沿海城市降水中总汞及汞同位素特征研究

大气汞沉降是汞从排放源进入地表系统最主要的迁移途径,利用汞同位素追踪汞在大气中的迁移转化规律及潜在来源对研究汞的生物地球化学循环具有重要意义.本研究于2012—2013年对厦门市小坪、坂头、鼓浪屿和洪文站点降水中总汞(THg)浓度和汞同位素的变化特征进行了研究.结果表明,厦门降水中THg浓度为1.0～59.4 ng·L~(-1),大气THg湿沉降量为13.1μg·m~(-2)·a~(-1).厦门冷、暖季降水中THg浓度相当,但由于暖季丰沛的降水量,导致暖季THg的湿沉降量约为冷季的2.5倍.降水样品中均表现出负的偶数汞同位素质量分馏(δ~(202)Hg,-2.2‰～-1.5‰)、正的奇数汞同位素非质量分馏(Δ~(199)Hg,0.08‰～0.22‰),以及轻微偏正的偶数汞同位素非质量分馏(Δ~(200)Hg,0.01‰～0.07‰).厦门降水中奇数汞同位素非质量分馏是大气汞液相光致还原反应的结果.偶数汞同位素非质量分馏不明显与其处于较低的纬度有关.厦门降水中δ~(202)Hg接近于厦门当地及贵州燃煤烟气中的δ~(202)Hg值,表明厦门降水中汞可能受到本地或传输过来的燃煤排放的影响.     

Iron and aluminium based adsorption strategies for removing arsenic from water

Arsenic is a commonly occurring toxic metal in natural systems and is the root cause of many diseases and disorders. Occurrence of arsenic contaminated water is reported from several countries all over the world. A great deal of research over recent decades has been motivated by the requirement to lower the concentration of arsenic in drinking water and the need to develop low cost techniques which can be widely applied for arsenic removal from contaminated water. This review briefly presents iron and aluminium based adsorbents for arsenic removal. Studies carried out on oxidation of arsenic(III) to arsenic(V) employing various oxidising agents to facilitate arsenic removal are briefly mentioned. Effects of competing ions, As:Fe ratios, arsenic(V) vs. arsenic(III) removal using ferrihydrite as the adsorbent have been discussed. Recent efforts made for investigating arsenic adsorption on iron hydroxides/oxyhydroxides/oxides such as granular ferric hydroxide, goethite, akaganeite, magnetite and haematite have been reviewed. The adsorption behaviours of activated alumina, gibbsite, bauxite, activated bauxite, layered double hydroxides are discussed. Point-of-use adsorptive remediation methods indicate that Sono Arsenic filter and Kanchan™ Arsenic filter are in operation at various locations of Bangladesh and Nepal. The relative merits and demerits of such filters have been discussed. Evaluation of kits used for at-site arsenic estimation by various researchers also forms a part of this review.     

高效液相色谱-原子荧光光谱联用测定水中形态砷

采用高效液相色谱-氢化物发生-原子荧光光谱联用技术测定水中亚砷酸盐[As(Ⅲ)]、二甲基砷(DMA)、一甲基砷(MMA)和砷酸盐[As(V)]等4种形态砷,以磷酸盐缓冲溶液为流动相,硼氢化钾为还原剂,优化了仪器主要技术参数.As(Ⅲ)、DMA、MMA和As(V)在7 min内实现了良好的基线分离,在5.00 μg/L～...     

Fractionation of Mn, Fe, Zn and Cu in Sediments of Khor Kalabsha, Lake Nasser, Egypt

Khor Kalabsha is the second largest Khor in Lake Nasser, which is a freshwater side-branch of the main lake. Chemical analysis of the samples indicates that calcium carbonate and organic matter content in the surface sediments average 17.8 and 3.07%, respectively. Moreover, manganese, iron, zinc and copper concentrations are lower in Khor Kalabsha than in other lakes of Egypt. It has been found that both oxides and residual forms constitute the major part of the measured elements in the study area, while manganese and iron play an important role in building up clay minerals. It is noted that both zinc and copper fractions are controlled by biological and biochemical processes.     

