Levels of PCDD/Fs and trace elements in superficial soils of Pavia Province (Italy)

Trace elements and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soils from rural and light-industrialized sites (n=168) of Province of Pavia (Northern Italy). Most of the trace element values fit in typical ranges of concentrations in soils and are similar to the ones reported for rural sites in Italy or sites with no direct anthropogenic impact. Total concentrations of 2,3,7,8 chlorine substituted PCDD/Fs in superficial soils ranged between 24.4 and 1287 pg g(-1) dw (0.5-28.9 pg WHO(98)-TEQ g(-1) dw). The North Eastern part of the Province presented significantly higher levels (p<0.001) than the rest of the Province for As, Cd, Hg, Pb, Zn and PCDD/Fs. While the existence of a defined heavy metal polluting source for this specific site has been suggested, in the case of PCDD/Fs, profiles were not linked to any specific emission source fingerprint. In the whole extension of Pavia Province, OCDD/F dominated the 2,3,7,8 chlorine substituted congener soil pattern, followed by the 1,2,3,4,6,7,8 hepta-CDD/F congener. Principal Component Analysis (PCA) showed that this profile could not be associated to any described PCDD/F emission source fingerprint and was relatively similar to the baseline deposition of sites with no direct impact of PCDD/F emission sources independently of land use.     

气相色谱法观测本底大气中的甲烷和二氧化碳

根据世界气象组织全球大气监测（ＷＭＯ／ＧＡＷ）开展全球温室气体监测的要求，建立了气相色谱（ＧＣ）法甲烷和二氧化碳（ＣＨ４／ＣＯ２）连续观测系统，概述了该系统厍拿大大气环境局（ＡＥＳ）５个月的组装调试，以及在中国大气本底基准台（ＣＧＡＷＢＯ＿一年多时间里的业务运行和标定情况，且装调试和运动标定，与红餐吸收（ＮＤＩＲ）法，气瓶采样－实验室分析（ＦＬＡＳＫ）法数据，以及与上其它台站观测资料的对比结果表明     

Competing feedback in an idealized tide-influenced delta network

Environmental Fluid Mechanics - The morphodynamic evolution of river deltas is intimately tied to flow and sediment partitioning at bifurcations. In this work, the long-term equilibrium...