不同基因型杨树的光合特征与臭氧剂量的响应关系

采用开顶式气室装置研究不同臭氧浓度对3种基因型杨树(‘546’、‘90’和‘84K’)光合作用特征的影响.结果表明,随着O_3浓度的升高,净光合速率(P_n)、蒸腾速率(T_r)、水分利用效率(WUE)、电子传递速率(ETR)、PSⅡ反应中心激发能捕获效率(F'_v/F'_m)、光化学猝灭系数(q P)、PSⅡ实际光化学量子效率(Phi PS2)、叶绿素a(Chla)、叶绿素b(Chlb)、叶绿素总量(Chla+b)和类胡萝卜素(Car)均显著降低,胞间CO_2浓度(c_i)显著升高,气孔导度(G_s)变化不显著.不同基因型杨树各项光合生理指标之间均存在显著性差异,基因型‘546’各项光合指标(除G_s外)与O_3剂量(AOT40,小时O_3浓度大于40nmol·mol~(-1)的累计值)间具有显著的线性相关关系(P0.01),并且光合色素含量随着O_3浓度的升高而显著降低.但高浓度O_3对基因型‘90’和‘84K’光合色素影响不显著.从多数光合特征指标特别是叶绿素总量的O_3剂量线性响应关系来看,基因型‘546’表现出最大的斜率,基因型‘90’次之,基因型‘84K’斜率最小,因而可得知随着O_3浓度升高,三者的臭氧敏感性为‘546’‘90’‘84K’.该研究结果为O_3污染环境下杨树基因型筛选与培育,以及保护杨树免受O_3伤害提供科学依据.     

比较2种RAD54启动子调控的全酵母发光细胞对化学诱变原的评价效果

通过分子生物学技术构建2种不同RAD54启动子调控的yEGFP重组报告载体pRAD54￣yEGFP和pRAD54S￣yEGFP,前者启动子DNA为1.8 kb,后者为0.5 kb,分别转入W303￣1A酵母细胞,构建2种启动子调控的发光酵母细胞,用不同化学诱变原作用后,用流式细胞仪和多功能发光仪测定酵母的发光强度。结果发现2种启动子调控的酵母细胞的发光强度均与化学诱变原(甲磺酸甲脂、4￣硝基￣N￣氧化喹啉和5￣氟尿嘧啶)有明显的剂量效应关系,但是W303￣1A/RAD54￣yEGFP剂量效应关系较为明显,产生的最大诱导倍数(5.96、2.19和2.71)明显高于W303￣1A/RAD54S￣yEGFP所产生的最大诱导倍数(2.53、1.50和1.91),可能与启动子序列中转录因子的数量以及转录因子间协同增效作用有关。同时发现,流式细胞仪测定效果明显优于发光仪测定效果。所以在构建RAD54启动子调控重组酵母细胞筛选诱变时,选用全启动子序列效果较好。     

部分除草剂与重金属混合物对发光菌的毒性

以5种不同类型除草剂和4种重金属为混合物组分,探索混合物毒性变化规律.应用微板毒性分析方法,测定了百草敌、磺草灵、西草净、除草定、环嗪酮、CdCl2·2.5H2O、Ni(NO3)2·6H2O、CoSO4·7H2O和ZnSO4·7H2O对淡水发光菌—青海弧菌Q67(Vibrio qinghaiensis sp.—Q67)的发光抑制毒性.应用非线性最小二乘拟合技术模拟实验剂量-效应数据.结果表明,5种除草剂与4种重金属化合物的剂量-效应曲线(DRC)均可用Weibull函数有效表征.为了全面考察各种不同浓度组成的混合物对Q67的毒性,设计了9个组分同时存在的3个等效应浓度比(EECR)混合物和10个均匀设计浓度比(UDCR)混合物.同样应用微板毒性分析方法测定了各个混合物对Q67的抑制毒性,并应用非线性最小二乘拟合技术模拟了其剂量-效应曲线.通过剂量加和(DA)与独立作用(IA)模型综合分析了各个混合物对发光菌的毒性变化规律.结果表明,不同类型除草剂与多种重金属的各种浓度组合的混合物毒性均可用DA模型进行预测和评估.     

活性污泥胞外聚合物提取方法优化

试验对比了不同离子交换树脂(CER)含量和pH条件下胞外聚合物(EPS)的提取效果差异。结果表明,EPS各组分提取浓度均随离子交换树脂用量增加而增加,但各组分趋势不同。TOC的最佳树脂剂量为100 g CER/g VSS,而蛋白质、多糖和DNA的最佳树脂剂量约为70 g CER/g VSS。pH值对TOC、DNA和多糖的提取浓度影响较小,但对蛋白质影响比较大。各提取条件下,EPS各组分提取浓度随时间的变化过程可以分为平稳增长期、快速增长期及稳定期。     

Uranium isotopes in Tunisian bottled mineral waters

²³⁴U and ²³⁸U activity concentrations and their relative effective doses have been determined in 10 bottled mineral waters in Tunisia. Alpha spectrometry was used as technique to measure uranium isotopes. The obtained isotopic ratio ²³⁴U/²³⁸U varies between 1.1 and 3 which means that the two isotopes are not in radioactive equilibrium. Measured activity concentration varies between 3.2 and 40 mBq/l for ²³⁴U and between 1.5 and 26.3 mBq/l for ²³⁸U. Effective doses (assuming 2 litres per day of water consumption) coming from this two isotopes are found to vary between 0.16 and 2.02 μSv/a which is lower than the maximum recommended dose level by the WHO.     

