MODELLING ALGAL TOXINS AND OFF-FLAVORS IN TROPICAL WATERS

Abstract

Algal blooms arising from eutrophication can sometimes come with problematic cyanotoxin and off-flavour compounds. This study focuses on modelling cyanotoxins (microcystin and cylindrospermopsin) and off-flavour (geosmin) and understanding their occurrence in local tropical waters. First, a model was developed to predict microcystins from cyanobacteria in a local reservoir. Inclusion of a nitrogen-phosphorus factor in the model improved the model performance, but other modifications such as non-constitutive microcystin production were also suggested. The model was subsequently used to simulate microcystin in a local reservoir to identify its most influential factors, which was irradiation. However, microcystin concentrations depended heavily on the producer occurrence, but was unaffected by grazers or phages. For geosmin and cylindrospermopsin, multi-linear regression models were built as they were less studied. Their predictors suggested they were mainly produced by actinobacteria and by cyanobacteria other than Raphidiopsis, respectively, in that reservoir, and factors like chloride could be further studied.