Impacts of Climate on the Flux of Dissolved Organic Carbon from Catchments

Jennings, Eleanor; Järvinen, Marko; Allott, Norman; Арвола, Лаури; Moore, Karen; Naden, Pamela S.; Aonghusa, Caitríona Nic; Nõges, Tiina; Weyhenmeyer, Gesa A.

doi:10.1007/978-90-481-2945-4_12

Cited by 31 publications

(33 citation statements)

References 76 publications

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“…lakes and streams in the UK as well as lakes in the US and Scandinavia (Erlandsson et al, 2008;Evans et al, 2005Evans et al, , 2006Monteith et al, 2007;Winterdahl et al, 2011). In those studies, it was concluded that in addition to climate-related effects (Freeman, 2004;Weyhenmeyer and Karlsson, 2009;Jennings et al, 2010), there was a connection between the decreased acid deposition and the increased run-off of organic carbon to streams and lakes in regions previously affected by higher load of acidifying substances. The observed trend in organic carbon in our streams may thus be a result of changed acid deposition and also of a changing climate.…”

Section: Water Chemistry: Long-term Trendsmentioning

confidence: 99%

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

Borg

Sundbom

2014

Biogeosciences

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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.

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Section: Water Chemistry: Long-term Trendsmentioning

confidence: 99%

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

Borg

Sundbom

2014

Biogeosciences

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“…Anthropogenic acidification has been known to occur due to afforestation (Battarbee et al, 2010) and peat degradation and associated DOC leaching and increased pH (Monteith and Evans, 2005;Jennings et al, 2010). It is also possible that these assemblages represent naturally acidic conditions.…”

Section: Low Alkalinity Gradientmentioning

confidence: 99%

Diatom assemblages and their associated environmental factors in upland peat forest rivers

O’Driscoll

Eyto

Rodgers

et al. 2012

Ecological Indicators

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The acid-sensitive upland blanket peat catchments are important habitats for diatom assemblages.In this study, the distribution patterns of epilithic diatom assemblages in the streams of upland forested blanket peat in north-west of Ireland are presented and the associated environmental factors are discussed. A total of 43 sites in 16 rivers were sampled. Multivariate analysis highlighted alkalinity and conductivity as the main physicochemical drivers of riverine diatom assemblages. Contrary to expectations nutrients were not found to have a major influence on the diatoms. A major flood event had a significant impact on the diatom assemblage, and one year after the event, long stalked diatom taxa were still largely absent from the river, indicating that floods could be one of the important factors affecting diatom assemblages. However, the ecological status of the affected sites, as determined by the EQR, did not alter from before to after the flood. The results of this study could be applied to similar acid-sensitive upland peat forest catchments and used as the benchmark to assess the impact of forest operations and peat degradation on ecological status.

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“…Widespread increases in DOC have been attributed primarily to recovery from acidification (Monteith et al 2007). Increased precipitation may also increase terrestrial DOC loading to lakes, and anthropogenically induced changes in the volume, timing, and magnitude of extreme precipitation events may also drive regional changes in DOC (Jennings et al 2010).…”

mentioning

confidence: 99%

Physical responses of small temperate lakes to variation in dissolved organic carbon concentrations

Read

Rose

2013

Limnology & Oceanography

163

154

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We used a mechanistic physical model to examine the effect of variability in dissolved organic carbon (DOC) concentrations on the physical properties of small temperate lakes. The model was validated on eight small (6 3 10 24 to 3.8 3 10 22 km 2 ) lakes in Wisconsin and Michigan, with a standard error , 1uC for seven of eight lakes. Attenuation of photosynthetically active radiation (400-700 nm) in these lakes was regulated by DOC concentrations and was important in the vertical structuring of water temperatures. Heat exchange below the surface mixed layer was near the molecular rate, increasing the importance of water clarity as a control on the heat content of deeper waters. To understand the thermal effects of changing DOC concentrations, we applied scenarios of a 50% increase and 50% decrease in DOC concentrations for one lake (Trout Bog) and found water temperatures to vary in response, with the seasonally averaged temperatures in the increased DOC scenario being . 2uC colder than the reduced scenario. We found a nonlinear relationship between DOC and temperature, with clearer (lower DOC) simulations being more sensitive to climate variability, suggesting that DOC may act as a buffer against a warming climate. Our model showed that DOC also influenced epilimnetic depths, as nocturnal mixing (related to the vertical partitioning of heat) was more important than wind-driven mixing. Small lakes are globally important regulators of biogeochemical cycles and are structurally different from larger lakes. Important feedbacks to physical processes must be accounted for when understanding the effects of changing DOC and climate on small lakes.

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Impacts of Climate on the Flux of Dissolved Organic Carbon from Catchments

Cited by 31 publications

References 76 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

Diatom assemblages and their associated environmental factors in upland peat forest rivers

Physical responses of small temperate lakes to variation in dissolved organic carbon concentrations

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