Lars Nyberg

Spatial variability of soil water content in the covered catchment at Gårdsjön, Sweden

The spatial variability of soil water content was investigated for a 6300 m2 covered catchment on the Swedish west coast. The catchment podzol soil is developed in a sandy—silty till with a mean depth of 43 cm and the dominant vegetation is Norway spruce. The acid precipitation is removed by a plastic roof and replaced with lake water irrigated under the tree canopies. On two occasions, in April and May 1993, TDR measurements were made at 57–73 points in the catchment using 15 and 30 cm long vertically installed probes. The water content pattern at the two dates, which occurred during a relatively dry period, were similar. The range of water content was large, from 5 to 60%. In May 1993 measurements also were made in areas of 10 × 10 m, 1 × 1 m and 0·2 × 0·2 m. The range and standard deviation for the 10 × 10 m area, which apart from a small-scale variability in soil hydraulic properties and fine root distribution also had a heterogeneous micro- and macro-topography, was similar to the range and standard deviation for the catchment. The 1 × 1 m and 0·2 × 0·2 m areas had considerably lower variability. Semi-variogram models for the water content had a range of influence of about 20 m. If data were paired in the east-–west direction the semi-variance reflected the topography of the central valley and had a maximum for data pairs with internal distances of 20–40 m. The correlation between soil water content and topographic index, especially when averaged for the eight topographically homogeneous subareas, indicated the macro-topography as the cause of a large part of the water content variability.

Transit Times for Water in a Small Till Catchment from a Step Shift in the Oxygen 18 Content of the Water Input

Transit times for water in a small till catchment from a step shift in the oxygen-18 content of the water input

Advances in understanding the podzolization process resulting from a multidisciplinary study of three coniferous forest soils in the Nordic Countries

Advances in understanding the podzolisation process resulting from a multidisciplinary study at three coniferous forest soils in the Nordic countries

Distribution and mobilization of Al, Fe and Si in three podzolic soil profiles in relation to the humus layer.

Distribution and mobilization of Al, Fe and Si in three podzolic soil profiles in relation to the humus layer

Water transit times and flow paths from two line injections of 3H and 36Cl in a microcatchment at Gårdsjön, Sweden

To investigate groundwater transit times and flow paths in shallow till soil, within an acidification study at Gardsjon, Sweden, two line injections of Cl-36 and H-3 Were made in groundwater during ...

Water flow path interactions with soil hydraulic properties in till soil at Gårdsjön, Sweden

In 1989, in a hydrological research programme within a deacidification project in the Gardsjon area in southwest Sweden, flow paths and residence times of soil water and groundwater in microcatchments were examined to support the interpretation of the hydrochemical changes. Saturated hydraulic conductivity and soil water retention were analysed on more than 100 cylinder samples. The catchments have shallow sandy-silty till soil with a mean depth in the main catchment of 43 cm. Porosity of the mineral soil in the main catchment was high and ranged from 38 to 85%. The samples from the B-horizon had generally higher porosity. Porosity and the content of organic matter were correlated. The soil water retention was relatively high at all tensions, likely owing to the high content of organic matter. Dissolved organic substances were most probably transported from the shallow soil on the steep sides of the catchment down to the valley where it precipitated. The high porosities could be a consequence of long-term weathering, provided that the organic substances present have increased the leaching of the weathering products. Measured values of saturated hydraulic conductivity were close to log-normally distributed with a mean for all samples of 3 × 10−5 m s−1. There was a significant increase in conductivity toward the ground surface with the mean conductivity of the samples in the uppermost 10 cm of the mineral soil of 4 × 10−5 m s−1, which was about 13 times higher than the conductivity of 3 × 10−6 m s−1 at 1 m depth. From the relationship between runoff at the catchment outlet and groundwater levels, the conductivity was estimated to be 15–200 times higher in the upper soil layer than in the deeper ones. In one profile, 44–64% of the yearly lateral flow was estimated to occur above 30 cm depth. The conductivity was correlated with the content of drainable water, which indicated the importance of the largest pores for the saturated hydraulic conductivity.

Controlling mechanisms of aluminium in soil solution - an evaluation of 180 podzolic forest soils

To monitor the level of soil acidification in the county of Värmland in the middle west of Sweden 180 podzolic forest soils were investigated. Soil solutions from four horizons were obtained by centrifugation and the soil was sampled for a determination of the exchangeable pool by extraction. The concentrations of inorganic Al and its fraction of the total Al in solution were greater in the south of the county (up to 50%). The factors influencing the total Al and free inorganic Al3+ in the soil solutions were evaluated. Saturation indices (SI) for five different mineral phases were calculated but none implied equilibrium conditions. The relationships between pAl3+ and pH (in the pH range 4-6.2) gave slopes of about 1, which indicated that ion exchange/complexation reactions may be important for determining the Al3+ concentration in the B and C horizons. In the E horizon solutions complexation with soluble organic acids seemed to be the major factor which influenced the Al3+ activity. The influence of organic matter on Al solubility was supported by partial least square (PLS) regressions.

