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     

用电导频散法研究Cl-、SO2-4和H2PO-4阴离子与土壤的相互作用

本文介绍了采用电导频散装置测量分别含有10-4mol/L HCl、5×10-5mol/LH2SO4和10-4mol/L H3PO4的黄棕壤、棕壤、黑土和砖红壤悬液(20-30g/kg)的电导频散曲线,频散曲线上均呈现频率范围相当宽的坪区.频散曲线的特性分析结果表明,黄棕壤和棕壤在3种酸溶液中的始散频率(0.6-1kHz)低于黑土悬液(16-28kHz),而砖红壤的始散频率最高(25-47kHz);Cl-、SO2-4和H2PO-4离子与4种土壤的相对亲合力(REC1.5/REC2-1)顺序为Cl-＜SO2-4＜H2PO-4,在不同土壤之间的顺序则随酸溶液而异.     

可变电荷土壤对SO42-的吸附

本文研究了三种带可变电荷的红壤在恒定pH和Cl^-离子存在条件下对SO₄^2-的吸附.三种红壤的OH^-释放量分别仅占SO₄^2-吸附量的12%,14%和20%.砖红壤在pH5.0时的电荷变化占所吸附的SO₄^2-的64-82%.作者认为大部分SO₄^2-以置换水合基的方式被吸附.     

Cl-、SO42-在酸性土壤中对铝电极电位的影响及其差异

盐分是土壤腐蚀的一个重要影响因素,业已证明,土壤盐分尤其有Cl^-存在时,能加速土壤腐蚀反应^[1,2]。Cl^-、SO₄^2-是土壤中常见的盐分阴离子,它们不但能破坏金属表面的氧化膜,同时由于Cl^-、SO₄^2-都具有特性吸附能力,有可能直接参与腐蚀反应过程。     

3 种挺水植物吸收水体NH4+、NO3-、H2PO4- 的动力学特征比较

本文用动力学试验研究了具有景观价值的3 种挺水植物—— 水生美人蕉(Canna generalis)、细叶莎草(Cyperus papyrus)、紫芋(Colocasia tonoimo)对H₂PO₄^-、NH₄⁺、NO₃^- 的吸收特征及差异。试验结果表明: 3 种挺水植物吸收H₂PO₄^- 时, 美人蕉的吸收速率最快, 且在较低离子浓度条件下也可以吸收该离子, 说明其具有嗜磷特性, 能够适应广范围浓度H₂PO₄^- 环境; 吸收NO₃^- 时, 细叶莎草的速率最快, 但对低浓度NO₃^- 环境的适应能力较差, 美人蕉吸收NO₃^- 的特性与细叶莎草刚好相反; 吸收NH₄⁺ 时, 细叶莎草的吸收速率最快, 且在低浓度NH₄⁺ 环境下仍能吸收该离子, 而美人蕉的吸收速率最慢, 但能在低浓度NH₄⁺ 环境下吸收该离子。说明不同植物对养分的吸收特性存在较大差异, 各自的污染水体修复适用范围也不同。美人蕉可用于各种浓度H₂PO₄^- 污染的水体修复; 而NO₃^- 污染严重的水体最适宜用细叶莎草作先锋植物, 修复到一定程度后再种植美人蕉来维持水质; 细叶莎草在各种浓度NH₄⁺ 污染的水体中均适用, NH₄⁺ 污染较轻的水体也可用美人蕉修复。     

