Apparent toxicity resulting from the sequestering of nutrient trace metals during standard Selenastrum capricornutum toxicity tests

Ward, Timothy J.; Rausina, Gary A.; Stonebraker, P.M.; Robinson, William E.

doi:10.1016/s0166-445x(01)00259-4

Cited by 15 publications

(6 citation statements)

References 18 publications

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“…In addition, live cells were shown to be able to remove and degrade the PAHs continuously. Suppression of microalgal growth often was observed in the presence of different contaminants [34,35]. Baun et al [36] reported that growth of S. capricornutum was totally inhibited in a soil mixture contaminated by PAHs at a concentration of 0.16 g soil/L medium.…”

Section: Discussionmentioning

confidence: 99%

Removal and biodegradation of polycyclic aromatic hydrocarbons by Selenastrum capricornutum

Chan

Luan

Wong

et al. 2006

Enviro Toxic and Chemistry

150

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The removal and degradation of a mixture of polycyclic aromatic hydrocarbons (PAHs), namely phenanthrene (PHE), fluoranthene (FLA), and pyrene (PYR), by a green microalgal species, Selenastrum capricornutum, at different initial cell densities were studied. The PAH removal efficiency increased with the initial cell density, and 96% of PHE, 100% of FLA, and 100% of PYR in the medium were removed by live S. capricornutum at the density of 1 x 10(7) cells/ml in 4 d, whereas less than 50% of PAHs were removed at the lowest cell density (5 x 10(4) cells/ml) in 7 d. The removal mechanisms included initial adsorption onto the cell walls of both live and dead cells, and the adsorbed PAHs were then absorbed and degraded in live cells only. Among different PAHs in a mixture, irrespective of whether they were added to medium at the same or different concentrations, the removal preference by live S. capricornutum was in the descending order of PYR > FLA > PHE, whereas the biodegradation rates followed the descending order of FLA > PYR > PHE. Initial findings regarding PAH metabolites revealed that PHE was converted into four different monohydroxyphenanthrenes and two dihydroxyphenanthrenes, whereas FLA and PYR were converted into three hydroxylated derivatives through the monooxygenase pathway. The presence of dihydroxylated PAHs suggested that the dioxygenase pathway also might have taken place at the same time.

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Section: Discussionmentioning

confidence: 99%

Removal and biodegradation of polycyclic aromatic hydrocarbons by Selenastrum capricornutum

Chan

Luan

Wong

et al. 2006

Enviro Toxic and Chemistry

150

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“…Selenastrum capricornutum is a relatively small (length, ∼10 μm), crescent‐shaped, unicellular green alga. After attempting experiments with various algae (other greens, cryptophytes, and diatoms), S. capricornutum was chosen because of its ease of growth in the laboratory, previous use in other studies [2,3,8,17], presence in natural samples, edibility by zooplankton, and use as a U.S. Environmental Protection Agency test organism [18]. Algal cultures were grown axenically in 500‐ml, acid‐leached, polycarbonate Erlenmeyer flasks (Corning, Acton, MA, USA), which were covered with two‐position screw caps.…”

Section: Methodsmentioning

confidence: 99%

Speciation of aqueous methylmercury influences uptake by a freshwater alga (Selenastrum capricornutum)

Gorski

Armstrong

Hurley

et al. 2006

Enviro Toxic and Chemistry

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Uptake of methylmercury (MeHg) by the alga Selenastrum capricornutum was measured in freshwater batch culture bioassays. The concentration of MeHg in the alga increased rapidly (within 15 min), reached a maximum by 6 h, and then declined because of growth dilution. The alga's rapid growth rate (doubling time, approximately 10 h) contributed to the importance of growth dilution. Conditional first-order rate constants were calculated for uptake (k1 = 6.95 x 10(-9) L/cell/h) and growth (kG = 0.07/h). A competitive synthetic ligand, disodium ethylenediaminetetra-acetate, formed strong complexes with MeHg and reduced MeHg uptake, consistent with the biotic ligand model. A conditional equilibrium formation constant (K) for the MeHg-algae complex was estimated to be approximately 10(16) and was used to model the influence of natural ligands on MeHg bioavailability. Model results suggested MeHg would be most bioavailable at concentrations of dissolved organic matter (DOM) less than 10 mg/L and increasingly unavailable at higher DOM concentrations for the specific humic acid modeled. Similarly, at molar concentrations of sulfide (and, possibly, metal-sulfide clusters) equal to approximately half the MeHg concentration, MeHg was predicted to be unavailable to algae because of the formation of strong 2:1 MeHg-sulfide complexes.

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“…As to their growth-inhibiting effect, various tests (Table IV) demonstrated that individual algae species may be growth-inhibited by comparatively low aminopolycarboxylate concentrations, about 1 mg/L. However, it must be taken into account that algae toxicity tests with complexing agents and the evaluation of their results are quite problematic in general (Ward et al, 2002). The artificial culture media that are utilized in standardized algae tests inherently contain low amounts of EDTA in order to solubilize essential trace elements like iron.…”

Section: Impact Of Aminopolycarboxylates On Aquatic Organismsmentioning

confidence: 99%

“…At concentration ratios observed in the environment, the harmful impact of aminopolycarboxylates on algae is rather improbable. Consequently, the results obtained in common laboratory algal tests cannot be used for the ecotoxicological evaluation of aminopolycarboxylates because conditions in these test systems are not environmentally compatible (BUA, 1996;Ward et al, 2002). Sillanpää and Oikari, 1996 Along with causing the trace element deficiency already described for other organisms, bacteria can be seriously damaged by aminopolycarboxylates extracting calcium and magnesium ions from the outer cell membrane, initiating subsequent loss of lipopolysaccharides (Brüggenthies, 1996;Sillanpää, 1997).…”

Section: Impact Of Aminopolycarboxylates On Aquatic Organismsmentioning

confidence: 99%

Impact of aminopolycarboxylates on aquatic organisms and eutrophication: Overview of available data

Schmidt

Brauch

2004

Environmental Toxicology

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Aminopolycarboxylic acids, which include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), 1,3-propylenediaminetetraacetic acid (1,3-PDTA), beta-alaninediacetic acid (beta-ADA), and methylglycinediacetic acid (MGDA), constitute a class of complexing agents that occur in a wide range of domestic products and that are used intensively as metal sequestrants in several industrial applications. Because they are highly polar and partially nondegradable, aminopolycarboxylates are released into the aquatic environment in significant quantities, mainly via wastewater. The historical and current use of aminopolycarboxylates and their ubiquitous presence in surface waters prompted many studies about their possibly detrimental impact on aquatic organisms. This review summarizes the available data and information on the eutrophication potential and toxicity of aminopolycarboxylates to a multitude of aquatic organisms including vertebrates, invertebrates, algae, bacteria, and protozoa. This article also addresses how the ecotoxic effects of aminopolycarboxylates are dependent on their speciation, that is, on their presence in a free or a metal-complexed form.

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Apparent toxicity resulting from the sequestering of nutrient trace metals during standard Selenastrum capricornutum toxicity tests

Cited by 15 publications

References 18 publications

Removal and biodegradation of polycyclic aromatic hydrocarbons by Selenastrum capricornutum

Removal and biodegradation of polycyclic aromatic hydrocarbons by Selenastrum capricornutum

Speciation of aqueous methylmercury influences uptake by a freshwater alga (Selenastrum capricornutum)

Impact of aminopolycarboxylates on aquatic organisms and eutrophication: Overview of available data

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