东北哈尼泥炭沼泽中酚酸的组成、酚铁相互作用及其环境意义

大量研究表明,溶解性有机质与铁的螯合对生物可利用性铁的输出有重要影响.然而,对于天然有机质,尤其是泥炭沼泽源的酚类物质,与铁相互作用的地球化学机制仍然缺乏研究.以长白山西麓哈尼泥炭沼泽为研究对象,调查了泥炭沼泽源水体可溶性总铁、亚铁、水溶性总酚等理化指标.同时,测定了泥炭中酚酸的组成及含量,分析对比泥炭与土壤中铁的主要赋存形态.并开展了酚铁相互作用模拟实验,研究了泥炭沼泽源水体中酚铁相互作用机制.结果表明:哈尼泥炭沼泽水体中亚铁浓度与水溶性总酚浓度显著相关,说明水溶性总酚对亚铁的存在及运移有重要影响.哈尼泥炭中含有原儿茶酸、咖啡酸、没食子酸、龙胆酸、丁香酸、阿魏酸、对羟基苯甲酸、对香豆酸、水杨酸、香草酸等多种酚酸.其中,具有儿茶酚或没食子酰基结构的原儿茶酸、咖啡酸和没食子酸能与亚铁形成稳定螯合物,是泥炭沼泽源水体中Fe(Ⅱ)保持稳定并可以远距离迁移的关键.研究还表明,原儿茶酸、咖啡酸、没食子酸和龙胆酸对Fe(Ⅲ)有显着的还原作用,有利于沼泽区水体中的保持较高Fe(Ⅲ)和Fe(Ⅱ)浓度.哈尼泥炭中铁主要以活动态(可交换态、络合态和无定形态)为主,为铁的迁移、转化和循环奠定了基础.鉴于泥炭沼泽在全球的分布面积巨大以及亚铁对海洋生物有促进作用,酚酸对铁的作用机制对陆地系统向海洋输送生物可利用铁具有重要意义,并对碳循环、硫循环以及气候变化有重要影响.      

全球变化背景下北方泥炭地释放溶解有机碳的驱动机制

泥炭地（peatland）是一类储碳效率很高的特殊陆地生态系统,其碳储量约占全球土壤碳库的近1／3,对全球碳循环有着举足轻重的作用。有证据表明在过去20余年,北半球大范围的天然水体中溶解有机碳的浓度呈显著增升趋势。普遍认为与全球变化背景下北方泥炭地大规模释放溶解有机碳有关,但其驱动机制尚不十分清楚。已经提出的具有代表性...     

离子吸附型稀土矿床中稀土的富集—分异特征:铁氧化物—黏土矿物复合体的约束

在离子吸附型稀土矿床中,黏土矿物被认为是离子吸附态稀土的主要吸附载体。风化壳中黏土矿物的透射电镜分析发现,黏土矿物普遍与铁氧化物形成复合体,很可能对稀土元素的富集–分异产生重要影响。本研究以广东省梅州市平远县仁居矿区的典型离子吸附型稀土矿床剖面为对象,通过提取富矿层中的细颗粒组分,采用X射线衍射、穆斯堡尔谱和透射电镜,对黏土矿物–铁氧化物复合体进行物相和形貌分析;在此基础上,采用顺序提取法测定不同化学形态的稀土总量,探究黏土矿物和铁氧化物对稀土元素富集–分异的贡献。结果表明,从全风化层到表土层,复合物从长石/伊利石–水铁矿/针铁矿复合体到高岭石/埃洛石–针铁矿/赤铁矿复合体,最终向高岭石–赤铁矿复合体转变。在表土层和全风化层的细颗粒组分中,离子交换态稀土约占25%和80%,而铁氧化物结合态稀土约占75%和20%。在表土层中, Ce的富集导致离子交换态和铁氧化物结合态稀土均富轻稀土。在全风化层中,随着深度的增加,离子交换态稀土由富轻稀土转变为富重稀土,铁氧化物结合态稀土均表现富重稀土的分异特征。离子交换态稀土总量和分异特征主要受黏土矿物–稀土界面作用和淋滤作用控制;而铁氧化物结合态稀土总...     