土-水体系中电导频散的影响因素

用红壤、赤红壤和砖红壤3种土壤胶体,测定胶体悬液在不同频率时的电导和直流电导,用以观察频散现象。结果表明,各种胶体的电导频散能力因土壤类型而异,红壤最强,赤红壤次之,砖红壤最弱。呈现明显频散所需要的频率,红壤和赤红壤为10千赫左右,砖红壤约为100千赫。可变电荷土壤的类型对电导频散的影响与土壤胶体所带的电荷总量密切相关。对于同一种胶体,悬液相对电导率(某一频率时的电导率与300赫时的电导率之比)随胶体浓度的增加而变大。红壤悬液在各种电解质存在时的电导频散曲线的形状不同,其中KCl者为一斜上直线,Ca(NO₃)₂,和CaCl₂,者则为上翘的曲线。在1到100千赫之间,频散的顺序为:KCl>Ca(NO₃)₂>CaCl₂。呈现明显频散所需要的频率,对KCl者为1千赫左右,Ca(NO₃)₂者约为10千赫,CaCl₂者高达100千赫左右。在同一频率下,红壤胶体悬液的相对电导率随KCl溶液浓度的增加(10^-5—10^-3mol/L)而减小。     

Chemical Behavior of Chromium in Soils: Ⅲ. Mechanism of Cr(Ⅵ) Adsorption by Soils

An analysis of Cr (Ⅵ)-sorbed surface of the soils by using a scanning electron microscope and an electron probe microscope has proved that aluminium is the chief element affecting Cr (Ⅵ) adsoption. As the ionic strength of the solution increased, the amounts of Cr (Ⅵ) adsorbed by goethite and soils decreased. Cr (Ⅵ) adsorption was greatly depressed in the presence of SO₄^2-, WO₄^2-, MoO₄^2-, HPO₄^2- and H₂PO^4- which competed for anion adsorption sites. The depressing extent of these anions was found to follow the sequence: HPO₄^2-, H₂PO^4->MoO₄^2->WO₄^2->SO₄^2->>Cl^-, NO^3-. The amounts of Cr (Ⅵ) desorption varied with different extractants.     

伴随阴离子对马铃薯种植冲击土中钾素固持与淋溶的影响

A column study was carried out to assess the influence of accompanying anions on potassium (K) leaching at potato growing sites with different soil textures (sandy loam and clay loam) in northwestern India. Potassium was applied in the top 15 cm layer of soil column at 30 and 60 mg K kg^-1 through different sources having different accompanying anions (Cl^-, SO₄^2-, NO₃^- and H₂PO₄^-). Maximum K was retained in the top 0--15 cm layer with a sharp decrease in K content occurring in 15--30 cm layer of the soil column. The trend was similar for both levels of applied K as well as frequency of leaching and soil type. The decrease of K content in soil column after four leaching events was maximum in case of Khanaura sandy loam, while only minor decrease was observed in Hundowal clay loam when K was applied at 60 mg K kg^-1, indicating higher potential of clay rich soil to adsorb K. In general, the K leaching in presence of the accompanying anions followed the order of SO₄^2- ≤ H₂PO₄^2- < NO₃^- = Cl^-. Highest 1 mol L^-1 CH3COONH4-extractable K was retained when K was applied along with SO42- and H2PO4- anions, and the least was retained when accompanying anion was Cl^-1. The influence of anions was more pronounced in the light textured soil and at high amounts of K application. Higher levels of K application resulted in higher losses of K, especially in sandy loam soil as observed from the leachate concentration. Among the different K sources, the maximum amount of K leaching was noticed in the soil column amended with KCl. After four leachings, the maximum amount of K leached out was 6.40 mg L^-1 in Hundowal clay loam and 9.29 mg L^-1 in Khanaura sandy loam at 60 mg K kg^-1 of soil application through KCl. These concentrations were lower than the recommended guideline of the World Health Organisation (12.00 mg L^-1).     

