有机酸溶解砖红壤过程中Mn（Ⅱ）的释放规律

研究土壤Mn（Ⅱ）释放规律对揭示锰氧化物的形成机制和了解酸性土壤锰毒效应大小具有重要意义.结果表明,柠檬酸溶解砖红壤过程中,Mn（Ⅱ）的释放速率在前4 h比较迅速,其释放数量可达24 h反应时间内总释放量的59.5%,但随后释放速率逐渐减缓.快速阶段被认为是土壤表面交换态Mn（Ⅱ）的释放,而慢速阶段则与土壤锰氧化物的缓...     

锰氧化物对有机污染物的转化机制研究进展

以土壤/沉积物中普遍存在且具有较强氧化活性的锰氧化物为研究对象,探讨了水-锰氧化物体系对医药品和个人护理用品等典型环境污染物的转化行为,并从污染物的分子结构出发,分别综述了锰氧化物对酚类、胺类、氮杂环、氮杂环N-氧化物、酸类等典型环境污染物的分子转化机制.为该类污染物环境行为及其潜在风险的科学评价、有效控制奠定理论基础.     

锰生物氧化的研究进展及在水处理中的应用

自然界中锰氧化物的形成主要是通过微生物作用,而锰的微生物氧化机制较为复杂,除了多铜氧化酶、过氧化物酶外,最近发现微生物生成的超氧化物可能也参与了锰的氧化.微生物生成的生物锰氧化物具有较高的吸附氧化活性,其微观结构和活性会随时间快速变化.比如,锰的生物氧化初级产物具有强的诱导Mn(Ⅱ)氧化的活性,而次级产物则几乎没有.锰的生物氧化过程复杂而又广泛进行着,尤其在含锰水体的处理单元中发挥着重要的净水作用,为了深刻理解生物锰氧化物,对锰氧化细菌和真菌、锰生物氧化机理、生物锰氧化物的吸附氧化特征及潜在的工程应用等当前研究热点问题进行了综述.     

低分子量有机化合物对MnO_2和土壤氧化锰的还原溶解作用

为考察土壤锰氧化物的还原溶解行为,本文选取常见的根系分泌的8种有机酸(抗坏血酸、香草酸、柠檬酸、草酸、酒石酸、水杨酸、半胱氨酸和邻苯二甲酸)和1种酚类化合物(邻苯二酚),人工合成的Mn O2和5种富含氧化锰的土壤(广东徐闻的砖红壤、海南澄迈的砖红壤、云南昆明的砖红壤、浙江嵊县的红壤和江苏南京的黄棕壤),研究了有机化合物对氧化锰的还原溶解作用.结果表明,较低p H和较高温度有利于有机化合物对Mn O2的还原溶解.在p H 4.5—5.5和温度5—45℃范围内,不同有机化合物还原溶解Mn O2能力的大小顺序为:邻苯二酚半胱氨酸抗坏血酸香草酸柠檬酸草酸≈酒石酸水杨酸≈邻苯二甲酸.邻苯二酚、半胱氨酸和抗坏血酸对土壤中氧化锰也有较强的还原溶解能力.当5种土壤比较时,徐闻砖红壤中还原溶解出的锰量最高,其次为昆明砖红壤,嵊县红壤中还原溶解出的锰量最小.当有还原性有机化合物存在时徐闻砖红壤、昆明砖红壤和澄迈砖红壤中的氧化锰容易发生还原溶解反应,增加土壤中可溶态和交换态Mn2+的含量,并可能对植物产生锰毒害.     

