SO42-和Cl-对稻田土壤养分及其吸附解吸特性的影响

利用长期定位试验 ,比较了长期施用含SO₄^2-和Cl^- 化肥 22年后稻田土壤的 pH值、养分状况及其吸附解吸特性。结果表明 ,长期施用含SO₄^2-化肥 ,土壤有机质、速效氮和速效钾的含量较高 ,但全量氮磷钾的含量较低 ;长期施用含Cl^- 化肥 ,土壤全量氮磷钾和速效磷的含量较高 ,但pH值相对较低。长期施用含上述二种阴离子的化肥后 ,土壤对H₂PO₄^-的最大吸附量均较大 ,且在Cl^- 处理下土壤对H₂PO₄^-吸附的结合能较大 ,而SO₄^2-处理下土壤在同等吸附量时对H₂PO₄^-的解吸量相应较多。长期施用含SO₄^2-的化肥亦使土壤对钾素的供应强度较大 (ΔK0的绝对值较大 )、缓冲能力增强 (AR0值较高 ) ,而长期施用含Cl^- 的化肥时则与SO₄^2-相反     

空间电场对植物吸收CO2和生长速度的影响

为研究空间电场对植物吸收CO₂和生长速度的影响，首先采用同位素示踪法，分析了不同空间电场调控营养液栽培的番茄秧吸收CO₂气体和HCO^-₃阴离子的能力，证实了 ¹⁴C—HCO^-₃是一种受控于空间电场变化的阴离子，且空间电场强度的变化方向调控着 ¹⁴C—HCO^-₃阴离子流的流动方向。在此基础上以蕹菜(空心菜)为试验材料，采取空间电场与增施CO₂浓度的参数组合，做对比生长试验，通过红外线CO₂分析法揭示了空间电场的极性对植物吸收CO₂的速度有显著影响，且正向空间电场能显著促进植物对CO₂的吸收，并得到正向空间电场与足量的CO₂浓度相配合能大幅度提高温室蔬菜生长速度，使作物产量倍增的结论，为建立空间电场促进植物生长技术提供理论依据。     

淡水湿地不同围垦土壤非耕季节呼吸速率差异

选择何种湿地利用方式,使得土壤固碳能力及CO₂气体排放受到的影响最小,是合理利用湿地、减少温室气体排放的关键所在,湿地土壤呼吸不仅受环境条件的影响,还受土壤本身性状的影响。以皖江地区为研究区域,利用定位试验对天然湿地及不同围垦利用方式下土壤在非耕季节CO₂排放通量、大气温度及表层土壤温度进行测定,并对其土壤TOC含量进行分析。结果表明,CO₂排放通量:水稻田[700.70 mg/(m²·h)]> 旱地[433.80 mg/(m²·h)]> 天然湿地[302.66 mg/(m²·h)],天然湿地土壤TOC含量明显高于围垦旱地及水稻田(0-30 cm),说明天然湿地较围垦旱地和水稻田对大气中CO₂浓度贡献最小,能存储更多的碳。探讨了CO₂排放通量与温度的相关性,得出3种土壤类型CO₂排放通量与大气温度和表层土壤温度均呈正相关关系。     

设施菜田土壤呼吸速率日变化特征分析

研究设施菜田土壤呼吸速率日变化特征对于了解CO₂排放对环境和作物生长的影响十分重要。本研究采用CO2红外分析仪 动态箱法在2009年秋冬季和2010年冬春季监测了不同有机肥和氮肥处理下设施菜田土壤呼吸速率的日变化特征。结果表明: 施用有机肥和秸秆明显提高设施菜田土壤呼吸速率, 尤其是在高氮投入下, 鸡粪和小麦秸秆混施土壤呼吸速率明显高于其他处理; 不同季节各处理土壤呼吸速率的日变化特征基本一致, 土壤呼吸速率的最大值出现在14:00-17:00; 随着温度升高, 土壤呼吸速率逐渐增加, 但是过高的温度和CO₂浓度均会抑制土壤呼吸速率; 上午8:00-11:00测定的土壤呼吸速率值与土壤呼吸速率日平均值基本一致, 可采用上午8:00-11:00土壤呼吸速率的观测值评估设施菜田CO₂的排放量; 施肥、温度和温室内近地面CO₂浓度是影响不同季节土壤呼吸速率日变化的主要因素, 合理调控对于实现设施蔬菜的可持续发展具有重要意义。     

