Biomedical subjects

Clemens Reimann

Publications and source records attributed to Clemens Reimann.

10 recordsLinked to original sources

PubMed2006

PAH-concentrations and compositions in the top 2 cm of forest soils along a 120 km long transect through agricultural areas, forests and the city of Oslo, Norway.

The top 2 cm of forest soils were collected along a 120 km long south-north transect running through Norway's largest city Oslo. Forty samples were analysed for their polycyclic aromatic hydrocarbon (PAH(16) as defined by the U.S. Environmental Protection Agency) concentrations and compositions. Local variations in the PAH values are high and the reported concentrations are in general low (maximum sumPAH16: 2.6 mg/kg). The transect shows distinct differences of sumPAH16 values from south to north. PAH concentrations are substantially lower in the less populated areas at the north end of the transect than at the urbanised and much more populated south end. Several high values occur in a forested area to the north of Oslo, used for recreation purposes. The PAH distribution patterns point towards a predominantly pyrogenic origin. Local Cambrian carbon-rich black shales can be excluded as sources for PAHs in the forest soils.

Agriculture↗

PubMed2006

The influence of a city on element contents of a terrestrial moss (Hylocomium splendens).

Forty terrestrial moss (Hylocomium splendens) samples were collected along a 120-km-long south-north transect running through Norway's largest city Oslo. Concentrations of 29 chemical elements (Ag, Al, Au, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, Pt, S, Sb, Sr, Th, Ti, and Zn) and values for loss on ignition (475 degrees C) are reported. Silver (Ag), Al, Au, Bi, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Pt, Sb, Th, Ti, and Zn all show a characteristic Oslo peak when element concentrations are plotted against location of the sample site along the transect. Gold (Au) and Pt show the greatest relative enrichment of all elements in the city (ca. 10x "background"). Titanium (Ti), which is related to local minerogenic dust rather than anthropogenic emissions, shows a significant peak in Oslo. Loss on ignition, a measure of the amount of organic material in a sample, shows a negative peak in Oslo and at sites close to a known dust source. Input of fine dust thus appears to dominate many of the observed element concentrations in moss. The concentrations of Na are clearly influenced by the input of marine aerosols and show decreasing concentrations from south (near Oslo Fjord) to north (inland). The major plant nutrients Ca, K, Mg, P and S, as well as Hg, are the few elements displaying no spatial dependency along the transect. Element concentrations reach background variation levels at a distance of 20-40 km from the city centre.

Adsorption↗

PubMed2006

Groundwater contamination from well points -- an experience from the Norwegian groundwater monitoring network.

Until 2005 the observation wells of the Norwegian Groundwater Monitoring Network in Quaternary aquifers were equipped with metal well points with brass lining. A laboratory leaching test using a new well point demonstrated that the well point material (galvanized iron pipe), the brass lining and the solder used to fix the lining could cause substantial contamination of the collected well water with a long list of chemical elements (Sn, Zn, Pb, Sb, Cd, Fe, Cu, Mn and Al), depending on well capacity, contact time water/well point and pH. Because groundwater chemistry is receiving increased attention in groundwater monitoring all wells were equipped with high density polyethylene (HDPE) points during the years 2004-2005. The HDPE points did not return any values above detection in a similar leaching test, with some minor values of Zn being the only exception.

Environmental Monitoring↗

PubMed2005

The geographic distribution of fluoride in surface and groundwater in Ethiopia with an emphasis on the Rift Valley.

