210 Pb, 137 Cs and 239 Pu determinations from recent ombrotrophic peat profiles from two sites, Lough Fea Bog, Co. Tyrone, N. Ireland and Bolton Fell Moss, Cumbria, England are reported and ...discussed. 137 Cs profiles reflect both active uptake by contemporary living plants and downward diffusion in the peat. They therefore appear to be of no chronological value. At least at Bolton Fell Moss, 210 Pb profiles appear to be affected by sub-lateral and therefore possibly downward mobility of unsupported 210 Pb in the peat. They appear to underestimate true age in at least one of the profiles analysed. The 210 Pb derived dates appear to come closest to conforming with independent estimates of age based on pollen-analytical evidence, in the more waterlogged microenvironments on the mire surface, though the full effects on the mobility of unsupported 210 Pb of regional climate, bog hydrology and peat compaction and humification remain to be evaluated. Comparison of 239 Pu and 210 Pb derived dates for near surface peat suggest that the clear sub-surface peak in the concentration of fall-out plutonium may pre-date the true 1963 level in the peat. /// Обсуждаются результаты определений 210 Pb, 137 Cs и 239 Pu из современных профилей омбротрофных болот в 2-х местообитаниях - Лаф Фее Бор (Тирон, Сев. Ирландия) и Болтон Фелл Мосс (Камбрия, Англия). Профили 137 Cs отражают активность его потребления развивающимися растениями и скорость диффузии вдоль болотного nпрофиля. Т.о., они не представляют хронологическоло значения. По крайней мере в Волтои Фелл Мосс, профили 210 Pb находятся под влиянием сублатеральной (и направленной по-видимому вниз) подвижности незакрепленного 210 Pb в болоте. Они дают заниженные данные о возрасте, по крайней мере одного из исследованных профилей. Данные по содержанию 210 Pb близко подтверждаются результатами независимых определений возраста пыльцевым анализом; в более переувлажненных микробнотопах на поверхности трясины, несмотря на большое влияние локального климата, на подвижность незакрепленного 210 Pb должны быть определены гидрология болота, уплотнение и гумификация трясины. Сравнение данных по 239 Pu и 210 Pb у поверхности болота показывают, что в поверхностном слое четки пик концентрации выпадающего Pu может предсказать фактический его уровень 1963 в бопоте.
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Palaeolimnological techniques including diatom analysis were used to examine the acidification and atmospheric contamination histories of four lakes in Scotland. Results from an afforested and a ...moorland (control) site in a region of high acid deposition are compared with results from two similar sites in an area receiving lower acid deposition levels. Results show that afforestation of a catchment in the higher acid deposition area has increased the rate of lake acidification. There is no evidence for acidification as a result of forest growth alone in the area of lower acid deposition.
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A palaeoecological comparison is made between geologically sensitive sites chosen from an area of low sulphur deposition (Lochan Dubh) and area of high sulphur deposition (Round Loch of Glenhead). ...Pre-industrial (pre-1800) acidities of the lakes were similar but the pH of the Round Loch of Glenhead has subsequently dropped by over 0.5 of a pH unit whereas the pH of Lochan Dubh has only decreased slightly. The record of atmospheric contamination confirms that the Round Loch of Glenhead is a more heavily polluted site than Lochan Dubh. The increased degree of lake acidification and higher levels of atmospheric contamination at the Round Loch of Glenhead are correlated with the greater sulphur deposition levels at this site.
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The diatom data used for reconstructing pH within the Surface Water Acidification Project (SWAP) came from several different laboratories. The laboratories used agreed nomenclature and standardized ...identifications by using quality control techniques. A diatom database (disco) stored and processed counts and site information.
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