NOx :: Mosses and liverworts (general)

Latin name: 
Bryophytes (general)

Impact Type: Direct exposure to pollutant

Key Concerns:

Studies in relation to nitrogen oxide pollution gradients are limited and the is a need for further research (Mulgrew & Williams 2000). Morgan et al. (1992) have shown that exposure to NOX can affect the assimilation of wet deposited nitrogen in a range of bryophyte species (Ctenidium molluscum, Homalothecium sericeum, Pleurozium schreberi and Hylocomium splendens). However, these plants can recover their normal nitrogen metabolism after a pollution-free period. In the long term it is unlikely that NOX will be a major cause of toxicity problems at typical rural concentrations, but deposition of NOX will add to overall nitrogen loading (Lee et al. 1993). The accumulation of the isotope 15N in mosses close to roads has been suggested as an indicator of NOX exposure (Pearson et al., 2000).

Additional Comments:

One of the few studies which has been carried showed that the distribution of epiphytic bryophytes was less where NO2 levels were > 0.02 ppm (Inui and Yamaguchi, 1996). 

Critical Load/level: 
Critical Load/ Level

No estimate available

References: 
Lee, J.A.; Parsons, A.N.; Baxter, R. 1993 Sphagnum species and polluted environments, past and future Advances in Bryology 5 297-313
Morgan, S.M.; Lee, J.A.; Ashenden, T.W. 1992 Effects of Nitrogen-Oxides on Nitrate Assimilation in Bryophytes New Phytologist 120 89-97
Mulgrew, A.; Williams, P. 2000 Biomonitoring of air quality using plants. Air Hygiene Report No 10
Pearson, J.; Wells, D.M.; Seller, K.J.; Bennett, A.; Soares, A.; Woodall, J.; Ingrouille, M.J. 2000 Traffic exposure increases natural 15N and heavy metal concentrations in mosses New Phytologist 147 317-326

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