The effect of oil sands process-affected water and model naphthenic acids on photosynthesis and growth in Emiliania huxleyi and Chlorella vulgaris

Abstract

Naphthenic acids (NAs) are among the most toxic organic pollutants present in oil sands process waters (OSPW) and enter marine and freshwater environments through natural and anthropogenic sources. We investigated the effects of the acid extractable organic (AEO) fraction of OSPW and individual surrogate NAs, on maximum photosynthetic efficiency of photosystem II (PSII) (FV/FM) and cell growth in Emiliania huxleyi and Chlorella vulgaris as representative marine and freshwater phytoplankton. Whilst FV/FM in E. huxleyi and C. vulgaris was not inhibited by AEO, exposure to two surrogate NAs: (4'-n-butylphenyl)-4-butanoic acid (n-BPBA) and (4'-tert-butylphenyl)-4-butanoic acid (tert-BPBA), caused complete inhibition of FV/FM in E. huxleyi (≥10 mg L(-1)n-BPBA; ≥50 mg L(-1)tert-BPBA) but not in C. vulgaris. Growth rates and cell abundances in E. huxleyi were also reduced when exposed to ≥10 mg L(-1)n- and tert-BPBA; however, higher concentrations of n- and tert-BPBA (100 mg L(-1)) were required to reduce cell growth in C. vulgaris. AEO at ≥10 mg L(-1) stimulated E. huxleyi growth rate (p ≤ 0.002), yet had no apparent effect on C. vulgaris. In conclusion, E. huxleyi was generally more sensitive to NAs than C. vulgaris. This report provides a better understanding of the physiological responses of phytoplankton to NAs which will enable improved monitoring of NA pollution in aquatic ecosystems in the future.

Nanoholes Regulate the Phytotoxicity of Single-Layer Molybdenum Disulfide

“…The cell density ( N t ) was monitored at the adsorption peak of C. vulgaris 689 nm using a UV–vis spectrophotometer (TU-1900, Purkinje General, China). , A correlation curve between N t and A 689 was depicted in Figure S1. The regression equation for the correlation of N t ( x × 10 6 cells mL –1 ) with A 689 ( y ) was calculated to be y = 0.180 x – 0.034 ( p < 0.05, R 2 = 0.9920).…”

Differential protein expression during growth on model and commercial mixtures of naphthenic acids in Pseudomonas fluorescens Pf‐5

“…There are still no approved strategies to treat and safely release OSPW; thus, it is contained in large tailings ponds which cause considerable environmental concern (Giesy et al, 2010 ). One of the major challenges for reclaiming these ponds is the presence of naphthenic acids (NAs) which are the main toxic components of OSPW and demonstrate both acute and chronic toxicity to a variety of aquatic organisms (Beddow et al, 2016 ; Frank et al, 2009 ; Headley & McMartin, 2004 ; Morandi et al, 2015 ). NAs are also highly persistent under field conditions and a major long‐term strategy for remediation is to age the water in end‐pit lakes, but this strategy is highly uncertain and may take decades (Gosselin et al, 2010 ).…”

Environmental Transformations and Algal Toxicity of Single-Layer Molybdenum Disulfide Regulated by Humic Acid

“…The C. vulgaris culture always divided into the stationary phase in 96 h and then gradually died afterward. 30 Therefore, the inhibition effects of SLMoS 2 and SLMoS 2 −HA on cell growth were evaluated by identifying the cell numbers using flow cytometry (FCM) at 24, 48, 72, and 96 h. Moreover, chlorophyll a was measured using a UV−vis spectrophotometer (T90, Purkinje General, China) (details in the Supporting Information). The cell permeability and mitochondrial membrane potential were determined using fluorescein diacetate (FDA) and 5,5′,6,6′-tetrachloro-1,1′,3,3′tetraethylbenzimidazolylcarbocyanine iodide (JC−1), respectively (details in the Supporting Information).…”