Spectroscopic measurements of BrO using direct sun and zenith sky viewing geometries are combined in an optimal estimation retrieval algorithm to obtain tropospheric and stratospheric columns of BrO. ...Twenty‐two twilight periods are investigated over Arrival Heights, Antarctica (77.8°S, 166.7°E) during the polar spring period of 2002. This paper presents the first tropospheric and stratospheric BrO column retrievals from UV‐visible ground‐based measurements for a polar location. A direct comparison is made between stratospheric columns retrieved at 80°, 84°, and 88° solar zenith angles (SZA) from the spectroscopic measurements and those calculated by the SLIMCAT three‐dimensional chemical transport model. The ground‐based column BrO observations are consistent with a SLIMCAT stratospheric Bry loading of 21.2 parts per trillion at 20 km. SLIMCAT reproduces the observed sunrise column BrO increase but does not match the sunset observations, which display less variation. The significant warming of the Antarctic polar stratosphere in 2002 led to highly variable stratospheric columns being observed. The observed column BrO decreased with the transition from vortex to extravortex air on 21 September but did not change much following the return of the vortex on 12 October. For the tropospheric column, an almost normal distribution consistent with a “background” of 0.3 ± 0.3 × 1013 molecules cm−2 is observed from the ground (80°, 84°, and 88° for both sunrise and sunset). A statistically significant “bromine explosion” event (at the 2σ level) was detected at the end of October with a tropospheric column of 1.8 ± 0.1 × 1013 molecules cm−2. The measured tropospheric columns are compared with the tropospheric Model of Atmospheric Transport and Chemistry–Max Planck Institute for Chemistry version model. The tropospheric BrO sunrise column observations can only be explained with an additional bromine source other than decomposition of CH3Br and downward transport of long‐lived bromine from the stratosphere. A comparison with the spaceborne Global Ozone Monitoring Experiment (GOME) found the total columns observed from the ground to be 16–25% smaller than the total columns observed by GOME for SZAs between 80° and 88°.
A large number of volatile and semi-volatile organic compounds from atmospheric particulates (PM
10) have been identified. We have developed and optimised the use of headspace solid phase ...microextraction as a sample concentration method for the analysis of organics in PM
10 using GC/MS. Headspace organics were found to be produced in maximum abundance on heating the particulate samples at 100
°C for 30
min. The most useful sample cooling and headspace extraction times using a PDMS 100
μm fibre were found to be 7 and 10
min, respectively. The boiling points of the extracted organics ranged from 40 to 391
°C and were found to be normally distributed. However, most of the organics (66%) were found to have their boiling point range between 140 and 240
°C. Vapour pressure of the organics ranged from 0.0002 to 10.13
kPa, but 82% were found to be within the range of 0.05–1.0
kPa. Similarly, carbon number varied from C
2–C
24, with 68% of the total number of 86 organics detected being C
8–C
13.
Spectroscopic measurements of BrO using direct sun and zenith‐sky viewing geometries are combined in an optimal estimation retrieval algorithm to obtain tropospheric and stratospheric columns of BrO. ...Seventy‐two twilight periods are investigated over Lauder, New Zealand (45.0°S, 169.7°E), between March 2001 and April 2003. A direct comparison between tropospheric and stratospheric columns retrieved at 80°, 84°, and 87° solar zenith angles (SZAs) from the spectroscopic measurements and those calculated by the three‐dimensional chemical transport model SLIMCAT shows good agreement. The stratospheric Bry loading of 21 pptv from the SLIMCAT calculations is consistent with the ground‐based measurements. The seasonal and diurnal variation of the stratospheric BrO columns evident from the ground‐based measurement retrievals is well described by the SLIMCAT model. The tropospheric column retrievals illustrate a high variability with a mean value of 0.2 pptv if the troposphere is assumed to be well mixed. An upper limit of 0.9 pptv is established for the ubiquitous BrO tropospheric column at 80° under cloud free conditions.
Relationships between weather types and the air pollutants ozone (O
3) and nitrogen oxides
(
NO
x
)
at night are explored through the analysis of two years of data from the east coast of the Auckland ...urban area. Principal component analysis is used to identify synoptic classes and corresponding weather types, while principal component regression is used to assess relationships between these and O
3 and
NO
x
(
NO
+
NO
2
)
concentrations. Three synoptic classes (labelled cyclonic, anticyclonic and intermediate) consisting of seven discrete weather types were identified. Anticyclonic and cyclonic synoptic conditions were strong determinants of O
3 and
NO
x
concentrations. The intermediate class was the most persistent but had less significant effect on O
3 and
NO
x
concentrations. In cyclonic conditions,
NO
x
was low due to increased ventilation.
