Intercomparison of Thermal–Optical Methods for the Determination of Organic and Elemental Carbon: Influences of Aerosol Composition and Implications

Zeta potential is frequently used to examine the colloidal stability of particles and macromolecules in liquids. Recently, it has been suggested that zeta potential can also play an important role for grouping and read-across of nanoforms in a regulatory context. Although the measurement of zeta potential is well established, only little information is reported on key metrological principles such as validation and measurement uncertainties. This contribution presents the results of an in-house validation of the commonly used electrophoretic light scattering (ELS) and the relatively new particle tracking analysis (PTA) methods. The performance characteristics were assessed by analyzing silica and polystyrene reference materials. The ELS and PTA methods are robust and have particle mass working ranges of 0.003 mg/kg to 30 g/kg and 0.03 mg/kg to 1.5 mg/kg, respectively. Despite different measurement principles, both methods exhibit similar uncertainties for repeatability (2%), intermediate precision (3%) and trueness (4%). These results confirm that the developed methods can accurately measure the zeta potential of silica and polystyrene particles and can be transferred to other laboratories that analyze similar types of samples. If direct implementation is impossible, the elaborated methodologies may serve as a guide to help laboratories validating their own methods.

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XXV.—The Determination of Temperature Gradients over the Greenland Ice Sheet by Optical Methods

Proceedings of the Royal Society of Edinburgh Section A Mathematical and Physical Sciences ◽

10.1017/s0080454100007597 ◽

1957 ◽

Vol 64 (4) ◽

pp. 381-397

Author(s):

R. A. Hamilton

Keyword(s):

Temperature Gradient ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Temperature Gradients ◽

Lower Atmosphere ◽

Optical Methods ◽

Snow Surface ◽

Vertical Angle ◽

Gradient Measurements

SynopsisThe temperature gradient in the lower atmosphere can be directly determined by measuring the optical refractive index of the air. This method is suitable for use on the Greenland ice sheet where errors introduced by water vapour are small, and where the strong solar radiation reflected by the snow surface makes it difficult to measure temperature differences over height differences of about I metre.The refraction was measured by observing the apparent vertical angle of each of a set of targets at distances up to 4 km. from a theodolite. The refraction was found to vary linearly with the distance of the target. The true vertical angle to the targets was determined when a second theodolite was available and reciprocal sights could be taken with it from the site of target to the fixed theodolite. The true vertical angle varied with time due to slow descent of the theodolite as the firn slumped; a correction for this was made. The standard error of the temperature gradient measurements was about 1.5 × 10−2 C.° per metre. It is considered that the method could be developed and improved so that over a range of only 100 metres temperature gradients could be measured to an accuracy of about 0·1° C. per metre.

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A simplified empirical method for determination of aerosol hygroscopicity and composition

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-23627-2010 ◽

2010 ◽

Vol 10 (10) ◽

pp. 23627-23656

Author(s):

C. H. Chan ◽

A. Y. S. Cheng ◽

A. Viseu

Keyword(s):

Atmospheric Aerosols ◽

Climate Model ◽

Empirical Method ◽

Radiation Budget ◽

Cloud Formation ◽

Monthly Variation ◽

Aerosol Composition ◽

Remote System ◽

Aerosol Hygroscopicity

Abstract. Atmospheric aerosols have substantial influence on the Earth's radiation budget, visibility, cloud formation and precipitation. The aerosol hygroscopicity and the composition of aerosols are of vital importance for solar radiation budget calculation, cloud formation mechanism, and measurement of aerosol spatiotemporal distribution through remote sensing, such as Lidar, MODIS and sun/star photometer. In this paper, hourly averaged records of humidity, visibility and aerosol concentration, conducted in Macao, P.R.C. from 1 February 2006 to 31 December 2008 (LT), are used to estimate aerosol hygroscopicity and composition with a simplified empirical method. The result of monthly variation of aerosol hygroscopicity indicates the important role of aerosol composition on optical properties, which is in agreement with the previous study. This aerosol composition pattern is also consistent with the Asiatic Monsoon pattern and vicinity, such as Hong Kong. The monthly variation of aerosol hygroscopicity and composition also shows the necessity to consider such a factor for the aerosols monitoring by remote system and aerosols forcing simulated by climate model.

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Methods for determination of elemental carbon in ambient air

Environmental Monitoring and Assessment ◽

10.1007/bf00394353 ◽

1990 ◽

Vol 14 (1) ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Wojciech Mniszek ◽

Janusz Kolarczyk ◽

Antoni Hanusik

Keyword(s):

Elemental Carbon ◽

Ambient Air

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Determination of organic and elemental carbon connections on removal segments of atmospheric impurities

Оптика атмосферы и океана ◽

10.15372/aoo20171010 ◽

2017 ◽

Vol 30 (10) ◽

pp. 878-882

Author(s):

V.F. Raputa ◽

S.A. Popova ◽

V.I. Makarov ◽

T.V. Yaroslavtseva

Keyword(s):

Elemental Carbon

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Field test of available methods to measure remotely SO<sub>x</sub> and NO<sub>x</sub> emissions from ships

Atmospheric Measurement Techniques ◽

10.5194/amt-7-2597-2014 ◽

2014 ◽

Vol 7 (8) ◽

pp. 2597-2613 ◽

Cited By ~ 24

Author(s):

J. M. Balzani Lööv ◽

B. Alfoldy ◽

L. F. L. Gast ◽

J. Hjorth ◽

F. Lagler ◽

...

Keyword(s):

Field Studies ◽

Emission Factors ◽

Sulphur Content ◽

Nox Emission ◽

Optical Methods ◽

Optical Absorption Spectroscopy ◽

Open Sea ◽

Remote Measurements ◽

Convenient Technique

Abstract. Methods for the determination of ship fuel sulphur content and NOx emission factors based on remote measurements have been compared in the harbour of Rotterdam and compared to direct stack emission measurements on the ferry Stena Hollandica. The methods were selected based on a review of the available literature on ship emission measurements. They were either optical (LIDAR, Differential Optical Absorption Spectroscopy (DOAS), UV camera), combined with model-based estimates of fuel consumption, or based on the so called "sniffer" principle, where SO2 or NOx emission factors are determined from simultaneous measurement of the increase of CO2 and SO2 or NOx concentrations in the plume of the ship compared to the background. The measurements were performed from stations at land, from a boat and from a helicopter. Mobile measurement platforms were found to have important advantages compared to the land-based ones because they allow optimizing the sampling conditions and sampling from ships on the open sea. Although optical methods can provide reliable results it was found that at the state of the art level, the "sniffer" approach is the most convenient technique for determining both SO2 and NOx emission factors remotely. The average random error on the determination of SO2 emission factors comparing two identical instrumental set-ups was 6%. However, it was found that apparently minor differences in the instrumental characteristics, such as response time, could cause significant differences between the emission factors determined. Direct stack measurements showed that about 14% of the fuel sulphur content was not emitted as SO2. This was supported by the remote measurements and is in agreement with the results of other field studies.

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