Emissions of ethene, propene, and 1‐butene by a midlatitude forest

A. H. Goldstein,S. M. Fan,S. C. Wofsy,J. W. Munger,M. L. Goulden

doi:10.1029/96jd00334

Abstract

Measurements of nonmethane hydrocarbon concentrations and gradients above Harvard Forest (42°32′ N, 72°11′ W) are reported for January through December 1993, along with inferred whole‐ecosystem emission rates for ethene, propene, and 1‐butene. Emissions were calculated using a micrometeorological technique where the ratio of observed CO2 fluxes and gradients were multiplied by the observed hydrocarbon gradients. Average emissions of ethene, propene, and 1‐butene during summer were 2.63, 1.13, and 0.41 × 1010 molecules cm−2 s−1, respectively. Emission of these olefins was correlated with incident solar radiation, implying a source associated with photosynthesis. In the northeastern United States, summertime biogenic emissions of propene and 1‐butene exceed anthropogenic emissions, and biogenic emissions of ethene contribute approximately 50% of anthropogenic sources. Our measurements suggest that terrestrial biogenic emissions of C2‐C4 olefins may be significant for atmospheric photochemistry.

Highlights

Ozone concentrations in the northeastern United States are believed to be sensitive to emission rates of biogenic nonmethanehydrocarbons(NMHC) [Fehsenfeldet al., 1992; McKeen et al, 1991; Rosell et al, 1991; Sillman et al, 1990]
Ethene,a plant Experiment hormone of interest to plant physiologists, has been Site studied in detail
74%of thetotalglobael missioonf ethene(35.4TgCyr-) Harvard Forestis locatedin Petersham,Massachusetts(42ø was from natural sources,89% from terrestrialecosystems 32' N, 72ø11' W; elevation 340 m), 100 km west of Boston, (78% from vegetationand 22% from soils), and 11% from Massachusetts and 100 km northeast of Hartford, aquaticecosystems.They estimatedaverageetheneemissions Connecticut

Summary

Introduction

Ozone concentrations in the northeastern United States are believed to be sensitive to emission rates of biogenic nonmethanehydrocarbons(NMHC) [Fehsenfeldet al., 1992; McKeen et al, 1991; Rosell et al, 1991; Sillman et al, 1990]. GOLDSTEIN ET AL.: ETHENE, PROPENE, AND 1-BUTENE EMISSIONS birch contributed2.0, 1.0, 0.5, and 0.5, respectively)in 1992, normallydownloadedat 6-day intervals. A 2-day sequenceof data for concentrationosf hexane,1butene, propene, and ethene (at 29 m), the raw gradient. The olefins, 1-butene, propene, and ethene, all have increased concentrationisn Julyrelativeto acetyleneowing to emission activeradiation(PAR) (measuredabovethe canopy)than the from the forest. Propene, and l-butene fifth run) (Figures5a-5d) revealsstrikingpatterns(corrected increasedlinearly with light, presentedas mean flux versus gradient is raw minus NULL). The correlation between gradients at night; correspondingdiurnal cycles were emissionsof olefins and incident light suggeststhat forest observed in the mean concentrations. CO2, especiallyduring stablemixing conditions,but not for Fluxes of ethene, propene, and l-butene during the the olefins. The relative fluxes estimated by butene than for propene or ethene. Our measurementsuggestthat terrestrialbiogenic emissionscould provide a significantglobal sourcefor two importantreactiveolefins,propeneand1-butene

References i

Findings

Conclusions