Synthesis of Humin-based Carbon Quantum Dots and Luminescent Properties

The unique properties of carbon quantum dots(CQDs) make them promising materials in many fields. Herein, we present a facile method for the preparation of photo-luminescent CQDs using humins as the carbon precursor for the purpose of providing a high value-added solution for this "biomass conversion process waste". The structure of the CQDs was analyzed, and the effects of reaction temperature and time on the CQDs' fluorescence were investigated. The results showed that humins were effectively carbonized during the reaction. The fluorescence intensity of humin-based CQDs initially increased with reaction temperature and time, and subsequently decreased beyond 200℃ and 4 h. Polyaromatic structures and hydrophilic groups such as O—H, C—O, —COOH and C==O groups exist in the CQDs. The huminbased CQDs have the dimension of 3～7 nm with an average size of about 5.5 nm. The highest emission intensity of blue/cyan fluorescence light at 440 nm is achieved on the excitation with UV light at the wavelength of 330 nm.

Carbon Sequestration in Soil Humic Substances Under Long-Term Fertilization in a Wheat-Maize System from North China

The changes in humic substances （HS） is fundamental in detecting soil carbon sequestration mechanisms in natural and cultivated environments. Based on a long-term trial, the amounts of water dissolved substances （WSS）, humic acid （HA）, fulvic acid （FA） and humin （HU） were determined to explore the impact of long-term fertilization on HS. Increases in the amounts of WSS, HA, FA and HU were significant different among the treatments with manure. A significant correlation was found between the increased soil organic carbon （SOC） and HS （R^2=0.98, P〈0.01）. The change in the E4/E6 ratio was significantly correlated with the increased SOC （R2=0.88, P〈0.01）, HA （R^2=0.91, P〈0.01）, FA （R^2=0.91, P〈0.01） and HU （R^2=0.88, P〈0.01）. The cluster was mainly divided into two parts as manure fertilization and inorganic fertilization, based on the increases in HA, FA and HU. These results suggest that long term fertilization with manure favours carbon sequestration in HS and is mainly stabilized as HU, while the HA becomes more aliphatic. We conclude that increases in SOC can be linked to changes in the molecular characteristics of HS fractions under long term fertilization.

紫色土丘陵坡地5种土地利用方式土壤腐殖物质特征比较

以衡阳紫色土的天然草地(Natural grassland,NG)、人工草地(Tame grassland,TG)、灌草地(Frutex and grassland,FG)、灌丛地(Frutex,FX)和乔灌地(Arbor and frutex,AF)5种土地利用方式的土壤为研究对象,分析5种土地利用方式土壤的腐殖物质(Humic substance,HS)组成和性质,并探讨与土壤理化性质之间的关系。研究发现:FG的腐殖物质含量最高,其次为TG,NG最低;土壤腐殖物质总碳(Total carbon,T-C)以胡敏素碳(Humin carbon,Hu-C)含量最高,胡敏酸碳(Humic acid carbon,HA-C)含量最低;TG与FG的胡敏酸碳/富里酸碳[Humic acid carbon/Fulvic acid carbon,(HA-C)/(FA-C)]含量最高,NG最低,TG,FG,FX与AF 0~20 cm土层的(HA-C)/(FA-C)含量显著高于20~40 cm土层(P<0.05);5种土地利用方式的HS,HA-C,富里酸碳,Hu-C,土壤有机碳(Soil organic carbon,SOC),碱解氮(Alkali-hydrolyzable nitrogen,AN)与速效磷(Available phosphorus,AP)两两间呈显著或极显著正相关关系(P<0.05或P<0.01),土壤pH值与HS,HA-C,FA-C,Hu-C,SOC,AN,AP呈显著负相关关系(P<0.05)。研究结果表明,NG的HS组分含量较低,土质较差,而TG,FG的HS含量较高,土质较好,建议将NG开发成TG与FG土地利用方式,以提高土壤肥力。

不同有机物配施化肥对植烟土壤腐殖质碳的影响

探讨了不同有机物配施化肥对植烟土壤腐殖质碳的影响,旨在为衡量和评价不同有机物对植烟土壤质量和肥力的影响提供科学依据。结果表明,与单施化肥(T_1)处理相比,总体上腐熟麦秸秆(T_2)、生物炭(T_3)、芝麻饼肥(T_4)、牛粪(T_5)配施化肥处理土壤腐殖质总碳、富里酸碳、胡敏素碳的含量均有不同程度升高,增幅分别为13.71%、9.31%、12.57%、28.10%,24.35%、6.30%、13.73%、14.80%,10.93%、16.11%、3.96%、26.27%,另外,T_2、T_4、T_5处理土壤胡敏酸碳含量增加,增幅分别为10.56%、66.14%、103.93%;T_4、T_5处理土壤胡/富分别提高32.20%、63.93%,PQ(胡敏酸在腐殖酸中所占的比例)分别提高22.96%、48.95%。综上,有机物配施化肥能改善土壤腐殖质碳组分,牛粪配施化肥处理效果最好,生物炭表现最差。

