SOC. The results indicated that CO2 emissions from the non-carbonate soil measured using the alkali trap and gas sampling methods were not significantly different. For the carbonate-rich soil, the CO2 emission measured using the alkali trap method was significantly higher than that measured using the gas sampling method from the 14th day of incubation onwards. Although SOC and SIC each accounted for about 50% of total soil C in the carbonate-rich soil, SOC decomposition contributed 57%–72% of the total CO2 emitted. For both non-carbonate and carbonate-rich soils, the SOC derived from C4 plants decomposed faster than that originated from C3 plants. We propose that for carbonate soil, CO2 emission may be overestimated using the alkali trap method because of decreasing CO2 pressure within the incubation jar, but underestimated using the direct gas sampling method. The gas sampling interval and ambient air may be important sources of error, and steps should be taken to mitigate errors related to these factors in soil incubation and CO2 quantification studies.  相似文献   

4.
中国自然湿地甲烷排放: 1995-2004年研究总结   总被引：2，自引：0，他引：2  
From studies undertaken during 1995-2004, annual budgets of CH4 emissions from natural wetlands and its temporal and spatial variations were examined throughout China, and various factors influencing CH4 emissions were also evaluated. The seasonal variation in CH4 emissions that increased with increasing plant growth reached its peak in August;decrease in the emissions was found in freshwater marshes but not in peatlands. Emissions were mainly controlled by temperature and depth of standing water. Low CH4 emissions at the early plant growing stages were not because of deficiency of organic C for CH4 production but because of low temperatures. Low temperatures not only reduced CH4 production but also stimulated CH4 oxidation by lowering the activity of other aerobic microbes which left more O2 in the rhizosphere for methanotrophs. Low summer temperatures (below 20 ℃) in the Qinghai-Tibetan Plateau lowered CH4 production and CH4 emission resulting in little or no seasonal variation of emissions. Diel and spatial variation in CH4 emissions depended on plant species. For plants that transport CH4 using the pressure-driven convective through-flow mechanism, diel variation in CH4 emissions was governed by diel variation of solar energy load (that produces temperature and vapor pressure differences within various plant tissues) and stomatal conductance. For plants that transport gases using the molecular diffusion mechanism only, the diel variation of CH4 emissions was because of differences in the magnitude of O2 produced through photosynthesis and then delivered into the rhizomes and/or rhizosphere for CH4 oxidation. Emergent plants could transport more CH4 than submerged plants because the former transport CH4 directly into the atmosphere rather than into water as do submerged plants where CH4 can be further be oxidized during its diffusion from water to the atmosphere. Emergent plants with high gas transport capacity could not only transport more CH4 into the atmosphere but also live in deeper water, which in turn would inundate more plant litter, resulting in increased availability of C for CH4 production. Annual CH4 emission from natural wetlands in China was estimated to be 1.76 Tg, up to 1.17 Tg of which was emitted from freshwater marshes. CH4 emission from freshwater marshes mainly occurred during the growing season and less than 8% was released during the freeze-thawing period despite the fact that thawing efficiently released CH4 fixed in ice column into the atmosphere.  相似文献   

5.
Biological characteristics of methane emission were compared among Oryza saliva, Panicum crus-galli and Cyperus di加rmis grown on paddy soil. The order of the amounts of methane emitted was P. crus-galli>0. saliva>C. difjormis, with the former two 11 and 8 times as much as that of the latter, respectively. And it was just opposite to that of the methane-forn>ing activities of roots of the three plants. The diurnal changes of methane emission of the three plants were relatively consistent with valleys during 11:00-14:00 and midnight and peaks during 8:00-11:00, 14:00-20:00 and about 5:00 early morning. The methanogenic activites in rhizospheric soils were higher than those in nonrhizospheric soils with P. crus-galli and O. saliva, but not with C. diffbrmis. The pathways of methane release of P. crusyalli and 0. saliva were probably through the top gaps near the junctions of nodal plate and leaf sheath; however in C. di fformis top Raps from which methane could escape into atmosphere were not found.  相似文献   

