Short‐term sediment trap fluxes from Chatham Rise, southwest Pacific Ocean

Abstract

Sediment trap, nephelometer, and particulate matter (PM) data were collected in the vicinity of the Subtropical Convergence, north of Chatham Rise (42–43°S), southwest Pacific Ocean, in austral autumn 1992. Free‐floating cylindrical sediment traps were deployed below the euphotic zone at 200‐, 300‐, and 500‐m water depths. Increases in total mass flux and concomitant proportional decreases in other particulate fluxes (total carbon, nitrogen, and phosphorus) with depth reflected the collection of relatively refractory material, enriched in particulate carbon, as evinced by increases in C: N and C: P ratios below 300 m. Nephelometer and PM concentration profiles indicate that resuspension of sea‐floor sediments from the nearby submarine high (Chatham Rise) probably contributed to the observed increase in total mass flux with depth. Published pCO2 estimates, biological productivity data, and moderate particulate fluxes, as indicated by the present study suggest that oceanic water types east of New Zealand may be a biologically mediated regional sink for atmospheric CO2.

Temporal coupling between surface and deep ocean biogeochemical processes in contrasting subtropical and subantarctic water masses, southwest Pacific Ocean

“…From this analysis, it is a possible that particles originating from the coastal waters off the east coast, North Island, and from Chatham Rise may have been collected by the STM trap. Sediment resuspension is recognized as an important process along the flanks and crest of Chatham Rise [ McCave and Carter , 1997; Nodder , 1997] and material may also be advected from coastal waters into the Wairarapa Eddy and transported to the STM site. If we assume that the influence of coastal processes extends to the 1500 m isobath, then 11% of the STM particle source area lies within the coastal zone of eastern North Island for particles sinking at 100 m d −1 .…”

New particle formation in coastal New Zealand with a focus on open-ocean air masses

“…Some of the previous work has shown that both DMS (Harvey et al, 1993) and non-sea-salt sulfate concentrations in fine aerosols (Li et al, 2018) are higher during the summer than during the rest of the year. Another factor making Baring Head special is the closeness of the biologically active Chatham Rise region (Murphy et al, 2001;Nodder, 1997), described in detail by Law et al (2017). One previous study showed that coarse mode aerosols originating from this biologically active area had high alkalinity caused by high calcium concentrations originating from plankton debris (Sievering et al, 2004).…”

New particle formation in coastal New Zealand with a focus on open ocean air masses

“…Some of the previous work has shown both DMS (Harvey et al, 1993) and non-sea-salt sulfate concentrations in fine aerosols (Li et al, 2018) are higher during the summer than during the rest of the year. Another factor making Baring Head special is the closeness of the biologically active Chatham Rise region (Murphy et al, 2001;Nodder, 1997), described in detail by Law et al (2017). One previous study showed that coarse mode aerosols originating from this biologically active area had high alkalinity caused by high calcium concentrations originating from plankton debris (Sievering et al, 2004).…”