Chemical concentrations of overland flow and throughflow from pastures on sloping texture-contrast soils

2001 ◽  
Vol 52 (2) ◽  
pp. 211 ◽  
Author(s):  
J. W. Cox ◽  
A. Pitman
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Overland Flow ◽  
South Australia ◽  
Annual Rainfall ◽  
Nitrate Losses ◽  
Nitrate Concentrations ◽  
Texture Contrast ◽  
Carbon Losses ◽  
Carbon Concentrations

Shallow drains are increasingly being installed to allow cropping and improve pastures in soils prone to waterlogging. Concentrations and loads of a range of chemicals including nitrate, dissolved organic carbon, and phosphorus were measured in overland flow and throughflow (drainage) from grazed standard and improved pastures in a region of the Adelaide Hills, South Australia, with 544 mm annual rainfall. In low to average rainfall years, nitrate losses from standard pastures were up to 21 times higher in throughflow (up to 0.3 kg/ha.year) than in overland flow. Dissolved organic carbon losses from standard pastures were also highest in throughflow (up to 3.5 kg/ha.year) as were loads of Na, Cl, Al, Fe, K, and Mg. Total P loads were higher in throughflow (0.15 kg/ha.year) than in overland flow. However, P concentrations in throughflow were similar to overland flow (up to 0.5 mg/L). Chemical loads from improved pastures were higher in throughflow than in overland flow. Nitrate, dissolved organic carbon, and P losses from improved pastures were up to 0.8, 8.5, and 0.1 kg/ha.year, respectively. Improved pastures had higher dissolved organic carbon concentrations (14 mg/L) and nitrate concentrations than either the standard pastures or those reported off some dairy pastures in the region. Nitrate concentrations were highest in throughflow in subsurface tube drains below the improved pastures (up to 67 mg/L).

Carbon and phosphorus losses from dairy pasture in South Australia

Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 969 ◽  
Author(s):  
N. K. Fleming ◽  
J. W. Cox
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Overland Flow ◽  
Dissolved Inorganic Carbon ◽  
South Australia ◽  
Annual Rainfall ◽  
Carbon Loss ◽  
Dissolved Carbon ◽  
Time Of Year ◽  
Phosphorus Losses

Runoff (overland flow and A/B horizon interflow) was measured from 2 grazed dairy pastures at Flaxley, South Australia, from 1996 to 1998. Runoff ranged from 0.4% to 10% of annual rainfall and >90% of this was overland flow. Phosphorus and carbon were measured in runoff. As much as 2.3 kg/ha of phosphorus and 10.7 kg/ha of total dissolved carbon were lost from the subcatchments in the wettest year. Over the study period, 98% of total phosphorus and 86% of total dissolved carbon were lost in overland flow. Around 45% of phosphorus was dissolved and 69% of total dissolved carbon was dissolved organic carbon. The proportion of phosphorus present in the particulate form decreased during each runoff season, and was highest in the wettest year. There was no consistent trend in the proportion of total dissolved carbon present as dissolved organic carbon because the factors found to affect dissolved organic carbon loss were different from those affecting dissolved inorganic carbon loss. Predictive relationships based on factors such as the time of year when the storm occurred and runoff volume have been developed from the 3 years of data and they explain a high proportion of variability of phosphorus and carbon loads.

Seasonal changes in pathways of dissolved organic carbon through a hillslope soil (Xeralf) with contrasting texture

Soil Research ◽  
1992 ◽  
Vol 30 (4) ◽  
pp. 465 ◽  
Author(s):  
DJ Chittleborough ◽  
KRJ Smettem ◽  
E Cotsaris ◽  
FW Leaney
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Overland Flow ◽  
Podzolic Soil ◽  
Marked Decrease ◽  
Soil Surface ◽  
Storm Events ◽  
Dry Period ◽  
Doc Concentration ◽  
Texture Contrast

The pathways of dissolved organic carbon (DOC) through a podzolic soil (Xeralf) with strong texture contrast are described. During winter, most of the DOC passes through macropores in the profile and flows laterally through the B horizons. During summer the presence of dry, hydrophobic organic matter on the soil surface and the A1 horizon causes DOC to flow overland. DOC concentrations vary seasonally. Highest concentrations are measured during summer overland flow. For all horizons, the longer the dry period the greater the DOC concentration in the subsequent flow. During storm events there is a marked flushing effect in the B horizons but in the A horizon and the surface, DOC concentrations tend to rise. There was a marked decrease in DOC concentration in flow from the B3 compared to the upper horizons. This may be due to adsorption by fine clays lining the macropores.

