Advanced

Stratigraphy and pyrite geochemistry of the Lower–Upper Ordovician in the Lerhamn and Fågelsång-3 drill cores, Scania, Sweden

Balija, Fisnik LU (2018) In Dissertations in geology at Lund University GEOR02 20181
Department of Geology
Abstract (Swedish)
Arsenik är ett mycket giftigt ämne som finns i berg, mark och grundvatten, och är känt för att orsaka allvarliga hälsoeffekter. Neurologiska skador hos människan inträffar vid koncentrationer så låga som 100 μg/L, medan 1–3 mg/kg kroppsvikt As är en dödlig dos. Exponering för As kan leda till bland annat cell- och DNA-skador, ett antal sjukdomar och störningar samt olika typer av cancer. Höga As-koncentrationer kan uppstå i närvaro av sulfidmineral, såsom pyrit (FeS2). Diagenetisk pyrit finns vanligen i skiffer och bildades i stor
omfattning under ordovicium, till följd av låga C/S-förhållanden. Förutom As så är pyrit även känt för att innehålla tungmetaller. En pilotstudie vid Lunds universitet visade med hjälp av XRF-analys en... (More)
Arsenik är ett mycket giftigt ämne som finns i berg, mark och grundvatten, och är känt för att orsaka allvarliga hälsoeffekter. Neurologiska skador hos människan inträffar vid koncentrationer så låga som 100 μg/L, medan 1–3 mg/kg kroppsvikt As är en dödlig dos. Exponering för As kan leda till bland annat cell- och DNA-skador, ett antal sjukdomar och störningar samt olika typer av cancer. Höga As-koncentrationer kan uppstå i närvaro av sulfidmineral, såsom pyrit (FeS2). Diagenetisk pyrit finns vanligen i skiffer och bildades i stor
omfattning under ordovicium, till följd av låga C/S-förhållanden. Förutom As så är pyrit även känt för att innehålla tungmetaller. En pilotstudie vid Lunds universitet visade med hjälp av XRF-analys en As-anomali med förhöjda koncentrationer i en ordovicisk skiffer från Lerhamnsborrningen i nordvästra Skåne. I denna uppföljningsstudie görs en mer detaljerad geokemisk analys med fokus på pyrit från Lerhamnsborrkärnan med hjälp av LA-ICP-MS, för högre precision och noggrannare resultat. En annan borrkärna (Fågelsång-3) med ordoviciska skiffrar från Fågelsångsområdet i sydvästra Skåne, används för en jämförelse av resultat. Förutom As så är även ett antal tungmetaller av intresse. Analyserna bekräftar höga koncentrationer av As och även höga halter av några tungmetaller (V, Cr, Co, Mo, Cd, Sb, W, Hg, Pb) i pyrit i båda borrkärnorna. Dock så observeras en tydlig As-anomali endast i Lerhamnsborrkärnan, med mycket höga halter omkring 40 m djup. Den genomsnittliga
As-koncentrationen är ca 736 ppm i Lerhamnsborrkärnan och 268 ppm i Fågelsång-3-borrkärnan, med maximala värden på 17660 ppm respektive 2295 ppm. Det föreligger emellertid inga risker så länge dessa skifferlagerföljder inte utsätts för erosion och vittring. Däremot finns det en potentiell risk för lokal As-förorening av miljön om skiffer/pyrit med höga As-koncentrationer, särskilt från Lerhamn, exploateras och pyriten utsätts för oxidation. Pyriten skulle då brytas ned och As och tungmetaller frigöras. (Less)
Abstract
Arsenic is a very toxic element present in rocks, soils, and natural groundwater, and known to cause serious health effects. Neurological damage is known in humans to occur at concentrations as low as 100 μg/L, while 1–3 mg/kg of body weight As is a lethal dose. Exposure to As may lead to e.g. cellular injury and DNA damage, a number of diseases and disorders and several types of cancer. High concentrations of As can be produced in the presence of sulfide minerals, such as pyrite (FeS2). Diagenetic pyrite is commonly found in shale and formed at high rates during the Ordovician Period, favored by low C/S ratios. In addition to As, pyrite is also known to incorporate heavy metals. A pilot study at Lund University, using XRF-analysis, have... (More)
Arsenic is a very toxic element present in rocks, soils, and natural groundwater, and known to cause serious health effects. Neurological damage is known in humans to occur at concentrations as low as 100 μg/L, while 1–3 mg/kg of body weight As is a lethal dose. Exposure to As may lead to e.g. cellular injury and DNA damage, a number of diseases and disorders and several types of cancer. High concentrations of As can be produced in the presence of sulfide minerals, such as pyrite (FeS2). Diagenetic pyrite is commonly found in shale and formed at high rates during the Ordovician Period, favored by low C/S ratios. In addition to As, pyrite is also known to incorporate heavy metals. A pilot study at Lund