Determination of Total Iodine in Soils by Inductively Coupled Plasma Mass Spectrometry

A method for the determination of the total amount of iodine in soil by inductively coupled plasma mass spectrometry was developed. Iodine in soil was completely extracted by heating a mixture of 5 mL of 5% tetramethylammonium hydroxide solution and 100 mg of soil for 3 h in an oven at 70°C. Indium as an internal standard was added and the extract was diluted at least more than 10-fold. Iodine amount in the solution was determined by measuring the signal intensity of ¹²⁷I against that of ¹¹³In. When the method was tested by analyzing four reference soil samples (GSS-1, 4, 5, and 7), the iodine contents obtained were in good agreement with the certified values for the samples.     

Identification of organically bound iodine in soil humic substances by size exclusion chromatography / inductively coupled plasma mass spectrometry (SEC / ICP-MS)

Abstract

Sulfur transformation in riee rhizosphere was investigated. Soil enzyme arylsulfatase in rhizosphere and non-rhizosphere soil, whieh is responsible for mineralization of organic sulfur to sulfate sulfur, was studied. The Michaelis constants of arylsulfatase from Maahas c1ay and Pila c1ay loam were 3.04 × 10^-4 M and 3.97 × 10^-4 M, respectively. The arylsulfatase of rhizosphere soil showed higher activity than that of non-rhizosphere soil. Applieation of sulfate had no marked elTect on the enzyme aetivity either in rhizosphere or non-rhizosphere soil under the submerged condition. This indieates that arylsulfatase activity under the submerged condition is not inhibited by applieation of sulfate. The amount of HI-reducible sulfur in the rhizosphere and non-rhizosphere soi! inereased with time. However, rhizosphere soil had a higher amount of HI-reducible sulfur than did non-rhizosphere. Thc ditl'erence in arylsulfatase activity between the rhizosphcre and non-rhizosphere soil was not directly associated with thc number of sulfur-redueing and -oxidizing bacteria.     

中国某些土壤中的水溶性稀土元素

Water-soluble rare earth elements (WSREEs) of four typical soil profiles in China were determined by using a high-resolution inductively coupled plasma mass spectrometer. Results showed that the contents of WSREEs decreased from upper layer to lower layer of soils in the southern part of China with a high rainfall and low pH but increased for soils in the northern part of China with a low rainfall and relatively higher pH. Contents of WSREEs in soils were lower than 100 μg kg^-1 in most cases, and varied greatly with both different soils and different layers of the same profile. The highest content was 2816.3 μg kg^-1 but the lowest was 17.6 μg kg^-1 only. The content of individual rare earth lement (REE) in the soil solution also varied greatly with the highest one ranging from 8.4 to 1373 μg kg^-1 for Ce and the lowest one from 0.05 to 4.48 μg kg^-1 for Lu. The sum of WSREEs in the first soil layers ranged from 121.5 to 345.6 μg kg^-1. Great variations existed among ratios of REEs extracted with water to the total REEs of soils, ranging from 0.02×10^-3 to 13.2×10^-3. But as the upper layer was considered, the ratio showed only a small difference, ranging from 0.79×10^-3 to 1.69×10^-3.     

电感耦合等离子体质谱法测定土壤中的总碘

采用碱液热浸提法处理土壤样品,通过电感耦合等离子体质谱法(ICP-MS)测定土壤中碘元素的总量。对前处理的3大参数——碱度、温度和时间进行试验摸索,得出适用于土壤的最佳浸提条件。测定结果显示,该方法的线性范围为0~500μg/L,线性相关系数0.999 8,方法检出限0.12μg/g,加标回收率为91.0%~104%,RSD均小于5%。综上,该法是一种能够快速、灵敏、准确地测定土壤样品中碘元素的先进方法。     

Fixed ammonium determination in some clay soils

Abstract

We have shown that the traditional Kjeldahl method applied to clay soils of the Duero Basin (Spain) is not effective; so, it is necessary to add HC1 + HF to free trapped ammonium. This fixed ammonium has been measured by two methods which give significantly different results. The level of fixed ammonium in cultivated clay soils is relatively high (it ranges from 180 to 490 ppm). Fixed ammonium is significantly correlated to clay content and total inorganic nitrogen of the soil. A proposed method of analysis for total N is given.     

