Distribution of size-fractionated particulate trace metals collected by bottles and in-situ pumps in the Gulf of Maine–Scotian Shelf and Labrador Sea

Abstract

The distribution of size-fractionated particulate trace metals (Al, Fe, Mn, Pb, Cu, V, and Co) was investigated in the Gulf of Maine–Scotian Shelf and Labrador Sea by collection of particulate matter using water bottles (Go-flo) and large volume in-situ pumps (Challenger Oceanic Systems and Services). Trace metal procedural filter blanks for Poretics membrane filters (0.4- and 10 μm pore size) and Nitex screens (53 μm mesh size) were sufficiently low that metal concentrations could be measured reliably. These results validate the use of Challenger Oceanics Systems and Services in-situ pumps for collection of particulate trace metals (Al, Fe, Mn, Pb, Cu, V, and Co) in shelf, slope, and open ocean Atlantic waters. In the Gulf of Maine–Scotian Shelf and Labrador Sea, trace metal concentrations per volume filtered generally decrease with increasing particle size for all metals. In the upper 250 m of slope waters of the Gulf of Maine–Scotian Shelf and in the Labrador Sea, trace metal concentrations in all particle sizes are lower than in shelf waters. Higher particulate metal concentrations in shelf waters are consistent with an increase in the supply of these trace metals with proximity to continental sources. In addition, an increase in particulate trace metal concentrations in shelf waters with depth is attributed to an input from resuspended sediment.