氧化还原介体调控亚硝酸盐反硝化特性研究

采用实验室驯化的亚硝酸盐反硝化菌群作为菌种,优化亚硝酸盐降解条件,探究在氧化还原介体蒽醌-2-磺酸钠(AQS)存在条件下亚硝酸盐反硝化的特性.结果表明,反硝化菌群降解亚硝酸盐的最适条件为:温度35℃,pH为8,丁二酸钠为碳源,碳氮比4∶1,初始亚硝酸盐浓度100 mg.L-1;AQS的最佳投加量为0.16 mmol.L-1,介体调控的反硝化体系氧化还原电位略有降低,维持在-400～-500 mV之间,pH随亚硝酸盐降解速率增加而增大,最终稳定到9～10之间;通过分析反硝化中间代谢产物,推测AQS在亚硝酸盐反硝化过程中不仅起到辅酶CoQ的作用而且加速了细胞色素传递电子的全过程.本研究可为氧化还原介体调控亚硝酸盐反硝化实际应用提供理论基础和优化参数.     

北天堂垃圾污染场地氧化还原分带及污染物自然衰减研究

通过对北京市北天堂垃圾填埋场周围实际监测数据资料的分析,研究了垃圾填埋污染场地的氧化还原分带和污染物的自然衰减作用.结果表明,北天堂垃圾填埋污染场地存在氧化还原分带现象,依据各氧化还原带标志性物质浓度的分布规律和特点划分了5个氧化还原带,即产甲烷带、硫酸盐还原带、铁还原带、硝酸盐还原带和氧还原带.不同有机污染物在不同的氧化还原带中的衰减不同;挥发酚和氰化物在硫酸盐还原带中的含量相对较高,分别为0.005和0.019 μg/L;Cr、Pb、Ni、As、Cu、Cd、Zn和Mn等重金属在产甲烷带中的含量相对较高,分别为25.11、 33.82、 29.93、 3.18、 2.3、 0.1、 283.1、 1 220　μg/L.因此,氧化还原带对污染物的衰减起重要作用.     

水溶性有机物的电子穿梭功能研究

以源于污泥的DOM(dissolved organic matter)为供试材料,以中国希瓦氏菌(Shewanella cinica)D14T为电子转移驱动力,研究了DOM的氧化还原性能与电子穿梭功能.结果表明,污泥DOM可作为末端电子受体接受醌还原菌D14T呼吸链上的电子,从而转变为还原态DOM,而还原态DOM可将电子再次转移给Fe(Ⅲ).经D14T还原后,DOM电子供给量(e-/C)由初始2.2~14μmol.g-1增加到253~347μmol.g-1.循环伏安法与多次还原-氧化循环实验表明,DOM呈现2对明显的氧化还原峰,经3次还原-氧化循环后电子供给量可稳定维持在150~250μmol.g-1之间,说明DOM具有重复利用、反复转移电子的特性.在菌株D14T还原水铁矿的体系中,加入DOM可提高水铁矿的还原溶解速率,其原因是DOM在D14T与水铁矿之间充当了电子穿梭体的角色.这些结果反映了DOM在电子转移反应中的重要性,为DOM的环境属性提出了一个新见解.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

Iron-catalyzed oxidation of s(IV) species by oxygen in aqueous solution: Influence of pH on the redox cycling of iron

Redox cycling of Fe(II)/Fe(III) during the catalyzed aqueous S(IV) oxidation by dissolved oxygen in the presence of Fe(II) and/or Fe(III) at an initial pH_i of 4.4, often observed in atmospheric waters, was studied in detail. It has been found that the reaction rate is not considerably affected by the oxidation state of iron at the start of the reaction. An equilibrium between Fe(II) and Fe(III) was established a few minutes after the start of the reaction, regardless of the oxidation state of iron at the beginning of the experiment. The prevailing oxidation state of iron in a particular phase of the reaction depends on the concentration of S(IV) in the reaction solution. It has been found that the formation of polymerized hydroxo Fe(III) species is also included in the mechanism of the Fe-catalyzed oxidation of S(IV). The formation of these species was confirmed by the on-line measurement of Fe(II) and Fe_reac. The results also clearly demonstrate that the pH_i of the solution is a major factor, controlling the concentration of Fe(III) ions, the form of S(IV) species, and consequently the reaction rate of S(IV) oxidation by oxygen.     

