Changes in Trends of the Seawater Column Parameters and Sediment Elements’ Concentrations from 2009 to 2018 in the Marina Located in the Northern Adriatic Sea

Assessment of environmental quality within marinas is essential to validate implemented environmental protection measures and to adopt appropriate action plans. Here we present temporal trends over the period from 2009 to 2018 using seasonal analysis of physico-chemical and microbiological parameters in seawater column and measurements of elements’ concentrations in surface sediments of the Marina Punat, located in the northern Adriatic Sea, in order to evaluate improvements and deteriorations in marine environmental quality. Environmental monitoring in Marina Punat is carried out four times per year (in May, July, August, and October) at four sampling points (three are within the marina and one is an outside control point). The parameters analysed in situ in a bottom and surface seawater layer are conductivity, dissolved oxygen (DO), pH, mineral oil, total coliform bacteria, faecal coliforms, and intestinal enterococci. The concentrations of elements K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, Zr, Sn, Hg, and Pb in surface sediments collected twice per year (in May and August) were analysed in the laboratory by the EDXRF technique. The concentrations of elements in sediments are compared to results from 2005, i.e. prior to full operation of wastewater treatment plants deployed in service areas where boats are repaired and antifouling paints (AFPs) are removed from boats’ hulls. There has been a significant improvement in sediment quality in Marina Punat after deployment of the wastewater treatment plants, especially with respect to Cu concentrations close to service areas. An increase in concentrations of V, Fe, Cu, Zn, As, and Pb in surface sediments within the marina due to passive leaching from AFPs is still present. On the whole data set, there were no trends in pH and DO values, however, strongly correlated seasonal trends were observed. The seasonal increase and decrease of DO and pH values in the seawater column are unlikely to be related to the marina’s activities. A quick overview of the status of the environmental monitoring in the marinas in Montenegro has been given. This study provides support data for further improvement of management practices in marinas, both in Croatia and Montenegro.