黄土高原不同封育年限草地土壤与植物根系的生态化学计量特征

黄土高原特别是干草原地区植被演替的研究比较薄弱。当前植物生态化学计量学的研究主要集中在植物叶片方面,对根系的研究较少。选取宁夏云雾山草原植被不同封育年限的土壤和植物样品,以生态化学计量学原理为基础,测定并分析了土壤与根系的碳(C)、氮(N)、磷(P)及其生态化学计量比与相互关系。结果表明:(1)随着封育年限的增加,土壤容重逐渐减小,土壤有机碳和全氮变异性较大,全磷变异性较小,且封育初期土壤有机碳和全氮含量先降后升,至封育20、30年,保持相对平稳。0~20 cm土层土壤的碳氮比(C∶N)、碳磷比(C∶P)、氮磷比(N∶P)分别为9.04~9.63、19.62~32.27、2.14~3.37,20~40 cm土层土壤的分别为8.68~9.22、15.74~26.32、1.80~3.03。土壤有机碳与全氮、全磷之间存在极显著的正相关。(2)植物根系C、N、P含量变化范围分别为357.6~381.4 g kg-1、7.35~8.18 g kg-1、0.54~0.70 g kg-1;根系中的C元素含量随封育年限的增加逐渐升高,N、P元素含量均小于全球平均值。根系C∶N随着封育年限的增加变异性较大,C∶P、N∶P随着封育年限的增加变异性较小。(3)植物根系的C∶N∶P化学计量特征受土壤的影响调控大于其自身,且土壤磷含量对植物根系C∶N∶P生态化学计量特征影响的显著性(p0.01)大于土壤氮含量(p0.05)。此外,该地区封禁后,草地生产力易受到土壤N含量的限制。     

三峡库区坡耕地典型香榧套种模式土壤碳氮磷及其生态化学计量特征

为阐明三峡库区坡耕地典型香榧套种模式对土壤碳(C)、氮(N)、磷(P)含量及其生态化学计量特征的影响,在重庆市云阳县宝坪镇香榧种植基地内,选取香榧纯林(TG)、香榧-黄精(TGP)、香榧-大豆(TGG)3种套种模式为研究对象,分析不同模式及土层深度下土壤C、N、P含量及其生态化学计量特征。结果表明：不同模式的土壤C含量无显著差异,N、P含量均表现为TGG(0.80,0.53 g/kg)>TGP(0.71,0.40 g/kg)>TG(0.56,0.39 g/kg),且与TG相比,TGG的N、P含量分别显著提高42.9%,35.9%。土壤C、N主要富集在0—10 cm土层,而P主要集中在10—20 cm土层。3种模式的土壤C∶N、C∶P、N∶P分别为8.39～10.73,31.63～45.22,3.25～5.61,均低于全国平均值(14.4,136.0,9.3)。N∶P<10,表明N为研究区限制性养分。相关性分析结果表明,土壤pH、容重和总孔隙度也是影响土壤C、N、P含量及其生态化学计量的重要指标。香榧套种模式有利于土壤养分的积累,TGG的C、N、P含量高于TGP和TG,...     

烤烟连作对土壤生态化学计量特征的影响

为阐明烤烟连作对土壤生态化学计量学特征的影响,采用野外调查与室内分析相结合的方法,对四川泸州烟区正茬和连作1、3、5年土壤的有机碳(SOC)、全氮(TN)、全磷(TP)和全钾(TK)含量及其化学计量特征进行了研究。结果表明:与正茬相比,烤烟连作1年对土壤养分含量无显著影响;连作至第3年时,SOC含量明显下降,而TP和TK含量显著上升;连作至第5年时,SOC含量显著下降了9.89%,TN、TP和TK则分别增加了14.37%、68.84%和27.58%。土壤C/N、C/P、N/P和N/K随连作年限的增加而降低,年均下降4.06%、9.25%、6.51%和2.36%。土壤SOC对C/N、C/P、N/P、N/K贡献为正,而TN、TP、TK对C/N、C/P、N/P贡献为负,土壤养分及其化学计量比的相关性受到各养分的共同影响。总体来看,烤烟在连作3年时即可引起土壤磷钾累积及有机碳降低,使其生态化学计量比发生变化,从而可能影响土壤养分间的平衡供应。     

