珠江三角洲地区土壤中二噁英污染水平及其分布特征研究

应用高分辨气相色谱/高分辨质谱(HRGC/HRMS)对珠江三角洲地区土壤中二噁英(PCDD/Fs)的浓度及其分布特征进行了研究。结果表明,土壤样品中PCDD/Fs为118~2 304pg/g,平均值为743pg/g;WHO2005-TEQ为1.09~5.56pg/g,平均值为3.25pg/g。珠江三角洲地区土壤中PCDD/Fs浓度较往年相比稍有下降,且大部分地区土壤中PCDD/Fs污染并不严重。土壤中PCDD/Fs同系物分布以OCDD为主要的特征单体,毒性单体贡献最大的是1,2,3,7,8-PeCDD和2,3,4,7,8-PeCDF,平均占总毒性当量的28.9%和16.3%。对珠江三角洲地区土壤中PCDD/Fs的源分析表明,土壤中PCDD/Fs受污染源影响较小,可能主要来自大气沉降。     

Assessment of the temporal and spatial distribution of atmospheric PCNs and their air–soil exchange using passive air samplers in Shanghai,East China

A total of 47 passive air samples and 25 soil samples were collected to study the temporal trend, distribution, and air–soil exchange of polychlorinated naphthalenes (PCNs) in Shanghai, China. Atmospheric PCNs ranged from 3.44 to 44.1 pg/m³ (average of 21.9 pg/m³) in summer and 13.6 to 153 pg/m³ (average of 40.0 pg/m³) in winter. In the soil samples, PCN concentrations were 54.7–1382 pg/g dry weight (average of 319 pg/g). Tri-CNs and tetra-CNs were two dominant homolog groups in air samples, while di-CNs were also found at comparable proportions to tri-CNs and tetra-CNs in soil samples. Most air and soil samples from the industrial and urban areas showed higher PCN concentrations than those from suburban areas. However, some soil samples in urban centers presented higher PCN concentrations than industrial areas. Analysis of PCN sources indicated that both industrial thermal process and historical usage of commercial PCN mixtures contributed to the PCN burden in most areas. The fugacity fraction results indicated a strong tendency of volatilization for lighter PCNs (tri- to hexa-CNs) in both seasons, and air–soil deposition for octa-CNs. Moreover, air–soil exchange fluxes indicate that soil was an important source of atmospheric PCNs in some areas. The results of this study provide information for use in the evaluation of the potential impact and human health risk of PCNs around the study areas.

     

唐山地震高烈度区Vs30经验估计研究∗

以唐山地震高烈度区场地条件为背景,选取并整理其中 701 个实际钻孔的剪切波速测试资料,分别计算国际上较普遍采用的场地分类指标 V_se和 V_s30,初步建立了适用于唐山地区 V_se与 V_s30的对应关系,利用 Boore 提出的速度梯度外推法,回归得到了唐山地区 V_s30的经验模型与拟合参数,并与四个地区(北京、新疆乌鲁木齐、加利福尼亚、 日本 KiK-net)的经验公式进行了对比。结果表明,场地分类指标 V_se和 V_s30之间具有强相关性,不同地区数据回归得到的经验公式能够得到很好的预测结果,也能对场地类别相近地区的剪切波速模型预测提供参考。