大九湖泥炭沼泽源铁有机配合物的络合稳定性及其生态环境意义

为了研究泥炭沼泽源铁有机配合物的络合稳定性,利用pH电位滴定法和荧光淬灭滴定法测定了大九湖泥炭沼泽中不同分子量段的DOM和Fe2+、Fe3+的络合稳定常数.pH电位滴定法结果（4.0~6.1）和荧光淬灭滴定法（1.5~4.1）差异较大,这与高pH条件下OH被脱质子化及Fe2+的氧化有关.相对而言,pH滴定法更适用于探究不同分子量段DOM与铁的络合稳定性,荧光淬灭法不改变样品酸碱条件,更适于研究不同价态铁与DOM的络合稳定性.研究结果表明:DOM与Fe3+的络合稳定常数大于Fe2+,低分子量段（< 3 kDa）的DOM与Fe2+、Fe3+的络合稳定常数更大.泥炭沼泽源铁有机配合物具有较好的络合稳定性,分子量相对较小的DOM与铁的络合能力更强.即便Fe2+氧化为Fe3+,仍能与DOM络合并保持较强的稳定性,这有利于陆源溶解性铁向水生态系统的输出.沼泽源铁有机配合物的络合稳定性还会影响铁的生物可利用性.      

北方泥炭沼泽中酚类物质释放的热敏感性研究:以英国威尔士地区雨养和矿养泥炭沼泽为例

利用高精度多梯度热培养系统,对英国威尔士地区两类典型的北方泥炭沼泽中酚类物质和溶解有机碳释放的热敏感性进行了为期1年的调查研究.研究结果表明,雨养泥炭沼泽(Bog)酚类物质释放的热敏感性Q10(总酚)月变化为0.92～1.57,而矿养泥炭沼泽(Fen)的月变化范围为0.93～1.30.酚类释放的热敏感性与土壤温度大致呈正相关关系.此外,土壤温度与溶解有机碳释放的热敏感性Q10(DOC)也呈正相关关系.总体上,雨养泥炭沼泽的热敏感性比矿养泥炭沼泽略高.除温度外,水文条件和植被等多种环境因子对酚类物质和溶解有机碳释放的热敏感性也有较大影响.研究结果还表明酚碳热敏感性比值Q10o(总酚)/Q10(DOC)相对稳定,土壤温度的变化对其影响有限.     

铁介导的土壤有机碳固持和矿化研究进展

铁作为有机碳矿物保护的核心元素之一,不仅对土壤有机碳库的结构及其稳定性有重要影响,其氧化还原动态变化也驱动着有机碳的周转过程。从铁介导的有机碳固持机制、铁结合态有机碳稳定程度的影响因素以及铁氧化还原过程驱动的有机碳矿化机制3个方面对铁—碳耦合关系进行了梳理分析。首先,铁介导的有机碳固持机制主要取决于自身的矿物学特性,能够通过吸附、络合、共沉淀和夹层复合等方式形成铁结合态有机碳,从而对有机碳起到直接的矿物保护作用。此外,铁氧化物还可以作为胶结剂促进团聚体形成,或通过改变环境pH进而间接保护有机碳。其次,铁结合态有机碳的稳定性主要受其自身性质（铁的矿物学特征、碳铁比、与有机碳的结合方式）、铁还原菌的种类以及小分子有机物的影响。第三,铁介导的有机碳矿化过程主要包括铁异化还原介导的有机碳矿化过程,以及由Fe（Ⅱ）化学氧化驱动的芬顿/类芬顿反应所生成的羟基自由基导致的非选择性有机碳矿化过程。但是,铁氧化物也能通过与外源输入碳复合形成铁结合态有机碳从而抑制土壤有机碳的矿化,以及通过降低酚氧化酶活性而减缓有机碳的矿化速率。因此,铁氧化物的矿物学特性和氧化还原敏感性对土壤有机碳的累积具有重要影响。最后...     

泥炭地碳源汇功能与“双碳”目标

自工业革命以来,大气中CO₂浓度快速升高导致了全球变暖,并引发了一系列气候和环境问题。应对气候变化、实现“碳达峰与碳中和”(以下简称“双碳”)已成为世界各国共同倡导的目标;而理解自然系统的碳源汇功能,对实现这一目标具有重要的意义。泥炭地是世界上分布最为广泛的湿地类型,对全球碳循环和气候变化有着十分重要的影响,其在实现“双碳”目标中的重要性受到越来越多的关注,这也使泥炭地碳循环研究成为前沿领域。本文简要回顾了国内外泥炭地碳循环的研究现状,阐述了泥炭地的碳源汇特征(包括CO₂净交换、 CH₄排放、溶解有机碳迁移、碳累积)、变化及驱动机制,并对其在实现“双碳”目标中的作用进行了分析。总体来说,泥炭地碳循环对全球碳源汇估算具有重要的影响,未来需进一步加强对泥炭地分布和碳库的研究,强化泥炭地生态环境演变规律、碳循环-相关过程对气候变化的敏感度以及研究薄弱地区等的针对性研究。在此基础上,科学地可持续管理和恢复退化泥炭地,如人为水文调节,以保持甚至增加其碳汇潜力和储存碳的稳定性,可发挥泥炭地在“双碳”时代的最大碳汇潜力,也将是减缓气候...     