NO
x
concentration under anticyclonic conditions with cold and relatively dry air from Auckland urban areas was large, while that of O
3 was generally small, as O
3 is efficiently removed as a result of chemical titration with NO in the stable boundary layer. Under these conditions O
3 can also be expected to be removed by dry deposition and
NO
x
removed by the heterogeneous hydrolysis of dinitrogen pentoxide (N
2O
5). In cyclonic conditions and during times when winds from over the ocean prevailed, the concentration of O
3 was relatively high, apparently due to a very weak O
3 titration reaction and intrusion of regional-scale background O
3. Temperature and humidity had no significant effect on nocturnal O
3, while both affected NO
2 concentrations.
Compounds in the headspace of a variety of wool samples and greases have been analysed with the aid of solid phase microextraction using a carboxen-polydimethylsiloxane coated fibre. Volatiles were ...analysed by gas chromatography/mass spectrometry, while sulphur-containing compounds were analysed using gas chromatography/pulsed flame photometric detector.
The volatile organic compounds released from scoured sheep wool and wool grease were investigated in vials under dry and humid conditions between 20 and 40
°C. A laboratory scale scouring apparatus was also used to investigate the emission of volatiles at different stages of the wool scouring process. A variety of volatile compounds, including sulphur-containing compounds, were emitted with their concentration increasing with temperature and humidity in most cases. There was a progressive decrease in the number of volatiles released after various stages of the wool scouring process. Wool grease emitted an assortment of volatile compounds, many of which were also detected in the headspace of scoured wool. Degradation of wool and particularly wool grease is thought to be responsible for the occurrence of the detected compounds.
Use of an odour index helped identify possible contributors to the odour of wool, but unqualified proof remains elusive because of the possibility that compounds present at concentrations below detection limits may have made a contribution.
A major aim of this work was to improve the odour of scoured wool. To achieve this aim two antioxidants were separately incorporated into the wool scouring process. In both cases, this resulted in a reduction of the number of headspace volatile compounds detected, and a distinct improvement in the pleasantness of the odour with an accompanying reduction in the odour intensity.
Recently, atmospheric humic matter or humic-like substances (HULIS) have been found in the water-soluble fraction of atmospheric aerosol sampled at different locations. Most of these locations were ...continental, non-urban sites. Therefore, in this work HULIS was studied in urban and marine environments. The atmospheric concentration varied over a wide range from 0.40 to 5.44 μg m
−
3
, from the clean marine air (Mace Head, Ireland) to the heavily polluted winter urban atmosphere (Christchurch, New Zealand). In terms of carbon, ratio of HULIS was 19–51% of water-soluble organic carbon, and 10–22% of total carbon. Different spectroscopic techniques were applied for the physico-chemical characterisation of HULIS including relative aromaticity and molecular weight. Specific absorbance was observed to be much less variable than specific fluorescence, and consequently UV-VIS spectroscopy at
λ
>
330 nm was recommended for rapid, semi-quantitative determination of HULIS in the water extracts of atmospheric aerosol. Application of a dual filter sampling system at one of the sampling sites has revealed a significant positive sampling artefact which calls for further systematic studies on this subject, and also supports the idea of a secondary organic aerosol formation mechanism of HULIS.
Wintertime PM
10 samples collected in two New Zealand cities (Christchurch and Auckland) have been analysed for total carbon (TC), elemental carbon (EC), organic carbon (OC), water-soluble organic ...carbon (WSOC), and water-insoluble organic carbon (WIOC) as well as major inorganic ions. Christchurch, which is heavily influenced by residential wood and coal burning in winter, showed significantly higher ambient concentrations of carbonaceous materials than Auckland whose major sources of aerosols are sea-salt and vehicular emissions. In Christchurch, the mean concentrations of TC, EC, WSOC, and WIOC were 21, 6.0, 7.0 and 7.6
μg
m
−3, respectively. In contrast, those of Auckland were 5.0, 2.0, 1.3 and 1.7
μg
m
−3, respectively. On average, total carbonaceous materials (EC, water-soluble organic matter and water-insoluble organic matter) accounted for about 70% of PM
10 mass in Christchurch but less than 30% in Auckland. Moreover, WSOC/EC and nss-K
+/EC mass ratios in Christchurch were found to be substantially higher than those of Auckland. In contrast, nss-SO
4
2−, NO
3
− and nss-Ca
2+ concentrations in Auckland were dramatically enhanced relative to carbonaceous materials. This study suggests that fresh emissions from solid fuel burning are significantly more enriched with WIOC than WSOC, although a significant fraction of WSOC may be a secondary atmospheric product. It is estimated that only one-fifth to one-quarter of the measured OC was attributable to secondary organic aerosols in the two cities in winter.