宁南山区不同年限撂荒梯田土壤碳氮磷化学计量特征

为了探究不同年限撂荒梯田对土壤碳氮磷含量及其化学计量特征的影响,为宁南山区撂荒梯田的管理利用和植被恢复提供科学依据。选择宁南山区彭阳中庄示范区不同年限撂荒梯田(2,5,15,17,20 a)为研究对象,通过野外采样与室内测定相结合的方法,对研究区5个不同年限撂荒梯田0—60 cm土壤样品中的C,N,P元素含量及其化学计量比特征进行了分析。结果表明:在0—60 cm土层,不同年限撂荒梯田的土壤C,N分布规律一致,均随土层深度的增加而减小,表层0—10 cm出现了富集现象,且随着撂荒年限增加呈先降低后升高的趋势,其他4层呈波动式下降趋势,土壤全磷含量分布比较均匀。土壤C∶N随着不同撂荒年限的增加呈波动式升高趋势,撂荒20年0—40 cm土层土壤C∶N最高,并与其他各年呈显著性变化(p0.05)。土壤C∶P和N∶P均表现为在表层0—10 cm随着撂荒年限的增加,总体呈现出先降低后升高的趋势,其他各层总体呈现下降的趋势。土壤C∶P和N∶P随土层增加呈减小趋势。土壤C∶N与全N和土壤C含量相关性不显著。土壤C∶P与土壤C含量呈极显著的正相关,与全磷含量呈显著的正相关。土壤N∶P与土壤全N含量呈极显著的正相关,与全磷含量呈显著的正相关。通过上述分析,总体反映出撂荒梯田土壤碳氮磷及其化学计量比受到不同年限和土层深度的双重影响,农地弃耕撂荒演替对土壤肥力有一定程度的改善。     

太白山不同海拔土壤碳、氮、磷含量及生态化学计量特征

为探究太白山土壤碳(C)、氮(N)、磷(P)含量垂直分布特征,阐明土壤C、N、P生态化学计量学特征对海拔梯度的响应规律,在秦岭太白山1 700~3 500 m区域以100 m海拔间隔进行研究。结果表明:(1)不同海拔高度下土壤有机碳、全氮、全磷变化范围分别是23.56~83.59g kg-1、2.00~5.77 g kg-1、0.32~0.47 g kg-1。土壤有机碳与全氮含量随海拔梯度升高先增后降,土壤全磷含量空间变异较小;(2)土壤C∶N、C∶P、N∶P范围分别为7.17~18.41、60.61~190.4、5.81~12.26。随海拔增加,土壤C∶N在阔叶林带呈降低趋势,针叶林带时转变为增加趋势。土壤C∶P随海拔梯度的变化趋势与土壤C∶N类似,N∶P随海拔梯度增加先升后降,至3 200 m有所升高;(3)两个阔叶林带(辽东栎林带和桦木林带)与高山草甸的土壤C、N含量及生态化学计量比高。冷杉林带C、N含量及其生态化学计量比最小;(4)温度、含水量、海拔和植被对土壤C、N、P化学计量特征具有重要影响,通过冗余分析揭示每个因素分别可解释系统变异信息的25.0%、24.3%、11.1%和6.9%,合计为67.3%。可见这些环境因素直接决定了土壤养分及生态化学计量特征。结果可为探明森林土壤养分供应状况和限制因素及太白山生态系统的保护、森林土壤质量评价等提供基础。     

