钙对盐胁迫下水稻幼苗抗氧化酶活性和膜脂过氧化作用的影响

研究了外源Ca2 对盐胁迫下耐盐性不同的两个水稻品种(武育粳3号和IR36)几种抗氧化酶活性及膜脂过氧化的影响。结果表明:适量的Ca2 供应能有效提高水稻叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)以及抗坏血酸过氧化物酶(APX)的活性,使之维持在较高的水平上,并降低了丙二醛(MDA)含量和细胞膜透性。此外,外源Ca2 还增加了抗坏血酸(AsA)的含量,增强了水稻幼苗的根系活力。这表明适量的外源Ca2 供应提高水稻耐盐性的原因之一,在于其增强了植株的活性氧清除能力以及对细胞膜的稳定作用。     

土壤沉积物样品中有机碳含量的快速测定

采用微波密闭消解样品的方法来测定土壤／沉积物中有机碳的含量。与重铬酸钾氧化法的结果相比，微波消化法具有操作简单、污染小、快速准确的优点。经F检验法及t检验法检验，两种方法的分析结果无明显差异。     

Evaluation of alternative substrates for determining methane-oxidizing activities and methanotrophic populations in soils

The magnitude of methane emission is a net result of methane production and the oxidation rate. The possibility of measuring oxidized products of alternative substrates of methane monooxygenase was examined to determine methane-oxidizing ability of soils, and to count methanotrophic populations in soils. Wetland rice soils were incubated under methane containing air to enirch the methanotrophs. Methane loss and oxygen uptake were inhibited by acetylene, dimethylether, and nitrapyrin (N-Serve). Acetylene was used routinely, because it inhibited methane oxidation even at a low concentration of 0.03 to 0.06 l ml^-1 in the incubation headspace. Propylene at 10 kPa was used as an alternative substrate of methane monooxygenase, and the formation of propylene oxide was measured. When soils were incubated under methane, their methane-oxidizing activity increased. Propylene oxide formation increased simultaneously. Acetylene also blocked propylene oxidation. The results of several experiments and propylene oxide formation (r=0.87 after long-transformation). These results indicate that propylene oxide formation can be used as a semiquantitative measure of the methane-oxidizing activity of soils. The colonies of soluble methane monooxygenase-forming methanotrophs were counted on Cu-deficient methanotroph agar medium by the formation of naphthol from haphthalene. The counts increased from 10⁴ (0 days) to 10⁷ (21 days) g^-1 soil during oxic incubation under methane.     

Combined effect of fertilizer and herbicide applications on the abundance, community structure and performance of the soil methanotrophic community

The use of agrochemicals, such as mineral fertilizers and herbicides in agricultural systems, may affect the potential of soils to act as a sink for methane. Typically, the effect of each agrochemical on soil methane oxidation is investigated separately whereas in the field these agrochemicals are used together to form one comprehensive land management system. Here we report the results of field experiments that assessed the combined effect of multiple fertilizer and herbicide (nicosulfuron, dimethenamide and atrazine) applications on the soil methanotrophic community. Soils treated with organic fertilizer had three times higher methane oxidation rates compared to soils receiving mineral fertilizers. These higher oxidation rates were positively reflected in a significantly enhanced abundance of methanotrophs for the organic fertilized soils. In contrast, herbicide application did not alter significantly the soil methane oxidation rate or the methane-oxidizing population abundance. Subsequently, the methanotrophic community structure was analyzed with group-specific DGGE of 16S rRNA genes. Cluster analysis of the methanotrophic patterns clearly separated the mineral from organically fertilized soils. Less pronounced clustering differentiated between chemical and manual weed control. Furthermore, cluster analysis of the methanotrophic community revealed that soil type was the primary determinant of the community structure. Our results indicate that fertilizer type had the greatest influence on methane oxidizer activity and abundance. Soil type had the most pronounced effect on the microbial community structure.     

Microbial and enzyme activity in soils amended with a natural source of easily available carbon

The addition of sugar beet to soils as a source of C led to an increase in the availability of easily utilizable C (glucose), which in turn markedly increased numbers of soil bacteria and of the yeast Williopsis californica. Nitrification, P solubilization, urea hydrolysis (and the subsequent nitrification of liberated NH _inf4 ^sup+ ) were stimulated by this amendment. The stimulation of nitrification may have been a result of increased heterotrophic nitrification. In contrast, the concentration of sulphate in S^o-amended soils declined following amendment, presumably as the result of enhanced S immobilization. Activity of the enzymes amylase, aryl sulphatase, invertase, phosphatase, dehydrogenase, and urease were all stimulated by the sugar beet amendment. These results suggest that sugar beet amendment could be used to increase the rate of release of plant-available ions from fertilizers such as insoluble phosphates. Problems may arise, however, from a subsequent increase in nitrification and reduced sulphate availability.     

土壤化学中的广义氧化还原反应

 土壤化学中的酸碱反应、沉淀溶解反应、配位反应和氧化还原反应都属于广义氧化还原反应。土壤化学反应中的某些性质可用广义氧化还原理论给出新的解释。     

电化学方法处理含硫废水的过程和特性

采用管式电气浮装置处理人工模拟含硫废水并研究其过程和特性，探讨在两相厌氧处理富邻居唷酸盐高浓度有机废水工艺中采用电化学方法处理含硫废水的可行性。     

电催化氧化处理蒽醌蓝模拟染料废水试验研究

研究了pH值、槽电压、电解时间与通电方式、电解质种类及浓度对酸性蒽醌蓝模拟染料废水的电催化氧化效果。处理酸性蒽醌蓝染料废水的最佳电催化氧化条件为槽电压10V、初始pH值为4、NaCl浓度2.0g/L;在此条件下连续电解50min,COD去除率和脱色率分别为53.6%和87.9%。研究表明脉冲电催化氧化可以明显提高能量效率和电流效率,降低处理成本。     

絮凝纳米TiO_2光催化氧化法处理造纸废水的研究

应用絮凝纳米TiO2光催化氧化法对造纸废水进行了处理,并对其处理工艺进行了研究。讨论了在常温下,混凝过程中Al2(SO4)3的投加量和废水pH值以及纳米光催化氧化过程中纳米TiO2投加量、H2O2投加量和光照时间等因素对造纸废水的COD去除率的影响。结果表明,造纸废水的COD去除率达到95%以上,pH值6·82,造纸废水的各项指标达到了排放标准。     

Phen—NH_4F体系测定植物样品中铁价态的研究

本文建立的以phen—NH_4F体系准确测定植物性样品中铁价态的新方法,有效地阻止了在柠檬酸等植物性样品中的有机酸存在下的由Fe~(3+)—Phen络合物向Fe~(2+)—phen还原的散射光还原反应的发生,同时高倍量的Ca~(2+)、Mg~(2+)、qb~(2+)、Zn~(2+)等离子的存在对测定结果无干扰.该方法的回收率在99.5%以上.