2.27 - Fluoride in Vegetation

Results for the years 2007-2010 will be published when results for 2010 are ready for publication in April 2011.

Rationale for Indicator Selection

Fluoride can adversely affect the growth and vitality of vegetation. Fluoride emitted from the Fjardaal smelter could accumulate in vegetation in the immediate vicinity of the smelter.

Communities in East Iceland are concerned about the changes in their ecosystem if fluoride emissions exceed the tolerance threshold of local plants.

Fluoride can directly impact vegetation and could cause the localized extirpation of sensitive floral species. Fluoride accumulation is also hazardous to grazing mammals.

Vegetation could accumulate fluorides in concentrations that are hazardous to herbivorous mammals, and this in turn could influence humans if they eat those mammals.

Metric

1. Concentration of F in vegetation (ruminant forage) at designated sample plots within a specified radius of the smelter (Project effect: direct).

Target

1. Coniferous leaves, broadleaves, and vegetables : >0.4 µg/m³
   Grasses: >3 µg/m³
   Lichens & Mosses: >0.3 µg/m³
   Source: AW Davidson and L. Weinstein; EIA, 2001

Monitoring Protocol

1. Samples collected from designated stations during the growing season:
   - 40 samples of coniferous leaves, broadleaves, vegetables and vegetable leaves collected in Reydarfjordur (ten samples for each vegetation type) and analyzed for F, N, S and heavy metals
   - 30 samples of forage grass collected in Reydarfjordur and analyzed for F and S/N ratio
   - Mosses, lichens, and broadleaf plant collected from 30 stations and analyzed for F
   - Lichen on rock photographed at 50 locations in Reydarfjordur.
   - Ecological survey: Vegetative species composition and vegetation cover (%) recorded in 150 vegetation quadrats in 30 sample stations around Reydarfjordur. Quadrats photographed.
    
   Vegetation in Reyðarfjörður visually inspected for fluoride impact
    

Baseline

i. The background fluoride content of vegetation varies with the soil, species, type of leaf, age and the presence of natural sources of fluoride such as dust so it is not possible to state precise background concentrations of fluoride. However, the scientific literature shows that most samples are <5 μg F/ g (dry wt), a proportion may have up to 10 and some may have as high as 20 or so μg F/ g. Fruit, stalks and roots have much lower fluoride contents than leaves.

Interpretation

Most analyses fell within the expected range for background samples. Higher than expected fluoride concentrations were found in one sample of Sorbus most rhubarb leaves (but not the edible stalks) and some moss samples. The one sample of strawberry fruit had a slightly high fluoride content and so did some potato leaves. These were investigated in 2004 and 2005 and it was concluded that:

1. The slightly high fluoride in the strawberry fruit and potato leaves was probably due to dust / soil contamination. Washing fruit usually removes this material.

2. The one high rowan sample was due to contamination from burning waste in a nearby fire.

3. The high fluoride concentrations in rhubarb leaves were due to the fact that it is one of a small number of species that can accumulate fluoride from the soil. This was not previously known. Note that the edible stalks had low fluoride contents.

4. The elevated fluoride in the moss samples correlated with the presence of sources of dust from construction and roads (all dust and soil debris contains measurable amounts of fluoride).

Additional Resources

Fluoride in vegatation. Baseline Report