Atrazine [BSA]

The widespread and persistent contamination of freshwater environments by low concentrations of pesticides is a growing concern worldwide. In aquatic environments, herbicide pollution is of greatest concern for phytoplankton, clue to their similarities W terrestrial plants. Through the use of Fast Repetition Rate Huorometry (FRRF) during weeklong experiments on 10 phytoplankton cultures from 4 classes and 4 natural communities, we demonstrate that PSII-inhibiting herbicides, notably atrazine that is extensively used in North America, consistently have effects on freshwater phytoplankton photophysiology at concentrations far below concentrations affecting the most sensitive species in previous studies. The parameters specific to FRRF (P, sigma, T-1, T-2, T-3) were those most sensitive to PSII inhibitors, compared to the standard fluorescence parameters derived from other fluorescence protocols such as Pulse Amplitude Modulation (PAM) fluorometry (F-0, F-m, F-v/F-m) and extracted chlorophyll a concentrations. Based on these findings, existing national environmental guidelines and standards are insufficient to adequately prevent adverse effects of atrazine and other PSII inhibiting herbicides on algal physiology in aquatic ecosystems. (C) 2019 Elsevier B.V. All rights reserved.

This study compared the removal of fifteen trace organic contaminants (TrOCs) by aerobic and anaerobic membrane bioreactors, denoted as AeMBR and AnMBR, respectively. Results show that the removal of TrOCs by either AeMBR or AnMBR was determined largely by their hydrophobicity. Almost all hydrophobic TrOCs were effectively removed (>60%) while the removal of hydrophilic compounds varied (3.6%-98.7%). AeMBR was more effective than AnMBR for the removal of all TrOCs investigated with a few exceptions. Compared to AeMBR, the removal of compounds containing nitrogen in their molecular structures (e.g. amitriptyline, carbamazepine, and atrazine) was higher by AnMBR. Of all TrOCs investigated, considerable accumulation in biosolids only occurred to amitriptyline, 4-tert-octyphenol and triclosan, particularly during AnMBR treatment. Nevertheless, biodegradation and/or biotransformation was the main mechanism for TrOC removal by both AeMBR and AnMBR. Moreover, removal of bulk organic matter indicated by total organic carbon and nitrogen was comparable for these two systems. (C) 2019 Elsevier B.V. All rights reserved.