Trace metal distributions and fluxes in the Taiwan Strait

Abstract

The Taiwan Strait plays an important role as a corridor for the transport of water and chemicals between the South China Sea and the East China Sea, two of the largest marginal seas in the world, while receiving terrestrial material from land masses on both sides. In this study, we report on trace metal results in multiple cross-Strait transects during surveys of trace metal distributions and fluxes that reached from the northern South China Sea to the southern East China Sea. Plumes of elevated trace metal concentrations off the mainland China coast and off the northwest coast of Taiwan were documented to reach into the Taiwan Strait. Combining trace metal data with current velocity, obtained from HYbrid Coordinate Ocean Model (HYCOM), trace metal fluxes through multiple cross-sections in the Taiwan Strait were calculated. Seasonal variability in terrestrial source strength and current patterns in the Taiwan Strait dictated trace metal fluxes in different parts of the Strait. The northward fluxes were smaller during northeastern monsoon in the fall/winter because of the greater southward Chinese Coastal Current, which carried terrestrial trace metal sources in its water into the Taiwan Strait. Some trace metals had strong linear relationships with salinity within plume extensions, within a few tens of kilometers off a major river mouth. Results show that varying monsoon-induced water transports led to distinctively different trace metal distributions and fluxes at different times and through different transects across the Taiwan Strait.