University, using XRF-analysis, have shown an As-anomaly with elevated concentrations in an Ordovician shale from a drill core obtained in the Lerhamn area, northwestern Scania, southern Sweden. In this follow-up study a deeper geochemical analysis with focus on pyrite from the Lerhamn drill core is done using LA-ICP-MS, for high precision and accurate results. A second drill core (Fågelsång-3) retrieved from Ordovician shales in the Fågelsång area, south-west Scania, is also investigated for a comparison of the result. In addition to As a number of heavy metals are also of interest. The analytical results confirm high concentrations of As, including some of the heavy metals (V, Cr, Co, Mo, Cd, Sb, W, Hg, Pb), in both drill cores. However, a single significant As-anomaly is only observed in the Lerhamn drill core peaking at around 40 m depth. The average As concentration is approximately 736 ppm in the Lerhamn drill core and 268 ppm in the Fågelsång-3 drill core, with highest values ranging up to 17660 ppm and 2295 ppm, respectively. This study concludes that the relatively high As concentrations in the Lerhamn and Fågelsång shale is of no concern in its present location. However, there is a potential risk for local As-contamination of the environment if shale/pyrite with high As concentrations, in particular from Lerhamn, is exposed to surface conditions. The pyrite would readily oxidize, and As and heavy metals be released. (Less)
Please use this url to cite or link to this publication:
author
Balija, Fisnik LU
supervisor
organization
course
GEOR02 20181
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Ordovician, shale, drill cores, arsenic, pyrite, heavy metals, Lerhamn, Fågelsång, Scania, Sweden.
publication/series
Dissertations in geology at Lund University
report number
530
language
English
id
8939464
date added to LUP
2018-05-14 13:55:46
date last changed
2018-05-14 13:55:46
@misc{8939464,
  abstract     = {Arsenic is a very toxic element present in rocks, soils, and natural groundwater, and known to cause serious health effects. Neurological damage is known in humans to occur at concentrations as low as 100 μg/L, while 1–3 mg/kg of body weight As is a lethal dose. Exposure to As may lead to e.g. cellular injury and DNA damage, a number of diseases and disorders and several types of cancer. High concentrations of As can be produced in the presence of sulfide minerals, such as pyrite (FeS2). Diagenetic pyrite is commonly found in shale and formed at high rates during the Ordovician Period, favored by low C/S ratios. In addition to As, pyrite is also known to incorporate heavy metals. A pilot study at Lund University, using XRF-analysis, have shown an As-anomaly with elevated concentrations in an Ordovician shale from a drill core obtained in the Lerhamn area, northwestern Scania, southern Sweden. In this follow-up study a deeper geochemical analysis with focus on pyrite from the Lerhamn drill core is done using LA-ICP-MS, for high precision and accurate results. A second drill core (Fågelsång-3) retrieved from Ordovician shales in the Fågelsång area, south-west Scania, is also investigated for a comparison of the result. In addition to As a number of heavy metals are also of interest. The analytical results confirm high concentrations of As, including some of the heavy metals (V, Cr, Co, Mo, Cd, Sb, W, Hg, Pb), in both drill cores. However, a single significant As-anomaly is only observed in the Lerhamn drill core peaking at around 40 m depth. The average As concentration is approximately 736 ppm in the Lerhamn drill core and 268 ppm in the Fågelsång-3 drill core, with highest values ranging up to 17660 ppm and 2295 ppm, respectively. This study concludes that the relatively high As concentrations in the Lerhamn and Fågelsång shale is of no concern in its present location. However, there is a potential risk for local As-contamination of the environment if shale/pyrite with high As concentrations, in particular from Lerhamn, is exposed to surface conditions. The pyrite would readily oxidize, and As and heavy metals be released.},
  author       = {Balija, Fisnik},
  keyword      = {Ordovician,shale,drill cores,arsenic,pyrite,heavy metals,Lerhamn,Fågelsång,Scania,Sweden.},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in geology at Lund University},
  title        = {Stratigraphy and pyrite geochemistry of the Lower–Upper Ordovician in the Lerhamn and Fågelsång-3 drill cores, Scania, Sweden},
  year         = {2018},
}