Diurnal and seasonal variations of odor and gas emissions from a naturally ventilated free-stall dairy barn on the Canadian prairies

Figures & data

Figure 1. Inside view and brief schematic plan of the dairy barn.

Figure 2. 3-Hour average VR, OC, and OE in the cold (a), warm (b), and mild (c) seasons (error bar was plotted by standard deviation).

Figure 3. 3-Hour average NH₃ C and NH₃ E in the cold (a), warm (b), and mild (c) season.

Figure 4. 3-Hour average H₂S C and H₂S E in the cold (a), warm (b), and mild (c) seasons.

Table 1. Descriptive statistics of 3-hour average odor, NH₃, and H₂S concentrations and emissions in the cold, warm, and mild seasons.

	Cold			Warm			Mild
Items	Minimum	Maximum	Mean (SD)	Minimum	Maximum	Mean (SD)	Minimum	Maximum	Mean (SD)
VR (m^3 sec^−1)	5.0	8.5	6.7 (1.1)^b	19.1	33.5	27.9 (5.3)^a	24.2	135.5	60.3 (45.8)^a
OC (OU m^−3)	381	897	630 (153)^a	153	549	370 (125)^b	311	483	403 (64)^b
OE (OU sec^−1 AU^−1)	11.7	35.0	24.3 (6.9)^b	32.5	109	66.2 (25.7)^ab	60.5	279.2	130.1 (86)^a
OE (OU sec^−1 m^−2)	0.6	1.9	1.3 (0.4)	1.6	5.2	3.2 (1.2)	3.2	14.8	6.9 (4.5)
OE (OU sec^−1 cow^−1)	17.6	52.8	36.7 (10.5)	49	165	100 (38.8)	91.4	421.5	196.5 (130)
NH3 C (ppm)	16	31	23 (6)^a	2	8	5 (2)^b	1	6	4 (2)^b
NH3 E (mg sec^−1 AU^−1)	0.4	0.9	0.6 (0.2)^a	0.3	0.8	0.6 (0.2)^a	0.5	0.9	0.6 (0.1)^a
NH3 E (μg sec^−1 m^−2)	21.7	48.3	35.1 (8.2)	12.6	38.9	27.9 (7.7)	24.1	47.8	33.1 (7.6)
NH3 E (mg sec^−1 cow^−1)	0.60	1.34	0.98 (0.23)	0.40	1.23	0.88 (0.25)	0.69	1.37	0.95 (0.22)
H2S C (ppb)	186	275	217 (42)^a	211	193	176 (29)^b	0	28	13 (9)^c
H2S E (μg sec^−1 AU^−1)	9.4	15.1	12.2 (2.4)^b	35.2	68.3	48.2 (11.4)^a	0.1	7	3.5 (2.1)^b
H2S E (μg sec^−1 m^−2)	0.5	0.8	0.7 (0.1)	1.7	3.3	2.3 (0.5)	0.01	0.4	0.2 (0.1)
H2S E (μg sec^−1 cow^−1)	14.2	22.9	18.5 (3.6)	53.2	103	72.8 (17.3)	0.2	10.6	5.3 (3.2)

Note. C is concentration and E is emission; SD is standard deviation. The letters a, b, and c are used to indicate the significance of the difference in the measured items among the three seasons at the 0.05 level; the same letters show the difference is not significant. The minimum, maximum, and mean were calculated from the 3-hr diurnal averages of the two days in each season.

Figure 5. Seasonal VR and concentrations and emissions of odor, NH₃, and H₂S.

Table 2. Descriptive statistics of seasonal odor, NH₃, and H₂S concentrations and emissions.

Items	Minimum	Maximum	Mean ± SD
OC (OU m^−3)	203	639	437 ± 134
OE (OU sec^−1 AU^−1)	17.2	84.4	45.9 ± 24.2
OE (OU sec^−1 cow^−1)	26	127.5	69.3 ± 36.6
OE (OU sec^−1 m^−2)	0.89	4.22	2.38 ± 1.24
NH3 C (ppm)	2	29	9 ± 7.3
NH3 E (mg sec^−1 AU^−1)	0.27	0.92	0.53 ± 0.18
NH3 E (mg sec^−1 cow^−1)	0.41	1.39	0.80 ± 0.27
NH3 E (μg sec^−1 m^−2)	14	50	28 ± 10
H2S C (ppm)	0.01	0.20	0.13 ± 0.06
H2S E (μg sec^−1 AU^−1)	3	105	28 ± 32
H2S E (μg sec^−1 cow^−1)	4.7	157.8	41.5 ± 48.2
H2S E (μg sec^−1 m^−2)	0.16	5.23	1.42 ± 1.63

Note. C, E, and SD are described in Table 1. The minimum, maximum, and mean were calculated from the 12 daily averages for the 12 months.

Table 3. Indicator (the ratio of 8-hr average concentration to T-TLV) of individual gas concentration levels and their combined indicator.

	Cold		Warm		Mild
	February 9	February 12	July 21	July 23	October 13	October 15
NH3 C	1.09	0.68	0.16	0.21	0.11	0.11
H2S C	0.22	0.16	0.18	0.21	0.01	0.01
Combined	1.31	0.84	0.34	0.42	0.12	0.12

Note. T-TLV is time-weighted average (8-hr) threshold limit value and C is concentration.

Figure 6. Comparison of modeled results and observed results: (a) comparison of OE_m and OE_o using 70% of the data, and (b) validation using the remaining 30% of the data.