scholarly journals Nitrogen and dissolved organic carbon (DOC) losses from an artificially drained grassland on organic soils

2014 ◽  
Vol 11 (15) ◽  
pp. 4123-4137 ◽  
Author(s):  
B. Tiemeyer ◽  
P. Kahle
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Arable Land ◽  
Organic Soils ◽  
N Losses ◽  
Total N ◽  
Dynamic Component ◽  
Small Catchment ◽  
Doc Concentration

Abstract. Nitrate–nitrogen (NO3–N) as well as dissolved organic carbon (DOC) and nitrogen (DON) concentrations and losses were studied for three and two years, respectively, in a small catchment dominated by a degraded peatland used as intensive grassland. Concentrations in the shallow groundwater were spatially and temporally very variable, with NO3–N being the most dynamic component (7.3 ± 12.5 mg L−1) and ranging from 0 to 79.4 mg L−1. Average NO3–N concentrations of 10.3 ± 5.4 mg L−1 (0 to 25.5 mg L−1) in the ditch draining the catchment and annual NO3–N losses of 19, 35 and 26 kg ha−1 confirmed drained peatlands as an important source of diffuse N pollution. The highest NO3–N losses occurred during the wettest year. Resulting from concentration of 2.4 ± 0.8 mg L−1 (0.7 to 6.2 mg L−1), DON added a further 4.5 to 6.4 kg ha−1 to the N losses and thus formed a relevant (15%) component of the total N losses. Ditch DOC concentrations of 24.9 ± 5.9 mg L−1 (13.1 to 47.7 mg L−1) resulted in DOC losses of 66 kg ha−1 in the wet year of 2006/2007 and 39 kg ha−1 in the dry year of 2007/2008. Ditch DOC concentration were lower than the groundwater DOC concentration of 50.6 ± 15.2 mg L−1 (14.9 to 88.5 mg L−1). Both DOC and N concentrations were governed by hydrological conditions, but NO3–N reacted much faster and clearer on rising discharge rates than DOC, which tended to be higher under drier conditions. In the third year of the study, the superposition of a very wet summer and land use changes from grassland to arable land in a part of the catchment suggests that, under re-wetting conditions with a high groundwater table in summer, NO3–N would diminish quickly, while DOC would remain on a similar level. Further intensification of the land use, on the other hand, would increase N losses to receiving water bodies.

scholarly journals Nitrogen and dissolved organic carbon (DOC) losses from an artificially drained grassland on organic soils

2014 ◽  
Vol 11 (2) ◽  
pp. 3023-3064 ◽  
Author(s):  
B. Tiemeyer ◽  
P. Kahle
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Arable Land ◽  
Shallow Groundwater ◽  
Organic Soils ◽  
N Losses ◽  
Total N ◽  
Dynamic Component ◽  
Small Catchment

Abstract. Nitrate-nitrogen (NO3-N) as well as dissolved organic carbon (DOC) and nitrogen (DON) concentrations and losses were studied for three respectively two years in a small catchment dominated by a degraded peatland used as intensive grassland. Concentrations in the shallow groundwater were spatially and temporally very variable with NO3-N being the most dynamic component (7.3 ± 12.5 mg L–1). Average NO3-N concentrations of 10.3 ± 5.4 mg L–1 in the ditch draining the catchment and annual NO3-N losses of 19, 35 and 26 kg ha–1 confirmed drained peatlands as an important source of diffuse N pollution. The highest NO3-N losses occurred during the wettest year. Resulting from concentrations of 2.4 ± 0.8 mg L–1, DON added further 4.5 to 6.4 kg ha–1 to the N losses and thus formed a relevant component of the total N losses. Ditch DOC concentrations of 24.9 ± 5.9 mg L–1 resulted in DOC losses of 66 kg ha–1 in the wet year 2006/07 and 39 kg ha–1 in the dry year 2007/08. Both DOC and N concentrations were governed by hydrological conditions, but NO3-N reacted much faster and clearer on rising discharge rates than DOC which tended to be higher under dryer conditions. In the third year of the study, the superposition of a very wet summer and land use changes from grassland to arable land in a part of the catchment suggests that under re-wetting conditions with a high groundwater table in summer, NO3-N would diminish quickly, while DOC would remain on a similar level. Further intensification of the land use, on the other hand, would increase N losses to receiving water bodies.

