石油污染土壤中高效石油烃降解菌Y-16的筛选及其降解性能

通过富集和驯化培养从石油污染的土样中筛选出一株高效石油烃降解菌Y-16,其对胜利原油7 d降解率达到51.98%。在好氧条件下,对Y-16菌株的最优降解条件进行了探索,结果表明,在pH值8.0,温度30℃,接种量10%,摇床转数160 r/m in和3 000~7 000 mg/L的底物浓度下,Y-16菌株的最高降解率可达到60.34%。通过Y-16菌株对石油烃降解规律的探索,发现Y-16菌株对石油烃的降解符合一级反应动力学模型。     

鼠李糖脂在铜绿假单胞菌NY3代谢烃过程中的生理作用

为了解鼠李糖脂在菌代谢烃过程中所起的具体作用,对NY3菌体生理生化指标进行测定,研究了NY3菌降解烃过程中,鼠李糖脂促进烃降解与细胞生理特性变化规律的相关性。结果表明,投加60、100和140 mg/L鼠李糖脂,能使正十六烷降解率分别提高23.7%、48.3%和32.2%,且产酸明显。鼠李糖脂能加快疏水性有机物的传质速度,与未加鼠李糖脂相比,鼠李糖脂浓度为100和140 mg/L时,菌细胞内积聚的正十六烷量增加12.5%和37.69%。鼠李糖脂存在下,NY3菌细胞内正十六烷吸收是一个积累和消耗相互交替的动态过程。鼠李糖脂使菌体细胞中疏水性脂类的相对含量和细胞表面的负电荷明显增加,但使所生长的细胞内脂多糖含量明显减少,生长过程投加鼠李糖脂浓度为60、100、140和200 mg/L时,细胞中脂多糖含量分别减少45.65%、58.13%、45.61%、和59.44%。因此,鼠李糖脂能加快NY3菌对十六烷的降解,同时对代谢过程中菌体的生理生化特性有明显的改变。     

磁河有机污染物在饱和土壤中迁移转化试验研究

通过静态吸附、静态降解和动态土柱试验,研究了磁河废水中有机污染物在土壤饱水条件下的迁移转化行为.实验结果经线性拟合和参数估算,得到弥散系数D=0.0036m2/d,分配系数K_d=0.19cm3/g,降解系数K=0.68 d-1.表明磁河有机污染物在土壤中有较强的吸附和降解能力.      

高效液相色谱法测定多环芳烃化合物辛醇/水的分配系数及其对水溶解度的估算

本文采用反相高效液相色谱法间接测定了29种多环芳烃化合物的辛醇/水分配系数,并估算其水溶解度,所得结果与文献值和计算值基本一致。     

大庆地区总悬浮微粒中苯溶物及多环芳烃的测定与评价

通过对大庆地区总悬浮微粒（TSP）中主要化学组成──苯溶物、多环芳烃的测定分析得知：苯溶物占TSP的百分含量，年均值为10．31％，在空气中的平均浓度为12．5μg／m3。与北京燕山地区1983～1984年3个生活区（迎风、东风、东炼）苯溶物年平均值比较，大庆地区苯溶物含量较低。而对总悬浮微粒中多环芳烃的测定结果可明显看出各点采暖期苯并（a）芘、多环芳烃总量的浓度虽都明显高于非采暖期，但其致癌强度和浓度都比北京市、太原市及兰州市弱、低。     

Saturated and Unsaturated Water Flow in Inclined Porous Media

This paper considers the two-dimensional saturated and unsaturated flow of water through inclined porous media, namely a waste dump or hill slope. Since the partial differential equation governing this water flow transforms from being parabolic to elliptic as the water flow varies from unsaturated to saturated, an iterative, finite differencing scheme is used to develop a numerical solution. The model can be used to investigate the effects that hill slope angle, depth of soil cover and hilltop width have on water accumulation in the dump and the time required for saturation to occur at different areas in the dump domain. The accuracy and reliability of the computer based solution is tested for two different boundary conditions – (1) no flow on all boundaries (i.e., the internal redistribution of soil moisture to steady state) and (2) a constant rainfall flux on the dump surface. Numerical studies then show the effects of changing the hill slope angle, depth of layer, and dump geometry on the flow characteristics in the dump.     