This paper analyzes the most extensive database on fluoride distribution in Ethiopia. Of the total 1438 water samples tested, 24.2% had fluoride concentrations above the 1.5 mg/l recommended optimum concentration recommended by WHO. Regionally, by far the highest fluoride levels were recorded in the Rift Valley, where 41.2% of all samples exceeded the 1.5 mg/l level. Only 1.0% of the samples from the central and northwestern highlands and 10.0% in the southeastern highlands exceeded 1.5 mg/l. Larger proportions of deep wells (50.0%) and hot springs (90.0%) than shallow wells (27.2%) and cold springs (12.6%) exceeded the 1.5 mg/l level. The highest fluoride concentrations were recorded for Rift Valley lakes Shala (264.0 mg/l) and Abijata (202.4 mg/l) and the lowest in Lake Tana, and rivers, wells and springs in the highlands. The fluoride concentrations of the Awash River, which originates in the highlands and flows through the Rift Valley, increase downstream, giving concern over the current diversion of high-fluoride water from Lake Beseka. Of the various flourosis prevention methods tried in Ethiopia, the treatment of surface water has been shown to be the most feasible and effective for towns and large commercial farms in the Rift Valley, although defluoridation methods should be considered for smaller rural communities.

Environmental Monitoring↗

PubMed2005

Geochemical background--concept and reality.

The definitions and use of the term 'background' in exploration and environmental geochemistry are reviewed. Based on data from two subcontinental-scale geochemical mapping projects, it is shown that trying to define 'a background' for a large area is fraught with problems. It is demonstrated that background may change from area to area within a region and between regions. Although global averages are of general use, no specific global background levels of elements, for example in soils, can be defined, at best regional or local operational estimates can be made, though with caveats. Using background estimates based on concentrations in deeper soil levels to judge element concentrations in upper soil horizons (e.g., the TOP/BOT-ratio) can lead to severe misinterpretations if natural biogeochemical soil formation processes are ignored. Because of large natural variations in element concentrations in, for example soils, even the establishment of maximum admissible concentration based on ecotoxicological investigations is a difficult exercise. Organisms may become adapted to natural differences. Furthermore, there are challenges in converting the concentrations of the soluble substances used in ecotoxicological studies to appropriate levels in solid phase material, for example soils, analysed by commonly employed acid digestion procedures. Toxicological thresholds may thus also need to consider a spatial component that is presently neglected.

Elements↗

PubMed2005

Background and threshold: critical comparison of methods of determination.

Different procedures to identify data outliers in geochemical data are reviewed and tested. The calculation of [mean+/-2 standard deviation (sdev)] to estimate threshold values dividing background data from anomalies, still used almost 50 years after its introduction, delivers arbitrary estimates. The boxplot, [median+/-2 median absolute deviation (MAD)] and empirical cumulative distribution functions are better suited for assisting in the estimation of threshold values and the range of background data. However, all of these can lead to different estimates of threshold. Graphical inspection of the empirical data distribution using a variety of different tools from exploratory data analysis is thus essential prior to estimating threshold values or defining background. There is no good reason to continue to use the [mean+/-2 sdev] rule, originally proposed as a 'filter' to identify approximately 2(1/2)% of the data at each extreme for further inspection at a time when computers to do the drudgery of numerical operations were not widely available and no other practical methods existed. Graphical inspection using statistical and geographical displays to isolate sets of background data is far better suited for estimating the range of background variation and thresholds, action levels (e.g., maximum admissible concentrations--MAC values) or clean-up goals in environmental legislation.

Journal Article↗

PubMed2005

Distinguishing between natural and anthropogenic sources for elements in the environment: regional geochemical surveys versus enrichment factors.

High element enrichment factors (EFs) are commonly used in the literature to support the hypothesis that a particular suite of elements is of anthropogenic origin. Real-world examples of regional geochemical surveys demonstrate that EFs can be high or low due to a multitude of reasons, of which contamination is but one. This applies to EFs calculated relative to either the crust or some local background (e.g., a deeper soil layer). Results from local studies near industrial centres showing high (and pollution-related) EFs cannot be generalised over large areas or for sample sites far removed (i.e., more than some tens of kilometers) from a likely pollution source. Regional-scale geochemical mapping, on the other hand, facilitates the reliable estimation of the influence of contamination on the measured element concentrations. EFs are strongly influenced by, among other factors, biogeochemical processes that redistribute chemical elements between environmental compartments at the Earth's surface. Using EFs to detect or 'prove' human influence on element cycles in remote areas should be avoided because, in most cases, high EFs cannot conclusively demonstrate, nor even suggest, such influence.