scholarly journals Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape

2012 ◽  
Vol 9 (11) ◽  
pp. 4513-4525 ◽  
Author(s):  
T. Wohlfart ◽  
J.-F. Exbrayat ◽  
K. Schelde ◽  
B. Christen ◽  
T. Dalgaard ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Agricultural Landscape ◽  
Agricultural Land ◽  
Stream Water ◽  
Organic Soils ◽  
Total N ◽  
Small Catchment ◽  
Landscape Characteristics ◽  
Intensively Managed

Abstract. The surrounding landscape of a stream has crucial impacts on the aquatic environment. This study pictures the hydro-biogeochemical situation of the Tyrebækken creek catchment in central Jutland, Denmark. The intensively managed agricultural landscape is dominated by rotational croplands. The small catchment mainly consist of sandy soil types besides organic soils along the streams. The aim of the study was to characterise the relative influence of soil type and land use on stream water quality. Nine snapshot sampling campaigns were undertaken during the growing season of 2009. Total dissolved nitrogen (TDN), nitrate (NO3−), ammonium nitrogen and dissolved organic carbon (DOC) concentrations were measured, and dissolved organic nitrogen (DON) was calculated for each grabbed sample. Electrical conductivity, pH and flow velocity were measured during sampling. Statistical analyses showed significant differences between the northern, southern and converged stream parts, especially for NO3− concentrations with average values between 1.4 mg N l−1 and 9.6 mg N l−1. Furthermore, throughout the sampling period DON concentrations increased to 2.8 mg N l−1 in the northern stream contributing up to 81% to TDN. Multiple-linear regression analyses performed between chemical data and landscape characteristics showed a significant negative influence of organic soils on instream N concentrations and corresponding losses in spite of their overall minor share of the agricultural land (12.9%). On the other hand, organic soil frequency was positively correlated to the corresponding DOC concentrations. Croplands also had a significant influence but with weaker correlations. For our case study we conclude that the fractions of coarse textured and organic soils have a major influence on N and DOC export in this intensively used landscape. Meanwhile, the contribution of DON to the total N losses was substantial.

Pulsed terrestrial organic carbon persists in an estuarine environment after major storm events

2020 ◽  
Author(s):  
Eero Asmala ◽  
Christopher Osburn ◽  
Ryan Paerl ◽  
Hans Paerl
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
River Estuary ◽  
River Mouth ◽  
Neuse River Estuary ◽  
Storm Events ◽  
Dynamic Component ◽  
Neuse River ◽  
Doc Concentration ◽  
A Minor

<p>The transport of dissolved organic carbon from land to ocean is a large and dynamic component of the global carbon cycle. Export of dissolved organic carbon from watersheds is largely controlled by hydrology, and is exacerbated by increasing major rainfall and storm events, causing pulses of terrestrial dissolved organic carbon (DOC) to be shunted through rivers downstream to estuaries. Despite this increasing trend, the fate of the pulsed terrestrial DOC in estuaries remains uncertain. Here we present DOC data from 1999 to 2017 in Neuse River Estuary (NC, USA) and analyze the effect of six tropical cyclones (TC) during that period on the quantity and fate of DOC in the estuary. We find that that TCs promote a considerable increase in DOC concentration near the river mouth at the entrance to the estuary, on average an increase of 200 µmol l<sup>-1</sup> due to storms was observed. TC-induced increases in DOC are apparent throughout the estuary, and the duration of these elevated DOC concentrations ranges from one month at the river mouth to over six months in lower estuary. Our results suggest that despite the fast mineralization rates, the terrestrial DOC is processed only to a minor extent relative to the pulsed amount entering the estuary. We conclude that the vast quantity of organic carbon delivered to estuaries by TCs transform estuaries from active biogeochemical processing “reactors” of organic carbon to appear more like passive shunts due to the sheer amount of pulsed material rapidly flushed through the estuary.</p>

scholarly journals Assessing branched tetraether lipids as tracers of soil organic carbon transport through the Carminowe Creek catchment (southwest England)

