Speciation of Mercury in the Environment

Akagi, Hirokatsu; Nishimura, Hajime

doi:10.1007/978-1-4757-9071-9_3

Cited by 144 publications

(81 citation statements)

References 5 publications

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“…O emprego do NaCl faz com que o ditizonato de metilmercúrio formado na última etapa de extração em tolueno seja convertido em cloreto de metilmercúrio, logo após a sua passagem pelo topo da coluna cromatográfica. 25 As condições de operação do cromatógrafo a gás foram mantidas em: 150 °C para a coluna, 250 °C …”

Section: Instrumentalunclassified

“…As análises na água e biota consistiram em uma combinação de extrações com ditizona em tolueno, identificação e quantificação do metilmercúrio através da CG-DCE. 25 O excesso de ditizona da solução que contém o metilmercúrio foi retirado com auxílio de duas lavagens seguidas com 5 mL de 1 mol L -1 NaOH (Merck p.a.) e uma lavagem com 5 mL de água Milli Q e algumas gotas de 1 mol L -1 HCl.…”

Section: Procedimentos Analíticosunclassified

“…O extrato de ditizona em tolueno que contém o metilmercúrio foi submetido ao CG-DCE, onde o metilmercúrio foi identificado e quantificado. 25,26 Uma sub-amostra de tecido seco das amostras de biota aquática (50 mg), plâncton, mexilhão e peixe, foi digerida com uma solução alcoólica de 10 mL de 1 mol L -1 KOH (Merck p.a.) por aproximadamente 45 min a 100 ºC em banho-maria, empregando-se tubos de centrífuga Pirex Ò fechados com tampa de 50,0 mL.…”

Section: Procedimentos Analíticosunclassified

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Bioconcentração e biomagnificação de metilmercúrio na baía de Guanabara, Rio de Janeiro

Kehrig¹,

Malm²,

Palermo³

et al. 2011

Quím. Nova

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Recebido em 4/2/10; aceito em 7/10/10; publicado na web em 26/1/11 BIOCONCENTRATION AND BIOMAGNIFICATION OF METHYLMERCURY IN GUANABARA BAY, RIO DE JANEIRO.Methylmercury was determined in water and aquatic biota from Guanabara Bay. Trophic transfer of methylmercury was observed between trophic levels from prey (microplankton, mesoplankton and fish with different feeding habits) to top predator (pelagicdemersal fish). Top predator fish presented the highest methylmercury concentrations (320.3 ± 150.7 µg kg -1 dry wt.), whereas microplankton presented the lowest (8.9 ± 3.3 µg kg -1 dry wt.). The successive amplification of methylmercury concentrations and its bioconcentration factor with increasing trophic levels from base to top indicate that biomagnification may be occurring along the food web. Results suggest the importance of feeding habits and trophic level in the bioaccumulation of methylmercury by aquatic biota.Keywords: biotransference of methylmercury; water and organisms; trophic levels. INTRODUÇÃOExiste uma grande preocupação com relação ao aumento da poluição ambiental resultante do incremento do emprego intensivo e extensivo de produtos químicos, da liberação de substâncias potencialmente tóxicas, dos lançamentos de efluentes industriais e urbanos, bem como de seus efeitos para os ecossistemas e, consequentemente, para o homem. 1 Com o aumento das atividades industriais, agrícolas e mineradoras, bem como o crescimento populacional observados no último século, uma série de contaminantes (matéria orgânica, poluentes orgânicos e um grande número de compostos metálicos) vem sendo liberada para o meio ambiente, principalmente para a atmosfera e os ecossistemas aquáticos. 2 Os contaminantes de compostos metálicos presentes nos efluentes das atividades antrópicas apresentam pouca solubilidade na água resultando, então, em baixas concentrações, mesmo em locais próximos às suas emissões pontuais, via efluente. Entretanto, em ambientes estuarinos, os contaminantes metálicos estão preferencialmente associados ao material particulado em suspensão, que lhes serve de veículo para áreas mais distantes das suas fontes. 3 Dentre os diferentes metais que despertam interesse ambiental, presentes nos efluentes industriais e agrícolas e que, também, em diversas regiões apresentam concentrações naturais relativamente elevadas, encontra-se o mercúrio (Hg). A exposição ambiental ao Hg via cadeia alimentar, principalmente para consumidores de nível trófico superior, incluindo-se o homem, é significativamente maior, uma vez que este metal apresenta alta toxicidade e capacidade de sofrer biomagnificação ao longo das cadeias tróficas. 4 Este metal na sua forma orgânica mais tóxica, metilmercúrio (MeHg), é bioacumulado em até um milhão de vezes ao longo da cadeia trófica aquática, desde a sua base (microorganismos e plâncton) até os organismos de topo (peixes predadores e mamíferos) através de adsorção na superfície corporal e, principalmente, pela ingestão de alimento (peixes, crustáceos e cefalópodes). 5 O metilmercúrio é um age...

