Black carbon （BC） can strongly adsorb hydrophobic organic compounds （HOCs）. The HOC sorption to coated BC could be attenuated in soil and sediment compared with that of the parent BC. To study the potential causes...Black carbon （BC） can strongly adsorb hydrophobic organic compounds （HOCs）. The HOC sorption to coated BC could be attenuated in soil and sediment compared with that of the parent BC. To study the potential causes of the sorption attenuation, humic acid （HA） and BC were isolated. Phenanthrene （PHE） was selected as the representative of HOCs. BC was coated with the precipitated HA. The PHE sorption to the HA-coated BC was determined. The HA coatings on BC could result in the significant sorption attenuation of PHE to BC. The attenuation varied in different HA origin and was positively correlated to the aromaticity of HA. The attenuation could be explained by the direct competition between HA and PHE for the available sorption sites on BC and the reduction of the available sorption sites as a result of the pore blockage of BC caused by the HA coatings. Therefore, the HA coatings on BC was one potential cause of the attenuation of HOC sorption to BC in soil and sediment.展开更多
The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shi...The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shiny black surface on mirrors was the product of the soil corrosion of the bronze mirrors. It is formed by reaction between the alloy and the humic acid in soil, and leaching of copper and lead oxides through a long period of time when the mirrors were buried under the ground. A dense cormsion-resistallt layer on the bronze mirrors consisted predominantly of stannic oxide.展开更多
Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultr...Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FT-IR） were applied to study the fluorescence characteristics and structure of two typical soil HAs in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05mol L^-1 NaNO3 did not affect the 3DEEM of HA. The concentration of HA and pH of the test solution had obvious effects on the 3DEEM. When the concentration of soil HA was lower than 10mg L^-1, HA has only one obvious fluorescence peak. However, there were several fluorescence peaks for HA in high concentration （≥50mg L^-1）, and its Ex/Em maximum wavelength shifted towards longer wavelength with increasing the concentration of HA. The fluorescence intensity of HA enhanced with the increase of pH, and achieved maximum at pH 10. The effect of pH on the fluorescence intensity of black soil HA （BHA） was the severest and a polycondensation of BHA existed with the change of pH. At the same condition, the fluorescence intensity of red soil HA （RHA） was stronger than that of BHA. At the excitation wavelength of 340nm, the maximum emission peak positions of RHA and BHA were 474 and 504nm at pH 6.0, and their fluorescence quantum yields （QY） were 2.1-2.5% and 1.5-1.9%, respectively. Based on the maximum emission peak positions and fluorescence quantum yield, RHA and BHA can be distinguished.展开更多
The formation of the black patina induced by soil humic asid under different conditions was studied, theblack, grey and brown colored shiny surfaces prepared in laboratory were analyzed. As a result the formation ofti...The formation of the black patina induced by soil humic asid under different conditions was studied, theblack, grey and brown colored shiny surfaces prepared in laboratory were analyzed. As a result the formation oftin-rich shiny black surface on bronze mirrors is the product of soil corrosion of the bronze mirrors. The patina isformed by reection between the alloy and the humic acid in soil, and leaching of copper and lead oxides through along period time when the mirrors were buried under the ground leaving a dense compact corrosion-resistant layerconsisted predominantly of stannic oxide microcrystal.展开更多
基金Project supported by the Natural Science Foundation of Shandong Province (No.Y2003B04).
文摘Black carbon （BC） can strongly adsorb hydrophobic organic compounds （HOCs）. The HOC sorption to coated BC could be attenuated in soil and sediment compared with that of the parent BC. To study the potential causes of the sorption attenuation, humic acid （HA） and BC were isolated. Phenanthrene （PHE） was selected as the representative of HOCs. BC was coated with the precipitated HA. The PHE sorption to the HA-coated BC was determined. The HA coatings on BC could result in the significant sorption attenuation of PHE to BC. The attenuation varied in different HA origin and was positively correlated to the aromaticity of HA. The attenuation could be explained by the direct competition between HA and PHE for the available sorption sites on BC and the reduction of the available sorption sites as a result of the pore blockage of BC caused by the HA coatings. Therefore, the HA coatings on BC was one potential cause of the attenuation of HOC sorption to BC in soil and sediment.
文摘The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shiny black surface on mirrors was the product of the soil corrosion of the bronze mirrors. It is formed by reaction between the alloy and the humic acid in soil, and leaching of copper and lead oxides through a long period of time when the mirrors were buried under the ground. A dense cormsion-resistallt layer on the bronze mirrors consisted predominantly of stannic oxide.
基金Acknowledgements： This work is supported by the Project of the Educational Administration Foundation of Shanghai Municipal Government （No. 05Ja05054 and No. 05DZ01）, Shanghai Leading Academic Discipline Project （No. T0402） and Hunan Provincial Natural Science Foundation of China.
文摘Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FT-IR） were applied to study the fluorescence characteristics and structure of two typical soil HAs in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05mol L^-1 NaNO3 did not affect the 3DEEM of HA. The concentration of HA and pH of the test solution had obvious effects on the 3DEEM. When the concentration of soil HA was lower than 10mg L^-1, HA has only one obvious fluorescence peak. However, there were several fluorescence peaks for HA in high concentration （≥50mg L^-1）, and its Ex/Em maximum wavelength shifted towards longer wavelength with increasing the concentration of HA. The fluorescence intensity of HA enhanced with the increase of pH, and achieved maximum at pH 10. The effect of pH on the fluorescence intensity of black soil HA （BHA） was the severest and a polycondensation of BHA existed with the change of pH. At the same condition, the fluorescence intensity of red soil HA （RHA） was stronger than that of BHA. At the excitation wavelength of 340nm, the maximum emission peak positions of RHA and BHA were 474 and 504nm at pH 6.0, and their fluorescence quantum yields （QY） were 2.1-2.5% and 1.5-1.9%, respectively. Based on the maximum emission peak positions and fluorescence quantum yield, RHA and BHA can be distinguished.
文摘The formation of the black patina induced by soil humic asid under different conditions was studied, theblack, grey and brown colored shiny surfaces prepared in laboratory were analyzed. As a result the formation oftin-rich shiny black surface on bronze mirrors is the product of soil corrosion of the bronze mirrors. The patina isformed by reection between the alloy and the humic acid in soil, and leaching of copper and lead oxides through along period time when the mirrors were buried under the ground leaving a dense compact corrosion-resistant layerconsisted predominantly of stannic oxide microcrystal.