锰氧化物-阳离子交换树脂复合材料的制备及其对水中重金属的吸附性能

采用原位沉淀-空气氧化法将锰氧化物负载于大孔强酸性阳离子交换树脂D001上,制备出一种新型锰氧化物-阳离子交换树脂复合材料Mn-D001,并对该材料吸附水中Pb2+、Cd2+、Cu2+的性能进行了深入研究.TEM、XRD以及XPS的分析结果表明,负载的锰氧化物以MnO2的形态存在.基于单一金属离子静态吸附的一元体系实验表明,Mn-D001比D001对Pb2+、Cd2+、Cu2+具有更高的吸附选择性,在高浓度竞争离子Ca2+、Mg2+、Na+共存的情况下,仍能保持较高的重金属去除率;Mn-D001对Pb2+、Cd2+、Cu2+的吸附行为符合准一级动力学模型(R2>0.99)和Langmuir吸附等温线模型(R2>0.99).在温度为303 K时,Mn-D001对3种重金属的饱和吸附容量可分别达到476.19 mg.g-1、243.90 mg.g-1及196.08 mg.g-1,优于原有树脂D001.基于复合重金属离子竞争吸附的二元、三元体系的实验表明,Mn-D001对3种重金属的吸附能力顺序为Pb2+>Cu2+>Cd2+,吸附能力由原有树脂D001以及负载的锰氧化物的性质共同决定.     

植物根表铁锰氧化物胶膜的环境生态作用

许多湿地、水生植物根系都具有向根际环境释放氧气和氧化物,在根表和根际形成铁、锰氧化物胶膜的能力。因其所具有的特殊的物理或化学结构,植物根表的铁锰氧化物胶膜在环境生态中起重要作用。文章综述了植物根表铁锰氧化物的形成与特征,对有害金属和类金属污染物、有机污染物的吸附和富集作用,对富营养化水体的净化作用,以及提高植物的耐酸和耐贫瘠能力。借助新技术或研究手段强化铁、锰氧化物胶膜对湿地或水体有害金属和有机污染物的调控作用,是今后的发展方向。     

粤东凤凰山茶区土壤锰、锌赋存形态特征及对茶叶的有效性

采用连续化学提取法对粤东凤凰山茶区12个茶园土壤Mn和Zn的5种赋存形态特征及对茶叶的有效性进行了研究。结果发现,茶区土壤Mn平均含量为337 mg.kg-1,Zn平均含量为166.0 mg.kg-1,Mn和Zn的形态分布规律均表现为残渣态>铁锰氧化物结合态>有机束缚态>可交换态>碳酸盐结合态。土壤铁锰氧化物结合态和碳酸盐结合态Mn含量以及碳酸盐结合态、有机束缚态和铁锰氧化物结合态Zn含量分别与土壤pH值呈显著正相关,可交换态Mn含量与土壤pH值呈显著负相关;有机束缚态Mn、Zn含量以及铁锰氧化物结合态Zn含量分别与土壤有机质含量呈显著正相关,而铁锰氧化物结合态Mn含量与土壤有机质含量呈显著负相关。茶区茶叶Mn平均含量为1 046.3 mg.kg-1,Zn平均含量为42.0 mg.kg-1。茶叶Zn含量分别与土壤可交换态、有机束缚态、碳酸盐结合态Zn含量以及有机质含量呈显著正相关;茶叶Mn含量分别与土壤可交换态、碳酸盐结合态、有机束缚态Mn含量呈显著正相关,而与土壤pH值呈显著负相关。土壤pH值和有机质含量对茶区土壤Mn和Zn的化学形态分布及茶叶中Mn和Zn的累积有重要影响。     

几种有机化合物对土壤中铁与锰的氧化物还原和溶解作用

应用我们提出的实验方法进行研究,结果表明,有机化合物的结构状况,还原强度和(或)络合强度是决定铁、锰溶解量的主要因素。铁的氧化物其还原溶解的次序是:无定形铁的氧化物>针铁矿>赤铁矿。某些铁、锰的氧化物表面的预处理将会引起铁、锰溶解量的降低。文中还提出了土壤中铁、锰的氧化物溶解的表面化学反应机制的初步设想。     

