Abstract
Hydrogen sulfide (H2S) from hog operations contributes to noxious odors in the surrounding environment and can be life-threatening. There is, however, limited understanding of what influences H2S emissions from these farms. Emissions of H2S were measured periodically over the course of two years at hog finisher farms in humid mesothermal (North Carolina, NC, USA) and semi-arid (Oklahoma, OK, USA) climates. Emissions were determined using an inverse dispersion backward Lagrangian stochastic model in conjunction with line-sampled H2S concentrations and measured turbulence. Daily emissions at the two lagoons were characterized by low emissions on most days with occasional days of high emissions. Mean annual area-specific emissions were much lower for the NC lagoon (1.32 µg H2S m−2 s−1 ± 0.07 µg H2S m−2 s−1) than the OK lagoon (6.88 µg H2S m−2 s−1 ± 0.13 µg H2S m−2 s−1). Mean annual hog-specific emissions for the NC lagoon were 0.75 g H2S hd−1 d−1 while those for the OK lagoon were 1.92 g H2S hd−1 d−1. Emissions tended to be higher during the afternoon, likely due to higher mean winds. Daily H2S emissions from both lagoons were greatest during the first half of the year and decreased as the year progressed and a reddish color (indicating high populations of purple sulfur bacteria (PSB)) appeared in the lagoon. The generally low emissions at the NC lagoon and higher emissions at the OK lagoon were likely a result of the influence of wind on mixing the lagoon and not the presence of PSB.
Highlights
Hydrogen sulfide (H2S) is a major source of odor and an asphyxiant
Emissions of H2S, calculated over half-hour averaging periods, were determined by single value decomposition of the matrix composed of a flux versus concentration relationship for each of the synthetic open-path systems (S-OPS) around the lagoon obtained using a backward Lagrangian stochastic model (WindTrax; Thunder Beach Scientific, http://www.thunderbeachscientific.com, accessed on 19 December 2019), using the turbulence statistics derived from the on-site sonic anemometer measurements
Half-hour averaging periods were excluded from analysis when one or more of the following was true: (1) the absolute value of the Monin Obukov length (L) was less than 2 m [20,21], (2) the friction velocity was less than 0.15 m s−1 [21,22], (3) less than 5% of the backward trajectory parcels originated within the lagoon source area, (4) the wind direction standard deviation was greater than 30◦, (5) the mean wind direction was greater than 60◦ off the S-OPS perpendicular, or (6) the calculated Cbg was greater than the instrument minimum detection limit (MDL)
Summary
Hydrogen sulfide (H2S) is a major source of odor and an asphyxiant. emissions of H2S are monitored nationally through the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) and the Emergency Planning and Community Right-to-Know Act (EPCRA). Many anaerobic treatment lagoons have periods in which they appear reddish-purple [5] This coloring is usually a result of the presence of large populations of purple sulfur bacteria (PSB) from the family Chromatiaceae in the phototrophic regions of the lagoon. These bacteria can photosynthesize anoxygenically and oxidize H2S rising from the lower reaches of the lagoon to SO42− [5,6], reducing emissions from the lagoon surface [7,8]. Purple non-sulfur bacteria (PNSB) have been found in swine lagoons but are unable to oxidize zero-valent sulfur to sulfate and have a competitive disadvantage in a HS--rich anaerobic lagoon [5]. LLaaggoooonn aanndd mmeeaassuurreemmeenntt ccoonnffiigguurraattiioonnss..TThheemmeaesausruermemenetnctocnofnigfiugruartaiotinosnastatthtehNe CNClalaggoooonn(a(a))aannddOOKKllaaggoooonn((bb))..SSoolliiddwwhhiitteelliinneessiinnddiiccaattee llooccaattiioonnss ooff SS--OOPPSS wwhhiillee wwhhiittee cciirrcclleessaanndd‘‘xx’’ ininddicicaateteththeeloloccaatitoionnssoof fththeemmeeteteoororolologgiciacal lananddlalgagoooonnmmeaesausurermemenentstsrersepspecetcitvievleyl.y
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