Experiment 5: Effects of Platinum Group Elements (palladium and platinum) and the Rare Earth Element cerium on terrestrial plant pollen: quality and germination
Metals, including some PGEs and REEs, seem to greatly affect pollen formation, viability and germination. Exposure to PGEs occurs largely via aerial deposition along roadsides as well as in long range transport. Plant pollen is thus extremely likely to come into contact with PGEs, including palladium (Pd) and platinum (Pt), as well as cerium (Ce), via aerial emissions. The aim of this study was to determine whether Pd, Pt and Ce affect pollen growth and development in terrestrial plants. It was hypothesized that malformations and inhibitory effects (reduced viability) on pollen would occur if pollen was exposed to these metals. Four species were selected which belonged to four different plant families: Trifolium pratense L. (Fabaceae), Brassica juncea (L.) Czernajew (Brassicaceae), Centaurea cyanus L. (Asteraceae) and Viola arvensis Murray (Violaceae). The experiment was conducted in NWRC greenhouses of Environment and Climate Change Canada. Seeds of each species were sown in a soil mixture and pollen grains were collected at maturity. The medium used for pollen germination differed between species. The basic medium comprised sucrose, boric acid and calcium nitrate in various concentrations as well as polyethylene glycol. Other compounds were added depending on the species: yeast extract, magnesium sulfate, potassium nitrate and/or iron sulfate. Pollen grains freshly collected were mixed with the medium on glass slides. In total, seven doses x six replicates were assessed. After four hour incubation, pollen grains were rated as germinated or not germinated. Pollen germination and tube length were measured on a minimum of 20 pollen grains per drop (replicate). Results showed that all species were affected by Ce exposure to different degrees. Percent germination was observed to decrease in a dose-response manner with increasing Ce concentrations. Consistent effects were observed in all trials with T. pratense and in three trials with V. arvensis. These two species germinated readily when exposed to their respective medium in control replicates. Pollen germination of C. cyanus appeared to also be a sensitive endpoint although large variability in the results was detected in all trials. As observed for C. cyanus, effect on pollen germination was only recorded in one trial for B. juncea, with the effect only present at the highest evaluated dose (24.3 mg Ce L-1). Effects on overall pollen germination in C. cyanus and B. juncea, however, remain difficult to interpret due to the overall low germination rates observed for these species. In contrast, pollen tube length provided more consistent results, and, with the exception for T. pratense, proved to be a more sensitive endpoint for several species tested with Ce. In contrast, Pd only affected T. pratense. Pd exposure did not inhibit pollen germination in any of the species tested. However, Pd did have a negative effect on pollen tube length in T. pratense in two trials. Although only EC10 and EC25 could be determined, Pd appeared to be quite toxic to the species. With regards to Pt, significant effects were found to be erratic in all experiments.
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- File Identifier
- 55a9c99f-58cf-42d6-8394-56cd76b1a56d XML
- Date Stamp
- 2021-05-12T06:01:58
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eng; CAN
- Character set
- UTF8
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- Dataset
http://ec.gc.ca
Data identification
- Date (Publication)
- 2018-06-21
- Date (Creation)
- 2018-06-21
- Status
- Completed
- Metadata language
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eng; CAN
- Character set
- UTF8
- Topic category
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- Environment
- Maintenance and Update Frequency
- As needed
- Spatial representation type
- Vector
6139980458
Keywords
- Theme
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Metals, platinum. palladium, cerium, pollen, terrestrial plants, toxicity
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Substance
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Government of Canada Core Subject Thesaurus
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Toxicology
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ECCC Information Category EN
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Nature and Biodiversity - Contaminants
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Business Functions
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Assess Toxicity, Manage and Monitor for Environmental Presence of Hazardous Substances and Waste
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Assess Toxicity of Substance
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Geography
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National (CA)
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external.theme.EC_Branch
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Science and Technology Branch
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external.theme.EC_Directorate
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Wildlife and Landscape Science
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external.theme.GC_Security_Level
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Confidential
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Open Government Licence - Canada ( http://open.canada.ca/en/open-government-licence-canada )
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- License
- Use Constraints
- License
- Begin Date
- 2018-06-21
- End Date
- 2018-06-21
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- Reference system identifier
- EPSG / 4326 / Inconnue
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CSV
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CSV
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CSV
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CSV
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http://ec.gc.ca
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