中文摘要：

通过盆栽试验分析了胡敏酸输入土壤6个月后茶树根际和非根际土壤有机质（SOM）及其组分，包括水溶性物质（WSS）、富啡酸（FA）、胡敏酸（HA）以及土壤微生物生物量（SMB）的变化，并对不同土壤有机质组分碳含量和茶树不同组织铅含量作了相关性分析。外源胡敏酸设置3个浓度水平（0、300、600 mg kg-1），铅设置2个浓度水平（0、300 mg kg-1），试验共有6个处理。茶苗置于温室培养，6个月后分新叶、老叶、新茎、老茎、根收获。结果表明：根际并非总是富含有机质，未加铅处理根际土壤总有机碳（SOC）含量低于非根际；而加铅处理根际SOC含量高于非根际。HA加入土壤能够显著增加根际和非根际SOC和SMB的含量，但是加铅处理和不加铅处理增加幅度不同。高浓度HA显著增加了根际FA的含量，可能是HA部分裂解所致。非根际有机质各组分与茶树铅含量无显著相关关系；根际SOC、HA和茶树不同组织铅含量没有显著相关关系。根际WSS、FA与茶树嫩叶、老叶、嫩茎、老茎以及根部铅含量均存在显著或极显著正相关关系；而根际SMB与茶树各个组织铅含量存在显著负相关关系。总之，胡敏酸施入土壤改变了土壤有机质及其各个组分的含量，而根际某些土壤有机质组分的改变又显著影响了茶树不同组织铅的吸收和分布。

英文摘要：

Soil organic matter （SOM） plays a vital role in regulating metal bioavailability. However, the relationship of SOM and its fractions, including water soluble substance （WSS）, fulvic acid （FA）, humic acid （HA）, and soil microbial biomass （SMB）, with metal bioavailability to plants has not yet been thoroughly investigated. A pot experiment was carried out to explore effects of exogenous humic acid on soil organic carbon （SOC）,its composition and soil microbial biomass （SMB） in rhizosphere and bulk soils, 6 months after its application, and correlation analysis done of carbon content in each fraction of the soil SOC with Pb content in various parts of the tea plant. The experiment, using yellow-red soil collected from Fuyang, was designed to have three levels of HA application rate （0, 300 and 600 mg kg-1 DW） and two levels of Pb concentration （0 and 300 mg kg-1）, making up a total of 6 treatments. After the pots, 3 kg of air-dried yellow red soil each, were amended separately with Pb, they were left for aging for 30 days. Then each pot had four uniform seedlings transplanted in. After successful transplantation, three levels （0, 300, and 600 mg kg-1 DW） of HA were amended separately with irrigation. Six months later, the plants were harvested separately by new leaf, old leaf, new shoot, old shoot and root, for analysis of Pb concentrations in these tissues of the plants. SOC, WSS, FA, HA and SMB in the rhizosphere and bulk soils in the pots were extracted and quantified using a Multi N/C Total Organic Carbon Analyzer. Results show that in the pots that had not been spiked with Pb, the rhizospheric soil was lower than the bulk soil in SOC, whereas in the pots that had, a reverse trend was observed. Amendment of HA significantly increased SOC and SMB both in the rhizospheric and bulk soils, but the effect was affected by Pb spiking. High concentration of HA significantly increased FA in the rhizosphere soil, which was probably attributed to degradation of some of the HA amended