Ability of some Norwegian soils to supply grass with potassium (K) - soil analyses as predictors of K supply from soil

Abstract. Uptake in grass crops of ammonium acetate lactate extractable K (K_AL) and reserve K (interlayer K + structural K) in soil was studied in 16 field experiments at different locations on a range of mineral soil types in Norway. The K uptake from soil, both from K_AL and reserve K, was considerable, often even at the highest level of K fertilizer. During three years, only on the sandy soils with a low level of acid soluble K (K_HNO3 minus K_AL) was there a yield response to K fertilization. The K_AL values declined rapidly and flattened off at a 'minimum level' which differed with soil type. This minimum level for K_AL is a useful parameter in fertilizer planning, because the grass usually took up the K in excess of the minimum level over two years. The minimum value of K_AL was significantly correlated with the content of clay + silt in soil. The decrease in K_AL during the growing season was closely correlated to the K_AL value in spring minus the minimum value and, therefore, the amount of K supplied to the grass from the K_AL fraction can be calculated. Furthermore, the K_AL value for the following spring may be estimated. The release from reserve K was partially related to acid soluble K.     

Boron adsorption characteristics of some acidic alluvial soils in relation to soil properties

Abstract

We investigated boron (B) adsorption characteristics for 16 acid alluvial soils as a function of equilibrium B concentration (0–80 μg/mL) and the effect of soil properties on such adsorption. The adsorption data for the soils could be described by Freundlich, Temkin, and BET isotherm equations over the entire concentration ranges studied, and by Langmuir and Eadie‐Hofstee equations only over a limited range. In general, the B adsorption capacity and the energy of retention of the soils calculated from different equations are low, the average Langmuir adsorption maxima and bonding energy constant being 21.47 μg/g and 0.113 mL/μg, respectively, making B susceptible to leaching losses. Simple and multiple regression analysis show that the adsorption capacities are significantly influenced by organic carbon (C), cation exchange capacity (CEC), and different forms of aluminium (Al) content in soils. The energy related constants are also influenced by the forms of Al in soils. Existence of significant correlations between constants obtained from different equations confirmed the adsorption characteristics of the soils.     

含水率对土壤有机质含量高光谱估算的影响

土壤含水率对有机质(soil organic matter,SOM)含量高光谱估算精度有很大的影响。为了探讨SOM高光谱估算中土壤含水率的影响,该文对烘干土、风干土和质量含水率为5%~40%(按5%递增)的土壤样本进行了室内高光谱测量,对光谱数据进行了反射率、反射率一阶导数和反射率倒数对数3种光谱数据变换,运用偏最小二乘回归法(partial least squares regression,PLSR)建立了相应的SOM估算模型。结果表明,风干土的SOM高光谱估算精度较好;当含水率水平小于25%时,SOM估算模型精度受含水率的影响较大,光谱数据进行反射率倒数对数变换后的模型精度最高;当含水率水平大于等于25%时,水分对土壤光谱反射率的影响要大于SOM,不适宜利用土壤光谱数据进行SOM含量高光谱估算。该研究可为大田环境不同含水率情况下光谱估算SOM提供参考。     

磷的吸附和表面电荷特征及其与华南地区某些土壤矿物的关系

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.     

土壤磷有效性及其与土壤性质关系的研究

选取我国14个不同地点土样,测定理化性质、全磷、速效磷、水溶性磷含量,采用通径分析研究土壤磷有效性与土壤性质的关系。结果表明,土壤磷有效性是各个土壤性质综合作用的结果。土壤CEC、有机碳、粘粒、砂粒、碳酸钙含量对土壤速效磷比例影响显著,土壤CEC、粘粒、砂粒含量对土壤速效磷比例贡献为正值,而土壤有机碳对土壤速效磷比例贡献为负值;土壤pH和CEC含量对土壤水溶性磷含量影响显著,土壤pH对水溶性磷比例贡献为正值,土壤CEC对土壤水溶性磷比例贡献为负值。本文所选土样基本符合土壤磷有效性与土壤性质之间通径分析的结果。     

