Molecular iodine reduction by natural and model organic substances in seawater     

Victor W. Truesdale  George W. Luther III 《Aquatic Geochemistry》1995,1(1):89-104

The reactivity of 2 µM molecular iodine in seawater toward various organic compounds containing aromatic, -keto, amino, olefinic and sugar functional groups was investigated. More detailed studies have been made of the reduction kinetics with salicylic acid, -ketoglutaric acid and the polypeptide oxidized glutathione, particularly to establish whether variation over the pH range 4–9 would provide a similar reduction reactivity or fingerprint to that of molecular iodine added to natural seawater. The data indicates that compounds with only one functional group react with first order kinetics whereas compounds with multiple functional groups show more complex behaviour. Kinetic and thermodynamic modelling indicates that HOI is the main iodine species reacting with organic matter at seawater pH of 8.2. Based on the pH fingerprints, peptides and compounds containing carbonyl or -keto groups are the key reductants of molecular iodine added to seawater. These compounds form C-I and N-I bonds which can allow for a rich organic iodine chemistry in seawater. The model compound results are discussed in relation to oceanic processes.  相似文献   

Iron speciation and biogeochemistry in different nearshore waters     

M. ztürk  N. Bizsel 《Marine Chemistry》2003,83(3-4):145

Different environmental conditions in various nearshore waters dynamically determine the speciation of iron, its solubility, removal and hence bioavailability to phytoplankton. The iron speciation, the impact of phytoplankton blooms and the effects of organic matter on iron speciation and transformation were studied in four different coastal systems: the Trondheim Fjord, Norway, which is a coastal system that is open to a vast riverine impact; Hopevågen, Norway, a pristine coastal basin, which has negligible river and anthropogenic impact; zmir Bay, Turkey, a Mediterranean embayment with heavily polluted eutrophic inner–middle section, and the oligotrophic outer section. In this paper, we compare iron speciation in these different coastal systems. While colloidal iron (ColFe) was the predominant species especially in the Trondheim Fjord and to some degree also in Hopavågen, Chelex labile iron (ClxLFe) and hydrophobic organic-iron complex (HpOFe) were predominate species in both the inner–middle and the outer section of zmir Bay. The impact of phytoplankton blooms on the ClxLFe was significant especially in the Trondheim Fjord, in the inner–middle section of zmir Bay and in Hopevågen.  相似文献   

The effects of acid sulphate run-off on a subtidal estuarine macrobenthic community in the Richmond River, NSW, Australia   总被引：1，自引：0，他引：1  

Corfield  Jamie 《ICES Journal of Marine Science》2000,57(5):1517-1523

  相似文献   

水生生态系统中汞-硒相互作用研究进展   总被引：1，自引：1，他引：0  

南雪娇  余晓平  郭金玲  郭亚飞  邓天龙 《岩矿测试》2016,35(1):1-9

甲基汞是汞存在于水生生态系统(水体、沉积物和水生生物)毒性最强的形态,并通过食物链的传递对生物体产生危害,因此有效控制汞的甲基化过程是汞环境化学和毒理学研究的重要课题。生物体内硒对汞的甲基化过程有明显的抑制作用,明确汞和硒在水生生态系统的形态特征以及汞-硒相互作用机制,有助于解决汞污染问题。汞在生物体内的毒性与生物体内硒含量紧密相关,汞与硒相之间的相互作用主要表现在生成不溶的化合物促使汞去甲基化或受生物体内硒相关酶抑制被直接排除于生物体外,从而抑制了汞的毒害作用。本文评述了汞、硒在水生生态系统中的形态特征,指出在水体中合理添加硒化合物可抑制无机汞在生物体内甲基化过程,深入研究生物体内汞和硒相互作用机制及其生理效应是该领域未来发展方向。  相似文献   

福州市土壤硒形态分析及其迁移富集规律   总被引：12，自引：5，他引：7  

方金梅 《岩矿测试》2008,27(2):103-107

通过对福州市土壤和岩石中Se形态的分析研究结果表明,表层土壤中强有机态Se、腐殖酸结合态Se约占全量的57.44%,残渣态Se占28.77%,残渣态Se是土壤Se的重要储备库源,三者均与表层土壤Se全量呈极显著的线性正相关关系。表层土壤Se含量随土壤酸性的加强而增加,随有机质含量加大而增加的幅度较小;深层土壤Se受pH值的影响不明显,但受有机质含量的影响很大,两者线性回归关系达到极显著水平;不同岩石类型对土壤含Se量没有明显的影响规律,各介质中Se含量表层土壤>深层土壤>岩石,并且差幅巨大。这些研究结果揭示了在岩石风化、土壤发育(熟化)过程中有机质和黏土矿物吸附Se,致使Se较其他元素流失比例少,从而造成从深部到表层土壤Se相对富集的结果。同时,提出了利用全量来推导Se形态值的方法,建立了土壤Se全量与形态间的关系模型以及决定土壤有效态Se的公式,建议在评价土壤Se时只要考虑有机结合态Se、残渣态Se、离子交换态Se和全量Se。  相似文献   

Farmland mercury contamination in the vicinity of an organic chemical factory in Guizhou,China     

Junfang Zhang  Liya Qu  Xinbin Feng  Wei Zhang  Yanna Guo  Kai Lin  Mei Li 《中国地球化学学报》2008,27(4):424-430

