赤果鱼木叶中微量和稀土元素的测定

利用等离子体质谱仪 (ICP MS)测定了赤果鱼木叶中微量元素和稀土元素 ,共测定了 48种元素的含量     

一种利用Profile-1生物发光仪快速测定土壤中微生物量的改良方法

开发了一种利用Profile-1生物发光仪测定土壤中微生物量的改良方法,并以此方法分别测定了标准大肠杆菌茵液以及3种不同类型的土壤(九段沙湿地土壤,崇明东滩大田土壤和崇明实验地改良土壤)的微生物量,并将结果与Profile-1生物发光仪自带的标准分析方法以及传统的菌落计数法进行比较。结果显示,改良的ATP提取方法(BAB改良分析法)和Profile-1生物发光仪自带的标准分析方法都可用于液体样品中微生物量的测定,其灵敏度和准确度无显著差异(P0.05)。但在测定土壤样品时,菌落计数法测定结果大约占BAB改良分析法测定结果的1%～5%,占Profile-1生物发光仪自带的标准分析方法的测定结果的22%～99%。这表明在分析土壤样品时,BAB改良分析法较Profile-1生物发光仪自带的标准分析方法的ATP提取效率更高,可显著提高仪器检测土壤样品的灵敏度和可靠性,因此可有效应用于各类土壤的微生物量的监测,为土壤环境监控提供微生物量的可靠数据。     

时间分辨荧光免疫层析法检测大米中黄曲霉毒素B_1的不确定度分析

对采用时间分辨荧光免疫层析法(TRFIA)测定大米中黄曲霉毒素B1(AFB1)含量的不确定度进行分析,找出影响不确定度的主要分量。根据CNAS GL06—2006《化学分析中不确定度的评估指南》中提供的方法,建立数学模型,分析测定过程中各不确定度分量的来源,并对其进行量化和评定。结果表明,相对标准合成不确定度为3.703%、相对标准总不确定度为7.406%,大米中黄曲霉毒素B_1含量为(5.235 2±0.387 7)μg/kg(k=2)。不确定度主要来源于标准曲线拟合、重复性检测和样品提取,分别占比20.82%、23.27%和19.35%。测定过程中,应首先制备准确且稳定的标准曲线,并增加平行样的测定次数,提高提取操作的准确度。本文所建立的不确定度评定方法可用于TRFIA法测定大米中黄曲霉毒素B_1含量结果的评定。     

赤红壤地区森林土壤球囊霉素相关蛋白测定方法

球囊霉素是丛枝菌根真菌菌丝产生的一种糖蛋白,被证明具有改善土壤结构、固定土壤中重金属、保护有机碳等重要的生态功能。球囊霉素目前尚无法纯化,一般通过测定球囊霉素相关蛋白(GRSP)来对其定量。由于GRSP测定方法的非专一性,目前尚无适宜于各种陆地生态系统的标准测定方法。本文针对GRSP测定结果可能受到提取时间、离心力以及测定前再次离心时离心力的大小等因素的影响,设置对比试验,对亚热带赤红壤地区土壤GRSP提取测定,以期获取适合于该地区的GRSP测定方法。结果表明:当提取时离心时间为10 min,10000×g的离心力提取的易提取GRSP(EE-GRSP)是5000×g提取的1.15~1.82倍,但离心力大小对总GRSP(T-GRSP)影响不显著;当提取时离心力为5000×g时,离心时间由10 min延长至15 min能够显著提高EE-GRSP含量;测定之前对上清液再次离心,若使用较大的离心力(≥10000×g),将显著影响GRSP测定值;经过6次连续提取,能够提取T-GRSP理论最大含量的97.7%~99.8%;因此,在亚热带酸性赤红壤森林生态系统中,GRSP的提取建议采用10000×g 10 min的离心力和离心时间组合,测定前对上清液再次离心时,应以≥10000×g的离心力为宜,研究结果为该地区GRSP的标准化测定提供了理论依据。     

