| 1. |
- Yue, Siyao, et al.
(författare)
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Brown carbon from biomass burning imposes strong circum-Arctic warming
- 2022
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Ingår i: ONE EARTH. - : Elsevier BV. - 2590-3330 .- 2590-3322. ; 5:3, s. 293-304
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Tidskriftsartikel (refereegranskat)abstract
- Rapid warming in the Arctic has a huge impact on the global environment. Atmospheric brown carbon (BrC) is one of the least understood and uncertain warming agents due to a scarcity of observations. Here, we performed direct observations of atmospheric BrC and quantified its light-absorbing properties during a 2 month circum-Arctic cruise in summer of 2017. Through observation-constrained modeling, we show that BrC, mainly originated from biomass burning in the mid-to high latitudes of the Northern Hemisphere (similar to 60%), can be a strong warming agent in the Arctic region, especially in the summer, with an average radiative forcing of-90 mW m(-2) (similar to 30% relative to black carbon). As climate change is projected to increase the frequency, intensity, and spread of wildfires, we expect BrC to play an increasing role in Arctic warming in the future.
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| 2. |
- Herbst, Andreas, et al.
(författare)
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Different types of acid-base changes at birth, fetal heart rate patterns, and infant outcome at 4 years of age
- 1997
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 1600-0412 .- 0001-6349. ; 76:10, s. 953-958
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To study the relationship between different types of acidemia in umbilical artery blood at birth, fetal heart rate (FHR) patterns during labor, and infant long-term outcome. METHODS: Case-control study of 48 infants with pure high base deficit (base deficit (BD) > or = 12 mmol/L and pCO2 < 8.0 kPa), 51 with mixed acidemia (BD > or = 12 mmol/L and pCO2 > or = 8.0 kPa), born at or after term, and controls matched for maternal age, parity, and gestational age at birth. FHR patterns during labor and the results of developmental screening at age 4 were compared between the groups. RESULTS: Late decelerations were associated with pure high base deficit and complicated variable decelerations with mixed acidemia. Both types of acidemia were correlated with Apgar scores below 7 at 1 minute, and mixed acidemia with more admissions to the neonatal intensive care unit. Developmental screening at age 4 years showed no significant differences between infants with mixed acidemia or pure high base deficit and controls. Twelve infants with mixed acidemia and six controls had deficits in language/speech development. CONCLUSIONS: Late decelerations may be an indicator of a metabolic component of acidemia and complicated variable decelerations an indicator of mixed acidemia. The higher rate of admissions to the neonatal intensive care unit in cases with mixed acidemia may suggest that a concomitant hypercapnia (resulting in lower pH) in metabolic acidemia at birth may be of importance for the outcome. A possible relation between acidemia at birth and deficits in speech/language development should be further evaluated.
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| 3. |
- Ren, Hong, et al.
(författare)
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Measurement report: Vertical distribution of biogenic and anthropogenic secondary organic aerosols in the urban boundary layer over Beijing during late summer
- 2021
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Ingår i: ATMOSPHERIC CHEMISTRY AND PHYSICS. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:17, s. 12949-12963
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Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) plays a significant role in atmospheric chemistry. However, little is known about the vertical profiles of SOA in the urban boundary layer (UBL). This knowledge gap constrains the SOA simulation in chemical transport models. Here, the aerosol samples were synchronously collected at 8, 120, and 260m based on a 325m meteorological tower in Beijing from 15 August to 10 September 2015. Strict emission controls were implemented during this period for the 2015 China Victory Day parade. Here, we observed that the total concentration of biogenic SOA tracers increased with height. The fraction of SOA from isoprene oxidation increased with height, whereas the fractions of SOA from monoterpenes and sesquiterpenes decreased, and 2,3-dihydroxy-4-oxopentanoic acid (DHOPA), a tracer of anthropogenic SOA from toluene oxidation, also increased with height. The complicated vertical profiles of SOA tracers highlighted the need to characterize SOA within the UBL. The mass concentration of estimated secondary organic carbon (SOC) ranged from 341 to 673 ngC m(-3). The increase in the estimated SOC fractions from isoprene and toluene with height was found to be more related to regional transport, whereas the decrease in the estimated SOC from monoterpenes and sesquiterpene with height was more subject to local emissions. Emission controls during the parade reduced SOC by 4 %-35 %, with toluene SOC decreasing more than the other SOC. This study demonstrates that vertical distributions of SOA within the UBL are complex, and the vertical profiles of SOA concentrations and sources should be considered in field and modeling studies in the future.
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