Probing and understanding interaction of Eu(III) with γ- alumina in presenceof malonic acid

Radionuclide migration in aquatic environment is influenced by its sorption onto colloids/mineral oxides and the presence of organic complexing anions. With a view to understand the sorption of trivalent actinides by mineral oxides in presence of organic acid, in the present study, Eu(III), malonic acid (MA) and γ-alumina are considered as representatives of trivalent actinides, low molecular weight natural occurring organic acid and aluminol sites, respectively. The influence of MA on sorption of Eu(III) by γ-alumina was elucidated by batch sorption, spectroscopic techniques and surface complexation modeling, for the first time. Attenuated Total Reflection-Fourier Transform Infrared spectroscopic studies of MA sorbed on γ-alumina revealed the presence of two inner-sphere surface complexes. Batch sorption for binary (alumina-Eu(III)) and ternary (alumina-Eu(III)-MA) systems were investigated as a function of pH, Eu(III) concentration and sequential addition of Eu(III)/MA. The pH edge for Eu(III) sorption shifts to higher pH with increasing Eu(III) concentration. In ternary systems, Eu(III) sorption is significantly enhanced at pH < 4.5. Eu(III) speciation on γ-alumina is independent of addition sequence of Eu(III)/MA. Time resolved fluorescence spectroscopy of Eu(III) sorbed on γ-alumina exhibited two surface species, XOEu²⁺ and (YO)₂Eu⁺. The enhancement in I₆₁₆/I₅₉₂ and lifetime for ternary systems, as compared to binary system, at low pH, indicates the participation of Eu-MA complexes in the formation of surface species in ternary systems. The diffuse layer model has been employed to successfully model the experimental sorption profiles of binary and ternary systems, using code FITEQL 4.0, by considering the surface species identified by spectroscopic techniques.     

溶氧及pH对地衣芽孢杆菌合成聚γ-谷氨酸的影响

在3.7L发酵罐中研究了溶氧、pH和甘油流加对地衣芽孢杆菌分批发酵生产聚γ-谷氨酸(γ-PGA)的影响.结果表明,当葡萄糖浓度为27.9g/L且通气量控制在4L/min时,搅拌转速达到300r/min即可满足细胞生长和聚γ-谷氨酸合成对溶解氧的需求.不同pH控制方式对聚γ-谷氨酸分批发酵的影响有较大差异.不控制pH时,细胞干重和聚γ-谷氨酸产量比控制pH为5.5的发酵分别低26%和94%.研究了将pH控制在4.0、4.5、5.0、5.5、6.0和6.5的聚γ-谷氨酸分批发酵过程,发现在pH5.5时聚γ-谷氨酸总产量最高.以溶氧水平作为甘油代谢指针来控制甘油限制性流加既可维持一定菌体生长,又不会发生发酵液中残余甘油及有害代谢产物阻遏作用.菌体关于甘油的表观的率、聚γ-谷氨酸的平均比生产速率较没有采用甘油限制性流加时都有所提高.图4表1参7     

广东下庄铀矿田土壤的天然放射性研究

用γ能谱分析方法测量了广东下庄铀矿田土壤中放射性核素^>226Ra,^>232Th 和 K 的含量,分别为 111.7(40.2～441.5)Bq/kg,71.5(32.6～4088.1)Bq/kg, 672.1(441.8～912.6)Bq/kg.同全国和广东省的平均值相比,^>226Ra 的含量明显偏高.在此基础上,计算了距地面 1m 高处空气γ辐射吸收剂量率、等效镭浓度和外照射指数,平均值分别为 123.9nGy/h, 265.7Bq/kg, 0.7,表明广东下庄铀矿田的γ辐射外照射水平远高于正常值.应用氡的对流和扩散理论,计算了空气中氡的理论浓度,平均值为 80.2Bq/m³计算结果与实测值基本吻合.     

纳米零价铁对γ-HCH的降解效果及机理研究

采用液相还原法制备纳米零价铁(nZVI),透射电镜表征显示,其粒径<20nm,在介质中处于团簇状态.利用所合成的nZVI对γ-HCH进行了还原脱氯研究,结果表明,nZVI具有很高的表面反应活性,当用量为0.5g/L时,反应90min,对2.5mg/L的γ-HCH去除率达90%以上.nZVI对γ-HCH的去除符合准一级反应动力学方程,其反应速率和去除率与pH值、nZVI添加量、γ-HCH初始浓度、共存离子等因素有关.反应速率随pH值的减小而增大,NO3-对反应速率有较强的抑制作用,Ca2+,Mg2+和SO42-对反应速率影响不大.利用GC-MS检测到降解产物四氯环己烯(TeCCH)和氯苯(CB)的存在,推测反应机制为双氯脱除反应和脱氯化氢反应.     

杭州市大气超细颗粒数浓度谱季节性特征

利用快速迁移率粒径谱仪(fast mobility particle sizer,FMPS)对杭州市大气超细颗粒进行监测,并对杭州市2011～2012年大气超细颗粒物的数浓度、粒径分布的季节变化及其与气象之间的关系进行研究.结果表明,杭州市超细颗粒数浓度呈对数双峰分布,季节变化特征为冬季>夏季>春季>秋季,12月值最高,为3.56×104cm-3,10月最低,为2.51×104cm-3.CMD(count medium diameter)季节变化特征为春>冬>秋>夏,4月最高,为53.51 nm;6月最低,为16.68 nm.气象因素对超细颗粒数浓度有一定影响.     