影响土壤镉吸持和解吸的因子

研究了土壤的pH、离子浓度(0.01mol/L、0.05mol/L、0.1mol/L)、阴(阳)离子种类(NO₃^-、Cl^-、OAc^-、SO₄^2-、HPO₄^-及Zn和Pb)及石灰和葡萄糖对土壤镉吸持及其解吸的影响。     

塔里木盆地西南缘典型灌区土壤盐渍化特征分析——以塔吉克阿巴提镇为例

在野外GPS定点定位调查、土壤样品分析的基础上,借助Excel和ArcGIS9.3等软件,对新疆自治区喀什市岳普湖县塔吉克阿巴提镇0-30cm土层的盐离子特征、灌区土壤盐渍化现状及空间分布特征进行了分析。结果表明,0-30cm土层土壤中的离子以Cl^-,SO₄^2-,Na⁺,Ca²⁺为主Na+与Cl^-呈极显著正相关关系,相关系数为0.98,HCO₃^-与其它6种离子(Na⁺,Ca²⁺,Mg²⁺,K⁺,Cl^-,SO₄^2-)呈负相关关系受灌排系统影响较大的农田0-30cm土壤中Cl^-/SO₄^2-比值远小于不受灌排系统影响的荒地农田和荒地0-30cm土壤中的Cl^-/SO₄^2-比值与总盐呈正相关关系,相关系数依次为0.68和0.32。现阶段对塔吉克阿巴提镇灌区农业危害最严重的是氯化物-硫酸盐盐渍化土,硫酸盐盐渍化土表现为盐渍化土地向非盐渍化土地转变的过渡类型非盐渍化农田及轻度盐渍化农田主要分布在开垦较早,灌排系统畅通的区域,灌排系统不畅通的区域仍然处于脱盐缓慢或持续积盐的状态。     

阴离子对可变电荷土壤吸附铜离子的影响机理

根据NO-3、Cl-和SO24-对可变电荷土壤和恒电荷土壤吸附Cu2+的影响的比较,探讨了阴离子对可变电荷土壤吸附Cu2+的影响机理。结果表明,当3种阴离子的浓度相同时,在SO24-体系中铁质砖红壤对Cu2+的吸附率较在NO3-和Cl-体系中大得多,而在浓度相同的3种阴离子体系中,黄棕壤对Cu2+的吸附率相差不大。在离子强度相近的NaCl体系中,砖红壤对Cu2+的吸附率相近。在3种阴离子体系中,随着pH升高,砖红壤对Cu2+的吸附率均增大;但在NO-3体系和Cl-体系中Cu2+的吸附率相近;而在SO24-体系中Cu2+的吸附率最大。随着Na2SO4浓度的增大,铁质砖红壤和砖红壤对Cu2+的吸附率减小。但在0.005 mol L-1和0.05 mol L-1Na2SO4体系中,Cu2+的吸附率大于在不含Na2SO4的体系中者。而在0.5 mol L-1Na2SO4体系中,Cu2+吸附率小于在不含Na2SO4体系中者。在3种浓度的Na2SO4体系中,黄棕壤对Cu2+的吸附率均小于在不含Na2SO4体系中者。总之,阴离子可通过离子强度、专性吸附和形成离子对影响土壤对Cu2+的吸附。在可变电荷土壤中,阴离子对Cu2+吸附的影响机理较在恒电荷土壤中复杂得多。     

双阻NH4+选择性微电极测定水稻叶片细胞中NH4+的活度

本文介绍了双阻NH4+选择性微电极的制作方法、工作原理及操作方法。微电极电位响应値与溶液中NH4+的活度呈对数曲线的关系,NH4+选择性微电极与其他类型的电极(如H+、NO3-)最大区别是K+的干扰,在含有72 mmol/L K+的标定溶液中,电极标定曲线的斜率为48~58 mV,对NH4+的检出限小于10-4 mol/L,说明电极对NH4+有较高的选择性,受K+的影响较小,可以用来测定。用以测定2.5 mmol/L NH4+培养2周的水稻叶片,结果表明,叶片细胞中NH4+活度分布在高低不同的两个区间内,分别代表了细胞质和液泡中的测定,水稻叶片细胞质和液泡NH4+的活度分别为2.58~9.30 mmol/ L和11.36~25.20 mmol/L。水稻叶片组织中的NH4+主要来自液泡,流动分析仪测定的水稻叶片组织的NH4+浓度为11.12 mmol/L。NH4+选择性微电极为研究水稻对NH4+的吸收利用提供了技术支撑。     