黄土丘陵区典型沟道侵蚀诱发的CO2通量估算

以黄土丘陵区典型侵蚀沟道为对象,基于沟道剖面有机碳和¹³⁷Cs数据,采用碳库重分布模型估算了典型沟道侵蚀诱发的CO₂通量,并通过检验模型预测效率、解析影响因子,提出了模型校正的思路。结果表明:(1)在长期侵蚀作用下,沟道侵蚀区和沉积区均表现为剧烈的侵蚀效应,侵蚀区侵蚀速率介于30.99~46.44 mm/a,沉积区侵蚀速率介于34.20~37.88 mm/a,沉积区土壤流失速率略小于侵蚀区;(2)碳库重分布模型估算显示,侵蚀区与沉积区均表现为较强烈的碳源效应,侵蚀区CO₂通量介于18.41~28.44 g/(m²·a),沉积区CO₂通量介于22.19~29.25 g/(m²·a);(3)侵蚀部位、土壤容重、有机碳含量、侵蚀量、沟道平均坡度、植被地上部与地下部生物量共同解释了碳库重分布模型预测效率的变异特征(R²=0.68),其中侵蚀部位、侵蚀量、有机碳含量、土壤容重、植被地下部对预测效率有强驱动效应;(4)引入被忽略的植被新输入有机碳库参数,有望校正碳库重分布模型,提升模型预测效率。该研究结果明确了碳库重分布模型在沟道侵蚀区相比沉积区有更高的CO₂通量预测效率,为进一步提高模型的预测精度,可以考虑引入植被输入有机碳库作为校正参数。     

用13C脉冲标记方法研究施肥与地膜覆盖对玉米光合碳分配的影响

基于沈阳农业大学棕壤长期定位试验站不同施肥与地膜覆盖处理,采用原位¹³CO₂脉冲标记的方法示踪了¹³C在玉米-土壤系统中的转移与分配,探讨了施肥与地膜覆盖对玉米光合碳动态变化的影响。结果表明：玉米-土壤系统光合固定碳转移较快,且分配差异较大,其δ¹³C值在标记1 d表现为茎叶>根>根际土壤>土体,且同一施肥处理下传统栽培高于覆膜栽培。标记15 d玉米植株和根际土壤δ¹³C值降低,而土体δ¹³C值却略有升高。传统栽培不施肥处理对¹³C富集程度最大,其中茎叶和根δ¹³C值在标记1 d分别为1 568‰和598‰;标记15 d为178‰和147‰。玉米-土壤系统¹³C固定比例在标记1 d和15 d分别为64.01%和38.65%,且¹³C分配按茎叶、根、根际土壤、土体顺序依次降低。覆膜施有机肥处理显著提高了光合固定¹³C数量及¹³C在玉米和土壤中的分配比例,是促进¹³C同化与分配的主要方式。     

煤粉尘添加量与温度对山西省两种土壤碳释放规律的影响

采用室内培养试验, 观测不同温度和不同煤粉尘用量条件下山西省电厂土和焦化厂土两种土壤的碳释放规律。结果表明, 室温(16~23 ℃)和25 ℃恒温下, 培养前期(4~9 d)土壤CO₂ 的释放量均为最大, 且25 ℃ 恒温培养土壤CO₂ 的释放量是室温条件下的2 倍左右。随煤粉尘添加量的增加, 土壤CO₂ 的释放量显著增加,且土壤活性有机质相应增加, 添加高量煤粉尘土壤CO₂ 的释放量最高达57.5 mg·kg^-1·d^-1, 两种土壤活性有机碳的增幅为0.3~3.8 g·kg^-1。不同温度和不同煤粉尘用量条件下电厂土释放的CO₂ 均高于焦化厂土, 可能是电厂土含有较高的有机碳和较低的黏粒所致。由此可知, 温度是影响土壤有机碳分解的主要因素, 其次是添加煤粉尘的量, 土壤理化性质也是原因之一。本研究表明, 煤粉尘的降落一方面增加了土壤CO₂ 的释放, 另一方面增加了土壤碳库。     

坡面片蚀泥沙有机碳组分及13C同位素不均匀富集对水动力学参数的响应

[目的] 探究片蚀泥沙轻组有机碳(LF_OC)和重组有机碳(HF_OC)不均匀富集的水动力学和碳同位素特征,为正确理解水蚀作用下土壤有机碳库变化提供理论与技术支撑。[方法] 以陕西省咸阳市杨凌区土为研究对象,采用改进"三区"移动式变坡钢制土槽,结合人工模拟降雨技术,测定径流水动力学参数和泥沙各粒径团聚体有机碳组成及其δ¹³C值,并辅以棕壤侵蚀泥沙有机碳δ¹³C值和水力参数,验证土试验结果的准确性。[结果] ①雨强和坡度较小时,侵蚀泥沙LF_OC和HF_OC易发生富集,且相较黏粉粒和微团聚体,大团聚体LF_OC与HF_OC含量受雨强和坡度的影响更大; ②侵蚀泥沙黏粉粒中有机碳δ¹³C值与其有机碳活跃分数(λ)呈负相关,而其他粒径团聚体有机碳δ¹³C值与其λ呈显著正相关(p<0.05); ③流速与黏粉粒λ显著正相关(p<0.05),雷诺数与各粒径团聚体有机碳δ¹³C值均呈显著负相关(p<0.01),片蚀过程中流速越大,黏粉粒中LF_OC越易于优先输移,而紊流加剧则促进低δ¹³C值团聚体有机碳的优先输移; ④对于侵蚀泥沙黏粉粒,流速和雷诺数越大,其有机碳δ¹³C值越小,λ越大;对于微团聚体和大团聚体,雷诺数越小,其有机碳δ¹³C值与λ越大。[结论] 片蚀过程中轻重组有机碳流失与流速和雷诺数密切相关。并进一步验证了¹³C同位素对侵蚀泥沙有机碳示踪的有效性。     

