scholarly journals Linking groundwater travel times to stream chemistry, isotopic composition and catchment characteristics

2020 ◽  
Author(s):  
Elin Jutebring Sterte ◽  
Fredrik Lidman ◽  
Emma Lindborg ◽  
Ylva Sjöberg ◽  
Hjalmar Laudon
Keyword(s):  
Travel Time ◽  
Stream Water ◽  
Base Cations ◽  
Base Cation ◽  
Isotopic Signature ◽  
Stream Chemistry ◽  
Travel Times ◽  
Underlying Assumption ◽  
Tracking Model

Abstract. Understanding travel times of rain and snowmelt inputs transported through the subsurface environment to recipient surface waters is critical in many hydrological and biogeochemical investigations. In this study, a particle tracking model approach in Mike SHE was used to investigating the travel time of stream groundwater input to 14 partly nested, long-term monitored boreal sub-catchments. Based on previous studies in the area, we hypothesized that the main factor controlling groundwater travel times was catchment size. The modeled mean travel time (MTT) in the different sub-catchments ranged between 0.5 years and 3.6 years. Estimated MTTs were tested against the observed long-term winter isotopic signature (δ2H, δ18O) and chemistry (base cation concentration and pH) of the stream water. The underlying assumption was that older water would have an isotopic signature that resembles the long-term average precipitation input, while seasonal variations would be more apparent in catchments with younger water. Similarly, it was assumed that older water would be more affected by weathering, resulting in higher concentrations of base cations and higher pH. 10-year average winter values for stream chemistry were used for each sub-catchment. We found significant correlations between the estimated travel times and average water isotope signature (r = 0.80, p 

scholarly journals How catchment characteristics influence hydrological pathways and travel times in a boreal landscape

2021 ◽  
Vol 25 (4) ◽  
pp. 2133-2158
Author(s):  
Elin Jutebring Sterte ◽  
Fredrik Lidman ◽  
Emma Lindborg ◽  
Ylva Sjöberg ◽  
Hjalmar Laudon
Keyword(s):  
Groundwater Recharge ◽  
Travel Time ◽  
Overland Flow ◽  
Geometric Mean ◽  
Base Cation ◽  
Travel Times ◽  
Soil Frost ◽  
Landscape Type ◽  
Hydrological Responses ◽  
Tracking Model

Abstract. Understanding travel times and hydrological pathways of rain and snowmelt water transported through the landscape to recipient surface waters is critical in many hydrological and biogeochemical investigations. In this study, a particle-tracking model approach in Mike SHE was used to investigate the pathway and its associated travel time of water in 14 partly nested, long-term monitored boreal sub-catchments of the Krycklan catchment (0.12–68 km2). This region is characterized by long and snow-rich winters with little groundwater recharge and highly dynamic runoff during spring snowmelt. The geometric mean of the annual travel time distribution (MTTgeo) for the studied sub-catchments varied from 0.8 to 2.7 years. The variations were related to the different landscape types and their varying hydrological responses during different seasons. Winter MTTgeo ranged from 1.2 to 7.7 years, while spring MTTgeo varied from 0.5 to 1.9 years. The modelled variation in annual and seasonal MTTgeo and the fraction of young water (<3 months) was supported by extensive observations of both δ18O and base cation concentrations in the different streams. The travel time of water to streams was positively correlated with the area coverage of low-conductive silty sediments (r=0.90, P<0.0001). Catchments with mixed soil–landscape settings typically displayed larger variability in seasonal MTTgeo, as contrasting hydrological responses between different soil types (e.g. peat in mires, till and silty sediments) are integrated. The areal coverage of mires was especially important for the young water contribution in spring (r=0.96, P<0.0001). The main factor for this was attributed to extensive soil frost in mires, causing considerable overland flow during the snowmelt period. However, this lower groundwater recharge during snowmelt caused mire-dominated catchments to have longer stream runoff MTTgeo than comparable forest catchments in winter. Boreal landscapes are sensitive to climate change, and our results suggest that changes in seasonality are likely to cause contrasting responses in different catchments depending on the dominating landscape type.

