Mercury in the Idrijca River sediments as a reflection of mining and smelting activities of the Idrija mercury mine

doi:10.1016/S0375-6742(96)00064-7

Journal of Geochemical Exploration

Volume 58, Issues 2–3, April 1997, Pages 125-131

https://doi.org/10.1016/S0375-6742(96)00064-7 Get rights and content

Abstract

Stream and flood plain sediments along the valley of the Idrijca River were systematically sampled. Upstream of the mercury mining town of Idrija, the Hg in stream sediment varies around 2 mg/kg. Mecury contents in the region from Idrija downstream to the town of Spodnja Idrija are from 100 to 1, 000 mg/kg. Downstream from Spodnja Idrija, sediments contain lower Hg (from 5 to 300 mg/kg). Recent overbank sediments are enriched relative to the stream sediments downstream of Idrija. River flood plain sediments that represent an accumulation of polluted sediments have Hg contents of 100 to 200 mg/kg.

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Dissolved gaseous mercury production and sea-air gaseous exchange in impacted coastal environments of the northern Adriatic Sea
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The northern Adriatic Sea is well known for mercury (Hg) contamination mainly due to historical Hg mining which took place in Idrija (Slovenia). The formation of dissolved gaseous mercury (DGM) and its subsequent volatilisation can reduce the amount of Hg available in the water column. In this work, the diurnal patterns of both DGM production and gaseous elemental Hg (Hg⁰) fluxes at the water-air interface were seasonally evaluated in two selected environments within this area, a highly Hg-impacted, confined fish farm (VN: Val Noghera, Italy) and an open coastal zone less impacted by Hg inputs (PR: Bay of Piran, Slovenia). A floating flux chamber coupled with a real-time Hg⁰ analyser was used for flux estimation in parallel with DGM concentrations determination through in-field incubations. Substantial DGM production was observed at VN (range = 126.0–711.3 pg L⁻¹) driven by both strong photoreduction and possibly dark biotic reduction, resulting in higher values in spring and summer and comparable concentrations throughout both day and night. Significantly lower DGM was observed at PR (range = 21.8–183.4 pg L⁻¹). Surprisingly, comparable Hg⁰ fluxes were found at the two sites (range VN = 7.43–41.17 ng m⁻² h⁻¹, PR = 0–81.49 ng m⁻² h⁻¹), likely due to enhanced gaseous exchanges at PR thanks to high water turbulence and to the strong limitation of evasion at VN by water stagnation and expected high DGM oxidation in saltwater. Slight differences between the temporal variation of DGM and fluxes indicate that Hg evasion is more controlled by factors such as water temperature and mixing conditions than DGM concentrations alone. The relative low Hg losses through volatilisation at VN (2.4–4.6% of total Hg) further confirm that static conditions in saltwater environments negatively affect the ability of this process in reducing the amount of Hg retained in the water column, therefore potentially leading to a greater availability for methylation and trophic transfer.
Gaseous mercury evasion from bare and grass-covered soils contaminated by mining and ore roasting (Isonzo River alluvial plain, Northeastern Italy)
2023, Environmental Pollution
High amounts of mercury (Hg) can be released into the atmosphere from soil surfaces of legacy contaminated areas as gaseous elemental mercury (Hg⁰). The alluvial plain of the Isonzo River (NE Italy) suffered widespread Hg contamination due to the re-distribution of Hg-enriched material discharged by historical cinnabar mining at the Idrija mine (Slovenia), but an assessment of Hg⁰ releases from the soils of this area is still lacking. In this work, Hg⁰ fluxes at the soil-air interface were evaluated using a non-steady state flux chamber coupled with a real-time Hg⁰ analyser at 6 sites within the Isonzo River plain. Measurements were performed in summer, autumn, and winter both on bare and grass-covered soil plots at regular time intervals during the diurnal period. Moreover, topsoils were analysed for organic matter content and Hg total concentration and speciation. Overall, Hg⁰ fluxes tracked the incident UV radiation during the sampling periods with daily averages significantly higher in summer (62.4 ± 14.5–800.2 ± 178.8 ng m⁻² h⁻¹) than autumn (15.2 ± 4.7–280.8 ± 75.6 ng m⁻² h⁻¹) and winter (16.9 ± 7.9–187.8 ± 62.7 ng