Metallic elements and Pb isotopes in PM2.5 in three Chinese typical megacities: spatial distribution and source apportionment.

Heavy metal pollution in fine particulate matter (PM2.5) is a serious environmental and health concern in China, particularly during winter. Here, we detected 40 elements in 24 h integrated daily PM2.5 samples collected in January 2014 from three typical Chinese metropolises (Beijing, Changchun, and Chengdu) to reflect elemental spatial variations, local sources, and regional transport. The measured elemental concentrations in Changchun were 11.1% and 48.4% higher than those in Beijing and Chengdu, respectively. Thus, PM2.5 from Changchun exhibited high levels and diversity in the elemental profile (characterized by high concentrations of industrial emission elemental markers). The results of elemental ratios and Pb isotopes proved that, except for a coal combustion source, vehicular emissions contributed more to PM2.5 heavy metals in Beijing than in the other two cities; Changchun PM2.5 elements received large contributions from industrial sources, including iron and steel manufacturing, and automobile industry. Moreover, crustal dust from long-range transport of regional air masses from the northwest regions of China played a crucial role in determining elemental levels in Beijing and Changchun, accounting for more than 50% of source intensity. However, a specific dominant source was not determined in Chengdu; the contribution of anthropogenic dust, mainly from construction activities, needs to be paid attention in Chengdu eastern area. This study contributed to enhancing our understanding of elemental spatial distribution characteristics and sources and to setting more judicious standards and strategies for PM2.5 bound heavy metals in China.

[Intrahepatic localization of a pancreatic pseudocyst]. / Localisation intra-hépatique d'un faux kyste du pancréas.

Intrahepatic false cysts of the pancreas are rarely observed, and only 5 cases have been reported in the published literature since 1965. Recent publications concerning false cysts located adjacent to or within abdominal parenchymas are reviewed. The most common sites are renal and splenic. Radiologic images usually simulate an intravisceral tumoral lesion, even when the false cyst is in contact only with the parenchyma, because of inflammatory changes. Diagnosis depends on complete radiographic exploration of the pancreas, including ultrasonography, a CT scan, and coeliomesenteric arteriography if possible, to detect possible signs of pancreatitis. Ultrasound guided cyst puncture is of marked diagnostic and possible therapeutic value.