Speleothem and glacier records of latest Pleistocene–early Holocene climate change in the western North American interior

Rapid and high-magnitude North Atlantic climate oscillations following the Last Glacial Maximum have been correlated to climate change events in western North America. However, the strength of teleconnections between the North Atlantic and the interior of western North America remains poorly understood. We present a U-series calibrated speleothem record from Timpanogos Cave National Monument, located at 2040 m asl in the Wasatch Mountains of Utah, spanning 13.5–10.6 ka. Additionally, we carried out a climate reconstruction for a coeval glacier advance in the Wind River Range of Wyoming. Our results indicate that between 13.5 and 12.8 ka, the Wasatch was probably first cool and dry and then warmed. After 12.8 ka, our record suggests cool and/or wetter conditions followed by reduced moisture until 11.8 ka, followed by an early Holocene wet period. The Timpanogos record exhibits few similarities with those from the North Atlantic. Climate reconstructions of the Titcomb Basin glacier suggest modest temperature depressions relative to modern (<−3 °C) were necessary to sustain the glacier with a moderate increase in precipitation (>150%). The high-altitude speleothem record presented here provides a valuable basis for understanding latest Pleistocene–early Holocene glacial episodes in western North America.     

Land use,soil erosion,and sediment yield at Pinto Lake,California: comparison of a simplified USLE model with the lake sediment record

Quantitative interpretation of past land use using palaeolimnological records of sediment yield requires an appropriate soil erosion model. This paper describes the application of a simplified USLE model, comparing the predicted sediment yield with the lake sediment record at Pinto Lake (Central Coast, California). Our principal finding is that simplified USLE prediction, without correction for sediment transport capacity, accurately predicts fine sediment yield. Because the fine component of the soil is delivered far more efficiently than the coarse component, this and related soil erosion models can more readily be applied to the interpretation of palaeolimnological records than to estimation of total sediment yield, for which reliable estimation of hillslope and fluvial sediment storage are more important. The focus on fine sediment also means that the model output is optimal for assessing past ecological impacts of soil erosion on stream water turbidity and particulate transport of pollutants and nutrients.     

The Holme Pierrepont sand and gravel and the timing of Middle and Late Devensian floodplain aggradation in the English Midlands

This paper provides the first detailed, multi-proxy environmental record for the character of Lateglacial conditions in the lowest Pleistocene terrace of the main valley floor of the River Trent at Holme Pierrepont near Nottingham. The analysis of pollen, plant, insect and mollusc remains preserved within organic channels near the base of the terrace, named the Holme Pierrepont Sand and Gravel by the British Geological Survey (historically known as the Floodplain Terrace), provided evidence of cool, though not fully arctic climatic conditions and a largely treeless landscape, roamed by large herbivores. Radiocarbon dating indicates that these sediments were deposited during the Loch Lomond Stadial (Younger Dryas GS-1). Comparison of these dates from Holme Pierrepont with those from morphostratigraphically similar deposits in the wider Trent catchment suggests that the Holme Pierrepont Sand and Gravel may have been laid down in two separate pulses of braidplain aggradation either side of the ‘Last Glacial Maximum’. It has been demonstrated from historical documentation and riverine archaeological evidence that the middle Trent has been particularly sensitive to changing flood frequency and magnitude associated with climatic oscillations during the late Holocene; this study demonstrates that such sensitivity appears to extend back into the late Pleistocene. The timing of fluvial aggradation recorded at Holme Pierrepont agrees broadly with that recorded from other sites across England and north-west Europe.     

Protein‐like fluorescence intensity as a possible tool for determining river water quality

The results of a comparison between chemical water quality determinants and river water fluorescence on the River Tyne, NE England, demonstrate that tryptophan‐like fluorescence intensity shows statistically significant relationships between nitrate, phosphate, ammonia, biochemical oxygen demand (BOD) and dissolved oxygen. Tryptophan‐like fluorescence intensity at the 280 nm excitation/350 nm emission wavelength fluorescence centre correlates with both phosphate (r = 0·80) and nitrate (r = 0·87), whereas tryptophan‐like fluorescence intensity at the 220 nm excitation/350 nm emission wavelength centre correlates with BOD (r = 0·85), ammonia (r = 0·70) and dissolved oxygen (r = ?0·65). The strongest correlations are between tryptophan‐like fluorescence intensity and nitrate and phosphate, which in the Tyne catchment derive predominantly from point and diffuse source sewage inputs. The correlation between BOD and the tryptophan‐like fluorescence intensity suggests that this fluorescence centre is related to the bioavailable or labile dissolved organic matter pool. The weakest correlations are observed between tryptophan‐like fluorescence intensity and ammonia concentration and dissolved oxygen. The weaker correlation with ammonia is due to removal of the ammonia signal by wastewater treatment, and that with dissolved oxygen due to the natural aeration of the river such that this is not a good indicator of water quality. The observed correlations only hold true when treated sewage, sewerage overflows or cross connections, or agricultural organic pollutants dominate the water quality—this is not true for two sites where airport deicer (propylene glycol, which is non‐fluorescent) or landfill leachate (which contains high concentrations of humic and fulvic‐like fluorescent DOM) dominate the dissolved organic matter in the river. Mean annual tryptophan‐like fluorescence intensity agrees well with the General Water Quality Assessment as determined by the England and Wales environmental regulators, the Environment Agency. Copyright © 2004 John Wiley & Sons, Ltd.     

A novel methodology for identifying environmental exposures using GPS data

Aim: While studies using global positioning systems (GPS) have the potential to refine measures of exposure to the neighbourhood environment in health research, one limitation is that they do not typically identify time spent undertaking journeys in motorised vehicles when contact with the environment is reduced. This paper presents and tests a novel methodology to explore the impact of this concern.

Methods: Using a case study of exposure assessment to food environments, an unsupervised computational algorithm is employed in order to infer two travel modes: motorised and non-motorised, on the basis of which trips were extracted. Additional criteria are imposed in order to improve robustness of the algorithm.

Results: After removing noise in the GPS data and motorised vehicle journeys, 82.43% of the initial GPS points remained. In addition, after comparing a sub-sample of trips classified visually of motorised, non-motorised and mixed mode trips with the algorithm classifications, it was found that there was an agreement of 88%. The measures of exposure to the food environment calculated before and after algorithm classification were strongly correlated.

Conclusion: Identifying non-motorised exposures to the food environment makes little difference to exposure estimates in urban children but might be important for adults or rural populations who spend more time in motorised vehicles.