Yi-Tang Huang

Effects of acidic processing, transport history, and dust and sea salt loadings on the dissolution of iron from Asian dust

[1] Aerosol particles collected over the East China Sea (ECS) were analyzed for water-soluble Fe (Fe s ), total Fe (Fe T ), and other chemical species. Eight samples were classified as high Asian dust (HAD) on the basis of total Al concentrations >1500 ng/m 3 . Comparisons with low Asian dust (LAD) samples showed that unlike Fe T or most other substances, the percentage of Fe T soluble in deionized water (%Fe s ) was lower in the HAD samples. The %Fe s in the HAD samples varied with transport pattern and air mass history. As the difference in Fe s concentrations between HAD and LAD is relatively small and HAD occurs several days each year, the supply of Fe s through dry deposition to the surface ocean may be less sporadic than previously thought. Soluble Fe correlated with non-sea-salt sulfate, water-soluble organic carbon, and nitrate, possibly because of an anthropogenic, relatively soluble, form of Fe or enhanced dissolution caused by reactions with anthropogenic acids. Sea salt loadings evidently have a negative effect on %Fe s , presumably due to buffering effects of the salts. Dust concentrations and %Fe s followed an inverse power law relationship with a moderate correlation, suggesting that the %Fe s may be increased by acid processing during transport as dust loadings gradually decrease.

Tungsten and other heavy metal contamination in aquatic environments receiving wastewater from semiconductor manufacturing

Through analyses of water and sediments, we investigate tungsten and 14 other heavy metals in a stream receiving treated effluents from a semiconductor manufacturer-clustered science park in Taiwan. Treated effluents account for ∼ 50% of total annual river discharge and <1% of total sediment discharge. Dissolved tungsten concentrations in the effluents abnormally reach 400 μg/L, as compared to the world river average concentration of <0.1 μg/L. Particulate tungsten concentrations are up to 300 μg/g in suspended and deposited sediments, and the corresponding enrichment factors are three orders of magnitude higher than average crust composition. Surprisingly, the estimated amount of tungsten exported to the adjacent ocean is 23.5 t/yr, which can approximate the amount from the Yangtze River should it be unpolluted. This study highlights the urgency of investigating the biological effect of such contamination.

Evaluating real-time air-quality data as earthquake indicator.

A catastrophic earthquake, namely the 921-earthquake, occurred with a magnitude of M(L)=7.3 in Taiwan on September 21, 1999, causing severe disaster. The evaluation of real-time air-quality data, obtained by the Taiwan Environmental Protection Administration (EPA), revealed a staggering increase in ambient SO(2) concentrations by more than one order of magnitude across the island several hours prior to the earthquake, particularly at background stations. The abrupt increase in SO(2) concentrations likely resulted from seismic-triggered degassing instead of air pollution. An additional case of a large earthquake (M(L)=6.8), occurring on March 31, 2002, was examined to confirm our observations of significantly enhanced SO(2) concentrations in ambient air prior to large earthquakes. The coincidence between large earthquakes and increases in trace gases during the pre-quake period (several hours) indicates the potential of employing air-quality monitoring data to forecast catastrophic earthquakes.