Effects of nitrogen fertilization on soil nitrogen pools and microbial properties in a hoop pine (Araucaria cunninghamii) plantation in southeast Queensland, Australia

A field study was conducted to investigate the effects of N fertilization on soil N pools and associated microbial properties in a 13-year-old hoop pine (Araucaria cunninghamii) plantation of southeast Queensland, Australia. The treatments included: (1) control (without N application); (2) 300 kg N ha^-1 applied as NH₄NO₃; and (3) 600 kg N ha^-1 as NH₄NO₃. The experiment employed a randomized complete block design with four replicates. Soil samples were taken approximately 5 years after the N application. The results showed that application of 600 kg N ha^-1 significantly increased concentrations of NH₄⁺-N in 0-10 cm soil compared with the control and application of 300 kg N ha^-1. Concentrations of NO₃^--N in soil (both 0-10 cm and 10-20 cm) with an application rate of 600 kg N ha^-1 were significantly higher compared with the control. Application of 600 kg N ha^-1 significantly increased gross N mineralization and immobilization rates (0-10 cm soil) determined by ¹⁵N isotope dilution techniques under anaerobic incubation, compared with the control. However, N application did not significantly affect the concentrations of soil total C and total N. N application appeared to decrease microbial biomass C and N and respiration, and to increase the metabolic quotient (qCO₂) in 0-10 cm soil, but these effects were not statistically significant. The lack of statistical significance in these microbial properties between the treatments might have been associated with large spatial variability between the replicate plots at this experimental site. Spatial variability in soil microbial biomass C and N was found to relate to soil moisture, total C and total N.     

黄棕壤添加重金属的毒性评价及其临界浓度确定

在连续盆栽水稻、小麦的过程中研究了加入黄棕壤的Cu、Cd、Pb的毒性(发光细菌法)。结果表明,当以水提取黄棕壤中三元素,浓度低,不显毒性,这与水提取红壤的结果相反;当以0.1mol L^-1HCI提取黄棕壤中三元素,则浓度明显提高而显示毒性。在相关显著水平P=0.001的基础上建立了土壤金属浓度与剩余发光度(毒性指标)优化拟合方程。规定含金属土壤的临界剩余发光度为90%(EC₁₀)。据此,估算出黄棕壤中Pb、Cu、Cd的临界浓度(μg/g土)分别为:488-587,17.8-25.3,2.11-2.12。     

Effects of elevated carbon dioxide concentration on biological nitrogen fixation, nitrogen mineralization and carbon decomposition in submerged rice soil

Controlled-environment chambers were used to study the effects of elevated CO₂ concentrations on biological N fixation, N mineralization and C decomposition in rice soil. In three chambers, CO₂ concentration was maintained at 353ᆣ/396ᆫ µmol mol^-1 (day/night; ambient CO₂), while in another three, CO₂ was maintained at 667ᆸ/700ᆽ µmol mol^-1 (day/night; elevated CO₂) throughout the growing season. Rice (var. Nipponbare) seedlings were grown under either ambient or elevated CO₂ concentrations, and then transplanted into the soils in the corresponding chambers. At different growth stages, soil samples were taken from surface (0-1cm) and sub-surface (1-10cm) layers at the centre of four hills, then sieved (<1 mm) to remove root residues. Fresh soil was used to measure N fixation activity (using the acetylene reduction assay), NH₄⁺ content and organic C. Separate sets of soil samples were transferred to serum bottles and anaerobically incubated at 30°C for 30 days to measure potential rates of N mineralization and C decomposition. Under an elevated atmospheric CO₂ concentration, acetylene reduction activity significantly increased in the surface soil layer during the early cultivation stages and in the sub-surface soil layer during the latter part of cultivation. There was no difference in the amount of NH₄⁺ in fresh soils between elevated and ambient CO₂ chambers, while the rate of N mineralization was increased by elevated CO₂ during the latter part of cultivation. Soils from the elevated CO₂ chambers had obviously higher rate of C decomposition than that from the ambient CO₂ chambers. CH₄ production gradually increased with the growth of rice plants. These results suggest that elevated CO₂ affected biological N fixation, N mineralization and C decomposition in submerged rice soil during the different growth stages of rice.     