Earth, Planet↗

PubMed2004

Setting action levels for drinking water: are we protecting our health or our economy (or our backs!)?

Clean and healthy drinking water is important for life. Drinking water can be drawn from streams, lakes and rivers, directly collected (and stored) from rain, acquired by desalination of ocean water and melting of ice or it can be extracted from groundwater resources. Groundwater may reach the earth's surface in the form of springs or can be extracted via dug or drilled wells; it also contributes significantly to river baseflow. Different water quality issues have to be faced when utilising these different water resources. Some of these are at present largely neglected in water quality regulations. This paper focuses on the inorganic chemical quality of natural groundwater. Possible health effects, the problems of setting meaningful action levels or maximum admissible concentrations (MAC-values) for drinking water, and potential shortcomings in current legislation are discussed. An approach to setting action levels based on transparency, toxicological risk assessment, completeness, and identifiable responsibility is suggested.

Drinking↗

PubMed2003

Drinking water quality in the Ethiopian section of the East African Rift Valley I--data and health aspects.

Drinking water samples were collected throughout the Ethiopian part of the Rift Valley, separated into water drawn from deep wells (deeper than 60 m), shallow wells (<60 m deep), hot springs (T>36 degrees C), springs (T<32 degrees C) and rivers. A total of 138 samples were analysed for 70 parameters (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Cl, Co, Cr, Cs, Cu, Dy, Er, Eu, F, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, In, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, NO(2), NO(3), Pb, Pr, Rb, Sb, Se, Si, Sm, Sn, SO(4), Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, temperature, pH, conductivity and alkalinity) with ion chromatography (anions), spectrometry (ICP-OES and ICP-MS, cations) and parameter-specific (e.g. titration) techniques. In terms of European water directives and WHO guidelines, 86% of all wells yield water that fails to pass the quality standards set for drinking water. The most problematic element is fluoride (F), for which 33% of all samples returned values above 1.5 mg/l and up to 11.6 mg/l. The incidence of dental and skeletal fluorosis is well documented in the Rift Valley. Another problematic element may be uranium (U)-47% of all wells yield water with concentrations above the newly suggested WHO maximum acceptable concentration (MAC) of 2 microg/l. Fortunately, only 7% of the collected samples are above the 10 microg/l EU-MAC for As in drinking water.

Ethiopia↗

PubMed2003

High-fluoride drinking water. A health problem in the Ethiopian Rift Valley 1. Assessment of lateritic soils as defluoridating agents.

PURPOSE: High-fluoride drinking water represents a health hazard to millions of people, not least in the East African Rift Valley. The aim of the present project was to establish a simple method for removing excessive fluoride from water. MATERIAL AND METHODS: Based on geological maps and previous experience, 22 soil samples were selected in mountainous areas in central Ethiopia. Two experiments were performed: 1. After sieving and drying, two portions of 50 g were prepared from each soil and subsequently mixed with solutions of NaF (500 mL). Aliquots (5 mL) of the solutions were taken at pre-set intervals of 1 hour to 30 days for fluoride analysis--using an F-selective electrode. 2. After the termination of the 30-days test, liquids were decanted and the two soil samples that had most effectively removed fluoride from the NaF solutions were dried, and subsequently exposed to 500 mL aqua destillata. The possible F-release into the distilled water was assessed regularly. RESULTS: Great variations in fluoride binding patterns were observed in the different soils. The percent change in F-concentration in the solutions, as compared to the original absolute value(F-), varied: at 1 hour from a decrease of 58% to an actual increase of 7.7%, while--at 30 days--all soil samples had caused a decrease in the F-concentration, varying from 0.5% to 98.5%. Only minute amounts of fluoride would leach from the fluoride-enriched soils. CONCLUSION: Lateritic soils may remove excessive fluoride from drinking water. Methods for practical application of this principle should be tested at household level.

Desiccation↗