Work

Characterization of water-soluble inorganic ions and carbonaceous aerosols in the urban atmosphere in Amman, Jordan

Year: 2024

Type: article

Abstract: The urban particulate matter (PM) carbonaceous and water-soluble ions were investigated in Amman, Jordan during May 2018–March 2019. The PM 2.5 total carbon (TC) annual mean was 7.6 ± 3.6 μg/m 3 (organic carbon (OC) 5.9 ± 2.8 μg/m 3 and elemental carbon (EC) 1.7 ± 1.1 μg/m 3 ), which was about 16.3% of the PM 2.5 . The PM 10 TC annual mean was 8.4 ± 3.9 μg/m 3 (OC 6.5 ± 3.1 μg/m 3 and elemental carbon (EC) 1.9 ± 1.1 μg/m 3 ), about 13.3% of the PM 10 . The PM 2.5 total water-soluble ions annual mean was 7.9 ± 1.9 μg/m 3 (about 16.9%), and that of the PM 10 was 10.1 ± 2.8 μg/m 3 (about 16.0%). The minor ions (F − , NO 2 − , Br − , and PO 4 3− ) constituted less than 1% in the PM fractions. The significant fraction was for SO 4 2− (PM 2.5 4.7 ± 1.6 μg/m 3 (10.0%) and PM 10 5.3 ± 1.9 μg/m 3 (8.3%)). The NH 4 + had higher amounts of PM 2.5 (1.3 ± 0.6 μg/m3; 2.7%) than that PM 10 (0.9 ± 0.4 μg/m 3 ; 1.4%). During sand and dust storm (SDS) events, TC, Cl − , and NO 3 − were doubled in PM, SO 4 2− did not increase significantly, and NH 4 + slightly decreased. Regression analysis revealed: (1) carbonaceous aerosols come equally from primary and secondary sources, (2) about 50% of the OC came from non-combustion sources, (3) traffic emissions dominate the PM, (4) agricultural sources have a negligible effect, (5) SO 4 2− is completely neutralized by NH 4 + in the PM 2.5 but there could be additional reactions involved in the PM 10 , and (6) (NH 4 ) 2 SO 4 , was the major species formed by SO 4 2− and NH 4 + instead of NH 4 HSO 4 . It is recommended to perform long-term sampling and chemical speciation for the urban atmosphere in Jordan. • carbonaceous aerosols in Amman come equally from primary and secondary sources. • about 50% of the OC came from non-combustion sources. • traffic emissions dominate the PM. • agricultural sources have a negligible effect. • SO 4 2− is completely neutralized by NH 4 + in the PM 2.5 .

Source: Physics and Chemistry of the Earth Parts A/B/C

DOI: 10.1016/j.pce.2024.103783