Denitrification, N2O and CO2 fluxes in rice-wheat cropping system as affected by crop residues, fertilizer N and legume green manure

Use of renewable N and C sources such as green manure (GM) and crop residues in rice-wheat cropping systems of South Asia may lead to higher crop productivity and C sequestration. However, information on measurements of gaseous N losses (N₂O+N₂) via denitrification and environmental problems such as N₂O and CO₂ production in rice-wheat cropping systems is not available. An acetylene inhibition-intact soil core technique was employed for direct measurement of denitrification losses, N₂O and CO₂ production, in an irrigated field planted to rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in an annual rotation. The soil was a coarse-textured Tolewal sandy loam soil (Typic Ustochrept) and the site a semi-arid subtropical Punjab region of India. Wheat residue (WR, C:N=94) was incorporated at 6 t ha^-1 and sesbania (Sesbania aculeata L.) was grown as GM crop for 60 days during the pre-rice fallow period. Fresh biomass of GM (C:N.=18) at 20 or 40 t ha^-1 was incorporated into the soil 2 days before transplanting rice. Results of this study reveal that (1) denitrification is a significant N loss process under wetland rice amounting to 33% of the prescribed dose of 120 kg N ha^-1 applied as fertilizer urea-N (FN); (2) integrated management of 6 t WR ha^-1 and 20 t GM ha^-1 supplying 88 kg N ha^-1 and 32 kg FN ha^-1 significantly reduced cumulative gaseous N losses to 51.6 kg N ha^-1 as compared with 58.2 kg N ha^-1 for 120 kg FN ha^-1 alone; (3) application of excessive N and C through applying 40 t GM ha^-1 (176 kg N ha^-1) resulted in the highest gaseous losses of 70 kg N ha^-1; (4) the gaseous N losses under wheat were 0.6% to 2% of the applied 120 kg FN ha^-1 and were eight- to tenfold lower (5-8 kg N ha^-1) than those preceding rice; (5) an interplay between the availability of NO₃^- and organic C largely controlled denitrification and N₂O flux during summer-grown flooded rice whereas temperature and soil aeration status were the primary regulators of the nitrification-denitrification processes and gaseous N losses during winter-grown upland wheat; (6) the irrigated rice-wheat system is a significant source of N₂O as it emits around 15 kg N₂O-N ha^-1 year^-1; (7) incorporation of WR in rice and rice residue (C:N=63) in wheat increased soil respiration, and increased CO₂ production in WR- and GM-amended soils under anaerobic wetland rice coincided with enhanced rates of denitrification; and (8) with adequate soil moisture, most of the decomposable C fraction of added residues was mineralized within one crop-growing season and application of FN and GM further accelerated this process.     

Biological dinitrogen fixation and soil microbial biomass carbon as influenced by free-air carbon dioxide enrichment (FACE) at three levels of nitrogen fertilization in a paddy field