生物炭-锰氧化物复合材料对红壤吸附铜特性的影响

锰氧化物作为改性材料应用于制造复合材料一直是环境领域的研究热点,锰氧化物改性的复合材料在水处理、空气清新剂等领域应用广泛。但目前,将生物炭-锰氧化物复合材料作为吸附材料改变土壤对铜吸持能力的研究还不多见。采用等温平衡吸附法,测定生物炭-锰氧化物复合材料对红壤吸附铜的能力影响,并应用Freundlich方程Cs=KfCen分析红壤对铜的吸附特征。结果表明：不同用量的生物炭-锰氧化物复合材料加入后,均会明显提高红壤对铜的吸附量。添加0.5%、1.0%、2.0%和4.0%生物炭-锰氧化物复合材料的红壤处理,其铜的吸附量较未添加处理分别增加了63.1%、130%,310%和509%。Freundlich吸附方程能较好的描述不同用量生物炭-锰氧化物复合材料影响红壤对铜的吸附特征。添加0.5%、1.0%、2.0%和4.0%炭-锰材料处理的分配系数（Kf值）分别为0.176、0.286、0.653和0.800。生物炭-锰氧化物复合材料用量为4.0%时,分配系数（Kf值）较对照红壤提高了5倍,生物炭-锰氧化物复合材料加入红壤后对红壤pH值影响不大,对CEC（阳离子交换量）有较大的影响;生物炭-锰氧化物复合材料用量为4.0%时,CEC为5.59 cmol·kg-1,较对照增加了14.1%,温度升高,有利于提高红壤对铜的吸附能力。生物炭-锰氧化物复合材料加入红壤后,红壤在1034.63、537.22、471.45 cm-1处有吸收峰出现,红壤表面-OH、Mg-O、Si-O等活性官能团数量明显增加。生物炭-锰氧化物复合材料增加红壤对铜的吸附机制可能是红壤表面Mg-O、Si-O等官能团与铜形成了Mg-O-Cu-、Si-O-Cu-络合物,提高了红壤对铜的吸持能力。从土壤化学与土壤修复的角度出发,生物炭-锰氧化物复合材料可用于铜污染红壤修复。     

中国低硒带生态环境中硒的环境行为研究进展

本文综述了目前与低硒带硒生物地球化学循环有关的研究结果。从这些研究中可以看出,低硒带的形成主要由表层土壤对低硒母质层的继承性,演化趋势主要决定于降水输入和淋溶流失二个自然过程的相对通量及土壤对硒的保留程度,后者在很大程度上依赖于土壤铁锰氧化物含量,土壤中硒的挥发损失可能并不重要。土壤-植物系统中硒的小循环中,环境腐植酸物质对土壤硒的环境行为和生物有效性产生了显著影响。     

Chemical fractionation of metals in core sediments of Orogodo River,southern Nigeria

Sequential chemical extraction of metals (Cu, Ni, Mn, Fe, Pb, Cr, and Zn) from core sediments of the Orogodo River was carried out with a view of providing information on the phase distribution of these metals with respect to depths and seasons. The results indicate that copper was speciated into organic matter/sulfide, Fe–Mn oxides, and residual forms at 0–5?cm depth while at deeper sections copper was predominantly in the residual form. Nickel was speciated mainly into Fe–Mn oxides and residual forms. The average of lead in various particulate phases of the sediment are 0–100% for residual; 0–8% for carbonate; 0–16.2% for exchangeable; 0–10% for organic matter/sulfide form and 22–56% for Fe–Mn oxides bound metals. Manganese was speciated into exchangeable (10–36%) and Fe–Mn oxides bound (10–48%) at the surface layers of 0–20?cm depths and predominantly in the residual form in deeper sections implying partitioning into trioctahydral clay and/or well-defined crystalline oxides. Iron was predominantly in the Fe–Mn oxides and residual fractions, less than 8% in the organic fraction, and 24.4–37.3% in the exchangeable and carbonates fractions at the surface. The percentage contributions of iron in the exchangeable and carbonate fractions decreased to 3.2% at 55–60?cm depth. The amount of chromium in the exchangeable fraction ranged from 0% to 7% for exchangeable; 0–26.5% for organic matter/sulfide bound; 3.8–17.9% for Fe–Mn oxides; and 46.8–100% for residual fraction. The mobility factors of the metals indicated that these metals were relatively mobile at top sections as compared with deeper sections. The overall picture of metal mobility and availability indicates potential contamination risk by Fe, Zn, Mn, and Pb in the Orogodo River sediment system.     

