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Dive into the research topics where Jens Christian Tjell is active.

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Featured researches published by Jens Christian Tjell.


British Journal of Dermatology | 1978

Low nickel diet in the treatment of patients with chronic nickel dermatitis

K. Kaaber; N. K. Veien; Jens Christian Tjell

Of 28 patients with chronic nickel dermatitis 17 experienced aggravation following oral ingestion of 2.5 mg nickel, but not a placebo tablet. The dermatitis of 9 of the 17 patients improved during a period of 6 weeks on a low nickel diet. The dermatitis of 7 of the 9 patients flared again when a normal diet was resumed.


Journal of Colloid and Interface Science | 2003

Adsorption of arsenate from water using neutralized red mud

Hülya Genç; Jens Christian Tjell; David McConchie; Olaf Schuiling

The potential for using seawater-neutralized red mud (Bauxsol), a waste from aluminum manufacturing, as an adsorbent for removing As(V) (arsenate) from water is studied. Herein, adsorption characteristics are investigated and it is shown that adsorption follows the Langmuir model, with the adsorption constants indicating the feasibility of the process. Furthermore, the adsorption is found to increase with decreasing pH (i.e., ligand-like adsorption), higher adsorbent dosages, and lower initial arsenate concentrations. The effects of ions are also tested and it is shown that the adsorption of arsenate decreases in the presence of HCO3-, while Cl- has little effect, and Ca2+ increases the adsorption. Water quality assessment after treatment with Bauxsol indicates that none of the trace elements tested are released from the adsorbent. A TCLP leaching test also reveals that the used adsorbent is not toxic. It is foreseen that Bauxsol may be developed into an efficient low-cost adsorbent for (pre-) treating arsenate contaminated waters.


Applied Geochemistry | 2002

The solubility of rhodochrosite (MnCO3) and siderite (FeCO3) in anaerobic aquatic environments

Dorthe Lærke Jensen; Jens K. Boddum; Jens Christian Tjell; Thomas Højlund Christensen

Abstract Natural groundwaters are often reported to be highly supersaturated with the carbonate minerals siderite (FeCO 3 ) and rhodochrosite (MnCO 3 ). The kinetics of precipitation and dissolution were determined in the light of new determinations of the solubility products of siderite and rhodochrosite. Laboratory experiments showed that the precipitation kinetics of siderite and rhodochrosite were much slower than that of calcite, and also much slower than their dissolution kinetics. Experiments with supersaturated solutions failed to reach steady state within 474 days in the case of siderite, whereas steady state for rhodochrosite was reached after 140 days. Suspensions of siderite and rhodochrosite crystals reached steady state after 10 and 80 days, respectively. The solubility product of siderite (−log K S0 (FeCO 3 )) was 11.03 ± 0.10 for dried crystals and 10.43 ± 0.15 for wet crystals. For rhodochrosite the solubility product (−log K S0 (MnCO 3 )) was 11.39 ± 0.14 for dried crystals and 12.51 ± 0.07 for wet crystals. The solubility product determined from supersaturated solutions was −log K S0 (MnCO 3 )=11.65 ± 0.14. The observed slow precipitation kinetics of siderite and rhodochrosite might explain the apparent supersaturation that is often reported for anaerobic aquatic environments.


Environmental Science & Technology | 1994

Oxidation capacity of aquifer sediments

Gorm Heron; Thomas Højlund Christensen; Jens Christian Tjell

A laboratory extraction method (Ti 3+ -EDTA extraction) for the determination of the oxidation (electron accepting) capacity related to oxides and hydroxides of aquifer sediments was developed. At room temperature, titanous ions (0.008 M Ti 3+ ) in a solution of 0.05 M ethylenediaminetetraacetic acid (EDTA) reduced oxidized aquifer species. This operationally defined oxidation capacity (ORC) was determined as μmoles of electrons accepted per gram of sediment sample. Well-described oxidized iron and manganese minerals were reduced (ferrihydrite 98%, akageneite 100%, goethite and hematite 93%,magnetite 9%, pyrolmite 99%) whereas organic matter in the sediments was not reduced significantly


Water Science and Technology | 1997

Pollution of soil and groundwater from infiltration of highly contaminated stormwater - a case study

Peter Steen Mikkelsen; M. Häfliger; M. Ochs; Per Jacobsen; Jens Christian Tjell; Markus Boller

A surface and a sub-surface infiltration system that received runoff water from trafficked roads for several decades was dug up and the contamination with heavy metals, PAH and AOX was investigated. Most measured solid phase concentrations exceeded background concentrations in nearby surface soils and sub-surface sediments and some even exceeded guidelines fixed to preserve the fertility of soil. However, the contamination decreased rapidly with depth. None of the measured metal concentrations in simulated soil solutions exceeded defined drinking water quality standards. Surprisingly, the surface and the sub-surface infiltration system seemed to be equally good at retaining pollution. This indicates that the runoff sludge found in such infiltration systems plays an important role both as a source and a sorbent for stormwater contaminants. The study does not point at a considerable risk for groundwater contamination due to stormwater infiltration, but highlights that well absorbable contaminants readily available in urban stormwater runoff eventually build up in surface soils and sub-surface sediments to environmentally critical concentration levels. Thus, on the one hand stormwater infiltration systems may act as effective pollution traps and on the other, they may pose a potential solid waste disposal problem that future stormwater management based on local infiltration will have to face.


