363 research outputs found
Sediment accumulation in the Broads. A report to the Broads Authority
Sediment accumulation rate data are described for 15 cores from 11 sites in the Norfolk
and Suffolk Broads. Sediment dating was determined using a combination of radiometric
({210}^Pb, {137}^Cs) and spheroidal carbonaceous particle techniques. These approaches were
combined to produce a ‘best available chronology’ for each site. However, at some sites
results were still poor and the resulting data must be treated with caution
Atmospheric acidification history of Loch Laidon: a comparison of pollution records from 1985 and 1995 sediment cores
Like many oligotrophic softwater lochs in Scotland, Loch Laidon has been acidified by
atmospheric pollution (Flower et al. 1988). The process started in the 19th century when
industrial emissions began to contribute acidity (as sulphur and nitrogen oxides), heavy
metals, fly ash and other trace contaminants in significant quantities to the atmosphere.
Acidification of many sensitive freshwater lochs typically proceeded throughout the 20th
century ( e.g. Battarbee et al. 1988a). However, as a result of industrial decline and
implementation of some source controls, UK total acid emissions declined by about a third
between the mid- l 970s and the mid-1980s (Irwin et al. 1990). This change has been linked
to small decreases in the measured acidities of some Scottish lochs during the late l 970s and
1980s (Harriman et al. 1996). Biological improvements over this period are less clear,
although diatom communities in two upland lochs in Galloway (Battarbee et al. 1988b, Allott
et al. 1992) do show minor floristic recoveries since ca. 1980.
The time-scale and extent of acidification of Loch Laidon was revealed by microfossil and
geochemical analysis of a radiometrically dated sediment core retrieved from the loch in 1985
(Flower et al. 1988). The most recent sediment in this core showed no evidence of any
significant recovery trend in loch water acidity. Similarly, sediment contamination by
spheroidal carbonaceous particles (SCPs), a fly ash component of high temperature fossil fuel
burning, showed an increasing trend to the sediment surface (1985). To test if any biologically
significant changes or any decline in atmospheric contamination (as defined by SCP analysis)
of the loch had occurred in the 10 years subsequent to the 1985 palaeo-survey, re-sampling
was carried out in 1995. This re-survey entailed collecting a sediment core from
approximately the same location as the 1985 core and analysing it in similar ways.
Changing pollutant deposition patterns and possible lag-effects in biological responses to the
late 1970s acid emission decline, makes examination of the sediment record of the intervening
10 years of particular interest. This report presents results of radiometric dating, diatom
analysis and SCP analysis of the 1995 sediment core. Using the time scale provided by
sediment dating, diatom analysis is used to reconstruct recent trends in water pH and SCP
analysis is used to identify recent trends in direct atmospheric contamination. By comparing
the 1995 results with those obtained from the earlier core (Flower et al. 1988), not only is the
post 1985 sediment record made available but also replicability of the methods for the pre-
1985 sediment sections is tested
Investigation of environmental change at the Bosherston Lakes, Pembrokeshire
This is the final report to the Countryside Council for Wales under contract FC 73-01-322: Investigation of recent environmental change at Bosherston Lakes, a series of connected shallow lakes in Pembrokeshire
Water quality investigation of Loweswater, Cumbria
This is the final report to the Environment Agency: Water Quality Investigation of Loweswater, Cumbria. The project employs palaeolimnological techniques to evaluate the extent of eutrophication at Loweswater
Tributyltin (TBT) and the decline of the Norfolk Broads: Hickling Broad and Barton Broad
This study furthers the work of Sayer et al (2001), in which a model was presented regarding the collapse of the plant-dominated state in the aquatic ecosystem of the Norfolk Broads, E. England. The boat antifouling biocide tributyltin (TBT) was implicated as a toxic switching mechanism from evidence gathered in a palaeolimnological study of Wroxham Broad
- …