Seasonal emissions of isoprene and other reactive hydrocarbon gases from the ocean

Abstract

Abstract. In this paper we show evidence that isoprene emission from the oceans is strongly seasonally dependent and is correlated with the chlorophyll content of the water from measurements in the North Sea and Southern Ocean. We estimate the seasonally averaged flux of isoprene to the atmosphere to be 1.7 x 107 molecules cm '2 s '•, which may be significant for atmospheric chemistry in locations remote from land as it is the only known source of atmospheric isoprene in these regions. We observe a strong seasonal cycle of several other NMHCs in seawater at high latitudes, with a maximum in summer. This will distort current estimates of the annual marine flux of NMHCs to the atmosphere which may need to be reduced by up to an order of magnitude to account for lower emissions in winter.

Time-resolved variations in the distributions of inorganic ions, carbonaceous components, dicarboxylic acids and related compounds in atmospheric aerosols from Sapporo, northern Japan during summertime

“…Similarly, the air masses originated from the western North Pacific (region #3) may be enriched with non-methane hydrocarbons (NMHCs) because of larger emission of NMHCs from phytoplankton in summer, in which alkenes such as ethene, propene, butene and isoprene are predominant (Broadgate et al, 1997;Matsunaga et al, 2002). In addition, the contribution of isoprene from higher plants should have also been significant as the air masses passed over Okinawa Island, Japan where isoprene emissions from the plants are significant (Tambunan et al, 2006).…”

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

“…Oceanic concentrations of DMS are a monthly climatology from Lana et al (2011). Isoprene concentrations in the ocean are calculated using the parameterization of Broadgate et al (1997), relating isoprene and chlorophyll concentrations, here with chlorophyll prescribed as a monthly climatology from the World Ocean Atlas 2001 . For methanol, the atmosphere-toocean flux is calculated assuming a constant undersaturation of surface water methanol with respect to lowermost atmospheric concentrations (Singh et al, 2003).…”

Marine Organic Halide and Isoprene Emissions Near Mace Head, Ireland

“…[12] Isoprene is emitted directly by phytoplankton and may be indirectly produced by zooplankton grazing. [11] Monoterpenes, including α-pinene, β-pinene, camphene and limonene, as well as more minor contributions from other terpenes, are also measured 292 in all air samples, but the vertical gradient indicates that they likely have a different source from the alkyl halides.…”

“…It is possible that the warmer water during this experimental period (September) may have stimulated increased emissions, since productivity and emissions generally increase with environmental temperatures. [11] Seaweed (macroalgae) present in the Mace Head area has been identified as a source for several alkyl halides: CH 2 Br 2 , CHBr 3 , and CH 2 I 2 . [3] CH 2 I 2 , CHBr 3 , and CH 2 ICl concentrations are reported to increase at low tide, when more of the macroalgae are exposed to air.…”