陕北半湿润黄土丘陵区纯林土壤性质极化

在由单一树种组成的纯林内土壤性质偏离原平衡态并朝某个方向极端化发展的趋势被称为极化.采用多样地多样点混合采土法对陕北半湿润黄土丘陵区进入后期成熟生长期的不同树种纯林和混交林土壤性质测定结果表明: (1)几乎所有树种纯林的土壤性质均发生了中度(P＞0.10)以上的极化,其中属于极强度极化(P＞0.20)的性质分别为:落叶松和白桦林地的化学、生物学性质和微量元素;侧柏林地的化学和生物学性质;华山松和辽东栎林地的化学性质和微量元素;刺槐林地的生物学性质和微量元素;小叶杨林地的物理和化学性质.(2)不同树种纯林土壤的极化趋势分别为:油松林地发生贫养化和微量元素亏损;落叶松林地发生微量元素富集但却贫养化;侧柏林地发生富C、N和生物学性质改善;华山松林地发生物理性质改善但却贫养化和生物学性质恶化;刺槐林地发生富养化、生物学性质改善但却微量元素亏损、物理性质恶化;小叶杨林地发生贫养化、微量元素亏损和物理、生物学性质恶化;白桦林地发生物理性质改善、微量元素富集但却贫养化;辽东栎林地发生微量元素富集.(3)相对林木抗极化能力,土壤的绝对综合极抗比属于中等以上(I ＞0.40)的性质分别为:小叶杨林地的物理性质; 侧柏林地的物理、化学性质和微量元素;落叶松、刺槐和白桦林地的所有性质.     

酸梨金属元素的分析

采用电感耦合等离子体发育光谱仪（ICP）对野生酸梨的金属元素进行了测试分析。结果表明：其常量元素中Ca的含量高达66.84%(mg/g),同时含有人体必需的微量元素Fe,Mn,V,Cu,Zn,Ni,Co等。及对人体有益的稀土元素Nd,Tm,Yb等。     

植物水分来源稳定氢氧同位素偏移研究进展

稳定氢氧同位素技术能有效计算植物根系水分吸收量,确定植物水分来源贡献,评估植物水分利用策略,是生态水文学探究大气-植被-土壤系统水分传输过程机制的有效工具。然而土壤与木质部水稳定氢氧同位素比值(δ²H和δ¹⁸O)偏移造成植物水分来源贡献率计算偏差,引起氢氧同位素结果差异的原因尚不明晰。该文首先简要介绍氢氧稳定同位素比值偏移现象,其次沿水分在土壤-植物-大气连续体中的传输路径构建梳理框架,系统阐述了3个界面(植物-大气界面、土壤-大气界面和根系-土壤界面)与2个空间(植物体和土壤层)中引起δ²H与δ¹⁸O偏移的自然效应,同时概述了土壤与木质部样品提取与测定技术中引起δ²H与δ¹⁸O偏差的人为效应。最后,根据现有研究进展提出主要问题,从获取同位素时空数据,微尺度同位素偏移原因,提取与测定技术的优化三方面指出未来的发展方向。     

提取方式对土壤和植物水分提取率的影响及其氢氧同位素分析

氢氧同位素示踪技术是研究土壤-作物-大气连续体(SPAC)水分循环的重要手段,而土壤水和作物水的提取方法是氢氧同位素研究最关键的一步。本文采用真空蒸馏和共沸蒸馏2种提取方法对不同含水量(35%、25%和15%)下的土壤(红粘土、红砂土和水稻土)和植物(橘树和水稻)茎叶的水分分别进行了提取,并对提取出的水分进行了氢氧稳定同位素的对比分析,旨在提出合适的提取方法。结果表明:真空蒸馏对土壤和植物水分提取率显著高于共沸蒸馏(P<0.001);土壤含水量和土壤类型对水分提取率影响不显著;而水稻水分提取率显著高于橘树(P<0.001),且叶的水分提取率显著高于茎(P<0.001)。真空蒸馏提取出土壤水分的δD和δ18O值与标准样的差异不显著,而共沸蒸馏下提取出土壤水分的δD与标准样差异显著(P<0.001),水稻叶和橘树叶的δD和δ18O值高于茎。研究表明,真空蒸馏比共沸蒸馏更适合土壤和植物水分的提取且其提取出的水分更能真实反映样品中氢氧同位素组成。     