Thymic involution produced by diesel exhaust particles and their constituents in mice

Epidemiological studies suggest that diesel exhaust particles (DEP) contribute to an increase in allergic diseases. To assess the effects of DEP on the central immune system, mice were exposed to DEP by intraperitoneal (IP) administration. Exposure to DEP resulted in severe thymic involution accompanied by a reduction in the number of thymocytes, especially in cortical CD4⁺CD8⁺ double positive and double negative subsets. Core carbon particles associated with a mixture of chemical compounds in DEP did not appear to be responsible for the DEP-induced thymic involution because carbon graphite does not affect neither the number nor the CD4/CD8 profile of thymocytes. Extraction of DEP by ether, acidic and basic solvents showed that several independent fractions including the neutral ether fraction, which contains polycyclic aromatic hydrocarbons (PAH), induced thymic involution. Among major PAH components of DEP, benzo[b]fluoranthene (BbF), benzo[a]pyrene (BaP), and benzo[k]fluoranthene (BkF) were very potent inducers of thymic involution at an ED50 of less than 100?ng per mouse body. Nonetheless, DEP treatment of mice with targeted disruption of genes encoding the aryl hydrocarbon receptor (AHR), AHR nuclear translocator (ARNT), or microsomal epoxide hydolase (mEH) indicated that DEP produced thymic involution even in the absence of PAH-induced AHR/ARNT signal transduction or mEH-mediated PAH catabolism. On the other hand, BaP-mediated thymic involution was completely dependent on AHR, partially dependent on ARNT in T cells, and independent of mEH. These results indicate that DEP-induced thymic involution is mediated both by PAH-AHR/ARNT-dependent and -independent mechanisms.     

Dissipation of polycyclic aromatic hydrocarbons and microbial activity in a field soil planted with perennial ryegrass

Dissipation and plant uptake of polycyclic aromatic hydrocarbons (PAHs) in contaminated agricultural soil planted with perennial ryegrass were investigated in a field experiment. After two seasons of grass cultivation the mean concentration of 12 PAHs in soil decreased by 23.4% compared with the initial soil. The 3-, 4-, 5-, and 6-ring PAHs were dissipated by 30.9%, 25.5%, 21.2%, and 16.3% from the soil, respectively. Ryegrass shoots accumulated about 280 μg·kg^-1, shoot dry matter biomass reached 2.48 × 10⁴ kg·ha^-1, and plant uptake accounted for about 0.99% of the decrease in PAHs in the soil. Significantly higher soil enzyme activities and microbial community functional diversity were observed in planted soil than that in the unplanted control. The results suggest that planting ryegrass may promote the dissipation of PAHs in long-term contaminated agricultural soil, and plant-promoted microbial degradation may be a main mechanism of phytoremediation.     

土壤中多环芳烃的稳定碳同位素特征及其对污染源示踪意义

分析了天津市不同功能区土壤中多环芳烃的稳定碳同位素组成特征、土壤中菲、甲基菲、荧葸和芘的δ^13C值范围分别为-29．5‰～-23．2‰、-39．8‰～-23．4‰、-27．2％～-23．6‰和-28．1‰～-22．6‰,不同功能区稳定碳同位素组成的差异反映了PAHs来源的差异．稳定碳同位素组成特征表明,在研究区内,化石燃料燃烧产物的干-湿沉降是土壤PAHs的最主要来源之一,其它可能的来源有污水携带的油污、农作物茎杆及薪柴不完全燃烧产物等．就具体地点而言,土壤PAHs以二元混合输入为主,据此,运用稳定碳同位素组成的二元复合数值模型对不同来源PAHs的相对贡献率进行了估算