互花米草入侵对滨海湿地不同质地土壤碳氮磷及其生态化学计量比的影响

为了阐明外来物种入侵对滨海湿地不同质地土壤碳(C)、氮(N)、磷(P)及其生态化学计量比的影响，对福建省滨海地区东湖湿地两种质地土壤的土著种与入侵种植被下土壤C、N、P含量及其生态化学计量特征与影响因素进行了测定与分析。研究结果表明：相同植被下，壤质土的C、N、P及其计量比均高于砂质土。互花米草入侵增加了两种质地土壤的C、N含量及碳磷比(C/P)、氮磷比(N/P)，降低了土壤有效磷(AP)、P含量与碳氮比(C/N)，其中砂质土的土壤N含量显著增加了近1倍(P<0.05),AP含量下降近70%，壤质土的C/P增加了近2倍(P<0.05)。不同质地土壤中铵态氮(NH₄⁺-N)和硝态氮(NO₃^–-N)含量对互花米草入侵的响应不同，在壤质土中，互花米草入侵后降低了50%的NH₄⁺-N含量，增加了近3倍的NO₃^–-N含量(P<0.05)；而在砂质土中，互花米草入侵后土壤NH₄     

渭北旱塬不同年限撂荒地土壤酶活性及其化学计量变化特征

[目的]探究渭北旱塬区不同年限撂荒地的土壤养分、胞外酶活性及其化学计量的变化特征及影响因素，以期为渭北旱塬区撂荒地的改善与管理提供一定的理论依据。[方法]以渭北旱塬不同年限(5 a, 10 a, 20 a, 25 a和33 a)的撂荒地为研究对象，测定了土壤养分和参与土壤碳(C)、氮(N)和磷(P)循环的5种胞外酶活性，随后利用单因素方差分析、土壤胞外酶化学计量学模型和主坐标分析(PCoA)研究不同撂荒年限下土壤养分和胞外酶活性及其生态化学计量的变化规律及影响因子。[结果]随着撂荒年限的增加，土壤C和N获取酶活性显著减小，而P获取酶活性显著增加；土壤C、N和P含量变化与酶活性变化趋势相反。随撂荒年限延长，土壤微生物的C限制得到缓解，P限制逐渐加强。PCoA拟合环境因子分析结果显示：土壤可溶性有机碳(DOC)、总磷(TP)、速效氮(AN)和速效磷(AP)含量是驱动酶活性及其计量比变化的关键因子。[结论]撂荒对土壤养分状况具有显著改善作用，但随撂荒时间延长(20 a以上)会加剧微生物P限制，因此对经过长年撂荒的土地应当适量施用磷肥，以改善其土壤状况。     

黄土丘陵区生态治理对土壤碳氮磷及其化学计量特征的影响

为了探究不同生态治理措施对土壤碳(C)、氮(N)、磷(P)含量及其化学计量特征的影响,为黄土丘陵区的生态治理与植被恢复提供科学依据,以黄土丘陵区典型小流域王茂沟为例,通过野外采样与室内分析相结合的方法,对研究区坡耕地、林地、草地、灌木地及梯田等5个样地0—100cm土壤样品的C、N、P及其化学计量比进行了分析研究。结果表明:(1)坡耕地经过生态治理转变为林地、草地、灌木地及梯田等生态用地,土壤C、N含量分别提高了1.27,1.18,1.24,1.14倍及1.64,1.64,1.76,1.57倍;土壤C和N呈极显著的正相关关系;在0—100cm土层,林地、草地、灌木地及梯田的土壤C、N分布规律一致,均随土壤深度增加而减小,且在0—20cm土层出现了富集现象,而土壤P含量分布比较均匀;(2)坡耕地C∶N均值显著大于其他样地(P0.05),在0—20cm土层,土壤C∶P与N∶P表现为林地、草地、灌木地及梯田显著高于坡耕地(P0.05);土壤C∶N随着土层深度的变化不显著,C∶P与N∶P随土层加深呈减小的趋势;(3)土壤C、N、P化学计量比的分布主要由土壤C、N决定;土壤C∶P、N∶P与土壤中铵态氮、粘粒、砂粒、水稳性大团聚体含量之间的相关性均通过了显著性检验(P0.05)。土壤C、N、P及其化学计量比不仅受生态治理和土层深度的影响,还与土壤理化性质相关,土壤C∶N、C∶P、N∶P可以指示土壤的肥力状况。     