6.
酸雨对土壤有机碳氮潜在矿化的影响   总被引：16，自引：0，他引：16  
Acid rain is a serious environmental problem worldwide. In this study, a pot experiment using forest soils planted with the seedlings of four woody species was performed with weekly treatments of pH 4.40, 4.00, 3.52, and 3.05 simulated acid rain （SAR） for 42 months compared to a control ofpH 5.00 lake water. The cumulative amounts of C and N mineralization in the five treated soils were determined after incubation at 25 ℃ for 65 d to examine the effects of SAR treatments. For all five treatments, cumulative CO2-C production ranged from 20.24 to 27.81 mg kg^-1 dry soil, net production of available N from 17.37 to 48.95 mg kg^-1 dry soil, and net production of NO3-N from 9.09 to 46.23 mg kg^-1 dry soil. SAR treatments generally enhanced the emission of CO2-C from the soils; however, SAR with pH 3.05 inhibited the emission. SAR treatments decreased the net production of available N and NO3-N. The cumulative CH4 and N2O productions from the soils increased with increasing amount of simulated acid rain. The cumulative CO2-C production and the net production of available N of the soil under Acmena acuminatissima were significantly higher （P 〈 0.05） than those under Schima superba and Cryptocarya concinna. The mineralization of soil organic C was related to the contents of soil organic C and N, but was not related to soil pH. However, the overall effect of acid rain on the storage of soil organic matter and the cycling of important nutrients depended on the amount of acid deposition and the types of forests.  相似文献   

7.
Nine soils with distinct properties and Se levels were selected to test a fractionation procedure of soil Se based on sequential extraction. Soil Se was fractionated into readily available Se (fraction Ⅰ, extracted by 0.5 M NaHCO3), slowly available Se (fraction Ⅱ, extracted by 0.1 M NaOH-0.1 M Na4P2O7), amorphous oxide-occluded Se (fraction Ⅲ, extracted by acid ammonium oxalate), free oxide-occluded Se (fraction Ⅵ, extracted by dithionite-citrate-bicarbonate buffer solution) and residual Se (fraction Ⅴ, determined by HNO3-HClO4 digestion of the final soil residue). The recovery of soil Se (the sum of all fractions over total soil Se determined independently) by this procedure was from 88.1% to 110.9%, mean 99.2%±6.4% for the test soils. The sum of fractions Ⅰ and Ⅱ, provided a good measure of available Se in soils and the percentage of fraction Ⅰ plus Ⅱ over the total soil Se, tentatively defined as Se availability index, could be used to indicate soil Se status and predict Se deficiency.  相似文献   

8.
Rice planting (RP) is significant to methane (CH4) emissions from paddy fields, but its effect on the relative contribution of the acetoclastic methanogenesis to total CH4 production (Fac) and the fraction of CH4 oxidized (Fox) is poorly understood. To quantify the responses of the Fac and Fox to RP, we investigated CH4 fluxes, CH4 production and oxidation potentials, dissolved CH4 concentrations, and their stable carbon isotopes in a flooded paddy soil. The mcrA and pmoA gene copies were also determined by quantitative polymerase chain reaction (qPCR). Compared with the unplanted soil (control, CK), the seasonal CH4 emissions from the planted soil were significantly enhanced, 13.6 times, resulting in large decreases in the CH4 concentrations in the soil solution. This indicated that much more CH4 was released into the atmosphere by the RP than was stored in the soils. Acetoclastic methanogenesis became more important from the tillering stage (TS) to the ripening stage (RS) for the CK, with Fac values increased from 17%–20% to 46%–55%. With RP, the Fac values were enhanced by 10%–20%, and it significantly increased the copy numbers of the mcrA gene at the four rice stages (TS, booting stage (BS), grain-filling stage (GS), and RS). Furthermore, the effect of the RP on the abundance of the mcrA gene was highly concurrent with the effect on the Fac values. At the TS, the Fox values at the soil-water interface were around 50%–75% for the CK, being 15%–20% lower than those of the RP in the rhizosphere. It increased to 65%–100% at the GS, but was reduced by 20%–30% after the RP. These differences might be because the copy numbers of the pmoA gene were significantly raised at the TS while lowered at the GS by the RP. This was further demonstrated by the strong correlations between the effect of the RP on the abundance of the pmoA gene and the effect on the Fox values. These findings suggest that RP markedly impacts on the abundances of the mcrA and pmoA genes, affecting the pathway of CH4 production and the fraction of CH4 oxidization, respectively.  相似文献   

