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1.
大多数土壤的有机磷(Po)占全磷30% ~ 65%,矿化后可被植物直接利用,成为生态系统生物有效磷重要来源。准确测定Po形态组成及矿化速率是科学利用土壤Po库的基础。本文目的是对目前常见土壤Po形态组成和矿化速率测定技术的优缺点、适用范围进行总结分析,为研究人员选择合适测定技术提供依据。搜集并分析近20年来中国知网和Web of Science数据库中92篇关于Po形态组成与矿化速率方法研究论文。介绍了3种常用Po形态测定技术(连续分级法、酶水解法和核磁共振法)和近年来兴起的3种Po矿化速率测定技术(同位素稀释技术、连续观测-差减法和模型法)的基本原理,分析了几种技术适用范围、主要优缺点和互补性。尽管目前仍无针对土壤Po形态组成和矿化速率“最佳”测定方法,但是,研究人员可根据待测土壤理化性质和实验目的选择“合适”的测定技术。提出未来应在酶水解技术标准化、13C和31P核磁共振技术联用、发展包含植物因素Po矿化速率测定技术、联用形态和矿化速率测定技术等方面开展深入研究。 相似文献
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土壤磷形态组分分级及31P-NMR 技术应用研究进展 总被引:4,自引:1,他引:3
农田生态系统中土壤磷形态转化,影响土壤磷对作物的有效供应。土壤磷分为无机磷和有机磷两大部分。化学连续提取法 (chemical sequential fractionation,CSF) 研究土壤磷形态分级,采用不同的化学提取剂,分级提取土壤中组成或分解能力接近的有机无机含磷化合物,是目前表征土壤磷素形态的重要方法。但该方法虽历经改进,仍难以确切反映土壤磷的实际组成,提取的不同磷形态间存在重叠,有机磷和无机磷组分分级存在一定的误差;不同分级磷组分对作物的有效性,需谨慎评估。核磁共振波谱技术 (nuclear magnetic resonance,NMR) 根据核磁共振波谱图上共振峰的位置、强度和精细结构来研究土壤中含磷化合物的分子结构。液相31P-NMR 可以同吋检测出土壤中多种磷组分,如正磷酸盐、磷酸单酯、磷酸二酯、膦酸脂、焦磷酸盐和多聚磷酸盐,识别土壤提取物磷形态,可将有机磷与无机磷分开。本文综述了应用31P-NMR 技术研究土壤磷形态组分的一些进展,总结了样品制备过程、NMR 测试参数及在土壤磷形态转化研究中的应用。二维31P-NMR 技术发展为鉴定分析土壤中更多种类的含磷化合物提供了契机。 相似文献
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不同温室蔬菜种植模式下土壤磷素形态分布与转化 总被引:3,自引:0,他引:3
采用蒋柏藩-顾益初无机磷分级浸提法,研究了15a长期有机、综合和常规种植3种温室蔬菜生产体系下石灰性土壤磷形态分布及转化特征。结果表明:种植模式及施肥年限对土壤有机磷含量和各形态无机磷含量均有显著影响,且交互作用显著。随着施肥时间延长,3种种植模式土壤有机磷含量与无机磷形态Ca2-P、Ca8-P、Fe-P含量不断升高,Al-P、O-P、Ca10-P含量呈现不规则变动,差异较小;有机模式土壤有机磷含量与无机磷形态Ca2-P、Ca8-P、Fe-P含量均高于常规和综合模式,O-P、Ca10-P含量略小于常规和综合模式。在各磷素占比中,中等活性磷源(Ca8-P、Fe-P、Al-P)>潜在磷源(O-P、Ca10-P)>有效磷源(Ca2-P)。表层土中有机磷占全磷的8%~23%,亚表层土中有机磷占全磷的6%~13%。有机模式促进了无机磷各形态之间、有机磷和无机磷形态之间的转化过程,0~20 cm土层的磷素转化比2... 相似文献
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长期施肥褐土不同磷组分对磷素盈余的响应 总被引:2,自引:1,他引:2
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在利用土壤侵蚀模型估算侵蚀速率的过程中,背景值点选取的好坏直接关系到结论是否可靠,如果能通过科学计算得出研究区域背景值,将大大提高背景值的准确性,对研究土壤侵蚀具有重大意义。土壤未受到侵蚀和沉积的背景区,首先假设全球大气沉降量为定值,研究把210Pbex沉降过程以一年为时间尺度划分为n年,经过n年以后(n=0,1,2,…,∞),土壤中210Pbex沉降量和经过衰变减少量达到平衡,土壤中210Pbex含量趋于稳定。假设各地年平均降水量为定值,通过研究发现210Pbex的大气沉降通量与年降水量之间存在极显著相关(P < 0.01),区域年降水量是影响土壤中210Pbex量的主要因素,由于年平均降水量不同,全球各地土壤中210Pbex含量都会达到不同的稳定值,从而建立土壤中210Pbex含量与年降水量关系模型。研究210Pbex来源、沉降的连续性和稳定性,提出利用区域年平均降水量来计算该地区的210Pbex背景值,建立土壤中210Pbex背景值含量动态平衡模型,为准确确定210Pbex背景值提供了方法,对研究土壤侵蚀具有重要的意义。 相似文献
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珠江三角洲平原土壤磷剖面分布及形态特征研究 总被引:4,自引:3,他引:1
《土壤通报》2015,(5):1025-1033
以珠江三角洲平原由三角洲沉积物、河流沉积物和滨海沉积物发育形成的水耕人为土(水稻土)为对象,研究了水田、果园、菜地3种利用方式下不同发生层土壤全磷(TP)、有机磷(Po)、有效磷(AP)、无机磷(Pi)组分的含量和剖面分布特征,并利用液相31P核磁共振(NMR)技术测定了耕层土壤中磷形态分布。结果表明,珠江三角洲平原农田土壤全磷、有机磷、有效磷和各形态无机磷含量随土层深度增加呈减小的趋势,耕层土壤中全磷、有效磷、Al-P和Fe-P明显富集;菜地和果园耕层土壤中全磷、有效磷、Al-P、Fe-P、Ca-P和O-P含量均高于水田。土壤磷素以无机磷形态为主,无机磷、有机磷占全磷比例平均值分别为71.3%和28.7%。土壤无机磷组分以O-P和Fe-P为主,Al-P最低。Al-P、Fe-P、Ca-P、O-P与全磷呈极显著或显著正相关,有效磷与Al-P、Fe-P、O-P、全磷呈极显著正相关;Fe-P和Al-P是土壤有效磷的主要贡献者。31P-NMR结果表明,耕层土壤磷形态均以正磷酸盐为主;土地利用方式影响土壤磷组分,菜地耕层土壤中磷形态包括正磷酸盐、磷酸单酯和焦磷酸盐,水田和果园包括正磷酸盐、磷酸单酯、磷酸二酯和焦磷酸盐;水田土壤中正磷酸盐所占比例最低,磷酸单酯和磷酸二酯所占比例最高;成土母质对水田耕层土壤各形态磷所占比例影响很小。 相似文献
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磷肥减施对玉米根系生长及根际土壤磷组分的影响 总被引:5,自引:1,他引:4