m⁻² h⁻¹) due to higher irradiation and temperature, which favoured Hg reduction reactions. In summer and autumn significant correlations were observed between Hg⁰ fluxes and soil Hg content (78–95% cinnabar), whereas this relationship was not observed in winter likely due to relatively low emissions found in morning measurements in all sites coupled with low temperatures. Finally, vegetation cover effectively reduced Hg⁰ releases in summer (∼9–68%) and autumn (∼41–78%), whereas the difference between fluxes from vegetated and bare soils was not evident during winter dormancy due to scarce soil shading. These results suggest the opportunity of more extended spatial monitoring of Hg⁰ fluxes particularly in the croplands covering most of the Isonzo River alluvial plain and where bare soils are frequently disturbed by agricultural practices and directly exposed to radiation.
Occupational exposure to mercury from cinnabar enriched sand in workers of Grado Beach, Gulf of Trieste (North-eastern Italy, upper Adriatic Sea)
2022, Marine Pollution Bulletin
Health and safety of occupations entailing extensive skin contact with cinnabar-enriched sand in beaches of Friuli-Venezia Giulia (FVG) Region (North-eastern Italy) have been questioned for possible skin absorption of mercury (Hg). One hundred mg hair was collected from the occipital scalp of 50 male workers of Grado beach and 121 males from FVG general population. Factors associated with hair Hg content were investigated by multivariable logistic (considering Hg levels >1 vs ≤1 mg/kg) and log-transformed linear regression. The median hair concentration of Hg in male beach workers was 0.70 (IQR = 0.42; 1.34) mg/kg, lower than FVG general population's [1.29 (IQR = 0.87–2.06) mg/kg (p < 0.001)]. In both regression models the hair Hg increased with fish consumption, both among beach workers of Grado and FVG general population. The mean Hg levels in beach workers of Grado fell within an acceptable range, not requiring restrictions of their occupational activities.
Rapid thermoscanning technique for direct analysis of mercury species in contaminated sediments: From pure compounds to real sample application
2022, Applied Geochemistry
Mercury (Hg) in aquatic environments accumulates in sediments in several chemical forms, both inorganic and organic, which are often determined through time-consuming selective and sequential extraction procedures. Thermal desorption technique (pyrolysis) coupled with continuous determination by atomic absorption spectrometry (AAS) may be an easy-to-use alternative technique for the rapid identification and quantification of Hg species in the solid matrix. This technique is based on the gradual heating of a sample that releases Hg at different temperature intervals depending on its chemical form. Thus, a single Hg species that desorbs at a specific temperature may be identified via a thermogram of the sample.
In this work, several commercial pure Hg compounds, natural Hg mineral species (red cinnabar, α-HgS) and one compound synthesised in the lab (α-FeOOHHg) were mixed with synthetic calcium carbonate (CaCO₃), silica (SiO₂) and natural matrices (silicate and carbonate marine sediments) which were then desorbed in order to determine the desorption peak temperatures corresponding to each Hg species. Moreover, possible interference caused by the matrix was also considered. The results obtained from 52 desorbed MIX samples displayed different desorption temperatures for the same Hg species depending on the matrix used. Indeed, Hg species mixed with synthetic SiO₂ desorbed at a temperature lower than the same species mixed with synthetic CaCO₃ with a difference of approximately 100 °C.
The analytical approach was applied to selected coastal sediments from the Gulf of Trieste (Northern Adriatic Sea, Italy), contaminated by Hg from the five centuries of cinnabar (α-HgS) mining activity from Idrija (Slovenia), in order to identify the unknown Hg species. The results revealed the presence of two peaks with a distinct temperature of desorption (∼250 and 350 °C). The highest temperature corresponds to the mostly refractory red cinnabar (α-HgS) compound, whereas the lowest temperature is related to other species (e.g. β-HgS) that may also include Hg associated with more mobile and potentially bio-accessible species (e.g. α-FeOOHHg) if compared to α-HgS. This methodological approach is a rapid and cost-effective technique useful to preliminarily quantify more stable Hg species (mainly α-HgS), underlining the relevance in considering the chemical form of the element rather than merely the total concentration for simplifying the environmental management of Hg-contaminated sediments.
