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Bouwman H.,North West University South Africa | Viljoen I.M.,North West University South Africa | Quinn L.P.,North West University South Africa | Quinn L.P.,National Metrology Institute of South Africa
Environmental Research | Year: 2013

We investigated the presence, levels, relationships, and risks of HCHs, DDTs, chlordanes, mirex, PCBs, and brominated flame retardants (BFRs) in terrestrial and aquatic bird eggs from an area in South Africa where DDT is used for malaria control. We found one of the highest σDDT levels reported this century; 13. 000. ng/g. wm (wet mass) in Grey Heron eggs which exceeds critical levels for reproductive success (3000. ng/g. wm) calculated for Brown Pelicans, with a no-effect level estimated at 500. ng/g. wm. Even higher σDDT levels at 16. 000. ng/g. wm were found in House Sparrow eggs (possibly the highest ever recorded for sparrows), with a maximum of 24. 400. ng/g. wm. Significant eggshell thinning in Cattle Egrets (33% between thickest and thinnest) was associated with increased levels of p,. p'-DDT and p,. p'-DDE. There were indications of unknown use of DDT and lindane. Relative to DDT, PCBs and BFRs levels were quite low. Ordinated data showed that different terrestrial pollutant profiles converged to a homogenised aquatic profile. Converging profiles, high levels of DDT in heron and sparrow eggs, and thinning eggs shells, indicate risk and impacts at release, in the aquatic environment, and in between. If characteristic life-strategies of birds in warm areas (e.g. longer-lived and fewer eggs per clutch) increases the risk compared with similar birds living in colder regions when both experience the same environmental pollutant levels, then malaria control using DDT probably has more significant impacts on biota than previously realised. Therefore, risk assessment and modelling without hard data may miss crucial impacts and risks, as the chemical use patterns and ecologies in Africa and elsewhere may differ from the conditions and assumptions of existing risk assessment and modelling parameters. Consideration of other findings associated with DDT from the same area (intersex in fish and urogental birth defects in baby boys), together with the findings of this study (high levels of DDT in bird eggs, eggshell thinning in the Cattle Egrets, and the apparent absence of breeding piscivore birds in the sprayed area) are strongly suggestive of negative impacts from DDT spraying for Malaria control. Our data presents strong arguments for an expedited process of replacing DDT with sustainable methods. © 2013 Elsevier Inc. Source

de Vos J.,National Metrology Institute of South Africa | Dixon R.,South African Police Services Forensic Science Laboratory | Vermeulen G.,South African Police Services Forensic Science Laboratory | Gorst-Allman P.,LECO Africa Pty Ltd. | And 3 more authors.
Chemosphere | Year: 2011

The disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC × GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non-ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC × GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC × GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination. © 2010 Elsevier Ltd. Source

Nhlapo N.S.,University of Pretoria | Focke W.W.,University of Pretoria | Vuorinen E.,National Metrology Institute of South Africa
Thermochimica Acta | Year: 2012

Proprietary mixtures of amines and carboxylic acids are used as volatile corrosion inhibitors (VCIs) for the protection of iron and steel components against atmospheric corrosion. This study was focused on the nature of the vapors they release. VCI model compounds comprising mixtures of triethylamine and acetic acid were studied using thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR) at 50 °C. As vaporization progressed, the composition of the remaining liquid and the emitted vapor converged to a fixed amine content of ca. 27 mol%. This was just above the composition expected for the 1:3 amine to carboxylic acid complex. Mixtures close to this composition also featured the lowest volatility. © 2012 Elsevier B.V. All rights reserved. Source

Ramnath V.,National Metrology Institute of South Africa
International Journal of Metrology and Quality Engineering | Year: 2011

The behaviour of piston-cylinder operated pressure balances is characterized by the distortion coefficient λ and zero-pressure effective area A0 which model the variation of a pressure balance's area in terms of the applied pressure. This paper determines the uncertainties in λ and A0 when utilizing the method of cross-floating with another pressure balance standard whose parameters and associated uncertainties are known. A limitation that is frequently encountered in many attempts of the uncertainty analysis for a pressure balance is that no readily accessible uncertainty quantification framework for the distortion coefficient is present. As a result the uncertainty in a pressure balance's area at elevated applied pressures is typically underestimated in the absence of this uncertainty information. We firstly review the uncertainty formulation for a pressure balance generated pressure involving correlation effects in terms of an implicit multivariate matrix equation approach and then utilizing the resulting solution present the methodology to consistently perform the uncertainty analysis for λ and A0. © EDP Sciences 2012. Source

Azwar E.,KTH Royal Institute of Technology | Vuorinen E.,National Metrology Institute of South Africa | Hakkarainen M.,KTH Royal Institute of Technology
Polymer Degradation and Stability | Year: 2012

Pyrolysis-GC-MS of polylactide (PLA) biocomposites before and after hydrolytic degradation revealed prominent differences in the hydrolytic degradation process of rice bran and wood flour filled biocomposites. The water uptake and mass loss for polylactide/wood flour composites were similar to that of plain PLA. Pyrolysis-GC-MS, however, showed that on prolonged ageing the hydrolysis of PLA led to increased wood flour concentration in the remaining biocomposite matrices. In contrast, the polylactide/rice bran composites exhibited larger water uptake and higher mass loss. Pyrolysis-GC-MS and FTIR analysis proved that the higher mass loss was caused by migration of rice bran from the composites. The type of natural filler could thus greatly influence the degradation process and/or the stability of the materials in aqueous or humid environments. © 2011 Elsevier Ltd. All rights reserved. Source

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