Date of Award

1-1-2012

Document Type

Campus Access Thesis

Department

Marine Science

First Advisor

Claudia Benitez-Nelson

Abstract

Water column samples from the Chukchi Sea were collected during June-July 2010 as part of the NASA ICESCAPE (Impact of Climate Change on the Eco-Systems and Chemistry of the Arctic Pacific Environment1.34) mission to study phosphorus (P) partitioning and distribution. Our results indicate that P concentrations are spatially heterogeneous with profound changes in both concentration and speciation as waters originating in the Pacific Ocean move through the Bering Strait and Chukchi Sea into the Arctic Ocean. Soluble reactive P (SRP) concentrations increase by 0.6 M northwards while dissolved organic P (DOP) concentrations decrease by 0.3 M. However, total P concentrations are similar north (1.34 ├é┬▒ 0.47 M) and south (1.24 ├é┬▒ 0.62 M). P speciation results show that DOP dominates the total (dissolved + particulate) P pool in the south (45 ├é┬▒ 17%) and SRP dominates the total P pool in the north (73 ├é┬▒ 13%). DOP is produced via biological activity, as evidenced at the head of Barrow Canyon and the Southern Chukchi (SC) hot spot, where DOP comprises greater than 60% of the total P pool. Particulate P on the other hand is a mixture of biological particles and terrestrially derived sources, as evidenced by the relationships between chlorophyll a (Chl a) and particulate inorganic P (PIP) (R2= 0.46) and POP (R2= 0.47). High molar ratios of particulate organic carbon (POC) to particulate organic P (POP) (slope = 194.5 ├é┬▒ 7.3; R2= 0.65) and POC to particulate organic nitrogen (PON) (slope = 17.0 ├é┬▒ 0.89; R2= 0.51) indicate the preferential remineralization of P relative to carbon and nitrogen. Since primary productivity in the Chukchi Sea is nitrogen limited, large amounts of SRP and DOP accumulate in the water column due to biological activity and preferential remineralization of POP. The Chukchi outflow waters therefore supply a source of the high dissolved P concentrations to the upper halocline waters observed in the Beaufort Sea and the Canada Basin where this reservoir of P is used to fuel additional production.

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