2020 ◽  
Vol 17 (12) ◽  
pp. 3183-3201 ◽  
Author(s):  
Jingjing Guo ◽  
Miriam Glendell ◽  
Jeroen Meersmans ◽  
Frédérique Kirkels ◽  
Jack J. Middelburg ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Membrane Lipids ◽  
Arable Land ◽  
Small Catchment ◽  
Bed Sediments ◽  
Core Sediments ◽  
History Of ◽  
Carbon Dioxide Co2 ◽  
Lake Core

Abstract. Soils represent the largest reservoir of organic carbon (OC) on land. Upon mobilization, this OC is either returned to the atmosphere as carbon dioxide (CO2) or transported and ultimately locked into (marine) sediments, where it will act as a long-term sink of atmospheric CO2. These fluxes of soil OC are, however, difficult to evaluate, mostly due to the lack of a soil-specific tracer. In this study, a suite of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are membrane lipids of soil bacteria, is tested as specific tracers for soil OC from source (soils under arable land, ley, grassland, and woodland) to sink (Loe Pool sediments) in a small catchment located in southwest England (i.e. Carminowe Creek draining into Loe Pool). The analysis of brGDGTs in catchment soils reveals that their distribution is not significantly different across different land use types (p>0.05) and thus does not allow land-use-specific soil contributions to Loe Pool sediments to be traced. Furthermore, the significantly higher contribution of 6-methyl brGDGT isomers in creek sediments (isomerization ratio (IR) = 0.48±0.10, mean ± standard deviation (SD); p<0.05) compared to that in catchment soils (IR = 0.28±0.11) indicates that the initial soil signal is substantially altered by brGDGT produced in situ. Similarly, the riverine brGDGT signal appears to be overwritten by lacustrine brGDGTs in the lake sedimentary record, indicated by remarkably lower methylation of branched tetraethers (MBT5ME′=0.46±0.02 in creek bed sediments and 0.38±0.01 in lake core sediments; p<0.05) and a higher degree of cyclization (DC = 0.23±0.02 in creek bed sediments and 0.32±0.08 in lake core sediments). Thus, in this small catchment, brGDGTs do not allow us to trace soil OC transport. Nevertheless, the downcore changes in the degree of cyclization and the abundance of isoprenoid GDGTs produced by methanogens in the Loe Pool sediment do reflect local environmental conditions over the past 100 years and have recorded the eutrophication history of the lake.

scholarly journals Origin and Pathways of Dissolved Organic Carbon in a Small Catchment in the Lena River Delta

2022 ◽  
Vol 9 ◽  
Author(s):  
Lydia Stolpmann ◽  
Gesine Mollenhauer ◽  
Anne Morgenstern ◽  
Jens S. Hammes ◽  
Julia Boike ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
River Delta ◽  
Aquatic Systems ◽  
The Arctic ◽  
Small Catchment ◽  
Lena River ◽  
Thermokarst Lake ◽  
Doc Concentration ◽  
Lena River Delta

The Arctic is rich in aquatic systems and experiences rapid warming due to climate change. The accelerated warming causes permafrost thaw and the mobilization of organic carbon. When dissolved organic carbon is mobilized, this DOC can be transported to aquatic systems and degraded in the water bodies and further downstream. Here, we analyze the influence of different landscape components on DOC concentrations and export in a small (6.45 km2) stream catchment in the Lena River Delta. The catchment includes lakes and ponds, with the flow path from Pleistocene yedoma deposits across Holocene non-yedoma deposits to the river outlet. In addition to DOC concentrations, we use radiocarbon dating of DOC as well as stable oxygen and hydrogen isotopes (δ18O and δD) to assess the origin of DOC. We find significantly higher DOC concentrations in the Pleistocene yedoma area of the catchment compared to the Holocene non-yedoma area with medians of 5 and 4.5 mg L−1 (p &lt; 0.05), respectively. When yedoma thaw streams with high DOC concentration reach a large yedoma thermokarst lake, we observe an abrupt decrease in DOC concentration, which we attribute to dilution and lake processes such as mineralization. The DOC ages in the large thermokarst lake (between 3,428 and 3,637 14C y BP) can be attributed to a mixing of mobilized old yedoma and Holocene carbon. Further downstream after the large thermokarst lake, we find progressively younger DOC ages in the stream water to its mouth, paired with decreasing DOC concentrations. This process could result from dilution with leaching water from Holocene deposits and/or emission of ancient yedoma carbon to the atmosphere. Our study shows that thermokarst lakes and ponds may act as DOC filters, predominantly by diluting incoming waters of higher DOC concentrations or by re-mineralizing DOC to CO2 and CH4. Nevertheless, our results also confirm that the small catchment still contributes DOC on the order of 1.2 kg km−2 per day from a permafrost landscape with ice-rich yedoma deposits to the Lena River.

