Geology topics

Filip Oulehle

Publications and source records attributed to Filip Oulehle.

4 recordsLinked to original sources

USGS2025

Mercury cycling in the Czech GEOMON network catchments recovering from acid deposition and facing climate change

We used the catchment mass balance approach to investigate mercury (Hg) cycling at the 14 forested GEOMON catchments of the Czech Geological Survey. The temperate forest catchments had variable exposure to historic high sulfur (S) and Hg emissions, and span a range of size and elevation. We monitored monthly Hg inputs (bulk precipitation, throughfall, litterfall) and outputs (stream runoff) during 2020–2022. The catchments spanned a large gradient of historic Hg deposition, but current Hg patterns more closely aligned with catchment factors like local climate, as influenced by elevation, dissolved organic carbon (DOC) concentrations, and geology. The dominant pathway of Hg input was litterfall (averaging 44.5 ± 15.7 µg m −2 yr −1 ; > 91% of total input). Two surprising findings were that GEOMON had low Hg concentrations and fluxes in general but had the highest litterfall Hg fluxes in Europe, and these increased even further in forested areas that had bark beetle infestations. Gaseous elemental mercury (GEM), measured using passive samplers, was consistently low (1.25 to 1.66 ng m −3 ) across the 14 catchments. Stream Hg output varied across catchments and averaged 1.5 ± 1.7 µg m −2 yr −1 . The average Hg retention rate at the 14 GEOMON catchments, calculated as the fraction of average Hg inputs (throughfall + litterfall) that remained in the catchment and did not run off in streamwater, was 97%. The high catchment Hg retention combined with its strong association with DOC suggests that with climate change intensification of carbon cycling, these catchments will be a Hg source for decades to come.

Biogeochemistry↗

USGS2021

Mercury cycling during acid rain recovery at the forested Lesní potok catchment, Czech Republic

From 2011 to 2019, mercury (Hg) stores and fluxes were studied in the small forested catchment Lesní potok (LES) in the central Czech Republic using the watershed mass balance approach together with internal measurements. Mean input fluxes of Hg via open bulk deposition, beech throughfall and spruce throughfall during the periodwere 2.9, 3.9 and 7.6 μg m −2 year −1 , respectively. These values were considerably lower than corresponding deposition Hg fluxes reported in the early years of the 21st century from catchments in Germany. Current bulk precipitation inputs at unimpacted Czech mountainous sites were lower than those in Germany. The largest Hg inputs to the catchment were via litterfall, averaging 22.6 and 17.8 μg m −2 year −1 for beech and spruce stands. The average Hg input, based on the sum of mean litterfall and throughfall deposition, was 23.0 μg m −2 year −1 , compared to the estimated Hg output in runoff of 0.5 μg m −2 year −1 , which is low compared to other reported values. Thus, only ~2% of Hg input is exported in stream runoff. Stream water Hg was only weakly related to dissolved organic carbon (DOC) but both concentrations were positively correlated with water temperature. The estimated total soil Hg pool averaged 47.5 mg m −2 , only 4% of which was in the O-horizon. Thus Hg in the O-horizon pool represents 72 years of deposition at the current input flux and 3800 years of export at the current runoff flux. Age-dating by 14 C suggested that organic soil contains Hg from recent deposition, while mineral soil at 40–80 cm depth contained 4400-year old carbon, suggesting the soil had accumulated atmospheric Hg inputs through millennia to reach the highest soil Hg pool of the soil profile. These findings suggest that industrial era intensification of the Hg cycle is superimposed on a slower-paced Hg cycle during most of the Holocene.

Lesní potok↗

USGS2016

Soil mercury distribution in adjacent coniferous and deciduous stands highly impacted by acid rain in the Ore Mountains, Czech Republic

Forests play a primary role in the cycling and storage of mercury (Hg) in terrestrial ecosystems. This study aimed to assess differences in Hg cycling and storage resulting from different vegetation at two adjacent forest stands - beech and spruce. The study site Načetín in the Czech Republic's Black Triangle received high atmospheric loadings of Hg from coal combustion in the second half of the 20th century as documented by peat accumulation rates reaching 100 μg m −2 y −1 . In 2004, the annual litterfall Hg flux was 22.5 μg m −2 y −1 in the beech stand and 14.5 μg m −2 y −1 in the spruce stand. Soil concentrations and pools of Hg had a strong positive relation to soil organic matter and concentrations of soil sulfur (S) and nitrogen (N). O-horizon Hg concentrations ranged from 245 to 495 μg kg −1 and were greater in the spruce stand soil, probably as a result of greater dry Hg deposition. Mineral soil Hg concentrations ranged from 51 to 163 μg kg −1 and were greater in the beech stand soil due to its greater capacity to store organic carbon (C). The Hg/C ratio increased with depth from 0.3 in the O-horizon to 3.8 μg g −1 in the C horizon of spruce soil and from 0.7 to 2.7 μg g −1 in beech soil. The Hg/C ratio was greater at all mineral soil depths in the spruce stand. The organic soil Hg pools in beech and spruce stands (6.4 and 5.7 mg m −2 , respectively) were considerably lower than corresponding mineral soil Hg pools (39.1 and 25.8 mg m −2 ). Despite the important role of S in Hg cycling, differences in soil Hg distribution at both stands could not be attributed to differences in soil sulfur speciation.

Ore Mountains↗

USGS2015

Mercury in stream water at five Czech catchments across a Hg and S deposition gradient

The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0 ng L − 1 . The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3 μg m − 2 yr − 1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90 ng mg − 1 . The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories.

Journal of Geochemical Exploration↗