澧阳平原埋藏古水稻土腐殖质组成及空间分布特征研究

为了探明埋藏古水稻土的腐殖质组分特征以及空间分布规律,采用野外采样和室内分析相结合的方法,以澧阳平原杉龙岗遗址古水稻土为材料,选取3处剖面(PA、PB、PC),比较分析了各剖面中现代耕作水稻土层和埋藏古水稻土层的有机碳、胡敏酸(HA)、富里酸(FA)和胡敏素(HU)等含量变化情况。结果表明:杉龙岗遗址古水稻土腐殖质各组分含量为胡敏素>胡敏酸>富里酸;随着土层深度的增加,在现代耕作水稻土中各组分含量表现为波动性降低趋势,而在埋藏古水稻土中呈现微幅增加趋势;现代耕作水稻土中耕作层腐殖质累积速度较快,从上到下的迁移量相对较大,而埋藏古水稻土中各形态腐殖质含量变化相对较小,并且朝着更加稳定的趋势变化。

泥炭和褐煤对土壤有机碳和腐殖物质组成的影响

在相同温湿度环境条件下,研究泥炭和褐煤与土壤混合后对土壤有机碳及其腐殖物质组成变化的影响,为改善耕地土壤有机碳库的管理提供理论依据。结果表明:随着培养时间的延长,添加褐煤、木本泥炭的土壤有机碳含量分别上升了0.66%和17.41%,添加草本泥炭的土壤有机碳含量下降了3.15%;胡敏酸含碳量呈逐渐增加的趋势,富里酸含碳量呈逐渐减小的趋势;添加草本泥炭的胡敏素含碳量呈下降趋势,添加褐煤和木本泥炭的土壤胡敏素含碳量呈逐渐上升趋势。土壤胡富比和PQ值整体上都表现出随着培养时间的延长而逐渐增加的趋势。由此可知,泥炭和褐煤能提高土壤有机碳,改良土壤腐殖物质组分,且添加木本泥炭的土壤有机质含量和腐殖物质组分改善效果最好。

中国东部森林土壤腐殖碳组分纬度格局及其影响因素（英文）

Soil humic carbon is an important component of soil organic carbon （SOC） in ter- restrial ecosystems. However, no study to date has investigated its geographical patterns and the main factors that influence it at a large scale, despite the fact that it is critical for exploring the influence of climate change on soil C storage and turnover. We measured levels of SOC, humic acid carbon （HAC）, fulvic acid carbon （FAC）, humin carbon （HUC）, and extractable humus carbon （HEC） in the 0-10 cm soil layer in nine typical forests along the 3800-km North-South Transect of Eastern China （NSTEC） to elucidate the latitudinal patterns of soil humic carbon fractions and their main influencing factors. SOC, HAC, FAC, HUC, and HEC increased with increasing latitude （all P〈0.001）, and exhibited a general trend of tropical 〈 subtropical 〈 temperate. The ratios of humic C fractions to SOC were 9.48%-12.27% （HAC）, 20.68%-29.31% （FAC）, and 59.37%-61.38% （HUC）. Climate, soil texture, and soil microbes jointly explained more than 90% of the latitudinal variation in SOC, HAC, FAC, HEC, and HUC and interactive effects were important. These findings elucidate latitudinal patterns of soil humic C fractions in forests at a large scale, and may improve models of soil C turnover and storage.

胡敏素基活性炭的制备及电化学性能研究

以生物质酸水解的固体废弃物胡敏素为原料,KOH为活化剂,经活化和炭化制备得到胡敏素基活性炭材料,并通过XRD、FTIR、N2物理吸脱附、SEM、TGA等表征技术对样品的结构和形貌进行分析;还通过循环伏安法和恒流充放电法分析了样品的电化学性能。结果表明:胡敏素基活性炭材料比表面积大且热稳定性能良好。其中,在900℃下炭化的AC-900样品比表面积最大达1732.57 m_(2)/g,在1100℃下炭化的AC-1100样品在电流密度为1 A/g下比容量高达364 F/g,在电流密度为9A/g下比容量也达175 F/g。本文研究结果表明所制备的胡敏素基活性炭在超级电容器领域具有良好的应用潜力。