Long term brownification process at the Lammi LTER area in Finland

2020 ◽  
Author(s):  
Katri Rankinen ◽  
Maria Holmberg ◽  
Seppo Hellsten ◽  
Lauri Arvola ◽  
Ninni Liukko ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Organic Carbon ◽  
Large Scale ◽  
Organic Soils ◽  
Minor Effect ◽  
Sulphur Deposition ◽  
Water Colour ◽  
Doc Concentration

&lt;p&gt;Browning of surface waters due to increased terrestrial loading of organic carbon is observed in boreal regions. It is explained by large scale changes in ecosystems, including decrease in sulphur deposition that affects soil organic matter solubility, increase in temperature that stimulates export of dissolved organic carbon (DOC) from organic soils, and increase in precipitation and thus runoff. Land use changes and forestry measures are also observed to be one reason for increased transport of DOC. The effects of brownification extend to ecosystem services like water purification, but also freshwater productivity through limiting light penetration and creating more stable thermal stratification. The research question at the Lammi LTER area (Southern Boreal Aquatic and Terrestrial Long-Term Ecological Research Area) was brownification of the lake P&amp;#228;&amp;#228;j&amp;#228;rvi. We studied both past trends of organic carbon loading from catchments and water colour in the lake based on observations since early 1990&amp;#8217;s. We also made simulations of loading for future climate by the physical Persist and INCA models. DOC concentration in the lake was simulated by the physical MyLake model. Simulated DOC concentration was transformed to water colour and light climate of the lake by empirical equations to study the influence on macrophytes (as an indicator of the ecosystem state). In future growing depths might decrease from 2 m to 1.2 m corresponding to observed shift from reference lakes to impacted lakes. Brownification was driven mainly by the change in climate and decay of organic matter in soil, with smaller impact of land use change on organic soil types. Decrease in sulphur deposition had only minor effect on brownification.&lt;/p&gt;

scholarly journals Assessing branched tetraether lipids as tracers of soil organic carbon transport through the Carminowe Creek catchment (southwest England)

2020 ◽  
Author(s):  
Jingjing Guo ◽  
Miriam Glendell ◽  
Jeroen Meersmans ◽  
Frédérique Kirkels ◽  
Jack J. Middelburg ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Membrane Lipids ◽  
Arable Land ◽  
Small Catchment ◽  
Land Use Types ◽  
Tetraether Lipids ◽  
Carbon Dioxide Co2 ◽  
Carbon Transport

Abstract. Soils represent the largest reservoir of organic carbon (OC) on land. Upon mobilization, this OC is either returned to the atmosphere as carbon dioxide (CO2), or transported and ultimately locked into (marine) sediments, where it will act as a long-term sink of atmospheric CO2. These fluxes of soil OC are, however, poorly quantified, mostly due to the lack of a soil-specific tracer. In this study, a suite of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are membrane lipids of soil bacteria, is tested as specific tracers for soil OC from source (soils under arable land, ley, grassland and woodland) to sink (Lake Loe Pool sediments) considering a small catchment located in southwest England (i.e. Carminowe Creek draining into Lake Loe Pool). The analysis of brGDGTs in catchment soils reveals that their distribution is not significantly different across different land use types (p > 0.05), and thus does not allow tracing land use-specific soil contributions to Lake Loe Pool sediments. Furthermore, the significantly higher contribution of 6-methyl brGDGT isomers in creek sediments (isomerization ratio (IR) = 0.48 ± 0.10; mean ± s.d., standard deviation; p 

Soil erosion, dissolved organic carbon and nutrient losses under different land use systems in a small catchment in northern Vietnam

2014 ◽  
Vol 146 ◽  
pp. 314-323 ◽  
Author(s):  
J.-L. Janeau ◽  
L.-C. Gillard ◽  
S. Grellier ◽  
P. Jouquet ◽  
Thi Phuong Quynh Le ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Nutrient Losses ◽  
Small Catchment ◽  
Land Use Systems ◽  
Northern Vietnam

scholarly journals Landscape controls on riverine export of dissolved organic carbon from Great Britain

