B. Cermelj et al., Anoxic mineralization of biogenic debris in near-shore marine sediments (Gulf of Trieste, northern Adriatic), SCI TOTAL E, 266(1-3), 2001, pp. 143-152
Anoxic degradation of sedimentary biogenic debris using closed incubation e
xperiments was studied at two sampling stations in the Gulf of Trieste(nort
hern Adriatic). Production rates of dissolved inorganic carbon (DIC), NH4+,
PO43- and dissolved Si (dSi), and reduction of SO42- were measured and ano
xic mineralization rates were modeled using a first order G-model and multi
-G approach. The depth profiles of these rates revealed an exponential decr
ease indicating that the largest fraction mineralisation of biogenic debris
and SO42- reduction occurs in the surficial sediment layer and on the sedi
ment surface. Comparing the depth-integrated anoxic mineralization rates at
both stations with benthic fluxes of DIC, NH4+, PO43- and dSi measured at
the in situ temperature in the dark, it appears that the DIC and PO43- flux
es are higher because the mineralization mostly occurs at the sediment-wate
r interface, and that besides SO42- reduction, other electron accepters are
involved in the organic matter decomposition pathway in these surficial se
diments. The NH4+ production was higher than the benthic fluxes because of
NH4+ oxidation. The production of dSi was in good agreement with benthic fl
uxes implying that temperature is the main factor of dSi production and ben
thic fluxes in these sediments. (C) 2001 Elsevier Science B.V. All rights r
eserved.