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

This is the final report to the Department for Environment, Food & Rural Affairs (DEFRA) on the contract "Tributyltin (TBT) and the decline of the Norfolk Broads"

A global compilation of diatom silica oxygen isotope records from lake sediment - trends and implications for climate reconstruction

\ua9 Copyright: Oxygen isotopes in biogenic silica (δ18OBSi) from lake sediments allow for quantitative reconstruction of past hydroclimate and proxy-model comparison in terrestrial environments. The signals of individual records have been attributed to different factors, such as air temperature (Tair), atmospheric circulation patterns, hydrological changes, and lake evaporation. While every lake has its own local set of drivers of δ18O variability, here we explore the extent to which regional or even global signals emerge from a series of paleoenvironmental records. This study provides a comprehensive compilation and combined statistical evaluation of the existing lake sediment δ18OBSi records, largely missing in other summary publications (i.e. PAGES network). For this purpose, we have identified and compiled 71 down-core records published to date and complemented these datasets with additional lake basin parameters (e.g. lake water residence time and catchment size) to best characterize the signal properties. Records feature widely different temporal coverage and resolution, ranging from decadal-scale records covering the past 150 years to records with multi-millennial-scale resolution spanning glacial-interglacial cycles. The best coverage in number of records (NCombining double low line37) and data points (NCombining double low line2112) is available for Northern Hemispheric (NH) extratropical regions throughout the Holocene (roughly corresponding to Marine Isotope Stage 1; MIS 1). To address the different variabilities and temporal offsets, records were brought to a common temporal resolution by binning and subsequently filtered for hydrologically open lakes with lake water residence times <100 years. For mid- to high-latitude (>45\ub0N) lakes, we find common δ18OBSi patterns among the lake records during both the Holocene and Common Era (CE). These include maxima and minima corresponding to known climate episodes, such as the Holocene Thermal Maximum (HTM), Neoglacial Cooling, Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). These patterns are in line with long-term air temperature changes supported by previously published climate reconstructions from other archives, as well as Holocene summer insolation changes. In conclusion, oxygen isotope records from NH extratropical lake sediments feature a common climate signal at centennial (for CE) and millennial (for Holocene) timescales despite stemming from different lakes in different geographic locations and hence constitute a valuable proxy for past climate reconstructions

Palaeolimnological evidence for environmental change over the past millennium from Lake Qinghai sediments: a review and future research prospective

Lake Qinghai, on the NE Tibetan Plateau, is China's largest natural lake that lies at a triple junction of major climatic influences, making it sensitive to global climate change. As such, the sediments of Lake Qinghai have been the focus of numerous palaeoenvironmental studies spanning a range of timescales. However, as a result of uncertain age controls, uncertainties over interpretation of the proxies, the relative dearth of proxy calibration and lack of understanding of the modern lake system a coherent picture of climate over the NE Tibetan Plateau has yet to emerge from Lake Qinghai's sediment record. We review the state of knowledge for this important site, focusing on the last millennium. A comparison of the major proxy records show significant variability with a general pattern of change over the last 1000 years, notably those linked to the onset of the Little lee Age, but due to poor chronological constraints a detailed picture of climate change cannot be established. Further, some of the proxy records produced from Lake Qinghai's sediments are open to alternative explanations. This compounds the sediment record as a palaeoenvironmental archive. To fully realise the potential of Lake Qinghai, future research must concentrate on defining a reliable old carbon effect for the lake, calibrating proxy records with climatic processes and understanding spatial variability of proxy records within this large lake. (C) 2008 Elsevier Ltd and INQUA. All rights reserved

Alkenone-based reconstruction of late-Holocene surface temperature and salinity changes in Lake Qinghai, China

Few proxies can provide quantitative reconstructions of past continental climatic and hydrological changes. Here, we report the first alkenone-based reconstruction of late Holocene temperature and salinity changes in Lake Qinghai, China. The alkenone-temperature proxy (U37 k′) indicates up to a 1°C change in mean annual air temperature or a 2°C change in summer lake water temperature during the late Holocene. Oscillating warm and cold periods could be related to the 20th century warm period, the Little Ice Age, the Medieval Warm Period, the Dark Ages Cold Period, and the Roman Warm Period. The relative importance of C37:4 alkenone to total C37 alkenone production (%C37:4) fluctuated between 15-45%, with higher values during warm periods, suggesting that lake water was also fresher during these periods. The coupled late Holocene surface temperature and salinity changes suggest that Asian monsoons strongly influenced the climate of the Lake Qinghai region. Copyright 2006 by the American Geophysical Union.link_to_subscribed_fulltex