9.
The zonal soils in the south subtropical zone of Fujian are lateritic red soils.A type of dark clayey soils.which was historically defined as lateritic red soils,derived from weathering products of the basalts was indicated by the investigation results to be markedly different from lateritic red soils and could be classified as Typical Hapluderts.They are distributed as complex zones with the lateritic red soils.The vertisols in this region were considered as a type of lithogenic soils and the vertic characteristics delay and inhibit the soils from allitic processes and then formed an independent soil type.The vertisols have higher fertility and better agricultural production characters than the lateritic red soils.The different ways in utilizing and managing these soils according to their properties and fertility are also suggested.  相似文献   

10.
A filed experiment with an early rice-late rice rotation was carried out on a paddy soil derived from red soil in the southern part of Zhejing Province to elucidate the effect of excess P application on some important characteristics of soil properies and its relation to nutrient status and grain yields of rice crops.The experimental results indicated that adequate fertilizer P(15 kg P hm^-2)could increase the content of soil available P at the tillering stage of early rice,the contents of N,P and K in the shoots of early rice at primary growth stages,and the grain yield of early rice by increasing valid ears per hectare and weight per thousand grains,which,was mainly related to the higher contents of reduced,non-reduced and total sugar in the shoot at the heading stage, And early rice supplied with excessive P could not yield more than that applied with adequate, P de to the reduction in the valid grain percentage and weight per thousead grains. In addition,one-time excess P supply at a rate as high as 90 kg P hm^-2 could not improve the soil P fertility in case the soil available P content was lower than the initial(3.74mg kg^-1 soil) after an early rice-late rice rotaion,and made a decline in the grain yield increased by per kilogram fertilzer P.Thus,one-time excess P supply should not be adopted for soils with a large P fixation capacity like the paddy soils derived from red soils.  相似文献   

11.
Some mechanistic models have been proposed to predict the No3^- concentrations in the soil solution at root surface and the NO3-N uptake by plants,but all these relatively effective non-steady state models have not yet been verified by and soil culture experiment.In the present study,a mathematical model based on the nutrient transport to the roots,root length and root uptake kinetics as well as taking account of the inter-root competition was used for calculation,and soil culture experiments with rice,wheat and rape plants grown on alkali,neutral and acid soils in rhizoboxes with nylon screen as a isolator were carried out to evaluate the prediction ability of the model through comparing the measured NO3-concentrations at root surface and N uptake with the calculated values.Whether the inter-root competition for nutrients was accounted for in the model was of less importance to the calculated N uptake but could induce significant changes in the relative concentrations of NO3^- at root surface.For the three soils and crops,the measured NO3-N uptake agreed well with the calculated one,and the calculated relative concentrations at root surface were approximate to the measured values.But an appropriate rectification for some conditions is necessary when the plant uptake parameter obtained in solution culture experiment is applied to soil culture.In contrast with the present non-steady state model,the predicted relative concentrations,which show an accumulation,by the Phillips‘ steady-state model were distinct from the measured values which show a depletion,indicating that the present model has a better prediction ability than the steady-state model.  相似文献   

