Properties of humic substances from the baltic sea and lake ermistu mud

Übner, Monika; Treuman, Maili; Viitak, Anu; Lopp, Margus

doi:10.1007/bf02990825

Cited by 19 publications

(3 citation statements)

References 12 publications

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“…However, phytoplankton is not the only, or possibly not even the major factor behind decreased Secchi depths . Some of the nonalgal matter increasing light attenuation in the water column, such as dissolved humic substances, may contain nutrients . This matter, while difficult or impossible to utilize by the phytoplankton, would show in the total nutrient concentrations.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Reaching the Targets of the Water Framework Directive in the Gulf of Finland

Fernandes

Kauppila

Uusitalo

et al. 2012

Environ. Sci. Technol.

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This paper describes the development of the EU Water Framework Directive central water quality elements from 1970 to 2010 in the Gulf of Finland, a eutrophied sub-basin of the Baltic Sea. The likelihood of accomplishing the management objectives simultaneously is assessed using Bayesian networks. The objectives of good ecological status in winter-time total nitrogen and phosphorus, summer-time chlorophyll-a and summer-time Secchi depth have not been met yet. In addition, the results indicate that it is unlikely for them to be achieved in the near future, despite the decreasing trend in nutrient concentrations over the past few years. It was demonstrated that neither phosphorus nor nitrogen alone controls summertime plankton growth. Reaching good ecological status in nutrients does not necessarily lead to good ecological status of chlorophyll-a, even though a dependency between the parameters does exist. In addition, secchi-depth status is strongly related to chlorophyll-a status in three of the four study-areas.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Reaching the Targets of the Water Framework Directive in the Gulf of Finland

Fernandes

Kauppila

Uusitalo

et al. 2012

Environ. Sci. Technol.

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“…Humic acids (HAs) produced in the aquatic environment differ in their properties from HAs produced in the soil. Compared with the latter, HAs are characterized by a lower carbon content and higher values of H:C , indicating that they are less aromatic. Also their spectroscopic properties are different, particularly regarding the visible light spectrum and ultraviolet radiation (UV–VIS).…”

Section: Introductionmentioning

confidence: 99%

Variation in the susceptibility of humic acids from the sediments of water reservoirs to oxidation

Cieślewicz

2013

Internat. Rev. Hydrobiol.

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The aim of this study was to determine whether, and to what extent, structures of pigment‐origin affect the susceptibility of humic acids (HAs) to oxidation, with the primary focus on derivatives of chlorophyll. The sediment samples were collected from lakes with different catchment management, and the Szczecin Lagoon, which is the estuary of the Odra River. HAs were extracted from sediments using 0.5 M NaOH solution. Sediments differed in their contents of total organic carbon (3.8–456.0 g kg−1) and total nitrogen (0.8–33.7 g kg−1). HAs extracted from sediments were characterized by the highly diverse composition of chemical elements and spectrometric properties regarding the visible‐light spectrum and ultraviolet radiation. HAs extracted from the sediments of lakes situated in the Chodzież and Wałcz Lake Districts (ChWLD) with forest catchment areas, were most susceptible to oxidation, indicating that the processes that occur during oxidation are affected by the content of pigment‐originated structures (the derivatives of chlorophyll) in the molecules of HAs. These structures are relatively resistant to oxidation, because they are present in the spectra of alkaline solutions of HAs after oxidation. The conducted studies also proved that the susceptibility of HAs of sediment origin to oxidation cannot be interpreted in the standard way applied to values obtained for soil HAs.