高原湖泊砷污染健康风险评估

以某高原湖泊为例,以湖水中的砷含量类比推算了从该湖泊取水灌溉区域内水稻和蔬菜的砷含量,对稻米、蔬菜和饮水3种暴露途径进行健康风险评估。结果表明,人群通过摄入区域内稻米、蔬菜的致癌风险系数为可接受的致癌风险,饮用湖水的致癌风险系数为不可接受的致癌风险。     

小球藻对Pb2+吸附及其亚细胞分布研究

通过溶液培养小球藻Pb2+暴露实验分析小球藻对Pb的富集以及亚细胞分布情况.结果表明:小球藻对Pb的富集总量随暴露浓度、暴露时间的增加而增加.运用差速离心法研究了小球藻中Pb在亚细胞中的分布,热力学实验与动力学实验的细胞分布结果均表明含细胞壁等残渣部分(组分I)中Pb的浓度远高于含细胞核、叶绿体、线粒体等细胞器膜系统(组分II)和可溶蛋白等细胞溶质部分(组分III)中Pb的浓度.采用动力学模型与等温线方程对实验数据进行拟合,结果表明小球藻对于Pb2+的生物吸附过程适宜用Elovich方程和二级吸附速率方程采描述,生物吸附平衡可用Langmiur等温式和Freundlich等温式来描述,小球藻对于Pb2+的生物吸附为非均相的扩散过程.     

燃煤砷污染及控制技术研究现状

本文对国内外煤燃烧过程中砷的污染及其控制的研究现状进行了综述。概括了煤燃烧过程中砷的排放对环境产生的危害,分析煤中砷的赋存状态、燃烧过程的转化形态、固砷剂对煤中砷的作用和砷在飞灰中的富集状况,讨论燃前洗煤、燃煤固砷、烟气除尘技术减少煤中砷污染排放的研究现状及可行性;根据洁净煤技术应用现状讨论了动力配煤技术在高砷煤砷污染防治中的积极意义。指出加强对煤中砷的释放、控制理论及实用技术的研究,减少砷污染物排放对环境的污染是今后研究的方向。     

有机氧同位素分馏作用研究进展

植物有机质的氧同位素分馏机制较为复杂,受着多种因素的影响,限制了其在农业、生态学和古环境方面的广泛应用。本文探讨了植物有机质中氧元素的来源、氧同位素分馏机制及影响因素,以期有助于有机氧同位素的应用研究。     

采矿业污染河流底泥及河漫滩沉积物的粒径组成与砷形态分布特征

采用连续提取法分析了刁江底泥和河漫滩沉积物中砷的形态变化规律及其与沉积物粒径组成的关系.结果表明,刁江流域底泥和河漫滩沉积物中As含量分布存在差异,底泥中As主要赋存在63～170μm粒级颗粒中,河漫滩沉积物中As主要赋存在63μm粒级颗粒中.底泥和河漫滩沉积物中砷主要以铁合态、钙合态和残渣态的形式存在,且残渣态比例相对较高,表现出典型的尾砂污染特征.底泥中残渣态砷(Res-As)组成比例总体较高,主要赋存在63～170μm粒级颗粒中,而洪水水位河漫滩沉积物中Res-As组成比例相对较低,这与不同沉积物中硫化态砷的氧化反应差异有关.对于中下游河段,底泥和中水水位河漫滩沉积物中Res-As总体上呈逐渐降低的趋势,铁合态砷(Fe-As)组成比例的分布与Res-As呈相反的趋势.     

污水厂出水DOM的分级及三卤甲烷生成势研究

研究目的在于调查寒冷季节城市污水处理厂出水中天然有机物化学组分分级,探讨各分级组分与消毒副产物生成潜能间之关系。采集污水厂二级出水,以三种不同树脂把污水厂出水中有机物分离成六类不同组分,其中A水厂含量最高的物质为亲水酸性物质(33%)而B水厂的疏水性中性物质含量最多约占总有机物的64%。从总体来看两水厂的疏水性物质含量大于亲水性物质含量,疏水性物质的三卤甲烷生成势也较大,是水体中消毒副产物的主要前驱物质。疏水性有机物质较多,代表受生活污水污染严重,得知该城市污水主要受民生污染较多。