Characterization of Indoor Atmospheric Nitrogenous Chemicals in Poultry Farms

Guo X, Afroz R, Wu S, Wong K, Carney V, Zuidhof M, et al. Characterization of Indoor Atmospheric Nitrogenous Chemicals in Poultry Farms. ChemRxiv. 2024; doi:10.26434/chemrxiv-2024-sjl0x

About

The poultry industry faces a challenging air pollution problem in indoor poultry facilities. Elevated levels of air pollutants are found in the farm, including carbon dioxide, ammonia (NH3), particulates (PM10, PM2.5), and VOCs. Concentrations of these pollutants have been a concern to the productivity and welfare of chickens. The major source of air pollutants in a poultry farm comes from chicken manure. Understanding chemical processes occurring in indoor poultry facilities plays a crucial role in managing ongoing NH3 pollution, as well as mitigating risks associated with farmers’ health and animal welfare. The objective of this study is to project novel insights into nitrogen cycles in indoor poultry farms. This study will demonstrate a new method for time-resolved collection and quantitation of ANCs. Secondly, the distribution of ANCs in different phases (air, particles, and litter) will also be evaluated. Thirdly, using the UA as an example, the correlation between ANCs and IAQ parameters will be addressed using aerosol monitoring instruments. We aim to provide a comprehensive evaluation of airborne nitrogenous chemicals (ANCs), which can play a key role in terms of air quality, occupational health, agricultural productivity, and animal welfare in livestock facilities.

Approach

Instrumentation Aerosol samples were collected by a particle-into-liquid sampler (PILS) (Model 4001), and an auto collector manufactured by Brechtel Inc. Functionality tests of all instruments were carried out preliminary in the Poultry Research Center (PRC) at the University of Alberta. The farm had floor pen housings for a small flock of 70 birds. Commercial farm samples involved in this study were collected on a farm located near Camrose, Alberta, Canada. The farm was a completely indoor, free-run, organic table egg farm. The barn we sampled was home to 8000 birds at approximately 60 to 70 weeks of age. In the commercial farm, on-site instrument testing and trial sample collection were performed between November 2022 and March 2023. Collected field samples were analyzed on the same day in the lab. Chicken litter samples were collected by hand-picking chicken litter from five random locations inside the farm. During this experiment, we measured a stable source of ammonia and ammonium bisulfate particles in replicates.

Analysis of Results

We observed that the presence of ANCs is different among the three phases, with the litter phase having the greatest variety of compounds, while not all ANCs are present in the gas or particle phase. Four ANCs are detected in the particle sample, suggesting that these compounds are major forms of nitrogenous compounds in suspended dust and can be exposed to producers and chickens via inhalation. The indoor environment of a commercial poultry farm is very dynamic, and the concentration of pollutants is often governed by the activity of chickens, ventilation, and farm infrastructures. Hence it is very challenging to find a representative concentration even for the most commonly measured air pollutants (i.e., NH3 and PM). Most particles in the farm atmosphere were greater than 0.25 µm. TPM varied according to the local activities of chickens. Our study indicated that 1) TPM is a major carrier of airborne UA– which agrees with discussions in previous sections, and 2) The fluctuating concentration of airborne UA reflects the changing chicken activities on the farm. This agreement also confirms that UA shares a relatively stable ratio in airborne particles, which again implies that airborne UA has a consistent source, e.g., the suspension of manures.

Application

Overall, our study has provided new insights into air pollutants that can be associated with the formation of NH3 gas. Elevated concentrations of ANCs can directly reduce indoor air quality. Hence putting the producers’ occupational health at risk. More importantly, birds’ welfare, productivity, and the cost-effectiveness of investments made to farm ventilation will also diminish. ANCs are key components in the nitrogen cycle in poultry farms, at the same time, serving as the precursors of ammonia. Events that are causing acute rises in airborne ANCs can also put farmers’ health at risk when proper personal protection equipment is absent. Overall, our study has provided new insights into air pollutants that can be associated with the formation of NH3 gas. According to discoveries made by this work, resolving indoor air pollution in poultry housings may benefit from taking a different approach. First, controlling NH3 formation in poultry facilities requires a better picture of the entire nitrogen cycle. As demonstrated in this work, many ANCs are involved in the nitrogen pool, likely making a variable degree of contribution to NH3 production. Thus, the removal of ANC precursors in the environment would be beneficial, and future studies should explore technologies that can make this possible.

Abstract

Indoor air pollution is seen in poultry and many other animal husbandry industries. Small airborne nitrogenous chemicals (ANCs), such as ammonia and small amines, are common air pollutants in poultry farms. Elevated ANC concentration in poultry farms can significantly worsen the indoor air quality (IAQ) of the farm, which will affect animal productivity, animal welfare, and occupational health of producers. Re- cent studies have identified ammonia and small volatile organic pollutants in the farm. On the other hand, characterization of large ANCs, such as uric acid (UA) and large amines have rarely been reported, despite they are proposed as the major source of biological nitrogen waste. Our goal is to project a novel insight into nitrogen cycles in poultry farms. This project includes on-site time-resolved collections of ANCs using a particle-into-liquid-sampler (PILS), followed by chemical characterization by liquid chromatography-mass spectrometry (LC-MS) with a novel derivatization method. Over quantitative assessment of ANCs in the poultry farm, we discovered UA and suspended particles are correlated with changing animal behaviors. Phase partition- ing of UA, ammoniacal species, and large amines were discovered among air, particle, and litter materials. The discovery of these indoor pollutants can be associated with the formation of dust particles and ammonia, and the results can benefit the poultry industry in solving persisting IAQ problems.KEYWORDS: Indoor Air Quality, Poultry, Occupational Health, Animal Welfare, Ammonia, Uric Acid, Amines, LC-MS, Tosyl Chloride