Soil and Stream Water Chemistry During Spring Snowmelt

1992 ◽  
Vol 23 (1) ◽  
pp. 13-26 ◽  
Author(s):  
W. H. Hendershot ◽  
L. Mendes ◽  
H. Lalande ◽  
F. Courchesne ◽  
S. Savoie
Keyword(s):  
Stream Water ◽  
Base Cations ◽  
Stream Chemistry ◽  
Stream Water Chemistry ◽  
The Matrix ◽  
Adsorption Desorption ◽  
The Relationship ◽  
Best Fit ◽  
Spring Snowmelt ◽  
Over Time

In order to determine how water flowpath controls stream chemistry, we studied both soil and stream water during spring snowmelt, 1985. Soil solution concentrations of base cations were relatively constant over time indicating that cation exchange was controlling cation concentrations. Similarly SO4 adsorption-desorption or precipitation-dissolution reactions with the matrix were controlling its concentrations. On the other hand, NO3 appeared to be controlled by uptake by plants or microorganisms or by denitrification since their concentrations in the soil fell abruptly as snowmelt proceeded. Dissolved Al and pH varied vertically in the soil profile and their pattern in the stream indicated clearly the importance of water flowpath on stream chemistry. Although Al increased as pH decreased, the relationship does not appear to be controlled by gibbsite. The best fit of calculated dissolved inorganic Al was obtained using AlOHSO4 with a solubility less than that of pure crystalline jurbanite.

scholarly journals Riparian zone control on base cation concentration in boreal streams

2013 ◽  
Vol 10 (6) ◽  
pp. 3849-3868 ◽  
Author(s):  
J. L. J. Ledesma ◽  
T. Grabs ◽  
M. N. Futter ◽  
K. H. Bishop ◽  
H. Laudon ◽  
...  
Keyword(s):  
Stream Water ◽  
Temporal Stability ◽  
Base Cations ◽  
Base Cation ◽  
Forest Harvesting ◽  
Negative Consequences ◽  
Integration Model ◽  
Groundwater Levels ◽  
Zone Control ◽  
Precipitation Regimes

Abstract. Riparian zones (RZ) are a major factor controlling water chemistry in forest streams. Base cations' (BC) concentrations, fluxes, and cycling in the RZ merit attention because a changing climate and increased forest harvesting could have negative consequences, including re-acidification, for boreal surface waters. We present a two-year study of BC and silica (Si) flow-weighted concentrations from 13 RZ and 14 streams in different landscape elements of a boreal catchment in northern Sweden. The spatial variation in BC and Si dynamics in both RZ and streams was explained by differences in landscape element type, with highest concentrations in silty sediments and lowest concentrations in peat-dominated wetland areas. Temporal stability in BC and Si concentrations in riparian soil water, remarkably stable Mg/Ca ratios, and homogeneous mineralogy suggest that patterns found in the RZ are a result of a distinct mineralogical upslope signal in groundwater. Stream water Mg/Ca ratios indicate that the signal is subsequently maintained in the streams. Flow-weighted concentrations of Ca, Mg, and Na in headwater streams were represented by the corresponding concentrations in the RZ, which were estimated using the Riparian Flow-Concentration Integration Model (RIM) approach. Stream and RZ flow-weighted concentrations differed for K and Si, suggesting a stronger biogeochemical influence on these elements, including K recirculation by vegetation and retention of Si within the RZ. Potential increases in groundwater levels linked to forest harvesting or changes in precipitation regimes would tend to reduce BC concentrations from RZ to streams, potentially leading to episodic acidification.

scholarly journals Trends and seasonality in stream water chemistry in two moorland catchments of the Upper River Wye, Plynlimon

1997 ◽  
Vol 1 (3) ◽  
pp. 571-581 ◽  
Author(s):  
B. Reynolds ◽  
M. Renshaw ◽  
T. H. Sparks ◽  
S. Crane ◽  
S. Hughes ◽  
...  
Keyword(s):  
Water Chemistry ◽  
Stream Water ◽  
Base Cation ◽  
Solute Concentration ◽  
Seasonal Effects ◽  
Quality Data ◽  
Water Quality Data ◽  
Agricultural Improvement ◽  
Stream Water Chemistry

Abstract. Stream water chemistry in the Cyff and Gwy subcatchments within the headwaters of the River Wye has been monitored regularly since 1980. In the Gwy, which is a predominantly semi-natural grassland catchment, land use has remained relatively static over the monitoring period, whilst the Cyff catchment is more buffered because of base cation inputs from agricultural improvement and ground water sources. Using a variety of statistical techniques, the long-term data are examined for evidence of trends after eliminating seasonal effects. The results highlight some of the difficulties associated with the analysis of longterm water quality data which show considerable variability over a variety of timescales. Some of this variability can be explained in terms of hydrochemical responses to climatic extremes and episodic events such as large atmospheric inputs of seasalts. The long-term fluctuations in solute concentration underline the continuing need for maintaining consistent long-term monitoring at sensitive upland sites if underlying trends related to gradual changes in pollutant deposition or climate are to be detected with any certainty.