铁锰氧化物对苯酚氧化降解的实验研究

为了考察铁锰氧化物对酚类污染物的氧化降解能力,采用天然以及合成的铁锰氧化物对苯酚的氧化降解进行对比实验研究。土壤中铁锰氧化物样品分别为天然针铁矿及氧化锰,合成铁锰氧化物样品分别为合成针铁矿及软锰矿。结果表明：苯酚与铁锰氧化物发生氧化还原作用时,还可能与土壤中杂质发生吸附等作用;铁锰氧化物还原反应强度随着反应介质pH值的升高而迅速下降;可用零级反应动力学方程拟合铁氧化物还原溶解反应,针铁矿溶解反应的强度与介质的pH值呈负相关关系;天然针铁矿对酚类污染物的氧化降解能力明显高于合成针铁矿,pH值对天然针铁矿溶解反应影响较大;可用一级指数衰减方程拟合锰氧化物还原溶解反应,锰氧化物溶解反应的强度与介质的pH值呈指数衰减关系;pH值对软锰矿还原溶解反应的影响大于对土壤中氧化锰的影响,pH值越小,影响越显著;对比pH值对铁和锰还原作用的影响发现,在pH=6.5时,锰氧化物仍有较强的氧化性能。     

神农架大九湖泥炭地藿类生物地球化学研究

<正>泥炭地尽管只占全球陆地面积的3%,有机碳的储量却高达全球土壤有机碳总量的30%,在全球陆地碳循环中起着重要的作用。因此,泥炭地关键带监测有着重要的科学意义。微生物活动是泥炭地关键带过程的主要营力之一。通过系统的环境条件-微生物活动-碳动态观测,可以帮助我们更好地认识泥炭地碳循环过程。藿类化合物是一类重要的细菌脂类标志物,在泥炭地中含量和种类丰富,可以用来指示泥炭地细     

河流碳通量与陆地侵蚀研究

河流碳通量系陆地侵蚀产物,它构成全球碳循环的一个重要环节。河流碳通量在数量上远小于全球碳循环的其他环节,但由于与陆地生态系统联系密切,故对它的研究尤为重要。全球每年河流碳通量约为1GtC（10⁹t碳）,其中约60％为无机碳、40％为有机碳。溶解态有机碳和颗粒状有机碳主要来源于土壤侵蚀,另有一部分有机碳来源于河湖中的浮游植物;溶解态无机碳主要源于大气中CO₂和碳酸盐;颗粒无机碳主要指未溶解的碳酸盐。亚洲季风区河流对全球河流碳通量具有较大贡献,而对其研究程度较低。河流碳通量研究既可为流域治理提供基础资料,也是进一步了解人为CO₂“未知汇”的途径之一。     

铁（氢）氧化物悬液中磷酸盐的吸附-解吸特性研究

铁（氢）氧化物对P的吸持和释放在一定程度上决定着P的生物有效性和水体富营养化。以两种环境中常见晶质铁氧化物（针铁矿和赤铁矿）为对照,采用X射线衍射（XRD）、透射电镜（TEM）、热重分析（TGA）和孔径分析以及动力学和吸附-解吸热力学平衡等技术方法,研究了弱晶质水铁矿对P吸附-解吸特性,并探讨了相关机制。实验表明,三种矿物对P的吸附分为起始的快速反应和随后的慢速反应,它们均符合准一级动力学过程,反应中OH释放明显滞后于P吸附,P吸附经历了从外围到内囤配位、单齿到多齿配位过渡的过程,与晶质氧化铁比,水铁矿吸附容量和OH释放量更大、慢速吸附反应更快、存在缓慢扩散反应阶段,吸附容量依次是：水铁矿（436μmol／m^2）〉针铁矿（262μmol／m^2）〉赤铁矿（228μmol／m^2）,针铁矿和赤铁矿吸附P符合L（Langmuir）模型,而水铁矿更符合F（Fremldlictl）模型。中性盐介质（KCl）中在最大吸附量时P的解吸率依次为：水铁矿（85％）〈针铁矿（10％）〈赤铁矿（125％）,柠檬酸通过配体解吸和诱导溶解两种机制促进P的解吸,最大吸附量时解吸率依次是：针铁矿（25％）〈水铁矿（32％）〈赤铁矿（50％）。     

