Transformation dynamics and reactivity of dissolved and colloidal iron in coastal waters     

Manabu Fujii  Hiroaki Ito  Andrew L. Rose  T. David Waite  Tatsuo Omura 《Marine Chemistry》2008,110(3-4):165-175

We have investigated the chemical forms, reactivities and transformation kinetics of Fe(III) species present in coastal water with ion exchange and filtration methods. To simulate coastal water system, a mixture of ferric iron and fulvic acid was added to filtered seawater and incubated for a minute to a week. At each incubation time, the seawater sample was acidified with hydrochloric acid and then applied to anion exchange resin (AER) to separate negatively charged species (such as fulvic acid, its complexes with iron and iron oxyhydroxide coated with fulvic acid) from positively charged inorganic ferric iron (Fe(III)′). By monitoring the acid-induced Fe(III)′ over an hour, it was found that iron complexed by fulvic acid dissociated rapidly to a large extent (86–92% at pH 2), whereas amorphous ferric oxyhydroxide particles associated with fulvic acid (AFO-L) dissociated very slowly with the first-order dissociation rate constants ranging from 6.1 × 10^− 5 for pH 3 to 2.7 × 10^− 4 s^− 1 for pH 2. Therefore, a brief acidification followed by the AER treatment (acidification/AER method) was likely to be able to determine fulvic acid complexes and thus differentiate the complexes from the AFO-L particles (the dissolution of AFO-L was insignificant during the brief acidification). The acidification/AER method coupled with a simple filtration technique suggested that the iron–fulvic acid complexes exist in both the < 0.02 μm and 0.02–0.45 μm size fractions in our coastal water system. The truly dissolved iron (< 0.02 μm) was relatively long-lived with a life-time of 14 days, probably due to the complexation by strong ligands. Such an acid-labile iron may be an important source of bioavailable iron in coastal environments, as a significant relationship between the chemical lability and bioavailability of iron has been well recognised.  相似文献   

P-immobilisation and phosphatase activities in lake sediment following treatment with nitrate and iron   总被引：3，自引：0，他引：3  

Gerlinde Wauer  Thomas Gonsiorczyk  Peter Casper  Rainer Koschel 《Limnologica》2005,35(1-2):102-108

The influence of a further developed inlake restoration method on the P-immobilisation and microbial activities, especially under anoxic conditions was investigated. The impact of nitrate and iron dosing with a newly developed nitrate storage compound (Depox^®Fe) was tested in enclosures in the eutrophic dimictic Lake Dagowsee, Germany. Additions of 50 g m⁻² of NO₃⁻–N and 66 g m⁻² of Fe³⁺ ensured availability of nitrate at the sediment surface during a 2-months period.As a result the phosphate release from the anoxic sediments was completely suppressed even 1 year after the application. The hypolimnetic deoxygenation was unaffected by the Depox^®Fe addition. However, sulfur reduction and methanogenesis were inhibited and the phosphatase activity increased.  相似文献   

大冶铁山地区河流水体及水系沉积物中重金属元素分布特征   总被引：7，自引：3，他引：7  

张晓军  胡明安 《地质科技情报》2006,25(2):89-92

矿产资源的长期勘探、开采和冶炼活动给大冶铁山地区的自然生态环境造成了严重破坏.对该区西港河、东港河河水和水系沉积物中重金属元素分布特征的研究结果表明,该区矿山开采和冶炼活动形成的重金属污染元素主要为Cd、As、Zn;其主要污染源为冶炼厂排放的废水,其次是采矿废弃物堆积渗漏水;重金属元素在河水与水系沉积物中的空间分布特征较相似,但水系沉积物中元素质量分数比河水中的普遍增高,元素变化的剧烈程度加剧.  相似文献   

大冶铁矿控矿构造研究及深部隐伏矿体定位预测   总被引：9，自引：2，他引：9  

刘玉成  杨艺华  王永基 《地质与勘探》2006,42(6):10-16

大冶铁矿主矿体分布于燕山期闪长岩与下三叠统大冶群大理岩和白云质大理岩接触断裂复合带,该接触带是大冶铁矿矿床的主要控矿构造.文章对矿区接触带控矿构造类型及其空间分布特征、接触带形态产状特征及其与成矿的关系、成矿定位机制等作了比较系统的阐述,预测矿区深部可新增铁矿资源量4000万t.  相似文献   