Science of The Total Environment | 2002

Composition of human excreta: a case study from Southern Thailand

Nanette L.. Schouw; Somtip Danteravanich; Hans Mosbæk; Jens Christian Tjell

In Thailand, human excreta might be recycled into agricultural soils as a supplement to commercial fertiliser and thereby enrich the general fertility of the soils. However, for Thailand an adequate knowledge of the quality of human excreta, in order to assess its fertiliser potential, is not available. A literature survey revealed only very limited information of the chemical composition and generation rate of human excreta in South East Asia. Data from other parts of the world also lacked specific information on collection and analytical methods, or the studies were typically 20-30 years old. In the present study the composition of human excreta has been studied in three case study areas in Southern Thailand: Kuan Lang, Phattalung and Prik. The inhabitants of the three areas represent people of Southern Thailand by age, sex, occupation, religion and type of residence. Human excreta was collected and stored for 1 week from five persons in each area, who each had their own toilet and collection bucket. In parallel, a septic tank at the Observation and Protection (O&P) Centre of Songkhla (a boys prison institution) adjacent to the three study areas was used as a daily sampling point, to obtain data on average amounts of human excreta and chemical composition. Information on average values of generation rate and chemical composition was obtained as well as inter-human variation. However, no significant variation was found between the results for human excreta at the O&P Centre or from the 15 individuals. Furthermore, there was no significant influence of age, sex, occupation or religion on the chemical composition. The only significant variation was that the older people excreted larger amounts of total wet matter than the younger, which could be due to a higher water intake, in order to reduce the risk of constipation. The generation rate found was 0.6-1.2 1 urine/cap/day and 120-400 g wet faeces/cap/day. The generation rate of the elements in the excreta was 7.6-7.9 g N/cap/day, 1.6-1.7 g P/cap/day, 1.8-2.7 g K/cap/day, 1.0-1.1 g S/cap/day, 0.75-1.5 g Ca/cap/day, 0.25-0.4 g Mg/cap/day, 9-16 mg Zn/cap/day, 1.4-1.5 mg Cu/cap/day, 0.3 mg Ni/cap/day, 0.02-0.03 mg Cd/cap/day, 0.07-0.14 mg Pb/cap/day, 0.01 mg Hg/cap/day and 0.8-1.1 mg B/cap/day. The metals (Ca, Mg, Zn, Cu, Ni, Cd, Pb, Hg) are mainly excreted via the faeces and the remaining elements (N, P, K, S, B) are mainly excreted via the urine. It can be concluded that human excreta constitutes a large fertiliser resource, which presently is not utilised in Thailand.


Contact Dermatitis | 1979

Antabuse treatment of nickel dermatitis. Chelation-a new principle in the treatment of nickel dermatitis

Knud Kaaber; Torkil Menné; Jens Christian Tjell; Niels K. Veien

Eleven nickel‐hypersensitive patients with chronic, dyshidrotic hand eczema aggravated by oral challenge with 0.6–2.5 mg nickel were treated with 100 mg tetraethylthiuramdisulfide (Antabuse®) two to four times daily for 4–10 weeks.


Science of The Total Environment | 1996

Experimental assessment of soil and groundwater contamination from two old infiltration systems for road run-off in Switzerland

Peter Steen Mikkelsen; M. Häfliger; M. Ochs; Jens Christian Tjell; Per Jacobsen; M. Boller

Surface and sub-surface infiltration systems for road run-off at two sites in Switzerland were investigated by sampling and analysing the run-off sludge and soil found in the systems. The infiltration systems were between 12 and 45 years old. Measured pollutant parameters included the heavy metals Cr, Co, Ni, Cu, Zn, Cd and Pb, a number of polycyclic aromatic hydrocarbons (PAH) and adsorbed organically bound halogens (AOX). Total concentrations were measured to assess the extent of soil contamination. Further, metal concentrations were measured in equilibrated aqueous extracts to simulate naturally occurring concentrations in percolating water. In the infiltration systems the pollutant concentrations decreased rapidly to background levels within depths less than 1.5 m. The potential for groundwater contamination from infiltration of road run-off appears to be limited, but soil and run-off sludge found in infiltration systems can be heavily contaminated. Noteworthy, the run-off sludge itself plays an important role as pollutant source and sorbent.


Rubber Chemistry and Technology | 1999

Quantification of tire-tread particles using extractable organic zinc as tracer

Patrik Fauser; Jens Christian Tjell; Hans Mosbæk; Kim Pilegaard

Abstract A method for identifying and quantifying tire-tread particles in the environment has been developed. It is based on the measurement of extractable organic zinc. The high sensitivity of atomic absorption spectrometry (AAS) with a heated graphite atomizer (HGA) permits assessment of submilligram amounts of tire debris in environmental samples. The analysis is performed on aerosol and soil samples. This new method is more accurate and faster than the previously reported IR method.


Plant and Soil | 1986

Lead and cadmium content of Indian flue-cured tobacco

K. S. N. Murty; Jens Christian Tjell; N. C. Gopalachari

SummaryStudies on levels of lead and cadmium of Indian flue-cured tobacco indicated that the leaf contained very low amounts of these heavy metals as compared to tobacco from other countries. Indian tobacco can therefore be adjudged as ‘safe and clean’ and least hazardous to the smoker. Of the two heavy metals, lead content of soils is higher than cadmium. But in the leaf, cadmium content is more than lead indicating that soil cadmium may be more available to tobacco and hence more readily absorbed by the plant than lead.

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Hans Mosbæk

Technical University of Denmark

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Anitha Kumari Sharma

Technical University of Denmark

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Nanette L.. Schouw

Technical University of Denmark

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Patrik Fauser

Technical University of Denmark

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Peter Kjeldsen

Technical University of Denmark

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Kim Pilegaard

Technical University of Denmark

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Somtip Danteravanich

Prince of Songkla University

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Dorthe Lærke Jensen

Technical University of Denmark

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