## 5 Discussion  
It was found out that the trace element concentrations of beach sediments depend on the coastal processes and nonsignificantly varied among years, except for Cu and Zn in 2014. The Mn and Cr showed a clear distribution pattern along the coast during the years. Figure 8: Principal component analysis after normalized varimax rotation, and factorial scores showed according to geographical location (Curonian Spit and mainland coast) in 2011, 2014, and 2018. Manganese concentration ratio was higher on the mainland coast, and it tended slightly to decrease northwards. The Cr concentration ratio was higher in Curonian Spit and increased at the distal end of it where the unloading of the sediments is active. These tendencies indicate that the alongshore sediment transport play a significant role in the distribution of the elements along the coast. The decrease in grain size in the north direction shows that the accumulation processes are conditioned by alongshore sediment transport directed from south to north (Figure 2). The measured amounts of beach sediment volume agree with these statements. Poorly sorted sediments were found in anthropogenically affected sections of the coast (Buitinge, Sventoji, Palanga, and Klaipeda) and in places where the sand grain size depends on the geological framework (Juodkrante-Pervalka stretch). The higher Mn concentration was determined in the sites with higher heavy mineral content and with a reduced beach sediment volume. Finer light mineral fractions such as quartz, feldspar, and muscovite mica are usually washed away, and the fine but heavier particles related to heavy minerals co-occur with coarser quartz particles [35; 61]. Manganese according to the PCA analysis is associated with the second component group--carbonates (Ca and Mg), and this association remained during the investigation years. The dominance of carbonates can be explained by the deposits of detrital dolomite and biogenic calcite found on the mainland coast [21; 36]. The greatest source of calcite and dolomite was found at Klaipeda and gradually decreased towards the south of Palanga [21]. The area southward from Klaipeda strait is less abundant in calcite [21]. The Mn distribution pattern also showed that its main source is at the moraine cliff area (Saipiai-Olando kepure). Its concentration increased during the years probably due to more active erosion on the mainland coast. Carbonate rocks also tend to form compounds with cations of divalent metals such as Cu, Zn, Mn, Sr, Pb, etc. [54]. The Zn pattern shows that its concentration was also the highest close to the moraine cliff area. In addition, enlarged Zn concentration in 2014 and 2018 relates to higher heavy mineral content. The results indicated that its concentration is also linked to the erosion processes. The PCA analysis revealed that Zn concentration in 2011 is associated with sediments from the Curonian Spit, while in 2018 and 2014, there was no concrete association with any of groups. In 2014, the content of Zn was significantly higher than in other investigated years. This suggests that there might be additional sources besides natural ones. The cliff area (49 th--61 st sites) 30 years ago was an active military zone [75], which also could have affected sediments resulting in higher content of Zn. The trace elements emitted in the past could migrate into deeper layers and in erosive areas could re-enter the environment after storms [76]. The Zn, Mn, and Cu content is higher in the 71 st and 73 rd sites, which overlap with the dumping sites of the sediments dredged from the Klaipeda Strait (Figure 1). The dredged sediments are more enriched with trace elements than beach sediments [53]. Higher than average MS values are associated with an increase in heavy minerals, whose content depends on the geological framework, which could enhance after a storm [26]. On the distal end of Curonian Spit the sediment accumulation prevail due to sediments delivered by the alongshore sediment transport [27; 57].