Dissolved Lead in the East China Sea With Implications for Impacts of Marginal Seas on the Open Ocean Through Cross‐Shelf Exchange

Abstract

The distribution of lead (Pb) in the ocean is influenced by human activities. During a cruise in the East China Sea (ECS) in August 2013, we investigated six representative stations and gave the first systematic description of dissolved lead (DPb) distributions after the phasing out of leaded gasoline in China. The DPb concentration in the ECS ranged from 23.8 to 96.7 pmol/kg, with the highest concentrations observed at the surface of the middle shelf, while the lowest concentrations were determined to be in deep samples collected at the shelf break. Vertical profiles of DPb vary with geographic locations, seawater turbidity, hypoxic conditions, atmospheric deposition, and hydrographic regimes. As one of the most important western boundary currents, Kuroshio receives an additional 10–20 pmol/kg of DPb from the ECS shelf through a cross‐shelf exchange process, and approximately (1.1–1.7) × 109 g/yr of DPb was exported through the shelf break area, which will directly join the North Pacific circulation based on a preliminary box model. In addition, the ECS shelf exported another 1.4 × 109 g/yr of DPb from the Tsushima/Korea Strait, which has the potential to influence the northwestern Pacific Ocean as well as the Sea of Japan/East Sea. A residence time of 2–3 months for DPb in the ECS was inferred.

Haptophyte communities along the Kuroshio current reveal their geographical sources and ecological traits

“…As the Kuroshio flows along the ECS shelf break, water exchange between the ECS shelf and Kuroshio occurs through upwelling and cross‐frontal processes (Jiang et al, 2018; Wang & Oey, 2016). The major source of regional nutrient input is the upwelling of Kuroshio subsurface water, while the nutrient load from ECS shelf water may be relatively small (Lee & Matsuno, 2007; Umezawa et al, 2014).…”

Dissolved Fe in the East China Sea Under the Influences of Land Sources and the Boundary Current With Implications for Global Marginal Seas

“…In the ECS, various water masses can be encountered and have different residence times on the broad shelf, which may generate patchy distributions of dFe and other trace elements through complex mixing processes, interactions with terrestrial influx and boundary circulation off the shelf. This kind of patchy distribution and strong seasonality has been observed for other trace elements, such as Al, Mn, and Pb (Jiang et al, 2018;Ren et al, 2015; Z. W. Wang et al, 2016). Furthermore, dFe scavenged or removed in the upper part of water column in given estuary can be regenerated in the near-bottom waters because of hypoxia and dynamic processes at the sediment-water interface.…”

“…Niskin-X bottles (Teflon inner coated and springs externally arranged) mounted to an "X-Vane" sampling system were used to collect discrete profile samples for trace elements (R. Zhang et al, 2015). We did a comparison between X-Vane, "MITESS" from MIT, and CTD-Rosette for trace element measurements in this study, and the results indicates that samples from X-Vane and MITESS were comparable for Fe, Mn, Al and Pb, but the CTD-Rosette system may generate high and erroneous data (Jiang et al, 2018;R. Zhang et al, 2015).…”

“…This process acts as conveyor to carry dFe from different sources (e.g., marginal seas) down to the HNLC area of North Pacific Ocean. Using dissolved lead as a tracer, such an influence can be tracked further eastward until the area of Kuroshio Extension, where conditions are oligotrophic (Jiang et al., 2018).…”

Monsoon‐Facilitated Off‐Shelf Transport of Dissolved Aluminum Across the East China Sea During Summer

“… Temperature‐salinity plots for study stations in the ECS. The solid gray curves are isopycnals, and have σ θ values denoted (Jiang et al., 2018 and references therein). Total data are shown in (a), and the salinity range between 34 and 35 is enlarged in (b).…”