Bjørn Frengstad

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.

Comparison of the element composition in several plant species and their substrate from a 1 500 000-km2 area in Northern Europe

Leaves of 9 different plant species (terrestrial moss represented by: Hylocomium splendens and Pleurozium schreberi; and 7 species of vascular plants: blueberry, Vaccinium myrtillus; cowberry, Vaccinium titis-idaea; crowberry, Empetrum nigrum; birch, Betula pubescens; willow, Salix spp.; pine, Pinus sylvestris and spruce, Picea abies) have been collected from up to 9 catchments (size 14-50 km2) spread over a 1500000 km2 area in Northern Europe. Soil samples were taken of the O-horizon and of the C-horizon at each plant sample site. All samples were analysed for 38 elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Th, Tl, U, V, Y, Zn and Zr) by ICP-MS, ICP-AES or CV-AAS (for Hg-analysis) techniques. The concentrations of some elements vary significantly between different plants (e.g. Cd, V, Co, Pb, Ba and Y). Other elements show surprisingly similar levels in all plants (e.g. Rb, S, Cu, K, Ca, P and Mg). Each group of plants (moss, shrubs, deciduous and conifers) shows a common behaviour for some elements. Each plant accumulates or excludes some selected elements. Compared to the C-horizon, a number of elements (S, K, B, Ca, P and Mn) are clearly enriched in plants. Elements showing very low plant/C-horizon ratios (e.g. Zr, Th, U, Y, Fe, Li and Al) can be used as an indicator of minerogenic dust. The plant/O-horizon and O-horizon/C-horizon ratios show that some elements are accumulated in the O-horizon (e.g. Pb, Bi, As, Ag, Sb). Airborne organic material attached to the leaves can thus, result in high values of these elements without any pollution source.

Variation of 66 elements in European bottled mineral waters

Fifty-six bottled mineral waters bought at random all over Europe were analysed for 66 chemical elements by ICP-AES, ICP-MS and IC-techniques. Results show that there is a wide spread in the chemical composition of mineral waters. The EEC drinking water safeguard values for chemical constituents do not apply to mineral water, although mineral water is increasingly used for general drinking water purposes. Only 15 of the randomly selected 56 mineral waters would fulfil the drinking water regulations for all parameters where action levels are defined. Differences in chemical composition observed between countries or regions are due to geological environment and to different taste or local regulations of what is mineral water. There are indications that element concentrations for some unwanted constituents (e.g. Pb) are higher in waters sold in glass bottles than in those in plastic bottles. Some elements show a clear regional dependency. Studying the large natural variation in concentration for many of the 66 studied elements it becomes clear that we know little about the natural variation of element concentration in water and the health effects of most elements in drinking water.

The chemistry of Norwegian groundwaters: I. The distribution of radon, major and minor elements in 1604 crystalline bedrock groundwaters

A quality-controlled hydrogeochemical dataset of 1604 groundwater samples from Norwegian crystalline bedrock aquifers has been obtained and subject to analyses of radon (scintillation counting), major and minor elements (ion chromatography and ICP-AES), pH and alkalinity. Cumulative probability curves may be constructed to assess the risk of given parameters violating drinking water norms. Parameters such as radon and fluoride show clear lithological correlation, occurring at high concentrations in granites and low concentrations in anorthosites. Other parameters exhibit a lower degree of correlation with aquifer geochemistry (e.g. pH, major ions) and are likely to be governed by more universal thermodynamic equilibria (the calcium carbonate system) and kinetic factors. On a national basis 13.9% of the bedrock groundwaters exceed the recommended action level for radon, while 16.1% exceed the drinking water norm for fluoride. Considering pH, sodium, radon and fluoride together, 29.9% of all wells violate drinking water maximum concentrations for one or more of these parameters.

The chemistry of Norwegian groundwaters: IV. The Ph-dependence of element concentrations in crystalline bedrock groundwaters

A total of 1604 samples of crystalline bedrock groundwaters in Norway have been analysed for pH, major and minor elements. A subset of 476 samples were also analysed for a wide range of trace elements by ICP-MS. The pH of the samples ranges from 5.4 to 9.8, with a predominance of pH values between 8.0 and 8.2. The data-set is divided into five 20-percentile groups according to increasing pH. The concentrations of 60 elements are then displayed as box-plots for each pH group. A line through the five medians yields a visual demonstration of the relationship with, and sensitivity to, pH variations for concentrations of each element. Twelve characteristic trends are distinguishable, from which some of the main hydrogeochemical processes related to pH and groundwater evolution can be inferred.

