Transport and Behavior of Trace Metals in the Tsengwen River and Estuary

曾文河川及河口地區微量金屬之輸送及行為研究

洪佳章(Jia-Jang Hung)

《Terrestrial, Atmospheric and Oceanic Sciences》 1卷3期 (1990/09) Pp. 275-295

摘要

Studies on the transport mechanisms and behaviors of six trace metals (Fe, Mn, Cd, Cu, Pb and Zn)in the Tsengwen river and estuary were performed for the high-flow and low-flow seasons. Dissolvedmetals in the Tsengwen river are slightly higher than those in the pristine rivers but much lower than those in the heavily polluted rivers of the world. The riverborne dissolved Fe, Mn, Cu, Pb and Zn exhibited significant removals in the early estuarine transport; for Cd, however, this was likely controlled by the mixing process in the estuary. Particulate and sediment metals, similar to dissolved metals, showed elevated concentrations in the middle river, but there was little difference throughout estuarine locations. The enriched levels of particulate and sediment metals with reference to backgrounds (shale's metals) were found in a sequence of Pb, Cd＞Zn, Cu＞Fe, Mn.
Trace metals were principally transported by suspended particulates, accounting for over 93% of the total gross fluxes. Particulate Fe and Pb are mostly concentrated in the Fe-Mn hydroxides and crystalline fractions. Particulate Mn, Cu, Zn and Cd distribute rather significantly, in addition to Fe-Mn hydroxides and crystalline fractions, in exchangeable and carbonate phases, carbonate and organic phases, carbonate phase, and exchangeable phase, respectively. The particulate speciation shows little difference between river water and estuarine water. The net fluxes of metals out of the estuary are modeled to be approximately 56%,76%,114%,67%,84% and 73% of dissolved influxes as well as 35%,32%,28%,29%,39% and 50%of particulate influxes, respectively for Fe, Mn, Cd, Cu, Pb and Zn. The imbalance of metals between the dissolved and particulate phases is thought to result from metal deposition in the estuary.

並列摘要

Studies on the transport mechanisms and behaviors of six trace metals (Fe, Mn, Cd, Cu, Pb and Zn)in the Tsengwen river and estuary were performed for the high-flow and low-flow seasons. Dissolvedmetals in the Tsengwen river are slightly higher than those in the pristine rivers but much lower than those in the heavily polluted rivers of the world. The riverborne dissolved Fe, Mn, Cu, Pb and Zn exhibited significant removals in the early estuarine transport; for Cd, however, this was likely controlled by the mixing process in the estuary. Particulate and sediment metals, similar to dissolved metals, showed elevated concentrations in the middle river, but there was little difference throughout estuarine locations. The enriched levels of particulate and sediment metals with reference to backgrounds (shale's metals) were found in a sequence of Pb, Cd＞Zn, Cu＞Fe, Mn.
Trace metals were principally transported by suspended particulates, accounting for over 93% of the total gross fluxes. Particulate Fe and Pb are mostly concentrated in the Fe-Mn hydroxides and crystalline fractions. Particulate Mn, Cu, Zn and Cd distribute rather significantly, in addition to Fe-Mn hydroxides and crystalline fractions, in exchangeable and carbonate phases, carbonate and organic phases, carbonate phase, and exchangeable phase, respectively. The particulate speciation shows little difference between river water and estuarine water. The net fluxes of metals out of the estuary are modeled to be approximately 56%,76%,114%,67%,84% and 73% of dissolved influxes as well as 35%,32%,28%,29%,39% and 50%of particulate influxes, respectively for Fe, Mn, Cd, Cu, Pb and Zn. The imbalance of metals between the dissolved and particulate phases is thought to result from metal deposition in the estuary.