## 4 Discussion  
Turbidity is an optical property of water that partially scatters light. Suspended sediments are responsible for most of said scattering. Ergo, the more suspended particles, the higher the water's turbidity. The bands more appropriate for TSM estimation, as discussed in [PERSON] et al. [55], depend on its concentration, and for high TSM concentrations the best results are obtained with longer wavelengths (700 nm and beyond). [PERSON] et al. [56] and [PERSON] et al. [57] demonstrated that single band algorithms could be accepted where TSM augments with increasing reflectance. Despite that, according to [PERSON] et al. [58], composite matter in water changes the reflectance of the water body, implying variation in colors, and thus different spectral bands' combinations might be used for TSM estimation. Many studies often use a single red band (625-700 nm) for TSM estimation. Even so, it should be noted that the efficiency of these algorithms diminishes in areas with extreme sediment loads where radiometric measurements in the red band no longer correlate with increases in TSM, because a saturation effect can occur according to [PERSON] et al. [59]. Some authors such as [PERSON] et al. [60] state that, to avoid these limitations, multiband models based on the relationship of bands must be developed and applied. In our study, the data range for which the TSM estimation algorithms were obtained is 0.6 mg/L to 30 mg/L. Most of the algorithms obtained have been formulated with combinations between bands ranging from 443 to 842 nm; nevertheless, the best result was obtained using only the simple band R\({}_{705}\). [PERSON] et al. [61] use a range of TSM similar to ours, with concentrations under 20 mg/L. Their results, also using MSI-S2 imagery, obtained with a R\({}_{700}\) band algorithm present a R\({}^{2}\) 0.85, RMSE 1.55 mg/L and NRMSE 7.8 %. In this same study, an algorithm based on R\({}_{783}\)/R\({}_{492}\) combination was obtained, but in this case the concentrations were above 20 mg/L. TSM has also been estimated using the reflectance peak near 700 nm, from sensors such as MERIS, in relatively low concentrations <32 g/m\({}^{3}\) (R\({}^{2}\) > 0.81) in the studies of [PERSON] et al. [62], [PERSON] et al. [63] and [PERSON] et al. [64]. [PERSON] et al. [65], using the ratio 850/550 for highly turbid waters (<985 mg/L), show the high potential of NIR bands for TSM estimation, but exhibiting a strong non-linear correlation. For the MSI-S2, this ratio did not give significant results, which may be due to the fact that the concentrations are much lower. Several bio-optical algorithms have been created to estimate the Particulate Organic Carbon (POC) concentration in oceanic layers [66; 67; 68; 69; 70] and eutrophic lakes [71]. These algorithms were obtained for band ratios corresponding to red-to-blue (R\({}_{665}\)/R\({}_{490}\)), red-to-green (R\({}_{665}\)/R\({}_{560}\)), or blue-to-red (R\({}_{490}\)/R\({}_{665}\)) for ocean studies and for blue-to-green (R\({}_{443}\)/R\({}_{560}\) and R\({}_{490}\)/R\({}_{560}\)) ratios for lake studies. Besides, systems with an organic prevalence whose spectral signatures stem from algae concentrations sharing the pronounced absorption features and backscatter peaks described for chlorophyll. [PERSON] et al. determined in several studies [72; 73] that [Chl-\(a\)] has a peak near 700 nm and that this reflectance peak was important for measuring chlorophyll concentrations. [PERSON] et al. [74] mentioned that the scattering and absorption characteristics of [Chl-\(a\)] can also be studied when more than one band is used. Even so, with this study it has been deduced that the band that best estimates the organic fraction of TSM is R\({}_{783}\). The second-best result for estimating POM in our study, is the ratio 665/560 nm. Algorithms using ratios of reflectance in the blue (~400-500 nm) to that in the green or red (~500-700 nm) have been found to be well correlated with [Chl-\(a\)] [75]. Ratios used include MERIS bands 665/550 nm [76].