选择性萃取方法在生物膜上铁、锰氧化物分离中的应用

1　IntroductionSurfacecoatings (biofilmsandassociatedminerals)existonallkindsofsolidphasesinnaturalaquaticenvironments.FeandMnoxideswerefoundedtobethemostimportantcomponentsofsur facecoatingsfortheirhighadsorptioncapacity[1—3].Tostudytherelativeroleofdif…     

Heavy metals availability (Fe, Mn, Zn, Cu and Cr) in Aden Gulf sediments under aerobic and anaerobic conditions

The present study aims to analyse the chemical speciation of heavy metals in relation to aerobic and anaerobic conditions. Two sediment samples (from the Gulf of Aden, Yemen) were incubated under flooded conditions. In particular, the chemical forms of Fe, Mn, Zn, Cu and Cr under the experimental conditions were studied using a sequential chemical extraction method. The pH and Eh of the suspension were measured as critical parameters controlling the fate of the metals in the environment. The results showed that the metals concentration in the different forms varied with time incubation and affected by the variation of redox potential and pH value. Also, the changes in both redox potential (Eh) and pH values had evident effects on heavy metals transformation. It is obvious that the highest redox potential affected the amount of iron and manganese in the oxides form. When the redox potential decreased to-133 and-170 mV, it caused a significant transformation of the Fe-Mn oxide form to the water-soluble and exchangeable fractions. Under anaerobic conditions, the relative percentage of all five metals including the summation of four fractions (the water-soluble and exchangeable, carbonate, oxides and organic fractions) constituted 45-60% of the total amount of iron, 33-50% for manganese, 33-63% for Zn, 63-74% for Cu and 19-43% for Cr. Both zinc and copper among water-soluble and exchangeable fraction were high at the end of incubation period, this accompanied by a significant decrease in the content of the organically bound fraction. In general, the reducing conditions were more favorable for metal bound to water soluble and exchangeable fraction.     

Modelling the potential mobility of Cd,Cu, Ni,Pb and Zn in Mollic Fluvisols

European floodplain soils are frequently contaminated with potentially toxic inorganic substances. We used a multi-surface model to estimate the aqueous concentrations of Cd, Cu, Ni, Pb and Zn in three Mollic Fluvisols from the Central Elbe River (Germany). The model considered complexation in solution and interactions with soil organic matter (SOM), a clay mineral and hydrous Al, Fe and Mn oxides. The amounts of reactive metals were derived from extraction with 0.43 M HNO₃. Modelling was carried out as a function of pH (soil pH ± 1.4) because it varies in floodplain soils owing to redox processes that consume or release protons. The fraction of reactive metals, which were dissolved according to the modelling, was predominantly <1%. Depending on soil properties, especially pH and contents of SOM and minerals of the clay fraction, the modelled concentrations partially exceeded the trigger values for the soil–groundwater pathway of the German soil legislation. This differentiation by soil properties was given for Ni, Pb and Zn. On the other hand, Cd was more mobile, i.e., the trigger values were mostly exceeded. Copper represented the opposite, as the modelling did not predict exceeding the trigger values in any horizon. Except for Pb and partially Zn (where oxides were more important), SOM was the most important adsorbent for metals. However, given the special composition and dynamics of SOM in mollic horizons, we suggest further quantitative and qualitative investigations on SOM and on its interaction with metals to improve the prediction of contaminant dynamics.     

Geochemical index of trace metals in the surficial sediments from the western continental shelf of India, Arabian Sea

The present study focuses on the determination and abundance of trace metals (viz. Cu, Ni, Zn, Cr, Co, Cd, Mn and Fe) in the surficial sediments of west coast of Arabian Sea along the Indian subcontinent. Sediment samples were collected from three transects along the western continental shelf of Arabian Sea. The enrichment of Fe and Mn in coastal oxic-sediments indicates the precipitation of these redox sensitive elements as Fe- and Mn-hydroxides and oxides, whereas the low Fe and Mn concentrations in the oxygen deficient sediments of deeper stations reflects the dissolution of their hydroxides and oxides. Concentrations of fairly redox insensitive trace metals like Cu, Ni, Zn, Cr and Cd (with the exceptions of Cr) showed higher values at nearshore sediments, then it decreased towards seaward and again showed a slight increase at oxygen minimum stations in all the three transects. This geochemical variability in their distributional characteristics is mainly associated with the extent to which the precipitation or dissolution of Fe- and Mn-oxides/hydroxides occur since the scavenging or releasing effects of Fe- and Mn-oxides/hydroxides act as significant ‘sinks’ or ‘sources’ of heavy metals. The change in wind pattern, coastal upwelling and increased productivity are also the reported factors which influence the biogeochemical cycling of trace metals in the surface sediments of west coast of India. Enrichment factor generally showed a high gradient accumulation from nearshore to shelf.     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...     

