Abstract. Speleothems provide paleoclimate information on multimillennial to decadal scales in the Holocene. However, seasonal or even monthly resolved records remain scarce. Such records require fast-growing stalagmites and a good understanding of the proxy system on very short timescales. The Proserpine stalagmite from the Han-sur-Less cave (Belgium) displays well-defined/clearly visible darker and lighter seasonal layers of 0.5 to 2 mm thickness per single layer, which allows a measuring resolution at a monthly scale. Through a regular cave monitoring, we acquired a good understanding of how δ 18 O and δ 13 C signals in modern calcite reflect climate variations on the seasonal scale. From December to June, outside temperatures are cold, inducing low cave air and water temperature, and bio-productivity in the soil is limited, leading to lower pCO 2 and higher δ 13 C values of the CO 2 in the cave air. From June to December, the measured factors display an opposite behavior.The absence of epikarst water recharge between May and October increases prior calcite precipitation (PCP) in the vadose zone, causing drip water to display increasing pH and δ 13 C values over the summer months. Water recharge of the epikarst in winter diminishes the effect of PCP and as a result the pH and δ 13 C of the drip water gradually decrease. The δ 18 O and δ 13 C signals of fresh calcite precipitated on glass slabs also vary seasonally and are both reflecting equilibrium conditions. Lowest δ 18 O values occur during the summer, when the δ 13 C values are high. The δ 18 O values of the calcite display seasonal variations due to changes in the cave air and water temperature. The δ 13 C values reflect the seasonal variation of the δ 13 C DIC of the drip water, which is affected by the intensity of PCP. This same anticorrelation of the δ 18 O versus the δ 13 C signals is seen in the monthly resolved speleothem record that covers the period between 1976 and 1985 AD. Dark layers display lower δ 18 O and higher δ 13 C values. The cave system varies seasonally in response to the activity of the vegetation cover and outside air temperature between a "summer mode" lasting from June to December and a "winter mode" from December to June. The low δ 18 O and high δ 13 C values of the darker speleothem layers indicate that they are formed during summer, while light layers are formed during winter. The darker the color of a layer, the more compact its calcite structure is, and the more negative its δ 18 O signal and the more positive its δ 13 C signal are. Darker layers deposited from summer drip water affected by PCP are suggested to contain lower Ca 2+ concentration. If indeed the calcite saturation represents the main factor driving the Proserpine growth rate, the dark layers should grow slower than the white layers.

The objective of our study was to determine the trace metal accumulation rates in the Misten bog, Hautes-Fagnes, Belgium, and assess these in relation to established histories of atmospheric emissions from anthropogenic sources. To address these aims we analyzed trace metals and metalloids (Pb, Cu, Ni, As, Sb, Cr, Co, V, Cd and Zn), as well as Pb isotopes, using XRF, Q-ICP-MS and MC-ICP-MS, respectively in two 40-cm peat sections, spanning the last 600 yr. The temporal increase of metal fluxes from the inception of the Industrial Revolution to the present varies by a factor of 5e50, with peak values found between AD 1930 and 1990. A cluster analysis combined with Pb isotopic composition allows the identification of the main sources of Pb and by inference of the other metals, which indicates that coal consumption and metallurgical activities were the predominant sources of pollution during the last 600 years.

This study reports the variation of tree-ring widths and annual variation of concentration of metals (Na, Mg, Fe, Ni, Cu, Zn, Pb) in pine growing nearby chemical factories. The conifers (Pinus silvestris L.) investigated in this study covered the time span from 1920s to 2010 AD. Tree-ring widths were measured, dated and rechecked using the COFECHA. Radial trace-element profiles were determined by Laser Ablation Inductively Coupled Plasma Mass Spectrometry. The combined usage of tree ring width and chemical composition of wood provides historic records of anthropogenic impact on the environment and allows identifying the behavior adaptation of trees to the pollution. Data of pine tree cores collected from the sites nearby chemical factories show increasing levels of pollution linked to the increasing of industrial activities in Poland and subsequent dust fallout around the site. This study evidences that tree rings can be used as archives of past environmental contamination.

Four sediment cores were collected in 2008 from the Misten ombrotrophic peat bog in the Northern part of the Hautes Fagnes Plateau in Belgium. Total mercury (Hg) concentrations were analyzed to investigate the intra-site variability in atmospheric Hg deposition over the past 1,500 years. Mercury concentrations in the four cores ranged from 16 to 1,100 μg kg(-1), with the maxima between 840 and 1,100 μg kg(-1). A chronological framework was established using radiometric (210)Pb and (14)C dating of two cores (M1 and M4). Pollen horizons from these two cores were correlated with data from two additional cores, providing a consistent dating framework between all the sites. There was good agreement between atmospheric Hg accumulation rates in the four cores over time based on precise age dating and pollen chronosequences. The average Hg accumulation rate before the influence of human activities (from 500 to 1,300 AD) was 1.8 ± 1 μg m(-2)y(-1) (2SD). Maximum Hg accumulation rates ranged from 90 to 200 μg m(-2)y(-1) between 1930 and 1980 AD. During the European-North American Industrial Revolution, the mean Hg accumulation rate exceeded the pre-Industrial values by a factor of 63. Based on comparisons with historical records of anthropogenic activities in Europe and Belgium, the predominant regional anthropogenic sources of Hg during and after the Industrial Revolution were coal burning and smelter Hg emissions. Mercury accumulation rates and chronologies in the Misten cores were consistent with those reported for other European peat records.

Dust deposition in southern Belgium is estimated from the geochemical signature of an ombrotrophic peatland. The Rare Earth Elements (REE) and lithogenic elements concentrations, as well as Nd isotopes, were determined by HR-ICP-MS and MC-ICP-MS respectively, in along a ~6 m peat section covering 5300 yr, from 30 BC to 5300 BC dated by the ¹⁴C method. Changes in REE concentration in the peat correlate with those of Ti, Al, Sc and Zr that are lithogenic conservative elements, suggesting that REE are immobile in the studied peat bogs and can be used as tracers of dust deposition. Peat humification and testate amoebae were used to evaluate hydroclimatic conditions. The range of dust deposition varied from 0.03 to 4.0 g m⁻² yr⁻¹. The highest dust fluxes were observed from 800 to 600 BC and from 3200 to 2800 BC and correspond to cold periods. The εNd values show a large variability of −5 to −13, identifying three major sources of dusts: local soils, distal volcanic and desert particles