Origin and structures of groundwater humic substances from three Danish aquifers

Grøn, C.; Wassenaar, Leonard I.; Krog, M.

doi:10.1016/0160-4120(96)00056-6

Cited by 50 publications

(33 citation statements)

References 42 publications

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“…Such occurrences are however extremely rare, the 95 percentile is below 10 mg C/L TOC for all Danish aquifer types. Organic carbon rich waters may be found both in deep aquifer systems (> 100 m below surface) like in the Danish cases (Grøn et al 1996, Jørgensen et al, 1999, Hinsby et al 2001) and in shallow soil, bog and aquifer sediments (e.g. Weis et al, 1989, Ernstsen et al 2005.…”

Section: Discussionmentioning

confidence: 99%

“…Weis et al, 1989, Ernstsen et al 2005. In case of doubts on the origin of the organic carbon further characterisation of the composition is needed (Weiss et al 1989, Grøn et al 1996.…”

Section: Discussionmentioning

confidence: 99%

“…Some of the more hydrophobic organic compounds present in surface and recharge waters will be sorbed onto the aquifer solids. Deeper and older waters may contain organic material which has been mobilised from the aquifer matrix (Grøn et al, 1996, Orem et al 1999) such as lower molecular weight compounds resulting from kerogen degradation or bitumen dissolution.…”

Section: Introductionmentioning

confidence: 99%

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Organic Quality of Groundwaters

Gooddy

Hinsby

2008

Natural Groundwater Quality

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Organic carbon is present in all natural waters and plays an important role in many geochemical processes. Total organic carbon (TOC), measured on unfiltered samples, has been analysed on more than 400 groundwater samples from 8 European Union countries, and the operationally defined dissolved organic carbon (DOC), measured on filtered samples, was analysed on approximately 250 groundwater samples from 4 of these countries. TOC was found at a median concentration of 2.7 mg C/L with a range from 0.1 -59.4 mg C/L and DOC had a median concentration of 2.2 mg C/L with a range from 0.2 -58.9 mg C/L, demonstrating that very high natural organic carbon values can occasionally be found locally in some pristine aquifers. A relationship between the assimilable organic carbon (AOC) utilised by bacteria and TOC is observed although the correlation is not clear. Generally, there is a linear correlation between the TOC, DOC and the chemical oxygen demand (COD) values. Organic contaminants derived from anthropogenic activities are generally not identified in the TOC/DOC analysis as these contaminant concentrations are typically several orders of magnitude lower than the bulk aqueous carbon measurement. TOC/DOC analysis can, however be an important indicator of pollution at landfills, effluent ponds and similar pollution settings with high loads of organic carbon, but in many other situations the total or dissolved organic carbon concentration is not a good tracer or indicator of contamination. However, the total or dissolved organic carbon is a very important component in the biogeochemical cycling of elements and consequently it is recommended as a component to be measured on all groundwater samples. The measurement of a filtered organic carbon fraction is recommended where groundwaters contain significant amounts of particulate material. Measurements of TOC and DOC on the same samples in this study show comparable concentrations, however, the TOC/DOC ratio varied and TOC was not always found to be significantly greater than DOC, as may have been expected. Further investigations are needed to find the reasons for this. Further research is also needed to evaluate what part of the TOC is readily available for biogeochemical processes. Increased knowledge on this issue would help to understand better the development of the different redox environments and associated bacterial regrowth which occurs in water supply systems.

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Section: Discussionmentioning

confidence: 99%

“…Weis et al, 1989, Ernstsen et al 2005. In case of doubts on the origin of the organic carbon further characterisation of the composition is needed (Weiss et al 1989, Grøn et al 1996.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Organic Quality of Groundwaters

Gooddy

Hinsby

2008

Natural Groundwater Quality

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“…Humic substances are divided into humic acids and fulvic acids based on differences in elemental characteristics and chemical properties (16)(17)(18)(19)30). Recently, humic substances from the Skagen aquifer were characterized in detail (18,30). The analyses included size exclusion chromatography, fluorescence spectroscopy, nuclear magnetic resonance spectroscopy, determination of dissolved organic carbon, amino acid and elemental composition, and isotope analyses.…”

Section: Discussionmentioning

confidence: 99%

“…They are produced in sediments in the decay process of plant and animal tissues as an intermediate step in the eogenetic pathway from higher plant material to kerogen and eventually coal (16,20). Humic substances are divided into humic acids and fulvic acids based on differences in elemental characteristics and chemical properties (16)(17)(18)(19)30). Recently, humic substances from the Skagen aquifer were characterized in detail (18,30).…”

Section: Discussionmentioning

confidence: 99%

Iodine in drinking water in Denmark is bound in humic substances

Andersen

Petersen

Laurberg

2002

European Journal of Endocrinology

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Objective: The iodine intake level is important for the occurrence of thyroid disorders in a population. We have previously found that iodine in drinking water is related to iodine excretion but whether iodine is present as iodide or bound in other molecules remains unknown. Design: We measured iodine in drinking water from 22 locations in Denmark. Six locations were selected by iodine content for further tap water analysis (Skagen 140 mg/l, Samsoe 56 mg/l, Nykoebing S. 50 mg/l, Nakskov 40 mg/l, Ringsted 38 mg/l, Copenhagen 19 mg/l). Methods: HPLC size exclusion before (Skagen) and after (all sites) freeze drying and measurement of absorbance (280 nm) and iodine in fractions, and fluorescence spectroscopy of bulk organic matter in Skagen drinking water. Results: Iodine content was unaltered after 3 years ðP ¼ 0:2Þ: All samples contained organic molecules with characteristics similar to humic substances. Most iodine eluted with humic substances (Skagen 99%, Ringsted 98%, Nykoebing S. 90%, Copenhagen 90%, Samsoe 75%, Nakskov 40%). Changing pH and ionic strength and preincubation with iodide indicated that iodine was bound in humic substances. Humic substances may affect thyroid function but differ with geology. Geological and geochemical data agree with tap water humic substances having been released from marine deposits. Iodine is abundant in the marine environment and marine deposits are particularly rich in iodine. Correlation analysis ðr ¼ 0:85; P ¼ 0:03Þ conform to iodine in drinking water, suggesting marine humic substances at the source rock. Conclusion: Iodine in Danish drinking water varied considerably. In drinking water with a high iodine content, the iodine mainly eluted with humic substances derived from marine source rock. We hypothesize that iodine in drinking water in general suggests coexisting humic substances of marine origin.

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