Early diagenesis and benthic fluxes in Manfredonia Gulf (Southern Adriatic sea)
Spagnoli F; G. Bartholini; M. Marini; P. Giordano; D. McCorkle; F. Fiesoletti; A. Specchiulli;
The Gulf of Manfredonia is situated in the western part of
Southern Adriatic Sea. This shallow gulf is considered a
complex area, presently not well studied (as opposed to the
Northern Adriatic Sea), where anthropogenic pressure plays
an important role for pollution phenomena and alteration of
the marine ecosystem.
The aim of this study was to investigate early diagenesis
processes that produce benthic fluxes affecting the chemistry
of water column. Two oceanographic cruises were carried out
in late summer 2002 and in late winter 2003 to evaluate the
seasonal variations of early diagenetic processes. Sediment
cores were collected in two sites (inside and in the offshore
boundary of the gulf) in which high sedimentation processes
occur. Parameters on the solid fraction and pore waters
profiles of TCO2, NH3, NO3, PO4
3-, SO4
2-, alkalinity, Fe, Mn,
Ca and Mg were determined in each site. Benthic fluxes were
measured using two benthic chambers in each site.
The 234Th profiles show a more intense bioturbation in the
firsts centimetre of sediment in the inner station and the
sedimentation rate, calculated by 210Pbex and 137Cs profiles,
ranging from 0.40 gcm-2 y-1 in the inner shelf to
0.49 gcm-2 y-1 in the outer gulf. In winter, pore water profiles
suggest oxic and anoxic degradation of reactive organic matter
less intense and occurring in a thinner layer close to the
sediment-water interface in both site Reactive organic matter
degradation products also show an intense irrigation in the
firsts centimetres of sediments in both stations. During the
summer, the pore water profiles reflect remineralization
processes limited to a very thin layer close to the sediment
water interface in both stations but higher in the shallowest
site. Measured benthic fluxes will be compared with the fluxes
obtained by pore water modelization to investigate sedimentwater
interface processes.
2004 - Abstract in rivista
Geochimica et cosmochimica acta 68 (2004): 348–348. doi:10.1016/j.gca.2004.05.008
Keywords: early diagenesis, Adriatic Sea