# Three-Year Follow-Up Assessment of Anthropogenic Contamination in the Nichupe Lagoon
## 3 Results and Discussion
The fact that these parameters, both present in anthropogenic wastewater and both useful as human contamination, significantly change shows that the distribution and concentration will result not only from wastewater inputs, but as previously discussed, the hydrological changes could determine the distribution and concentration. The increasing discharge of nutrients could cause eutrophication, so it is necessary to reduce the load of nutrients toward these key ecosystems for the permanence of the coastal landscape and, therefore, of tourist activities. As nutrients are not toxic to aquatic organisms and humans at low concentrations, nutrient criteria are ecological (not toxicological) and cannot be derived by simple dose-response relationships [35], we calculated the water quality TRIX index to identify the trophic state of the NLS. The results of Table 5 and Figure 5 show how there was an increase in the TRIX values in 2019, with a hypertrophic state. In 2020, because of water dilution due to the Cristobal storm, the trophic state improved, becoming mesotrophic. As mentioned by [36], the problems that affect the environmental condition of the NLS stand out: the sanitary drainage pipes and septic tanks at the hotel zone and surrounding urban settlements are in inadequate conditions, causing water leaks due to insufficient infrastructure to treat sewage seeping into aquifers interconnected with the lagoon system, the lack of regulation for tourist activities on the lagoon bank, the lack of monitoring and sanitation programs, and finally, the unawareness of the population about the level of contamination and environmental deterioration. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Year**} & \multicolumn{1}{c}{**Parameter Caffe**} & \multicolumn{1}{c}{**Salinity**} & \multicolumn{1}{c}{**DO**} & \multicolumn{1}{c}{**NO\({}_{3}\)\({}^{-}\)**} & \multicolumn{1}{c}{**NO\({}_{2}\)\({}^{-}\)**} & \multicolumn{1}{c}{**NH\({}_{4}\)\({}^{*}\)**} & \multicolumn{1}{c}{**SRP**} & \multicolumn{1}{c}{**SRSi**} & \multicolumn{1}{c}{**Chl-\(a\)**} & \multicolumn{1}{c}{**TRIX**} \\ \hline \multirow{6}{*}{2018} & \(\chi^{2}\) & 14.5 & 13.5 & 4.43 & 89.5 & 90.7 & 86.3 & 92.5 & 83.5 & 36.62 & 43.49 \\  & df & 2 & 2 & 2 & 2 & 2 & 2 & 2 & 2 & 2 & 2 \\  & \(p<0.05\) & \(<\)0.001 \({}^{*}\) & 0  
The cluster analysis (Figure 6) showed that the areas with the greatest similarity were the ZII and ZIV (>80%), while the least similar areas were the ZI (70%) and ZV (56%). These last two zones have characteristics since the water has a longer residence time due to its geomorphology. In the case of the ZI, it is the most restricted and least connected with the rest of the NLS, while in the ZV, there are freshwater springs that give it other characteristics [17]. Principal component analysis (Figure 7) indicated that the variables that had the greatest positive relationship with caffeine were OD and Chl-_a_. One of the characteristics of wastewater (traced by caffeine) is to contain nutrients that promote algal growth, which seems to be the case in NLS. The primary producer bloom (higher Chl-_a_) will promote the production of oxygen in the area [37; 38; 39; 40]; this could be seen as a positive outcome, nevertheless, it could lead to a eutrophic state or a toxic algal bloom, as has been reported for the area [4; 41]. Also, it is noteworthy that nutrients are not totally related to caffeine; this could be the result that for the area, the source of caffeine is solely groundwater or direct inputs from the surroundings; nutrient marine inputs [42; 43], besides their release from sediments resuspension [44; 45; 46], are also relevant, thus, PCA shows this.