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 Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

2001 ◽  
Vol 5 (3) ◽  
pp. 451-458 ◽  
Author(s):  
R. C. Helliwell ◽  
R. C. Ferrier ◽  
L. Johnston ◽  
J. Goodwin ◽  
R. Doughty
Keyword(s):  
Surface Waters ◽  
Chemical Recovery ◽  
Dry Period ◽  
Sulphur Deposition ◽  
South West ◽  
Recovery From Acidification ◽  
Long Term Trends ◽  
Acid Status ◽  
Annual Discharge

Abstract. The long term response of surface waters to changes in sulphur deposition and afforestation is investigated for three upland river systems in the Galloway region of south-west Scotland. From 1984-1999, these rivers exhibited a statistically significant decline in non-marine sulphate concentrations in response to reduced acid deposition. This reduction in non-marine sulphate was, however, insufficient to induce a pH recovery over the period. A statistically significant increase in river pH was observed between 1956-1970 (0.05 yr-1) when subsidised agricultural lime payments were at a maximum. In 1976, this subsidy ceased and surface waters have progressively acidified. In addition, climatic change is found to influence long-term trends in pH. Mean annual pH was greatest during a dry period between 1969-1973 when total annual discharge was low. Thereafter, pH declined gradually in response to higher rainfall and increased total annual discharge. Overall, surface waters draining the afforested catchments of the Rivers Cree and Bladnoch are more acid than those draining the moorland catchment of the Luce. These results indicate that in afforested catchments, current reductions in sulphur emissions have not led to an observed improvement in the acid status of surface waters. Forestry, therefore, represents a confounding factor with regard to chemical recovery from acidification in this region. Keywords: acidification, afforestation, deposition, rivers, lochs, non-marine sulphate, pH

Base cation reservoirs in soil control the buffering capacity of lakes in forested catchments

2006 ◽  
Vol 63 (3) ◽  
pp. 471-474 ◽  
Author(s):  
Daniel Houle ◽  
Rock Ouimet ◽  
Suzanne Couture ◽  
Christian Gagnon
Keyword(s):  
Surface Water ◽  
North America ◽  
Surface Waters ◽  
Base Cations ◽  
Base Cation ◽  
Acid Neutralizing Capacity ◽  
Forested Catchments ◽  
Northeastern North America ◽  
Poor Recovery ◽  
Neutralizing Capacity

The acidification of forest soils and surface waters and their relatively poor recovery record following reductions in atmospheric sulphur emissions is a major ongoing environmental problem, particularly in northeastern North America. The slow recovery of surface water is widely hypothesized to result from depletion of reservoirs of base cations in soil. This is concordant with the theory that the acid-neutralizing capacity (ANC) of lakes is likely proportional to the size of the exchangeable base cation reservoirs present in surrounding watershed soils. However, data describing these linkages are still nonexistent in the literature. Here we show that lake ANC is highly predictable (r2 = 0.75) based on the size of the exchangeable Ca2+ reservoir in soil in 21 catchments representative of soil and lake conditions encountered in northeastern North America. This finding indirectly supports the hypothesis that the poor recovery of surface water from acidification is governed by the size of base cation reservoirs present in catchment soils. The size of the base cation reservoir in soil is thus a strong indicator of the acid–base status of both soils and surface waters.

Modelling the Effects of Acid Deposition: Estimation of Long-Term Water Quality Responses in Forested Catchments in Finland

1988 ◽  
Vol 19 (2) ◽  
pp. 99-120 ◽  
Author(s):  
A. Lepistö ◽  
P. G. Whitehead ◽  
C. Neal ◽  
B. J. Cosby
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
Base Cations ◽  
Surface Water Quality ◽  
Mineral Weathering ◽  
Co2 Solubility ◽  
Forested Catchments ◽  
Deposition Rates ◽  
Magic Model