Sediment Parameters of Northwest Black Sea Shelf and Slope: Implications for Transport of Heavy Metals and Radionuclides

In June 1990, sediment cores were obtained from several locations in the Northwest Black Sea shelf and slope by a joint US/USSR scientific team aboard the survey vessel R/V VODYANITSKY. the goal of this investigation was to determine the distribution and levels of radioactivity resulting from the Chernobyl 1986 nuclear accident. the sediment was characterized for texture, mineral composition, redox state, heavy metals, and radionuclides. Correlations emerging from these data reveal paths of dispersal and transport of materials from river sources to deposition sites on the shelf and slope. Kaolinite in the clay mineral suite clearly reflects a dispersal pattern originating in the Danube River and progressing in an easterly direction across the shelf. Sand-size gypsum and the elemental heavy metals Zn, Cu, Cr, and Pb (probable industrial source) as well as the elements Al and Mg (probable terrigenous source) also show a dispersal pattern from the Danube station location in an easterly direction across the shelf. the dispersal direction indicated by these materials is not in conflict with recent existing notions concerning the hydrology of the Northwest Black Sea. Barium anomalies at a midshelf location may be related to operations in the Lebada oil fields situated updrift. Heavy mineral dispersal reflect the Danube and -Crimean Provinces established for the shelf and relate to terrestrial source areas. in addition, the heavy mineral monazite correlates with the radioactive Th 232 found most abundantly in the Crimean Province. Local anomalies of Mn, Fe and U in the sediment at station locations are related to redox (Eh) conditions and other factors. Cs^134/137 data, reported by Curtis and Broadway (1991), correspond to transport and dispersal patterns implicit in the mineralogic, anthropogenic indicators, and sediment characteristics of the study area.     

淹水土壤中Se(Ⅵ)还原反应的机理及条件

通过红黄泥和紫潮泥两种土壤淹水培养和硒的价态测定结果表明：在450mV培养下，外加Se（Ⅵ）第1天有57．2％仍保持Se（Ⅵ)，23.4％还原为有机Se，培养过程中Se(Ⅵ）呈稳定态，有机Se则氧化成Se(Ⅵ），反应为准一级动力学方程；在175mV培养下，外加Se(Ⅵ）第1天有81．8％还原为有机Se,8.9％还原为有机Se,8.9％为Se(Ⅵ），培养过程中有机Se呈稳定态，Se(Ⅵ）则还原为Se(Ⅵ），反应符合动力学一级方程。土壤中Se(Ⅵ）／Se(Ⅳ）体系氧化还原反应的临界电位为71．4mV-206.1mV(pH7.0)，土壤pH上升1个单位，电位相应降低40．1mV.Se(Ⅵ)/Se(Ⅳ）体系在土壤氧化还原顺序中的反应次序居猛体系之后，与铁体系平行。     

嘉兴市污水海洋处置工程近区稀释度变化研究

针对嘉兴市污水海洋处置工程拟选的场前 0 0 0 0和场前 0 14 0 0两个排放口 ,对一个潮位过程中污水近区初始稀释度的变化进行了物理模型试验研究 ,以国家二类海水水质标准 (GB 30 97 82 )作为控制依据 ,根据稀释度变化过程线计算出了 2 4h内可以满足二类海水水质标准的时间。试验结果表明 ,场前 0 14 0 0排放口处的近区稀释扩散效果最好。     

碱渣海洋倾倒定点化学追踪试验

碱渣海洋倾倒，在夏季温度、盐度和密度跃层存在下，以ｐＨ、浊度为化学追踪指示值，于北黄海５号倾废区进行的三个航次定点化学追踪试验，讨论了碱渣入海后的沉降速度，扩散时间和飘移距离。选择ｐＨ、浊度值作为碱渣海洋倾倒化学追踪指示值是一种尝试。实验室模拟及海上现场试验结果表明，它们在碱渣海洋倾倒中定量描述碱渣在海水中的时空分布是可行的。可作为研究碱渣海洋倾倒区划分合理性应用，并可提供基本依据。     

三亚市区城市污水海洋处置研究

三亚市城市污水原计划二级污水处理厂处理后排入三亚河和榆林内港。经过反复论证，在详细分析计算三亚河、榆林内港水环境容量及自净能力的基础上，研究比较了不同的排放水域、排放方式、污水处理厂数目和处理程度等２２ 个方案后推荐采用污水海洋处置，岸上一级处理（ 预留场地以后再提高处理程度） 后离岸深水排放。现污水海洋处置工程已完成可行性研究和环境影响评价，并正在分阶段设计施工中