Dag Olav Andersen

VARIATIONS IN CONCENTRATIONS OF AQUEOUS ALUMINIUM AND OTHER CHEMICAL SPECIES DURING HYDROLOGICAL EPISODES AT BIRKENES, SOUTHERNMOST NORWAY

Abstract Concentrations of H + , aluminium species, total fluoride, silica, TOC, and major cations and anions were measured in stream- and soil water in the Birkenes catchment during base-flow and high discharge hydrological episodes from 1984 to 1986. Snow and meltwater were also sampled before and during the spring snowmelt seasons. During all the rainfall and snowmelt hydrological events for the five field periods analysed, the H + concentration increased with flow, whereas inorganic monomeric aluminium, Al i (including Al 3+ ), increased with flow only during episodes preceded by relatively low flow periods; during subsequent events Al i remained nearly constant or even decreased. Concentrations of Al i and H + in soil water sampled under saturated conditions were generally stable over time compared to the variations for these species in streamwater. The considerable fluctuations observed for chloride Cl − and sulphate SO 2− 4 concentrations illustrated that displacement of soil water occurred. The results confirm the importance of hydrological factors in determining episodic aluminium response. Large variations in the saturation indices show that equilibrium with either Al(OH) 3 (gibbsite) or Al 2 Si 2 O 5 (OH) 4 (kaolinite, halloysite) cannot control aluminium concentrations in streamwater at Birkenes; the same is true for Al(OH)SO 4 (jurbanite) although the saturation index for this mineral is less variable. Most probably, different controlling mechanisms predominate in the different soil layers, producing different chemical signatures which are picked up in the stream to varying degrees depending on hydrological conditions.

Key site variables governing the functional characteristics of Dissolved Natural Organic Matter (DNOM) in Nordic forested catchments

Abstract.The objective of this study was to extract and evaluate key catchment characteristics explaining the main variation in properties of dissolved natural organic matter (DNOM) in surface waters draining each catchment. A number of classical and sophisticated DNOM characterisation methodologies were used for this purpose. The explanatory capability of site characteristics on the variation in descriptors of DNOM, including elemental analysis (EA), DOC fractionation, SEC, CZE, CGE, UV/Vis- and FTIR spectra, FES, TLS, ESR, ESI/MS, 13C-CPMAS-NMR, potentiometric pH titration as well as functional characteristics such as biodegradability, and the response of macrophyte and PAH partitioning coefficients were evaluated. The sampling sites were all natural, coniferous, heathery-forested catchments with bogs, forming a climatic, anthropogenic deposition and proportional biotope cover gradient.Correlations to the main principal components, as well as a correlation matrix, singled out total S-deposition as the key explanatory site parameter, accounting for most of the variation in DNOM descriptors. Other significant factors were H+ concentration, length of growing season, biotope coverage (i.e., peatland/ or lake/watershed ratio), site elevation and TOC concentration. Total sulphur (S) deposition was strongly negatively correlated to the molecular weight, aromaticity, carboxylic acidity and sorption capacity of PAH. A greater proportion of lake and Histosol biotopes of the sampling sites were reflected in a greater aliphatic character of the DNOM. PCA clustering of samples from the same site in spring and fall showed a basic site-specific DNOM quality and a weak season effect. The Hasse diagram technique (a method of partial order theory) was used to show, for instance, how the relative Histosol coverage may determine NOM quality and, in turn, how this coincides with high macrophyte response.

NATURE OF NATURAL ORGANIC MATTER (NOM) IN ACIDIFIED AND LIMED SURFACE WATERS

Natural organic matter (NOM) was isolated by reverse osmosis (RO) from the two inlet brooks and the outlet of Lake Terjevann with estimated recoveries of 85-90%. The lake has been receiving liming treatments since 1980 due to the acidic drainage from the catchments. High- performance size exclusion chromatography (HPSEC) analyses of the RO samples and of ultrafiltered fractions indicate that there are five main size fractions of carbon with molecular weights between 410- 1170 Da in all three samples. However, the molecular weight distributions diAer significantly in that the outlet sample have lower proportions of larger molecular weight NOM than do the inlets. Studies of spectral absorption coeAcients at 254 nm support this molecular size distribution. Absorption coeAcients of the samples at both 254 and 410 nm decrease with decreasing molecular weight so that the ratio E2/E4 increases with decreasing molecular weight. This trend appears independent of pH changes and especially eAects the absorption coeAcients of the higher molecular weight NOM. Studies of C:N ratios of the RO samples and of ultrafiltered fractions indicate that the outlet RO sample and that the lower molecular weight NOM are enriched in nitrogen. Supported by studies of spectral absorption coeAcients and C:N ratios of the total RO samples and ultrafiltered fractions and eAects of pH changes on the ultrafiltered fractions, it is hypothesized that in-lake processes are removing larger molecular weight NOM. This is possibly an eAect of the liming which increase pH and calcium(II) concentrations in the lake water coinciding with hydrolysis and precipitation of aluminium(III) and iron(III). # 1999 Elsevier Science Ltd. All rights reserved

Sediment content of metals before and after lake water liming

Long-term liming (1980-1991) of an acidified lake (Lake Terjevann) in the southernmost part of Norway, show an increased accumulation of Al, Fe, Mn, Cd, Cu, Ni, Zn in the sediments which clearly corresponds with the liming history. The increased precipitation of Al, Fe and Mn are ascribed to extended formation of oxyhydroxides due to increased pH after introduction of the lime. Statistically significant correlations indicate that Cu, Ni and Zn are coprecipitated with both Al and Fe oxyhydroxides while Cd is coprecipitated primarily with Fe oxyhydroxides both previous to and after lake water liming.

