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951.
基于δ18O的青藏高原中部错那湖湖水蒸发研究 总被引:1,自引:1,他引:1
稳定同位素方法经常被用来估算湖水水量平衡,这种方法主要依赖于水样的采集和同位素分析,并结合研究区域相关的气候和水文信息对湖水进行研究。基于对1999-2001年期间获得的18个湖水样的稳定同位素分析,发现错那湖水δD和δ18O的平均值分别为-83.3‰和-9.6‰,显著高于流域内同期降水中δD和δ18O的加权平均值-124.5‰和-16.6‰;流域内湖水稳定同位素的变化幅度远小于降水,但展示了明显的季节变化,夏季值较低而冬春季值较高,这种变化表现出一定的降水量效应,表明降水是湖水主要补给来源之一。结合所获得的流域内降水和河水稳定同位素数据,利用稳定同位素质量平衡方法对非结冰期间错那湖水的蒸发与流入比率(E/I)进行了估算,结果表明,受太阳辐射与气温升高的影响,湖水受到强烈的蒸发,流入错那湖的水大约24%消耗于蒸发。 相似文献
952.
Enzymes play essential roles in the biological processes of sludge treatment. In this article, the ultrasound method to extract enzymes from sludge flocs was presented. Results showed that using ultrasound method at 20 kHz could extract more types of enzymes than that ultrasound at 40 kHz and ethylenediamine tetraacetic acid (EDTA) methods. The optimum parameters of ultrasound extraction at 20 kHz were duration of 10 min and power of 480 W. Under the condition, ultrasound could break the cells and extract both the extracellular and intercellular enzymes. Ultrasound power was apparently more susceptive to enzyme extraction than duration, suggesting that the control of power during ultrasound extraction was more important than that of duration. The Pearson correlation analysis between enzyme activities and cation contents revealed that the different types of enzymes had distinct cation binding characteristics. 相似文献
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Several main metabolites of benzo[a]pyrene (BaP) formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone (BP 1,6- quinone), trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP 7,8-diol), 3-hydroxybenzo[a]pyrene (3-OHBP), were identified by high-performance liquid chromatography (HPLC). The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that (1) the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; (2) the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; (3) the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% (w/v), concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites. 相似文献
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对COD_(Cr)测定中干扰因素及其消除方法的探讨 总被引:1,自引:0,他引:1
针对CODCr测定中,对消除氯离子、亚硝酸根、亚铁离子和硫离子等干扰因素进行分析探讨,结果表明,所采用方法科学、可靠,并可以获得满意的结果。 相似文献
960.
Succession of aquatic microbial communities as a result of the water quality variations in continuous water 总被引:1,自引:0,他引:1
The changes of structural and functional parameters of aquatic microbial communities in continuous water on campus of Tsinghua University, China are investigated by polyurethane foam unit(PFU) method. The measured compositions of the communities include alga, protozoa, and some metazoa (such as rotifers). The measured indicators of water quality include water temperature, pH value, dissolved oxygen (DO), potassium permanganate index(CODMn), total nitrogen(TN), total phosphorus(TP) and chlorophyll- a(Chla). The trophic level, expressed by the trophic level indices(TL/c), is assessed with analytic hierarchy process and principal component analysis (AHP-PCA) method. The changing trends of the structural and functional parameters of aquatic microbial communities, such as Margalef index of diversity(D), Shannon-weaver index of diversity (H), Heterotropy index (HI), number of species when the colonization gets equilibrium(Seq), colonizing speed constant(G) and time spent when 90 percent of Seq colonized in PFU ( T90% ), are also analyzed. The experimental results showed the succession of aquatic microbial communities along the water flow is consistent with the water quality changes, so the parameters of microbial community can reflect the changes of water quality from the ecological view. 相似文献