Effects of acidification and its mitigation with lime and wood ash on forest soil processes in southern Sweden. A joint multidisciplinary study

A joint multidisciplinary investigation was undertaken to studythe effects of lime and wood ash applications on two Norway spruce forest Spodosolic soils. The two sites, typical for southern Sweden, were treated in 1994 with either 3.25 t ha-1 dolomite or 4.28 t ha-1 wood ash (Horröd site) or in 1984 with either 3.45 or 8.75 t ha-1 dolomite (Hasslöv site). Both sites show signs of acidification by atmospheric anthropogenic deposition and possessed low soil pH(4.3) and high concentrations of inorganic Al (35 μM) in theupper illuvial soil solution. The prevailing soil conditions indicated perturbed soil processes. Following treatment with lime or wood ash, the soil conditions were dramatically altered. Cation exchange capacity (CEC) and base saturation (BS) was considerable increased after addition. Four years after application most of the added Ca and Mg was still present in the mor layer. Fifteen years after application,Mg in particular, became integrated deeper in the soil profile with a greater proportion lost by leaching incomparison to Ca. The concentrations of these ions were greatestin the mor layer soil solutions and Mg had higher mobility givinghigher concentrations also deeper in the profile. Four years after treatment, the application of wood ash and limeresulted in lower pH values and higher inorganic Al in mineral subsoil solutions compared to the untreated soil. We hypothesize that this was probably due to an increased flow of hydrogen ionsfrom the upper soil as a result of displacement by Ca and Mg ionsin the enlarged exchangeable pool. In contrast, fifteen years after lime and wood ash application, the mineral subsoil horizonspossessed a higher pH and lower soil solution Al content than theuntreated plots.Liming promoted soil microbial activity increasing soil respiration 10 to 36%. This is in the same range as net carbon exchange for forests in northern Sweden and could potentially have a climatological impact. The turnover of low molecularweight organic acids (LMWOA) by the soil microbial biomass werecalculated to contribute 6 to 20% to this CO2 evolution.At Horröd, citrate and fumarate were the predominant LMWOAs with lowest concentrations found in the treated areas. In contrast, at the Hasslöv site, propionate and malonate were the most abundant LMWOAs. Higher microbial activity in the upper soil horizons was also theprobable cause of the considerably higher DOC concentrations observed in the soil solution of ash and lime treated areas. Thelime-induced increase in DOC levels at Hasslöv could be attributed to increases in the 3–10 kDa hydrophobic size fraction. Liming also promoted nitrification with high liming doses leading to extreme concentrations of NO3- (1 mM) in soil solution.At Hasslöv the community of mycorrhizal fungi was dramatically changed by the addition of lime, with only four of 24 species recorded being common to both control and treated areas.Many of the observed effects of lime and ash treatment can be viewed as negative in terms of forest sustainability. After fouryears of treatment, there was a decrease in the pH of the soil solution and higher concentrations of inorganic Al and DOC. Increased organic matter turnover, nitrification and NO3-leakage were found at Hasslöv. Considering that the weathering rate and the mineral nutrient uptake by trees is mostprobably governed by mycorrhizal hyphae etchingmineral grains in the soil, it is important to maintain this ability of the mycorrhizal fungi. The lime and ash-induced changed mycorrhizal community structure may significantly affect this capability. In light of this investigation and others, as reviewed by Lundström et al. (2003), the implications ofliming on forest health are multifaceted with complex relationships occurring over both space and time.

Importance of hydrology in the reversal of acidification in till soils, Gårdsjön, Sweden

In order to determine, experimentally, the rate at which surface water quality recovers after acid deposition is reduced, a roof was built over a small catchment near Lake Gardsjon, southwest Sweden. By irrigating the catchment with chemically adjusted water, the input of S and N is reduced by at least 90%. Previous hydrological research on catchments similar to that used in the roof experiment suggested that storm runoff from the catchment is concentrated in surface-near soil layers, temporarily saturated when the water table has risen in response to rainfall. If so, it is suggested that the improvements in water quality using the roof catchment will appear first in storm runoff, because the spate-specific flow pathways will be flushed by the large throughput of the non-acidic irrigation water. The hydrological basis of this suggestion was investigated using hydrometric observations and tracer studies. Laboratory analysis of ~100 soil samples gave mean values of the saturated hydraulic conductivity of 1 × 10−4 m/s in the uppermost 20 cm of the soil layer, decreasing to 6 × 10−6 m/s in the 20 cm closest to bedrock. The variation in hydraulic conductivity roughly agreed with the one inferred from the observed relation between groundwater level and catchment runoff. A preliminary tracer experiment with injected 3H and 36Cl, conducted during a very wet period, showed particle velocities of >1 m/h in the soil. This was significantly higher than velocities estimated from hydrometric observations, being ~0.1 m/h in the A horizon and ~0.01 m/h in the less conductive B and C horizons. The greater particle velocity indicated by the tracer experiment suggested that much of the flow was concentrated in a small fraction of the pore space. The replacement of the pre-irrigation water in the catchment by irrigation water could be investigated by using 18O, because the 18O content of the irrigated water differed from that of the groundwater and soil water before the irrigation. The 18O data showed that after six months of irrigation, about one fourth of the baseflow was new water.

Selective determinations of amines and quaternary ammonium compounds as ion pairs with methyl orange by an automated method applicable to single dose analysis.

Aliphatic amines and quaternary ammonium compounds can be determined photometrically after extraction as ion pairs with methyl orange. Extraction conditions are calculated from constants for the extraction procedure and side‐reactions. Methods for the selective determination of ammonium ions of different degrees of substitution are given. Quaternary ammonium ions are isolated by extraction at pH 12. The amines are extracted as ion pairs at pH 4.6 and selective determinations can be made after primary and secondary amines are masked by acetylation and primary amines by coupling with salicylic aldehyde. An automated application of the method on a Technicon AutoAnalyzer is presented. A complete analysis of a sample containing the four kinds of ammonium ions requires four separate runnings. The same basic manifold is used for all the runnings with some rearrangements for the masking procedures. The method has been tested on benzhexol, diethylpropion, dodecylamine, emepronium, N‐hydroxyethylpromethazine, promethazine and protriptyline. Recoveries of about 100% with a relative variation of 1–2% were obtained.