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磷是农作物生长发育的必需元素,为了保证我国粮食安全,提高农作物的产量,提高磷肥有效性十分重要。本试验选取三种石灰性土壤(郑州潮土、周口褐土和昌图风沙土)为研究对象,通过90天的室内埋土试验,在三种土壤中研究氨基酸与磷酸一铵配施对提高土壤中磷肥有效性的影响。研究结果表明:(1)氨基酸在三种石灰性土壤中均能够提高磷酸一铵的有效性,郑州潮土、周口褐土和昌图风沙土的磷肥有效性与单施磷酸一铵相比分别提高了21.16%、10.87%和4.06%;(2)氨基酸的加入降低了土壤中Ca2-P向Ca8-P或其他难溶形态磷的转化,通过对三种土壤进行相关性和通径分析的得出在郑州潮土、周口褐土和昌图风沙土中主要决策因子是Ca2-P,决策系数分别到达了0.836、0.946和0.712(P < 0.05),郑州潮土、周口褐土主要限制因子是Ca8-P,决策系数分别为?0.066、?0.401(P < 0.05),昌图风沙土主要限制因子是Ca8-P和Fe-P,决策系数分别为?0.080和?0.105(P < 0.05);(3)氨基酸的加入能够降低三种石灰性土壤的pH和CaCO3含量,有利于提高磷肥有效性;(4)通过对三种土壤的有效磷含量与土壤理化性质进行冗余分析,得出有机质(SOM)和碳酸钙 (CaCO3)是影响磷肥在三种土壤中固定速率差异的主要原因,SOM和CaCO3分别解释了有效磷含量全部变异的36.5%和25.6% (P < 0.05)。氨基酸在三种石灰性土壤中均能够提高磷肥有效性,主要途径是降低土壤的pH和CaCO3含量,抑制Ca2-P的快速转化。在三种石灰性土壤中,氨基酸作用有差异的主要原因是三种土壤中SOM和CaCO3含量的差异,提高SOM,降低土壤中CaCO3能够降低土壤对磷的固定,提高磷肥有效性。 相似文献
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氮锌配施对冬小麦根土界面锌有效性及形态分级的影响 总被引:3,自引:1,他引:2
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【目的】研究三江源区高寒草甸牧草对不同形态氮素的吸收利用和残留氮素在土壤中的去向及分配,以期为制定三江源区高寒草甸草场养分科学添加方案提供理论依据。【方法】于2020年6月至2021年9月,在青海省称多县高寒草甸试验站开展15N田间微区示踪试验,试验设置3个不同氮素形态处理,分别为(15NH4)2SO4、Ca(15NO3)2、CO(15NH2)2,各处理的氮素施用量均为N 300 kg/hm2。分析了施肥当年和次年不同形态氮素在高寒草甸牧草地上部、地下部中的含量,及在0—15、15—30 cm土层土壤中的去向及分配。【结果】1)在施肥当年,与Ca(15NO3)2、(15NH4)2SO4<... 相似文献
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A study of soil and fertilizer phosphorus intake by Barley plants,using Radioactive tracer technique
Introduction Phosphorus applied on a phosphate deficient soil, by increasing the root development of the plant, or by stimulating the soil microflora especially in the rhizosphere, may increase the amount of phosphorus which the plant takes up from the soil. This present paper is a report on a pot culture investigation of such an effect of added phosphorus. 相似文献
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Human activity has increased the amount of N entering terrestrial ecosystems from atmospheric NO3− deposition. High levels of inorganic N are known to suppress the expression of phenol oxidase, an important lignin-degrading enzyme produced by white-rot fungi. We hypothesized that chronic NO3− additions would decrease the flow of C through the heterotrophic soil food web by inhibiting phenol oxidase and the depolymerization of lignocellulose. This would likely reduce the availability of C from lignocellulose for metabolism by the microbial community. We tested this hypothesis in a mature northern hardwood forest in northern Michigan, which has received experimental atmospheric N deposition (30 kg NO3−-N ha−1 y−1) for nine years. In a laboratory study, we amended soils with 13C-labeled vanillin, a monophenolic product of lignin depolymerization, and 13C-labeled cellobiose, a disaccharide product of cellulose degradation. We then traced the flow of 13C through the microbial community and into soil organic carbon (SOC), dissolved organic carbon (DOC), and microbial respiration. We simultaneously measured the activity of enzymes responsible for lignin (phenol oxidase and peroxidase) and cellobiose (β-glucosidase) degradation. Nitrogen deposition reduced phenol oxidase activity by 83% and peroxidase activity by 74% when compared to control soils. In addition, soil C increased by 76%, whereas microbial biomass decreased by 68% in NO3− amended soils. 13C cellobiose in bacterial or fungal PLFAs was unaffected by NO3− deposition; however, the incorporation of 13C vanillin in fungal PLFAs extracted from NO3− amended soil was 82% higher than in the control treatment. The recovery of 13C vanillin and 13C cellobiose in SOC, DOC, microbial biomass, and respiration was not different between control and NO3− amended treatments. Chronic NO3− deposition has stemmed the flow of C through the heterotrophic soil food web by inhibiting the activity of ligninolytic enzymes, but it increased the assimilation of vanillin into fungal PLFAs. 相似文献
