engleski

Assessing the impacts of nutrient sources to the trophic state of the northern Adriatic

Northern Adriatic is one of the most productive parts of the Mediterranean Sea, due to the nutrient discharges of the contributing rivers, affecting the water quality of the marine ecosystem. Nutrient discharges are result of different pressures in the watershed most importantly agriculture and urbanization. This research aims to increase the understanding of how the pressures impact water quality by setting up a model that combines catchment modelling with machine learning approach for water quality assessment. Nutrient loads from watershed have been calculated using ArcView Generalized Watershed Loading Function model. Further, Multi Target Stepwise Model Tree Induction was used to combine nutrient loads from watershed and selected water quality indicators in northern Adriatic. Dataset used in this research comprise physical, chemical and biological parameters, measured at six stations on the profile from the Po River delta (Italy) to Rovinj on the western Istrian coast (Croatia). Developed model simulates chlorophyll-a, dissolved inorganic nitrogen, total phosphorus and oxygen saturation in northern Adriatic based on calculated pressures in the watershed. To assess the trophic state the trophic index- TRIX was used. The model was used to evaluate different management scenarios, such as: upgrade of existing WWTPs for nutrients removal, demographic trends, and increase of agricultural production as well as nutrients reduction measures from agricultural activities. Results show that northern Adriatic has relatively good quality state regarding the current anthropogenic activities. In many cases upgrade of wastewater treatment plants for nutrients removal is not necessary to preserve high water quality. However, in spite of the present good quality state an increase in nutrient-releasing anthropogenic activities (e.g. 20% from agriculture, or 5% population increase without nutrient removal) would likely degrade the northern Adriatic trophic state by one category.

Nutrient sources ; trophic state ; wastewater treatment ; UWWTD ; northern Adriatic

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