不同施肥条件下农田硝态氮迁移的试验研究

NO^-₃-N的淋失是旱地农田氮素损失的重要途径之一，也是引起地下水污染的一个主要原因。在黄土高原地区，夏玉米生长正逢雨季，是NO^-₃-N淋失的主要时期。该研究基于阻水层理论和黄土高原地区传统的垄作习惯，在手工模拟机具成垄压实施肥的基础上研究了该施肥法与传统的平地施肥、垄沟施肥(成垄不压实)条件下土壤NO^-₃-N的迁移动态，结果表明，在供水量相同条件下，由于平地和垄沟条件下水分分布的差异，导致平地土壤中的NO^-₃-N较垄沟耕作易于迁移。在生育前期，由于作物根系对NO^-₃-N的吸收和拦截，成垄压实与成垄不压实施肥对阻止NO^-₃-N随水下移差异不大；生育后期，当作物需肥量减小时，成垄压实施肥能够阻止NO^-₃-N向深层土壤迁移累积。玉米收获后，3种施肥方式下土壤NO^-₃-N迁移深度为平地(>60 cm)>垄沟施肥(>45 cm)>成垄压实施肥(＜35 cm)。     

NO-3胁迫下K+、Ca2+对黄瓜幼苗膜质过氧化及活性氧清除酶系统的影响

通过水培试验探讨了NO^-₃胁迫下K⁺、Ca²⁺对黄瓜幼苗膜质过氧化及活性氧清除酶系统的影响。结果表明，在相同NO^-₃浓度胁迫7d后， Ca²⁺浓度越大，膜脂过氧化产物丙二醛(MDA)含量越高，而K⁺浓度越大，电解质相对渗透率越高，由此说明K⁺、Ca²⁺对细胞膜造成伤害的机理不同。黄瓜幼苗活性氧清除酶系统对K⁺、Ca²⁺的响应亦不同，在一定程度上，K⁺和Ca²⁺ 可提高SOD、POD和CAT活性，保护植物免受自由基伤害，继而可增强植物对逆境的适应能力。     

Nutrient Solution and Nutrient Soil Solution Parameter Evolution in Tomato with Dynamic Fertigation under Saline Conditions

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.     

应用15N稀释法测定土壤氮素初级转化速率的一些关键技术

本文综合评述了应用~(15)N库稀释法测定土壤氮素初级转化速率的一些关键技术,即~(15)N标记土壤氮库的方法、~(15)N的加入量、丰度和标记物种类的选择,以及初始取样时间的确定。只有合理地运用这些关键技术,才能更准确地测定土壤氮素初级转化速率,进而更真实地表征土壤氮素的实际周转状况。     

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.     

Radioactive cesium distribution in bamboo [Phyllostachys reticulata (Rupr) K. Koch] shoots after the TEPCO Fukushima Daiichi Nuclear Power Plant disaster

Abstract

Radioactivity 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.     

Activity Disequilibrium between 234U and 238U Isotopes in Southern Baltic

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.     

Die Aufnahme von137Cs und 90Sr durch verschiedene sommerrapsgenotypen aus dem Boden*

Die Aufnahme von ¹³⁷Cs und ⁹⁰Sr durch verschiedene Sommerrapsgenotypen aus kontaminiertem Boden wurde geprüft. Statistisch gesicherte Unterschiede bei der Aufnahme von Radionukliden zwischen den Genotypen konnten festgestellt werden. Die Aufnahme von ¹³⁷Cs und ⁹⁰Sr ist bei den einzelnen Sorten nicht gleichsinnig. Nur ein geprüfter Genotyp nahm sowohl geringe Mengen von ¹³⁷Cs, als auch von ⁹⁰Sr auf. Die mittleren jährlichen Schwankungen in der Radionuklidaufnahme waren größer, als die Unterschiede zwischen den Genotypen.     

Atmospheric nitrate deposition and the microbial degradation of cellobiose and vanillin in a northern hardwood forest

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.     

The use of environmental radionuclides as tracers in soil erosion and sedimentation investigations: recent advances and future developments

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.     

Kinetics of 110mAg, 60Co, 137Cs and 54Mn Bioaccumulation from Water and Depuration by the Crustacean Daphnia Magna

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, for^110mAg, 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.