Chemical and biological studies on environmental humic acids

Yonebayashi, Koyo; Hattori, T.

doi:10.1080/00380768.1988.10416472

Cited by 89 publications

(22 citation statements)

References 8 publications

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“…The concentrations of metals used in field experiments were those previously tested in laboratory in the experiments to assess the complexation capacity of same AHS. A total of 40 samples containing AHS with 5.0 mg L -1 of DOC received known concentrations of each metal, being 0.4, 1.6 and 5.9 mg L -1 for Al 3+ , 5.9, 13.7 and 43.7 mg L -1 for Cr 3+ , 5.9 and 43.7 mg L -1 for CrO 4 2-and 0.5, 17.7 and 377.4 mg L -1 for Ni 2+ . All these samples were kept in laboratory and field conditions under light and dark conditions.…”

Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

“…(1) Solar radiation effect on the complexation capacity of AHS The effect of solar radiation on the complexation capacity of Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ metals was assessed with microcosm experiments. These experiments were made by exposing samples containing 5.0 mg DOC L -1 AHS and different concentrations of metals as a strategy to maintain the same conditions of temperature and solar radiation intensity that occurs in the aquatic body.…”

Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

“…Complexation capacity studies were made individually with Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ metal ions. The metal solutions were prepared using reagents from pure analytical grade (AlCl 3 .6H 2 O, NiCl 2 .6H 2 O and K 2 CrO 4 from Synth, Diadema, Brazil; CrCl 3 .6H 2 O, from Sigma/Aldrich) in ultrapure water (Millipore, Direct-Q, France).…”

Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

“…The Stern-Volmer model allows the calculation of K C from experiments where the metals are being gradually added to the AHS and the fluorescence signal is begin followed after each addition. Due to the aforementioned, the goal of this work is to evaluate the effect of solar radiation in the complexation capacity of AHS with metals species, such as Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ .…”

Section: Introductionmentioning

confidence: 99%

“…1,2 They can participate in the complexation reactions with metal ions thereby influencing the transport and availability of them in the environment, 2-4 may suffer interactions with organic compounds and thus, reduce or increase its toxicity to the biota, 4,5 can act in redox 6 and photochemical reactions. 7 Aquatic HS are products of the decomposition of vegetal and animal remains from microbiological transformations.…”

Section: Introductionmentioning

confidence: 99%

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Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo

Toffoli

Moreira

et al. 2012

J. Braz. Chem. Soc.

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Este estudo teve como principal objetivo avaliar o efeito da radiação solar sobre a capacidade de complexação das substâncias húmicas aquáticas (AHS) com as espécies metálicas Al 3+ , Cr 3+ , CrO 42-e Ni 2+ . Microcosmos foram montados com AHS extraídas do Rio Preto com concentração de 5,0 mg L -1 de carbono orgânico dissolvido e diferentes concentrações de metais, sendo expostos à radiação solar in situ. As constantes de estabilidade condicional foram de 2,0 × 10 -2 , 1,1 × 10 -5 e 2,6 × 10 -2 para os complexos AHS-Cr 3+ , AHS-Ni 2+ e AHS-CrO 4 2-, respectivamente. Os resultados mostraram que a radiação solar foi responsável por um decréscimo na capacidade de complexação de 15-26% para AHS-Al 3+ , 15-72% para AHS-Cr 3+ , 12-18% para AHS-CrO 4 2-e de 13-42% para AHS-Ni 2+ . Conclui-se que a radiação solar altera a disponibilidade de metais previamente complexados às AHS, tornando-os disponíveis no corpo aquático.This study had as main objective to assess the effect of solar radiation on the capacity of the aquatic humic substances (AHS) to complex Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ . Microcosms were prepared with AHS from Preto River containing 5.0 mg L -1 of dissolved organic carbon and different concentrations of metal species, being exposed to solar radiation, in situ. Conditional stability constants obtained for the AHS-Cr 3+ , AHS-Ni 2+ and AHS-CrO 4 2-complexes were 2.0 × 10 -2 , 1.1 × 10 -5 and 2.6 × 10 -2 , respectively. The results showed that solar radiation is responsible for decreasing capacity complexation in 15-26% for AHS-Al 3+ , 15-72% for AHS-Cr 3+ , 12-18% for AHS-CrO 4 2-and 13-42% for AHS-Ni 2+ . We can conclude that solar radiation alters metals' availability previously complexed to AHS, making them available in the aquatic body.Keywords: aquatic humic substances, metal complexation, solar radiation, fluorescence IntroductionAquatic humic substances (AHS) have been intensively studied because they play an essential role in biogeochemical processes. 1,2 They can participate in the complexation reactions with metal ions thereby influencing the transport and availability of them in the environment, 2-4 may suffer interactions with organic compounds and thus, reduce or increase its toxicity to the biota, 4,5 can act in redox 6 and photochemical reactions. 7 Aquatic HS are products of the decomposition of vegetal and animal remains from microbiological transformations. They are normally dark colored organic macromolecules with a high molecular weight, a complex structure consisting of aromatic and aliphatic compounds, which have a large number of functional groups containing oxygen, e.g., carboxylates (-COOH), phenolics (aromatics-OH), alcoholics (-OH), quinones (aromatics=O), among others. 1,2 Depending on the water solubility, AHS can be operationally separated into three fractions: fulvic acids that are soluble in all pH range, humic acids that are soluble in alkaline pH and insoluble in acid pH, and humin that is insoluble in all pH range. It is worth noting that the AHS comprise about 40-60% ...

