The reduction of ammonia (NH3) emissions is urgently needed due to its role in aerosol nucleation and growth causing haze formation during its conversion into ammonium (NH4(+)). However, the relative contributions of individual NH3 sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH3 in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of (15)N (expressed using δ(15)N values) of NH4(+) in fine particles varies with the development of haze episodes, ranging from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity: ∼ 40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity: 70-90%). After accounting for the isotope exchange between NH3 gas and aerosol NH4(+), the δ(15)N value of the initial NH3 during hazy days is found to be -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH3 during hazy days in urban Beijing. This work demonstrates the analysis of δ(15)N values of aerosol NH4(+) to be a promising new tool for partitioning atmospheric NH3 sources, providing policy makers with insights into NH3 emissions and secondary aerosols for regulation in urban environments.

Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from 15 N-Stable Isotope in Size-Resolved Aerosol Ammonium

Liquid scintillation counting (LSC) is a major technique not only for measurement of pure beta emitting radionuclides, but also radionuclides decay by electron capture and alpha emission. Although it is a conventional radiometric technique, but still a competitive techniques for the measurement of many radionuclides. This paper summaries the major development of this measurement technique in instrumentation, methodology and applications in the past decades. The progresses in the instrumentation and methodology mainly focus on the commercialization of triple-to-double coincidence ratio based LSC techniques and its application in the determination of different radionuclides. An overall review and discussion on the LSC based analytical methods for the determination of major radionuclides in environmental researches, decommissioning of nuclear faculties and nuclear application are presented, in both measurement techniques and sample preparation using radiochemical separation. Meanwhile the problems and challenges in the development and application of the LSC are also discussed.

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Liquid scintillation counting for determination of radionuclides in environmental and nuclear application

Spatial-temporal heterogeneity of air pollution and its relationship with meteorological factors in the Pearl River Delta, China

A review of measurement methodologies and their applications to environmental 90Sr.

Recent trends in the analysis of trace elements in the field of environmental research: A review

Sequential analyses of actinides in large-size soil and sediment samples with total sample dissolution.

Rapid determination of radium-224/226 in seawater sample by alpha spectrometry.

Quantification of secondary particle loading during a heavy air pollution event in Beijing: A simplified method based on coal emission indicators

Effects of sodium salicylate on the determination of Lead-210/Bismuth-210 by Cerenkov counting.

A rapid, low cost method for the determination of 90Sr in leaching solution of cement solidification was developed using triple-to-double coincidence ratio (TDCR) Cerenkov counting of 90Y. In this method, 90Y was separated from sample matrix and interfering radionuclides through two co-precipitation steps with hydrous titanium oxide followed by yttrium fluoride (YF3) precipitation. After dissolution of the YF3 precipitate, 90Y was measured by TDCR Cerenkov technique. The performance of the method was examined using a series of the samples spiked with various activities of 90Sr ranging from 1.75 to 32 Bq L−1, along with the procedural blanks. The mean chemical recovery of Y was 86 ± 8%. The measured 90Sr agreed well with the expected 90Sr within an acceptable deviation of ~10%. The minimum detectable concentration was about 0.3 Bq L−1 for 0.2 L sample with a counting time of 5400 s by a Hidex 300 SL TDCR liquid scintillation counter. The overall decontamination coefficients were determined to be >5400 for 60Co, >5300 for 137Cs, >14,500 for 40K and 4500 ± 580 for 210Pb/210Bi, respectively.

Lijuan Song

Papers

Sequential analyses of actinides in large-size soil and sediment samples with total sample dissolution.

Rapid determination of radium-224/226 in seawater sample by alpha spectrometry.

Quantification of secondary particle loading during a heavy air pollution event in Beijing: A simplified method based on coal emission indicators

Effects of sodium salicylate on the determination of Lead-210/Bismuth-210 by Cerenkov counting.

A rapid method for determining 90Sr in leaching solution from cement solidification of low and intermediate level radioactive wastes