EFFECTS OF MEASUREMENT INTERVALS ON ESTIMATION OF AMMONIA EMISSIONS FROM LAYER HOUSES

Abstract

Continuous quantification of aerial emissions from animal feeding operations over an extended time period islabor and resource intensive. Strategically reducing measurement time to achieve comparable emission results is thus highlydesirable. This article delineates the effects of measurement intervals on estimation of annual mean and maximum dailyammonia emission rate (ER) of high-rise (HR) and manure-belt (MB) layer houses. The full dataset consisted of 318 dailyER values of four HR houses from weekly 48 h continuous measurement and 112 daily ER values of two MB houses frombi-weekly 48 h continuous measurements over one-year period. Each full dataset was sampled to yield subsets of daily ERat different intervals, i.e., one week (HR houses only), two weeks, one month, two months, or three months. The correspondingestimates of annual ammonia ER from the subsets were computed and compared with that of the full dataset. The resultsindicate that the annual mean daily ER values derived from the subsets progressively deviated from that of the full datasetby 3% to 37% for the HR houses and by 6% to 41% for the MB houses. The augmented measurement intervals (i.e., greaterthan bi-weekly for the HR houses and greater than monthly for the MB houses) led to considerable underestimation of thedaily maximum ER values, and thus are not recommended when daily maximum emission values are to be assessed.