ultrasonication tor 1 hour. The filter is then removed and the solution analyzed 
by fiameless atomic absorption. 
The yields, as determined by addition for Ni and Cu and tracer experiments 
for Cd, are 0.76±.06%, 0.75±.10, 0.70±.08 for Ni, Cu and Cd, respectively. The 
piecision is about ± 10 % at concentrations well above the detection limits of 
0.1 ppb for Cd and 1.0 ppb for Cu and Ni. 
Equipment and reagents are all carefully cleaned prior to Ni, Cu and Cd 
analysis. Polypropylene vials are soaked in 6 M HC1 for 18 hours, rinsed with 
deionized water, and ultrasonicated twice for three hours each time in 6 M HC1. 
They are rinsed at least three times and dried. CoCl 2 6H 0 0 is purified^using 
Dowex-l-X 8 anion exchange resin. It is put on in 9M HC1 and eluted in 4M 
HC1. The APDC solution is purified by filtration through a 0.4 jum micron 
Nuclepore filter followed by five extractions with 20 ml MIBK (methyl 
isobutyl ketone). Filters are acid washed, as all glassware used in the filtration 
is continuously soaked in acid. Blanks are below the detection limits. 
Typical summer pore water profiles are shown in Figures 2-1 and 2-2 for a 
long core and four short cores from the Jamestown North study site in 
Narragansett Bay (located about 0.5 km north of Jamestown Island in 5-10 m 
of water). These profiles are discussed in detail by McCaffrey et al ( 8 ). 
Concentrations of all constituents are far higher in the top centimeter than in 
bottom water (TC0 2 increases from 2.0 to 2.8 mM, NH 3 from ~5 to 100 juM, 
PO 4 ~ from 1-25 juM, etc.). From 1-20 cm the profiles are flat (TCCh, NH 3 , 
HqSiOq) or show decreasing concentrations with depth (PO 4 = , Mn ++ ). The 
lack of a systematic increase is ascribed to transport of metabolites out of the 
sediments by the pumping activity of organisms, rather than by ionic or 
molecular diffusion. The sharp concentration decreases observed for Mn ++ and 
PO 4 = are ascribed to inorganic reaction in the sediment column. Below 
approximately 25 cm, SO 4 = concentrations decrease and concentrations of 
other metabolites increase. Organisms are assumed to be absent, or at least 
ineffective water transporters, below this depth. Metabolite concentrations 
change sympathetically approximately as predicted by organic matter 
decomposition: TC0 2 increases twice as fast as SO 4 — decreases NH 3 increases 
about 1/7 as rapidly as TCO?, and PO 4 = increases about 1/150 as rapidly as 
tco 2 . 
An important point about the flat portion of the profiles is that the TC0 0 
value is considerably higher than can be accounted for by 0 -> reduction, and 
implies anoxic diagenesis. The bottom water TCO-> and 0 o concentrations are 
2.0 and 0.15 mM, respectively. When all 0 2 is consumed, the TC0 0 
concentration will rise to 2.15 mM. NO 3 reduction could conceivably increase 
the value to 2.2 mM. SO 4 - reduction must be postulated as the agent causing 
the further increase to 2.8 mM. 
11 