2021 ◽  
Author(s):  
Jennifer L. Williamson ◽  
Andrew Tye ◽  
Dan J. Lapworth ◽  
Don Monteith ◽  
Richard Sanders ◽  
...  
Keyword(s):  
Land Use ◽  
Great Britain ◽  
Population Density ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Forest Cover ◽  
River Systems ◽  
C Cycle ◽  
Global Land ◽  
Doc Export

AbstractThe dissolved organic carbon (DOC) export from land to ocean via rivers is a significant term in the global C cycle, and has been modified in many areas by human activity. DOC exports from large global rivers are fairly well quantified, but those from smaller river systems, including those draining oceanic regions, are generally under-represented in global syntheses. Given that these regions typically have high runoff and high peat cover, they may exert a disproportionate influence on the global land–ocean DOC export. Here we describe a comprehensive new assessment of the annual riverine DOC export to estuaries across the island of Great Britain (GB), which spans the latitude range 50–60° N with strong spatial gradients of topography, soils, rainfall, land use and population density. DOC yields (export per unit area) were positively related to and best predicted by rainfall, peat extent and forest cover, but relatively insensitive to population density or agricultural development. Based on an empirical relationship with land use and rainfall we estimate that the DOC export from the GB land area to the freshwater-seawater interface was 1.15 Tg C year−1 in 2017. The average yield for GB rivers is 5.04 g C m−2 year−1, higher than most of the world’s major rivers, including those of the humid tropics and Arctic, supporting the conclusion that under-representation of smaller river systems draining peat-rich areas could lead to under-estimation of the global land–ocean DOC export. The main anthropogenic factor influencing the spatial distribution of GB DOC exports appears to be upland conifer plantation forestry, which is estimated to have raised the overall DOC export by 0.168 Tg C year−1. This is equivalent to 15% of the estimated current rate of net CO2 uptake by British forests. With the UK and many other countries seeking to expand plantation forest cover for climate change mitigation, this ‘leak in the ecosystem’ should be incorporated in future assessments of the CO2 sequestration potential of forest planting strategies.

scholarly journals Dynamics of soil organic carbon in the steppes of Russia and Kazakhstan under past and future climate and land use

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Susanne Rolinski ◽  
Alexander V. Prishchepov ◽  
Georg Guggenberger ◽  
Norbert Bischoff ◽  
Irina Kurganova ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Organic Carbon ◽  
Land Use Change ◽  
Soil Organic Carbon ◽  
Arable Land ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Scenarios ◽  
The Impact

AbstractChanges in land use and climate are the main drivers of change in soil organic matter contents. We investigated the impact of the largest policy-induced land conversion to arable land, the Virgin Lands Campaign (VLC), from 1954 to 1963, of the massive cropland abandonment after 1990 and of climate change on soil organic carbon (SOC) stocks in steppes of Russia and Kazakhstan. We simulated carbon budgets from the pre-VLC period (1900) until 2100 using a dynamic vegetation model to assess the impacts of observed land-use change as well as future climate and land-use change scenarios. The simulations suggest for the entire VLC region (266 million hectares) that the historic cropland expansion resulted in emissions of 1.6⋅ 1015 g (= 1.6 Pg) carbon between 1950 and 1965 compared to 0.6 Pg in a scenario without the expansion. From 1990 to 2100, climate change alone is projected to cause emissions of about 1.8 (± 1.1) Pg carbon. Hypothetical recultivation of the cropland that has been abandoned after the fall of the Soviet Union until 2050 may cause emissions of 3.5 (± 0.9) Pg carbon until 2100, whereas the abandonment of all cropland until 2050 would lead to sequestration of 1.8 (± 1.2) Pg carbon. For the climate scenarios based on SRES (Special Report on Emission Scenarios) emission pathways, SOC declined only moderately for constant land use but substantially with further cropland expansion. The variation of SOC in response to the climate scenarios was smaller than that in response to the land-use scenarios. This suggests that the effects of land-use change on SOC dynamics may become as relevant as those of future climate change in the Eurasian steppes.

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