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Abstract. Reconstructions of dust flux have been used to produce valuable global records of changes in atmospheric circulation and aridity. These studies have highlighted the importance of atmospheric dust in marine and terrestrial biogeochemistry and nutrient cycling. By investigating a 10 800-year-long paleoclimate archive from the Eastern Carpathians (Romania) we present the first peat record of changing dust deposition over the Holocene for the CarpathianBalkan region. Using qualitative (X-ray fluorescence (XRF) core scanning) and quantitative inductively coupled plasma optical emission spectrometer(ICP-OES) measurements of lithogenic (K, Si, Ti) elements, we identify 10 periods of major dust deposition between 9500-9200, 8400-8100, 7720-7250, 6350-5950, 5450-5050, 4130-3770, 3450-2850, 2000-1450, 800-620, and 60 cal yr BP to present. In addition, we used testate amoeba assemblages preserved within the peat to infer local palaeohydroclimatic conditions. Our record highlights several discrepancies between eastern and western European dust depositional records and the impact of highly complex hydrological regimes in the Carpathian region. Since 6100 cal yr BP, we find that the geochemical indicators of dust flux have become uncoupled from the local hydrology. This coincides with the appearance of millennial-scale cycles in the dust input and changes in geochemical composition of dust. We suggest that this is indicative of a shift in dust provenance from local-regional (likely loess-related) to distal (Saharan) sources, which coincide with the end of the African Humid Period and the onset of Saharan desertification.

SignificanceA detailed record of historical lead (Pb) pollution from a peat bog in Serbia provides a unique view on the extent and timing of Balkan mining and metallurgy. Evidence of the earliest European environmental pollution is followed by large-scale and sustained increases in the amount of anthropogenically derived Pb after 600 BCE, through the Roman/Byzantine periods, and into the medieval period. Occasional evidence of drops in pollution output reflects the disruptive socioeconomic impact of periods of turmoil. Our data show a trend significantly different to records in western Europe, where Pb pollution decreases dramatically after the collapse of the Roman Empire. These results suggest metal-rich southeastern Europe should be considered a more major player in environmental metal pollution through time.

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The Late Ordovician (~459-444 million years ago) was characterised by global cooling, glaciation and severe mass extinction. These events may have been driven by increased delivery of the nutrient phosphorus (P) to the ocean, and associated increases in marine productivity, but it is not clear why this occurred in the two pulses identified in the geological record. We link both cooling phases, and the extinction, to volcanic eruptions through marine deposition of nutrient-rich ash and the weathering of terrestrially emplaced ash and lava. We then reconstruct the influence of Late Ordovician volcanic P delivery on the marine system by coupling an estimate of bioavailable phosphate supply (derived from a depletion and weathering model) to a global biogeochemical model. Our model compares volcanic ash P content in marine sediments before and after alteration to determine depletion factors, and we find good agreement with observed carbon isotope and reconstructed temperature shifts. Hence, massive volcanism can drive substantial global cooling on million-year timescales due to P delivery associated with long-term weathering of volcanic deposits, offsetting the transient warming of greenhouse gas emission associated with volcanic eruptions. Such longer-term cooling and potential for marine eutrophication may be important for other volcanism-driven global events. Main TextThe Late Ordovician mass extinction (LOME) occurred in two phases, and in terms of species loss was the second greatest extinction event in Earth's history [1][2][3] . The Late Ordovician is characterised by a number of carbon isotope excursions (CIEs), with two globallyrepresented, the Guttenburg (GICE) at ~454 Ma, and Hirnantian (HICE) at ~ 445 Ma 4 . The GICE coincides with global cooling, and the beginning of the HICE is associated with widespread glaciation, with the cooling periods generally implicated in instigating the LOME 1,[5][6][7] .The primary driver behind the CIEs and associated cooling is uncertain. One possibility is that the emergence of early nonvascular land plants amplified terrestrial weathering and increased the delivery of the key limiting nutrient phosphorus to the oceans 8 .Greater availability of phosphorus increases marine productivity and organic carbon burial, driving a reduction in atmospheric CO 2 and a positive excursion in carbonate δ 13 C (ref. 9 ).Other proposals include an increasing fraction of eukaryotic marine production strengthening the biological pump 10 , and increased tropical weathering resulting from orogenesis augmenting the supply of phosphorus to the oceans 11 .The concept that Late Ordovician cooling was driven by organic carbon burial is supported by observations 12 , but why this occurred in two distinct pulses during the GICE and HICE is unclear. This pulsing may have arisen from early plants colonising new terranes 8 , but there is little evidence for this, although poor fossil preservation cannot be ruled out 13 . Further, the pace of early plant evolution remains highly uncertain 13 and there i...