Harvesting equipment to reduce particulate matter emissions from almond harvest

Figures & data

Figure 1. Layout of sampled orchard (not to scale; adapted from Faulkner et al., 2011).

Figure 2. Sampler configuration (not to scale). Tree rows ran perpendicular to the “S1–S4” sampler array.

Figure 3. Scanning electron microscope image of collected PM particles.

Table 1. Fractionation categories

Particle size
Minimum	Maximum	Category
16 mm	—	Nuts and twigs
9.5 mm	16 mm	Leaves, small nuts, and twigs
8 mm	9.5 mm	Leaves and grass
1 mm	8 mm	Grass
—	1 mm	Soil

Table 2. Meteorological parameters measured onsite during sampling (Exact harvester)

	Exact harvester			Conventional harvester
	Minimum	Maximum	Average	Minimum	Maximum	Average
Albedo	0.21	0.35	0.23	0.20	0.24	0.22
Relative humidity (%)	20	55	33	21	47	31
Temperature (°C)	24	30	27	24	31	27
Solar radiation (W/m^2)	5	843	512	54	1,008	550
Wind speed (m/sec)	0.5	2.6	1.7	0.5	2.7	1.5

Table 3. Particle size distribution parameters from TSP filters (Exact harvester)

	Exact harvester	Conventional harvester
MMD (µm AED)^[	15.3 x	16.2 x
GSD	2.11 x	2.20 x
Average % PM10	30.6	29.1
Average % PM2.5	0.8	1.0
Note: No statistical differences were detected in means in the same row followed by the same letter (α = 0.05). MMD = mass median diameter. AED = aerodynamic equivalent diameter. GSD = geometric standard deviation. Average % PM10 obtained utilizing eq 2 with d50 = 10 µm and FEC slope = 1.5.

Table 4. Emissions (kg/km²) from harvest treatments (Exact harvester; n = 8 per treatment)

	TSP	True PM10	True PM2.5	FRM PM10	FRM PM2.5
Emissions
Exact E4000	1,149	369	12	561	264
Conventional	4,835	1,300	39	1,981	401
Reduction	76%*	72%*	69%*	72%*	34%
Significance
Within-subject	0.373	0.524	0.275	0.930	0.840
Between-subject	0.002	0.013	0.006	0.002	0.931
Note: Reductions marked with asterisks were significant at p = 0.10.

Table 5. Size separation results (Exact harvester)

	Mass fraction (%)
Size separation range	Exact harvester	Conventional harvester
Nuts and twigs	75.7 (2.6) x	72.2 (2.6) x
Leaves, small nuts, and twigs	19.6 (2.0) x	20.5 (2.0) x
Leaves and grass	0.8 (0.1) x	1.1 (0.1) x
Grass	1.5 (0.4) x	2.5 (0.4) x
Soil	2.4 (0.4) x	3.7 (0.4) y
Note: No significant differences were detected in means in the same row followed by the same letter (α = 0.05). Standard errors are shown in parentheses.

Table 6. Meteorological parameters measured onsite during sampling (Flory harvester)

	Flory 8550 harvester			Conventional harvester
	Minimum	Maximum	Average	Minimum	Maximum	Average
Albedo	0.23	0.30	0.25	0.21	0.27	0.24
Relative humidity (%)	13	24	18	13	23	18
Temperature (°C)	32	35	34	30	35	34
Solar radiation (W/m^2)	331	846	681	469	826	678
Wind speed (m/sec)	1.1	2.3	1.7	0.6	2.0	1.4

Table 7. Particle size distribution parameters from TSP filters (Flory harvester)

	Flory 8550 harvester	Conventional harvester
MMD (µm AED)^[b,c]	19.3 x	18.2 x
GSD^[d]	1.86 x	1.90 x
Average % PM10 ^[e]	18.6	21.3
Average % PM2.5	0.1	0.1
Notes: No statistical differences were detected in means in the same row followed by the same letter (α = 0.05). MMD = mass median diameter. AED = aerodynamic equivalent diameter. GSD = geometric standard deviation. Average % PM10 obtained utilizing eq 2 with d50 = 10 µm and FEC slope = 1.5.