Insights into the reliability of different thermal conductivity measurement techniques: a thermo-geological study in Mære (Norway)

Thermal response tests (TRTs) are used to measure the effective thermal conductivity in boreholes. The results serve as a basis for the dimensioning of commercial ground-source heat pump installations with closed loop systems. The study evaluated the reliability of TRTs performed in winter by comparing two TRTs carried out under very different winter weather conditions. A third TRT elucidated the influence of convection in wells with a higher heat input. Rock cores were analysed for quartz content and these results and the laboratory-measured thermal conductivity data were compared with the TRT results. This highlighted the importance of the distribution and orientation of minerals in the rock, and that a high quartz content does not necessarily give high thermal conductivity values. It is concluded that winter TRTs give useful results if additional temperature loggers are installed in anticipated fracture zones to detect groundwater flow and to survey the effect of infiltrating water.RésuméDes tests de réponse thermique (TRT) sont utilisés pour mesurer la conductivité thermique effective dans les forages. Les résultats servent au dimensionnement d’installations commerciales géothermiques de pompes à chaleur. Cette étude a évalué la fiabilité de ces tests réalisés en hiver, par comparaison avec deux essais réalisés sous des conditions climatiques très différentes. Un troisième essai a permis de comprendre l’influence de la convection dans les puits avec un apport de chaleur plus important. Des carottes de roche ont été analysées par rapport à leur teneur en quartz. Ces résultats et les mesures de conductivité thermique obtenues au laboratoire ont été comparés avec les résultats de tests TRT. Ceci a mis en lumière l’importance de la répartition et de l’orientation des minéraux dans la roche, et le fait qu’une forte teneur en quartz ne donne pas nécessairement des valeurs fortes de conductivité thermique. On conclut que les tests TRT réalisés en hiver donnent des résultats utiles à condition que des enregistreurs de température supplémentaires soient installés dans les zones de fracture prévues afin de détecter des arrivées d’eau souterraine et analyser les effets des eaux d’infiltration.

Alkaline mine drainage from metal sulphide and coal mines: examples from Svalbard and Siberia

Abstract Not all water from coal or metal mines is acidic. Circum-neutral or alkaline mine drainage may be due to: (i) a low content of sulphide minerals; (ii) the presence of monosulphides rather than pyrite or marcasite; (iii) a large pyrite grain-size limiting oxidation rate; (iv) neutralization of acid by carbonate or basic silicate minerals; (v) engineering factors (introduction of lime dust for explosion prevention; cement or rock flour during construction works); (vi) neutralization of acid by naturally highly alkaline groundwaters; (vii) circulating water not coming into effective contact with sulphide minerals; and (viii) oxygen not coming into direct contact with sulphide minerals or influent water being highly reducing.

Total sulphur in leaves of several plant species from nine catchments within a 1 500 000 km2 area in northern Europe: local vs. regional variability

Leaves of up to eleven different plant species (terrestrial moss: Hylocomium splendens and Pleurozium schreberi; blueberry: Vaccinium myrtillus and Vaccinium uliginosum; cowberry: Vaccinium vitis-idaea; crowberry: Empetrum nigrum; birch: Betula pubescens and Betula nana; willow: Salix spp.; pine: Pinus sylvestris; and spruce: Picea abies) have been collected from up to nine catchments (size 14–50 km2) spread over a 1 500 000 km2 area in northern Europe and analysed for ‘total’ (digestion by 16M HNO3) sulphur concentrations. Soil samples were taken of the O- and C-horizon at each plant sample site. The soil samples were analysed for ‘total’ (digestion by 16M HNO3 for O-horizon, aqua regia for C-horizon) and ‘soluble’ (ammonium acetate extraction buffered at pH 4.5, O-horizon only) S concentrations. The overall median S concentration for all plants is 1290 mg kg−1. The median S concentration is 965 mg kg−1 in moss; 990 mg kg−1 in conifers; 1490 mg kg−1 in shrubs; and 1900 mg kg−1 in deciduous trees. Total S concentrations in the leaves of the 11 plant species are very different within and between the catchments. Compared to the total regional variance, the local variance within just one catchment is very high. One of the nine catchments was located directly adjacent (5–10 km S) to the nickel smelter and refinery at Monchegorsk, Kola Peninsula, Russia, one of the largest SO2 (and metal) emitters in Europe. Only spruce needles returned significantly higher S concentrations (by a factor of 2) in all samples collected near Monchegorsk. Otherwise pollution is reflected in a higher variance rather than in high concentrations. Willow leaves show by far the highest total S concentrations. They are, however, not related to pollution but were observed in the catchment nearest to the coast of the Barents Sea. The measured S concentrations in the leaves do not correlate well either with ‘available’ or total S in the soils. Several different pathways must be considered for leaf uptake of S in all plants. The important role of S as a major plant nutrient and the consequently high background concentrations and variations prohibit the use of leaves as reliable indicators of SO2 pollution levels in air. It is not possible to establish general ‘background’ S concentrations in plant leaves for a very large area.

Carbon-13 in groundwater from English and Norwegian crystalline rock aquifers: a tool for deducing the origin of alkalinity?

The 13C signature is evaluated for various environmental compartments (vegetation, soils, soil gas, rock and groundwater) for three crystalline rock terrains in England and Norway. The data are used to evaluate the extent to which stable carbon isotopic data can be applied to deduce whether the alkalinity in crystalline bedrock groundwaters has its origin in hydrolysis of carbonate or silicate minerals by CO2. The resolution of this issue has profound implications for the role of weathering of crystalline rocks as a global sink for CO2. In the investigated English terrain (Isles of Scilly), groundwaters are hydrochemically immature and DIC is predominantly in the form of carbonic acid with a soil gas signature. In the Norwegian terrains, the evidence is not conclusive but is consistent with a significant fraction of the groundwater DIC being derived from silicate hydrolysis by CO2. A combined consideration of pH, alkalinity and carbon isotope data, plotted alongside theoretical evolutionary pathways on bivariate diagrams, strongly suggests real evolutionary pathways are likely to be hybrid, potentially involving both open and closed CO2 conditions.