浅谈TOC与CODCr的关系

介绍了TOC和CODCr的含义,比较了TOC与CODCr测定方法、使用仪器的不同和各自的优缺点,并从理论上和实际水样测定中论述了TOC和CODCr的相关性。对于不同的废水,TOC 与CODCr的相关性不一样,必须先实验求出二者之间的关系。     

固相微萃取-气相色谱法测定水源地水中SVOC

采用固相微萃取-毛细管柱电子捕获气相色谱法测定水源地水中18种半挥发性有机物,优化了萃取纤维、时间、温度、pH值、转子转速、离子强度等萃取条件。方法线性良好,18种化合物的检出限为0.000 2μg/L~0.1μg/L,实际水样加标回收率为84.3%~109%。     

pH值、硫酸根和温度对钢管管垢中铬释放的影响

以市政供水管网钢管管垢为研究对象,将垢层由外向内分为表层、硬壳层和疏松多孔层.利用SEM、BET、XRD、XPS和分形态提取等技术对预吸附Cr(Ⅵ)前后的各层管垢进行表征和分析,并探究了pH值、SO₄^2-浓度和温度对各层管垢中Cr释放的影响.结果显示,钢管各层管垢的主要成分均为α-FeOOH,吸附性能排序为表层>疏松多孔层>硬壳层,管垢中铁元素大多以三价和二价形式存在,具有一定还原性.Cr(Ⅵ)通过物理和化学吸附富集于管垢,主要以铁锰氧化物结合态存在,表层管垢富集量最大.酸性环境、SO₄^2-浓度和温度的升高均会促进Cr的释放.强酸性条件下表层Cr释放浓度为中性条件下的2.76倍;SO₄^2-浓度增加使各层管垢的Cr释放量增加0.1～0.4倍;温度升高20℃,表层管垢的Cr释放量增加26.74%.     

Genotoxicity of chromium in vitro on yeast: Interaction with DNA†

The genotoxicity of chromium chloride was investigated in cells of D₇ strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase.

A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer.

The experiments with ⁵¹Cr radiotracer demonstrated that Cr³⁺ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl₃ that cause some damages to cytoplasmatic membrane.     

Bioremediation of Chromate by Sulfate-Reducing Bacteria, Cytochromes c3 and hydrogenases

The treatment of soils and ground waters polluted by heavy metals is of economical and environmental interest. Reduction of Cr(VI) to the less toxic Cr(III) associated to its precipitation is a potentially useful process for bioremediation. In order to develop ecological processes using micro-organisms, we have compared various sulfate-reducing bacteria for enzymatic reduction of chromate. The best Cr(VI) reductase activity was obtained with Desulfomicrobium norvegicum. Despite morphological changes induced by the presence of chromate, this strain can grow in the presence of up to 500 M Cr(VI) and can decontaminate waters polluted by Cr(VI) when seeded in bioreactors. We have demonstrated the ability of several metalloenzymes (cytochromes c ₃ and hydrogenases) to reduce chromate. Biophysical investigations of the chromate/protein interaction in order to get further informations on the mechanism of metal reduction by cytochromes c ₃ are under the way.     

草酸对Cr胁迫下李氏禾解毒性能的影响

结合因子分析方法分析了草酸对Cr胁迫下李氏禾解毒性能的影响。研究过氧化氢酶(CAT)、可溶性糖、生长指标的变化情况,并运用因子分析方法筛选出最能表征李氏禾生长特性的指标,进而较科学的研究外源草酸对Cr胁迫下李氏禾解毒性能的影响。Cr质量浓度为0、200、400 mg/kg的土壤中,适当浓度草酸对李氏禾CAT影响表现出极显著差异(P0.01);当土壤中Cr质量浓度200 mg/kg,草酸质量浓度为80、120 mg/kg时,可溶性糖浓度分别比本组对照降低了23.59%、32.65%;株高可作为关键因子的关键变量。外源草酸可以增强李氏禾对Cr的解毒性能且与草酸浓度有关,因子分析方法可以应用于李氏禾研究中。     

Oxidation of Cr(III) on birnessite surfaces: The effect of goethite and kaolinite

Oxidation of Cr(III) by manganese oxides may pose a potential threat to environments due to the formation of toxic Cr(VI) species. At present, it was still unclear whether the extent of Cr(III) oxidation and fate of Cr(VI) would be changed when manganese oxides co-exist with other minerals, the case commonly occurring in soils. This study investigated the influence of goethite and kaolinite on Cr(III) oxidation by birnessite under acidic pH condition (pH 3.5) and background electrolyte of 0.01 mol/L NaCl. Goethite was found not to affect Cr(III) oxidation, which was interpreted as the result of overwhelming adsorption of cationic Cr(III) onto the negatively-charged birnessite (point of zero charge (PZC) < 3.0) rather than the positively-charged goethite (PZC = 8.8). However, more Cr(VI) would be retained by the surface with the increase in addition of goethite because of its strong ability on adsorption of Cr(VI) at low pH. Moreover, either Cr(III) oxidation or distribution of the generated Cr(VI) between the solid and solution phases was not affected by kaolinite (PZC < 3.0), indicating its low affinity for Cr species. Reactions occurring in the present mixed systems were suggested, which could be partly representative of those in the soils and further indicates that the mobility and risk of Cr(VI) would be decreased if goethite was present.     

基于环境一号卫星的四川盆地气溶胶光学厚度精细化反演

四川盆地为中国灰霾形势较为严重的区域之一,对四川盆地大气灰霾的监测具有十分重要的意义。利用环境一号卫星数据,对能表征大气污染程度的气溶胶光学厚度进行了反演。提出了用EVI植被指数判定暗像元精细化反演气溶胶光学厚度的方法,该方法能较好地去除部分大气影响,气溶胶光学厚度反演结果与CE318的气溶胶光学厚度结果相关性较高,误差较小,具有较高的精度,反演结果满足精细化要求。反演结果表明,四川盆地内有德阳、成都、眉山和乐山4个气溶胶光学厚度高值区,该高值区呈带状分布且与四川盆地的地形密切相关。     

基于层次分析法的南疆旅游纪念品价值评价

南疆地处新疆天山以南,旅游纪念品资源丰富,有鲜明的地方特色和独特的民族风格,但现有旅游纪念品开发深度不够,影响了游客旅游质量.利用层次分析法（AHP）对南疆旅游纪念品资源价值、商品属性和市场潜力进行评价,认为资源价值在旅游纪念品评价中权重最高,商品属性和市场潜力是影响纪念品价值的重要因素,并针对评价体系和综合评价结果对南疆旅游纪念品进行价值分析.     

Adsorption characteristics and mechanism of Cr （Ⅵ） on chitoan-yttrium porous microsphere

以壳聚糖和Y2（OH）5NO3为原料通过乳液交联法制备了壳聚糖-钇（Ch—Y）复合微球,通过扫描电镜、透射电镜、X射线衍射、红外光谱等方法对其表面形貌、结构进行了表征.探讨了溶液的pH值、反应时间、投加量、离子初始浓度对其吸附性能的影响.研究结果表明,壳聚糖-钇（Ch—Y）复合微球在pH值为3的酸性环境中对Cr（Ⅵ）保持了较高的吸附能力,吸附容量为52.39mg·g-1,其吸附行为符合Langmuir吸附等温模型;通过吸附机理的研究,发现壳聚糖-钇（Ch—Y）对Cr（Ⅵ）吸附是化学吸附静电吸附协同氧化Cr（Ⅵ）离子作用来实现的.