Euro Chlor Risk Assessment for the Marine Environment Osparcom Region: North Sea - Tetrachloroethylene

This risk assessment on tetrachloroethylene (PER) was carried out specifically for the marine environment, according to the methodology laid down in the EU risk assessment Regulation (1488/94) and the Guidance Document of the EU New and Existing Substances Regulation (TGD, 1997). The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by the ratio of the "predicted environmental concentrations" (PEC) and the "predicted no effect concentrations" (PNEC) for the marine aquatic environment. In total, 18 studies for fish, 13 studies for invertebrates and 8 studies for algae have been evaluated. Both acute and chronic toxicity studies have been taken into account and the appropriate assessment factors have been used to define a PNEC value of 51 µg/l. Most of the available monitoring data apply to rivers and estuary waters and were used to calculate PECs. The most recent data (1991-1995) support a typical PEC of 0.2 µg PER/l water and a worst case PEC of 2.5 µg PER/l water. The calculated PEC/PNEC ratios give a safety margin of 20 to 250 between the predicted no effect concentration and the exposure concentration. Additional evaluation of environmental fate and bioaccumulation characteristics showed that no concern is expected for food chain accumulation.     

Assessment of Pesticide Residues in Two Arable Soils from the Semi-Arid and Subtropical Regions of China

The residues of 31 chlorinated hydrocarbons (CHCs), 25 chlorophenols (CPs), 30 organophosphorus (OP) and pyrethroid (PRT) in two arable soils from the semi-arid and subtropical regions of China were assessed. Data obtained indicate that the main compounds of CHC pesticide residues in the semi-arid soil were 4,4′-DDE (25.3 ng/g) and β-HCH (14.1 ng/g), which totally accounted to about 90% of total CHC residues detected. The total content of CHC residues detected in the subtropical soil was only 3.1 ng/g, of which approximately 50% was β-HCH. However, the total content of CP residues in both of the soils was about 11 ng/g. In the semi-arid soil, only parathion-methyl amongst the 30 compounds of OP and PRT residues was detected (32.5 ng/g), whilst malathion and parathion-methyl (8.7 and 17.7 ng/g, respectively) detected in the subtropical soil. Based on these results, it was suggested the environmental risk of pesticide residues ranked in an order as CHCs (mainly as 4,4′-DDE, β-HCH) > OP (parathion-methyl) > CPs for the semi-arid soil, and as OPs (parathion-methyl and malathion) > CPs > CHCs (β-HCH) for the subtropical soil.     

酚类化合物在2-羧基苯甲酰基修饰的超高交联树脂上的吸附

合成了一种用来吸附和去除水溶液中酚类化合物的 2 羧基苯甲酰基修饰的超高交联吸附树脂 (ZH 0 1) ,并从动力学和吸附容量角度比较了XAD 4、AM 1和ZH 0 1分别吸附浓度为 80 0mg/L苯酚的情况。实验结果表明 ,ZH 0 1吸附剂有利于吸附苯酚、对甲苯酚和对硝基苯酚之类的酚类化合物。动力学和热力学研究都得到了相同的结果 :ZH 0 1对苯酚和对甲苯酚吸附是化学吸附的过渡状态 ,而对对硝基苯酚的吸附是一种物理吸附过程 ,并且显示了ZH 0 1表面均孔特性。苯酚在ZH 0 1上的小柱吸附研究表明了吸附穿透容量和总吸附量分别为 2 .38mmol/g和 3.0 5mmol/g ,溶剂甲醇对吸附在ZH 0 1上苯酚的脱附效果较好。     

Stimulation of reductive dechlorination of hexachlorobenzene in soil by inducing the native microbial activity

The reductive dechlorination and behaviour of ¹⁴C-hexachlorobenzene (HCB) was investigated in an arable soil. The activity of the native anaerobic microbial communities could be induced by saturating the soil with water. Under these conditions high rates of dechlorination were observed. After 20 weeks of incubation only 1% of the applied ¹⁴C-HCB could be detected in the fraction of extractable residues. Additional organic substances, like wheat straw and lucerne straw, however considerably delayed and reduced the dechlorination process in the soil. The decline of HCB was not only caused by dechlorination but also by the formation of non-extractable residues, whereby their amounts varied with time depending on the experimental conditions. Several dechlorination products were detected, indicating the following main HCB transformation pathway: HCB → PCB → 1,2,3,5-TeCB → 1,3,5-TCB → 1,3-DCB, with 1,3,5-TCB as main intermediate dechlorination product. The other TeCB-, TCB- and DCB-isomers were also detected in low amounts, showing the presence of more than one dechlorination pathway. Since the methane production rates were lowest when the dechlorination rates were highest, it can be assumed that methanogenic bacteria were not involved in the dechlorination process of HCB. The established ¹⁴C-mass balances show, that with increasing dechlorination and incubation times, the ¹⁴C-recoveries decreased.     