Release of arsenic associated with the reduction and transformation of iron oxides

The behaviour of trace amounts of arsenate coprecipitated with ferrihydrite, lepidocrocite and goethite was studied during reductive dissolution and phase transformation of the iron oxides using [⁵⁵Fe]- and [⁷³As]-labelled iron oxides. The As/Fe molar ratio ranged from 0 to 0.005 for ferrihydrite and lepidocrocite and from 0 to 0.001 for goethite. For ferrihydrite and lepidocrocite, all the arsenate remained associated with the surface, whereas for goethite only 30% of the arsenate was desorbable. The rate of reductive dissolution in 10 mM ascorbic acid was unaffected by the presence of arsenate for any of the iron oxides and the arsenate was not reduced to arsenite by ascorbic acid. During reductive dissolution of the iron oxides, arsenate was released incongruently with Fe²⁺ for all the iron oxides. For ferrihydrite and goethite, the arsenate remained adsorbed to the surface and was not released until the surface area became too small to adsorb all the arsenate. In contrast, arsenate preferentially desorbs from the surface of lepidocrocite. During Fe²⁺ catalysed transformation of ferrihydrite and lepidocrocite, arsenate became bound more strongly to the product phases. X-ray diffractograms showed that ferrihydrite was transformed into lepidocrocite, goethite and magnetite whereas lepidocrocite either remained untransformed or was transformed into magnetite. The rate of recrystallization of ferrihydrite was not affected by the presence of arsenate. The results presented here imply that during reductive dissolution of iron oxides in natural sediments there will be no simple correlation between the release of arsenate and Fe²⁺. Recrystallization of the more reactive iron oxides into more crystalline phases, induced by the appearance of Fe²⁺ in anoxic aquifers, may be an important trapping mechanism for arsenic.     

Structural constraints of ferric (hydr)oxides on dissimilatory iron reduction and the fate of Fe(II)

Due to the strong reducing capacity of ferrous Fe, the fate of Fe(II) following dissimilatory iron reduction will have a profound bearing on biogeochemical cycles. We have previously observed the rapid and near complete conversion of 2-line ferrihydrite to goethite (minor phase) and magnetite (major phase) under advective flow in an organic carbon-rich artificial groundwater medium. Yet, in many mineralogically mature environments, well-ordered iron (hydr)oxide phases dominate and may therefore control the extent and rate of Fe(III) reduction. Accordingly, here we compare the reducing capacity and Fe(II) sequestration mechanisms of goethite and hematite to 2-line ferrihydrite under advective flow within a medium mimicking that of natural groundwater supplemented with organic carbon. Introduction of dissolved organic carbon upon flow initiation results in the onset of dissimilatory iron reduction of all three Fe phases (2-line ferrihydrite, goethite, and hematite). While the initial surface area normalized rates are similar (∼10⁻¹¹ mol Fe(II) m⁻² g⁻¹), the total amount of Fe(III) reduced over time along with the mechanisms and extent of Fe(II) sequestration differ among the three iron (hydr)oxide substrates. Following 16 d of reaction, the amount of Fe(III) reduced within the ferrihydrite, goethite, and hematite columns is 25, 5, and 1%, respectively. While 83% of the Fe(II) produced in the ferrihydrite system is retained within the solid-phase, merely 17% is retained within both the goethite and hematite columns. Magnetite precipitation is responsible for the majority of Fe(II) sequestration within ferrihydrite, yet magnetite was not detected in either the goethite or hematite systems. Instead, Fe(II) may be sequestered as localized spinel-like (magnetite) domains within surface hydrated layers (ca. 1 nm thick) on goethite and hematite or by electron delocalization within the bulk phase. The decreased solubility of goethite and hematite relative to ferrihydrite, resulting in lower Fe(III)_aq and bacterially-generated Fe(II)_aq concentrations, may hinder magnetite precipitation beyond mere surface reorganization into nanometer-sized, spinel-like domains. Nevertheless, following an initial, more rapid reduction period, the three Fe (hydr)oxides support similar aqueous ferrous iron concentrations, bacterial populations, and microbial Fe(III) reduction rates. A decline in microbial reduction rates and further Fe(II) retention in the solid-phase correlates with the initial degree of phase disorder (high energy sites). As such, sustained microbial reduction of 2-line ferrihydrite, goethite, and hematite appears to be controlled, in large part, by changes in surface reactivity (energy), which is influenced by microbial reduction and secondary Fe(II) sequestration processes regardless of structural order (crystallinity) and surface area.     

