EXPLORE CARDIFF UNIVERSITY
T.P. Jones, B.J. Williamson, K.A. BéruBé and R.J. Richards (2001) Atmospheric Environment. 35, (21), 3573-3583.
Tapered Element Oscillating Microbalances (TEOMs) are used in the UK Automatic Monitoring Network for the continuous measurement of ambient airborne particles. Used TEOM filters from Swansea, Cardiff and Pembroke were examined under high-resolution Field Emission Scanning Electron Microscopy (FESEM). Clusters of calcium sulphate crystals, gypsum (CaSO4.2H2O) and anhydrite (CaSO4) were abundant on Spring and Summer filters, and not present on Autumn and Winter filters. From textural considerations, the sulphates must have crystallised on the filter surfaces, either by dissolution and recrystallisation of CaSO4 collected as particles, or by direct precipitation from saline water collected on the filters; in much the same way as the formation of 'desert roses' by the evaporation of saline pore waters in desert sands. The proposed mechanism for the formation of these crystals has two important implications. Firstly, if the filters are episodically saturated with water, then on occasion the recorded masses will consist of both particles plus water, causing errors in the results of continuous monitoring; an important consideration for epidemiological studies based on TEOM data. Secondly, past toxicological experiments undertaken on TEOM-derived 'PM10' may have investigated material containing a significant component of in-situ formed crystals, rather than the original PM10.
FESEM of an assemblage of parallel fibrous gypsum (CaSO4.2H2O) crystals with a distinctive 'swallow-tail' morphology. Scale bar 2mm. FESEM of a radiating cluster of tabulate anhydrite (CaSO4) crystals. Scale bar 2 μm.
Comparison of the chemistry and toxicity of airborne dust and leachate generated by municipal landfills
Dr T. Jones (PI) and Prof. C. Harris (EARTH): Dr K. BeruBe (BIOSCI)
There are currently strong national and international concerns about the possible adverse health effects of living in the vicinity of municipal waste landfills (Review of Environmental and Health Effects of Waste Management: Municiple Solid Waste and Similar Wastes, DEFRA, May 2004). Despite alternatives such as incineration, re-cycling or re-use, approximately 80% of the UK's municipal waste goes to landfills. It is further estimated that 80% of the UK's population lives within 2 kilometres of a current or closed landfill: a surprisingly large percentage until the number of closed landfills within town and city areas are also included. Examples in Cardiff and Penarth of centrally located urban landfills include the closed Leckwith Moors, Penarth Marina, and Ferry Road sites. Current operating landfills include Lamby Way. The medical concerns surrounding landfills came from epidemiological studies and are focused on respiratory complaints, low and very low birth weights, spontaneous abortions, longer time to viable pregnancy, non-Hodgkins lymphoma, and incidence of sarcoidosis. In particular concerns are concentrated on congenital birth defects, including; neural tube defects, cardiovascular defects, hypospadias and epispadias, abdominal wall defects (ex. gastroschisis). Gastroschisis has been of particular concern at the Nant-y-Gwyddon landfill in south Wales. With the concerns based on inconclusive epidemiological data, an understanding of the ranges of toxicity of these landfill emissions is crucial to determine the degree of concern we should have about the potential effects they could have on nearby populations or the surrounding environment.
The plasmid assay was developed as a Reactive Oxygen Species (ROS) toxicity test system to be employed where controlled examination of multiple materials in animal experiments was impractical and/or unethical. Over the past years we have adapted a free radical assay whereby substances in very small quantities (5-10ug/ml) can split plasmid DNA by what is believed to be a free radical attack. The attack occurs at 3 levels; firstly small 'nicks' are made in the undamaged supercoiled DNA and result in the DNA uncoiling to a relaxed mode. The second level is when the nicks are sufficiently severe to linearise the DNA. The third stage is when the damage is so severe the DNA is reduced to a smear on the gel plate (Figure c). The damage to the DNA can then be semi-quantified to compare the toxicity of different samples. Since the results show percentage damage, they can be related to dosage (acute/chronic) exposure levels. The plasmid assay results have been used as a basis for later large-scale animal in-vivo experiments that have confirmed the use of the assay assay as a first-screening test to determine the bioreactivity of substances taken into the body.
