Variation of sedimentation rate in the semi-enclosed bay determined by 137 Cs distribution in sediment (Ka  stela Bay, Croatia) Ivanka Lovren  ci  c Mikeli  c a, * , Vi  snja Ore  s  canin b , Krunoslav  Skaro a Laboratory for Low-Level Radioactivities, RuCer Bo skovi c Institute, Bijeni cka cesta 54, 10 000 Zagreb, Croatia b Advanced Energy Ltd., V. Prekrata 43, 10 000 Zagreb, Croatia article info Article history: Received 31 October 2015 Received in revised form 23 March 2016 Accepted 30 March 2016 Available online xxx Keywords: Adriatic sea Industrialization Ka stela bay Sedimentation rate Urbanization 137 Cs distribution abstract Purpose of this research was to study the rate at which the semi-enclosed bay such as the Ka stela Bay reacts to the coastal processes of industrialization and urbanization, the extent of the influence of human activities on the bay, and the sediment distribution affected by anthropogenic influence. Temporal and spatial sedimentation rate variations were observed between three studied periods: 1954e2005, 1963 e2005/2006, and 1986e2005/2006. Sedimentation rates were in the following ranges: 0.29e0.49 cm/yr for the 1954e2005 period, 0.58e0.95 cm/yr for the 1963e2005/2006 period, and 0.50e1.32 cm/yr for the 1986e2005/2006 period. The average total sedimentation rates for three periods were 0.41 cm/yr, 0.81 cm/yr, and 0.61 cm/yr, respectively. Sedimentation rate for the individual 1963e1986 period marked with two 137 Cs marker peaks was in the 0.65e1.30 cm/yr range, while the mean value was 1.06 cm/yr. Long-term sedimentation rate increase in the whole Ka stela Bay was observed and clearly connected to the industrialization and urbanization processes in the coastal area. These processes reflect very quickly, in terms of years, in the sedimentation rates. Intensive anthropogenic activities in the coastal area are reflected in the whole bay depending on the amount of the discharged sediment material, topography of the sea bottom, and water currents. Some localized areas of sediment accumulation may form. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Coastal areas are particularly important for human activities which makes the marine environment receiving discharges from these areas very sensitive to anthropogenic influence. It has been established that urbanization and industrialization are among the processes with the largest direct influence on the sedimentation rate changes in the coastal areas (Lu and Matsumoto, 2005). 137 Cs is probably the most frequently used anthropogenic radionuclide for monitoring of the environmental processes (Ayçık et al., 2004; Saxena et al., 2002). It is also one of the most frequently applied tracers for determination of recent sedimentation rates in aquatic environments (Ahn et al., 2006; Kumar et al., 2007; Laissaoui et al., 2008; Lu, 2004; San Miguel et al., 2004; Yao et al., 2008). Determination of the sedimentation rates with the 137 Cs method is suitable for sediments of up to 100 years old (Ahn et al., 2006; Mizugaki et al., 2006; Saxena et al., 2002; Schell and Barnes, 1986). 137 Cs distribution in undisturbed sediment depth profiles reflects the global deposition pattern of 137 Cs due to the atmo- spheric fallout. It is, therefore, possible to determine the maximum 137 Cs activities in sediment columns corresponding to the times of maximum 137 Cs input into the environment. This enables its use as a global geochronological marker. Ka stela Bay coastal area is one of the most industrialized, most urbanized and most densely populated areas in Croatia. It com- prises the city of Split, Ka stela, Solin, and Trogir towns, representing the largest urban agglomeration on the east Adriatic coast. Since the 1950s this area was intensively industrialized and urbanized resulting in a sudden and multiple increase of population. The Split urban region had the most dynamic growth in the second half of the 20 th century. Population of the city itself increased 3.5 times in app. 50 years (Kranj cevi c et al., 2014). The past and present in- dustrial activities include chemical factory “Adriavinil”, cement- works, ironwork and galvanization facility, shipyard, all located in the east part of the area. Agricultural activities are more significant in the west part of the area. However, intensive industrialization and urbanization were not followed by the intensive infrastructure development and various contaminants were discharged into the * Corresponding author. E-mail addresses: ivanka.lovrencic@irb.hr (I. Lovren ci c Mikeli c), vorescan@ gmail.com (V. Ore s canin), kruno.skaro@vip.hr (K.  Skaro). Contents lists available at ScienceDirect Journal of Environmental Radioactivity journal homepage: www.elsevier.com/locate/jenvrad http://dx.doi.org/10.1016/j.jenvrad.2016.03.027 0265-931X/© 2016 Elsevier Ltd. All rights reserved. Journal of Environmental Radioactivity xxx (2016) 1e14 Please cite this article in press as: Lovren ci c Mikeli c, I., et al., Variation of sedimentation rate in the semi-enclosed bay determined by 137 Cs distribution in sediment (Ka stela Bay, Croatia), Journal of Environmental Radioactivity (2016), http://dx.doi.org/10.1016/j.jenvrad.2016.03.027