Comparative effects of the herbicides chlortoluron and mesotrione on freshwater microalgae

Abstract

Extensive use of herbicides in agriculture is accompanied by the risk of environmental contamination of aquatic ecosystems. The present study shows the effects of the herbicides chlortoluron and mesotrione on three microalgae species: two chlorophyceae (Pediastrum tetras, Ankistrodesmus fusiformis) and one diatom (Amphora coffeaeformis). The authors calculated the IC50 for one chlorophyceae and the diatom. The order of toxicity (median inhibitory concentration [IC50]) for mesotrione was A. coffeaeformis (13.1 mg/L) > A. fusiformis (56.1 mg/L) and A. fusiformis (0.05 mg/L) > A. coffeaeformis (0.08 mg/L) for chlortoluron. The impact of herbicides applied at 0.2 mg/L was then examined in Erlenmeyer flasks by monitoring for growth, pigment content, and metabolic activity. Algal responses varied widely according to species and herbicide. For example, chlortoluron showed a significant inhibitory effect on the growth of A. coffeaeformis, whereas mesotrione induced an increase in cellular density in A. fusiformis. Other cellular parameters, such as pigment content in P. tetras, were stimulated by both herbicides. The results obtained confirmed that microalgae cultures are clearly affected by acute and chronic exposition to herbicides. Further monitoring should be carried out in the field to assess the impact of sublethal levels of toxicity and the growth-enhancing effects of mesotrione and chlortoluron on natural algae communities.

Potential of TiO2 with Various Au Nanoparticles for Catalyzing Mesotrione Removal from Wastewaters under Sunlight

“…Besides good properties of mesotrione for weed control, non-target organisms are exposed by additional toxic and harmful effects. Because of the low sorption of mesotrione in the soil, it has a tendency to leach to the groundwater during corn cultivation [ 2 ], where it causes negative consequences on the aquatic ecosystem [ 3 ]. In addition, toxic influence on Tetrahymena pyriformis nonspecific esterase activities Vibrio fischeri metabolism and may cause infestation of some sea life [ 4 ].…”

Subchronic exposure to high-density polyethylene microplastics alone or in combination with chlortoluron significantly affected valve activity and daily growth of the Pacific oyster, Crassostrea gigas

“…Valiente Moro et al (2012) reported an IC 50 (half-maximum inhibitory concentration) of 50 µg.L -1 on the freshwater phytoplankton Ankistrodesmus fusiformis. Although this concentration is higher than those commonly found in the Pertuis Charentais, it is quite close to the maximum concentrations detected in some European rivers.…”

“…Chlortoluron that belongs to substituted urea family is one of the most commonly used herbicides in wheat and barley crops. Chlortoluron inhibits photosynthesis and affects phytoplankton (Valiente Moro et al, 2012). In 2017, a maximum value of 0.18 μg.L -1 was detected at the mouth of a river (surface water) flowing into the Pertuis Charentais (Leonard, 2017).…”

Sustainable Wastewater Management: Is it Possible to Regulate Micropollution in the Future by Learning from the Past? A Policy Analysis

“…52,100 tons of organic pesticides, equating to more than 500 different active substances, were used in France in 2009 [50]. In 2000, the nation used 5033 tons of phenylurea herbicides, including chlortoluron, one of the most popular herbicides due to its long half-life in soil (30-40 days).…”