姑山采场东北帮边坡防渗透变形研究   总被引：1，自引：0，他引：1  

江思珉  朱国荣  程璐  高元宝  季月华 《高校地质学报》2006,12(2):281-284

通过分析姑山采场的水文地质和工程地质条件,探讨了利用粉细砂含水层和砂卵砾石含水层之间的粉质粘土层建造台阶式防渗帷幕的可能性,以消除姑山采场东北帮边坡因地下水和青山河水在边帮中可能对边坡造成渗透变形的隐患,为姑山采场安全开采东北帮优质铁矿石创造条件,也为姑山矿实施可持续发展提供技术支持。  相似文献   

Iron-water reaction at high pressure and temperature, and hydrogen transport into the core     

Eiji Ohtani  Naohisa Hirao  Tadashi Kondo  Masayoshi Ito  Takumi Kikegawa 《Physics and Chemistry of Minerals》2005,32(1):77-82

We observed a direct reaction of metallic iron with water to form iron hydride and iron oxide, 3Fe + H₂O–>2FeH_x + FeO, at pressures from 6 GPa to 84 GPa and temperatures above 1,000 K in diamond anvil cell (DAC). Iron hydride is dhcpFeH_x or -FeH_x, and iron oxide has the rhombohedral or B1 structure at pressures at least up to 37 GPa. The formation of an assembly composed of dhcpFeH_x and FeO with the B8 structure was observed at 84 GPa. In primordial Earth, water formed by dehydration of the low temperature primitive materials reacts with metallic iron in the high temperature component to form iron hydride FeH_x and iron oxide FeO. The former would be incorporated in the iron forming the core. Thus hydrogen could be an important element of the Earths core. This reaction would be essential for transport of hydrogen into the core in the accretion stage of the Earth.  相似文献   

云南会泽超大型铅锌矿床硫同位素和稀土元素地球化学研究   总被引：9，自引：0，他引：9  

李文博  黄智龙  陈进  许成  管涛  尹牡丹 《地质学报》2004,78(4):507-518

云南会泽超大型铅锌矿床规模大、品位富、伴生有用元素多 ,暗示其成矿环境较为特殊。本文分析该矿床原生矿体中矿石矿物的硫同位素组成和脉石矿物方解石的 REE含量 ,结合前人的碳、氢、氧、铅同位素分析资料和成矿年代测试结果 ,探讨矿床成矿流体的来源。矿床原生矿体中的硫化物均富集重硫 ,其δ34 S值集中于13‰～ 17‰之间 ,且有 δ34 S黄铁矿 >δ34 S闪锌矿 >δ34 S方铅矿 ,表明成矿流体的硫已达到平衡 ;硫化物的 δ34 S值与矿区和区域地层中膏盐层的δ34 S值相近 ,暗示成矿流体中的硫主要来自地层海相硫酸盐的还原 ,热化学还原是地层海相硫酸盐形成还原态硫的主要还原机制。矿区脉石矿物方解石的 REE含量相对高于本区各时代碳酸盐地层 ,低于非碳酸盐地层和峨眉山玄武岩 ,其 REE配分模式和有关 REE参数也与地层和峨眉山玄武岩存在明显差异 ;进一步分析结果显示 ,矿床成矿流体是一种壳 -幔混合流体 ,伴随峨眉山玄武岩岩浆活动过程中地幔流体 (包括地幔去气和岩浆去气形成的流体 )参与了矿床成矿流体的形成  相似文献   

老挝万象平原钾镁盐矿区开采技术条件研究     

任明忠 《云南地质》2004,23(2):179-187

万象平原丰富的钾镁盐矿产资源正有待开发，正确选择开采方式将能最大限度地保护环境和提高资源利用率。针对盐类固体矿产的两种开采方式——坑道开采(旱采)和水溶开采(水采)，分别从水文地质、工程地质和环境地质三个方面对矿床开采技术条件进行深入评价，研究确定了矿区的开采技术类型以及开采技术条件，并就旱采和水采条件分别进行对比分析，从中择优选取比较理想的水溶开采法——钻孔选择性溶浸法。  相似文献   

云南盈江六红厂银多金属矿床     

谢永富 《云南地质》2004,23(2):199-206

六红厂银多金属矿床系2002年国土资源大调查评价项目。综合研究该区基础地质、化探、地质普查成果，认为矿床形成与地层、构造、岩浆岩关系密切，对其资源潜力进行分析、预测、评价。  相似文献   

"元谋古陆"斑岩型金矿     

代清华  罗显辉 《云南地质》2004,23(3):310-320

元谋古陆是目前国内公认、具有找金前景的重要靶区之一。本文剖析元谋猛林沟金矿成矿地质条件、控矿因素和成因,对近600Km2范围内寻找中型 大型斑岩型金矿的可能性进行探讨。  相似文献