Sizeable net export of base cations from a Carpathian flysch catchment indicates their geogenic origin while the 26Mg/24Mg, 44Ca/40Ca and 87Sr/86Sr isotope ratios in runoff are indistinguishable from atmospheric input

Nutrient imbalances may negatively affect the health status of forests exposed to multiple stress factors, including drought and bark beetle calamities. We studied the origin of base cations in runoff from a small Carpathian catchment underlain by base-poor flysch turbidites using magnesium (Mg), calcium (Ca) and strontium (Sr) isotope composition of 10 ecosystem compartments. Our objective was to constrain conclusions drawn from long-term hydrochemical monitoring of inputs and outputs. Annual export of Mg, Ca and Sr exceeds 5-to-15 times their atmospheric input. Mass budgets per se thus indicate sizeable net leaching of Mg, Ca and Sr from bedrock sandstones and claystones. Surprisingly, δ26Mg, δ44Ca and 87Sr/86Sr isotope ratios of runoff were practically identical to those of atmospheric deposition and soil water but significantly different from bedrock isotope ratios. We did not find any carbonates in the studied area as a hypothetical, easily dissolvable source of base cations whose isotope composition might corroborate the predominance of geogenic base cations in the runoff. Marine carbonates typically have lower δ26 Mg and 87Sr/86Sr ratios, and silicate sediments often have higher δ26Mg and 87Sr/86Sr ratios than runoff at the study site. Mixing of these two sources, if confirmed, could reconcile the flux and isotope data.

Spatial and temporal trends in δ66Zn and 206Pb/207Pb isotope ratios along a rural transect downwind from the Upper Silesian industrial area: Role of legacy vs. present-day pollution

Transect sampling is an under-exploited tool in isotope studies of atmospheric pollution. Few studies have combined Zn and Pb isotope ratios to investigate whether atmospheric pollution at a receptor site is dominated by a different anthropogenic source of each of these toxic elements. It has been also unclear whether pollution abatement strategies in Central Europe have already resulted in regionally well-mixed background isotope signature of atmospheric Zn and Pb. Zinc and lead isotope ratios were determined in snow collected along a rural transect downwind from the Upper Silesian industrial area (southern Poland). Spatial and temporal gradients in δ⁶⁶Zn and ²⁰⁶Pb/²⁰⁷Pb ratios at four sites were compared with those of ore and coal collected in eight Czech and Polish mining districts situated at distances of up to 500 km. Snow pollution was extremely high 8 km from Olkusz in 2011 (1670 μg Zn L^-1; 240 μg Pb L^-1), sharply decreased between 2011 and 2018, and remained low in 2019-2021. Snow pollution was lower at sites situated 28-68 km from Olkusz. Across study sites, mean δ⁶⁶Zn and ²⁰⁶Pb/²⁰⁷Pb ratios of snow were -0.13‰ and 1.155, respectively. With an increasing distance from Olkusz, the δ⁶⁶Zn values first increased and then decreased, while the ²⁰⁶Pb/²⁰⁷Pb ratios first decreased and then increased. The δ⁶⁶Zn values in snow plotted closer to those of Upper Silesian ores (-0.20‰) than to the δ⁶⁶Zn values of Upper Silesian stone coal (0.52‰), showing predominance of smelter-derived over power-plant derived Zn pollution. The ²⁰⁶Pb/²⁰⁷Pb ratios of Upper Silesian coal (1.171) and Upper Silesian ores (1.180) were higher compared to those of snow. A²⁰⁶Pb/²⁰⁷Pb vs.²⁰⁸Pb/²⁰⁷Pb plot identified legacy pollution from leaded gasoline as the low-radiogenic mixing end-member. Across the transect sites, only the last sampling campaign exhibited a high degree of isotope homogenization for both Zn and Pb.

Catchment Runoff in Industrial Areas Exports Legacy Pollutant Zinc from the Topsoil Rather than Geogenic Zn

In highly industrialized, densely populated parts of Central Europe, mobilization of legacy Zn pollution from forest ecosystems may negatively affect the quality of water resources. To test this hypothesis, we determined the ⁶⁶Zn/⁶⁴Zn isotope ratios of 15 Zn reservoirs and fluxes in an acidified, spruce die-back affected mountain-slope catchment in northern Czech Republic. The δ⁶⁶Zn values of precipitation, organic horizon, and runoff were statistically indistinguishable. In contrast, δ⁶⁶Zn values of bedrock orthogneiss and mineral soil were significantly different from δ⁶⁶Zn values of runoff. The magnitude of within-site Zn isotope fractionations appeared to be relatively small. Despite the large potential source of Zn in bedrock, runoff exported mostly young pollutant Zn that had been temporarily stored in the organic horizon. This conclusion was corroborated by comparing Zn input-output mass balances in the polluted northern catchment and in a relatively unpolluted catchment situated 250 km to the south. Seven-times higher Zn export via runoff at the northern site was controlled by a combination of 10-times higher atmospheric Zn input and five-times higher DOC leaching, compared to the southern site. In industrial areas, atmospherically deposited Zn is leached from headwater catchments in a direct analogy to leaching of highly toxic pollutant Pb.

