## 3 Results and Discussion
### Plants Isotopic Values (C-N-S), Comparison Between Regions
#### 3.1.3 \(\delta^{34}\)S of Plants
According to [PERSON] (2021) and references therein [66], the Rhodope Massif mainly consists of metamorphic and igneous rocks, such as graisesses, marbles, chlorite mica and mica schists, amphibolites, migmatites, granites, grandoiorites, rhyolites, andesites, and dacites. Apart from metamorphic rocks (mica schists and amphibolite schists  
and amphibolites), the Serbo-Macedonian Massif comprises massive outcrops of ophiolites and granites, grandoritories and diorites. The Circum-Rhodope Unit includes sandstones, quartzites, and schists, as well as volcano-sedimentary formations, such as limestones, marbles, crystalline limestones, flysch, cherts, schists, phyllites, and gneisses. The Axios/Vardar Belt is mainly observed in the form of ophiolite complexes, while volcanic schists, phyllites, marbles, cherts, sandstones, and limestones can be observed. The Peonia, Paikon, and Almopia Units can be distinguished. The Axios Belt also has clear volcanic activity features. The Pelagonian Unit is composed of gneisses, gneisses-schists, amphibolites, and granite intrusions. Marbles, phyllites, schists, and sandstones as well as limestones and dolomites are also present. Massive ophiolite tectonic rappes can be observed. The Attic-Cycladic Massif consists of marbles, dolomites, and mica and amphibitic schists. The metamorphic evolution of the Attic-Cycladic Massif is mainly characterized by massive granitic intrusions. The Parmassos Unit is characterized by the presence of massive carbonates (limestones and dolomites). These shallow-water carbonate platforms host the three bauxitic stratigraphic horizons, B1, B2, and B3. The Pindos Unit is mainly composed of limestones, dolomites, volcano-sedimentary formations, radiolaries marls, pelites, sandstones, and cherts. The massive ophiolitic sequence in Greece is thrust onto the Pindos unit by obduction. Limestones and dolomites are the main formations in the Gavrovo-Tripolis Unit. An HP metamorphic unit--also known as a \"Phyllite-Quartzite (PQ) nappe\"--is occurring beneath the Gavrovo-Tripolis carbonate series. The Ionian Unit is mainly characterized by the presence of a carbonate stratigraphic sequence (neritic and pelagic limestones, dolomites, slates, and cherts) overlying the evaporites. This unit is thrust onto the Paxos (or Pre-Apulian) Unit, and it is also associated with a metamorphic \"Plattenkalk\" (platy-like limestones) series (also known as \"Mani Unit\" or Talea Ori). The Paxos Unit is a typical shallow-water carbonate autochthonous platform overlying evaporites (e.g., gypsum). It can only be observed in the Paxos, Lefkada, Kefalonia, and Zakythos Islands. Plants from different areas present distinct patterns of nitrogen and sulfur isotope ratios. Plants from the Naousa region and the Kiato's coastal areas differ in their \(\delta^{15}\)N and \(\delta^{34}\)S, indicating an enrichment in them from the Northern regions towards the Southern ones (Figure 6). The \(\delta^{15}\)N and the \(\delta^{34}\)S isotopic data probably suggest that they have been influenced (i) by the climate mainly due to the enrichment of \(\delta^{15}\)N as a result of relatively low rain accumulation [48], (ii) by the marine aerosol in the case of \(\delta^{34}\)S dataset, (iii) by the fertilizers and (iv) by the soil reflecting the \(\delta^{34}\)S dataset (Figure 7). However, taking into account that the plants' sulfur isotopic values across the country are not really complicated and fluctuated, despite its complex geology (Figure 7), it can thus reasonably be assumed that the \"sea-spray effect\", along with rainfall, plays a crucial role in the homogenous range of sulfur isotopic values.