核电站气载放射性流出物环境辐射剂量计算

计算大亚湾核电站正常工况下气载放射性流出物对80km的大气环境防护距离内的公众所致辐射剂量。根据大亚湾核电站2001年气载放射性流出物排放量,逐时观测气象数据及相关参数,选用修正的高斯烟羽模型和美国核管会导则1.109的食物链模型,运用美国橡树岭国家实验室编制的AIRDOS-EPA程序,程序经修改后适合于中国核设施的计算。计算得到2001年大亚湾核电站气态放射性流出物对周边80km范围内的公众所致的年均集体剂量为4.722E-3人·希,最大个人有效剂量为1.362E-8希。结果表明,2001年大亚湾核电站正常工况下,气载放射性流出物对周围公众造成的剂量当量远低于国家标准,对周边地区居民健康几乎没有影响。     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

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。     

Molecular modeling in environmental science∗

Quantum mechanic computer models are often used in chemistry to predict properties of molecules and to simulate reaction pathways. Such models calculate bond lengths, bond angles, dihedral angles, the energy of the molecular‐orbitals (MO's), the dipole moment, the ionisation potential, and the heat of formation. These results lead to detailed information on electronic structures like bond orders, electronic charges and levels of frontier orbitals (HOMO, LUMO).

It is possible to calculate properties of ground state molecules as well as ionic and radicalic structures, or reaction intermediates and other compounds with very short lifetimes.

From the exact knowledge of electronic structure, frontier orbitals, and reaction intermediates it is possible to predict stability of chemicals in the environment but also of fictive chemicals, which are not yet synthesized. Some authors have shown that there are correlations between electronic structure and toxicity.

The most interesting models for environmental chemistry are semiempirical models, such as MINDO, MNDO or MOPAC. Theses programs are able to handle molecules with 30 and more heavy atoms (all elements without hydrogen), and it is possible to install them on main frame computers (CPU‐time several minutes to hours) and on personal computers, with coprocessors (CPU‐time several hours to a few days).

Normally the molecule is read in from a Z‐matrix (a matrix of polar coordinates of atoms connected in the molecule) and with symmetry data. Furthermore, programs are available which create a Z‐matrix from the molecular structure plotted on the screen with a mouse.     

3种助剂对赤子爱胜蚓的急性毒性

为了探究新型助剂LD-10与常用助剂NP-10、NP-4对土壤非靶标生物的影响,以赤子爱胜蚓(Eisenia fetida)为受试生物,采用自然土壤法和灭菌土壤法,研究了这3种助剂对土壤蚯蚓的急性毒性.结果表明,在自然土壤中LD-10、NP-10和NP-4对蚯蚓7d半致死浓度w(LC50)分别为482.58、1 077.50和343.17 mg·kg-1,14 d的w(LC50)分别为438.38、984.64和316.65 mg.kg-1.在灭菌土壤中LD-10、NP-10和NP-4对蚯蚓7d的w(LC50)分别为350.71、960.95和309.63 mg·kg-1,14d的w(LC50)分别为320.24、745.99和274.76 mg·kg-1.在自然土壤和灭菌土壤中3种助剂对赤子爱胜蚓均为低毒,毒性由大到小依次为NP-4、LD-10和NP-10,且3者在灭菌土壤中的毒性均明显高于自然土壤.     

苯并[a]芘对马氏珠母贝D型面盘幼虫发育的影响

苯并芘(B[a]P)已广泛分布于海洋环境中,低等海洋无脊椎动物从受精卵开始整个生长发育过程都面临着B[a]P等多环芳烃类污染物(PAHs)的威胁。本实验以热带海洋优势贝类马氏珠母贝(Pinctada maetensii)作为材料,研究B[a]P对马氏珠母贝D型面盘幼虫发育的影响。将幼虫暴露于不同浓度(1、2、4、10和15μg·L-1)B[a]P中,在暴露后第12、24、36、48、72、84小时,分别测定其D型面盘幼虫的死亡率和畸形数。结果表明:B[a]P对D型面盘幼虫死亡率的影响明显,死亡率与时间呈正相关,其中4和10μg·L-1浓度组的响应最敏感。在1～10μg·L-1浓度范围内,死亡率与浓度呈正相关;B[a]P暴露对马氏珠母贝D型面盘幼虫的形态也有显著影响,且随着浓度的增大产生畸形个体的时间越短。另外,B[a]P对马氏珠母贝D型面盘幼虫的半数致死浓度(LC50)随着时间的推移逐渐降低后趋于稳定,48h时LC50趋于稳定,为21.56μg·L-1。研究表明,B[a]P对马氏珠母贝D形幼虫的发育具有不利影响,并可能影响其种群结构。     

利用神经网络法对胺类有机物急性毒性的分类及定量预测

运用三层误差反向传播网络对５１种胺类有机物进行了结构－毒性关系的研究,进入的结构参数为分子连接性指数信息理论指及分子量等６种均可通过分子拓扑图直接计算获得的指标。毒性参数选用大鼠经口ＬＤ５０,根据其大小将样本分为３类：高毒,中毒,低毒,在神经网络模型上作出差别归类,并分别对每类进行定量预测。     

Toxicity Testing of Leachate from Waste Landfills Using Medaka (Oryzias Latipes) for Monitoring Environmental Safety

To investigate the environmental safety of waste disposal landfill sites and of land reclaimed from such sites, we evaluated the toxicity of leachate from these sites by a combination of bioassays in the Japanese killifish medaka Oryzias latipes. We tested for lethal toxicity in adult and larval medaka and for hatching inhibition of embryos from eggs. As biochemical evidence of the effects of leachate exposure, CYP1A (EROD activity) and vitellogenin (Vtg) were induced. We also bioassayed water-treated leachate and downstream river water. Leachate solution was lethal to larval and adult medaka. Embryo hatchability was inhibited, and abnormal hatching, spinal deformity and anisophthalmia occurred in embryos exposed to leachate solution. CYP1A was induced by exposure to leachate solution diluted to 1.0%, and EROD activity was significantly higher than in control. Vtg and unknown proteins were induced in the sera of male medaka exposed to the diluted leachate solution. Conventional water treatments worked effectively to remove toxic compounds but did not work well to remove element ions, including heavy metals. Treated leachate produced neither lethal toxicity nor hatching abnormalities during the exposure period. Fish toxicity tests for leachate would be useful for monitoring the environmental safety of landfill sites.     

Assessment of indoor radiation level in the environs of the uranium deposit area of West Khasi Hills District,Meghalaya, India

An estimation of the indoor background radiation dose distribution was carried out in dwellings of eleven villages located within and around the uranium mineralization area of Kylleng-Pyndensohiong, Mawthabah in West Khasi Hills District of Meghalaya, India. The ambient indoor gamma radiation level was monitored using Thermo Luminescence Dosimeters (TLDs) while the indoor radon and thoron concentration was measured using twin-cup dosimeters employing Solid State Nuclear Track Detectors (SSNTDs). Results obtained from the study reveals that the local inhabitants of villages located close to the mining site receive higher doses than those inhabitants of villages located at a much farther distance from the mining site. The average total annual effective dose was found to be varying from 1.2 mSv y⁻¹ in the village of Langpa to 3.4 mSv y⁻¹ in the village of Nongbah Jynrin. The data obtained will serve as a reference in documenting changes to environmental radioactivity if mining is to be carried out in the future.