scholarly journals Long-term Trends of Organic Carbon Concentrations in Freshwaters: Strengths and Weaknesses of Existing Evidence

Water ◽  
2014 ◽  
Vol 6 (5) ◽  
pp. 1360-1418 ◽  
Author(s):  
Montserrat Filella ◽  
Juan Rodríguez-Murillo
Keyword(s):  
Organic Carbon ◽  
Long Term Trends ◽  
Carbon Concentrations

Effects of agricultural management on dermosols in northern Tasmania

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 65 ◽  
Author(s):  
W. E. Cotching ◽  
J. Cooper ◽  
L. A. Sparrow ◽  
B. E. McCorkell ◽  
W. Rowley
Keyword(s):  
Organic Carbon ◽  
Microbial Biomass Carbon ◽  
Aggregate Stability ◽  
Infiltration Rate ◽  
Penetration Resistance ◽  
Agricultural Management ◽  
Structural Development ◽  
Laboratory Techniques ◽  
Carbon Concentrations

Attributes of 15 Tasmanian dermosols were assessed using field and laboratory techniques to determine changes associated with 3 typical forms of agricultural management: long-term pasture, cropping with shallow tillage using discs and tines, and cropping (including potatoes) with more rigorous and deeper tillage including deep ripping and powered implements. Soil organic carbon in the surface 75 mm was 7.0% under long-term pasture compared with 4.3% and 4.2% in cropped paddocks. Microbial biomass carbon concentrations were 217 mg/kg, 161 mg/kg, and 139 mg/kg, respectively. These differences were negatively correlated with the number of years cropped. Greater bulk densities were found in the surface layer of cropped paddocks but these were not associated with increased penetration resistance or decreased infiltration rate and are unlikely to impede root growth. Long-term pasture paddocks showed stronger structural development and had smaller clods than cropped paddocks. Vane shear strength and penetration resistance were lower in cropped paddocks than under long-term pasture. Many soil attributes showed no significant differences associated with management. Including potatoes in the rotation did not appear to affect these dermosols, which indicates a degree of robustness in these soils. clay loams, organic carbon, soil strength, aggregate stability, land management, cropping.

scholarly journals Dissolved organic carbon concentrations vary with season and land use – investigations from two fens in Northeastern Germany over two years

2014 ◽  
Vol 11 (5) ◽  
pp. 7079-7111 ◽  
Author(s):  
M. Schwalm ◽  
J. Zeitz
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Environmental Concern ◽  
Doc Export ◽  
Doc Concentration ◽  
Agricultural Use ◽  
Northeastern Germany ◽  
Carbon Concentrations ◽  
Discharge Measurements

Abstract. The rising export of dissolved organic carbon (DOC) from peatlands during the last 20 years is of great environmental concern, as DOC harms drinking water quality and diminishes the carbon storage of peatlands. Lack of knowledge particularly exists for fens. The aim of our study was to determine DOC concentrations at an agriculturally used fen and a rewetted fen throughout the year. We measured DOC concentrations in ditch water of these fens in 2011 and 2012. Furthermore, discharge measurements were condcucted to detect DOC export. Overall DOC concentrations at our agriculturally used site and at our rewetted site were 35 mg L−1 and 26 mg L−1 (median), respectively. The maximum DOC concentration at our agriculturally used site was twice as high as at the rewetted site (134 mg L−1 vs. 61 mg L−1). Annual DOC export was calculated for the rewetted site, amounting to 200 kg C ha−1 on average. Our results suggest that rewetting of degraded fens reduces DOC export in the long-term, while agricultural use of fens leads to enhanced decomposition and thus, elevates DOC export.

scholarly journals Trends in soil solution dissolved organic carbon (DOC) concentrations across European forests

2016 ◽  
Author(s):  
M. Camino-Serrano ◽  
E. Graf Pannatier ◽  
S. Vicca ◽  
S. Luyssaert ◽  
M. Jonard ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Atmospheric Deposition ◽  
Soil Solution ◽  
Surface Waters ◽  
European Forests ◽  
Icp Forests ◽  
Level Ii ◽  
Long Term Trends

Abstract. Dissolved organic carbon (DOC) in soil solution is connected to DOC in surface waters through hydrological flows. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site-studies has failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result from acidification recovery. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analys is at two levels: 1) to the entire European dataset and 2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC across Europe with temporal slopes of soil solution DOC ranging between −16.8 % yr−1 and +23 % yr−1 (median= +0.4 % yr−1). The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing DOC concentrations with increasing mean nitrate (NO3−) deposition and decreasing DOC concentrations with decreasing me an sulphate (SO42−) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduct ion of SO42− deposition could be confirmed in N-poorer forests, in agreement with observations in surface waters, this was not the case in N-richer forests. In conclusion, long-term trends of soil solution DOC reflected the interactions between controls acting at local (soil and vegetation properties) and regional (atmospheric deposition of SO42− and inorganic N) scales.

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