Detection of chlorophyll fluorescence as a rapid alert of eutrophic water

Abstract

Abstract An in-situ detection of chlorophyll fluorescence was used in an innovative manner to detect eutrophic water, and the results were compared with the Carlson's Trophic State Index (CTSI) indicators. Eutrophication was due to climate warming and anthropogenic activities. The turbidity and chromaticity showed a strong linear relationship (R2 = 0.85) of the Bi Lake in Taipei city. Both the swimming area and the bridge are popular with the general public and had the worst turbidity (35.80–44.00 NTU) and chromaticity (495.37–552.27 Pt). The CTSI had a stronger linear relationship with the phycocyanin (PC) concentration (R2 = 0.605) than with any other three CTSI factors like chlorophyll-a concentration, total phosphorus (TP) concentration, and transparency. The TP pollution had a potential to cause an increase in PC concentration found in this study (R2 = 0.86). The absorbances of the water samples represented that the environment is PC (cyanobacteria) dominant in winter. The PC concentration in Bi Lake ranged from 75.55 to 80.24 μg/L and was higher with lower water temperature. Measurement of in-situ chlorophyll fluorescence is similar to lab-scale spectrophotometer (R2>0.92). The real-time detection of PC concentration could be the basis of a rapid alert system for biological threats to waters.