Volatilization and Biodegradation of VOCs in Membrane Bioreactors (MBR)

Volatilization and biodegradation are major competitive volatile organic compound (VOC) removal mechanisms in biological wastewater treatment process, which depend on compound specific properties and system design/operational parameters. In this study, a mathematical model was used to determine major removal pathways at various organic loading rates (OLR), solids residence time (SRT) and dissolved oxygen (DO) concentrations in a biological process for vinyl acetate. Model results showed that biological treatment process should be designed with long SRT, high OLR and low DO concentrations to maximize biodegradation and minimize volatilization of VOCs. Unless a VOC is toxic to microorganisms under the given conditions, low VOC emission rates are an inherent advantage of MBRs, which operate at higher OLR and longer SRT compared to conventional activated sludge process. A lab scale membrane bioreactor (MBR) was operated at varying OLR to investigate the relative volatilization and biodegradation rates for acetaldehyde, butyraldehyde and vinyl acetate. Synthetic wastewater containing three VOCs was introduced to the MBR. The DO concentration and SRT was maintained at 2.0 mg L^{− 1} and 100 days, respectively. The overall VOC removal rate was more than 99.7% for three VOCs at all the OLR. For vinyl acetate, the biodegradation rate increased from 93.87 to 99.40% and the volatilization removal rate decreased from 6.09 to 0.59% as OLR was increased from 1.1 to 2.0 kg COD m^{− 3} d^{− 1}. It was confirmed that a MBR can be a promising solution to reduce VOC emissions from wastewater.     

建筑火灾烟气运动数值模拟方法的回顾与评价

系统地介绍了建筑火灾烟气运动的各种数值模拟方法。将收集到的59种建筑火灾模型分为4大类，包括9种网络模型、32种区域模型、15种场模型及3种复合模型；从理论角度阐述了各类模型的计算方法，着重介绍了其中有代表性的几个模型；提出复合模型是未来模型的发展方向。为初涉建筑火灾烟气运动数值模拟的研究人员提供了思路。     

一株纤维素分解茵利用枳实废渣产酶条件的研究

以枳实废渣为碳源，对产纤维素酶G2茵进行固体发酵，通过测定FPA、CMC、C1酶活的大小，对其产酶条件进行优化研究。结果表明产酶最适条件为：枳实在发酵前需进行酸处理；氮源为硫酸铵；含水率为70％；初始pH为5～6；发酵周期为6天。在以上最适条件下，G2菌酶活力为FPA：31．8IU／ml，CMC：11．86IU／ml，C1：15．79IU／ml。     

海岸带风暴潮减水的统计分析

在青岛大港观测站连续30年实测资料的基础上,按照年、季、月等时段分别抽样,对风暴潮减水进行了长期统计分析.考虑到海岸地区风暴潮减水的诱因不同,在一维复合极值分布的基础上,提出了"组合分布法".新方法探讨了假设所有数据源于同一分布而产生的重现值估计误差.与年极值法和阈值法的计算结果进行了比较,说明以往算法得到的重现值偏低,并给出了青岛地区受季节变化影响的风暴减水设计重现值.统计表明,青岛大港春、秋、冬季均有风暴减水发生.由于寒潮大风是其产生的主导因素,以冬季的极值减水序列为样本,所得重现值与考虑季节变化得到的重现值相当.说明在实际工程区域,选取主要天气形势产生的水文要素为样本,替代所有观测数据,使统计计算得以简化的做法是可行的.     

芳香型偶氮污染物紫外光谱量子力学指认及不同共轭态偶氮键电子激发研究

偶氮化合物是重要的工业化学品,也是常见的环境污染物,其紫外激发特征及"分子结构-紫外吸收"的构效关系暂未完全明确.本研究借助量子化学计算,通过对波函数与激发态"电子-空穴"的分析,描述偶氮化合物紫外吸收光谱和激发态特征.结果表明:反式偶氮苯实验紫外光谱的第一主要吸收峰应指认为π→π^*跃迁,对应其S₀→S₂激发,电子从最高占据轨道(HOMO)跃迁到最低未占据轨道(LUMO);它的第一激发过程(S₀→S₁)振子强度很小(f=0.031),对光谱贡献可以忽略.反式偶氮苯吸收峰位置与顺式相比普遍红移,表明反式结构中偶氮键通过"桥接效应"形成全局共轭,降低了激发能,对偶氮化合物的紫外吸收产生显著影响;在水溶液中,钠离子对偶氮键的电荷分布存在显著扰动,因此,孤立阴离子模型计算得到的甲基橙光谱与实验存在较大误差."推拉"电子官能团促使甲基橙分子高度极化,与钠离子和水分子作用较强,正确处理偶氮键附近的阳离子扰动是建立预测模型的关键.通过量子化学计算指认偶氮污染物紫外可见吸收光谱能为污染修复、环境工程技术开发、光学材料合成提供理论依据,具有重要意义.     

应用因子分析法研究赤潮特征有机物

根据赤潮发生时海水中有机物含量的变化，应用因子分析法研究了与赤潮关系密切的特征有机物。这些有机物包括角鲨烯(SQU)、邻苯二甲酸二异丁酯(DIBP)、邻苯二甲酸二正丁酯(DNBP)、雪松醇(CED)、2，6-二特丁基对甲苯酚(BHT)、3-特丁基羟基苯甲醚(：BHA)、2，6-二特丁基对苯醌(PBQ)等。通过测定海水中特征有机物含量的变化，为赤潮机理的研究。赤潮的监测、预报、防治提供依据。