Experiment 3: Effects of Rare Earth Element mixtures (lanthanum, neodymium, cerium) on terrestrial crops and native plants: uptake, accumulation, soil pH and calcium

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The objective of this experiment was to expose plants to a mixture of the three most common and widely used Rare Earth Elements (REEs) in soils: lanthanum (La), neodymium (Nd) and cerium (Ce). It was hypothesized that plant sensitivity to La, Nd and Ce would be additive, and would increase with overall soil REE concentration. In addition, it was hypothesized that REE uptake would be similar for all three REEs (measured concentrations in plants would be equal) if REE soil concentrations were equal (La = Nd = Ce). Deviations in uptake would indicate potential higher risks of one REE over the others. Nd, Ce, and La were tested in soil mixture with doses based on the previously identified IC25 and IC50 values for native plant species (see Experiments 1 and 2). Doses were equal for all REEs in a given dose (i.e. 100 mg/kg Nd, Ce, and La), and followed a geometric progression. Due to the presumed influence of pH and calcium (Ca) on bioavailability and uptake, two soil pH levels (one acidic, one closer to neutral) and two Ca levels were also be tested. Two species were tested: the native common milkweed, Asclepias syriaca as well as the crop tomato, Solanum lycopersicum var. Beefsteak. The full experimental set-up was: 2 soil pH levels x 2 Ca concentrations x 4 REE doses (including controls) x 2 plant species x 6 replicates = 192 pots. The experiment was conducted in NWRC greenhouses of Environment and Climate Change Canada with plants tested individually in pots. Measured endpoints included germination percent and rates, aboveground and below ground biomass. In addition, to address plant accumulation rates, tissue concentrations (roots and shoots) of the REEs, as well as calcium, were measured. Results indicated no obvious effect of treatment on the overall number of germinating seeds of A. syriaca or S. lycopersicum. Speed of germination of both species was found to be significantly affected by the soil treatments. For A. syriaca, a marginally significant main effect of soil REE dose was found but no main effects for soil pH or soil Ca; however, there was a significant soil pH x soil Ca interaction. Speed of germination of S. lycopersicum was found to be significantly affected by both soil pH and soil total REE concentrations but there was no main effect of soil Ca levels, and no significant interactions were identified. Effects of soil parameters (pH, Ca, and REE) on A. syriaca and S. lycopersicum root and shoot biomass were complex. In general, a reduction in biomass was observed at high REE doses but there were multiple interactions with soil pH and Ca. The measured concentrations of each individual REE in plant tissues (both roots and shoots) were found to consistently increase with increasing soil REE dose within a given soil pH, soil Ca treatment. For all treatments, the measured concentration of a given REE was always greater in the roots than in the corresponding shoots. Measured REE soil concentrations tended to follow a consistent pattern of [Ce] > [Nd] > [La] for all soil treatment levels (soil pH, soil Ca, soil REE). However, results for the REE-dosed soils across all soil pH x soil Ca treatments consistently followed a pattern of [La] > [Ce] > [Nd] for both tissues in both species with the only exceptions found for the roots of both A. syriaca and S. lycopersicum in the high soil pH, low Ca, 150 mg REE kg-1 treatment ([Ce] > [La] > [Nd]). The overall result for REE-dosed soils appears to indicate that La may be more readily taken up by plants, followed by Ce and then Nd. All REE control soils were found to contain background levels of the three tested REEs: La (3.16 ± 0.01 mg kg-1 dry soil), Ce 6.94 ± 0.21 mg kg-1 dry soil), and Nd (3.91 ± 0.10 mg kg-1 dry soil). REE recovery rates, calculated as: (measured REE soil concentration – background level concentration)/nominal REE soil concentration, spanned from 93-117%, 98-124%, and 96-127% for La, Ce, and Nd respectively.