大气O_3浓度升高对稻田土壤有效态微量元素的影响

利用中国稻/麦轮作系统O3-FACE(Ozone-Free Air Concentration Enrichment)试验平台,研究大气O3浓度升高(比周围大气高50%)对2009年稻季各生育期不同深度(0-5 cm,5-10 cm和10-15 cm)耕层土壤微量元素有效性的影响。结果表明,大气O3浓度增加对0-15 cm耕层土壤有效性-Fe、Mn、Cu、Zn的提高幅度分别为10.0%、8.1%、5.4%、40.3%,其中对Cu的提高幅度达显著水平;不同土壤有效态微量元素在土壤垂直分布规律不同,土壤有效态Fe、Zn含量随土壤深度增加而降低,土壤有效态Mn含量随深度增加而增加,而土壤有效态Cu含量在不同深度土层中基本稳定;大气O3浓度升高对土壤DTPA提取态Fe的提高幅度随土壤深度的增加而增大,而对土壤DTPA提取态Mn、Cu、Zn的提高幅度均随土壤深度的增加而降低;大气O3浓度升高对0-5cm、5-10cm处土壤DTPA-Cu和0-5cm处Mn含量增加幅度分别为13.2%、8.9%和30.2%,且分别达显著和极显著水平。文章指出大气O3浓度升高会对稻田生态系统土壤微量元素地球化学循环产生重要影响,应针对不同层次土壤有效态微量元素含量情况,从土壤性质和水稻生长两个方面进一步明确其影响机制。     

锌对两个品种茄子果实品质的效应

采用土壤盆栽试验和化学分析方法,研究缺锌土壤上增施锌肥对两种茄子(黑紫茄和竹丝茄)产量和品质的影响及品种间差异,为优质蔬菜生产中合理施用微量元素锌提供科学依据。结果表明:在缺锌土壤上种植茄子,施锌量在10-40mg/kg条件下对两个品种茄子均有显著增产效果,以锌肥用量为20mg/kg时增产效果最好,其中黑紫茄增产37.7%,竹丝茄增产82.5%;锌肥用量能够明显影响茄子品质,适当增加锌肥用量,果实中游离氨基酸、硝酸盐含量下降,而可溶性糖、维生素C、黄酮和芦丁及矿质元素锌、铁、钙含量升高。茄子果实中大部分品质成分的平均含量在施锌量为20 mg/kg达到最高,其次为40mg/kg和10 mg/kg。低锌土壤上增施适量锌肥(Zn 20mg/kg土壤)使两种茄子的品质明显改善,施锌过量(>40 mg/kg)茄果品质下降。     

不同施肥模式下土壤微量元素变化与转化特征

以长期定位试验为平台,研究不同施肥制度下土壤Fe、Mn、Zn、Cu、Pb含量的变化及转化情况。结果表明:施肥对土壤全量微量元素含量没有显著影响,但对元素有效态含量影响显著,施肥导致土壤有效态微量元素含量增加,具体表现为化肥配施循环猪圈肥(NPK+M)处理微量元素有效态最高,单施化肥(NPK)处理次之,循环猪圈肥(M)处理更低,对照(CK)处理最低。各处理土壤微量元素收入均小于支出,不同处理间收支差额NPK+M相似文献   

不测土条件下半定量施肥原理和模型评述

1　不测土条件下半定量推荐施肥的需求矿质营养学说是施肥最基本原理 ,它的诞生标志着人类主动施肥时期的开始。从早期的定性施肥阶段 ,发展到今天的定量施肥阶段 ,如何确定施肥量一直是施肥技术的核心和难点。测土是定量施肥或精确施肥的前提。然而 ,测土本身存在各种偏差或精度、测土需要费用 ,本文仅对代表性的不测土施肥模型及其原理进行评述。即使有了土壤有效养分的测定结果 ,如何将其转化为一季内土壤提供的养分量一直是个理论难题 ,特别是Ｎ素土壤供应量更为难测或难以估算。因此 ,如何在使用定量施肥模型的同时 ,而又将土壤养分因…     

Bioavailability index for quantitative evaluation of plant availability of extractable soil trace elements

