Mercury in soil and stream water of selected catchments within the Czech Republic

Tomáš Navrátil1, Jan Rohovec1, Pavel Krám2, James Shanley3, Miroslav Tesař4, Šárka Matoušková1
1 Institute of Geology AS CR, v.v.i.
2 Czech Geological Survey
3 US Geological Survey
4 Institute of Hydrodynamics AS CR, v.v.i.

O 8.2 in Trace element and metal biogeochemistry

14.07.2014, 11:35-11:55, H20

The Czech Republic (CR) has been known for intensive coal mining and combustion in 1970s and 1980s, which resulted in extreme levels of acid deposition. The information on mercury (Hg) emissions from this period of time is missing but from archives such as soil and peat we know that Hg deposition was high. Further sources of Hg emissions within the CR have been metal industry, cement production and chlor-alkali production. Studies evaluating the fate of Hg deposited to the vulnerable ecosystems such as the forests are missing. An important question is how the level of Hg output varies at the sites with different impact of deposition. To answer this question we monitored soil Hg and stream water Hg output at 5 catchments within the CR with monthly step.

Five catchments (JEZ, LES, LIZ, LYS and PLB) disseminated over the area of the CR belong to the monitoring network GEOMON and are located in relatively rural conditions. Catchment LIZ is located in the Bohemian Forest, which represents the area with the least historical deposition. Sites JEZ, LYS and PLB are located within the area known as The Black Triangle, whereas the site JEZ belongs to the sites exposed to the most extreme acid deposition.

The site specific means of O horizon Hg concentrations ranged from 277 to 393 µg/kg, while means of Hg concentrations in mineral soil ranged from 22 to 100 ug/kg. Site specific mineral soil Hg pools (16-130 mg/m) dominated over organic soil Hg pools (5.3-10.1 mg/m2) at all sites. The cross site variability of Hg soil pools was not sensitive to the local Hg deposition history but rather related to the capacity of soil to store and stabilize organic matter (Navratil et al. 2014).

We compared the concentrations of Hg in streams at individual sites during hydrological years 2012 and 2013. The lowest median Hg concentration 1.3 ng/L was found at the least impacted site LIZ. Median Hg concentrations at sites JEZ, LES and LYS were 2.3, 2.5 and 5.3 ng/L. The highest median concentration of Hg was found at site PLB 18.7 ng/L. Similar to Hg, the highest median concentrations of DOC 19.9 and 15.9 mg/L were found at sites PLB and LYS. The DOC concentrations at resting sites JEZ, LES and LIZ were lower at 3.1, 7.9 and 3.7 mg/L. The median concentration of stream water Hg at site LIZ was the lowest as expected from the known historical deposition record in peat but also with the lowest DOC stream water concentration. But the highest stream water Hg concentration was found at site PLB with the highest DOC concentration. The concentrations of Hg in stream waters at individual sites reflect the concentration of DOC at a particular site rather than the historical level of pollution. Similarly the level of Hg export has been related to the site specific export of DOC. The stream water output fluxes of Hg from selected sites varied from 0.08 to 8.39 ug/m2.

The research was supported by the project P210/11/1369 of the Czech Science Foundation.

Navratil et al. (2014) Distribution and Pools of Mercury in Czech Forest Soils, WASP.

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last modified 2014-06-19