## 3 Results and Discussion
### Isotopic Results  
The isotopic composition of \({}^{13}\)C in terrestrial plants ranges as a function of the photosynthetic pathway. There are two main groups of photosynthesis: C3 (Calvin cycle) and C4 (Hatch-Slack cycle) [25], depending on the different enzyme involved in the carboxylation process, atmospheric CO\({}_{2}\) first being incorporated into one three-carbon or four-carbon compound. Most of the plants on Earth follow a C3 cycle (fruits, vegetables, the majority of cereals), having \(\xi^{13}\)C values between \(-30\) and \(-23\%\)[26]. C4 plants (maize, sugarcane, millet, sorghum) present a higher isotopic signature of \({}^{13}\)C, ranging from \(-14\) to \(-12\%\). The isotopic fingerprint of \({}^{13}\)C for the investigated berries was compared with those recorded by other authors for C3 plants [8; 27]. The \(\xi^{13}\)C values of studied samples varied between \(-32\) and \(-23.2\%\), in the range of those reported by [PERSON] et al. (2021) [3] for blueberries and bilberries (from \(-28.6\) to \(-23.9\%\)). Raspberry samples presented the highest \(\xi^{13}\)C values (mean of \(-25.7\%\)), and blackberries had a similar \({}^{13}\)C isotopic signature (mean of \(-26.1\%\)) (Figure 2). Blueberries showed the lowest values (mean of \(-28.2\%\)). The recorded values for blueberry samples are supported by the results of [PERSON] et al. (2018) [8], who obtained lower values (mean of \(-26.2\%\)) for blueberries coming from Eastern Europe (Romania and Poland) versus Italian blueberries (\(\xi^{13}\)C = \(-24.2\%\)). These differences could be explained by plant physiology processes and the agricultural practices used in growing regimes (open field, greenhouse) [28; 29], taking into account that the \({}^{13}\)C isotopic signature of C3 terrestrial plants preserves valuable data related to: (i) internal physiologic characteristics,and (ii) changes in external environment that could influence carbon fixation during the photosynthetic process [30,31]. Plants take up the water from the soil during the growing process and incorporate it into their tissues. Therefore, the \({}^{2}\)H and \({}^{18}\)O isotopic signatures of extracted water from plants (fruits, vegetable, cereals, etc.) will reflect the isotopic fingerprint of water from the soil. This water is practically the ground-water, which is well correlated with meteoric water (precipitation) [32]. The isotope composition of water varies greatly by temperature, latitude, altitude, and precipitation amount [33]. By analyzing the extracted water from berries, data linked to the water source and sample origin could be obtained. In this regard, for all of the investigated berry samples, the \(\delta^{2}\)H values ranged between \(-49.0\) and \(-17.0\%\), and for \(\delta^{18}\)O between \(-4.8\) and \(4.9\%\) (Table 1). The sample with the highest content of hydrogen and oxygen is a cultivated blueberry, from a farm located at 891 m altitude (\(46^{\circ}44^{\prime}42^{\prime\prime}\) N \(23^{\circ}06^{\prime}19^{\prime\prime}\) E, Rasca village, Cluj County). These enriched values could be explained by the progressive process of evapo-transpiration, depending on temperature and humidity: as the blueberry sample is rip, mature, approaching harvest, or in the process of harvest, the lighter isotopes in the berries' water will evaporate more quickly than heavier isotopes [8,34]. The lowest isotopic signatures of \({}^{2}\)H and \({}^{18}\)O were recorded for two raspberry samples coming from conventional production, suggesting a colder region for the water source [35] used to irrigate these cultivars. This explanation is consistent with the mention on the label: the production site of these two samples is a farm located in the mountain area, at a higher altitude, 1400 m a.s.l. (\(46^{\circ}34^{\prime}32^{\prime\prime}\) N \(23^{\circ}28^{\prime}03^{\prime\prime}\) E, Baisoara village, Cluj, Romania).