Sediment and Aqueous Geochemistry Laboratory

Analyses are offered to researchers (internal and external), companies and research partners. The laboratory is used for the education of bachelor, graduate and PhD students. The analyses are made by the users themselves under supervision, or by qualified laboratory technicians with quality assurance and quality control (QA/QC) in collaboration with the responsible researcher. 

Sedimentary geochemistry

The sedimentary geochemistry includes rockdrilling and sample preparation of sediments and sedimentary rocks (rock cutting, crushing and decarbonation).

Our backpack portable core drill permit us to easily take pristine unweathered drill cores to a depth of 12 m in hard accessible remote places with minimal environmental impact. (PHOTO)

We analyse major elements such as inorganic and organic carbon, sulfur, iron and phosphorus by various chemical methods. Sample cores and powders are analysed non-destructively by hand-held portable X-Ray Fluorescence (XRF) analysis and Fourier Transform Infrared Spectroscopy (Diffuse reflectance FTIR).

We also perform iron and phosphorus speciation by wet chemical sequential extraction and analysis by ICP-OES and spectrophotometry as well as pyrite extraction by chromium reduction in a distillation setup. (PHOTO)

 

Portable core drill permitting drilling to 12−15 m depending on conditions
- Drill, bit and core barrels from Shaw portable core drill

Pretreatment, such as crushing in planetary ball mill, freeze drying and decarbonation
- Equipment: Retsch PM 100 Planetary ball mill, Scanvac Coolsafe Freezedrier, VWR Mega Star 1.6 Centrifuge

Determination of total carbon- and sulphur content (TOC after decarbonation)
- Equipment: Thermo Scientific IRMS instruments
- Method: C,N,S by continuous flow Elemental Analyzer

Determination of carbonate by titration
- Equipment: Metrohm 855 Robotic Titrosampler, PC-controlled with Tiamo software

Determination of water content and loss on ignition (LOI)
- Equipment: Carbolite RHF1400 Furnace, drying oven

X-ray fluorescence major- and trace element analysis
- Equipment: Delta Premium, handheld XRF analyzer
- Reference: Ahm, A.-S. C., Bjerrum, C. J., and Hammarlund, E. U., 2017., Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation: Earth and Planetary Science Letters, v. 459, p. 145-156.

Sequential extraction of iron:
- Equipment: Thermo iCAP 7400 Duo ICP-OES analyzer, IKA Trayster digital overhead shakers.
- Method: Extraction of iron carbonates, reducable iron oxides and magnetite with different buffer solutions.
- Reference: Alcott, L. J., Krause, A. J., Hammarlund, E. U., Bjerrum, C. J., Scholz, F., Xiong, Y. J., Hobson, A. J., Neve, L., Mills, B. J. W., Marz, C., Schnetger, B., Bekker, A., and Poulton, S. W., 2020., Development of Iron Speciation Reference Materials for Palaeoredox Analysis: Geostandards and Geoanalytical Research, v. 44, no. 3, p. 581-591.

Extraction of pyrite (iron sulfide)
- Equipment: In house custom Distillation setup with heating mantels and nitrogen flow.
- Method: Distillation with reducing chromium solution.
- Reference: Alcott, L. J., Krause, A. J., Hammarlund, E. U., Bjerrum, C. J., Scholz, F., Xiong, Y. J., Hobson, A. J., Neve, L., Mills, B. J. W., Marz, C., Schnetger, B., Bekker, A., and Poulton, S. W., 2020., Development of Iron Speciation Reference Materials for Palaeoredox Analysis: Geostandards and Geoanalytical Research, v. 44, no. 3, p. 581-591.

Canfield, D.E., Raiswell, R., Westrich, J.T., Reaves, C.M. and Berner, R.A., 1986. The use of chromium reduction in the analysis of reduced inorganic sulfur in sediments and shales. Chem. Geol., 54: 149–155.

 

Aqueous geochemistry

The aqueous geochemistry includes analyses of inorganic constituents in fresh and saline groundwater as well as surface waters using ion chromatography (IC), spectrophotometry, titration and measurement of pH, oxygen and conductivity. This enables studies of carbon and nutrient cycling in the hydrosphere, such as studies of denitrification, groundwater phosphorus transport towards surface waters, and of carbon cycling in permafrost regions.

 

Aqueous geochemistry

Determination of alkalinity
- Equipment: Metrohm 855 Robotic Titrosampler, PC-controlled with Tiamo software.
- Method: End-point titration with autotitrator.
- Reference: DS/EN ISO 9963-2.

Determination af bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate
- Equipment: Dionex Aquion IC system with RFC-30 eluent-generator and AS-AP autosampler.
- Method: Ion chromatography with KOH eluent, IonPac AS19 250 / 2.0mm column and electrolytically regenerated suppressor.
- Reference: ISO 10304-1.

Determination of sodium, potassium, calcium, magnesium, iron, manganese and aluminum
- Equipment: Thermo iCAP 7400 Duo ICP-OES analyzer.
- Method: Determination of acidified samples on ICP-OES analyzer.
- Reference: ISO 11885.

Spectrophotometric determination of ferro-iron (Fe2+)
- Equipment: Biotek EPOCH 2 plate reader with cuvette holder or transportable field spectrophotometer, HACH.
- Method: Formation of stable magenta complex with Ferrozine. The absorbance of the complex at 562 nm is proportional to the Fe2 + content.
- Reference: Stookey, L. L., 1970: Ferrozine - a new spectrophotometric reagent for iron. Analytical Chemistry 42, 779-781.

Spectrophotometric determination of sulfide:
- Equipment: Biotek EPOCH 2 plate reader with cuvette holder or transportable field spectrophotometer, HACH.
- Method: Formation of methylene blue complex with diamine reagent. The absorbance of the complex at 670 nm is proportional to the sulphide content.
• Reference: DS 278 and Cline, J. D., 1969: Spectrophotometric determination of hydrogen sulfide in natural waters. Limnology and Oceanography 14, 454-458.

Spectrophotometric determination of orthophosphate:
- Equipment: Biotek EPOCH 2 plate reader with cuvette holder or transportable field spectrophotometer, HACH.
- Method: Formation of molybdenum blue complex with ammonium molybdate. The absorbance of the complex at 880 nm is proportional to the orthophosphate content.
• Reference: DS/EN 1189.

Fotometrisk Determination af ammonium:
- Equipment: Biotek EPOCH 2 plate reader with cuvette holder or transportable field spectrophotometer, HACH.
- Method: In the presence of sodium nitroprusside, ammonium in weak alkaline solution reacts with salicylate and hypochlorite to form indophenol blue. The absorbance of the complex at 650 nm is proportional to the ammonium content.
- Reference: DS 224 and NOVA - Technical instructions for marine monitoring - 14. Sediment - oxygen and nutrients, Appendix 14.6.

PH, conductivity and oxygen measurement:
- Equipment: Portable measuring instruments for field use.