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Despite the extensive geographical range of palaeolimnological studies designed to assess the extent of surface water acidification in the United Kingdom during the 1980s, little attention was paid to the status of surface waters in the North York Moors (NYM). In this paper, we present sediment core data from a moorland pool in the NYM that provide a record of air pollution contamination and surface water acidification. The 41-cm-long core was divided into three lithostratigraphic units. The lower two comprise peaty soils and peats, respectively, that date to between approximately 8080 and 6740 cal. BP. The uppermost unit comprises peaty lake muds dating from between approximately ad 1790 and the present day (ad 2006). The lower two units contain pollen dominated by forest taxa, whereas the uppermost unit contains pollen indicative of open landscape conditions similar to those of the present. Heavy metal, spheroidal carbonaceous particle, mineral magnetics and stable isotope analysis of the upper sediments show clear evidence of contamination by air pollutants derived from fossil-fuel combustion over the last c. 150 years, and diatom analysis indicates that the naturally acidic pool became more acidic during the 20th century. We conclude that the exceptionally acidic surface waters of the pool at present (pH = c. 4.1) are the result of a long history of air pollution and not because of naturally acidic local conditions. We argue that the highly acidic surface waters elsewhere in the NYM are similarly acidified and that the lack of evidence of significant recovery from acidification, despite major reductions in the emissions of acidic gases that have taken place over the last c. 30 years, indicates the continuing influence of pollutant sulphur stored in catchment peats, a legacy of over 150 years of acid deposition. [ABSTRACT FROM AUTHOR]

A comprehensive and integrative view of East Asian monsoon evolution during the Holocene is still under debate, and additional high-resolution proxy records from climatically sensitive locations are requisite to solve this complex issue. In this paper, we present three well-dated mud/peat cores from a paleo-pingo depression in the Sanjiang Plain, a climatically sensitive region to monsoon variation, to reveal the paleoenvironmental history of the wetland and discuss the regional impacts from monsoon evolution. A paleolake developed in the study area before 5.5 ka BP, and a peatland initiated thereafter consequent upon the gradual shrinking of the paleolake. This transition lasted until 4.5 ka BP, when the paleolake changed entirely to a wetland. Considering the prevalent monsoon climate in the Sanjiang Plain, we suggest that the lake-to-wetland transition from 5.5 to 4.5 ka BP indicates a rapid decline of the East Asian summer monsoon in addition to autogenic basin infilling processes. Such a remarkable monsoon weakening event has been documented across northern China, and we associate this with ocean–atmosphere interactions throughout low-latitude regions. [ABSTRACT FROM AUTHOR]

Peat deposits from wetlands in the Upper Zambezi Valley provide an important long-term window on ecosystem dynamics in the Kalahari basin during the late Holocene. We use fossil pollen and macro-charcoal extracted from peat cores contained in three wetland sites to examine the response of vegetation to regional climate change. We find that during the last 6 ka, internal ecosystem dynamics are more important than climate, as observed by independent records, in determining vegetation assemblage change. Fire was found to be a persistent and important component of this savanna landscape for the duration of the ecological record, but biomass burning has increased markedly over the last 1000 years. The vegetation of the Upper Zambezi Valley appears to have a larger grassland component in the last few hundred years suggesting a more open landscape today than at any other time in the last 6000 years. [ABSTRACT FROM AUTHOR]

We set out to test the ability to detect vegetation change from organic soil nutrient (carbon and nitrogen) composition in the fire-determined forest/non-forest mosaic of western Tasmania, Australia. We find no relationship between organic soil nitrogen and carbon content, despite widely varying local vegetation and fire regimes. Pollen evidence supports the role of fire in driving an initial vegetation state change from forest to non-forest, while carbon and nitrogen analysis of the peat section suggest that factors other than peat nutrient (carbon and nitrogen) content are responsible for the observed meta-stability of non-forest at the site for 7000 years. We find that we cannot validate the use of organic soil nitrogen and carbon content for inferring vegetation type and question the degree of post-European vegetation change inferred from this method. [ABSTRACT FROM AUTHOR]

We present a multi-proxy paleoenvironmental study on a 10,400 cal. yr peat sequence from an ombrotrophic bog in coastal British Columbia, Canada. Pollen, non-pollen palynomorph, plant macrofossil, and physicochemical analyses (bulk density, %C, %N, δ13C, and δ15N isotopes) were used to document changes in vegetation, bog development, and carbon and nitrogen accumulation. Pollen assemblages indicate that regional vegetation in the warm, relatively dry early Holocene was mixed coniferous forest with scattered Pseudotsuga menziesii. Herbaceous peat with a C:N of ~28, combined with Nuphar microfossils and relatively high %N, suggests the presence of a herb-dominated peatland with standing water and/or bog pools. Carbon and nitrogen accumulation were at their highest during this early Holocene period at mean rates of 30.6 and 1.2 g/m2/cal. yr, respectively. By 8000 cal. yr BP and under a cooler, wetter climate, northern Vancouver Island supported Tsuga heterophylla rainforest similar to today. Decreasing relative water table, inferred from testate amoebae and fungal remains, facilitated the establishment of a Sphagnum bog by 8000 cal. yr BP with abundant ericaceous shrubs after 5000 cal. yr BP. Temporal variation in carbon accumulation rates corresponds with changes in plant functional types and hydrological conditions: rates were lowest in the early to mid-Holocene during accumulation of Sphagnum peat (7.1 g/m2/cal. yr) and increased in late Holocene ligneous peat (12.4 g/m2/cal. yr). Our multi-proxy approach not only demonstrates the overarching control of climate on bog development and carbon and nitrogen accumulation, with seasonality likely playing a major role, but also highlights the strong influence of autogenic processes at a local scale. [ABSTRACT FROM AUTHOR]

