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.

Reversible scavenging, the oceanographic process by which dissolved metals exchange onto and off sinking particles and are thereby transported to deeper depths, has been well established for the metal thorium for decades. Reversible scavenging both deepens the elemental distribution of adsorptive elements and shortens their oceanic residence times in the ocean compared to nonadsorptive metals, and scavenging ultimately removes elements from the ocean via sedimentation. Thus, it is important to understand which metals undergo reversible scavenging and under what conditions. Recently, reversible scavenging has been invoked in global biogeochemical models of a range of metals including lead, iron, copper, and zinc to fit modeled data to observations of oceanic dissolved metal distributions. Nonetheless, the effects of reversible scavenging remain difficult to visualize in ocean sections of dissolved metals and to distinguish from other processes such as biological regeneration. Here, we show that particle-rich “veils” descending from high-productivity zones in the equatorial and North Pacific provide idealized illustrations of reversible scavenging of dissolved lead (Pb). A meridional section of dissolved Pb isotope ratios across the central Pacific shows that where particle concentrations are sufficiently high, such as within particle veils, vertical transport of anthropogenic surface–dissolved Pb isotope ratios toward the deep ocean is manifested as columnar isotope anomalies. Modeling of this effect shows that reversible scavenging within particle-rich waters allows anthropogenic Pb isotope ratios from the surface to penetrate ancient deep waters on timescales sufficiently rapid to overcome horizontal mixing of deep water Pb isotope ratios along abyssal isopycnals.

To better understand the geochemical cycle of dissolved manganese (Mn) in the East China Sea (ECS), the distribution of dissolved Mn across the ECS was investigated during three field studies in 2011 (May, August, and November). The concentration of dissolved Mn decreased across the ECS with distance from the coast. Mn‐rich ECS shelf waters could export to the Kuroshio Waters, and had the potential to influence the northwest Pacific Ocean as well as the Japan Sea. The Kuroshio Waters were devoid of dissolved Mn, so its incursion could be tracked as it entered the ECS continental shelf region (approximately 50 m isobath). Seasonal variations of dissolved Mn in the ECS were significant, with the highest concentrations occurring in summer. Dissolved Mn in the Changjiang Estuary was nonconservative, and significant quantities were removed by net sorption onto suspended particulate matter. A model describing the sorption processes was applied to data for the Changjiang Estuary. Regeneration of dissolved Mn took place in near‐bottom waters of the suboxic zone in August 2011, following extensive consumption of oxygen. The benthic flux of dissolved Mn was estimated based on Mn concentrations in the overlying waters and the near‐bottom waters. A preliminary box model was established to develop a dissolved Mn budget for the ECS. Based on the dissolved Mn content in the ECS and the total input flux, a residence time of 76–350 days for dissolved Mn in the ECS was inferred.