Open water metabolism and dissolved organic carbon in response to environmental watering in a lowland river–floodplain complex

2016 ◽  
Vol 67 (9) ◽  
pp. 1346 ◽  
Author(s):  
Todd A. Wallace ◽  
Deborah Furst
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Food Webs ◽  
Ecosystem Respiration ◽  
Open Water ◽  
Relative Role ◽  
Eastern Australia ◽  
Return Flows ◽  
Receiving Waters ◽  
The Impact

The relative importance of autochthonous and allochthonous organic material in fuelling ecosystem metabolism is increasingly understood for some river systems. However, in south-eastern Australia, the majority of studies have been conducted during low flows when the supply of allochthonous carbon was limited. Consequently, the importance of episodic inputs of terrestrially derived material in supporting these food webs remains poorly understood. We assessed the influence of return flows from two different scales of environmental watering actions on dissolved organic carbon and open-water productivity in receiving waters adjacent to the watered area. For the wetland-scale event, gross primary productivity and ecosystem respiration increased in the receiving waters during the period of return flows. During the floodplain-scale watering, differences were observed among sites. Within the managed inundation zone, values for net ecosystem productivity switched from near zero during the baseline to strongly negative during the impact period, whereas values at the river sites were either near zero or positive. The results contribute to our understanding of the relative role of allochthonous material in supporting aquatic food webs in lowland rivers, and demonstrate potential for watering actions to have a positive influence on riverine productivity during periods of low water availability.

scholarly journals The impact of dissolved organic carbon and bacterial respiration on pCO2 in experimental sea ice

2016 ◽  
Vol 141 ◽  
pp. 153-167 ◽  
Author(s):  
J. Zhou ◽  
M. Kotovitch ◽  
H. Kaartokallio ◽  
S. Moreau ◽  
J.-L. Tison ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Sea Ice ◽  
Dissolved Organic Carbon ◽  
Bacterial Respiration ◽  
The Impact

scholarly journals Relative importance of CO2 recycling and CH4 pathways in lake food webs along a dissolved organic carbon gradient

2006 ◽  
Vol 51 (4) ◽  
pp. 1602-1613 ◽  
Author(s):  
Jay T. Lennon ◽  
Anthony M. Faiia ◽  
Xiahong Feng ◽  
Kathryn L. Cottingham
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Food Webs ◽  
Relative Importance ◽  
Co2 Recycling

scholarly journals Effects of Grazing Pattern on Ecosystem Respiration and Methane Flux in a Sown Pasture in Inner Mongolia, China

Atmosphere ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Baoling Mei ◽  
Hongyu Yue ◽  
Xunhua Zheng ◽  
William McDowell ◽  
Qingshan Zhao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Temperature ◽  
Inner Mongolia ◽  
Nitrate Nitrogen ◽  
Ecosystem Respiration ◽  
Ammonium Nitrogen ◽  
Agricultural Practice ◽  
Ch4 Flux

The establishment of sown pasture is an important agricultural practice in many landscapes. Although both native grassland and sown pasture play a key role in the global carbon cycle, due to lack of data and field experiments, our understanding of grassland CH4 fluxes and CO2 emissions remains limited, especially when it comes to sown pasture. We measured ecosystem respiration and CH4 fluxes in response to a variety of potential drivers (soil temperature, soil moisture, ammonium nitrogen, nitrate nitrogen and dissolved organic carbon) in CG (continuous grazing), RG (rotational grazing) and UG (ungrazed) plots in sown grassland for one year in Inner Mongolia. Fluxes of CH4 and ecosystem respiration were measured using static opaque chambers and gas chromatography. Grazing significantly reduced ecosystem respiration (p < 0.01), and grazing pattern significantly influenced respiration in CG and RG plots (p < 0.01). We find that the sown grassland is a net sink for atmospheric CH4. No influence of grazing pattern was observed on CH4 flux in CG, RG and UG (p > 0.05). Soil temperature is the most important factor influencing ecosystem respiration and CH4 flux in the sown grassland, with soil moisture playing a secondary role to soil temperature. Variation in levels of ammonium nitrogen, nitrate nitrogen and dissolved organic carbon had little influence on ecosystem respiration or CH4 flux (except in UG plots). The values obtained for ecosystem respiration of grasslands have a large uncertainty range, which may be due to spatial variability as well as differences in research methods. Mean CH4 fluxes measured only during the growing season were much higher than the annual mean CH4 fluxes.

scholarly journals Rapid accretion of dissolved organic carbon in the springs of Florida: the most organic-poor natural waters

2010 ◽  
Vol 7 (12) ◽  
pp. 4051-4057 ◽  
Author(s):  
C. M. Duarte ◽  
Y. T. Prairie ◽  
T. K. Frazer ◽  
M. V. Hoyer ◽  
S. K. Notestein ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Primary Production ◽  
Natural Waters ◽  
Gross Primary Production ◽  
Spring Discharge ◽  
High Discharge ◽  
Discharge Rates ◽  
Receiving Waters ◽  
Flowing Waters

Abstract. The concentration of dissolved organic carbon (DOC) in groundwater emanating as spring discharge at several locations in Florida, USA and the net increase in DOC in the downstream receiving waters were measured as part of a larger investigation of carbon dynamics in flowing waters. Springs with high discharge (>2.8 m3 s−1) were found to be the most organic-poor natural waters yet reported (13 ± 1.6 μmol C L−1), while springs with lesser discharge exhibited somewhat higher DOC concentrations (values ranging from 30 to 77 μmol C L−1). DOC concentrations increased rapidly downstream from the point of spring discharge, with the calculated net areal input rate of DOC ranging from 0.04 to 1.64 mol C m−2 d−1 across springs. Rates of DOC increase were generally greater in those springs with high discharge rates. These input rates compare favorably with values reported for gross primary production in these macrophyte-dominated spring systems, assuming that 17% of macrophyte primary production is lost, on average, as DOC. The measures reported here are possible only because of the remarkably low DOC levels in the up-surging groundwaters and the short residency times of the water in the spring-runs themselves.