This study assesses the level of contamination of Hg in farmland soils along the irrigating channel downstream from Guizhou Organic Chemical Factory （GOCF）, where metallic mercury is used as a catalyst to produce acetic acid. The total input of mercury into the environment, as announced by GOCF, is 140 t in the past 30 years （1971-2000）. Sampling sites were chosen based on the distance from the source of pollution--the chemical factory. A total of 39 samples were collected from the study area and analyzed for total mercury concentrations and methyl mercury concentrations. The characteristics of vertical and horizontal distributions of total mercury and methyl mercury in the study area （farmland） are described in this paper. Much attention was paid to the transformation of inorganic Hg into organic mercury species in soils as well. The results showed that the farmland has been heavily contaminated by Hg. Land cultivation activity, land utilization style and distance from the pollution source could be the dominant factors controlling the distribution of THg and MeHg. It is observed that active transformation of inorganic Hg into organic mercury species （MeHg） usually takes place in paddy soils.  相似文献   

A comparison between heavy metals released from soil and its efficient speciation extracted by sequential extraction procedure   总被引：2，自引：0，他引：2  

ZHANG Hui 《中国地球化学学报》2008,27(1):36-40

A simulating experiment was carried out on the interaction between natural precipitation and soil. The results demonstrated that the contents of heavy metals （V, Co, Cr, and Ni） released from soil into the solution under Earth＇s surface conditions are higher than the contents of those metals bonded to exchangeable species, which were extracted by sequential extraction procedure recommended by Tessier and others in 1979. It is demonstrated that the metals bonded to other 3 species （carbonate, Fe-Mn oxide, and organic matter） except those bonded to the exchangeable species in efficient speciation can be released under the Earth＇s surface conditions, when pH=4 in the reaction system, and the higher correlation coefficient indicated that the concentrations of heavy metals released from soil into the solution vary approximately with reaction time in terms of index regulations.  相似文献   

Distribution and speciation of mercury in the Hongfeng Reservoir,Guizhou Province,China     

HE Tianrong FENG Xinbin GUO Yanna QIU Guangle YAN Haiyu MENG Bo 《中国地球化学学报》2008,27(1):97-103

The water, pore water, sediment, and fish samples were collected from the Hongfeng Reservoir in November 2003 and February 2004 in accordance with trace metal protocols. The average concentrations of total mercury （THg）, dissolved mercury （DHg）, reactive mercury, dissolved gaseous mercury, total methylmercury, and dissolved methylmercury in the water columns were 8.00, 5.70, 0.63, 0.05, 0.16, and 0.07 ng/L, respectively. THg and DHg in the water columns, THg in pore water and THg in lake sediments of the Hongfeng Reservoir showed the level of mercury in the Hongfeng Reservoir was higher than in other natural waters in the world due to the loading of a lot of waste water with relatively high concentrations of mercury, whereas methylmercury concentrations in fish （wet weight） varied from 1.73-51.00 ng/g, much lower than in most remote lakes and reservoirs reported in northern Europe and North America. Methylmercury distributions in pore water and sediments showed methylation occurred mainly in the upper several centimeters of sediment cores in the Hongfeng Reservoir. The concentrations of dissolved organic carbon, total suspended particles, total Hg, and methylmercury were higher at Houwu than those at Daba in November 2003. It is suggested that other pollutants such as N and P from fishing farm and other waste water at Houwu, which resulted in deterioration of water quality, affected the concentrations and distributions of mercury species in the reservoir.  相似文献   

贵阳城市土壤重金属元素形态分析   总被引：6，自引：0，他引：6  

武永锋  刘丛强  涂成龙 《矿物学报》2008,28(2):177-180

选取贵阳市62个代表性的表层土壤样品,分析了其重金属元素的含量和存在形态.结果表明,贵阳城市土壤中5种重金属元素(Cr、Cu、Pb、Zn和Cd)的含量较高,且变化较大.表层土壤中Cr、Cu、Zn主要以残渣态形式存在,Pb主要以可氧化态形式存在.Cd可还原态含量高达47.5%,残渣态含量最低,说明Cd较活泼,具有潜在的环境影响能力.  相似文献   

Determination of Free Nickel Ion Concentrations Using the Ion Exchange Technique: Application to Aqueous Mining and Municipal Effluents     

Yamini Gopalapillai  Ismail I. Fasfous  John D. Murimboh  Tahir Yapici  Parthasarathi Chakraborty  Chuni L. Chakrabarti 《Aquatic Geochemistry》2008,14(2):99-116

Free metal ion concentration is generally considered a useful indicator of a metal’s bioavailability and ecotoxicity to aquatic biota. This article reports the speciation of nickel in mining and municipal effluents from Sudbury (Ontario, Canada), and also in model solutions containing a fully characterized laurentian fulvic acid (LFA) at environmentally relevant concentrations. A column ion exchange technique (IET) using a cation exchange resin (Dowex 50W-X8) was applied to determine free nickel ion concentrations. In model solutions, reasonable correlation was found between the predictions of an equilibrium-based computer speciation code, Windermere Humic Aqueous Model (WHAM) VI, and the results obtained by IET at low nickel-to-fulvic acid ratios. However at higher mole ratios, the WHAM VI predicted higher free nickel ion concentrations than IET. Only three out of six effluent samples showed reasonable agreement between the IET and the WHAM VI results, indicating the need for further development of IET for application to effluent waters.  相似文献