A new index, Bioavailability Index (BI) and the corresponding experimental method were developed for quantitative evaluation of bioavailability of the extractable soil trace elements. Soils were first treated with various extractants (DTPA, HCl, NH₂OH·HCl+HCl) separately to remove the extractable elements. The soils after extraction were washed with deionised water to eliminate the extractant and its pH was adjusted with Ca0 and finally restored to its original pH level. Wheat (Triticum aestivum L.) and rape (Brassica chinensis) were planted in the untreated and treated soils for 8 weeks. The concentrations of the trace elements in plants were determined after harvest. Nutrient accumulation by plants is significantly reduced due to removal of extractable trace elements from the soil. BI of the extractable fraction was proportional to the ratio of plant accumulation reduction to trace element extractability. In the present study, BI value of the total content of soil trace elements was designated as 1. Though only a minor fraction of the total soil nutrient, generally less than 5%, was removed by DTPA, the nutrient accumulation by plants, especially for wheat, was reduced greatly, leading to relatively large BI values. For wheat, the average BI values of the eight nutrients Cu, Mn, Zn, Ni, Co, Pb, Cr, and V were found to be 22.7, 17.6 and 17.4 for the three testing soils, and for rape, the corresponding values of 8.9, 10.0 and 11.0 were obtained, indicating that the DTPA-extractable elements represent the highly available fraction of the total content. The BI values for HCl-extractable elements were much lower compared with those for DTPA. For wheat, the average BI values for the three soils are 2.0, 1.9 and 2.4, and for rape, the corresponding values are 4.8, 4.1 and 3.7. The high availability of DTPA-extractable trace elements and relatively low availability of HCl-extractable trace elements highlight the significant role that chelation action might play in plant nutrient acquisition. The different responses of wheat and rape to the soils previously subjected to the same extraction procedure could be explained by their genotypical differences in sensitivity to nutrient deficiencies. The quantitative nature of BI makes it valuable in the study of nutrient bioavailability and plant accumulation mechanisms.     

Trace elements in soils and crops.

To demonstrate the total amounts to be expected in soils, the ranges of contents of some 60 trace elements in ten representative Scottish arable surface soils are compared with ranges in soil-forming rocks and with crustal averages. It is, however, the amounts potentially available to plants rather than the total contents that are biologically significant. In temperate climates, trace element mobilization is greatest when weathering takes place under conditions of impeded pedological drainage, leading to the formation of gleyed soils. Mobilized trace elements occur in arable surface soils largely in adsorbed and chelated forms, which are available to plants to a greater or smaller extent depending on the prevailing soil parameters and on the element in question. Different species take up different amounts of trace elements: the proportions in the various plant parts vary with the element and the stage of growth. Information is required about the mobilization and uptake of many elements about which little is at present known but which may affect the functions of essential elements through inter-element interactions. Systematic soil surveys in which soils are mapped by associations related to parent material, with their series related to genetic soil types, provide a useful countrywide guide to trace element status.     

Identifying Metals Contamination in Soil: A Geochemical Approach

The geochemical evaluation methodology described in this paper is used to distinguish contaminated samples from those that contain only naturally occurring levels of inorganic constituents. Site-to-background comparisons of trace elements in soil based solely on statistical techniques are prone to high false positive indications. Trace element distributions in soil tend to span a wide range of concentrations and are highly right-skewed, approximating lognormal distributions, and background data sets are typically too small to capture this range. Geochemical correlations of trace versus major elements are predicated on the natural elemental associations in soil. Linear trends with positive slopes are expected for scatter plots of specific trace versus major elements in uncontaminated samples. Individual samples that may contain a component of contamination are identified by their positions off the trend formed by uncontaminated samples. In addition to pinpointing which samples may be contaminated, this technique provides mechanistic explanations for naturally elevated element concentrations, information that a purely statistical approach cannot provide. These geochemical evaluations have been successfully performed at numerous facilities across the United States. Removing naturally occurring constituents from consideration early in a site investigation reduces or eliminates unnecessary investigation and risk assessment, and focuses remediation efforts.     

不同施肥对退化稻田土壤肥力恢复的影响

为了探明不同施肥修复措施对退化水稻土壤肥力的修复作用,自2005年起采用盆栽试验连续3年对长期缺肥退化水稻土进行了土壤肥力培肥试验研究。结果表明:6种施肥修复措施均可以显著地改善退化水稻土的肥力特征,土壤有机质含量最多提高了14.0%,土壤有效磷显著增加,最高增加量达到39.0mg.kg-1,土壤速效钾均恢复到中等水平(80mg.kg-1)以上,但土壤碱解氮除水稻专用复合肥(ZY)处理基本维持试验前水平外,其他施肥措施均有所下降;不同施肥修复措施均可明显地提高土壤微生物数量、微生物活性以及微生物生物量C、N、P含量,但以有机无机肥配合效果最佳;有机无机肥配合还可以促进稻谷产量和显著提高肥料农学效率;对于长期不施肥导致的退化稻田土壤肥力的修复以在施用水稻专用复合肥的基础上配施有机肥的效果最佳。     