The impact of nitrogen amendment and crop growth on dissolved organic carbon in soil solution

2016 ◽  
Vol 13 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Xiao-guo Wang ◽  
Chang-sheng Li ◽  
Yong Luo ◽  
Ke-ke Hua ◽  
Ming-hua Zhou
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Solution ◽  
Crop Growth ◽  
Nitrogen Amendment ◽  
The Impact

scholarly journals Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

2016 ◽  
Vol 13 (6) ◽  
pp. 1863-1875 ◽  
Author(s):  
Zahra Thomas ◽  
Benjamin W. Abbott ◽  
Olivier Troccaz ◽  
Jacques Baudry ◽  
Gilles Pinay
Keyword(s):  
Water Quality ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Water Chemistry ◽  
Human Disturbance ◽  
Nutrient Dynamics ◽  
Agricultural Activity ◽  
Agricultural Catchments ◽  
The Impact ◽  
The Relationship

Abstract. Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43−) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent catchment buffering capacity and the probability of human disturbance provides a useful perspective for evaluating vulnerability of aquatic ecosystems and for managing systems to maintain agricultural production while minimizing leakage of nutrients.

scholarly journals Rapid accretion of dissolved organic carbon in the Springs of Florida: the most organic-poor natural waters

2010 ◽  
Vol 7 (4) ◽  
pp. 5253-5267
Author(s):  
C. M. Duarte ◽  
R. Martínez ◽  
Y. T. Prairie ◽  
T. K. Frazer ◽  
M. V. Hoyer ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Primary Production ◽  
Natural Waters ◽  
Gross Primary Production ◽  
Spring Discharge ◽  
High Discharge ◽  
Discharge Rates ◽  
Receiving Waters ◽  
Flowing Waters

Abstract. The concentration of dissolved organic carbon (DOC) in groundwater emanating as spring discharge at several locations in Florida, USA, and the net rate of DOC increase in the downstream receiving waters were measured as part of a larger investigation of carbon dynamics in flowing waters. Springs with high discharge (>2.8 m3 s−1) were found to be the most organic-poor natural waters yet reported (13 ±1.6 μmol C L−1), while springs with lesser discharge exhibited somewhat higher DOC concentrations (values ranging from 30 to 77 μmol C L−1). DOC concentrations increased rapidly downstream from the point of spring discharge, with the calculated net areal input rate of DOC ranging from 0.04 to 1.64 mol C m−2 d−1 across springs. Rates of DOC increase were generally greater in those springs with high discharge rates. These input rates compare favorably with values reported for gross primary production in these macrophyte-dominated spring systems, assuming that 17% of macrophyte primary production is lost, on average, as DOC. The measures reported here are possible only because of the remarkably low DOC levels in the up-surging groundwaters and the short residency times of the water in the spring-runs themselves.

scholarly journals The effect of drought on dissolved organic carbon (DOC) release from peatland soil and vegetation sources

2017 ◽  
Vol 14 (11) ◽  
pp. 2891-2902 ◽  
Author(s):  
Jonathan P. Ritson ◽  
Richard E. Brazier ◽  
Nigel J. D. Graham ◽  
Chris Freeman ◽  
Michael R. Templeton ◽  
...  
Keyword(s):  
Water Treatment ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Unit Weight ◽  
Catchment Management ◽  
Litter Layer ◽  
Peat Soils ◽  
Drought Tolerant ◽  
Doc Production ◽  
The Impact

Abstract. Drought conditions are expected to increase in frequency and severity as the climate changes, representing a threat to carbon sequestered in peat soils. Downstream water treatment works are also at risk of regulatory compliance failures and higher treatment costs due to the increase in riverine dissolved organic carbon (DOC) often observed after droughts. More frequent droughts may also shift dominant vegetation in peatlands from Sphagnum moss to more drought-tolerant species. This paper examines the impact of drought on the production and treatability of DOC from four vegetation litters (Calluna vulgaris, Juncus effusus, Molinia caerulea and Sphagnum spp.) and a peat soil. We found that mild droughts caused a 39.6 % increase in DOC production from peat and that peat DOC that had been exposed to oxygen was harder to remove by conventional water treatment processes (coagulation/flocculation). Drought had no effect on the amount of DOC production from vegetation litters; however large variation was observed between typical peatland species (Sphagnum and Calluna) and drought-tolerant grassland species (Juncus and Molinia), with the latter producing more DOC per unit weight. This would therefore suggest the increase in riverine DOC often observed post-drought is due entirely to soil microbial processes and DOC solubility rather than litter layer effects. Long-term shifts in species diversity may, therefore, be the most important impact of drought on litter layer DOC flux, whereas pulses related to drought may be observed in peat soils and are likely to become more common in the future. These results provide evidence in support of catchment management which increases the resilience of peat soils to drought, such as ditch blocking to raise water tables.

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