应用矿物磁测技术和X射线衍射研究氧化土中的磁性矿物

应用矿物磁测、Ｘ射线衍射和化学分析对氧化土的磁性矿物进行了研究。结果表明矿物磁测及磁分离技术与Ｘ射线衍射结合是鉴别土壤中磁性矿物的类型及其晶粒特征的有效方法,证明氧化土中的主要氧化铁矿物是赤铁矿和磁赤铁矿,针铁矿次之,磁铁矿偶见,其磁赤铁矿的含量可达１．６２％￣１．９２％。土壤中磁性矿物的晶粒特征多以超顺磁性和稳定单畴态存在,认为磁性矿物的成因是通过缓慢的成土化学作用产生的。     

几种铁（氢）氧化物对溶液中磷的吸附作用对比研究

铁(氢)氧化物不仅是土壤中广泛存在的矿物,也是重要的矿物资源。表生地质作用形成的针铁矿、赤铁矿和无定形氢氧化铁都具有纳米尺度,具有很高的表面积,表现出对磷的专性吸附,是低浓度磷的潜在吸附材料。本文通过铁(氢)氧化物对水溶液中磷酸根的等温吸附实验,初步对比研究了针铁矿、合成氧化铁黄、赤铁矿和无定形氢氧化铁对水中低浓度磷的吸附作用。结果表明,无定形氢氧化铁对水溶液中磷酸根的吸附能力最强(对低浓度磷的吸附达到5.5mg/g),其次是氧化铁黄和针铁矿,赤铁矿的吸附能力最差。几种铁(氢)氧化物对磷吸附容量的差别主要受比表面积控制。无定形氢氧化铁、合成氧化铁黄、针铁矿、赤铁矿对磷的吸附符合Freundlich等温方程。针铁矿和赤铁矿对磷的吸附动力学符合双常数速率方程。     

Secondary mineralization pathways induced by dissimilatory iron reduction of ferrihydrite under advective flow

Iron (hydr)oxides not only serve as potent sorbents and repositories for nutrients and contaminants but also provide a terminal electron acceptor for microbial respiration. The microbial reduction of Fe (hydr)oxides and the subsequent secondary solid-phase transformations will, therefore, have a profound influence on the biogeochemical cycling of Fe as well as associated metals. Here we elucidate the pathways and mechanisms of secondary mineralization during dissimilatory iron reduction by a common iron-reducing bacterium, Shewanella putrefaciens (strain CN32), of 2-line ferrihydrite under advective flow conditions. Secondary mineralization of ferrihydrite occurs via a coupled, biotic-abiotic pathway primarily resulting in the production of magnetite and goethite with minor amounts of green rust. Operating mineralization pathways are driven by competing abiotic reactions of bacterially generated ferrous iron with the ferrihydrite surface. Subsequent to the initial sorption of ferrous iron on ferrihydrite, goethite (via dissolution/reprecipitation) and/or magnetite (via solid-state conversion) precipitation ensues resulting in the spatial coupling of both goethite and magnetite with the ferrihydrite surface. The distribution of goethite and magnetite within the column is dictated, in large part, by flow-induced ferrous Fe profiles. While goethite precipitation occurs over a large Fe(II) concentration range, magnetite accumulation is only observed at concentrations exceeding 0.3 mmol/L (equivalent to 0.5 mmol Fe[II]/g ferrihydrite) following 16 d of reaction. Consequently, transport-regulated ferrous Fe profiles result in a progression of magnetite levels downgradient within the column. Declining microbial reduction over time results in lower Fe(II) concentrations and a subsequent shift in magnetite precipitation mechanisms from nucleation to crystal growth. While the initial precipitation rate of goethite exceeds that of magnetite, continued growth is inhibited by magnetite formation, potentially a result of lower Fe(III) activity. Conversely, the presence of lower initial Fe(II) concentrations followed by higher concentrations promotes goethite accumulation and inhibits magnetite precipitation even when Fe(II) concentrations later increase, thus revealing the importance of both the rate of Fe(II) generation and flow-induced Fe(II) profiles. As such, the operating secondary mineralization pathways following reductive dissolution of ferrihydrite at a given pH are governed principally by flow-regulated Fe(II) concentration, which drives mineral precipitation kinetics and selection of competing mineral pathways.     