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“…In these works, it was verified that contact of the mud with the skin reduced the pain symptoms and also increased the potentiation of antioxidant defenses in patients (Bellometti et al 1997). As HAs are part of the mud composition (Ubner et al 2004), their permeation through the skin may have contributed to the effectiveness of these mud-pack treatments.…”

Section: Introductionmentioning

confidence: 90%

Produção e caracterização de nanopartículas de ácidos húmicos contendo Pluronic F127 para aplicações farmacêuticas

Alice Gomes de Melo

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Agradeço em primeiro lugar à Professora Maria Helena Andrade Santana pela orientação, incentivo, amizade e confiança ao longo deste trabalho.À Fernanda Lopes Motta pela co-orientação e auxílios que tanto contribuíram para este trabalho, e claro, pela grande amizade.Aos colegas do LDPB e principalmente ao Gilson, pela amizade e os cafés de todo dia.Às minhas companheiras de mestrado Amanda e Laise por tornar essa jornada ainda melhor. Ao Prof. Dr. Nelson Durán, do Instituto de Química, por ter disponibilizado o ZetaSizer Nano e auxiliado no uso do microscópio eletrônico de varredura (MEV). À Prof.ª Dr.ª Eneida de Paulo, do Instituto de Biologia, por ter disponibilizado o ZetaSizer Nano. À Profª Drª Melissa Gurgel Adeodato Vieira e à Drª Fernanda Martins participação na banca examinadora e pelas valiosas contribuições. Agradeço em especial minha mãe, irmãs, irmão e sobrinha pelo amor, apoio e incentivo, e ao Alex pelo amor, companheirismo e amizade. Por fim, agradeço ao CNPq pelo suporte financeiro. vi RESUMO Ácidos húmicos (AHs) são macromoléculas derivadas de substâncias húmicas (SH), provenientes da degradação da matéria orgânica. Eles podem conter diversos grupos funcionais em sua composição, como fenóis, ácidos carboxílicos e quinonas, sendo responsáveis por muitas de suas funcionalidades, por exemplo, pelo seu caráter antioxidante e fungicida. Devido ao caráter anfifílico e à desprotonação dos grupos, os AHs podem formar estruturas micelares em água, sendo úteis para aplicações farmacêuticas tanto independente quanto encapsulando fármacos hidrofóbicos e interagindo com tensoativos, oferecendo novas aplicações tecnológicas. Neste contexto, o objetivo deste trabalho foi a produção e a caracterização de nanopartículas de AHs contendo o tensoativo Pluronic F127 (PF127). O emprego do PF127 visou introduzir modificações estruturais nas micelas originais de AHs, possibilitando explorar as propriedades resultantes para aplicações farmacêuticas. Estudos de permeação em membranas sintéticas (poros de 30 nm) foram realizados visando caracterizar a elasticidade das partículas e simular sua permeação pelos poros da pele. A capacidade das partículas AH-PF127 de carrear fármacos hidrofóbicos foi estudada utilizando a curcumina. A atividade antioxidante dos AHs foi avaliada utilizando-se ensaios espectrofotométricos de sequestro dos radicais ABTS e DPPH. Além disso, foram realizados ensaios de atividade fungicida usando Candida albicans para AHs e AH-PF127. Os AHs comerciais foram caracterizados por análise elementar CNHS e quanto à composição de grupos fenólicos e carboxílicos pelas técnicas de RMN 13 C, EM-CG e FTIR, onde aproximadamente 30% do total de sua composição correspondeu a estes grupos. Quinonas não foram identificadas pelas técnicas, não sendo, portanto, observada atividade fungicida na amostra. As interações entre AHs e PF127 foram favorecidas por maiores razões molares AH:PF127 (1:8), resultando em nanopartículas esféricas, estáveis, de diâmetro médio e potencial zeta de aproximadamente 100 nm e -30 mV, respec...

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Properties of humic substances from the baltic sea and lake ermistu mud

Cited by 19 publications

References 12 publications

Evaluation of Reaching the Targets of the Water Framework Directive in the Gulf of Finland

Evaluation of Reaching the Targets of the Water Framework Directive in the Gulf of Finland

Variation in the susceptibility of humic acids from the sediments of water reservoirs to oxidation

Produção e caracterização de nanopartículas de ácidos húmicos contendo Pluronic F127 para aplicações farmacêuticas

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