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The use of environmental radionuclides as tracers in soil erosion and sedimentation investigations: recent advances and future developments 总被引:9,自引:0,他引:9
Although much of the recent attention on the environmental problems has focused on climatic change, there is also increasing concern that accelerated soil erosion and associated land degradation represent a major problem for sustainable development and environmental protection. There is an urgent need to obtain reliable quantitative data on the extent and rates of soil erosion worldwide to provide a more comprehensive assessment of the magnitude of the problems and to underpin the selection of effective soil conservation measures. The use of environmental radionuclides, in particular 137Cs, affords an effective and valuable means for studying erosion and deposition within the landscape. The key advantage of this approach is that it can provide retrospective information on medium-term (30–40 years) erosion/deposition rates and spatial patterns of soil redistribution, without the need for long-term monitoring programmes. Advantages and limitations of the technique are highlighted. The launching of two closely linked International Atomic Energy Agency (IAEA) research networked projects in 1996 involving some 25 research groups worldwide has made a major contribution to co-ordinating efforts to refine and to standardise the 137Cs technique. The efficacy and value of the approach has been demonstrated by investigations in a number of environments. Significant developments that have been made to exploit its application in a wide range of studies are reported in this review paper. Other environmental radionuclides, such as unsupported 210Pb and 7Be offer considerable potential for use in soil erosion investigations, both individually and complementary to 137Cs. The IAEA through research networks and other mechanisms is promoting further development and applications of these radionuclides in soil erosion and sedimentation studies for a sustainable resource use and environmental protection. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(1-2):265-271
This trial was carried out to study the evolution of the nutrient parameters of the nutrient solution applied to tomato plants (Lycopersicum sculentum Mill. Forteza) cultivated in Mediterranean greenhouse conditions under different fertigation management models. The dynamic model is based on soil water content, which was measured by tensiometers, and on soil solutions obtained with suction cups (porous ceramic cup water samplers). The local traditional method consists of following technical recommendations, and the classical model requires the estimation of Crop Factor (Kc) and knowing the nutrient extraction. Nutrient solution and water applied are functions of the fertigation management criteria. The water used for fertigation was classified as C4-S3 according to the Riverside classification system. The cultivation period lasted from 15 August to 20 April. The nutrient parameters studied in nutrient and soil solution were