Speciation of iodine in soils

In order to analyze the behavior and phytoxicity of iodine in soil, the chemical forms of soil iodine must be identified. Therefore, a method for quantitative speciation of iodine in soil was proposed. Iodine extracted from soil samples with tetrametBPyIammonium hydroxide (TMAH) was separated into humic and fnalvic acid fractions at pH4 1.5 after the addition of ascorbic acid into the TMAH extract to reduce iodate into iodide. Since the iodide in the TMAH extract was recovered in the fdvic acid fraction by this procedure, iodine contained in the haamic acid fraction was considered to be organically bound. Podine in the fulvic acid fraction was separated into organic iodine bound to fnlvic acids and the total inorganic iodine. Furthermore, iodine soluble from soil in 0.1 mol L^-1 potassium chloride was assumed to correspond to the amount of total iodide in soil, and from the difference in the concentration of total inorganic iodine and soluble iodide, the amount of iodate was calculated. By the application of this method, iodine in soil was separated into four fractions: organic iodine bound to humic acids, organic iodine bound to fulvic acids, iodate, and iodide. This speciation method was applied to two soils. It was found that s Barge proportion of iodine in soil occurred in an organicalPy bound form.     

Some Physico-chemical characteristics of soils influenced by Taal Volcano in reference to soil productivity

Soils of the northwestern part of the Taal Volcano in the Philippines representing four geomorphological units (upper, middle, and lower slopes and alluvial plains) were investigated and related to soil productivity. Results revealed that the soils on the upper and middle slopes contained higher amounts of organic matter and available P and displayed a low P retention together with more favorable physical properties such as loamy soil texture, loose and friable and well-drained soils compared to those on the lower slopes and in the alluvial plains. Due to these favorable soil characteristics, sustained agricultural production was higher at the upper elevations than at the lower elevations. Year-round multistorey / mixed cropping systems of cultivation in the upper and middle landscapes were also made possible because the higher precipitation was evenly distributed coupled with cooler temperatures compared the conditions on the lower slopes and in the alluvial plains. On the other hand, the soils on the lower slopes and in the alluvial plains had a clayey texture and contained a lower amount of organic matter and available P, in addition to the lower precipitation, resulting in reduced land utilization, as indicated by the limited types of crops grown and lower yield of crops.     

湘北红壤丘岗稻田土壤有机碳、养分及微生物生物量空间变异

通过对湘北典型红壤丘岗254个稻田耕层样(01～8.cm)进行分析,比较了微地形对稻田土壤有机碳、氮、磷和微生物生物量的影响。结果表明,丘岗底部稻田土壤有机碳、全氮、微生物生物量碳、微生物生物量氮、可溶性氮含量分别比丘岗中下部稻田高14.6%1、3.6%、24.6%、20.4%和95.8%,丘岗中下部稻田土壤Olsen-P含量比丘岗底部稻田高33.3%,差异均达极显著水平(P0.01)。不同部位稻田土壤全磷、微生物生物量磷含量和有效磷库(微生物生物量磷与Olsen-P之和)含量差异不显著。此外,丘岗底部稻田土壤碳磷比、微生物生物量碳磷比和微生物商比丘岗中下部稻田高12.7%,28.5%,8.2%,其差异达显著(P0.05)或极显著(P0.01)水平。但微生物生物量氮/全氮、微生物生物量磷/全磷、土壤碳氮比和微生物生物量碳氮比差异不显著。     

Phosphate eesoeption isotherms in four selected tropical soils and one temperate soil

Abstract

Some problem areas connected with soil testing and with reporting soil test and plant analysis results are explored, A uniform system for reporting soil test results is suggested as a step towards further standardization of soil test methods within and among states. Four categories are suggested as a common terminology for soil test and plant analysis results. These are: deficient, probable response, adequate and excessive.     

Metals in urban soils of Sevilla: seasonal changes and relations with other soil components and plant contents