Seasalt Effects on the Acid Neutralizing Capacity of Streamwaters in Southern Norway

1995 ◽  
Vol 26 (4-5) ◽  
pp. 369-388 ◽  
Author(s):  
Espen Lydersen ◽  
Arne Henriksen
Keyword(s):  
Stream Water ◽  
Base Cations ◽  
Acid Neutralizing Capacity ◽  
Neutral Salt ◽  
Exchange Reactions ◽  
Short Term ◽  
Sulphur Compounds ◽  
Neutralizing Capacity ◽  
Southern Norway

Input of neutral salt, primarily NaCl, from sea spray is an important factor for short-term acidification of surface water, primarily in already acidified areas, because Na may substitute for H+ and cationic aluminium by cation-exchange reactions in the soil. By evaluating the variation of non-marine sodium (Na*) separately it is possible to estimate the major effect of seasalt episodes on the neutralizing capacity (ANC) of stream water. At four long-term monitored Norwegian catchments, the Na* in stream water on average explained 28 ± 4% of the monthly variations of ANC in stream water at Birkenes, and 27 ± 3%, 20 ± 2% and 56 ± 5% of the correspondent variations at Storgama, Langtjern and Kaarvatn, during the respective monitoring periods. The remaining variations in acid neutralizing capacity are explained by the difference between non-marine base cations (ΣCa*,Mg*,K*) and non-marine sulphate (SO4*) and NO3. This paper also indicates that seasalt episodes are probably of greater importance for the periodic variations in ANC of stream water than commonly recognized. During the last years, extreme seasalt episodes have occurred in southern Norway, and more frequently at winter-time, which means that seasalt inputs have played a more important role for the short-term variations of ANC in stream water the last years. This tendency is also strengthened by the fact that there has been a significant decline in the input of acidic sulphur compounds and non-marine base cations in stream water during the last 10-15 years. Because the decline in soil-derived base cations in stream water is somewhat lower than the correspondent decline of sulphate, a slowly improving ANC of stream water should be expected on long-term basis. Seasalt episodes of the same magnitude as those present during the last years, will therefore most likely cause less extreme water-chemical conditions in the years to come. Because the seasalt effect seems to be a short-term effect, there is no reason to claim that these effects may cause long-term acidification, a conclusion earlier drawn from several correspondent studies.

Sensitivity of pH in a boreal stream network to a potential decrease in base cations caused by forest harvest

2010 ◽  
Vol 67 (7) ◽  
pp. 1116-1125 ◽  
Author(s):  
Anneli Ågren ◽  
Ishi Buffam ◽  
Kevin Bishop ◽  
Hjalmar Laudon
Keyword(s):  
Forest Cover ◽  
Stream Water ◽  
Base Cations ◽  
Forest Harvest ◽  
Stream Network ◽  
Stream Length ◽  
Forestry Practices ◽  
Long Term Effect ◽  
Spring Snowmelt

Increased forest harvest with more whole-tree utilization can decrease base cations (BC) in soils and stream runoff. This paper analyses how reducing stream BC changes the capacity of a boreal stream network to buffer pH changes. We estimated change in stream pH during spring snowmelt in 60 locations throughout a 68 km2 boreal catchment in northern Sweden with different scenarios of BC removal from stream water ranging from 10 to 50 µequiv.·L–1. The pH decreased in all scenarios, and if BC decreased by 50 µequiv.·L–1, stream length with pH above the acid threshold pH 5 during spring snowmelt decreased from 82% to 44% of the stream network, whereas the stream length with pH above 5.5 decreased from 60% to 10%. The pH sensitivity of different stream reaches to reductions in BC was positively related to the slope of the catchment, forest cover, and forested mires, whereas it was negatively related to the percentage of agricultural fields. Because the long-term effect of different forestry practices on stream BC is unclear, there is all the more reason to evaluate BC sensitivity before, rather than after, eventual problems arise.

