Feasibility and assessment of the phytoremediation potential of green microalga and duckweed for zeta-cypermethrin removal

Abstract

Insecticides are among the most harmful chemicals to the environment. In the present study, the effect of synthetic pyrethroid insecticide zeta-cypermethrin, which is commonly used in fighting hazelnut weevil (Curculio nucum L.), was examined on the growth and bioremediation of aquatic photosynthetic organisms (Chlamydomonas reinhardtii P.A. Dangeard and Lemna minor L.). Growth performance analysis, photosynthetic pigment analysis, and residue pesticide analysis were conducted with liquid chromatography-mass/mass spectrometer (LC-MS/MS). The changes in surface morphological structure of C. reinhardtii and L. minor were examined with a scanning electron microscopy (SEM). Low concentration zeta- cypermethrin (150 mu g/L) applied to the species created a nutrient effect (hormesis). However, high concentrations (300-600 mu g/L) showed a toxic effect and inhibited growth. The rate of decomposition in species was found to be correlated with the pesticide concentrations applied to the environment. In LC-MS/MS results, the highest pesticide absorbance value was found in C. reinhardtii at the 96th h in 300 mu g/L test medium (98.2%). In L. minor, these rates were recorded lower (35.4%-95.9%). Similarly, in high concentration pesticide application (600 mu g/L), pesticide removing capacity of micro green algae was higher when compared with duckweed (92.8%-98.3%). It was found that some of the pesticide absorbed in the first time frame of the bioassay was released to the environment. Especially in the test groups which were given moderate and high concentrations of pesticide, pesticide release profile of L. minor was more obvious. As a result of the study, it was found that microalgae were more effective agents than duckweed in removing zeta-cypermethrin from water.