Trimethylamine emissions in animal husbandry

Abstract

Abstract. Degradation of plant material by animals is an important transformation pathway in the nitrogen (N) cycle. During the involved processes, volatile reduced alkaline nitrogen compounds, mainly ammonia (NH3) and aliphatic amines such as trimethylamine (TMA), are formed. Today, animal husbandry is estimated to constitute a main source of aliphatic amines in the atmosphere with TMA being the main emitted compound. Here, we show how the interaction between faeces and urine in animal production systems provides the primary source for agricultural TMA emissions. Excreted urine contains large quantities of urea and TMA-N-oxide, which are transformed into NH3 and TMA, respectively, via enzymatic processes provided by microbes present in faeces. TMA emissions from areas polluted with urine–faeces mixtures are on average of the order of 10 to 50 nmol m−2s−1. Released amines promote secondary aerosol particle formation in the agricultural emission plume. The atmospheric lifetime of TMA, which was estimated to be of the order of 30 to 1000 s, is determined by the condensation onto aerosol particles.

Ideas and perspectives: on the emission of amines from terrestrial vegetation in the context of new atmospheric particle formation

“…Comparing their results to existing concentration measurements, they suggest, however, that emissions further away from urban areas, and hence concentrations, might be substantially underestimated. This would be emphasized even more strongly by the finding that the estimated agricultural amine emissions do not scale with a constant ratio throughout all NH 3 emission stages Sintermann et al, 2014). In conclusion, the short atmospheric residence time of MAs implies that only local to regional emissions are crucial in promoting NPF.…”

“…Further on, we focus on MA as a surrogate for other airborne amines. The most important identified MA sources (Ge et al, 2011a) are agriculture (Schade and Crutzen, 1995;Kuhn et al, 2011;Sintermann et al, 2014), biomass burning (Lobert et al, 1990;Andreae and Merlet, 2001), and the ocean (van Neste et al, 1987;Gorzelska and Galloway, 1990;Wang and Lee, 1994;Gibb et al, 1999b;Facchini et al, 2008). Many marine algae produce MAs (Steiner and Hartmann, 1968;Smith, 1971Smith, , 1975, and even remote ocean water contains MA (and the TMA-precursor trimethylamine-N-oxide) (Gibb et al, 1999b, a;Gibb and Hatton, 2004).…”

“…Hence, the emissions of the alkaline gases determine, to a large extent, the potential for NPF. In polluted air masses, for example close to intensive agricultural activities or in urban environments, usually enough airborne NH 3 and MAs exist (Ge et al, 2011a;Sintermann et al, 2014) to favour high NPF rates. The high concentrations of existing particles often hinder NPF by acting as a coagulation sink for newly formed clusters (Kerminen et al, 2001;Dal Maso et al, 2007;Westervelt et al, 2014).…”

“…The latter is an efficient removal process yielding a range of MA lifetimes depending on the aerosol number-size distribution and the assumed uptake coefficient (defined as the fraction of molecules being permanently removed from the gas phase by collision with an existing particle). Sintermann et al (2014) roughly estimate a condensation sink lifetime of TMA of 0.5 and 17 min for a high and lower aerosol burden, respectively, based on an uptake coefficient of 1. Using a chemistry-transport model, approximating amine emissions by scaling with those of NH 3 (the approach taken by Schade and Crutzen, 1995), including oxidation, deposition, and the condensation sink; Yu and Luo (2014) derive atmospheric MA lifetimes.…”

“…On the other hand, traces of TMA + PA and a C4-amine (unquantified) were detected (Sipilä et al, 2015). Schade and Crutzen (1995) estimated an average MA : NH 3 emission ratio of 0.7 % from agricultural sources, which are assumed to dominate the anthropogenic MA source; likewise, Sintermann et al (2014) measured a maximum TMA emission ratio of 1 %. By contrast, simultaneous measurements of MAs and NH 3 at a coastal-rural site, with potential marine source influence, indicated timeaveraged concentration ratios DMA : NH 3 = 1.6 to 3.5 % and TMA : NH 3 = 0.75 to 3.9 % (Freshour et al, 2014).…”