红壤区林地浅沟不同植被类型土壤生态化学计量特征

为了探究红壤区林地浅沟植被类型对土壤养分含量及其生态化学计量特征的影响,通过野外调查与室内分析相结合的方法,选取林下植被类型为草地和灌木地的浅沟为研究对象,以裸地浅沟为对照,对其表层(0—10 cm)土壤养分含量及生态化学计量特征进行了研究。结果表明:(1)浅沟土壤养分含量及其生态化学计量特征受植被类型和浅沟部位的共同影响。(2)与裸地浅沟相比,草地和灌木地浅沟的土壤养分含量显著增大(p0.05),草地土壤的C,N和P含量分别增加了67.7%,51.1%,200.0%,灌木地分别增加了84.6%,127.0%,226.3%;土壤生态化学计量特征则显著减小(除草地的C/N外),C/P和N/P分别减小了50.9%,46.8%和65.2%,51.1%。(3)在浅沟不同部位,泥沙沉积导致沟底土壤养分含量显著大于沟坡和沟缘,但生态化学计量特征没有明显的变化规律。(4)土壤C,N和P含量间呈极显著的正相关关系,N含量是C/N的主要限制因子,P含量是C/P和N/P主要限制因子。红壤区林地浅沟植被恢复后,虽然土壤养分含量显著增大,但整体水平仍然偏低,而N和P是该区植被恢复的限制性因素,在植被恢复过程中适当施用氮肥和磷肥,可加快植被恢复进程。     

不同放牧干扰对滇西北高原泥炭沼泽土壤生态化学计量特征的影响

为了阐明放牧过程对泥炭沼泽土壤化学计量特征的影响及机制,为放牧对湿地生态系统干扰及泥炭沼泽养分循环研究提供理论基础。以滇西北高原泥炭沼泽为研究对象,分析了土壤含水率、pH值、总有机碳(TOC)、总氮(TN)、总磷(TP)、铵态氮(NH~+_4-N)、硝态氮(NO~-_3-N)及土壤碳(C)、氮(N)、磷(P)生态化学计量特征,从而研究了放牧过程中藏猪翻拱(ZG)和牦牛践踏(JT)对泥炭沼泽土壤化学计量特征的影响。结果表明:放牧降低了土壤含水率、pH值、TN、TOC含量,增加了TP含量;ZG显著增加了NO~-_3-N含量。放牧降低了土壤养分化学计量,其中ZG和JT的C/P存在显著差异(p0.05);放牧降低了微生物生物量碳氮比(MBC/MBN)及微生物生物量碳磷比(MBC/MBP),却提高了微生物生物量氮磷比(MBN/MBP),其中ZG对微生物生态化学计量的影响显著高于JT;放牧增加了生态酶化学计量。冗余分析显示TP、含水率、容重、NO~-_3-N、TOC是主要影响化学计量的环境因子。MBC/MBN,MBN/MBP均与对应的生态酶化学计量呈正相关,然而MBC/MBP呈相反趋势。C/N,C/P均与对应的生态酶化学计量呈正相关,然而N/P与对应的生态酶活性呈负相关。土壤养分化学计量变化影响了微生物生态化学计量以及生态酶化学计量。     

Bioavailability of As,Cd, Co,Cr, Cu,Hg, Mo,Ni, Pb,Se, and Zn from Biosolids Amended Compost

Appropriate compost standards are being considered in Canada. Five aspects of compost safety and quality are being evaluated; probably the most controversial aspect is the standards for metals in compost. In order to assist in the development of appropriate standards, the authors began an extensive research project in October, 1993 to determine the bioavailability of metals from compost and compost-metal mixtures. Swiss chard was grown in compost-amended soils or compost in a growth room using five treatments of increasing percentages of compost in the media (0, 25 percent, 50 percent, 75 percent, 100 percent compost (v/v)). A Truro loamy sand and a race-track manure-biosolids compost (RTM-biosolids) supplemented with a high metal biosolids were used in a completely randomized design with five replicates. Dry matter yield, metal content in plant tissue, and total metal uptake were evaluated as well as the total and DTPA-extractable metal content in the compost-soil mixes. The results of this and five other experiments conducted by the authors will help determine whether the suggested limits for As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se and Zn in composts are appropriate.     