Fast transformation of iron oxyhydroxides by the catalytic action of aqueous Fe(II)

Iron oxides may undergo structural transformations when entering an anoxic environment. These transformations were investigated using the isotopic exchange between aqueous Fe(II) and iron oxides in experiments with ⁵⁵Fe-labelled iron oxides. ⁵⁵Fe was incorporated congruently into a ferrihydrite, two lepidocrocites (#1 and #2), synthesised at 10°C and 25°C, respectively, a goethite and a hematite. The iron oxides were then submerged in Fe²⁺ solutions (0-1.0 mM) with a pH of 6.5. In the presence of aqueous Fe²⁺, an immediate and very rapid release of ⁵⁵Fe was observed from ferrihydrite, the two lepidocrocites and goethite, whereas in the absence of Fe²⁺ no release was observed. ⁵⁵Fe was not released from hematite, even at the higher Fe²⁺ concentration. The release rate is mainly controlled by characteristics of the iron oxides, whereas the concentration of Fe²⁺ only has minor influence. Ferrihydrite and 5-nm-sized lepidocrocite crystals attained complete isotopic equilibration with aqueous Fe(II) within days. Within this timeframe ferrihydrite transformed completely into new and more stable phases such as lepidocrocite and goethite. Lepidocrocite #2 and goethite, having larger particles, did not reach isotopic equilibrium within the timeframe of the experiment; however, the continuous slow release of ⁵⁵Fe suggests that isotopic equilibrium will ultimately be attained.Our results imply a recrystallization of solid Fe(III) phases induced by the catalytic action of aqueous Fe(II). Accordingly, iron oxides should properly be considered as dynamic phases that change composition when exposed to variable redox conditions. These results necessitate a reevaluation of current models for the release of trace metals under reducing conditions, the sequestration of heavy metals by iron oxides, and the significance of stable iron isotope signatures.     

Reduction of crystalline iron(III) oxyhydroxides using hydroquinone: Influence of phase and particle size

Iron oxides and oxyhydroxides are common and important materials in the environment, and they strongly impact the biogeochemical cycle of iron and other species at the Earth's surface. These materials commonly occur as nanoparticles in the 3–10 nm size range. This paper presents quantitative results demonstrating that iron oxide reactivity is particle size dependent. The rate and extent of the reductive dissolution of iron oxyhydroxide nanoparticles by hydroquinone in batch experiments were measured as a function of particle identity, particle loading, and hydroquinone concentration. Rates were normalized to surface areas determined by both transmission electron microscopy and Braunauer-Emmett-Teller surface. Results show that surface-area-normalized rates of reductive dissolution are fastest (by as much as 100 times) in experiments using six-line ferrihydrite versus goethite. Furthermore, the surface-area-normalized rates for 4 nm ferrihydrite nanoparticles are up to 20 times faster than the rates for 6 nm ferrihydrite nanoparticles, and the surface-area-normalized rates for 5 × 64 nm goethite nanoparticles are up to two times faster than the rates for 22 × 367 nm goethite nanoparticles.     

沉积物中铁氧化物的定量方法及其 在白垩纪大洋红层中的应用

赤铁矿和针铁矿是自然界中最稳定的两种铁氧化物,广泛存在于地球的各个圈层。很多沉积物的颜色都是由它们引 起的,它们的形成和保存具有重要的环境指示意义。实验室中赤铁矿和针铁矿的表征和鉴定手段很多,但受其含量低、结 晶差、颗粒细小难分离等因素的困扰以及某些测试方法自身的限制,能用于铁氧化物定量分析的方法很少。文中就常用的 基于X射线衍射（XRD） 和漫反射光谱（DRS） 的铁氧化物定量方法进行了系统评价。在定性分析的基础上,采用基于 XRD的K值法获得西藏床得剖面红色页岩中赤铁矿的含量为3.81％~8.11％,采用DRS与多元线性回归相结合的方法获得北 大西洋ODP1049C孔12X岩芯段棕色层中赤铁矿和针铁矿的含量分别为0.13％~0.82％和0.22%~0.81％,橙色层中赤铁矿和 针铁矿的含量分别为0.19%~0.46％和0.29%~0.67％。与其它分析结果的比较表明,这两种定量方法在白垩纪大洋红层中的 应用是可行的。但在实际应用时,首先要通过XRD和DRS相结合来提高定性分析的准确性,然后通过综合分析铁氧化物的 预判含量范围和结晶程度来选择合适的定量方法。