Validation of I ecological transfer models and thyroid dose assessments using Chernobyl fallout data from the Plavsk district, Russia

Within the project “Environmental Modelling for Radiation Safety” (EMRAS) organized by the IAEA in 2003 experimental data of ¹³¹I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of ¹³⁷Cs soil contamination in all the settlements and ¹³¹I/¹³⁷Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of ¹³¹I content in thyroid of townspeople and villagers, and 90 measurements of ¹³¹I concentration in milk were used for validation of the model predictions.A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten.     

Tissue radionuclide concentrations in water birds and upland birds on the Hanford Site (USA) from 1971-2009

Historical operations at the Hanford Site (Washington State, USA) have released a wide array of non-radionuclide and radionuclide contaminants into the environment. As a result, there is a need to characterize contaminant effects on site biota. Within this framework, the main purpose of our study was to evaluate radionuclide concentrations in bird tissue, obtained from the Hanford Environmental Information System (HEIS). The database was sorted by avian group (water bird vs. upland bird), radionuclide (over 20 analytes), tissue (muscle, bone, liver), location (onsite vs. offsite), and time period (1971-1990 vs. 1991-2009). Onsite median concentrations in water birds were significantly higher (Bonferroni P < 0.05) than those in onsite upland birds for Cs-137 in muscle (1971-1990) and Sr-90 in bone (1991-2009), perhaps due to behavioral, habitat, or trophic species differences. Onsite median concentrations in water birds were higher (borderline significance with Bonferroni P = 0.05) than those in offsite birds for Cs-137 in muscle (1971-1990). Onsite median concentrations in the earlier time period were significantly higher (Bonferroni P < 0.05) than those in the later time period for Co-60, Cs-137, Eu-152, and Sr-90 in water bird muscle and for Cs-137 in upland bird muscle tissue. Median concentrations of Sr-90 in bone were significantly higher (Bonferroni P < 0.05) than those in muscle for both avian groups and both locations. Over the time period, 1971-2009, onsite median internal dose was estimated for each radionuclide in water bird and upland bird tissues. However, a meaningful dose comparison between bird groups was not possible, due to a dissimilar radionuclide inventory, mismatch of time periods for input radionuclides, and lack of an external dose estimate. Despite these limitations, our results contribute toward ongoing efforts to characterize ecological risk at the Hanford Site.     

Low dose effects and non-monotonic dose responses for endocrine active chemicals: Science to practice workshop: Workshop summary

A workshop was held in Berlin September 12–14th 2012 to assess the state of the science of the data supporting low dose effects and non-monotonic dose responses (“low dose hypothesis”) for chemicals with endocrine activity (endocrine disrupting chemicals or EDCs). This workshop consisted of lectures to present the current state of the science of EDC action and also the risk assessment process. These lectures were followed by breakout sessions to integrate scientists from various backgrounds to discuss in an open and unbiased manner the data supporting the “low dose hypothesis”. While no consensus was reached the robust discussions were helpful to inform both basic scientists and risk assessors on all the issues. There were a number of important ideas developed to help continue the discussion and improve communication over the next few years.     

Radionuclide content of building materials and associated gamma dose rates in Egyptian dwellings

Studies have been carried out to determine the natural radioactivity in some building materials (bricks, tiles, marble and ceramics) and their associated radiation hazard. The radioactivity concentrations of ²²⁶Ra ²³²Th and ⁴⁰K were measured using a gamma spectrometer with a Hp–Ge detector. The activities of ²³⁸U and ²³⁴U were measured using an alpha-spectrometer with a surface barrier detector after applying a radiochemical procedure. The ²³⁴U/²³⁸U isotopic ratios were calculated. The radium equivalent activities and the radiation hazard index associated with the natural radionuclides were calculated. A computer program was developed and applied to calculate the dose rate a person will receive from the walls of a room constructed from the studied building materials.     

室内尘埃中铅的赋存形态与儿童血铅的相关性研究

有关室内尘埃中铅的赋存形态与儿童血铅的相关性研究尚未见报道。在对某地儿童血铅进行调查期间,发现当地儿童血铅浓度与室内尘埃中铅的水溶态、离子交换态、腐殖酸结合态、铁锰氧化态、强有机结合态和残渣态呈正相关,但不显著,无统计学意义。但与总铅浓度呈显著正相关(R=0.447,P=0.032),与铅的碳酸盐结合态呈高显著相关(R=0.537,P=0.008)。在此基础上,将儿童血铅分别与尘埃中铅暴露量、摄入量和潜在剂量进行相关分析,结果表明,儿童血铅与室内尘总铅摄入量和总铅潜在剂量正相关但无统计意义,与尘总铅暴露量显著相关(R=0.431,P=0.040),与碳酸盐态的暴露量(R=0.537,P=0.008)、摄入量(R=0.538,P=0.008)和潜在剂量(R=0.540,P=0.008)高度显著相关。提示在土壤和尘埃中铅的碳酸盐态含量较高的地区,碳酸盐态铅可能是造成儿童血铅超标的主要原因。