Pieter G. van Zyl

Bio: Pieter G. van Zyl is an academic researcher from North-West University. The author has contributed to research in topics: Aerosol & Air quality index. The author has an hindex of 19, co-authored 57 publications receiving 1164 citations. Previous affiliations of Pieter G. van Zyl include University of Helsinki.

An overview of the first decade of Polly NET : an emerging network of automated Raman-polarization lidars for continuous aerosol profiling

Abstract: . A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar network PollyNET. This network consists of portable, remote-controlled multiwavelength-polarization-Raman lidars (Polly) for automated and continuous 24/7 observations of clouds and aerosols. PollyNET is an independent, voluntary, and scientific network. All Polly lidars feature a standardized instrument design with different capabilities ranging from single wavelength to multiwavelength systems, and now apply unified calibration, quality control, and data analysis. The observations are processed in near-real time without manual intervention, and are presented online at http://polly.tropos.de/ . The paper gives an overview of the observations on four continents and two research vessels obtained with eight Polly systems. The specific aerosol types at these locations (mineral dust, smoke, dust-smoke and other dusty mixtures, urban haze, and volcanic ash) are identified by their Angstrom exponent, lidar ratio, and depolarization ratio. The vertical aerosol distribution at the PollyNET locations is discussed on the basis of more than 55 000 automatically retrieved 30 min particle backscatter coefficient profiles at 532 nm as this operating wavelength is available for all Polly lidar systems. A seasonal analysis of measurements at selected sites revealed typical and extraordinary aerosol conditions as well as seasonal differences. These studies show the potential of PollyNET to support the establishment of a global aerosol climatology that covers the entire troposphere.

Rapid changes in biomass burning aerosols by atmospheric oxidation

Abstract: Partially funded by the Academy of Finland (132640, Finnish Centre of Excellence 141135), the Saastamoinen Foundation, and the North-West University (South Africa)

An air quality assessment in the industrialised western Bushveld Igneous Complex, South Africa

Abstract: South Africa has the largest industrialised economy in Africa, with significant mining and metallurgical activities. A large fraction of the South African mineral assets is concentrated in the Bushveld Igneous Complex (BIC), with the western limb being the most exploited. Because the majority of the world’s platinum is produced in the BIC, this area is also of international interest. There are some indications that the western BIC should be considered an air pollution hotspot; however, inadequate data exist to substantiate these claims scientifically. To partially address this knowledge gap, a comprehensive air quality monitoring station was operated for more than 2 years in this area. Meteorological parameters, trace gas concentrations and total mass concentration of particulate matter up to 10 µm in size (PM 10 ) were measured. Compared with South African and European ambient air quality standards, SO 2 , NO 2 and CO concentrations were generally acceptable. The major sources of SO 2 were identified as high-stack industry emissions, while household combustion from semi-formal and informal settlements was identified as the predominant source of NO 2 and CO. In contrast, O 3 exceeded the 8-h moving average more than 322 times per year. The main contributing factor was identified to be the influx of regional air masses, with high O 3 precursor concentrations. PM 10 exceeded the current South African 24-h standard 6.6 times per year, the future (2015) standard 42.3 times per year and the European standard more than 120 times per year. The main source of PM 10 was identified as household combustion from semi-formal and informal settlements. The findings clearly indicate that atmospheric O 3 and PM 10 levels in the western BIC need to be addressed to avoid negative environmental and human health impacts.

Spatial and temporal assessment of gaseous pollutants in the Highveld of South Africa

Abstract: Diverse natural and anthropogenic activities in the Highveld of South Africa contribute to elevated levels of inorganic and organic gaseous pollutant species. The primary aims of this investigation were to determine spatial and temporal distributions of nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ) and ozone (O 3 ), as well as benzene, toluene, ethylbenzene and xylene (BTEX) in this area. Sampling was conducted on a monthly basis for a year at eight strategically selected sites. The highest NO 2 , SO 2 and BTEX concentrations were measured at sites with significant local sources and/or sites impacted by more remote sources, as indicated by overlay back trajectories. O 3 concentrations were found to be lower at sites with high levels of NO 2 , SO 2 and BTEX. NO 2 and SO 2 peaked during winter, while O 3 peaked in spring. NO 2 and SO 2 temporal concentration variations were ascribed to differences in seasonal meteorological conditions, as well as additional sources in winter. The O 3 peak coincided with a seasonal CO peak, which was identified as an important precursor for O 3 formation. No distinct seasonal trend was observed for BTEX. The annual average concentrations for SO 2 , NO 2 , O 3 and benzene were below the South African annual standards at all sites.

Re-evaluating the NO2 hotspot over the South African Highveld

Abstract: Globally, numerous pollution hotspots have been identified using satellite-based instruments. One of these hotspots is the prominent NO 2 hotspot over the South African Highveld. The tropospheric NO 2 column density of this area is comparable to that observed for central and northern Europe, eastern North America and south-east Asia. The most well-known pollution source in this area is a large array of coal-fired power stations. Upon closer inspection, long-term means of satellite observations also show a smaller area, approximately 100 km west of the Highveld hotspot, with a seemingly less substantial NO 2 column density. This area correlates with the geographical location of the Johannesburg–Pretoria conurbation or megacity, one of the 40 largest metropolitan areas in the world. Ground-based measurements indicate that NO 2 concentrations in the megacity have diurnal peaks in the early morning and late afternoon, which coincide with peak traffic hours and domestic combustion. During these times, NO 2 concentrations in the megacity are higher than those in the Highveld hotspot. These diurnal NO 2 peaks in the megacity have generally been overlooked by satellite observations because the satellites have fixed local overpass times that do not coincide with these peak periods. Consequently, the importance of NO 2 over the megacity has been underestimated. We examined the diurnal cycles of NO 2 ground-based measurements for the two areas – the megacity and the Highveld hotspot – and compared them with the satellite-based NO 2 observations. Results show that the Highveld hotspot is accompanied by a second hotspot over the megacity, which is of significance for the more than 10 million people living in this megacity.

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

This is How the Discussion Started

Abstract: A copy of Guangbo jiemu bao [Broadcast Program Report] was being passed from hand to hand among a group of young people eager to be the first to read the article introducing the program "What Is Revolutionary Love?" It said: "… Young friends, you are certainly very concerned about this problem'. So, we would like you to meet the young women workers Meng Xiaoyu and Meng Yamei and the older cadre Miss Feng. They are the three leading characters in the short story ‘The Place of Love.’ Through the description of the love lives of these three, the story induces us to think deeply about two questions that merit further examination.

Chemistry of atmospheric brown carbon.

Abstract: Organic carbon (OC) accounts for a large fraction of atmospheric aerosol and has profound effects on air quality, atmospheric chemistry and climate forcing. Molecular composition of the OC and its evolution during common processes of atmospheric aging have been a subject of extensive research over the last decade (see reviews of Ervens et al.,1 Hallquist et al.,2 Herckes et al.,3 Carlton et al.,4 Kroll and Seinfeld,5 Rudich et al.,6 and Kanakidou et al.7). Even though many fundamental advances have been reported in these studies, our understanding of the climate-related properties of atmospheric OC is still incomplete and the specific ways in which OC impacts atmospheric environment and climate forcing are just beginning to be understood. This review covers one topic of particular interest in this area –environmental chemistry of light-absorbing aerosol OC and its impact on radiative forcing.