Nitrate-N-mediated toxicological responses of Scenedesmus acutus and Daphnia pulex to cadmium, arsenic and their binary mixture (Cd/Asmix) at environmentally relevant concentrations

Olushola M. Awoyemi, Seenivasan Subbiah, Anahi Velazquez, Kelsey N. Thompson, Angela L. Peace, Gregory D. Mayer

Research output: Contribution to journalArticlepeer-review

Abstract

Several biomarkers used for ecological risk assessment have been established for single contaminant toxicity, many of which are less predictive of the influence of media and/or dietary nutrients on toxicity outcomes of contaminant mixtures. In this study, we investigate toxicological responses and life traits of Scenedesmus acutus and Daphnia pulex to heavy metals (cadmium-Cd, arsenic-As, binary mixture-Cd/Asmix) in media and diets with varied nutrient (nitrate-N) conditions (low-LN, median-MN, optimum−COMBO). Results showed that nitrate-N-mediated metal inhibitory effects on growth and productivity of primary producer (S. acutus) were significantly interactive (p < 0.05; effect size, ƞ2≤56 %). Cadmium toxicities (Cd-IC50s) in S. acutus were 1.2×, 5.3×, and 4.3× As-IC50s in LN, MN and COMBO media, respectively, while mixture (Cd/Asmix) toxicities were synergistic in MN medium and partial additivity in COMBO and LN media. Nitrate-N and metal exposure effects on S. acutus nutrient stoichiometry, metal uptake and bioaccumulation were significantly interactive (p < 0.05, ƞ2≤100 %). Moreover, survival of primary consumer (D. pulex) was significantly impaired by single and mixed dietary-metal exposures with greater effect under LN condition coupled with significant interactive effects on reproductive capacity (p < 0.05, ƞ2≤21.2 %) but not on swimming activity. We recommend that nitrate-N-mediated metal exposure effects/toxicity in bioindicator species should be considered during ecological risk assessments.

Original languageEnglish
Article number123189
JournalJournal of Hazardous Materials
Volume400
DOIs
StatePublished - Dec 5 2020

Keywords

  • Contaminant mixtures
  • Ecotoxicological risk assessment
  • Heavy metals
  • Interactive effects
  • Nitrogen availability

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