Neil L. Rose

DATING OF RECENT LAKE-SEDIMENTS IN THE UNITED-KINGDOM AND IRELAND USING SPHEROIDAL CARBONACEOUS PARTICLE (SCP) CONCENTRATION PROFILES

Spheroidal carbonaceous particles (SCPs) produced from fossil-fuel combustion are found in lake sediments and provide a historical record of atmospheric pollutant deposition. The sediment record of these particles is remarkably consistent and the main features are now seen throughout Europe and beyond. Once the SCP record from a region has been established using accurately dated cores, SCP profiles can be used to determine dates at other sites in the region. This technique was developed in Sweden but until recently has had limited use in the UK and Ireland as the most useful dating feature, the subsurface peak, was not present in all cores. In recent cores this can now almost always be observed. Dating features for UK and Irish cores are found to differ slightly between regions. The potential exists for extra dates to be allocated to a profile by using characterisation of SCP surfaces to determine changes in fuel-type use. Dates could then be allocated to these changes using documentary sources to derive combustion histories. In future years, SCP dating will become increasingly valuable especially for mid- to late-nineteenth-century sediments as continual decay renders210 Pb progressively less useful for this time interval.

Replicated proxy-climate signals over the last 2000 yr from two distant UK peat bogs: new evidence for regional palaeoclimate teleconnections

Ombrotrophic peat is an established source of proxy-climate data but previous records have been produced by different methods and have been difficult to compare. High-resolution plant macrofossil analysis has been applied to a lowland raised bog at Fallahogy, Northern Ireland, and a montane blanket bog, Moine Mhor in the Cairngorms, Scotland. Although the bogs are 300 km apart and differ floristically, the results demonstrate parallel responses to climatic forcing, especially that of the Little Ice Age. This approach provides a powerful tool for reconstructing proxy-climate records wherever suitable peat deposits exist. In contrast to the ocean and ice core records these proxies are from a terrestrial source, and related to climate changes on land over most of the Holocene.

A note on further refinements to a procedure for the extraction of carbonaceous fly-ash particles from sediments

This paper describes improvements to a previously published technique for the extraction of carbonaceous fly-ash particles from sediments. By using test-tubes in a water-bath rather than beakers on a hot-plate, the number of simultaneous preparations that can be done is increased and the length of time spent on the preparations and the amounts of hazardous chemicals used is reduced. As the digestion vessel remains the same throughout the procedure, potential loss of particles due to transfer of material between vessels is also minimised, whilst keeping sensitivity, accuracy and detection limit the same.

Looking forward through the past : identification of 50 priority research questions in palaeoecology

Summary 1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on timescales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. This article is protected by copyright. All rights reserved. Accepted Article 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation, and novel ecosystems; biodiversity over long timescales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes, and the continued application of long-term data for better-informed landscape management. 7. Synthesis Palaeoecology is a vibrant and thriving discipline and these 50 priority questions highlight its potential for addressing both pure (e.g. ecological and evolutionary, methodological) and applied (e.g. environmental and conservation) issues related to ecological science and global change.

A method for the extraction of carbonaceous particles from lake sediment

The methods found in the literature for the extraction of carbonaceous particles from lake sediment are discussed. The technique used by Griffin & Goldberg (1975) on Lake Michigan sediments was improved by modifying the procedure to halve the extraction time and reduce the risk of fragmentation. This method was then applied to a sediment core taken from Loch Tinker in Western Scotland, which had previously been analysed using the Renberg & Wik method. Although the basic trends for both methods are the same, the new method is found to be more sensitive to low particle numbers and more accurate, due to a more efficient extraction and a higher magnification for microscope counting.

Historical record of polycyclic aromatic hydrocarbons (PAHs) and spheroidal carbonaceous particles (SCPs) in marine sediment cores from Admiralty Bay, King George Island, Antarctica

This paper describes the first results of polycyclic aromatic hydrocarbons (PAHs) and spheroidal carbonaceous particles (SCPs) in sediment cores of Admiralty Bay, Antarctica. These markers were used to assess the local input of anthropogenic materials (particulate and organic compounds) as a result of the influence of human occupation in a sub-Antarctic region and a possible long-range atmospheric transport of combustion products from sources in South America. The highest SCPs and PAHs concentrations were observed during the last 30 years, when three research stations were built in the area and industrial activities in South America increased. The concentrations of SCPs and PAHs were much lower than those of other regions in the northern hemisphere and other reported data for the southern hemisphere. The PAH isomer ratios showed that the major sources of PAHs are fossil fuels/petroleum, biomass combustion and sewage contribution generally close to the Brazilian scientific station.