A small pilot study was undertaken on landfill leachate (Figures a and b), collected by permission of the operators in a south Wales landfill. The purpose of the pilot study was to determine the suitability of our toxicological methods for landfill leachates, and to ascertain whether under our tests the leachate was toxic. When the leachate was collected the landfill site was actively accepting municipal waste, and the leachate will have formed with available oxygen present. The leachate was processed through a series of dilutions with distilled water, and tested in the plasmid assay. This system provides us with a useful primary toxicity assessment; and has potential for development for other pollution situations such as contaminated land . The results of the pilot study (Figures d and e) showed unequivocally the free radical activity of the landfill leachate. Pure leachate results in 100% loss of supercoiled DNA and smearing showing high DNA damage. The level of damage diminishes through the progressive dilutions, however at 100x dilution the damage is still approximately 8%. These analyses were run in duplicate with identical results. We conclude from these pilot results that the plasmid assay provides a relatively cheap and scientifically reliable and reproducible method for the assessment of landfill leachate toxicity. Furthermore it involves an applied holistic approach where the toxicity of the leachate is quantified as a 'cocktail' of numerous potentially harmful substances, instead of identifying individual components then predicting toxicity on the basis of existing literature. The advantages of this 'first screen' approach is that it permits an overview assessment of leachate toxicity that can consider numerous variables. These include the generation and migration of the leachate with the landfill, external climatic factors, and the chemical evolution of the landfills.
The respiratory toxicity of airborne volcanic ash from the Soufrière Hills volcano, Montserrat
BéruBé, K.A., Jones, T.P., Housley, G. H. and Richards, R.J. (2004). The Respiratory Toxicity of Airborne Volcanic Ash from the Soufriere Hills Volcano, Montserrat. Min. Mag. (in press)
Electron microscope image and size distribution (m ESD) histogram of volcanic ash from the Monserrat eruption.
The Soufrière Hills stratovolcano on the Caribbean island of Montserrat has been erupting since 18th July 1995. An enormous amount of respirable volcanic ash has been suspended into the atmosphere by the eruptions and wind re-suspension of deposited ash. The large amount of fine airborne particulate matter, in particular the component under 10μm equivalent aerodynamic diameter (PM10), is a cause of medical concern.
Electron microscope image and
These concerns have prompted government-funded investigations into the potential toxicity of well-characterized volcanic ash samples from Montserrat. Given the well-established toxicity of crystalline, particular attention was paid to the amount of this mineral in the ash samples. Comparative toxicological studies were carried out on respirable preparations of these three samples together with appropriate control mineral dusts that matched the major components of the Montserrat samples; anorthite, labradorite, cristobalite/obsidian, and cristobalite.
The data indicates that Montserrat respirable ash, derived from dome collapse pyroclastic flows or vulcanian explosions, has minimal acute bioreactivity in the lung. The feldspar standards showed low bioreactivity, in stark contrast to the cristobalite standard that showed progressive increases in lung damage. These results suggest that either the mass of cristobalite present in the Montserrat ash was insufficient to cause an effect in the lung, or the cristobalite in the ash was, for some as yet unknown reason, markedly less bioreactive than our pure cristobalite standard.
Particulate matter in the atmosphere
I am co-leader of the interdisciplinary Particles and Lung Research Group (PLRG) with Dr Kelly BéruBé in Biosciences, Cardiff. The PLRG won the IFSH Dietrich Hoffman Scientific Merit Award in 2006, and the NC3Rs Replacement prize 2007.
Lung and Particle Research Group Mobile Environmental Monitoring Unit
Laboratory fit-out: Interior lined with vetralite, floored with heavy-duty plastic coating. Work bench and cupboards. Mains power hook-up. It contains two fridges for sample storage and a roof-mounted air conditioning system. Roof rack and storage box for weather station. Rear door roof ladder and tow bar. Complete site PPE.
Skye Weather Station, with on-line 7-channel logger.On-line ambient gas analysers; CO, NO, NOx, O3DEKATI airborne particles impactor collector. Collects ambient airborne particles over the range PM10 to 7 nanometres in 10 separate collection plates. On-line particle size and number count.ASAP particle collector: sealed impaction system that is appropriate for bioaerosol collection.Laptop with DVD-writer
ROTAS luminescence toxicity system: organic, heavy metals, contaminated soil.LEICA QWin Imaging Workstation: Image AnalysisBench-top microcentrifugeSYSCAL resistivity system: ground geophysicsSoil leachate shaker: contaminated soil analysisGA2000 landfill gas analyserTrimble pathfinder GPSWAG Arsenator: field measurement of arsenic in groundwater4” borehole pump and control system
High-Volume collection systems
Stand-alone pumping system, running off 240V 13A, with a flow-rate of 1000 litres/minute. Tripod mounted R&P Chemvol 2400 impaction collector: TSP, 10-2.5μm, 2.5-0.1μm, HEPA base filter.Trailer mounted pumping system, running off 240V 13A, with a flow-rate of 1000 litres/minute. Roof-mounted R&P Chemvol 2400 impaction collector: TSP, 10-2.5μm, 2.5-0.1μm, HEPA base filter.
I have continuing interest in the causes and implications of a record of fossil charcoal since the Devonian. Current investigations include looking at material from the Triassic, Cretaceous and Tertiary. Work includes Electron probe X-ray analysis of particles (EPXMA) from wildfires and catastrophic events, in particular the K/T boundary.