Comparison of high-pressure liquid chromatography (HPLC) and Griess reagent-spectroscopic methods for the measurement of nitrate in serum from healthy individuals in the Nordic countries

OBJECTIVES Bioavailability of NO can be estimated by measuring the concentration of nitrate (NO(3)) in serum. However, the methods used for the measurement NO(3) in plasma or serum show a great degree of variation. Therefore, we compared two analytical methods for the measurement of NO(3) in serum. DESIGN AND METHODS The concentration of NO(3) in 600 serum samples collected from healthy individuals was determined by the HPLC and by the Griess reagent-spectroscopic method. RESULTS The concentration of NO(3) in the samples was 29.4+/-16.1 micromol/L and 26.2+/-14.0 micromol/L (mean+/-SD) measured by HPLC and Griess reagent-spectroscopic method respectively (p<0.0001). We detected a significant correlation between the two methods (R=0.81, p<0.0001). CONCLUSIONS A significant correlation between the two methods may suggest that either method can be used for the measurement of NO(3) in serum, however the Griess reagent-spectroscopic method measures lower concentrations of NO(3) than the HPLC method.

Natural organic matter (NOM) in a limed lake and its tributaries

The chemistry of a limed lake and its main tributaries were studied for 3 years (1992-94) with an emphasis on natural organic matter (NOM). Increased transparency and decreased water colour indicated a general reduction of NOM in the lake. Increased A(254 nm)/A(410 nm) ratios in the epilimnion during summer and early autumn suggested degradation of higher molecular size organic matter into low molecular size NOM. Increase in ammonium and dissolved inorganic carbon concentrations in the lake was possibly due to the NOM degradation. Using budget calculations and the literature values, photodegradation and microbial activity were estimated to be the main mechanisms of the NOM removal. These mechanisms accounted for about 30-35% and 60-65% of the total loss of organic matter, respectively, in the summer and early autumn period. Low sedimentation rates indicate that co-precipitation of organic matter with calcium, aluminium and/or iron was of minor importance in these seasons.

In vivo effect of N-ethylmaleimide (NEM) on the measurement of nitrate in plasma.

BACKGROUND Bioavailability of nitric oxide in the body may be estimated by measuring the concentration of nitrate in plasma. However, it has not been reported whether sequestering of aminothiols in plasma affects the concentration of nitrate in the samples. OBJECTIVE N-ethylmaleimide (NEM) sequesters aminothiols in plasma therefore we tested the in vivo effect of NEM on the concentration nitrate in plasma. SUBJECTS AND METHODS Blood samples were collected from 56 healthy subjects in EDTA vials, EDTA vials containing PBS (pH7.4) and EDTA vials containing NEM dissolved in PBS. Nonparametric statistical tests were used to study the effect of NEM on the concentration of nitrate in plasma measured by the Griess reagent assay and by an HPLC method. RESULTS The concentration of nitrate in plasma containing NEM dissolved in PBS was lower than plasma containing PBS and plasma without any reagent measured by the Griess reagent assay (p<0.001 and p<0.001). Similarly, the concentration of nitrate in plasma containing NEM measured by the Griess reagent assay was significantly lower than nitrate concentration in plasma measured by the HPLC method (p<0.001). CONCLUSION Our findings suggest that plasma, which contains NEM, may not be suitable for the measurement of nitrate by the Griess reagent assay.

Impacts of warm winters and extreme rainstorms on the base consumption in a limed lake, southern Norway

The chemical composition of a limed lake, the two main inlets and the outlet was monitored during a period of 3 years. The winters of 1991-1992 and 1992-1993 were unusually warm while the winter of 1993-1994 was more normal. The lake surface water was wind exposed in the warm winters and as a consequence of frequent turnovers the acid input from the catchment mixed with the whole lake water body. In the winter of 1993-1994, the lake was ice-covered for approximately 4 months. During this period the drainage water from the catchment flowed to the outlet of the lake in the upper 2-3 m of the water column and only some of the acid input was neutralised. This is compared to a complete neutralisation in the winter of 1992-1993. The in-lake loss of alkalinity during this warm winter was approximately 29 microeq/l (November-June) compared to approximately 7 microeq/l lakewater in 1993-1994. Acid drainage from the catchment induced by an extraordinary rainstorm with heavy sea-salt deposition contributed to the in-lake alkalinity consumption in spring 1993. As winter temperatures above 0 degrees C and more frequent rainstorms may be common due to expected global warming, future increased lime consumption in-lakes may be projected in acidified areas as southern Norway.

Dissolved oxygen concentration in stream waters draining the catchment of Lake Terjevann, SE Norway

Aerobic soil respiration involves the breakdown of complex carbon molecules. Oxygen consumed in this process then influences the oxygen concentration of percolating rainwater. The respiration rate depends on factors such as soil depth, organic matter content, oxygen supply, soil moisture and temperature (WHITE 1987), indicating that seasonal variations in dissolved oxygen are likely to occur in drainage water from catchments. As little was found in limnological textbooks (Hl.JCCHINSON 1975, WETZEL 1975, COLE 1979) regarding such seasonality, dissolved oxygen was included as an element in an integrated study of drainage water from rwo acidified catchments and the adjacent limed lake, Lake Terjevann. Study site