Human activity was a major driver of the mid-Holocene vegetation change in southern Cumbria: Implications for the elm decline in the British Isles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The dramatic decline in elm (Ulmus) across a large swathe of north-west Europe in the mid-Holocene has been ascribed to a number of possible factors, including climate change, human activity and/or pathogens. A major limitation for identifying the underlying cause(s) has been the limited number of high-resolution records with robust geochronological frameworks. Here, we report a multiproxy study of an upland (Blea Tarn) and lowland (Urswick Tarn) landscape in southern Cumbria (British Isles) to reconstruct vegetation change across the elm decline in an area with a rich and well-dated archaeological record to disentangle different possible controls. Here we find a two-stage decline in Ulmus taking place between 6350–6150 and 6050–5850 cal a BP, with the second phase coinciding with an intensification of human activity. The scale of the decline and associated human impact is more abrupt in the upland landscape. We consider it likely that a combination of human impact and disease drove the Ulmus decline within southern Cumbria.This work was funded by a studentship for MJG from the University of Exeter and Sir John Fisher Foundation. Additional funding for 14C dating was from the Cumberland and Westmorland Antiquarian and Archaeological Society (Clare Fell Bursary to MJG), and the Australian Research Council (FL100100195)

Matrix and Tensor Factorization Methods for Toxicogenomic Modeling and Prediction

Peer reviewe

The chemical speciation of Fe(III) in freshwaters

Dialysis and chemical speciation modelling have been used to calculate activities of Fe3+ for a range of UK surface waters of varying chemistry (pH 4.3–8.0; dissolved organic carbon 1.7–40.3 mg l-1) at 283K. The resulting activities were regressed against pH to give the empirical model: log aFe3+ = 2.76(±0.53) – 2.63(±0.08)•pH Predicted Fe3+ activities are consistent with a solid–solution equilibrium with hydrous ferric oxide. However, the apparent solubility of the solid phase decreases as pH decreases, consistent with some previous studies on Fe(III) solubility in the laboratory. The empirical model was used to predict concentrations of Fe in dialysates and ultrafiltrates of globally distributed surface and soil/ground waters. The predictions were improved greatly by the incorporation of a temperature correction for aFe3+, consistent with the temperature–dependence of previously reported hydrous ferric oxide solubility. The empirical model, incorporating temperature effects, may be used to make generic predictions of the ratio of free and complexed Fe(III) to dissolved organic matter in freshwaters. Comparison of such ratios with observed Fe : dissolved organic matter ratios allows an assessment to be made of the amounts of Fe present as Fe(II) or colloidal Fe(III), where no separate measurements have been made

Increasing iron concentrations in UK upland waters

Iron distributions in rainfall, streams, soils and groundwaters are described for the Upper River Severn catchment of mid-Wales. Iron is mainly supplied from within-catchment sources with highest concentrations occurring under reducing conditions. Iron concentrations have doubled over the past 20 years (~5.0 μg yr−1 for the forest and ~3.7 μg yr−1 for the moorland). For the forested sites, the gradients are particularly high post-1993. UK rivers/lakes monitored by the UK Acid Waters Monitoring Network show similar increases. Generally, Fe correlates with dissolved organic carbon (DOC). The greatest rates of Fe increase coincide with those for DOC. Thermodynamic modelling using WHAM/Model VI indicates that Fe(III) is mainly in microparticulate form (probably oxyhydroxides) apart from under reducing conditions. It is proposed that Fe increases for surface waters are associated with increased microparticulate Fe(III) due to stabilisation against aggregation by binding of DOM to its surface. The results relate to acidification declines and deforestation leading to land disturbance and wetter conditions within the soil. There will be greater acidification reversal following tree harvesting due to lowering of atmospheric SOx scavenging and this may have resulted in the greater increase in Fe in the later years of the study