External-forcing modulation on temporal variations of hydrothermalism-evidence from sediment cores in a submarine venting field off northeastern Taiwan.

Jia-Jang Hung,Hsiang-Yi Yeh,Shao-Hung Peng,Yuan-Pin Chang,Jiang-Shiou Hwang,Hans-Uwe Dahms

doi:10.1371/journal.pone.0207774

Jia-Jang Hung, Hsiang-Yi Yeh + Show 4 more

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https://doi.org/10.1371/journal.pone.0207774

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Abstract

The temporal variation of sulfur and metals in core sediments off Kueishantao Islet, a hydrothermal vent site at northeastern Taiwan, was explored to elucidate the changes in submarine hydrothermal emanation over a centennial time scale. The discharge of acidic fluids containing abundant sulfides and dissolved metals results in different concentrations of sulfur and metal accumulating in deposited sediments. In addition to particle size and organic carbon affecting metal contents, the content of total sulfur (TS), which is regarded as an indicator of hydrothermalism, correlates positively and strongly with Fe and other metals; however, it correlates negatively with another index of hydrothermalism, the Al/(Al+Fe+Mn) ratio. The TS content in Core Ks2, the core closest to the vents, increased during 1950–1956, 1968–1970, 1982–1987, 1990–1992, and 2004–2005, but decreased during 1967–1968, 1988–1990, and 1994–1995. The chronological changes in the TS concentration of Cores Ks3 and S2 were very similar to those of Core Ks2 within the aforementioned time spans. The numerous large earthquakes (ML > 5) and typhoons that affect northeastern Taiwan appear to influence hydrothermal emanation and determine the temporal variation of sulfur and metals in sediment cores.

Highlights

Submarine hydrothermalism has recently drawn a substantial attention because it occurs generally in the shallow regimes of global ocean and releases enriched dissolved substances to the upper layer of water columns
As the KST Islet locates on the hot spot of seismic activity and typhoon pathway, we propose a hypothesis that the temporal variability of hydrothermal discharge is dependent mainly on the impact of external forcings on the KST venting field
Given the fact that sulfide and metals in sediments are mainly derived from hydrothermal vents, the distribution of temperature, pH, dissolved sulfide and metals in hydrothermal fluids, plumes and Kuroshio seawater was presented in Table 1 for comparison

Summary

Introduction

Submarine hydrothermalism has recently drawn a substantial attention because it occurs generally in the shallow regimes of global ocean and releases enriched dissolved substances to the upper layer of water columns. Those emanated substances may be either beneficial or harmful to the shallow marine ecosystem. Because the shallow hydrothermal ecosystem is generally maintained by organic carbon synthesis and energy flow driven by both photosynthetic and chemosynthetic processes, the biological community composition can be quite different from that found in the deep-sea hydrothermal ecosystem [1, 2]. It is generally consensus that the biological communities are more diverse and unique in shallow than in deep hydrothermal.

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