A modelling study has been undertaken to investigate long-term changes in surface water quality in two contrasting forested catchments; Yli-Knuutila, with high concentrations of base cations and sulphate, in southern Finland; and organically rich, acid Liuhapuro in eastern Finland. The MAGIC model is based on the assumption that certain chemical processes (anion retention, cation exchange, primary mineral weathering, aluminium dissolution and CO2 solubility) in catchment soils are likely keys to the responses of surface water quality to acidic deposition. The model was applied for the first time to an organically rich catchment with high quantities of humic substances. The historical reconstruction of water quality at Yli-Knuutila indicates that the catchment surface waters have lost about 90 μeq l−1 of alkalinity in 140 years, which is about 60% of their preacidification alkalinity. The model reproduces the declining pH levels of recent decades as indicated by paleoecological analysis. Stream acidity trends are investigated assuming two scenarios for future deposition. Assuming deposition rates are maintained in the future at 1984 levels, the model indicates that stream pH is likely to continue to decline below presently measured levels. A 50% reduction in deposition rates would likely result in an increase in pH and alkalinity of the stream, although not to estimated preacidification levels. Because of the high load of organic acids to the Liuhapuro stream it has been acid before atmospheric pollution; a decline of 0.2 pH-units was estimated with increasing leaching of base cations from the soil despite the partial pH buffering of the system by organic compounds.

Hypolimnion Injection of Nutrient Effluents as a Method for Reducing Eutrophication

1980 ◽  
Vol 37 (3) ◽  
pp. 320-327 ◽  
Author(s):  
D. W. Schindler ◽  
T. Ruszczynski ◽  
E. J. Fee
Keyword(s):  
Surface Waters ◽  
Standing Crop ◽  
Nutrient Concentrations ◽  
Precambrian Shield ◽  
Water Interaction ◽  
Anoxic Hypolimnion ◽  
Long Term Trends

Injection of nutrients into the anoxic hypolimnion of a small Precambrian Shield lake for 5 yr caused less of a eutrophication problem than discharging nutrients into surface waters. Phytoplankton standing crop and production in the whole lake averaged only 10–21% of values in a nearby lake fertilized at the surface. Five-year averages for the epilimnion only were still lower: 5–8% of those in the surface-fertilized lake. Analysis of long-term trends in chlorophyll and nutrient concentrations revealed much slower rates of increase than in surface-fertilized lakes.Key words: eutrophication, hypolimnion injection, sediment–water interaction, nutrients, experimental lakes

scholarly journals Winter climate affects long-term trends in stream water nitrate in acid-sensitive catchments in southern Norway

2007 ◽  
Vol 4 (5) ◽  
pp. 3055-3085 ◽  
Author(s):  
H. A. de Wit ◽  
A. Hindar ◽  
L. Hole
Keyword(s):  
Snow Depth ◽  
Stream Water ◽  
N Deposition ◽  
Climatic Changes ◽  
N Leaching ◽  
Forested Catchments ◽  
Discharge Temperature ◽  
Long Term Trends ◽  
Southern Norway

Abstract. Controls of stream water NO3 in mountainous and forested catchments are not thoroughly understood. Long-term trends in stream water NO3 are positive, neutral and negative, often apparently independent of trends in N deposition. Here, time series of NO3 in four small acid-sensitive catchments in southern Norway were analysed in order to identify likely drivers of long-term changes in NO3. In two sites, stream water NO3 export declined ca 50% over a period of 25 years while in the other sites NO3 export increased with roughly 20%. Discharge and N deposition alone were poor predictors of these trends. The most distinct trends in NO3 were found in winter and spring. Empirical models explained between 45% and 61% of the variation in weekly concentrations of NO3, and described both upward and downward seasonal trends tolerably well. Key explaining variables were snow depth, discharge, temperature and N deposition. All catchments showed reductions in snow depth and increases in winter discharge. In two inland catchments, located in moderate N deposition areas, these climatic changes appeared to drive the distinct decreases in winter and spring concentrations and fluxes of NO3. In a coast-near mountainous catchment in a low N deposition area, these climatic changes appeared to have the opposite effect, i.e. lead to increases in especially winter NO3. This suggests that the effect of a reduced snow pack may result in both decreased and increased catchment N leaching depending on interactions with N deposition, soil temperature regime and winter discharge.

