Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

silicate and orthophosphate were approximately 6, 15 and 1.4
pM respectively on both occasions. Phosphate concentrations
in the upper 50 m decreased to 1 pm in August. A11 nutrient
concentrations were dramatically lower during August in the
upper 5 m. The very low phosphate (0.3 pm) , silicate (6 pm)
and nitrate (1 pm) concentrations observed in this water is
likely a result of ice melt and run-off from the island.
Increased concentrations of suspended particulate organic
carbon in August (Table 4.4) and reduced nutrient
concentrations in the upper well m-ixed layer reflect the net
increase in suspended particulate matter due to primary
production by phytoplankton and ice algae. Within the upper
part of the halocline, a distinct nutrient maximum was
observed on all three sampling trips at a depth of between
100 - 120 m and a salinity of 33.1 ppt. Concentrations of
dissolved silicate, nitrate and orthophosphate reached levels
of 38, 17 and 2.2 pM respectively in June. Maximum phosphate
was lower in August (1.8 pM) and nitrate lower in May (15
pM). This maximum is a distinctive feature of the Central
Arctic Ocean which has been postulated in recent publications
to have its origins within the Arctic Basin rather than with
intruding Bering Sea water. The mechanism suggested is brine
formation and drainage from the large continental shelves
(Jones and Anderson, 1987; Melling and Lewis, 1982; Aagaard
- et &., 1981, 1985). Nutrient depth profiles for all three
trips are shown in Figures 4.3 - 4.5.
4.4.2 Particulate Orsanic Carbon and Nitrsqen
The suspended matter, particulate organic carbon (POC)
and particulate organic nitrogen (PON) concentrations for a%P
three trips are summarized in Table 4.4. Values at all
depths (except 125 m) were generally lower than
concentrations measured by Gordon and Cranford (1985) at a
deep water sampling site (85'~, 2000 m) in the Canada Basin
where concentrations of suspended particles might be