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Lead toxicity to Lemna minor predicted using a metal speciation chemistry approach
Author(s) -
Antunes Paula M.C.,
Kreager Nancy J.
Publication year - 2014
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.2688
Subject(s) - chemistry , environmental chemistry , biotic ligand model , genetic algorithm , lemna minor , dissolved organic carbon , metal , alkalinity , aqueous solution , solubility , water quality , hard water , toxicity , bioavailability , macrophyte , nuclear chemistry , aquatic plant , biology , ecology , bioinformatics , organic chemistry
In the present study, predictive measures for Pb toxicity and Lemna minor were developed from bioassays with 7 surface waters having varied chemistries (0.5–12.5 mg/L dissolved organic carbon, pH of 5.4–8.3, and water hardness of 8–266 mg/L CaCO 3 ). As expected based on water quality, 10%, 20%, and 50% inhibitory concentration (IC10, IC20, and IC50, respectively) values expressed as percent net root elongation (%NRE) varied widely (e.g., IC20s ranging from 306 nM to >6920 nM total dissolved Pb), with unbounded values limited by Pb solubility. In considering chemical speciation, %NRE variability was better explained when both Pb hydroxides and the free lead ion were defined as bioavailable (i.e., f {OH} ) and colloidal Fe(III)(OH) 3 precipitates were permitted to form and sorb metals (using FeO x as the binding phase). Although cause and effect could not be established because of covariance with alkalinity ( p = 0.08), water hardness correlated strongly ( r 2 = 0.998, p < 0.0001) with the concentration of total Pb in true solution ([Pb] T_True solution ). Using these correlations as the basis for predictions (i.e., [Pb] T_True solution vs water hardness and %NRE vs f {OH} ), IC20 and IC50 values produced were within a factor of 2.9 times and 2.2 times those measured, respectively. The results provide much needed effect data for L. minor and highlight the importance of chemical speciation in Pb‐based risk assessments for aquatic macrophytes. Environ Toxicol Chem 2014;33:2225–2233 . © 2014 SETAC