(~LR (1987) 34 ( 11 ) C. Chemical Oceanography 949

sediment-water interface represented 37% of the annual oxygen uptake rate. Comparison with pre- vious studies shows that rapid sediment accumu- lation and the lack of bioturbation control an unusually high degree of sulfide retention. Curric- ulum in Mar. Sci., Univ. of North Carolina, Chapel Hill, NC 27514, USA.

87:6237 Chanton, J.P., C.S. Martens and M.B. Goldhaber,

1987. Biogeochemical cycling in an organic-rich coastal marine basin. 8. A sulfur isotopic budget balanced by differential diffusion across the sediment-water interface. Geochim. cosmochim. Acta, 51(5): 1201-1208.

The sulfur isotopic composition of the sulfur fluxes occurring in the anoxic marine sediments of Cape Lookout Bight, N.C., U.S.A., was determined, and the result of isotopic mass balance was obtained via the differential diffusion model. Seasonal pore water sulfate 834S measurements yielded a calculated sulfate input of 0.6 ppt. An isotope mass balance equation based upon the fluxes at the sediment- water interface successfully predicted the isotopic composition of the buried sulfur flux within 0.5, thus confirming that isotopes diffuse in response to their individual concentration gradients. Curriculum in Mar. Sci., Univ. of North Carolina, Chapel Hill, NC 27514, USA.

87:6238 Crill, P.M. and C.S. Martens, 1987. Bingeochemical

cycling in an organic-rich coastal marine basin. 6. Temporal and spatial variations in sulfate reduction rates. Geochim. cosmochim. Acta, 51(5):1175-1186.

Rates of sulfate reduction were measured over a 3 year period in the anoxic nearshore sediments of Cape Lookout Bight, North Carolina, using both a tube incubation method and a 3~S-sulfate direct injection technique. The methods yielded similar depth-integrated rates over the upper 30 cm ranging from less than 10 mol SO:4.m-2.y ~ in winter to greater than 50 tool SO=4.m-~.y i in summer. There were also seasonal changes in the Arrhenius acti- vation energies for the sulfate reduction rates indicating that the assumption that Ea is constant with temperature is not always valid. A subsurface rate maximum was observed to develop during the summer months which accounted for 28 percent of the annual depth-integrated sulfate reduction rate. Mail Stop 483, NASA Langley Res. Center, Hamp- ton, VA 23665, USA.

87:6239 del Olvido Chereguini, Maria, 1986. [A study of the

nitrogen cycle in Santanfler Bay, Spain.] Boln Inst. esp. Oceanogr., 3(3):23-40. (In Spanish, English abstract.) Inst. Espanol de Oceanogr., Centro Costero de Santander, Apartado 240, 38080 Santander, Spain.

87:6240 Heggie, David, Gary Klinkhammer and Douglas

Cullen, 1987. Manganese and copper fluxes from continental margin sediments. Geochim. cos- mochim. A cta, 51 (5): 1059-1070.

Total dissolvable Cu and Mn have been measured in seawaters collected from the continental shelf of the eastern Bering Sea. Copper concentration of ( 3 nmole kg ~ were measured over the shelf break but concentrations increased to ~ 4 nmole kg L inshore of a hydrographic front over the 100 m isobath. Manganese concentrations also were low over the shelf break, ( 1 0 nmole kg t, and increased sys- tematically to concentrations ~10 nmole kg ' in- shore of the hydrographic front. Depth distributions of Mn at all continental shelf stations showed gradients into the sediments, with concentrations typically ~20 nmole kg -~ in a bottom layer extend- ing about 30 m off the bottom. Benthic Cu and Mn fluxes are indicated by cross-shelf pore water profiles that show interfacial concentrations more than an order of magnitude greater than in bottom water. These data and the results of a model of metal transport across the shelf suggest that Cu and Mn fluxes estimated at 2 and 18 nmole cm-2y ', respec- tively, from continental shelf sediments may be one 'source' of these metals to the deep sea. Bur. of Mineral Resour., Div. of Mar. Geosci. and Petro- leum Geol., P.O. Box 378, Canberra 2601 ACT, Australia.

87:6241 Klump, J.V. and C.S. Martens, 1987. Bingeochemical

cycling in an organic-rich coastal marine basin. 5. Sedimentary nitrogen and phosphorus budgets based upon kinetic models, mass balances, and the stoichiometry of nutrient regeneration. Geochim. cosmochim. Acta, 51(5): 1161-1173.

Sedimentary nitrogen and phosphorus budgets are estimated for Cape Lookout Bight, North Carolina using 3 related approaches: (l) a kinetic model of solid phase diagenesis; (2) direct measurements of nutrient burial and regeneration; and (3) nutrient recycling rates estimated from annual rates of sulfate reduction and the SO4:NH4 and SO4:PO 4 stoichi- ometry of nutrient regeneration. The mass balances derived agree reasonably well and indicate that approximately 30% of the total nitrogen and 15% of