The role of hydrological conditions for riverine Hg species transport in the Idrija mining area
2019, Environmental Pollution
Estimation of mercury (Hg) species fluxes in Hg contaminated rivers is crucial to predict Hg methylation in connected sediment sinks. Cinnabar (HgS) was mined and roasted for ∼500 years in the Idrija mining area, Slovenia, which is drained by the Idrijca River to the Gulf of Trieste (GT), Italy. Mining residues dumped into the Idrijca River caused high proportions of cinnabar in sediments, whereas soils containing high proportions of natural organic matter bound to Hg (NOM-Hg) are attributed to atmospheric Hg deposition. Previous calculations of Hg fluxes have been based on the erosion of cinnabar only, and neglected transport of NOM-Hg derived from soil. Here, we estimated NOM-Hg and cinnabar fluxes in the Idrijca River and evaluated the extent of variability under changing hydrological conditions. We estimated the discharge of NOM-Hg by Idrijca's tributaries and the importance of NOM-Hg fluxes for Hg methylation in the GT. Mass balance calculations reveal that approximately 11.2 Mg y⁻¹ of NOM-Hg and 38.9 Mg y⁻¹ of cinnabar are transported by the Idrijca River to the GT under median-flow conditions. In the past 520 years, a total of 53,000 tons of Hg have been released from the Idrija mining area, of which ∼32,000 tons were NOM-Hg. Under low-flow conditions, Idrijca's tributaries deliver more than 1280 kg y⁻¹ of NOM-Hg. This study highlights the importance of Hg species analyses and their flux calculations to estimate risks of biological Hg uptake in sedimentary Hg sinks connected to Hg mining areas.
From point source to diffuse source of contaminants: The example of mercury dispersion in the Paglia River (Central Italy)
2019, Catena
Fluvial sediments of the Paglia River, a tributary of Tiber River (Central Italy), are contaminated by mercury (Hg) as a consequence of past mining activity (1846–1981, with main production 1900–1970) in the Monte Amiata district (the 3rd largest Hg producer worldwide). In this study, we combine a geomorphological analysis with geochemical data to try and understand the influence of fluvial dynamics on the spatial distribution of Hg in fluvial sediments over a 43 km segment of the river.
By considering the evolution of the river course between 1883 and 2013, eight different geomorphic units (GUs) were recognised, including the active channel bed (baseflow channel and bar), the floodplain, and five orders of terraces. The distribution of Hg in sediments of these GUs reflects the timing of their formation with respect to evolution of the mining activity. In GUs formed before the main peak of mining activity, or after mine closure, sediments show mean Hg contents comparable to, or slightly higher than, the local background, estimated at 2–6 mg/kg; in GUs formed during the peak production, Hg mean contents are definitely higher (up to 26 mg/kg). The current floodplain also shows high contents (mean 19 mg/kg), because of continuous reworking and transport of older contaminated sediments during major flood events. Therefore, the point contaminant sources represented by mining centres evolved into a diffuse source spread over several tens of kilometres.
By combining geochemical data with calculated sediment volumes, we estimate that not less than 63 tonnes of Hg are currently contained in the sediments of the investigated river stretch. Such amount of Hg will probably limit for the near future a full land use along the Paglia–Tiber course.

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Mercury in the Idrijca River sediments as a reflection of mining and smelting activities of the Idrija mercury mine

Abstract

J. Geochem. Explor.

Environmental studies in Western Europe using overbank sediment

Studies on the distribution and uptake of mercury in the area of mercury mine Idrija

Vestnik slovenskega kemijskega društva

Metal Pollution in the Aquatic Environment

Ocena vsebnosti ivega srebra v sedimentih Idrijce

Onesnaevanje in varstvo okolja, geologija in tehnika za okolje

Verteilung, Mobilität und Verfügbarkeit von Hg in Böden und Sedimenten am Beispiel zweier hochbelasteter Industriestandorte