List of time-averaged concentrations (ng.L⁻¹) of herbicides found over one month's deployment at four sites in Keppel Bay and their photosystem II inhibition potential based on relative potency (potency factor^*) with respect to the reference diuron.

<p>Photosystem II equivalent concentrations (PSII-HEq) were calculated for each site by summing the PSII-HEq for individual herbicides**.</p><p>Relative potency factors of each of the herbicide with respect to the reference diuron, in terms of PSII inhibition.</p><p>PSII-HEq were calculated by summing individual PSII-HEq for each herbicide derived by multiplying the time-averaged concentration in water by the relative potency with respect to the reference herbicide diuron <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084739#pone.0084739-Kennedy2" target="_blank">[37]</a>.