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Heavy metal pollution is becoming a serious issue in developing countries such as China, and the public is increasingly aware of its adverse health impacts in recent years. We assessed the potential health risks in a lead-zinc mining area and attempted to identify the key exposure pathways. We evaluated the spatial distributions of personal exposure using indigenous exposure factors and field monitoring results of water, soil, food, and indoor and outdoor air samples. The risks posed by 10 metals and the contribution of inhalation, ingestion and dermal contact pathways to these risks were estimated. Human hair samples were also analyzed to indicate the exposure level in the human body. Our results show that heavy metal pollution may pose high potential health risks to local residents, especially in the village closest to the mine (V1), mainly due to Pb, Cd and Hg. Correspondingly, the residents in V1 had higher Pb (8.14 mg/kg) levels in hair than those in the other two villages. Most of the estimated risks came from soil, the intake of self-produced vegetables and indoor air inhalation. This study highlights the importance of site-specific multipathway health risk assessments in studying heavy-metal exposures in China.

The third-order optical nonlinearity and response time of Au nanobipyramids have been investigated by using optical Kerr effect technique. Large third-order nonlinear optical susceptibility ( χ(3)) and ultrafast optical response time have been obtained at the longitudinal surface plasmon resonance (LSPR) wavelength. As the excitation laser wavelength varies from non-resonance wavelength of 780 nm to the LSPR wavelength of 825 nm, χ(3) increases from 7.4 x 10-14 to 3.9 x 10-13 esu, the fast component of the response time decreases from 141 ± 23 to 83 ± 8 fs and the ratio of the fast component remains around 48%, while the slow response time decreases from 3200 ± 200 to 2310 ± 158 fs. The large enhancement of χ(3) is due to the large local field enhancement caused by the surface plasmon resonance, and the shortening of the response times are induced by the increased probability of the electron-electron and electron-phonon scatterings in the nanosystem. This significant ultrafast optical property in Au nanobipyramids has great application in future ultrafast information processors. [ABSTRACT FROM AUTHOR]