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 Ambiguities in the classification of Cochin Estuary, West Coast of India

2013 ◽  
Vol 10 (3) ◽  
pp. 3595-3628 ◽  
Author(s):  
A. Shivaprasad ◽  
J. Vinita ◽  
C. Revichandran ◽  
N. T. Manoj ◽  
K. V. Jayalakshmy ◽  
...  
Keyword(s):  
Data Sets ◽  
Dry Period ◽  
Cochin Estuary ◽  
Short Term ◽  
Classification Schemes ◽  
Biological Features ◽  
High Runoff ◽  
Long Term Variations

Abstract. Cochin Estuary is a unique complex system along Indian coastline with a widespread area at the upstream. The fluctuations in salinity are of extreme kind ranging from entirely riverine to entirely saline. The high runoff months are characterized by monsoonal spells causing intense flushing. During the peak dry period, the runoff is less but steady providing a stable environment. River runoff is controlled by short term variations rather than long term variations. Using large comprehensive data sets, an attempt is made to evaluate several classification schemes for the estuary. The existing methods proved to be insufficient to represent the real salient features of this typical estuary. Arguments are also presented to illustrate the confusion in the names by which the estuary is commonly known. Therefore, a new nomenclature is proposed as "Cochin Monsoonal Estuarine Bay" embodying the physiographic, hydrographic and biological features of the estuary.

scholarly journals Winter climate affects long-term trends in stream water nitrate in acid-sensitive catchments in southern Norway

2008 ◽  
Vol 12 (2) ◽  
pp. 393-403 ◽  
Author(s):  
H. A. de Wit ◽  
A. Hindar ◽  
L. Hole
Keyword(s):  
Snow Depth ◽  
Stream Water ◽  
N Deposition ◽  
Climatic Changes ◽  
N Leaching ◽  
Forested Catchments ◽  
Discharge Temperature ◽  
Long Term Trends ◽  
Southern Norway

Abstract. Controls of stream water NO3 in mountainous and forested catchments are not thoroughly understood. Long-term trends in stream water NO3 are positive, neutral and negative, often apparently independent of trends in N deposition. Here, time series of NO3 in four small acid-sensitive catchments in southern Norway were analysed in order to identify likely drivers of long-term changes in NO3. In two sites, stream water NO3 export declined ca 50% over a period of 25 years while in the other sites NO3 export increased with roughly 20%. Discharge and N deposition alone were poor predictors of these trends. The most distinct trends in NO3 were found in winter and spring. Empirical models explained between 45% and 61% of the variation in weekly concentrations of NO3, and described both upward and downward seasonal trends tolerably well. Key explaining variables were snow depth, discharge, temperature and N deposition. All catchments showed reductions in snow depth and increases in winter discharge. In two inland catchments, located in moderate N deposition areas, these climatic changes appeared to drive the distinct decreases in winter and spring concentrations and fluxes of NO3. In a coast-near mountainous catchment in a low N deposition area, these climatic changes appeared to have the opposite effect, i.e. lead to increases in especially winter NO3. This suggests that the effect of a reduced snow pack may result in both decreased and increased catchment N leaching depending on interactions with N deposition, soil temperature regime and winter discharge.

Long-term base cation weathering rates in forested catchments of the Canadian Shield

Geoderma ◽  
2015 ◽  
Vol 247-248 ◽  
pp. 12-23 ◽  
Author(s):  
Fougère Augustin ◽  
Daniel Houle ◽  
Christian Gagnon ◽  
François Courchesne
Keyword(s):  
Base Cation ◽  
Canadian Shield ◽  
Forested Catchments ◽  
Weathering Rates

scholarly journals Seasonal variation in aragonite saturation in surface waters of Puget Sound – a pilot study

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Gregory Pelletier ◽  
Mindy Roberts ◽  
Mya Keyzers ◽  
Simone R. Alin
Keyword(s):  
Pilot Study ◽  
Surface Waters ◽  
Puget Sound ◽  
Phytoplankton Production ◽  
Carbonate System ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Spatially Distributed ◽  
Long Term Trends

A pilot study of sampling, using monthly marine flights over spatially distributed stations, was conducted with the aim to characterize the carbonate system in Puget Sound over a full year-long period. Surface waters of Puget Sound were found to be under-saturated with respect to aragonite during October–March, and super-saturated during April–September. Highest pCO2 and lowest pH occurred during the corrosive October–March period. Lowest pCO2 and highest pH occurred during the super-saturated April–September period. The monthly variations in pCO2, pH, and aragonite saturation state closely followed the variations in monthly average chlorophyll a. Super-saturated conditions during April–September are likely strongly influenced by photosynthetic uptake of CO2 during the phytoplankton growing season. The relationship between phytoplankton production, the carbonate system, and aragonite saturation state suggests that long-term trends in eutrophication processes may contribute to trends in ocean acidification in Puget Sound.

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