pH, electrical conductivity (EC), nitrate (NO3 ?), phosphate (H2PO4 ?), potassium (K+), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and chloride (Cl?). The pH shows similar trends under the different treatments. Electrical conductivity is in the range of 2.8–4.5 dS m?1. Chloride, sodium, magnesium, and sulfate are exclusively modified by the salt concentration in the irrigation water, so it can be assumed that the three treatments vary equally. Nitrate, potassium, phosphate, and calcium are modified depending on each fertigation management method. Soil solution is modified by the nutrient solution applied. Dynamic management allows low nutrient concentration in the nutrient solution to be maintained and keeps soil nutrient concentration low, reducing fertilizer losses and therefore aquifer contamination. 相似文献
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As part of a research program on the transfer withinfreshwater ecosystems of the radionuclides present inthe weakly radioactive liquid effluents from nuclearpower stations, this article presents an assessment ofthe dynamics of zooplankton contamination from water.The experiments were carried out on young pre-adultdaphnids, placed at a density of 250 individualsL-1, in 0.45 m filtered river water. Inorder to maintain the radionuclide contamination at ahigh level and to limit alterations in the chemicalcharacteristics of the medium, the water was reneweddaily. The dynamics of contamination were described bya one (137Cs) or a two compartmental model(110mAg, 60Co and 54Mn), taking intoaccount the fluctuations of the radionuclideconcentration in the water, as well as the growth rateof the daphnids. The contamination levels weredescribed by the steady state value of theconcentration factor, which was 2870 mL g-1 wetweight, 320 mL g-1 wet weight, 265 mL g-1wet weight and 30 mL g-1 wet weight, for110mAg, 54Mn, 60Co and 137Cs,respectively. During the depuration phase,radioactivity decrease in daphnids was a very fastphenomenon indicating that radionuclide adsorption tothe surface was the major process involved in thecontamination of daphnids. The two correspondinghalf-lives of the depuration kinetics were 10 min and7 d, 20 min and 1 d and 3 hr and 1.5 d for60Co, 110mAg and 54Mn, respectively.The loss of 137Cs was characterised by a singlehalf-life of 0.3 d. 相似文献
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Hiromi Nakanishi Houdo Tanaka Kouki Takeda Keitaro Tanoi Atsushi Hirose Seiji Nagasaka 《Soil Science and Plant Nutrition》2013,59(6):801-808
AbstractRadioactivity levels of cesium (Cs)-134 and 137Cs in bamboo [Phyllostachys reticulata (Rupr) K. Koch] sprouts grown from April to June 2011 over a wide area (including Fukushima Prefecture) were elevated (max. 3100 Bq kg?1 fresh weight) after the Tokyo Electric Power Company, Inc. (TEPCO) Fukushima Daiichi Nuclear Power Plant disaster in March 2011. Bamboo sprouts in 2012 also contained high radioactivity levels. Radioactivity imaging analysis of bamboo sprouts harvested in 2012 showed increasing concentration gradients of radioactivity from the lower parts to the top of the sprouts. The peels were individually separated from the sprouts, and the inner edible part (trunk) was cross-sectioned at the internodal sections from the top to the lower parts. Each segmented trunk and its