Uptake and bioconcentration of atrazine by selected freshwater algae

Abstract

Atrazine bioconcentration and uptake were determined for eight freshwater green algae and diatoms. Atrazine uptake was extremely rapid in all species examined, with nearly 90% of total uptake occurring within the first hour of exposure. Within each division, different species had different bioconcentration capacities, although the accumulation of atrazine was consistently higher in green algae (5.43–12.73 ng/mg) than in diatoms (0.33–1.69 ng/mg). Atrazine concentrations in the algal cells were much higher than in the medium, although the total amount of atrazine taken up by algae was small relative to the total atrazine in solution (1–3%). The ability of algal cells to accumulate atrazine was highly correlated with algal cell biovolume and surface area, and a strong relationship was observed between sensitivity to atrazine and bioconcentration, cell biovolume, and surface area. In general, higher bioconcentration factors were associated with increased atrazine sensitivity.

Comparative Sensitivity of Freshwater Algae to Atrazine

“…Tang et al (1998a) observed a high correlation between cell volume and atrazine toxicity for four species of green algae and four diatoms. A similar pattern was evident in the present study (i.e., smaller cells were generally more susceptible than larger cells), but the relationship was not signifi cant when a larger number of algal divisions are included.…”

“…Tang et al (1998b) found differences among algal species in the activity of glutathione-s-transferase, an enzyme associated with atrazine detoxifi cation in vascular plants, yet the different rates of metabolism were not suffi cient to explain the differential responses of the algae to atrazine. Tang et al (1998a) found that the uptake of atrazine by green algae was signifi cantly greater than that of diatoms, and that green algae had greater bioconcentration factors as well. However, in that study, the strongest predictor of algal sensitivity was cell biovolume.…”

Biosorption Potential of the Microchlorophyte Chlorella vulgaris for Some Pesticides

“…Concerning atrazine, Tang found that green algae as Chlamydomonas sp., Chlorella sp., Pediastrum sp., and S. quadricauda could biosorbe more atrazine compared with diatoms (Cyclotella gamma, Cyclotella meneghiniana, Synedra acus and Synedra radians) [31]. The differential selectivity of algae species to atrazine can be attributed to their morphology, Cytology, physiology, phylogenetic, studied atrazine toxicity, accumulation and biodegradation in the microchlorophyte Chlamydomonas mexicana which exhibited accumulation and biodegradation potential resulting in 14-36% atrazine degradation at 10-100 μg L -1 .…”

Temperature and Light Modulation of Herbicide Toxicity on Algal and Cyanobacterial Physiology

“…Similarly, Tasmin et al (2014a,b) observed that rising water temperatures (from 10 to 30 • C) reduced the toxicity of diuron (up to 32 µg l −1 ) on the green algae Pseudokirchneriella subcapitata. This could be due to the smaller biovolumes of these organisms compared to the other species and to their decreased herbicide uptake rates (Tang et al, 1998;Larras et al, 2013). As seen with herbicides, decreased biovolumes will also limit nutrient uptake in diatoms-so that additional tolerance mechanisms involving better nutrient recycling, or specialized mechanisms of nutrient uptake with herbicide avoidance, may also be involved.…”