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Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

Section: Ahs-metal Complexation Capacity and Determination Of The Conmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo

Toffoli

Moreira

et al. 2012

J. Braz. Chem. Soc.

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Enzymatic release of amino acids from different humic substances

Jahnel

Frimmel

1995

Acta hydrochim. hydrobiol.

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Humic substances isolated from water, sediment, and soil were characterized by applying elemental analysis, spectroscopic analysis, and gelchromatographic molecular size distribution. In addition, the amounts and pattern of enzymatically released amino acids were determined. Depending on the origin of the humic substances, the percentage of released amino acid nitrogen related to the total nitrogen was in the range of 0.4 to 26.7Yo. The samples particularly differed in the content of leucine und tyrosine. The total amount of released amino acids was compared with the results obtained from the other characterization methods. This approach indicated that humic substances with a high content of hydrolysable amino acids had high N/C and O/C ratios and low molecular sizes. Beside this, the absorption of these substances in the UV and visible wavelength range was quite low, while the measured ratios of SAK(254)/SAK(436) showed high values. This work leads to the conclusion that the extent of enzymatically releasable amino acids is not only dependant on the nitrogen content of humic substances. Other physical and chemical properties have to be considered for the understanding of the results obtained by the described biochemical characterization method.

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In vitro studies on the interactions of blood lipid level‐related biological molecules with gallic acid and tannic acid

Zeng

Sheng

et al. 2019

J Sci Food Agric

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BACKGROUND To provide the scientific evidence for a possible new mechanism of hypolipidemic effects of gallic acid (GA) and tannic acid (TA), the binding capacity of GA and TA with blood lipid level‐related biological molecules, including fat, cholesterol and cholates, were investigated in vitro. Additionally, we attempted to study the interactions of cholates with GA and TA by spectroscopic methods, high‐performance liquid chromatography electrospray‐ionization mass spectrometry (HPLC‐ESI‐MS) analysis and molecular modeling studies. RESULTS Our results demonstrated that both GA and TA were capable of binding with the blood lipid level‐related biological molecules in vitro. The fat‐binding capacity of TA was 122.1% that of GA when the addition of polyphenol was 90 mg. The inhibitory effects of GA and TA on the cholesterol solubility in mixed micelles and liquid egg yolk exhibited a dose‐dependent relationship (0.5–2.0 mg mL−1). In cholate‐binding tests, TA showed higher affinity for sodium cholate than GA at a concentration of 2.0 mg mL−1, while no significant difference in the affinity for sodium deoxycholate was found between GA and TA. Moreover, the data of spectroscopic methods, HPLC‐ESI‐MS analysis and molecular modeling studies indicated that GA and TA might precipitate cholates through hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds. CONCLUSION The findings of the present study suggested that the binding capacity of GA and TA with blood lipid level‐related biological molecules might play a crucial role in their hypolipidemic effects in animals. © 2019 Society of Chemical Industry

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Chemical and biological studies on environmental humic acids

Cited by 89 publications

References 8 publications

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Enzymatic release of amino acids from different humic substances

In vitro studies on the interactions of blood lipid level‐related biological molecules with gallic acid and tannic acid

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