Soils of the urban area of Sevilla have been scarcely studied, especially concerning their concentrations of potentially toxic metals. A previous paper has shown that moderate pollution exists in soils from some public green areas of the city, and a common pattern was found in the distribution of the concentrations of some particular metals. The present paper is aimed at (i) determining possible seasonal changes in the measured concentrations; (ii) checking possible effects of the observed pollution on plant metal contents, and (iii) finding possible relations between metals by statistical techniques. Samples of 35 soils from the urban area of Sevilla were studied. Comparison with previous data shows that samples from a depth of 0–20 cm are representative of the measured soil properties for the city. We show that in most cases differences in the EDTA‐ and aqua regia‐extractable metal contents between autumn 2000 and summer 2001 are not significant. Only Zn shows significant decreases (P < 0.05), probably because it is more mobile than the other metals studied. Electrical conductivity and pH also show significant changes related to leaching of soluble salts. We found a strong association between ‘urban’ metals (as defined in the literature) and organic matter, as shown by factor analysis, whereas ‘non‐urban’ metals could be related to clay and carbonate contents, perhaps coming from the soil parent materials. The behaviour of the urban metals means that organic matter contributes to their accumulation, either by retention of the incoming metals from the atmosphere, dust or various human activities, or from addition of organic amendments that might provide significant amounts of such metals. Although concentrations of Cu, Pb and Zn at several sites exceeded the limits established elsewhere as acceptable in residential areas, the values in the grass were less than those considered as normal in the literature. This implies that fairly large concentrations in the soil do not necessarily make metals more available.     

Effects of liming on soil magnesium on some soils in New Zealand

Abstract

Results from 2 pastoral field lime trials showed that liming reduced exchangeable Mg. This effect increased with increasing rate of lime and with time following lime application, and was greatest in the top 0–50 mm depth. Soil solutions, sampled 2 years after liming, showed that solution Mg increased in increasing rate of lime. This effect was greatest in the top 20 mm of soil.

Lime incubation studies indicated that Mg fixation did occur on some of the soil studied, at pH >6.2. However, this did not account for the size of the observed effects of liming on exchangeable Mg in the field or explain the observed effects of liming at pH <6.2.

It is suggested therefore, that the major mechanism by which liming reduces exchangeable Mg, on these soils, is through displacement of exchangeable Mg into solution by the added Ca in lime, and subsequent leaching.

Results from other field trials suggest that liming will decrease exchangeable Mg if the change in pH‐dependent CEC (?ECEC) per unit change in soil pH is <15 me 100 g‐¹.     

辣椒叶片生理特性对光照强度和土壤水分的响应

以辣椒为研究对象,研究了不同光照强度和土壤水分对辣椒叶片相对含水率（RWC）、叶绿素（Chl）含量、保护酶活性以及游离脯氨酸和丙二醛（MDA）含量的影响。结果表明：1）随着遮阴程度和土壤水分的增加,叶片RWC,叶绿素含量均呈上升趋势,土壤水分增加主要有利于叶绿素a含量的增加,遮阴主要有利于叶绿素b含量的增加。类胡萝卜素含量随遮阴程度的增加和土壤水分的降低而下降。MDA含量在干旱胁迫条件下升高,随着遮阴程度的增加呈先降后升的趋势。光照相同,在干旱和高水条件下,保护酶活性和脯氨酸含量均表现出不同程度的上升;水分条件相同,保护酶活性和脯氨酸含量均随遮阴程度的增加而下降,且保护酶对光照强度的敏感性为SOD＞CAT＞POD。2）保护类物质（脯氨酸与保护酶）与伤害类物质（MDA）均达到了极显著正相关,膜保护酶与叶绿素含量达到了极显著负相关。综合以上认为,将遮阴30%和土壤相对含水率为70%～85%作为适宜的遮阴和灌溉指标是科学合理的。     

Arsenic in field‐collected soil solutions and extracts of contaminated soils and its implication to soil standards

Large concentrations of arsenic in soils, sediments, and freshwaters require risk assessment across the Central Alps and other regions. We measured arsenic concentrations in soil samples collected from 38 sites located in the Austrian Central Alps that had been contaminated due to mining and smelter activities and geogenic mineralization. Medians and ranges of arsenic concentrations (in mg kg^—1) in the soil solid phase were: 77.1 (1—3000) for the total (As_t), 19.2 (0—726) for (NH₄)₂C₂O₄‐extractable (As_o), 2.35 (0—169) for (NH₄)₂HPO₄‐extractable (As_p), and 0.143 (0—11.1) for (NH₄)₂SO₄‐extractable (As_s) arsenic. Arsenic concentrations in soil solutions (As_sol) collected from organic surface layers and mineral horizons at five selected sites using suction cups fitted with nylon membranes ranged from 0 to 171 μg l^—1. Typically, the prevailing species of As in the soil solution was As(V). As_sol was correlated with As_s (As_sol = 0.279 + 15.6 As_s; r² = 0.938; n = 17) and As_t (As_sol = 1.272 + 0.043 As_t; r² = 0.833; n = 17). Using these empirical models, As_sol can be predicted quite accurately based on extraction with 0.05 M (NH₄)₂SO₄ or total arsenic concentrations in the soil. Linking these models to drinking water standards (DWS) we propose soil standards for freshwater protection that vary for As_s (mg kg^—1) between 0.62 (for DWS = 10 μg l^—1 WHO) and 3.19 (for DWS = 50 μg l^—1). Corresponding standards for As_t (mg kg^—1) are 203 (DWS = 10 μg l^—1) and 1133 (DWS = 50 μg l^—1). These considerations demonstrate that changes in legislation on DWS may have dramatic impact on As concentrations in soil that are acceptable for groundwater protection.     