12.
中国太湖地区水稻田甲烷排放的估算   总被引：13，自引：0，他引：13  
Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closed chamber method in 1992 and 1993 and CH4 emission from this region (total area of paddy soils was about 1.88 million hectares,of which 0.63 million hectares are distibuted in the south of Jiangsu province) was estimated on the basis of the meam CH4 fluxes observed.The results showed that the mean CH4 flaxes from late rice and single cropping rice field were quite similar under the prevailing cultivation practices in the region,being around 5 mg CH4/m^2/h(4.31-5.31mg CH4/m^2/h for various cultivars of the late rice and 3.20-6.22mg CH4/m^2/h for various treatments of the single cropping rice).Total CH4 emission from paddy soils in the region was estimated to e 0.185-0.359 Tg CH4 per year.Continuously flooding the soil with a water layer till ripening caused higher mean CH4 flux;and addition of nitrification inhibitor(thiourea) stimulated CH4 emission.There was no simple repationship between CH4 flux and either soil temperature or soil Eh.  相似文献   

13.
Xiong  L. M.  Lu  R. K. 《土壤圈》1991,1(1):63-72
Phosphate was found to have neither influence on Cd transformation nor effect on plant Cd uptake in three Cd-amended upland soils.However,on submerged red earth,high phosphate dressing inhibited the transformation of Cd from exchangeable fraction to other lower-available ones.Cadmium uptake by rice plants increased simultaneously with increasing phosphate supply though plant resistance to Cd also increased at high phosphate level.Application of phosphate as an amendment for Cd-contaminated soil was therefore not recommended in view of the increasing influx of Cd into food chain especially on flooded soils.  相似文献   

14.
北方泥炭地甲烷排放研究: 综述   总被引：7，自引：0，他引：7  
D. Y. F. LAI 《土壤圈》2009,19(4):409-421
Northern peatlands store a large amount of carbon and play a significant role in the global carbon cycle. Owing to the presence of waterlogged and anaerobic conditions, peatlands are typically a source of methane (CH4), a very potent greenhouse gas. This paper reviews the key mechanisms of peatland CH4 production, consumption and transport and the major environmental and biotic controls on peatland CH4 emissions. The advantages and disadvantages of micrometeorological and chamber methods in measuring CH4 fluxes from northern peatlands are also discussed. The magnitude of CH4 flux varies considerably among peatland types (bogs and fens) and microtopographic locations (hummocks and hollows). Some anthropogenic activities including forestry, peat harvesting and industrial emission of sulphur dioxide can cause a reduction in CH4 release from northern peatlands. Further research should be conducted to investigate the in fluence of plant growth forms on CH4 flux from northern peatlands, determine the water table threshold at which plant production in peatlands enhances CH4 release, and quantify peatland CH4 exchange at plant community level with a higher temporal resolution using automatic chambers.  相似文献   

15.
The phosphate adsorption and surface charge characteristics of the tropical and subtropical soils derived from different parent materials in China were determined, and their relations to soil mineralogy were analysed. The results showed that all soil phosphate adsorption curves were well fitted by Freundlich equation and Langmuir equation. The maximum buffering capacity of P ranged from 66 to 9 880 mg kg-1, with an increasing order of purple soil, skeletal soil, red soil, lateritic red soil, yellow soil and latosol; and the highest value was 149 times the lowest value, which indicated great differences among these soils in phosphate adsorption and supplying characteristics. The pH0 (zero point of charge) values obtained by salt titration-potential titration varied from 3.03 to 5.49, and the highest value was found in the latosol derived from basalt whereas the lowest value was found in the purple soil. The correlation analysis indicated that the main minerals responsible for phosphate adsorption in the soils were gibbsite, amorphous iron oxide and kaolinite; and the pH0 was mainly controlled by kaolinite, gibbsite and oxides.  相似文献   

16.
我国东南部地区红壤表土养分的淋溶及再分布   总被引：6，自引：0，他引：6  
The leaching and redistribution of nutrients in the surface layer of 4 types of red soils in Southeast China were studied with a lysimeter experiment under field conditions. Results showed that the leaching concentrated in the rainy season (from April to June). Generally, the leaching of soil nutrients from the surface layer of red soils was in the order of Ca > Mg > K > NO3-N. In fertilization treatment, the total amount of soil nutrients leached out of the surface layer in a red soil derived from granite was the highest in all soils. The uptake by grass decreased the leaching of fertilizer ions in surface layer, particularly for NO3-N. Soil total N and exchangeable K, Ca and Mg in the surface layer decreased with leaching and grass uptake during the 2 years without new fertilization of urea, Ca(H2PO4)2, KCl, CaCO3 and MgCO3. Ca moved from the application layer (0~5 cm) of fertilizer and accumulated in the 10~30 cm depth in the soils studied except that derived from Quaternary red clay. The deficiency of soil exchangeable K will become a serious degradation process facing the Southeast China.  相似文献   