A brown haze, which builds up over Auckland, New Zealand under calm and cold weather conditions, causes public concern. This study identifies the major sources of this brown haze using variations in ...the elemental composition of airborne particulate matter between those collected during brown haze days, and normal days in the year 2001. Airborne particulate matter was collected in a site in southeast Auckland, using a versatile air pollution sampler (VAPS) and a PM
10 hi-volume sampler. The elemental composition of the samples, collected using the hi-volume sampler, was quantitatively determined for 14 elements using ICP/MS. The elemental composition of the coarse and fine fractions of the particulate matter collected using the VAPS, was quantitatively determined using ion beam analysis for 16 elements. Elemental carbon was quantitatively determined by a light reflection/transmission technique. For source determination, the VAPS was found to be more useful that the hi-volume sampler.
Enrichment factors (EF) for each element of the PM
10 samples were calculated to identify the sources. Further, principal component factor analysis with Varimax rotation was performed using some selected elements in the coarse and fine fractions of particulate samples collected using the VAPS to identify major sources of PM
10 in Auckland. The analysis yielded six significant sources: sea spray, suspended soil/road dust, fine soil, domestic emissions, diesel, and petrol emissions. EF values for brown haze samples revealed that diesel emissions were the major sources responsible for the build-up of brown haze. Coal combustion emissions were also found to contributed, but to a lesser extent. Furthermore, source apportionment using absolute principal component analysis on brown haze and normal days confirmed that accumulation of diesel emissions contributed most to the appearance of brown haze and coal combustion emissions to a lesser extent.
Background: Two‐point discrimination, static and dynamic, has long been used as an assessment tool for tactile gnosis, and to assess recovery after repair of a peripheral nerve. While use of a bent ...paperclip with a specified intertip distance as the assessment device has been described, no research has been performed on the accuracy of setting this distance by hand and eye alone. The aim of the present study was to demonstrate this accuracy.
Methods: Five orthopaedic registrars, four residents and three clinic nurses performed static and dynamic two‐point discrimination testing on each other. They set the tip distance by hand and eye by bending a paperclip such that the distance between the two ends was their best approximation of 5 mm and then 10 mm. The testing was repeated after 7 days, n = 264 for each tip distance.
Results: Two‐sample t‐tests showed no significant difference (P > 0.53−0.93) between tip distance setting performed by registrars, nurses and residents; while single sample t‐test showed a statistically significant difference (P < 0.0001) between the attempted tip distance and the overall mean tip distance achieved at 5 mm and 10 mm.
Conclusion: Statistical analysis showed that the single sample t‐test could be discarded. Static and dynamic two‐point discrimination testing with a paperclip set by hand and eye is therefore an accurate and reproducible test capable of being administered by both medical and non‐medical staff, and is suitable for inclusion in a peripheral nerve repair testing protocol.
The results of one year's measurements (typically a two week sampling campaign in each season) of the concentrations of eight major water soluble ions, namely Na
+, NH
4
+, K
+, Mg
2+, Ca
2+, Cl
−, ...NO
3
− and SO
4
2−, in atmospheric aerosols collected in three New Zealand cities (Auckland, Christchurch and Hamilton) are presented. The data has provided important information on particulate soluble ion profiles in New Zealand urban areas and revealed some useful trends.
A significant correlation has been found between the average meteorological conditions in a sampling campaign and the average particulate concentrations of some of these soluble ions in the campaign. For example, average particulate NO
3
− concentration in a campaign was found to correlate well with the average calm or weak wind duration percentage in the campaign, and the average concentrations of Na
+, Mg
2+ and Cl
− related closely to the average wind pattern and rainfall in the campaign.
Significant site and seasonal variations have been observed with Hamilton having the lowest overall concentrations of all the soluble ions in the particles sampled. On average all sites had the highest particulate concentrations of Na
+, Mg
2+ and Cl
− in the summer but the highest particulate concentrations of NH
4
+ and non-sea-salt Ca
2+ (nss-Ca
2+) in the winter. The possible sources of PM
10 mass have been deduced and in particular the relative contribution of sea salts to PM
10 mass in the cities are reported.
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