This dataset contains sulphur concentrations and isotopic values found in tree rings. Samples were collected from several sites in Italy and in the UK. In Italy, samples were collected within a 4km radius of the Ernesto Cave (NE Italian Alps) using 5 and 12 mm diameter increment borers. Standard dendroecological procedures were used to produce absolutely dated records and mean ring-width chronologies. Thirty individual trees were used to build a master chronology for sample cores collected from Abies alba (type of fir tree)). Of the collected cores, two trees (Abies 1, cambial age 160; and Abies 2, cambial age 90) underwent preliminary investigation for sulphur concentration and intra-cellular speciation as a background to developing a method for extracting sulphur isotopes from the same samples. In sampling the trees, no oils, polish wax or lubricant was used to reduce potential contamination from sulphurcontaining compounds. Wood powders were extracted by carefully drilling 5-year blocks of dated rings to yield a well-mixed, representative sample of approximately 40 mg for sulphur isotope analysis. On a sub-section of the conifer samples, a cold resin extraction was conducted using a 9:1 high purity (Aristar grade) acetone:water mixture for 48 h, followed by multiple washes with hot and cold deionised water to remove the potentially mobile resinous component and any surface bound mobile (soluble) sulphur. Samples were also collected in the UK from Beech, Oak, Sycamore and Ash trees at sites near Lancaster, Manchester and Grizedale. Then all samples were analysed by continuous-flow-isotope-ratio mass spectrometry using an Isoprime 100 mass spectrometer linked to an Elementar Pyrocube analyser at the University of Lancaster, Lancaster Environment Centre. The results are presented in this dataset.

Sulphur is an element which is fixed within the woody tissues during growth and can be used with certainty for environmental reconstruction. That sulphur should be the element which is fixed within the annual growth rings is fortuitous given its key role in modulating climate and fantastic potential as an environmental diagnostic tool. The injection of sulphur aerosol into the atmosphere is a key determinant of climate through backscattering and absorption of radiation, and has long been a concern for terrestrial ecology, causing widespread acidification of catchments upon deposition. Historical sulphur concentration and isotopic values obtained from tree cores in Italy and in the UK are presented, spanning the period 1840-2012. This work was funded by NERC (grant NE/H012257/1).