Nitrogen Deposition Flashcards
Where are wet and dry deposition of nitrogens found?
Wet deposition = in rain
Dry deposition = as gas or aerosols
What are the reduced and oxidised forms of nitrogen in wet and dry depositions?
Wet:
Oxidised = NO3- (nitrate)
Reduced = NH4+ (ammonium)
Dry:
Oxidised = N2O (nitrous oxide)
Reduced = NH3 (ammonia)
What are the main anthropogenic sources of oxidised and reduced nitrogen?
Oxidised (NOx) = fossil fuel combustion
Reduced (NHy) = Agriculture (especially ammonia from manure)
What factors affect nitrogen deposition?
Distance from source:
less important for NOx but important for NHy
Surface roughness:
deposition velocities faster to rougher surfaces
Rainfall:
greater rainfall increases wet deposition
Seeder-Feeder effect
What is the Seeder-Feeder effect?
Seeder cloud has wet deposition of nitrogen
Feeder cloud attached to a mountain
Feeder cloud takes up and traps pollutant from the seeder cloud
Air pollutants are rained on the mountain from the feeder but also get double dose of pollutants due to the ones passed from the seeder cloud
Where are the highest rates of nitrogen deposition in the UK?
Some upland areas due to seeder-feeder effect
Areas near major industrial centres and agriculture
Forests (due to high surface roughness)
Peak District and the pennines
What are the four mechanisms of nitrogen deposition as ecological threat?
Eutrophication:
Nitrogen accumulation in soil allows expansion of nitrophilous species
Can result in competitive exclusion of others and decline in biodiversity
Soil acidification:
can reduce plant health and productivity
can after community composition and cause a decline in species richness
Increased susceptibility of plants to secondary stress:
greater herbivory, reduced resistance to pathogen attack and increased susceptibility to drought and/or freezing damage
Direct toxicity to plants