Sedimentary evidence for changes in the pollution status of Taihu in the Jiangsu region of eastern China

As part of a study using lake sediments to determine the extent and causes of human impacts to lakes along an east–west transect following the Yangtse River, sediment cores were taken from Taihu in eastern China. Previous studies have focussed on the impacts of direct inputs of pollutants from municipal and industrial wastewater but little work has been undertaken on trends in atmospheric deposition from the many industrial sources surrounding the lake. Analysis of the Taihu sediment cores for atmospheric pollutant indicators such as trace metals, magnetic parameters and spheroidal carbonaceous particles (SCPs) show the lake has become increasingly contaminated over the last 40–50 years. Sediment levels of atmospherically deposited pollutants are currently similar to some of the more contaminated lakes in Europe. Further, sediment nitrogen, phosphorus and geochemical analyses confirm the dramatic increase in eutrophication at the site and periods of recent soil erosion in the catchment.

Distribution of mercury in six lake sediment cores across the UK.

Six sediment cores, from Lochnagar, Loch Chon and Loch Grannoch in Scotland, Burnmoor Tarn in the English Lake District, Llyn Llagi in the Snowdonia region of Wales and Banbury Reservoir in London, were taken in order to study the distribution of Hg temporally and historically in lake sediments across the UK. These cores were dated using the spheroidal carbonaceous particle technique. The cores show that all sites across the UK have been contaminated by Hg. There is a rapid increase in Hg concentration during the last approximately 200 years at all rural sites. In the 95 year record from Banbury Reservoir in London the sediments show high Hg concentrations (380-840 ngg(-1)) throughout. Inter-site differences in Hg concentrations and profiles may be explained by impacts of afforestation, composition of the sediments and the provenance of the Hg including catchment in-wash influences. For example, catchment contributions result in a sharp peak (1606 ngg(-1)) in the Hg concentration profile in the core taken from Loch Chon in the Trossachs region of Scotland. Mercury fluxes were calculated for the sediment cores and show that over the last few decades these UK sites, except Lochnagar, would fall into the upper range for European rural areas.

Lake-sediment evidence for local and remote sources of atmospherically deposited pollutants on Svalbard

Twenty-one lakes along the west coast of Svalbard were cored between 28 July and 14 August 1995. Five cores were 210Pb dated and analysed for spheroidal carbonaceous particles (SCPs), indicators of deposition from fossil-fuel combustion sources, and trace metals. Surface and pre-industrial levels of five cores were analysed for 10 polychlorinated biphenyl (PCB) isomers and 16 polycyclic aromatic hydrocarbon (PAH) compounds, whilst all 21 surface sediments were analysed for SCPs. Temporal and spatial trends in the atmospheric deposition of pollutants were identified. Whilst temporal patterns of deposited pollutants may have been truncated due to concentrations falling below the limits of detection, spatial patterns showed elevated levels of SCP, PAH, PCB, and possibly Pb within 60–70 km of Isfjord. Tenndammen (U), the closest site to Longyearbyen, showed the highest levels of contamination for all pollutants. Differences in the deposition patterns of PAH and PCB are thought to be due to local sources of PAH from coal combustion whilst PCB sources are remote. It is concluded that the impact from atmospheric deposition on Svalbard is due to a combination of spatially limited local sources superimposed on a broad-scale, long-range pattern.

The historical record of PAH, PCB, trace metal and fly-ash particle deposition at a remote lake in north-west Scotland

Sediment cores taken from the deep basin of Loch Coire nan Arr in north-west Scotland were dated using 210Pb calibrated spheroidal carbonaceous particle (SCP) profiles and analysed for trace metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). These data show that the site is one of the least contaminated by atmospheric pollution in the UK. Peak concentrations of PAHs were found to be equivalent to background values at sites in the English Lake District. The date of concentration maxima for SCP, PCB and some metals were in agreement with previously published polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran (PCDD/F) data suggesting long-range industrial sources. The date of individual PAH concentration maxima were earlier, but concomitant with each other, possibly suggesting the influence of a local source. Comparison with remote European mountain lakes shows Loch Coire nan Arr to be one of the least contaminated sites in Europe with respect to PCBs, but more contaminated with respect to PAHs.