Variation of N,P, K,Ca, Mg,Mn, Zn,and al in slash pine foliage

Abstract

The seasonal patterns of foliage nutrient concentrations and contents were monitored for two growing seasons in an 11‐year—old Pinus el1iottii stand. In the first growing season after needle initiation, N, P, K, Mg, and Zn concentrations decreased, but this was followed by an increase in the fall and winter months. Another drop in concentration of all elements, except P, occurred in the second growing season. Decreases in total contents indicated that this drop was a result of translocation to other tissues. In contrast to the mobile elements, the concentration and fascicle contents of Ca, Mn, and Al increased with aging of the needles.

Between‐tree variability was least for N, P, and Zn and the N, K, Mg, Mn, and Zn in the current foliage had consistently lower variation than that in the 1‐year‐old foliage. Between‐tree variation for K was lower in the winter than the spring.

For pine foliage, recommended sampling period for N, P, Mg, and Zn is mid to late summer and for the other elements it is late fall to late winter.

There are several sources of variation that influence the level of nutrients in tree foliage. The most important of these, apart from the tree nutrient status, are seasonal fluctuations, variation between trees, and age of needles . Smaller sources of variation are associated with position of the needles within the crown, diurnal changes, year to year variation, and analytical errors^1,2. These variables must be studied in order to develop suitable sampling techniques and in Pinus this has been undertaken for P. banksiana ¹, P. taeda ³, P. strobus ⁴, P. resinosa ⁴, P. sylvestris ⁵, and P. radiata ^6,7. However, foliage sampling has not been studied in detail for slash pine (Pinus elliottii Englem var. elliottii) and earlier studies with other pines have been largely confined to temperate or cool climates.

This study reports the variation in elemental concentrations with season, age of foliage, and between slash pine trees growing in a subtropical climate in Florida.     

Phytotoxicity of cobalt,vanadium, titanium,silver, and chromium

Abstract

The phytotoxicity of five nonessential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Cobalt was one of the more mobile of the five trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10^‐5 M) and 142 (with 10^‐4 M) μg Co/g dry weight in leaves resulted in severe chlorosis. Vanadium as 10^‐4 M vanadate resulted in smaller plants but not in chlorosis. Leaf, stem, and root V, respectively, were 13, 8, and 881 μg/g dry weight. Titanium was somewhat mobile with considerable yield decrease at 10^‐4 M; leaf, stem, and root Ti concentrations, respectively, were 202, 48, and 2420 μg/g. Symptoms were chlorosis, necrotic spots on leaves, and stunting. Silver was very lethal at 10^‐4 M AgNO₃; at 10^‐5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem, and root concentrations of Ag for this treatment, respectively, were 5.8, 5.1, and 1760 μg/g dry weight. Plants grown with 10^‐5 N Cr₂O₇ were decreased in yield by about 25% with or without EDTA (ethylenediamine tetraacetic acid) while the same level of Cr₂(SO₄)₃ was essentially without effect. For the two salts, the leaf, stem, root concentrations for Cr, respectively were 2.2 and 1.3, 0.7 and 0. 7, and 140 and 104 μg/g. Most of the trace metals studied here had interactions in the uptake and/or distribution of other elements.     

Thin layer chromatographic determination of aflatoxins, ochratoxins, sterigmatocystin, zearalenone, citrinin, T-2 toxin, diacetoxyscirpenol, penicillic acid, patulin, and penitrem A.

A general method is described for determining 16 mycotoxins in mixed feeds and other food products used in the manufacture of these feedstuffs. The mycotoxins are extracted and cleaned up by extracting with solvents of different pH. Thin layer chromatography is used to separate the toxins; toxins are then quantitated by the limit detection method. The minimum detectable concentration of mycotoxins in various products is: aflatoxin B1 or G1, 4--5 micrograms/kg; ochratoxin A or ethyl ester A 140--145 micrograms/kg; citrinin 600--750 micrograms/kg; zearalenone, 410--500 micrograms/kg; sterigmatocystin, 140--145 micrograms/kg; diacetoxyscirpenol, 2400--2600 micrograms/kg; T-2 toxin, 800--950 micrograms/kg; patulin, 750--800 micrograms/kg; penitrem A 14,000--14,500 micrograms/kg; penicillic acid 3400--3650 micrograms/kg.     