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Section: Instrumentalunclassified

Section: Procedimentos Analíticosunclassified

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Bioconcentração e biomagnificação de metilmercúrio na baía de Guanabara, Rio de Janeiro

Kehrig¹,

Malm²,

Palermo³

et al. 2011

Quím. Nova

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“…The Sansou Automatic mercury analyser Model Hg-3500 was used. The procedure for determination of total mercury (Akagi and Nishimura, 1991) was as follows: a known amount of sample was placed in a 50 ml volumetric flask, to which 2 ml of 1:1 nitric acid-perchloric acid solution and 5 ml of concentrated sulfuric acid were added, and heated on a hot plate at 230°C for 30 min. After cooling, the digested sam-* Below the surface of a core in cm .…”

Section: Methodsmentioning

confidence: 99%

Sedimentary environments based on textures of surface sediments and sedimentation rates in the South Yatsushiro Kai (Sea), southwest Kyushu, Japan

Rifardi

Oki

Tomiyasu

1998

Jour. Sed. Soc. Japan

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The main purpose of this study is to clarify the relation between characteristics of sediments and environmental conditions, based on the analysis of core samples from the South Yatsushiro Kai (Sea) which is located off the west coast of central Kyushu Island, Japan.Bottom sediment samples were collected at 74 stations in the southern part of the Yatsushiro Kai using gravity corers in March 1996. 62 core samples were used for the mechanical analysis by the settling-tube method, and Q-mode cluster analysis was carried out based on the proportion of grain size distribution (Wentworth size classes) . 61 core samples were available to estimate the sedimentation rates (during c. 50 years) which were recognized from the first appearance of high mercury contents of cores. On the other hand, the topmost one centimeter of 73 core samples, which is approximately 10 cc of wet sediments, was utilized for foraminifera) study.The general trend of the bottom current system in the area was discussed, based on the mechanical analysis data of bottom sediments, the distribution of sedimentation rates and the distributions of the number of individuals of planktic and living benthic foraminifera. Based on the results mentioned above, the South Yatsushiro Kai is subdivided into the following five areas:1) the area near the straits characterized by coarse sediments under the influence of strong tidal and bottom currents; 2) the southern part and the area off the mouth of the Minamata River, both of which are characterized by relatively coarse sediments under the influence of longshore currents and poorly sorted sediments supplied by the Komenotsu and Minamata Rivers; 3) the northwestern and eastern parts characterized by fine-grained sediments accumulated under conditions of rather stagnant water masses; 4) the central area, characterized by relatively fine sediments and a large number of planktic empty tests deposited on the sea bottom under the condition of rather weak tidal current systems; 5) the northern part characterized by gravels or gravelly sands which were derived from shallow coastal areas.Judging from the distribution pattern of the maximum mercury content at some horizons of each core, the fine-grained sediments polluted by mercury were transported northeastward and southward by weak longshore currents and spread toward north and west across the northern and southern parts of the South Yatsushiro Kai.

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“…This method is based on the fact that methylmercury dithizonate in the final solution in toluene is converted into its chloride form as soon as it passes through the NaCl on the top of the columns. 21 The column oven, detector and injector temperature were maintained at 150 °C, 250 °C and 180 °C, respectively. The carrier gas was nitrogen (99.999%) at a flow rate of 40 mL min -1 .…”

Section: Instrumentationmentioning

confidence: 99%

Methyl and total mercury found in two man-made Amazonian Reservoirs

Kehrig¹,

Palermo²,

Seixas³

et al. 2009

J. Braz. Chem. Soc.

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Metilmercúrio (MeHg) e mercúrio total (Hg) foram determinados em amostras de água e peixe coletadas em dois reservatórios da Amazônia Brasileira, que apresentam diferentes características limnológicas e ecológicas. As amostras de água de Tucuruí, reservatório mesotrófico com águas claras, apresentaram a concentração de Hg (12,7 ± 8,4 ng L ), an oligotrophic reservoir with black water. Neither Cichla spp. (piscivorous fish), nor Geophagus surinamensis (omnivorous fish) presented significant differences in length-normalized concentrations of MeHg and Hg in muscle, between both reservoirs. MeHg and Hg increased with body weight and standard length of Cichla spp., and also with the trophic level on the food chain. The Hg bioconcentration factor (BCF) increased with the trophic level of the fish, from the omnivorous (10 3 ) to piscivorous fish (10 4 ). Fish from Balbina, an ecosystem naturally rich in dissolved organic matter, presented the highest BCF. Not only the different limnological and ecological characteristics but also the feeding habits seem to influence the mercury concentration in fish.

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Speciation of Mercury in the Environment

Cited by 144 publications

References 5 publications

Bioconcentração e biomagnificação de metilmercúrio na baía de Guanabara, Rio de Janeiro

Bioconcentração e biomagnificação de metilmercúrio na baía de Guanabara, Rio de Janeiro

Sedimentary environments based on textures of surface sediments and sedimentation rates in the South Yatsushiro Kai (Sea), southwest Kyushu, Japan

Methyl and total mercury found in two man-made Amazonian Reservoirs

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