长期施肥对栗褐土有机碳含量及其组分的影响

【目的】作为土壤质量的重要指标,土壤有机碳及其组分在耕地生产力和作物产量方面发挥着重要作用。本文以25年长期定位施肥试验为依托,分析了不同施肥处理对栗褐土有机碳含量及其组分的影响,为调控农田土壤肥力及栗褐土有机碳库的管理提供科学依据。【方法】田间试验开始于1988年,设置8个施肥处理为不施肥(CK);单施氮肥(N);氮磷肥合施(NP);单施低量有机肥(M1);低量有机肥与氮肥合施(M1N);低量有机肥与氮磷肥合施(M1NP);高量有机肥与氮肥合施(M2N);高量有机肥与氮磷肥合施(M2NP)。于第25年玉米播种前,采集以上处理的耕层(0—20 cm)土壤样品。借助有机碳物理分组方法和化学分析方法,测定了土壤总有机碳和有机碳各组分的含量。【结果】长期施用不同肥料不同程度地提高了栗褐土总有机碳、游离态颗粒有机碳以及闭蓄态颗粒有机碳含量,其中有机肥与化肥配施尤其是高量有机肥与化肥配施的作用更加明显。与不施肥相比,高量有机肥与无机肥配施(M2N、M2NP)总有机碳含量增加了121.1%、166.8%,游离态颗粒有机碳增加了239.2%、359.2%,闭蓄态颗粒有机碳增加了288.4%、289.9%。单施氮肥(N)及有机肥与氮磷肥配施(M1NP、M2NP)可显著提高矿物结合态有机碳含量,增幅分别为27.8%、34.8%、33.3%。不施肥条件下,栗褐土有机碳中颗粒有机碳与矿物结合态有机碳所占的比例相当,长期施肥提高了颗粒有机碳特别是闭蓄态颗粒有机碳的比例,降低矿物结合态有机碳所占的比例,闭蓄态颗粒有机碳成为栗褐土有机碳的主要贮存库。相关分析表明,长期施肥条件下栗褐土游离态、闭蓄态颗粒有机碳含量之间及其与总有机碳含量之间均呈极显著正相关,矿物结合态有机碳含量与总有机碳及其他组分的有机碳之间均无明显相关。【结论】化肥、有机肥以及有机肥与化肥配施能够提高栗褐土游离态颗粒有机碳、闭蓄态颗粒有机碳以及总有机碳含量。高量有机肥与化肥配施更有助于栗褐土游离态、闭蓄态颗粒有机碳的积累,有利于土壤养分有效性的提高和有机碳品质的改善。氮肥单施、有机肥与氮磷肥配施则是提高矿物结合态有机碳含量的有效措施。     

我国主要类型土壤的有效态硒及其与某些土壤性质的关系

Forty-eight soil profiles were sampled from different ecological and pedogeochemical areas of China and their available selenium (Av-Se) contents were determined. Results showed that the content of Av-Se in the profiles of soils in China ranged within 2.49~18.10 μg kg^-1, with a mean value of 10.01 μg kg^-1, and was in the sequence of Ferralisols > Luvisols > Isohumisols > Aridisols. The correlation analysis between Av-Se and the soil physical-chemical properties revealed that the correlations between Av-Se and O.M., CEC, Fe₂O₃, Al₂O₃, ignition loss, Co and Zn were positive at a highly significant level, but those between Av-Se and pH, base saturation, CaO, Ba and Sr were all negative at a highly significant level. The reason of some diseases related to the Se deficiency might be the leaching loss of selenium in some soils.