17.
Application of lime or gypsum is a common agricultural practice to ameliorate soils with low pH which prohibits crop production. Its integrated effect on soil properties in a red soil derived from Quaternary red clay in Southeast China is discussed in this paper. Application of gypsum in the topsoil without leaching raised soil pH and promoted the production of soil NH4, but lime addition had a contrary effect. Generally, application of lime and/or gypsum has little effect on soil electrical properties. Gypsum had a little effect on soil exchange complex and its effect went down to 30 cm in depth. The effect of lime reached only to 5 cm below its application layer. With leaching, Ca transferred from top soil to subsoil and decreased exchangeable Al in subsoil. Gypsum application led to a sharp decrease in soil exchangeable Mg but had no effect on K.  相似文献   

18.
Paddy fields in the southeastern basin of Dianchi Lake have rapidly changed to greenhouses since 1999. A total of 61 surface soil samples, including 43 greenhouse soils, 12 upland soils, and 6 paddy soils, were collected from a flat lowland area mainly used for agricultural production fields in the southeastern basin of Dianchi Lake. Analyses of the soil samples indicated that the greenhouse soils were characterized by a lower organic matter content, lower pH, and higher soluble nutrients than the paddy soils in the area. The lower organic matter content of the greenhouse soils was ascribed to environmental or management factors rather than the clay content of the soil. Accumulation of soluble nutrients, especially inorganic N, was due to over-application of fertilizers, which also caused soil acidification. The average amount of readily available N, P, and K accumulated in the greenhouse soils was estimated to be equal to or higher than the annual input of these nutrients as a fertilizer, indicating that a reduction in fertilizer application was possible and recommended. In contrast, a very low available Si content was observed in the paddy soils, suggesting the need for Si application for rice production.  相似文献   

19.
三叶草对污染土壤中芘的去除研究   总被引：1，自引：0，他引：1  
Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons (PAHs), ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes, in the last decade. In this study, a pot experiment was conducted to investigate the potential of phytoremediation of pyrene from spiked soils planted with white clover (Trifolium repens) in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1. The results showed that growth of white clover on pyrenecontaminated soils was not affected. The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils. At the end of the experiment (60 d), the average removal ratio of pyrene in the spiked soils with white clover was 77%, which was 31% and 57% higher than those of the controls with or without micobes, respectively. Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration. However, the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation. Bioconcentration factors of pyrene (BCFs, ratio of pyrene, on a dry weight basis, in the plant to that in the soil) tended to decrease with increase in the residual soil pyrene concentration. Therefore, removal of pyrene in the contaminated soils was feasible using white clove.  相似文献   

20.
The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution.Montmorillonite was found in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit,and some lateritic red soil,red soil and yellow soil with a low weathering degree.Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit.1.4nm intergradient mineral appeared frequently in yellow soil,red soil and lateritic red soil.The content of 1.4nm intergradient mineral increased with the decrease of weathering degree from lateritic red soil to red soil to yellow soil.Hydrous micas were more in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit.and puple soil from purple shale than in other soils.Kaolinte was the most important clay mineral in the soils iun this province.The higher the soil weathering degree,the more the kaolinite existed.From yellow soil to red soil to lateritic red soil,kaolinite increased gradually,Kaolinite was the predominant clay mineral accompanied by few other minerals in typical lateritic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities.The soil derived from the paent rocks rich in feldspar contained more tubular halloysite.Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt gibbsite in the soils in this district was largely“primary gibbsite” which formed in the early weathering stage.Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to lateritic red soil.Goethite also decreased in the same sequence while hematite increased.  相似文献   

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