Evaluation of Decomposition Procedure to Determine Ba,Co, Cr,Cu, Ni,Mn, V,and Zn Total Content in Soil Samples

Different procedures have been proposed to decompose soil samples. Most of them regard determination with fertility aims. In this case, the contents available to the plants are considered. On the other hand, there are procedures to determine total content. The objective of this work was to propose a new decomposition procedure to determine barium (Ba), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), vanadium (V), and zinc (Zn) total content in tropical soils with high content of oxides and silicate. According to the results, the digestion procedure proposed in this study provided satisfactory results for the contents recovery for the elements Ba, Co, Cr, Cu, Mn, Ni, V, and Zn, above 90%, and the use of inverted aqua regia, hydrogen peroxide (H₂O₂), hydrofluoric acid (HF), pre-digestions and agitation was shown as a new alternative for the high silicate content soil sample total digestion, such as the oxisols.     

Organochlorine pesticide residues in different Indian cereals, pulses, spices, vegetables, fruits, milk, butter, Deshi ghee, and edible oils.

A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items.     

Estimation of Reference Values for Cadmium,Cobalt, Chromium,Copper, Nickel,Lead, and Zinc in Brazilian Soils

Abstract

The objectives of this study were 1) to recommend reference values (RVs) and tolerance limits (TLs) for representative Brazilian soils and 2) to propose a model to calculate natural contents of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in a soil from the silt, clay, manganese (Mn), iron (Fe), and cation exchange capacity (CEC) values. A set of 256 soil samples was classified by similarity in seven groups, and the concentrations corresponding to the upper quarter of data collected were then calculated. These concentrations are proposed as RVs for Brazilian soils. Additionally, TLs were obtained for each group from the antilog expression (m+2s), where m=mean value and s=standard deviation of data transformed in log₁₀. The classification functions of discriminant analysis proved to be suitable to allocate new samples in the established groups. Thus, it is possible to evaluate soils under anthropic activity and, by comparison with reference values, to be aware of pollution risks in a given area.     

Caimans,Capybaras, otters,manatees, and man in amazonia

Amazonia, the world's largest tropical rain forest, is often assumed to be a virtually untouched wilderness. The region is often referred to as a demographic void; there is on average only about one person per sq. km. Yet in response to international market forces, the hand of man has penetrated deep into the imposing forests. Since colonial times, wildlife, particularly along rivers, has been exploited on a large-scale basis for commercial purposes. This paper focuses on the effects of the trade on some aquatic animals.     

Die Bindungsformen von Si,Mg, Fe,Al, Mn,Cr, Ni und Co in Saprolit und Laterit über Serpentinit,Insel Gebe,Indonesien

Fixation of Si, Mg, Fe, Al, Mn, Cr, Ni and Co in saprolite and laterite above serpentinite - Gebe Island, Indonesia The fixation of various major and trace elements has been studied in a saprolite/laterite profile above serpentinized peridotite. Sequential extraction of < 63 μm fraction shows different types of element fixation in soil: adsorption on mineral surfaces (1), fixation to Mn-oxides (2), bonding to poorly and better crystallized Fe-oxides (3). In the laterite, most of the extractable Si-, Al-, Cr- and Ni-contents are bound to goethitic Fe-hydroxide. The saprolite has considerable amounts of secondary quartz which has been formed during ageing of amorphous silica modifications. Their precipitation is favoured by high Si adsorption capacity of poorly crystallized Fe-hydroxide. In saprolite and laterite Co is bound to Mn-oxides. It can readily be extracted from pure Mn-oxides. In contrast, the intimate association of Mn-oxides to goethite reduces the rate of easily extractable Mn and Co in middle and upper zones of the laterite.