AgriMultiPOL : Assessment of pollutant emissions by a typical farm

Context

Agriculture is an important source of atmospheric emissions. Many studies already yielded an assessment of its emissions of greenhouse gases or ammoniac (93% of emissions attributed to agriculture), and reduction practices. On the other hand, knowledge about other pollutants such as particles and their precursors, in particular volatile organic compounds (COV), remains patchy. CITEPA French emission inventories estimate that agriculture contributes about 40% to COV anthropogenic emissions, and about 7% and 25% to PM_2.5 et PM₁₀ particulate emissions, respectively, but with large uncertainties. According to the scientific litterature, agricultural emissions would even be a predominant source of fine particles in Europe.

Objectives and strategy

The project AgriMultiPol aimed to identify key pollutants (COV, pesticides, ammoniac and particles) and assess their emissions from different activities in a typical multi-activity farm. Measurements have been performed with well established recent techniques, within the AgroParisTech experimental farm at Grignon (Yvelines), which combines cereal crops and livestock (cattle, sheep) in a peri-urban environment 30 km west of Paris.

Two types of experimentations have been conducted:

• Characterisation of compounds at the emission (barn, sheepfold and farm exterior);
• Monitoring of atmospheric concentrations downwind of the farm (ICOS FR-Gri station), and apportionment of the various agricultural sources.

Moreover, emissions of some compounds have been estimated using inverse modelling, and the eddy covariance method over some periods.

Results

Exhaustive chemical fingerprinting of VOCs in livestock buildings has enabled us to detect, identify and quantify over 400 compounds. about half are oxygenated VOCs, a third, hydrocarbons, and the rest is composed of nitrogen, sulphur and some halogen compounds. Although relatively similar, chemical fingerprints of the stable and sheepfold show some specificities : triazine is only detected in the stable, when pyridine and its derivatives are only detected in the sheepfold. These compounds could be used as tracers of the respective breeding buildings. In addition, concurrent CO₂ measurements allowed us to derive VOC emission factors of these sources. Extrapolated at the national scale, their emissions would be of the same order as those from the road traffic.

A particularly significant achievement is the on-line monitoring of a fungicide during three weeks over a treated plot, using a PTR-MS instrument.  It was the first deployment of this analyser in field conditions, and the longest observation period of the volatilization of a pesticide under ambient conditions.

Other results of AgriMultiPol:

• the agricultural source contributes to about 20% of ambient VOC concentrations;
• the agricultural source contributes to fine particles (in particulier to nitrate) but at the regional scale (comparison to another peri-urban site in Ile-de-France);
• particle nucleation episodes occur during both day and night; night-time events had rarely been observed before and seem related to regional agricultural emissions;
• herbicide and slurry inputs yield significant emissions of some VOCs.

Finally, the relation between the ¹³C signature of methane and the C3-C4 animal feed known for cattle appears valid for sheep. This constant fractionation might allow a better assessment of methane emissions by ruminant livestock.

More

• Article (in French) Agriculture et qualité de l’air (La Météorologie, 2019)
• Article on VOC emissions in livestock buildings (Science of the Total Environment, 2020)
• Article on the formation of new particles on a peri-urban agricultural site (Science of the Total Environment, 2023)

Coordination and partnership

Laboratoire des Sciences du Climat et de l’Environnement – UMR 8212 (CNRS-LSCE)
Laboratoire d’Écologie Fonctionnelle et Ecotoxicologie des Agroécosystèmes – UMR 1402 (INRAE-ECOSYS)

Coordination contact: Valérie Gros

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