An experiment was conducted in an Andosol paddy field in Shizukuishi (Iwate Prefecture, Japan) to determine the effects of free-air CO₂ enrichment (FACE) on biological N₂-fixation activity and soil microbial biomass C at three levels of N application. Rice (Oryza sativa L. cv. Akitakomachi) plants were grown under ambient CO₂ or FACE (ambient +200 µmol mol^-1 CO₂) conditions throughout the growing season with each treatment having four replicated plots. Three levels of N fertilizer (high, standard and low; 15, 9 and 4 g N m^-2, respectively) were applied to examine the effect of different N availability under both CO₂ conditions. Soil samples were collected at four different times from upper and lower soil layers (0-1-cm and 1-10-cm soil depths, respectively) and analysed for biological N₂-fixation (BNF) activity and microbial biomass C (MBC) by the acetylene reduction and chloroform fumigation-extraction methods, respectively. The amounts of chlorophyll-type compounds (Chls), an index of algal growth, and soil available C were also determined. Compared to the ambient CO₂ treatment, the FACE treatment had significantly higher BNF activity in both the upper and lower soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. MBC was significantly increased by FACE in both the upper and lower soil layers from the middle to later period of the growing season compared to the ambient CO₂ treatment. The FACE treatment increased the Chls in the upper soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. The amount of soil available C was not significantly different between FACE and ambient CO₂ treatments in both the upper and lower soil layers throughout the cropping season. From these results it can be concluded that the FACE treatment had a significantly positive influence on BNF activity, MBC and Chls at different levels of N fertilization rates in paddy field during the cropping season.     

2-Keto-4-methylthiobutyric acid-dependent biosynthesis of ethylene in soil

2-Keto-4-methylthiobutyric acid (KMBA) has been identified as an intermediate in methionine-derived ethylene (C₂H₄) biosynthesis by microbial cultures. This study was designed to assess the effectiveness of KMBA as an C₂H₄ precursor in soil. Gas chromatographic analysis indicated that amendment with KMBA (up to 10 mM) stimulated the biosynthesis of C₂H₄ in two Pakistani soils. Results also revealed that substrate- (KMBA)-dependent C₂H₄ production was inhibited when the soils were amended either with glucose (as a C source), NH₄NO₃ (N source) or antibiotics. The KMBA-derived C₂H₄ biosynthesis in both soils was maximum when the soil suspension was amended with 10 mM substrate and incubated at pH 7.5 for a period of 120 h at 35°C with shaking. Comparison of soils revealed that C₂H₄ production was relatively greater in a silty clay loam S₁ (containing 1.15% organic C) soil compared to a loamy S₂ (containing 0.54% organic C) soil. KMBA was found to be an equally effective substrate of C₂H₄ when compared with another intermediate, 1-aminocyclopropane-1-carboxylic acid (ACC), whereas, f-ketglutaric acid failed to serve as an C₂H₄ substrate in soil. As far as we know, this is the first study reporting KMBA-dependent C₂H₄ production in soil.     

CO2与NH4+/NO3-比互作对番茄幼苗培养介质pH、根系生长及根系活力的影响

为探讨CO2浓度升高能否减缓高浓度NH4+-N对番茄根系的毒害作用,本试验在营养液栽培条件下,以番茄为材料,在CO2生长箱中研究2个CO2浓度与5个不同NH4+/NO3-配比的交互作用对生长介质的pH、根系生长及根系活力的影响。结果表明,随着生育期的推进与CO2浓度的升高,pH变化幅度增大。两个CO2浓度均表现为全NO3--N含量营养液的pH呈上升趋势,其它处理营养液的pH均呈现出不同程度的下降趋势,下降的幅度随NH4+/NO3-比例的增加而增加;而且全NH4+-N引起pH值下降的程度大于全NO3--N引起pH增加的程度。CO2浓度升高增加了低NH4+/NO3-比例供应处理的蕃茄幼苗冠干重、根干重、根系活力、根系总吸收面积、活跃吸收面积。这些指标对CO2的响应随NH4+/NO3-比例的降低而加强,冠干重、根干重、根系活力、根系总吸收面积、活跃吸收面积增加分别高达65.8%、78.0%、18.9%、12.9%与18.9%。说明在CO2浓度升高条件下,番茄幼苗根生长潜力在全NO3--N处理中最大,但不能减弱全NH4+-N对番茄根系的毒害作用。