Naslov
Utjecaj dugoročnih promjena oceanografskih svojstava na koncentraciju hranjivih soli u sjevernom Jadranu
(Long-term changes of oceanographic conditions and their impact to the nutrients in the northern Adriatic Sea)

Autori
Ivančić, Ingrid

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Prirodoslovno-matematički fakultet

Mjesto
Zagreb

Datum
17.11

Godina
1995

Stranica
138

Mentor
Degobbis, Danilo

Ključne riječi
hranjive soli ; dugoročne promjene ; Sjeverni Jadran
(nutrients ; long-term changes ; Northern Adriatic)

Sažetak
This work is based on 22 years data series collected at five stations of the delta Po river-Rovinj profile, in the period 1970-1992. A total of about 5000 data related to oceanographic properties, nutrient and oxygen concentrations were analyzed. In addition, 27000 Po river discharge data were also used. The annual models for the oceanographic parameters, nutrient and oxygen concentrations were described in association with the annual model of the Po river inflow. On the basis of these models five characteristic oceanographic seasons, in which predominate specific physical and biological processes, were identified. The long-term changes of oceanographic properties and their influence on the nutrient and oxygen concentrations were analyzed seasonally. The results suggest that the long-term changes until the mid-1980, s were strongly influenced by the freshet of the Po river. Since the mid-1980, s meteorological conditions increased water column stability, especially during the summer, compared to periods with similar freshwater input. In addition, spreading of freshwater and its longer residence in the northern Adriatic were favored. In these conditions the nutrient concentrations were higher than expected from the freshwater load, allowing an increased biological activity. As a consequence, summer and fall bottom oxygen concentrations were even lower than in periods with marked Po river influence. Since the 1980, s significant changes in processes controlling the nutrient concentrations occurred. In this period a decrease of the surface SiO4concentrations during May and June were found, probably as a consequence of the increased diatoms contribution to the phytoplankton community. In addition, since the mid-1980, s a decrease of phosphorus concentration with respect to nitrogen occurred, probably due to changes of their concentrations in the Po river water. Changes in phosphorus and nitrogen appear not affecting the ratio of organic matter production, but probably changed the composition of the produced organic matter.

Izvorni jezik
Hrvatski

Znanstvena područja
Biologija

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