Diatom analysis of River Thames foreshore deposits exposed during the excavation of a Roman waterfront site at Pudding Lane, London. Report for the Department of Urban Archaeology, Museum of London

Eighty-seven diatom taxa including marine, brackish, and freshwater forms were identified from foreshore sediments accumulated against pre-AD 100 quay structures exposed during the excavation of an early Roman waterfront site in the city of London. The spectra indicate that the Roman port was probably established close to the tidal head of the river

The acidification of Scottish Lochs and the deprivation of critical sulphur loads from palaeolimnological data

A decade ago very little was known about acid lochs in Scotland. The implicit assumption was that they were largely free from pollution. In recent years the position has changed and we now have large bodies of data on the chemistry and biology of upland lochs (Harriman et al. 1986, Maitland et al. 1987, Battarbee et al. 1988) and clear evidence for the recent acidification of many sensitive sites (Flower and Battarbee 1983, Battarbee et al. 1985, Flower et al. 1987, Battarbee et al. 1988)

Palaeoecological evidence for the timing and causes of lake acidification in Galloway, South West Scotland

During the contract period sediment cores from six lakes, three with non-afforested and three with partially afforested catchments, were analysed to enable lake water acidity (pH) to be reconstructed over approximately the past 200 years. The sites are all situated on granitic rocks in the Galloway Hills of S.W. Scotland. The results of diatom analysis show that five of the six lakes have become considerably more acid over this time period and that the acidification process is mainly independent of catchment afforestation effects. {210}^Pb dating of the sediment shows that there has been little change in sediment accumulation rates at sites with non-afforested catchments, but there has been significant increases in accumulation rate at afforested sites associated with erosion caused by pre-planting catchment ploughing. Pollen analysis indicates that no major vegetation change has occurred at the non-afforested sites whilst trace metal analysis of L. Enoch (not funded by this contract) shows elevated levels of Pb, Cu, and Zn 1n the upper, post 1800 sediments. It is concluded that acid precipitation is the most likely cause of acidification at these sites

Royal Society Water Acidification Project (SWAP) Palaeolimnology Programme

In September 1983 the Royal Society launched a 500000 GBP research programme funded jointly by the Central Electricity Generating Board and the National Coal Board to investigate mechanisms of surface water acidification in Norway, Sweden, and the United Kingdom. The Management Committee of the programme identified palaeolimnology as a key area of research and we were invited to submit an integrated proposal that was aimed not only at tracing acidification history at important sites but also at evaluating alternative hypotheses for lake acidification in each of the three countries. We were also encouraged to use as wide a range of techniques as possible. The programme approved by the Management Committee initially in June 1984 and finally in December 1984 is summarised in the following pages. A number of projects began on October 1st 1984 and all remaining projects are scheduled to begin on April 1st 1985. The programme will be completed by September 1988 when the final results will be presented at an open discussion meeting

Rural sanitation in the Lough Erne catchment. History and influence on phosphorus loadings

This paper traces historical changes in the disposal of sewage effluent from the non-sewered population of 3 sub-catchments or Lough Erne, Ne Ireland, and considers the importance of effluent from these areas as a source of phosphorus to the lake. A questionnaire survey approach is used and the data gathered are compared to the results of a similar survey of a small river catchment in Gloucestershire

Acid Lakes in the Galloway Uplands, South West Scotland: catchments, water quality and sediment characteristics

Reports of diminishing salmonid fisheries and increasing acidity of lakes and streams in S.W. Scotland have attributed the cause to low pH precipitation (Wright &Henriksen 1980) and afforestation effects (Harriman & Morrison 1982). In 1981 we initiated a project with CEGB funding to examine the history of lakewater acidity in both afforested and unafforested catchments in the Galloway uplands (see frontispiece). Analysis of diatom remains in lake sediments is used to reconstruct lake pH change over the past 150 years at each site. Sediment chronology is provided by lead-210 dating (Appleby & Oldfield 1978). Contemporary limnological data on water quality and diatom communities has been collected over an annual cycle (1981-82) to aid evaluation of the sedimentary data

Fly-ash particles in lake sediments: extraction and characterisation. Report to the CEGB

Fly-ash particles are produced by high temperature combustion of coal and oil. They are dispersed widely in the environment, despite the presence of electrostatic precipitators on coal-fired station chimneys

A review of liming as a technique for protecting salmonid fish populations in acidified surface waters

Liming is a common technique that has been used in many countries to raise the alkalinity of acidified surface waters and alleviate some of the damaging effects of acidification on salmonid fish populations. The most common liming substance used is calcite, a calcium carbonate compound that is relatively inexpensive, available in different particle sizes and dissolves relatively quickly. It can be applied directly to streams or lakes or it can be applied to catchment soils. When applied to catchment soils its effect can be long-lasting but it can cause significant damage to those catchment plant and animal communities that are naturally adapted to acidic conditions. When applied directly to surface waters its effect can be immediate but applications need to be continuous or frequently repeated to counter downstream dilution and loss. For streams the most effective method is to use an automatic doser controlled by pHmeasuring sensors upstream and downstream of the doser to enable the exact quantity of lime needed to be added to the water body. Although effective this is an expensive method and one that needs to be maintained continuously for several years until the critical load exceedance has been eliminated. An alternative or complementary method is partial catchment liming by targeting water sources and selected wetlands to minimise damage to catchment vegetation. Liming can be very effective in restoring and protecting salmonid fish populations, but if over-applied it can lead to unwanted increases in alkalinity and productivity that may produce symptoms of eutrophication and unwanted changes in the composition of plant and algal communities downstream