The influence of texture, bulk density, and organic matter content on the process of nitrate vertical transport in the three main paddy soils (Bai soil, Huangni soil and Wushan soil) of the Tai Lake region were studied in the soil columns. Breakthrough curves (BTC) were obtained separately for each of thirteen horizons. The results were as follows: vertical transport velocity of nitrate decreased, and the BTCs of nitrate were more dispersed, in each horizon from the surface layer to the bottom in every soil profile. Among the three soils, the average flux ofWushan soil was the least and its nitrate BTC was the most dispersed. Under saturated conditions, nitrate penetrated the soil column quickly. The transport of nitrate was affected by clay content. As the clay content increased, nitrate outflow was retarded, and the peak concentration was reduced. Nitrate BTCs rose and fell gently when the nitrate concentration was lower. All nitrate BTCs were asymmetric, and tailing was more obvious when clay content was high. Soil bulk density and the organic matter content also affected the vertical transport of nitrate. Low bulk density and high organic matter content were each associated with faster nitrate transport. An analytical solute transport model (CXTFIT 2.0) was used to estimate the nitrate dispersion coefficient and average pore-water velocity from the observed breakthrough curves. The results showed that the analytical solute transport model was suitable in fitting the observed nitrate transport in these soils. The dispersion coefficient was found to be a function of average pore-water velocity.

在温室盆栽条件下，通过单独或联合添加生物表面活性剂鼠李糖脂（RH）和接种多环芳烃专性降解菌（DB），研究了利用生物表面活性剂-微生物强化紫花苜蓿（Medicago sativa L.）修复多环芳烃（PAHs）长期污染土壤的效果。结果表明，添加鼠李糖脂和接种PAHs专性降解菌能促进紫花苜蓿的生长和土壤中PAHs的降解。培养90d后，RH、DB处理的PAHs的降解率分别为30.0%和49.6%，均高于对照处理（CK）（21.7%）。RH+DB处理PAHs的降解率最高达53.9%，说明鼠李糖脂和PAHs专性降解菌协同作用显著。另外，随着PAHs苯环数的增加，其平均降解率逐渐降低，但是接种PAHs专性降解菌能够提高4环和5环PAHs的降解率。同时也发现土壤中脱氢酶活性和PAHs降解菌数量越高的处理，土壤PAHs的降解率也越高。所以添加鼠李糖脂和接种PAHs专性降解菌能够有效促进土壤多环芳烃降解。

The characteristics of nitrate horizontal transport in a major paddy soil, Wu Shan soil in the Tai Lake region, were studied. The concentration of nitrate during horizontal movement decreased with the increasing in distance from the tracer source, the change following a logarithmic function. The concentration of the nitrate was strongly correlated with the soil moisture content, as an exponential function. The horizontal transport velocity of nitrate was significantly correlated with the distance of the tracer source as power function. Therefore, the velocity of nitrate horizontal transport was controlled by the concentration gradient of nitrate, and soil water potential gradient from beginning to the 20 cm mark in the horizontal column. However, the velocity of nitrate horizontal was stable beyond 20 cm, where it was controlled by soil matric potential.

土壤中氧化铁的组成反映了土壤的成土过程和环境条件。通过对西南喀斯特石漠化地区不同石漠化阶段山地自然土壤和农田土壤Fe组成的分析，研究了土壤全铁、游离氧化铁和非晶形氧化铁的分布规律，探讨了喀斯特地区石漠化土壤的发育过程和Fe的指示作用。研究表明：①喀斯特地区土壤表层全铁含量在38.9～53.9g/kg之间，游离氧化铁含量在18.0～26.7g/kg之间，铁游离度在44.1%～73.4%之间，铁活度在7.2%～11.4%之间。②随着石漠化程度的加剧，土壤游离氧化铁和铁游离度呈增加的趋势，而铁活度呈降低的趋势。③在土体分布上，自然土壤剖面随深度的增加，土壤铁游离度和铁活度呈明显降低的趋势，而农田土壤铁游离度呈增加的趋势。④喀斯特地区的土壤是石灰岩溶蚀风化的产物，人为活动干扰下的自然土壤石漠化过程是在水力作用下的表土侵蚀过程，而农田土壤受水分垂直运动的影响，是土壤丢失的过程。

通过采集我国西南喀斯特地区不同石漠化阶段典型土壤样品，研究了土壤有机质组分及其影响因素。结果表明：（1）喀斯特地区土壤有机质各组分含量中胡敏素>富里酸>胡敏酸，HA/FA一般<014，为富里酸土壤，与同水平地带土壤一致。（2）石漠化过程对喀斯特地区土壤中有机质组成有明显的影响，土壤中胡敏素、富里酸与胡敏酸表现出未石漠化>潜在石漠化>轻度石漠化>中度石漠化的趋势。（3）喀斯特地区土壤有机质组分空间分布有较大差异，剖面层次上各有机质组分胡敏素、富里酸与胡敏酸均表现出表土层>底土层，山区不同部位上表现以山坡中下部有机质含量最高，而以山顶最低，且FA/HA表现出从山顶到山脚有明显增加的趋势。（4）喀斯特地区土壤土壤有机碳、酸碱度、碳酸钙、容重、非晶形氧化铝、颗粒组成、有效磷与土壤有机碳组分间表现出显著或极显著的相关性，土壤有机碳和质地是影响土壤有机碳组分含量的主要因素。