Foliar uptake of peroxyacetyl nitrate (PAN) by herbaceous species varying in susceptibility to this pollutant

Abstract

SUM M A R YFoliar uptake of peroxyacetyl nitrate (PAN) was measured by the gas exchange method on nine herbaceous species. Susceptibility to PAN was also examined in the tested species in order to seek correlations with the uptake rate of PAN. PAN was synthesized by the nitration of peracetic acid in /;-tridecane.Uptake rate of PAN by the leaves was kept at a steady level during the 90 min light period, w-hile in the dark it declined rapidly and reached almost zero within 30-^5 min. This suggests that adsorption of PxiXN on to the surface of the leaves is very small and most of it enters the leaf through open stomata.Among the species tested, sunflower showed the highest rate of PAN uptake, followed by radish, tomato and spinach. Maize and soyahean exhibited the lowest rate. .\ highly significant correlation was observed between the rate of PAN uptake and stomatal conductance among the tested species.Petunia was most susceptible to PAN, followed by radish and tobacco, but maize and peanut were tolerant. There was no significant correlation between the uptake rate of PAN and susceptibility to it among the species. A higher susceptibility of petunia to PAN was not characterized by a higher rate of pollutant uptake. These results show that the main factor determining the differences between species in susceptibility to PAN is not the amount that gains access to the tissues, but some internal metabolic processes.

Twin-cuvette measurement technique for investigation of dry deposition of O<sub>3</sub> and PAN to plant leaves under controlled humidity conditions

“…The linear relationship between the measured and calculated stomatal conductance to O 3 (R pearson = 0.99; CI 95 % = 0.07) and PAN (R pearson = 0.91; CI 95 % = 0.1) shows predominantly stomatal uptake of both gas species, which agrees with results of previous studies (Okano et al, 1990;Sparks et al, 2003;Doskey et al, 2004;Fares et al, 2008Fares et al, , 2010. For the calculation of g s,meas we assumed that vmr int,leaf (O 3 ) was close to zero (Laisk et al, 1989;Doskey et al, 2004) as well as for PAN (see Sect.…”

“…Both Okano et al (1990) and Teklemariam and Sparks (2004) used relatively high PAN mixing ratios (up to 190 ppb) for fumigation, which do not correspond to the PAN mixing ratios found under typical environmental conditions. Furthermore, the obtained deposition velocities in these studies differed considerably (see Table 1), which might be attributed to the use of different plant species and measurement methods.…”

Eddy covariance fluxes of acyl peroxy nitrates (PAN, PPN and MPAN) above a Ponderosa pine forest

“…Studies on herbaceous species (e.g. crops) show higher rates of PAN deposition, but the range (0 to −0.7 cm s −1 ) is more variable across species (Hill, 1971;Okano et al, 1990;Schrimpf et al, 1996;Sparks et al, 2003). PAN transfer to deciduous and coniferous forests is typically the most efficient, with V ex <−0.5 cm s −1 , in agreement with our results (Shepson et al, 1992;Sparks et al, 2003;Turnipseed et al, 2006;Farmer and Cohen, 2008).…”

“…PAN transfer to deciduous and coniferous forests is typically the most efficient, with V ex <−0.5 cm s −1 , in agreement with our results (Shepson et al, 1992;Sparks et al, 2003;Turnipseed et al, 2006;Farmer and Cohen, 2008). Laboratory studies have demonstrated a strong dependence of PAN uptake on light that alludes to the role of stomatal transport (Okano et al, 1990;Sparks et al, 2003). Observations of non-zero uptake at night, however, imply deposition also occurring on other surfaces, such as leaf cuticles, tree boles, soil or ground litter (Shepson et al, 1992;Schrimpf et al, 1996;McFadyen and Cape, 1999;Turnipseed et al, 2006).…”

“…Advances in instrumentation have since permitted the use of more direct measurement techniques, such as eddy covariance (EC); however, results are far from conclusive. A recent 12-day set of speciated APN EC flux measurements demonstrates downward fluxes over a Loblolly pine plantation (Turnipseed et al, 2006) with magnitudes similar to prior studies and consistent with leaf-level uptake experiments (Okano et al, 1990;Sparks et al, 2003). In contrast, Farmer and Cohen (2008) report a noon summertime upward flux (efflux) velocity of +0.7 cm s −1 for total peroxy nitrates over a Ponderosa pine forest, which they attribute to withincanopy photochemical production that occurs faster than depositional loss.…”