Drivers and evolution of episodic acidification at the Bear Brook Watershed in Maine, USA

Laudon, Hjalmar; Norton, Stephen A.

doi:10.1007/s10661-010-1526-0

Cited by 16 publications

(11 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Wigington et al (1996) found that dilution of base cations provided the most important contributions to the ANC depressions during episodes in streams in the northeastern USA, with some contributions from organic anions and sulfate. In an experimental study where ammonium sulfate repeatedly was added to the Bear Brook Watershed in north-eastern USA, sulfate was the most important driver of the loss of ANC, and the acid episodes were mostly associated with snow melt events and showed a steady increase following the start of the treatment (Laudon and Norton, 2010).…”

Section: Water Chemistry: Seasonal Variationsmentioning

confidence: 99%

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

Borg

Sundbom

2014

Biogeosciences

View full text Add to dashboard Cite

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 runoff 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 wellbuffered 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 + , Ca 2+ , Mg 2+ ), 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.

show abstract

Section: Water Chemistry: Seasonal Variationsmentioning

confidence: 99%

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

Borg

Sundbom

2014

Biogeosciences

View full text Add to dashboard Cite

show abstract

“…DOC concentration is typically slightly higher in the reference stream than in the treatment stream (mean concentration of 1.9 and 1.5 mg L )1 , respectively), and there are no long-term trends in either stream . Since initiation of the treatment, mean annual pH has been 5.48 in the REF stream and 5.25 in the TRT stream (Laudon & Norton, 2010). The N enrichment and acidification in the TRT catchment have resulted in elevated N and P foliar concentrations compared to REF foliage (Elvir et al, 2005).…”

Section: Study Site Descriptionmentioning

confidence: 99%

Chronic catchment nitrogen enrichment and stoichiometric constraints on the bioavailability of dissolved organic matter from leaf leachate

et al. 2012

Self Cite

View full text Add to dashboard Cite

Summary 1. Chronic nitrogen (N) deposition may alter the bioavailability of dissolved organic matter (DOM) in streams by multiple pathways. Elevated N deposition may alter the nutrient stoichiometry of DOM as well as nutrient availability in stream water. 2. We evaluated the influence of a decadal‐scale experimental N enrichment on the relative importance of DOM nutrient content and inorganic nutrient availability on the bioavailability of DOM. We measured the consumption of dissolved organic carbon (DOC) and changes in nutrient concentration, DOM components and enzyme activity in a bottle incubation assay with different DOM and nutrient treatments. To evaluate the effect of DOM stoichiometry, we used leaf leachates of different carbon/N/phosphorus (C : N :P) ratio, made from leaf litter sourced in the reference and N‐enriched catchments at the Bear Brook Watershed in Maine (BBWM). We also manipulated the concentration of inorganic N and P to compare the effect of nutrient enrichment with DOM stoichiometry. 3. DOC from the N‐enriched catchment was consumed 14% faster than that from the reference catchment. However, mean DOC consumption for both leachates was more than doubled by the simultaneous addition of N and P, compared to controls, while the addition of N or P alone increased consumption by 42 and 23%, respectively. The effect of N and/or P enrichment consistently had a greater effect than DOM source for all response variables considered. 4. We subsequently conducted DOC uptake measurements using leaf leachate addition under ambient and elevated N and P in the streams draining the reference and N‐enriched catchments at BBWM. In both streams, DOC uptake lengths were shorter when N and P were elevated. 5. Although both DOM stoichiometry and inorganic nutrient availability affect DOM bioavailability, N and P co‐limitation appears to be the dominant driver of reach‐scale processing of DOM.

show abstract

“…4, 7, and 8 decline even during low flow (base flow) months. Laudon and Norton (2010) describe mechanisms of acidification during episodic hydrologic events.…”

Section: Ph (−Log [H + ])mentioning

confidence: 99%

Twenty-year inter-annual trends and seasonal variations in precipitation and stream water chemistry at the Bear Brook Watershed in Maine, USA

Navrátil

Norton

Fernandez

et al. 2010

Environ Monit Assess

Self Cite

View full text Add to dashboard Cite

Mean annual concentration of SO4(-2) in wet-only deposition has decreased between 1988 and 2006 at the paired watershed study at Bear Brook Watershed in Maine, USA (BBWM) due to substantially decreased emissions of SO(2). Emissions of NO(x) have not changed substantially, but deposition has declined slightly at BBWM. Base cations, NH4+, and Cl(-) concentrations were largely unchanged, with small irregular changes of <1 μeq L(-1) per year from 1988 to 2006. Precipitation chemistry, hydrology, vegetation, and temperature drive seasonal stream chemistry. Low flow periods were typical in June-October, with relatively greater contributions of deeper flow solutions with higher pH; higher concentrations of acid-neutralizing capacity, Si, and non-marine Na; and low concentrations of inorganic Al. High flow periods during November-May were typically dominated by solutions following shallow flow paths, which were characterized by lower pH and higher Al and DOC concentrations. Biological activity strongly controlled NO3- and K(+). They were depressed during the growing season and elevated in the fall. Since 1987, East Bear Brook (EB), the reference stream, has been slowly responding to reduced but still elevated acid deposition. Calcium and Mg have declined fairly steadily and faster than SO4(-2), with consequent acidification (lower pH and higher inorganic Al). Eighteen years of experimental treatment with (NH(4))(2)SO(4) enhanced acidification of West Bear Brook's (WB) watershed. Despite the manipulation, NH4+ concentration remained below detection limits at WB, while leaching of NO3- increased. The seasonal pattern for NO3- concentrations in WB, however, remained similar to EB. Mean monthly concentrations of SO4(-2) have increased in WB since 1989, initially only during periods of high flow, but gradually also during base flow. Increases in mean monthly concentrations of Ca(2+), Mg(2+), and K(+) due to the manipulation occurred from 1989 until about 1995, during the depletion of base cations in shallow flow paths in WB. Progressive depletion of Ca and Mg at greater soil depth occurred, causing stream concentrations to decline to pre-manipulation values. Mean monthly Si concentrations did not change in EB or WB, suggesting that the manipulation had no effect on mineral weathering rates. DOC concentrations in both streams did not exhibit inter- or intra-annual trends.

show abstract

Drivers and evolution of episodic acidification at the Bear Brook Watershed in Maine, USA

Cited by 16 publications

References 53 publications

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

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

Chronic catchment nitrogen enrichment and stoichiometric constraints on the bioavailability of dissolved organic matter from leaf leachate

Twenty-year inter-annual trends and seasonal variations in precipitation and stream water chemistry at the Bear Brook Watershed in Maine, USA

Contact Info

Product

Resources

About