Abstract
We have investigated the influences of herbicides and mercury on the blue-green alga Spirulina platensis by analyzing the long-term behavior of S.platensis delayed fluorescence(DF). S.platensis DF was recorded as a decay curve, and change in the DF intensity with time was analyzed. The decay curve was found to be composed of two components. The first component peaked just after excitation (P1). The second component peaked at approximately 30 seconds after excitation (P2). When the alga was exposed to toxicants, the intensities of P1 (CP1) and P2 (CP2), and the time of P2 appearance (TP2) varied notably. The tested herbicides, diuron (DCMU) and simazine (CAT), increased CP1, and decreased CP2. Mercury increased TP2 and CP1, and decreased CP2. During the measurements at 30 min after the exposure, the effect of DCMU was detectable at a minimum of 0.1μg·l-1, that of CAT at 0.25μg·l-1 and that of mercury at 20μg·l-1.Furthermore, when the alga was exposed to both herbicides and mercury, the influences were combined. This study indicates that the analysis of the long-term behavior of DF of an alga may be useful in the rapid detection of toxicants in contaminated waters.