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File Identifier
File Identifier
60f7aa51-5d3f-48ee-9f8a-cfcb3af77a85 XML
Date Stamp
Date Stamp
2021-05-12T06:01:50
Metadata language

eng; CAN
Character set
Character set
UTF8
UTF8
Hierarchy Level
Hierarchy Level
Dataset
Dataset
Author
Author
 
Gouvernement du Canada; Environnement et Changement climatique Canada
 - Environment and Climate Change Canada (
Centre de renseignements à la population
)

200 Sacré-Coeur Blvd, Édifice Fontaine 12e étage
, Gatineau,
Québec
, K1A 0H3,
1-800-668-6767

http://ec.gc.ca
 

Data identification

Title

Experiment 3: Effects of Rare Earth Element mixtures (lanthanum, neodymium, cerium) on terrestrial crops and native plants: uptake, accumulation, soil pH and calcium

Date (Creation)
Date (Creation)
2018-06-14
Date (Publication)
Date (Publication)
2018-06-14
Status
Status
Completed
Completed
Metadata language

eng; CAN
Character set
Character set
UTF8
UTF8
Topic category
Topic category
  • Environment
    Environment
Maintenance and Update Frequency
Maintenance and Update Frequency
As needed
As needed
Spatial representation type
Spatial representation type
Vector
Vector
Author
Author
 
Gouvernement du Canada; Environnement et Changement climatique Canada; S&T/SFP/DESF
 - Céline Boutin (
Chercheure scientifique
)

1125 Colonel By Drive, NWRC building, Carleton University
, Ottawa,
Ontario
, K1A0H3,
Canada (le)
613-998-0493

613-998-0458

Keywords

Theme
Theme

  • Terres rares, lanthanum, neodymium, cerium, métaux, phytotoxicité

Thésaurus des sujets de base du gouvernement du Canada

  • Toxicologie

ECCC Information Category FR

  • Nature et biodiversité - contaminants

Fonctions de l'entreprise

  • Évaluer la toxicité de la présence dans l'environnement des substances et des déchets dangereux, les gérer et les surveiller

  • Évaluer la toxicité de la substance

Portée Géographique

  • National (CA)

  • National (CA)

local.theme.external.theme.EC_Branch

  • Direction générale des sciences et de la technologie

local.theme.external.theme.EC_Directorate

  • Sciences de la faune et du paysage

local.theme.external.theme.GC_Security_Level

  • Confidentiel
 
Use Limitation

Licence du gouvernement ouvert - Canada ( http://ouvert.canada.ca/fr/licence-du-gouvernement-ouvert-canada)

Access Constraints
Access Constraints
License
License
Use Constraints
Use Constraints
License
License
Begin Date
2018-06-14
End Date
2018-12-18

Extent

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S
E
W
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Ref. system Reference Systems

Reference system identifier
Reference system identifier
http://www.epsg-registry.org / EPSG:4326 / Inconnue
 

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Distribution Formats

Distribution format
Distribution format
  • CSV ( CSV)

 
Distributor
Distributor
 
Gouvernement du Canada; Environnement et Changement climatique Canada
 - Environment and Climate Change Canada (
Centre de renseignements à la population
)

200 Sacré-Coeur Blvd, Édifice Fontaine 12e étage
, Gatineau,
Québec
, K1A 0H3,
1-800-668-6767

http://ec.gc.ca
 
 

Overviews

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Keywords

Terres rares, lanthanum, neodymium, cerium, métaux, phytotoxicité
ECCC Information Category FR

Nature et biodiversité - contaminants
Fonctions de l'entreprise

Évaluer la toxicité de la présence dans l'environnement des substances et des déchets dangereux, les gérer et les surveiller
Évaluer la toxicité de la substance
Thésaurus des sujets de base du gouvernement du Canada

Toxicologie
local.theme.external.theme.EC_Branch

Direction générale des sciences et de la technologie
local.theme.external.theme.EC_Directorate

Sciences de la faune et du paysage
local.theme.external.theme.GC_Security_Level

Confidentiel


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