不同利用强度下绿洲农田土壤微量元素有效含量特征

以地处极端干旱背景下的塔里木盆地南缘策勒绿洲为研究区,以绿洲化为视角,根据当地农民耕作习惯于2005年选择4块试验农田,分别代表当地典型的农田利用强度。基于单项指数(Ei)和综合指数(Ec)相结合的评价方法,分析了绿洲农田在不同利用强度下的土壤Fe、Cu、Mn、Zn等微量元素有效性,探讨了土壤微量元素与人为耕作管理措施之间的关系。结果表明:人为耕作管理强度会对土壤微量元素有效含量产生重要影响,绿洲不同位置农田因施肥强度和管理方式的差别,其土壤微量元素有效含量特征存在显著差异。绿洲内部农田土壤有效Fe、Cu、Mn、Zn含量显著高于绿洲边缘各样地,新垦农田土壤有效Fe、Cu、Zn含量均低于对照样地;绿洲内部农田土壤微量元素有效性最高,新垦农田最低;农田土壤微量元素有效性与土壤有机质存在显著的正相关关系。     

Effects of nitrogen and water addition on trace element stoichiometry in five grassland species

A 9-year manipulative experiment with nitrogen (N) and water addition, simulating increasing N deposition and changing precipitation regime, was conducted to investigate the bioavailability of trace elements, iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in soil, and their uptake by plants under the two environmental change factors in a semi-arid grassland of Inner Mongolia. We measured concentrations of trace elements in soil and in foliage of five common herbaceous species including 3 forbs and 2 grasses. In addition, bioaccumulation factors (BAF, the ratio of the chemical concentration in the organism and the chemical concentration in the growth substrate) and foliar Fe:Mn ratio in each plant was calculated. Our results showed that soil available Fe, Mn and Cu concentrations increased under N addition and were negatively correlated with both soil pH and cation exchange capacity. Water addition partly counteracted the positive effects of N addition on available trace element concentrations in the soil. Foliar Mn, Cu and Zn concentrations increased but Fe concentration decreased with N addition, resulting in foliar elemental imbalances among Fe and other selected trace elements. Water addition alleviated the effect of N addition. Forbs are more likely to suffer from Mn toxicity and Fe deficiency than grass species, indicating more sensitivity to changing elemental bioavailability in soil. Our results suggested that soil acidification due to N deposition may accelerate trace element cycling and lead to elemental imbalance in soil–plant systems of semi-arid grasslands and these impacts of N deposition on semi-arid grasslands were affected by water addition. These findings indicate an important role for soil trace elements in maintaining ecosystem functions associated with atmospheric N deposition and changing precipitation regimes in the future.     

不同土壤类型蔗区甘蔗三高施肥优化研究

采用二次正交旋转组合设计 ,在砖红壤旱地蔗区和冲积土水田蔗区进行施肥优化试验 ,通过建立数学模型、模拟和寻优 ,初步建立了各类蔗区的优化施肥方案 .根据模型回归系数、单项性状指标的施肥方案和综合性状指标的优化施肥方案 ,对肥料三要素及其施用水平对蔗茎产量、蔗茎蔗糖分和净产值的影响进行了比较分析 .     

不同施肥制度下潮棕壤钾素肥力变化和土壤缺钾指标

通过在潮棕壤上进行的15年定位试验研究了不同施肥制度下钾素肥力变化和土壤缺钾指标.结果表明:不施钾肥处理加剧了土壤钾素的消耗,土壤速效钾和缓效钾浓度均有不同程度的下降;单施钾肥处理不能维持土壤钾素平衡,土壤中速效钾和缓效钾浓度仍有下降趋势;循环堆肥处理可在一定程度上补偿土壤钾的支出,但需配施钾肥;循环堆肥和钾肥配施处理土壤速效钾和缓效钾浓度基本保持不变.根据历年试验结果进行统计分析表明,用十字交叉法得出的玉米和大豆土壤速效钾临界值均为73mg.kg-1.