scholarly journals Weathering rates in Swedish forest soils

2019 ◽  
Vol 16 (22) ◽  
pp. 4429-4450 ◽  
Author(s):  
Cecilia Akselsson ◽  
Salim Belyazid ◽  
Johan Stendahl ◽  
Roger Finlay ◽  
Bengt A. Olsson ◽  
...  
Keyword(s):  
Base Cations ◽  
Sustainable Forestry ◽  
Base Cation ◽  
Forest Growth ◽  
Forest Fuels ◽  
Weathering Rates ◽  
Whole Tree Harvesting ◽  
Whole Tree ◽  
Tree Harvesting

Abstract. Soil and water acidification was internationally recognised as a severe environmental problem in the late 1960s. The interest in establishing “critical loads” led to a peak in weathering research in the 1980s and 1990s, since base cation weathering is the long-term counterbalance to acidification pressure. Assessments of weathering rates and associated uncertainties have recently become an area of renewed research interest, this time due to demand for forest residues to provide renewable bioenergy. Increased demand for forest fuels increases the risk of depleting the soils of base cations produced in situ by weathering. This is the background to the research programme Quantifying Weathering Rates for Sustainable Forestry (QWARTS), which ran from 2012 to 2019. The programme involved research groups working at different scales, from laboratory experiments to modelling. The aims of this study were to (1) investigate the variation in published weathering rates of base cations from different approaches in Sweden, with consideration of the key uncertainties for each method; (2) assess the robustness of the results in relation to sustainable forestry; and (3) discuss the results in relation to new insights from the QWARTS programme and propose ways to further reduce uncertainties. In the study we found that the variation in estimated weathering rates at single-site level was large, but still most sites could be placed reliably in broader classes of weathering rates. At the regional level, the results from the different approaches were in general agreement. Comparisons with base cation losses after stem-only and whole-tree harvesting showed sites where whole-tree harvesting was clearly not sustainable and other sites where variation in weathering rates from different approaches obscured the overall balance. Clear imbalances appeared mainly after whole-tree harvesting in spruce forests in southern and central Sweden. Based on the research findings in the QWARTS programme, it was concluded that the PROFILE/ForSAFE family of models provides the most important fundamental understanding of the contribution of weathering to long-term availability of base cations to support forest growth. However, these approaches should be continually assessed against other approaches. Uncertainties in the model approaches can be further reduced, mainly by finding ways to reduce uncertainties in input data on soil texture and associated hydrological parameters but also by developing the models, e.g. to better represent biological feedbacks under the influence of climate change.

Long-term trends in catchment export and lake concentrations of base cations in the Dorset study area, central Ontario

2008 ◽  
Vol 65 (5) ◽  
pp. 809-820 ◽  
Author(s):  
L A Molot ◽  
Peter J Dillon
Keyword(s):  
Surface Waters ◽  
Base Cations ◽  
Base Cation ◽  
Monovalent Cation ◽  
Eastern North America ◽  
Dry Period ◽  
Forested Catchments ◽  
Long Term Trends ◽  
High Runoff

Decreases in exchangeable base cation reservoirs, base cation export, and lake concentrations have been reported for acid-sensitive regions in Europe and eastern North America. These decreases have produced smaller than anticipated increases in alkalinity in surface waters in response to reductions in sulphate emissions and may have ecological consequences. This study presents annual export rates of Ca, Mg, K, and Na from 20 forested catchments between 1978 and 1998 and concentrations in seven downstream lakes between 1975 and 2005 in an acid-sensitive region of central Ontario, Canada. In contrast to monovalent cation export, decreases in divalent cation export continued after an extended dry period ended. Lake concentration trends showed three distinct periods. The first period (1975–1976 to 1982–1983) coincided with high runoff and was characterized by relatively high Ca, Mg, and K concentrations. This was followed by a 10-year period of fluctuations around the long-term mean. Concentrations then dropped below the long-term means and remained 5%–20% below the means until 2004–2005. The latter trend in lake concentrations suggests that export likely remained low but stable after May 1998 (the last month for which export data are available). Na increased between 250% and 350% in Dickie and Harp lakes as a result of road salt contamination.

scholarly journals Long-term trends of water chemistry in mountain streams in Sweden – slow recovery from acidification