Controls on δ26Mg variability in three Central European headwater catchments characterized by contrasting bedrock chemistry and contrasting inputs of atmospheric pollutants

Magnesium isotope ratios (²⁶Mg/²⁴Mg) can provide insights into the origin of Mg pools and fluxes in catchments where Mg sources have distinct isotope compositions, and the direction and magnitude of Mg isotope fractionations are known. Variability in Mg isotope compositions was investigated in three small, spruce-forested catchments in the Czech Republic (Central Europe) situated along an industrial pollution gradient. The following combinations of catchment characteristics were selected for the study: low-Mg bedrock + low Mg deposition (site LYS, underlain by leucogranite); high-Mg bedrock + low Mg deposition (site PLB, underlain by serpentinite), and low-Mg bedrock + high Mg deposition (site UDL, underlain by orthogneiss). UDL, affected by spruce die-back due to acid rain, was the only investigated site where dolomite was applied to mitigate forest decline. The δ²⁶Mg values of 10 catchment compartments were determined on pooled subsamples. At LYS, a wide range of δ²⁶Mg values was observed across the compartments, from -3.38 ‰ (bedrock) to -2.88 ‰ (soil), -1.48% (open-area precipitation), -1.34 ‰ (throughfall), -1.19 ‰ (soil water), -0.99 ‰ (xylem), -0.95 ‰ (needles), -0.82 ‰ (bark), -0.76 ‰ (fine roots), and -0.76 ‰ (runoff). The δ²⁶Mg values at UDL spanned 1.32 ‰ and were thus less variable, compared to LYS. Magnesium at PLB was isotopically relatively homogeneous. The δ²⁶Mg systematics was consistent with geogenic control of runoff Mg at PLB. Mainly atmospheric/biological control of runoff Mg was indicated at UDL, and possibly also at LYS. Our sites did not exhibit the combination of low-δ²⁶Mg runoff and high-δ²⁶Mg weathering products (secondary clay minerals) reported from several previously studied sites. Six years after the end of liming at UDL, Mg derived from dolomite was isotopically undetectable in runoff.

Retraction Statement: Comparison of nitrogen inputs and accumulation in 210 Pb-dated peat cores: Evidence for biological N2 -fixation in Central European peatlands despite decades of atmospheric N pollution

"Comparison of nitrogen inputs and accumulation in ²¹⁰ Pb-dated peat cores: Evidence for biological N₂ -fixation in Central European peatlands despite decades of atmospheric N pollution" https://doi.org/10.1111/gcb.14505, by Martin Novak, Melanie A. Vile, Jan Curik, Bohuslava Cejkova, Jiri Barta, Marketa Stepanova, Ivana Jackova, Frantisek Buzek, Leona Bohdalkova, Eva Prechova, Frantisek Veselovsky, Marie Adamova, Ivana Valkova and Arnost Komarek. The above article, first published online in Wiley Online Library (wileyonlinelibrary.com) in Global Change Biology, has been retracted by agreement between the authors, the journal Editor-in-Chief, Stephen P. Long, and John Wiley & Sons Ltd. Since publication of the above article, it was brought to the attention of the authors that the peat accretion rates violate reasonable ranges of peatland C/N/P stoichiometry, placing the quantitative conclusions of the article in serious error. The authors apologize for any inconvenience the publication of this work may have caused our readers. REFERENCE Novak, M., Vile, M. A., Cejkova, B., Barta, J., Stepanova, M., Jackova, I., Buzek, F., Bohdalkova, L., Prechova, E., Veselovsky, F., Adamova, M., Valkova, I., & Komarek, A. (2018). Comparison of nitrogen inputs and accumulation in ²¹⁰ Pb-dated peat cores: Evidence for biological N₂ -fixation in Central European peatlands despite decades of atmospheric N pollution. Global Change Biology.. https://doi.org/10.1111/gcb.14505.

