Nitrogen and phosphorus concentrations in discharge from drained peatland forests are increasing

Nieminen, Mika; Sallantaus, Tapani; Ukonmaanaho, Liisa; Nieminen, Tiina M.; Sarkkola, Sakari

doi:10.1016/j.scitotenv.2017.07.210

Cited by 89 publications

(67 citation statements)

References 25 publications

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“…This suggests that land use does not directly intensify or lessen trends in TOC, with the notable exception of ditching: the higher the proportion of ditched area in the catchment, the steeper the increase in TOC concentrations over the 25 year study period. Previously, ditching has been shown to substantially affect stream water nutrient concentrations (Nieminen et al 2017). In this study, we could link, for the first time, ditching to upward trends of TOC concentrations at the downstream stations of larger rivers.…”

Section: Discussionmentioning

confidence: 85%

Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers

Asmala

Carstensen

Räike

2019

Environ. Res. Lett.

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Increases of riverine organic carbon concentrations have been observed across the northern hemisphere over the past few decades. These increases are the result of multiple environmental drivers, but the relative importance of the drivers is still unclear. We analyzed a dataset of >10 000 observations of riverine total organic carbon (TOC) concentrations and associated water chemistry and hydrological observations from 1993 to 2017. The observations span a ∼600 km north-south gradient from 30 individual river systems in Finland. Our data show significantly increasing TOC concentrations in 25 out of 30 systems, with an average increase from 12.0 to 15.1 mg l −1 . The observed increase in riverine TOC concentrations led to an increase of 0.28 Mt in annual TOC load to the Baltic Sea from 1993 level to 2017 level. We analyzed the role of three putative environmental drivers of the observed TOC trends. Multiple regression analysis revealed that the most common driver was discharge, which alone explained TOC increases in 13 rivers, whereas pH and temperature were less important drivers (sole predictor in one and zero rivers, respectively). Different permutations of these three drivers were also found to be significant; the combination of discharge and pH being the most common (4 rivers). Land use was not in general linked with trends in TOC, except for the proportion of ditched land in the catchment, which was significantly correlated with increases in TOC concentration. Land use showed significant relationships with trends in discharge and pH. We also found that catchment characteristics are regulating the extent of these regional or global environmental changes causing the upward trends of riverine organic carbon.

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Section: Discussionmentioning

confidence: 85%

Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers

Asmala

Carstensen

Räike

2019

Environ. Res. Lett.

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“…clear-cutting of forests, which seem to impact more on DOC and N export from soils (Nieminen 2004, Nieminen et al 2015. However, a recent study of drained boreal peatlands by Nieminen et al (2017) showed that N and P export declined after drainage at the level typical of natural mires within the first 20-30 years, but later in long-term increased again presumably due to erosion of highly degraded peat soil.…”

Section: Discussionmentioning

confidence: 99%

Changes in dissolved organic matter and microbial activity in runoff waters of boreal mires after restoration

et al. 2018

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A considerable proportion of boreal mires have been drained for soil amelioration purposes. In response to drainageinduced degradation, restoration practices have been implemented in recent decades. Restoration by raising the water level is often followed by changes in the quality of runoff waters, especially in concentrations of dissolved organic carbon (DOC), nitrogen (N) and phosphorus (total P, PO4-P). We studied how mire restoration affected bacterial production (BP), bacterial growth efficiency (BGE%) and respiration (R) in mire runoff waters from spruce swamps and Sphagnum pine bogs in south-central Finland. The quality of runoff water was monitored for eight years (2008-2015) and bacterial activity was measured during three years (2010-2012) at runoff weir sites, including two pristine controls, one drained control and four treatment sites. The concentrations of DOC, N and P increased for 3-5 years after restoration. The increased availability of nutrients was followed by doubled BP (from ca. 0.34 to 0.88 µmol C L-1 d-1 , averages of restored sites) and BGE% (from ca. 2.7% to 9.2%), whereas microbial respiration was only slightly increased. However, bacterial activity in mire waters was low compared with those generally measured in river and lake waters. This was presumably related to the recalcitrant quality of the mire-originated DOC, which was not clearly influenced by restoration. Dissolved organic matter (DOM) of low bioavailability contributes to browning of headwaters. As our study was focused only on short-term (1-5 years) effects, more research is needed for evaluating long-term impacts of peatland origin DOM on carbon fluxes, microbial activity and food webs of recipient aquatic ecosystems.

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“…Recent studies indicate considerably longer-term leaching impact from peatland-based forestry to water courses (Nieminen et al 2017(Nieminen et al , 2018a. The effects of forest-based bioeconomy management strategies to increase biomass production and its effect on water quality at landscape scale are inadequately understood (Laudon et al 2011).…”

Section: The Forestry Sector In the Nordic Countries And Its Impacts mentioning

confidence: 99%

Potential impacts of a future Nordic bioeconomy on surface water quality

Marttila

Lepistö

Tolvanen

et al. 2020

Ambio

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Nordic water bodies face multiple stressors due to human activities, generating diffuse loading and climate change. The ‘green shift’ towards a bio-based economy poses new demands and increased pressure on the environment. Bioeconomy-related pressures consist primarily of more intensive land management to maximise production of biomass. These activities can add considerable nutrient and sediment loads to receiving waters, posing a threat to ecosystem services and good ecological status of surface waters. The potential threats of climate change and the ‘green shift’ highlight the need for improved understanding of catchment-scale water and element fluxes. Here, we assess possible bioeconomy-induced pressures on Nordic catchments and associated impacts on water quality. We suggest measures to protect water quality under the ‘green shift’ and propose ‘road maps’ towards sustainable catchment management. We also identify knowledge gaps and highlight the importance of long-term monitoring data and good models to evaluate changes in water quality, improve understanding of bioeconomy-related impacts, support mitigation measures and maintain ecosystem services.

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Nitrogen and phosphorus concentrations in discharge from drained peatland forests are increasing

Cited by 89 publications

References 25 publications

Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers

Multiple anthropogenic drivers behind upward trends in organic carbon concentrations in boreal rivers

Changes in dissolved organic matter and microbial activity in runoff waters of boreal mires after restoration

Potential impacts of a future Nordic bioeconomy on surface water quality

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