泉州市环境放射性水平调查

报道了福建省泉州市环境放射性水平调查方法和结果。调查结果表明 :(1)泉州市原野γ辐射剂量率为 72 .3～ 16 5 .1n Gy/ h,按测点和人口加权均值为 111.5 n Gy/ h和 110 .9n Gy/ h,高于福建省的平均值 (分别为 92 .6 n Gy/ h和87.1n Gy/ h) ,是 UNSCEAR1982年报告中给出的世界陆地γ辐射剂量率按人口加权均值 (5 0 n Gy/ h)的 2 .2 2倍。(2 )泉州市道路γ辐射剂量率测值范围为 6 5 .8～ 14 9.5 n Gy/ h,均值 113.7n Gy/ h,略高于福建省均值 10 6 .4 n Gy/ h。 (3)泉州市建筑物室内天然γ辐射剂量率测值范围为 12 8.9～ 2 86 .3n Gy/ h,按测点和人口加权均值分别为 190 .7n Gy/ h和 188.5 n Gy/h。不同建筑材料建筑物室内天然γ辐射剂量率由高到低的顺序依次为花岗石房 >砖与混凝土房 >煤渣砖房 >砖木、土木房。(4)泉州市天然γ辐射、宇宙和线射天然贯穿辐射所致居民人均年有效剂量当量分别为 1.0 5 m Sv、0 .16 m Sv和1.2 1m Sv,全区集体年有效剂量当量分别为 0 .76× 10 4人· Sv,0 .12× 10 4人·Sv,0 .88× 10 4人· Sv。(5 )土壤中 2 2 6 Ra、2 32 Th、4 0 K含量均值分别为 71.3Bq/ kg、6 8.8Bq/ kg、6 8.8Bq/ kg、94 3.7Bq/ kg。(6 )地下水中2 2 6 Ra、U、Th、Rn浓度均值分别为 31.9m Bq/ L、0 .5     

四种拟除虫菊酯类农药的环境雌激素活性研究

将金鱼(Carassius auratus)分别暴露于0.1mg/L甲氰菊酯、氰戊菊酯、溴氰菊酯和0.5mg/L氯氰菊酯21d后,尾静脉取血,离心分离获得血浆,利用Western-blot方法检测金鱼血浆中是否有卵黄原蛋白产生,同时测定金鱼生殖腺指数、γ-谷氨酰转移酶和乳酸脱氢酶活性.结果表明,对照组雄性金鱼血浆中未检测到卵黄原蛋白,4种拟除虫菊酯农药均能诱导雄性金鱼分泌卵黄原蛋白,而且溴氰菊酯和氯氰菊酯明显降低了雄鱼生殖腺指数,4种农药均能够明显抑制精巢γ-谷氨酰转移酶和乳酸脱氢酶活性.由此可见,4种拟除虫菊酯类农药具有潜在的环境雌激素活性和生殖毒性.     

HCB与γ-HCH在辽河沉积物中的缺氧降解动力学

为全面认识多氯有机物在天然水沉积物中的转化行为,利用超声波发生仪萃取沉积物样品,采用气相色谱仪(Ni63-ECD)定量分析,在缺氧条件下,测定了辽河沉积物中六氯苯(HCB)、γ-HCH的微生物降解速率.在单个培养体系中,测定出不外加有机碳源,外加葡萄糖和乙酸钠3种条件下HCB、γ-HCH的缺氧降解符合准一级动力学方程,动力学常数分别为HCB k(不外加有机碳源)=0.0014d-1, k(葡萄糖)= 0.0033d-1, k(乙酸钠)= 0.0052d-1;γ-HCH k(不外加有机碳源)=0.0454d-1, k(葡萄糖)=0.1143d-1, k(乙酸钠)=0.1451d-1.在2种氯代物混合培养体系中,HCB、γ-HCH的降解速率均有所下降.经GC-MS测定,三氯苯、二氯苯分别是HCB、γ-HCH的主要降解产物.     

Analysis of α, β, γ-hexachlorocyclohexanes in water by novel activated carbon fiber-solid phase microextraction coupled with gas chromatography--mass spectrometry

A fast and simple method for determination of α, β,γ-hexachlorocyclohexanes (HCHs) in water using activated carbon fibersolid phase microextraction(ACF-SPME) were studied. Results showed the performance of adsorption and desorption of three HCHs on ACF were excellent. A wide linear range from 10 to 100 μg/L and detection limits of the ng/L level were obtained using ACF-SPME with GC-MS in selected ion monitoring(SIM) acquisition mode. The proposed method was also successfully applied for determination of three HCHs in tap water. Compared to commercial fibers, ACF showed some advantages such as better resistance to solvents, higher thermal stability, longer lifetime and lower cost. The data demonstrated that GC-MS with ACF-SPME is well suitable for the analysis of HCHs in water.