Cu-Zn isotope constraints on the provenance of air pollution in Central Europe: Using soluble and insoluble particles in snow and rime

Copper (Cu) and zinc (Zn) isotope ratios can be used to fingerprint sources and dispersion pathways of pollutants in the environment. Little is known, however, about the potential of δ⁶⁵Cu and δ⁶⁶Zn values in liquid and solid forms of atmospheric deposition to distinguish between geogenic, industrial, local and remote sources of these potentially toxic base metals. Here we present Cu-Zn deposition fluxes at 10 mountain-top sites in the Czech Republic, a region affected by extremely high industrial emission rates 25 years ago. Additionally, we monitored isotope composition of Cu and Zn in vertical and horizontal atmospheric deposition at two sites. We compared δ⁶⁵Cu and δ⁶⁶Zn values in snow and rime, extracted by diluted HNO₃ and concentrated HF. Cu and Zn isotope signatures of industrial pollution sources were also determined. Cu and Zn deposition fluxes at all study sites were minute. The mean δ⁶⁵Cu value of atmospheric deposition (-0.07‰) was higher than the mean δ⁶⁵Cu value of pollution sources (-1.17‰). The variability in δ⁶⁵Cu values of atmospheric deposition was lower, compared to the pollution sources. The mean δ⁶⁶Zn value of atmospheric deposition (-0.09‰) was slightly higher than the mean δ⁶⁶Zn value of pollution sources (-0.23‰). The variability in δ⁶⁶Zn values of atmospheric deposition was indistinguishable from that of pollution sources. The largest isotope differences (0.35‰) were observed between the insoluble and soluble fractions of atmospheric deposition. These differences may result from different sources of Cu/Zn for each fraction. The difference in isotope composition of soluble and insoluble particles appears to be a promising tool for pollution provenance studies in Central Europe.

Atmospheric deposition of beryllium in Central Europe: comparison of soluble and insoluble fractions in rime and snow across a pollution gradient

Little is known about atmospheric input of beryllium (Be) into ecosystems, despite its highly toxic behavior. For three consecutive winters (2009-2011), we measured Be concentrations in horizontal deposition (rime) and vertical deposition (snow) at 10 remote mountain-top locations in the Czech Republic, Central Europe. Beryllium was determined both in filtered waters, and in HF digests of insoluble particles. Across the sites, soluble Be concentrations in rime were 7 times higher, compared to snow (6.1 vs. 0.9ng·L(-1)). Rime scavenged the pollution-rich lower segments of clouds. The lowest Be concentrations were detected in the soluble fraction of snow. Across the sites, 34% of total Be deposition occurred in the form of soluble (bioavailable) Be, the rest were insoluble particles. Beryllium fluxes decreased in the order: vertical dry deposition insoluble>vertical dry deposition soluble>horizontal deposition soluble>vertical wet deposition insoluble>vertical wet deposition soluble>horizontal deposition insoluble. The average contributions of these Be forms to total deposition were 56, 21, 8, 7, 5 and 3%, respectively. Sites in the northeast were more Be-polluted than the rest of the country with sources of pollution in industrial Silesia.

Increasing arsenic concentrations in runoff from 12 small forested catchments (Czech Republic, Central Europe): patterns and controls

The 40-year long period of heavy industrialization in Central Europe (1950-1990) was accompanied by burning of arsenic-rich lignite in thermal power plants, and accumulation of anthropogenic arsenic in forest soils. There are fears that retreating acidification may lead to arsenic mobilization into drinking water, caused by competitive ligand exchange. We present monthly arsenic concentrations in surface runoff from 12 headwater catchments in the Czech Republic for a period of 13 years (1996-2008). The studied area was characterized by a north-south gradient of decreasing pollution. Acidification, caused mainly by SOx and NOx emissions from power plants, has been retreating since 1987. Between 1996 and 2003, maximum arsenic concentrations in runoff did not change, and were < 1 ppb in the rural south and < 2 ppb in the industrial north. During the subsequent two years, 2004-2005, maximum arsenic concentrations in runoff increased, reaching 60% of the drinking water limit (10 ppb). Starting in 2006, maximum arsenic concentrations returned to lower values at most sites. We discuss three possible causes of the recent arsenic concentration maximum in runoff. We rule out retreating acidification and a pulse of high industrial emission rates as possible controls. The pH of runoff has not changed since 1996, and is still too low (<6.5) at most sites for an As-OH(-) ligand exchange to become significant. Elevated arsenic concentrations in runoff in 2004-2005 may reflect climate change through changing hydrological conditions at some, but not all sites. Dry conditions may result in elevated production of DOC and sulfur oxidation in the soil. Subsequent wet conditions may be accompanied by acidification leading to faster dissolution of arsenic-bearing sulfides, dissolution of arsenic-bearing Fe-oxyhydroxides, and elevated transport of arsenic sorbed on organic matter. Anaerobic domains exist in normally well-aerated upland soils for hours-to-days following precipitation events.