Overview
This study established acute and chronic toxicity thresholds for palladium in Daphnia magna and characterized how dissolved organic carbon (DOC) modifies Pd bioavailability and toxicity. The 48-hour LC50 was 52 ug/L and the chronic 15-day EC50 for offspring viability was 1 ug/L, 52 times lower than the acute threshold. DOC reduced Pd bioaccumulation by 30-40% and eliminated acute toxicity at 1 mg C/L and above.
Key numbers
- Acute 48h LC50: 52 +/- 2 ug/L (measured concentrations 2-110 ug/L)
- Acute LC10: 33 +/- 3 ug/L
- With DOC at 0.8 mg C/L: acute LC50 = 74 +/- 1 ug/L
- DOC 1-8 mg C/L: no Daphnia mortality observed at any concentration tested
- Chronic 15-day EC50 for offspring viability: 1 +/- 0.1 ug/L
- Chronic EC50 for total broods per female: 7 +/- 2 ug/L
- Chronic parental LC50: 14 +/- 2 ug/L
- Pd bioaccumulation reduced 30-40% with increasing DOC (up to 50% at highest DOC)
- Environmental Pd in Quebec urban rivers: 0.085-0.29 ng/L (well below chronic EC50)
Methods (brief)
Standard OECD Daphnia magna acute (48h) and chronic (15-day) toxicity protocols. Pd as PdCl2. DOC manipulation with humic acid at 0, 0.8, 1, 2, 5, and 8 mg C/L. Offspring counts, brood number, and adult survival as chronic endpoints. Pd bioaccumulation measured by ICP-MS on tissue digests. Environmental Pd concentrations compared with published Quebec river monitoring data.
Implications
This page makes the source discoverable for palladium evidence routing. Provides standard aquatic ecotoxicological thresholds for Pd in a cladoceran model organism, with DOC-modulation data showing that natural organic matter substantially reduces Pd toxicity in realistic freshwater conditions.
Related evidence
Update history
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