2013 ◽  
Vol 10 (8) ◽  
pp. 12849-12885
Author(s):  
H. Borg ◽  
M. Sundbom
Keyword(s):  
Water Chemistry ◽  
Major Ions ◽  
Stream Water ◽  
Base Cations ◽  
High Flow ◽  
Base Flow ◽  
Precipitation Trend ◽  
Sulphur Deposition ◽  
Long Term Trends

Abstract. The water chemistry of streams and precipitation in the province of Jämtland, northern Sweden has been monitored since the 1980s to study long-term trends, occurrence of acid episodes, and effects of liming. The acidity and sulphur in precipitation increased in the 1970s, followed by a loss of ANC and low pH in the streams. Sulphur deposition begun to decrease in the 1980s, until approximately 2000, after which the decrease levelled out. The stream water sulphate followed the precipitation trend but decreased more slowly and since the late 1990s a subtle increase was observed. The sulphate concentrations in the snow have generally been higher than or equal to the stream sulphate levels. Since 2005, stream sulphate has sometimes exceeded snow sulphate, indicating desorption of stored soil sulphate, possibly because of climate related changes in run-off routes through the soil profiles, following shorter periods of frost. Up to 2000, TOC increased by approximately 0.1 mg L−1 yr−1. The mean trends in sulphate and TOC from approximately 1990 until today are generally opposite. Acidic episodes with pH 4.0 at flow peaks occurred frequently in the unlimed streams, despite relatively well buffered waters at base flow. To evaluate the main causes for the loss of ANC, the changes in major ions during high flow were calculated. The most important contribution resulted from dilution of base cations, with contribution from organic anions. Sulphate also had some influence, as it was somewhat enriched or only slightly diluted during high flow. Wetland liming started in 1985 after which the earlier observed extreme peak values of Fe, Mn and Al, did not return. The studied area is remote from emission sources in Europe, but the critical load of acidity is still exceeded. The long-term recovery observed in the unlimed streams is thus slow, and severe acidic episodes still occur.

scholarly journals Long-term trends of water chemistry in mountain streams in Sweden – slow recovery from acidification

2014 ◽  
Vol 11 (1) ◽  
pp. 173-184 ◽  
Author(s):  
H. Borg ◽  
M. Sundbom
Keyword(s):  
Water Chemistry ◽  
Stream Water ◽  
Base Cations ◽  
Acid Neutralizing Capacity ◽  
Precipitation Trend ◽  
Run Off ◽  
Neutralizing Capacity ◽  
Recovery From Acidification ◽  
Long Term Trends

Abstract. The water chemistry of streams and precipitation in the province of Jämtland, northern Sweden has been monitored since the 1980s to study long-term trends, occurrence of acid episodes, and effects of liming. The acidity in precipitation increased in the 1970s, followed by a loss of acid neutralizing capacity (ANC) and low pH in the streams. Sulfur deposition began to decrease in the 1980s, until approximately 2000, after which the decrease levelled out. Stream water sulfate concentration followed the precipitation trend but decreased more slowly and since the late 1990s a subtle increase was observed. Sulfate concentrations in the snow typically have been higher than or equal to the stream sulfate levels. However, during the period of rapid deposition decrease and also since 2005 stream sulfate has sometimes exceeded snow sulfate, indicating desorption of stored soil sulfate, possibly because of climate-related changes in run-off routes through the soil profiles, following shorter periods of frost. From 1982 to 2000, total organic carbon (TOC) increased by approximately 0.1 mg L−1 yr−1. The mean trends in sulfate and TOC from approximately 1990 until today were generally opposite. Acidic episodes with pH 4.0 at flow peaks occurred frequently in the unlimed streams, despite relatively well-buffered waters at baseflow. To evaluate the main causes for the loss of ANC during episodes, the changes in major ion concentrations during high flow episodes were evaluated. The most important factors contributing to ANC loss were dilution of base cations (Na+, K+, Ca2+, Mg2+), enrichment of organic anions and enrichment of sulfate. Wetland liming started in 1985 after which the earlier observed extreme peak values of iron, manganese and aluminium, did not reoccur. The studied area is remote from emission sources in Europe, but the critical load of acidity is still exceeded. The long-term recovery observed in the unlimed streams is thus slow, and severe acidic episodes still occur.

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