Different fates of four poorly soluble trace elements in the Pacific Ocean

After having demonstrated that aluminum (Al), lead (Pb), manganese (Mn) and cobalt (Co) are uniquely related to ocean circulation in the North Pacific (Zheng et al., 2019), Zheng and co-authors (2022, see reference below) present the full-depth distributions of these elements in the western South Pacific, which include meridional sections along 170°W (GEOTRACES section GP19). In this study, they performed a detailed description of the physical speciation of these tracers: dissolved (d) and total dissolvable (td) concentrations were measured allowing them to calculate labile particulate (lp). This allowed them to establish the first order processes that drive the biogeochemistry of Al, Mn, Co, and Pb in the Pacific Ocean. Among others:

  • Dissolved Al, dMn, dCo, and dPb are distributed differently in the Pacific Ocean due to different major sources and different biogeochemical cycling. They suspect that a tight connection between the weathering on land and the distribution of dAl in the Pacific Ocean. In contrast, strong sources of dMn, dCo, and dPb occur in the North Pacific. The major source of dMn and dCo is continental shelf sediments, and the major source of dPb is anthropogenic aerosols.
  • Mn/PO4 and dCo/PO4 ratios in the surface mixed layer indicate that dCo is deficient for phytoplankton in a large area of the Pacific, although dMn is deficient only around the equator and to the south of the STF. Dissolved Pb is highly concentrated in the North Pacific, indicating that anthropogenic pollution still dominates the oceanic distribution of dPb in this area.
Figure: Full-depth sectional distributions of dAl, lpAl, dMn, dCo, and dPb along GP19 (170 W) in the South Pacific and GPc06 (160 W) in the North Pacific. Warm colours indicate higher concentrations. The data for the North Pacific were acquired from (Zheng et al., 2019). The white line contour shows potential density anomaly (sq). The black dots show data points. EAC: East Australian Current; EUC: Equatorial Under Current; NEC: North Equatorial Current; LCDW: Lower Circumpolar Deep Water; AAIW: Antarctic Intermediate Water; EqPIW: Equatorial Pacific Intermediate Water; NPIW: North Pacific Intermediate Water; STMW: Subtropical Mode Water; CMW: Central Mode Water.


Zheng, L., Minami, T., Takano, S., & Sohrin, Y. (2022). Distributions of aluminum, manganese, cobalt, and lead in the western South Pacific: Interplay between the South and North Pacific. Geochimica et Cosmochimica Acta338, 105–120. doi:10.1016/j.gca.2022.10.022

Zheng, L., Minami, T., Konagaya, W., Chan, C.-Y., Tsujisaka, M., Takano, S., Norisuye, K., & Sohrin, Y. (2019). Distinct basin-scale-distributions of aluminum, manganese, cobalt, and lead in the North Pacific Ocean. Geochimica et Cosmochimica Acta254, 102–121. doi:10.1016/j.gca.2019.03.038

Latest highlights

Overlooked riverine contributions of dissolved neodymium and hafnium to the Amazon estuary and oceans

Xu and colleagues investigated the isotopic composition of dissolved neodymium and hafnium along the entire salinity gradient of the Amazon estuary.

Pulling back the veil on reversible scavenging of lead

This work further contains the role that reversible scavenging may play in the cycling of lead in the ocean, an ever-evolving global experiment where lead contamination can be tracked in real-time.

Extremely high radioactive levels in the manganese nodules

Volz and co-authors demonstrate that radioisotopes in the manganese nodules mostly exceed exempt activity levels…

The North Pacific Ocean, a key actor for the zinc oceanic cycle

Sieber and his colleagues lift the veil on some of the mechanisms that control the behavior of zinc in the Pacific Ocean, and more globally.