The particulate phase is fundamental to the oceanic inventory, transport, and bioavailability of trace metals (TMs), yet their basin-scale dynamics remain poorly understood. Here, we investigated the distributions of particulate TMs (pTMs) along 40°S (GEOTRACES GA10 transect) in the South Atlantic Ocean. Labile and refractory pTM concentrations spanned six orders of magnitude from 10⁻¹ to 10⁶ pmol kg⁻¹. Refractory pTMs were associated with lithogenic particles and labile pTMs were linked to biogenic and authigenic particles. Near the Río de la Plata estuary, labile and refractory pTMs were enhanced by fluvial discharge and sediment resuspension in the coastal region. Benthic inputs in the Argentine Basin (>4000 m) induced strong near-bottom enrichments of pTMs with the labile fraction of the particles contributing 30–75% of total concentration. In addition, the ratios between labile pCo, pNi, pCu, pZn and labile particulate phosphorus increased by 5–100 times from surface to bottom waters, reflecting particle cycling, remineralization with preferential phosphorus release, scavenging, and benthic inputs. At depths, Mn, Pb, and Co showed active dissolved-labile particulate TM exchange and boundary influence, while Ni, Cu, Zn, and Cd were increasingly dominated by the dissolved phase with increasing depth. This demonstrates that separating labile and refractory particulate fractions is critical for resolving ocean TMs cycles. These findings highlight the fundamental role of particle cycling in regulating the transport, transformation, and bioavailability of TMs in the South Atlantic Ocean.

暂无