偏振激光雷达在沙尘暴观测中的数据解析

阐述了日本国立环境研究所(NIES)研制的双波长偏振激光雷达的工作原理和主要工作参数,探讨了激光雷达方程在沙尘暴监测中的应用条件,并对激光雷达获取的各种信息进行直观图视化处理.分别用光学强度、后向散射强度、退偏振率、消光系数以及双波长信号比等对沙尘天气的污染特征进行了解析,并对垂直方向沙尘浓度的分布进行了计算.研究表明:退偏振率大于10%时,即可判断为沙尘天气;双波长信号比(P(1 064)/P(532))大于0.4,则表示该期间为沙尘天气;利用消光系数表示气溶胶浓度时,NIES激光雷达观测沙尘气溶胶消光系数超过0.3 km-1(ρ(TSP)约为500　μg/m3),且持续时间超过3　h的沙尘天气现象即可判断为一次沙尘事件.根据激光雷达特有物理量对沙尘气溶胶的不同判定标准,对沙尘事件的强度、持续时间、沙尘云厚度以及沙尘天气的污染特征进行了解析和探讨.      

日本关东南部冬季飘尘中有机碳和元素碳污染现状研究

气溶胶中常含有一定的碳化合物,其中最主要的为有机碳(OC)和元素碳(EC),它们主要来源于化石燃料燃烧等人为活动,并强烈地影响着气溶胶的污染性质。日本关东平原南部初冬季节常发生高浓度飘尘污染,在对这种污染现象的研究中分析了OC和EC在飘尘中的含量,结果表明OC和EC是飘尘中重要的组成部分,二者之和可占质量浓度的20%左右,这也从一个侧面揭示了飘尘的污染状况和污染来源。      

Mercury concentration in hair samples from Chinese people in coastal cities

This investigation was made to estimate current normal concentrations of total mercury in the hair of Chinese coastal people. Hair samples were collected from 659 healthy inhabitants in the areas along the coast and the rivers (such as Shanghai, Ningbo, Dalian, Xiamen, and Zhoushan) of China from Feb. 2005 to June 2006. Total mercury concentrations in the samples were analyzed by the cold vapor atomic adsorption spectrometry method (CVAAS). The results showed the geometric mean concentration of total mercur...     

Methylmercury exposure and health effects in humans: a worldwide concern

The paper builds on existing literature, highlighting current understanding and identifying unresolved issues about MeHg exposure, health effects, and risk assessment, and concludes with a consensus statement. Methylmercury is a potent toxin, bioaccumulated and concentrated through the aquatic food chain, placing at risk people, throughout the globe and across the socioeconomic spectrum, who consume predatory fish or for whom fish is a dietary mainstay. Methylmercury developmental neurotoxicity has constituted the basis for risk assessments and public health policies. Despite gaps in our knowledge on new bioindicators of exposure, factors that influence MeHg uptake and toxicity, toxicokinetics, neurologic and cardiovascular effects in adult populations, and the nutritional benefits and risks from the large number of marine and freshwater fish and fish-eating species, the panel concluded that to preserve human health, all efforts need to be made to reduce and eliminate sources of exposure.     

Assessing noxious effects of dietary exposure to methylmercury,PCBs and Se coexisting in environmentally contaminated rice in male mice

Polychlorinated biphenyls and methylmercury are two of the most ubiquitous environmental contaminants in Guizhou province. Rice is eaten with almost every meal and provides more calories than any single food in Guizhou province. The estimated tolerable daily intake of total mercury, MeHg, Se and PCBs from Guizhou contaminated rice by Chinese people showed that MeHg and/or PCBs exceeded the corresponding limits. The aim of this study was to characterize the effects of exposure to environmental contaminated rice on neurobehavioral development and neurobiological disruptions in mice. Animals were treated from postnatal day (PND) 22 to 91. At PND 26–91 days of age, mice were tested for neurobehavioural development and neurochemical level changes. We showed that dietary exposure to environmentally contaminated rice gave rise to different changes in antioxidants. Reduced superoxide dismutase (SOD) activity and excess increased nitric oxide (NO) indicated aggravation of oxidative status after long-term dietary intake of Hg and PCBs. Neurobehavioral derangement in the central nervous system and significant delay in the Morris water maze test response on PND 91 are correlated with the increased of c-fos/c-jun expression levels in the cerebral cortex. These results suggest that MeHg neurotoxicity might be a greater hazard than that associated with PCB, but PCB may augment the neurobehavioral deficits caused by increased levels of mercury exposure. The simultaneous intake of selenium might have a protective effect on Hg accumulation in the body, and vitamin C might protect mice against the toxic effects of PCBs. However, the protective role of Se and vitamin C is very limited for multiple-agent pollution. Immediately early genes in the brain response to contaminated rice might be dependent on interaction among NO, NO synthase (NOS), SOD and reduced glutathione (GSH). We should be alert to mental health problems in human beings when any kind of Hg- and PCB-polluted food is consumed.