Effects of the interaction between nutrient concentration and DIN:SRP ratio on geosmin production by freshwater biofilms

Driving Factors of Geosmin Appearance in a Mediterranean River Basin: The Ter River Case

“…Once these cyanobacteria reached the stationary phase, there was a rapid decrease in intracellular concentration with a corresponding rapid increase of geosmin release, indicating that cell lysis and decomposition of geosmin producers may result in large spikes of these compounds in water supplies. Similar results were observed by Cai et al (2017) ; Alghanmi et al (2018) , and Espinosa et al (2021) , supporting the idea that the majority of geosmin is normally retained with cyanobacterial cells during their growth, and release to the medium occur as a consequence of lysis and cellular decomposition. Different studies have pointed out that, depending on the cyanobacterial strain, the growth phase differs.…”

“…Similar results were observed in this field study, where higher nutrient concentration may have generated favorable conditions for the cyanobacterial development within biofilm communities (0.91 ± 0.58 μg/cm 2 in T4 compared with 0.33 ± 0.44 μg/cm 2 in T1, mean annual value). Some studies have described that a high nitrogen concentration is necessary for cyanobacteria blooms to occur (>0.8 mgTN/L, Xu et al, 2015 ; ≈0.1 mgN-NH 4 + /L, ≈1.1 mgN-NO 3 – /L, Espinosa et al, 2021 ). Perkins et al (2019) pointed out that the ammonium concentration was key for stimulating cyanobacteria development and production of T&O compounds, specifically revealing that metabolites were associated with high ammonium relative to nitrate.…”

“…The change in the physicochemical conditions at the different sampling sites and seasons could explain the change in the relative importance of the parameters included in the models developed at different time lags. As shown in Figure 5, nitrate concentration and temperature are more relevant in predicting geosmin between lags 5 and 10 (1-2 and a half months in advance), which could indicate the need for high basal nitrate conditions (Xu et al, 2015;Espinosa et al, 2021). However, for a geosmin episode to occur, it seems that a gradual increase in the phosphorus concentration, whose maximum importance as a geosmin driver within the model is reached in lag 2-w, is needed to generate conditions that would favor the development of cyanobacteria biomass.…”

“…Bottles were stored at 4 • C in dark conditions until analysis, which was performed within 48 h after collection to avoid degradation and volatilization. The protocol followed for geosmin analysis in water was described in Espinosa et al (2021). Briefly, to analyze geosmin concentration, 50 ml of each water sample and 10 g of NaCl were added to a 100-ml opaque reaction vial and heated at 60 • C for 25 min in agitation to favor geosmin volatilization.…”

Data_Sheet_1.PDF

“…Similar results were observed in this field study, where higher nutrient concentration may have generated favorable conditions for the cyanobacterial development within biofilm communities (0.91 ± 0.58 µg/cm 2 in T4 compared with 0.33 ± 0.44 µg/cm 2 in T1, mean annual value). Some studies have described that a high nitrogen concentration is necessary for cyanobacteria blooms to occur (>0.8 mgTN/L, Xu et al, 2015 Espinosa et al, 2021). Perkins et al (2019) pointed out that the ammonium concentration was key for stimulating cyanobacteria development and production of T&O compounds, specifically revealing that metabolites were associated with high ammonium relative to nitrate.…”