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Opis: High-spectral-resolution lidar (HSRL) is a powerful tool for aerosol measurements. With/without laser seeding technique in the transmitted laser, the HSRL can be distinguished as the single-longitudinal-mode (SLM) HSRL or the multi-longitudinal-mode (MLM) HSRL, and the Mach-Zehnder interferometer (MZI) with periodic transmittance function can be used as the spectral discriminator in both the SLM HSRL and MLM HSRL. To in-depth knowledge of the respective advantages of the SLM HSRL and MLM HSRL for measuring aerosol optical properties, the working principle, optimal parameter setting, and detection performance of the SLM HSRL and MLM HSRL are analyzed and discussed in detail, respectively. The working principle of the SLM HSRL and MLM HSRL indicate that the effective transmittance of MZI is the important parameter of data retrieval, the main source of retrieval uncertainties, and the key factor of MZI optical path difference (OPD) settings. To ensure that the MZI can achieve the preferable separation for aerosol Mie scattering signals and molecular Rayleigh scattering signals, the optimal OPDs of MZI are set at 165 mm and 1000 mm in the SLM HSRL and MLM HSRL from the aspects of the effective transmittance of MZI and the spectral discrimination ratio (SDR). Besides, to analyze the influence of frequency difference and divergence angle for the detection performance of HSRL, the effective transmittance of MZI and SDR are simulated and the results show that the MLM HSRL has higher requirements for the environmental parameters and the echo beam collimation than the SLM HSRL. Moreover, the HSRLs with SLM and MLM transmitted lasers are constructed in Xi'an for measuring aerosol optical properties. The preliminary measurement results show that the range square corrected signal (RSCS) of Rayleigh channel is smaller than that of Mie channel in both the SLM HSRL and MLM HSRL, while the difference between RSCS of Rayleigh channel and RSCS of Mie channel in the SLM HSRL is larger than that in the MLM HSRL, and the detection range of the SLM HSRL is lower than that of the MLM HSRL.
Ključne besede: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Objavljeno v RUNG: 28.02.2024; Ogledov: 2348; Prenosov: 5
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Ključne besede: black carbon, nitrogen oxides, emission ratio, Arabian Gulf region
Objavljeno v RUNG: 08.07.2021; Ogledov: 3604; Prenosov: 0
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Opis: Polycyclic aromatic hydrocarbons (PAHs) are compounds known for their adverse effects on human health. Many of them are proven carcinogens, especially those with 5 and 6 aromatic rings, which under normal tropospheric conditions are found in the particle-phase. Benzo(a)pyrene (BaP) is often measured as their general representative. Sarajevo, the capital of Bosnia and Herzegovina, is among the European cities with the poorest air quality. However, in Sarajevo PAHs are neither routinely measured within the air quality monitoring network nor have been a subject of extended, continuous field studies during the most polluted cold periods of the year. The capital of Croatia, Zagreb, is located approximately 300 km air distance north-west from Sarajevo. PAH mass concentrations in Zagreb have been measured continuously since 1994 within air quality monitoring networks. During winter 2017/2018, the SAFICA project (Sarajevo Canton Winter Field Campaign 2018) was carried out in order to characterize the chemical composition of organic and inorganic aerosol in the Sarajevo Canton. This paper presents the results of PAH measurements in the cities of Sarajevo and Zagreb at one urban location per city. Daily (24 h), continuous samples of PM10 (particulate matter with aerodynamic diameters ≤10 μm) were collected during heating season, from December 27, 2017 to February 27, 2018. Mass concentrations of eleven particle-phase PAHs in Sarajevo and Zagreb from filter samples collected during the same period were compared. The average BaP ambient mass concentrations in Sarajevo and Zagreb were 6.93 ng m−3 and 3.11 ng m−3, respectively. The contribution of BaP to the total PAH mass concentration was similar at both locations (11%). However, much higher contributions of particle-phase fluoranthene and pyrene were found in Sarajevo. Contributions of individual PAH, diagnostic ratios and factor analysis indicate that combustion of gasoline and diesel from vehicle traffic are a potential source of PAHs at both locations, as well as combustion of other liquid fossil fuels (petroleum and fuel oil). Wood burning was occasionally indicated as a PAH emission source in Zagreb, while in Sarajevo the contribution of PAHs from wood and coal combustion was more evident. Calculated value for total carcinogenic potency (TCP) of PAHs, which was estimated using toxic equivalence factors from the literature, in PM10 samples collected in Sarajevo was more than twice higher than in Zagreb (10.6 ng m−3 and 4.7 ng m−3, respectively). BaP had the highest contribution to the TCP at both locations (69 and 67%).
Ključne besede: carcinogenic potency, diagnostic ratio, factor analysis, PM10, polycyclic aromatic hydrocarbons
Objavljeno v RUNG: 09.04.2021; Ogledov: 3639; Prenosov: 0
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Opis: Anaerobic digestion of brewery spent grain as a mono-substrate was studied. Brewery spent grain is a substrate consisting largely of cellulose, hemicellulose and lignin, which are difficult to degrade anaerobically, mostly due to the presence of degradation products, such as phenolic compounds, which cause process inhibition. Therefore, a two-stage system was used for anaerobic digestion. Anaerobic digestion was phase separated in a solid-state anaerobic digestion reactor, where microbiological hydrolysis and acidogenesis occurred and in a granular biomass reactor where mostly methanogenesis was performed. The overall process exhibited total solids degradation efficiency between 75.9 and 83.0 %. Average specific biogas production was 414±32 L/kg, whereas biomethane production was 224±34 L/kg of added total solids. Granular biomass after adaptation exhibited stable operation at substrate C/N ratios in range 0.16 – 4.68. p-cresol was present in concentrations up to 45 mg/L and during the process was successfully degraded by granular biomass. The excellent adaptability of granular biomass was confirmed by 68.2 % shift in bacterial and a 31.8 % shift in archaeal community structure in a granular biomass reactor. The structure of the bacterial community from granular biomass reactor and solid-state anaerobic digestion reactor remained 79.4 % similar at the end of the experiment, whereas archaeal community was only 31.6 % similar. The process exhibited stable operation for 198 days, which shows that brewery spent grain can be successfully anaerobically digested and used for biogas production.
Ključne besede: biogas production, brewery spent grain, C/N ratio, dry digestion, microbial biomass, solid-state anaerobic digestion
Objavljeno v RUNG: 18.08.2017; Ogledov: 5789; Prenosov: 0
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