corresponding peel were analyzed for radioactive cesium (134Cs and 137Cs) and stable cesium (133Cs). The concentrations of 134Cs and 137Cs showed significant increases from the lower part to the top, whereas 133Cs showed an almost constant value in the trunk and peel except in the peel of the top node. We speculated that 134Cs and 137Cs in newly emerging bamboo sprouts in 2012 were translocated mainly from various plant tissues (where the fallout was layered on the bamboo tissues) in older bamboo, while 133Cs was translocated from the soil through the roots of the new bamboo sprouts and was present in the roots and stems. 相似文献
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Skwarzec Bogdan Boryło Alicja Strumińska Dagmara I. 《Water, air, and soil pollution》2004,159(1):165-173
The aim of the work was to determine the concentration of 234U and 238U and calculate the values of the 234U/238U activity ratio in samples of living organisms, bottom water, surface and interstitial water and also sediments from the various regions of southern Baltic Sea. The knowledge of 234U/238U activity ratio in ecosystem allows getting know about the mechanisms and processes of uranium transport and origin.The activities of the analyzed uranium radionuclides in samples were measured using alpha spectrometry. The results of researches revealed diversified concentrations of uranium in the sediments of the southern Baltic Sea (sea and coastal waters) and increase of uranium with sediment depth, suggesting the diffusion of uranium from sediments to water through interstitial water and diagenesis processes in sediment material. The nuclides of uranium 234U and 238U were radioactive state equilibrium in most of the sediments. The values of the 234U/238U activity ratio oscillate around one. In bottom, surface, interstitial water and living organisms mean values of the 234U/238U activity ratio are between 1.12 and 1.15. Higher uranium concentration was observed in samples of sediments and seawater after flood in 1997 and torrential rainfalls in 2000–2001. River waters are characterized by higher 234U/238U activity ratio. The values of the 234U/238U activity ratio equal 1.27 in sediments and 1.34–1.38 in seawater indicate the influence of fresh waters. 相似文献
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Direct plant uptake of organic nitrogen (N) is often studied using the dual-labeling approach (15N + 13C or 15N + 14C). However, the method might be hampered by uptake of labeled inorganic carbon (C) produced by mineralization of labeled organic compounds. Here we report the results from a triple labeling experiment (15N + 13C + 14C) investigating whether root uptake of labeled inorganic C can bias the results obtained in studies of organic N uptake using dual-labeled amino acids (15N, 13C). In a rhizosphere tube experiment we investigated 13C and 14C uptake by maize either supplied with labeled glycine or , but found no differences in uptake rates between these C-sources. The uptake of inorganic C to the shoot tissue was higher for maize grown in full light compared to shading, which indicates a passive uptake of inorganic C with water. We conclude that uptake of inorganic C produced by mineralization of amino acids can significantly bias the interpretations of organic N uptake studies using dual-labeling. 相似文献