Table 8. Emissions (kg/km²) from harvest treatments (Flory harvester; n = 5 per treatment)

	TSP	True PM 10	True PM 2.5	FRM PM 10	FRM PM 2.5
Emissions
Flory 8550	2,281	436	2	1,034	359
Conventional	3,891	802	5	1,599	280
Reduction	41%	46%*	69%*	35%*	−28%
Significance
Within-subject	0.787	0.201	0.945	0.771	0.813
Between-subject	0.178	0.021	0.050	0.061	0.502
Note: Reductions marked with asterisks were significant at p = 0.10.

Table 9. Meteorological parameters measured onsite during sampling (Weiss-McNair [WM] harvester)

	WM 9800 CA Special harvester			Conventional harvester
	Minimum	Maximum	Average	Minimum	Maximum	Average
Albedo	0.20	0.27	0.24	0.20	0.31	0.24
Relative humidity (%)	12	20	16	14	23	19
Temperature (°C)	30	36	34	28	35	33
Solar radiation (W/m^2)	479	824	690	323	838	692
Wind speed (m/sec)	0.4	2.7	1.7	0.6	2.3	1.7

Table 10. Particle size distribution parameters from TSP filters (Weiss-McNair harvester)

	Weiss-McNair harvester	Conventional harvester
MMD (µm AED)	20.9 x	20.8 x
GSD	1.87 x	1.90 x
Average % PM10	16.0	16.6
Average % PM2.5	0.1	0.1
Notes: No statistical differences were detected in means in the same row followed by the same letter (α = 0.05). MMD = mass median diameter. AED = aerodynamic equivalent diameter. GSD = geometric standard deviation. Average % PM10 obtained utilizing eq 2 with d50 = 10 µm and FEC slope = 1.5.

Table 11. Emissions (kg/km²) from harvest treatments (Weiss-McNair harvester; n = 4 per treatment)

	TSP	True PM 10	True PM 2.5	FRM PM 10	FRM PM 2.5
Emissions
WM 9800 CA Special	5,095	1,036	3	1,453	121
Conventional	6,865	1,137	5	2,628	313
Reduction	26%	9%	29%	45%	61%*
Significance
Within-subject	0.107	0.032	0.226	0.524	0.105
Between-subject	0.394	0.614	0.418	0.127	0.003
Note: Reductions marked with asterisks were significant at p = 0.10.

Table 12. Meteorological parameters measured onsite during sampling (DiAnna cyclone)

	Harvester with cyclone			Conventional harvester
	Minimum	Maximum	Average	Minimum	Maximum	Average
Albedo	0.23	0.28	0.25	0.18	0.40	0.24
Relative humidity (%)	13	18	15	13	38	19
Temperature (°C)	33	37	35	26	36	32
Solar radiation (W/m^2)	448	830	701	187	819	640
Wind speed (m/sec)	1.5	2.4	2.0	0.4	2.6	1.8

Table 13. Particle size distribution parameters from TSP filters (DiAnna cyclone)

	Cyclone retrofit	Conventional harvester
MMD (µm AED)	22.1 x	18.7 y
GSD	1.96 x	1.86 y
Average % PM10	15.5	19.8
Average % PM2.5	0.1	0.1
Notes: No statistical differences were detected in means in the same row followed by the same letter (α = 0.05). MMD = mass median diameter. AED = aerodynamic equivalent diameter. GSD = geometric standard deviation. Average % PM10 obtained utilizing eq 2 with d50 = 10 µm and FEC slope = 1.5.

Table 14. Emissions (kg/km²) from harvest treatments (DiAnna cyclone; n = 5 per treatment)

	TSP	True PM 10	True PM 2.5	FRM PM 10	FRM PM 2.5
Emissions
With cyclone	2,292	337	1	771	14
Conventional	7,871	1,600 y	8	3,156	279
Reduction	71%	79%	88%	76%*	95%*
Significance
Within-subject	0.152	0.352	0.431	0.916	0.879
Between-subject	0.145	0.138	0.357	0.031	0.005
Note: Reductions marked with asterisks were significant at p = 0.10.

Faulkner , W.B. , Downey , D. , Giles , D.K. and Capareda , S.C. 2011 . Evaluation of particulate matter abatement strategies for almond harvest . J. Air Waste Manage. Assoc. , 61 : 409 – 417 . doi: 10.3155/1047-3289.61.4.409

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