Interest in identifying a geological marker signifying the starting point for the Anthropocene has prompted an exploration of the stratigraphic record of inorganic particulates generated by industrial activities. Magnetic measurements of recent lake sediments and ombrotrophic peats are here used to reconstruct the history of deposition of inorganic fly-ash spheres resulting mainly from solid fuel combustion and metal smelting. The chronologies used have been based on moss-increment counting, radioisotope dating and pollen analysis. The sites come from the United Kingdom, Scandinavia and North America. In several cases where detailed chronologies of both fly-ash deposition and local industry can be compared, the sequence of concentration-linked magnetic measurements appears to capture accurately the record of industrial development despite incontrovertible evidence from other peat-based records for some selective dissolution of magnetic minerals. The dates at which magnetic concentration increases begin range from the 16th century in the peat profiles around the head of Morecambe Bay, South Cumbria, in North-West England where early iron manufacture using charcoal-fuelled bloomery hearths is well documented, to the mid-20th century at the remotest sites in Arctic Scandinavia. The lake sediment profiles used here come mainly from the United Kingdom and, in most cases, they date increases to the late 19th century or the first decades of the 20th century. Any attempt to use the magnetic record of fly-ash deposition in lake sediments and/or peats to mark the date chosen as the onset of the Anthropocene would require careful choice of site location and archive, bearing in mind the issue of selective magnetic mineral dissolution. [ABSTRACT FROM AUTHOR]

This study presents a new 3600-year record of past metal contamination from a bog located close to the Leadhills and Wanlockhead orefield of southwest Scotland. A peat core, collected from Toddle Moss, was radiocarbon (14C) dated and analysed for trace metal concentrations (by EMMA) and lead isotopes (by ICP-MS) to reconstruct the atmospheric deposition history of trace metal contamination, in particular, lead. The results show good agreement with documented historical and archaeological records of mining and metallurgy in the region: the peak in metal mining during the 18th century, the decline of lead mining during the Anglo-Scottish war and lead smelting during the early medieval period. There may also have been earlier workings during the Late Bronze and Iron Ages indicated by slight increases in lead concentrations, the Pb/Ti ratio and a shift in 206Pb/207Pb ratios, which compare favourably to the signatures of a galena ore from Leadhills and Wanlockhead. In contrast to other records across Europe, no sizeable lead enrichment was recorded during the Roman Iron Age, suggesting that the orefield was not a significant part of the Roman lead extraction industry in Britain. These findings add to the various strands of archaeological evidence that hint at an early lead extraction and metallurgical industry based in southern Scotland. The results also provide further evidence for specific regional variations in the evolution of mining and metallurgy and an associated contamination signal during prehistoric and Roman times across Europe. [ABSTRACT FROM AUTHOR]

To date, Holocene palaeoecological signatures on the Northwestern coast of France have not been thoroughly investigated. In this study, environmental changes related to both climate processes and human disturbances were reconstructed over the last 7000 cal. yr BP, based on pollen and chironomid assemblages from four coastal cores retrieved in Western Brittany (Porsmilin beach, NW France). Pollen and chironomid records show an environmental response to both millennial- and centennial-scale climate changes. During the mid-Holocene (until around 4200 cal. yr BP), when human impact was low, Porsmilin’s landscape was characterized by a mixed oak forest dominated by Corylus trees. Comparison of our data with other palynological data from the NW French Atlantic coast shows that this dominance may be related to more humid conditions prevailing at Porsmilin. Furthermore, over the mid-Holocene, Corylus and Quercus patterns appear anti-correlated, with Quercus declines appearing synchronous with major storms revealed by data recently compiled for the Holocene in Brittany, suggesting that cold conditions probably caused the Quercus contractions, which in turn favoured the rise of the heliophile taxon Corylus. Regarding chironomids over this period, our results show variations in lotic–lentic taxa related to hydrological conditions, more specifically changes in river run off strength. Over the Late Holocene, the Porsmilin palynological record shows progressive vegetation changes mainly related to human settlement and development of agricultural activities. [ABSTRACT FROM AUTHOR]

The nature and cause of the so-called 2.8 kyr BP event have been a subject of much debate. Peat sequences have provided much of the evidence for this event, but the process link between climate and peatland response is not well understood. Multiproxy, high-resolution analysis of a core from Bargerveen in the eastern Netherlands based on pollen, non-pollen palynomorphs, testate amoebae and geochemistry identified an abrupt shift from relatively dry to extremely wet conditions. Radiocarbon-based wiggle-match dating (WMD) and biostratigraphy based on the pollen record show that this shift in local hydrology occurred around 2800 cal. yr BP. We interpret an erosional hiatus lasting up to 950 years immediately prior to this, as the effect of a bog burst after excessive rainfall. This phenomenon was not limited to our sampling location but occurred over a large part of the former Bargerveen. Peat at the hiatus contains microfossils that reflect temporary eutrophication as a consequence of local fires and secondary decomposition because of increased drainage after the erosion event. Our data show how detailed multiproxy analyses can elucidate the past response of peatlands to changing climate and suggest that the climatic change in northwest Europe at this time caused major non-linear disruption to these ecosystems. [ABSTRACT FROM PUBLISHER]