Determination of particulate organic carbon sources to the surface mixed layer of the Canada Basin, Arctic Ocean

Abstract

Stable isotope ratios of particulate organic carbon (POC), together with other tracers, were ana- generally found in the central basin. Isotopically enriched material was found on the shelves, consistent with higher biological production and strongly correlated with in situ carbon-uptake rates. In contrast, offshore in the central basin, there was no significant relationship between d 13 C-POC distributions and either chlorophyll a or aqueous CO 2 concentrations, suggesting that in situ biological production was not the dominant control. Analysis of freshwater sources suggested that the sea ice melt contribution of POC to surface waters in the central Canada Basin exerted a negligible influence on d 13 C-POC distributions, and instead isotopically depleted POC in the surface waters of the central Canada Basin were sourced externally through advective transport of riverine organic matter. We show that alkalinity and meteoric water content can be used to distinguish POC inputs from North American and Russian rivers and our analysis suggests that Russian river inputs are the predominant source of 13 C-depleted organic matter to the mixed layer of the central Canada Basin.

Interannual Variability in the Absorption and Fluorescence Characteristics of Dissolved Organic Matter in the Canada Basin Polar Mixed Waters

“…The presence of brine waters was congruent with higher salinity (25.61−29.34; Figure ) and ice cover (>95%; Figure ) in July−August 2011. Brown et al () found negative f SIM and high salinity in the northwest mixed layer Canada Basin in July−August 2008, indicating convective mixing due to sea ice formation. The higher sea ice cover in 2011 (Figure ) may have also resulted in a lower exposure of DOM to solar radiation in surface waters and limited photobleaching of humic‐like (C1‐C2 and C4) previously identified as photolabile FDOM components (Dainard et al, ; Logvinova et al, ; Stedmon et al, ; Stedmon & Markager, ).…”

Temporal and spatial variability of particle transport in the deep Arctic Canada Basin

“…[, and references therein]. Results of suspended POC collected in the surface mixed layer of the Canada Basin in 2008 and 2009 [ Brown et al ., ] are also shown.…”

Global variability of chromium isotopes in seawater demonstrated by Pacific, Atlantic, and Arctic Ocean samples

“…2F, 2H) have low salinities resulting from addition of sea-ice meltwater, or Mackenzie River runoff (Brown et al, 2014). These samples do not plot with the conservatively mixing Pacific and Atlantic waters in Figs.…”

“…2F, 2H; Table 2). The δ 53 Cr of these samples (+1.47 to +1.53h) are among the highest in the Arctic data set, and have the lowest [Cr] (64-74 ng/kg), as well as low salinity (25.3-25.7), which reflects a larger proportion of water from the Mackenzie River and sea ice melt (Brown et al, 2014). Also at L1.1 (50 m), a sample from the remnant of the winter mixed layer (Jackson et al, 2012) was analyzed in duplicate (Fig.…”