Speciation of heavy metals in suspended particulates in urban air†

An anayltical procedure based on a sequential extraction scheme is applied to samples of suspended particulates from an urban area of Barcelona. This area presents high levels of air pollution owing to automotive emissions and industrial activity.

The procedure allows the partitioning of particulate trace metals into four fractions: soluble and exchangeable, bound to carbonates and iron‐manganese oxides, bound to organic matter and residual. In this work, the chemical associations of Fe, Pb, Cu, Mn, Cr and Cd have been investigated.

In the analysed samples, only the cadmium is predominantly in the first fraction whereas the other metals are largely associated to carbonates and Fe‐Mn oxides.     

广州城市水体沉积物中重金属形态分布研究

选取广州城市水体中的４ 个污染沉积物样品,采用连续提取法研究沉积物中重金属元素（ Ｐｂ 、 Ｚｎ 、 Ｃｕ 、 Ｎｉ 、 Ｃｒ 、 Ｍｎ） 的形态分布,结果表明：重金属元素主要以残渣态、有机结合态和氧化铁结合态存在,其中 Ｐｂ 、 Ｎｉ、 Ｍｎ 以残渣态和氧化铁结合为主, Ｚｎ 以残渣态和有机结合态为主, Ｃｕ 以有机态和氧化铁结合态为主, Ｃｒ 以氧化铁结合态为主。沉积物中固相组分对重金属的富集能力为：无定型氧化锰＞ ＞ 碳酸盐＞ 氧化铁＞ 有机质,而富集量则是后两者大于前两者。     

Annual production and molecular weight as an influential factor for environmental distribution of chemicals — a case study in Japan

The changes promoted by treatment of a highly polluted soil with sulphuric acid or calcium hydroxide for changing its pH value are studied by controlling physical properties (particle size, TGA and DTA curves), evolution of metal species (exchangeable, as carbonates, related to Fe‐Mn oxides, linked to organic matter and residual) and metal uptake by plant cultures. Metal contents were determined, after wet digestion with HF—HNO₃—HC1O₄ when necessary, by AAS (Ca, Mg, Cu, Pb, Mn, Fe, Zn) or emission (Na, K). The treatment of soil with successive amounts of sulphuric leads to changes in particle size, hydration properties and exothermic peak for organic matter combustion. Very small changes were, however, detected in the alkaline treatment of soil. Soil treatments do not have practical influence on speciation of some metals (Na, K, Mg, Pb, Mn, Fe), but the intensity of the acid treatment leads to both an increase in the Cu extraction and a decrease in the Ca solubilization, probably through gypsum formation. In the case of zinc a maximum solubility in the middle of the range of acid treatment was observed. The comparison among extractants shows solubilities high for two pollutants (Pb, Cu), associated mainly to Fe—Mn oxides and organic matter, and low for two macrocomponents (Fe, K). The rest of metals, basically present in soil as carbonates or oxides, have intermediate extractions. Pot cultures weights depended mainly on both the treatment of soil (poor development in the more acid sample and drainage difficulties in the rest of acid treatments) and the situation (very low weights in laboratory runs as compared with outside), but the irrigation with water or a diluted sulphuric acid solution (at pH = 4.0) did not produce significant weight changes. Tendencies to increase plant pollution were observed for smaller soil pH, acid irrigation and probably for outside cultures, due to uptake by leaves.     

Sequestration of heavy metals from soil with Fe–Mn concretions and nodules

In recent years, heavy metal contamination has become a major environmental issue in many parts of the world. Fe and Mn oxides, oxyhydroxides and hydroxides have long been recognized as scavengers playing an important role in controlling the location, mobility and bioavailability of metal contaminants in soils. Fe–Mn concretions and nodules are discrete bodies made of soil or sediment materials cemented together under the influence of Fe and Mn oxides. Here metals sorption by Fe–Mn concretions and nodules are surveyed and critical reviewed. Valuable available literature data demonstrate that the formation of Fe–Mn concretions and nodules is the most efficient and durable process for metal contaminants sequestration in the soils. The papers discussed in this review show that the application of Fe–Mn concretions and nodules, as geochemical scavengers for remediating metal contaminated soils, is strongly recommended.