Water quality of gully drainage from texture-contrast soils in the Adelaide Hills in low rainfall years

Soil Research ◽  
2000 ◽  
Vol 38 (5) ◽  
pp. 959 ◽  
Author(s):  
J. W. Cox ◽  
R. Ashley
Keyword(s):  
Overland Flow ◽  
Environmental Concern ◽  
South Australia ◽  
Drainage Water ◽  
Agricultural Catchments ◽  
Environmental Guidelines ◽  
Texture Contrast ◽  
Carbon Concentrations ◽  
Dissolved Form

The volume and quality of drainage water in a gully cutting through a series of waterlogged, saline, sodic, and sulfidic Xeralfs in the Adelaide Hills, South Australia, was studied over 3 years. This was done to gain a better perspective of the relative quantities of contaminants being exported from agricultural catchments in low rainfall agricultural environments. It was found that in low rainfall years, when little overland flow occurs and gully flow is predominantly groundwater discharge and throughflow, loads in the drainage gully were up to 41 kg/ha.year of sodium and 2 kg/ha.year of sulfur. Losses of sulfur, magnesium, and calcium followed a similar trend to sodium losses and could be predicted with significant accuracy. The losses of phosphorus (5–7 g/ha.year) and nitrate (<2 g/ha.year) were less predictable. Phosphorus concentrations were of environmental concern each year whereas nitrate concentrations were only above environmental guidelines in the driest year. All phosphorus in the gully drainage was transported in the dissolved form. Dissolved organic carbon concentrations were usually >26 mg/L and will be costly to treat if used for public water supply.

Pathways of phosphorus, nitrogen, and carbon movement over and through texturally differentiated soils, South Australia

Soil Research ◽  
1999 ◽  
Vol 37 (4) ◽  
pp. 679 ◽  
Author(s):  
D. J. Chittleborough ◽  
J. W. Cox ◽  
D. P. Stevens
Keyword(s):  
Organic Carbon ◽  
Overland Flow ◽  
South Australia ◽  
Catchment Management ◽  
Catchment Scale ◽  
Through Flow ◽  
Close Proximity ◽  
Significant Loading ◽  
Restrict Movement ◽  
Texture Contrast

One method for preventing the degradation of water supplies through contamination with phosphorus (P), nitrate (NO3), and dissolved organic carbon (DOC) is to restrict movement of these contaminants from the catchment into water bodies. The purpose of the study was to quantify and characterise the proportion of NO3, P, and DOC moving from duplex soils by overland flow and through-flow on a sub-catchment scale, and to characterise soil properties that influence their movement. Two sites in the Adelaide Hills (South Australia) with contrasting duplex soils were instrumented to collect overland flow and through-flow from the soils A and B horizon. Each site contained 2 sub-catchments in close proximity. Sub-catchments were well defined by the natural topography sloping from hillcrest to a stream headwater. Soil type, especially the degree of texture contrast, the macroporosity, and the proportion of clay in the B horizon, had a large influence on the pathways of water, and therefore P, DOC, and NO3 movement. Environmentally significant concentrations of P (>0�1 mg/L) and NO3-N (>0�5 mg/L) moved overland and through these soils in 1997. High DOC loads (25 mg/L), which would also impact on water treatment costs, moved through some soils. Significant loading of P moved through and over soils in both dissolved (0�5 mg/L) and particulate (0�3 mg/L) forms. Consequently, through-flow cannot be ignored as a contributor to P in streams and both dissolved and particulate P must be measured under these conditions to define the full impact of P. The findings from this research have implications for research on catchment management to restrict DOC and nutrient movement into waterways.

Dissolved organic carbon concentrations and fluxes along the Moisie River, Quebec

1990 ◽  
Vol 24 (1) ◽  
pp. 35-42 ◽  
Author(s):  
T. E. FORD ◽  
S. A. FORD ◽  
M. A. LOCK ◽  
R. J. NAIMAN
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Carbon Concentrations

scholarly journals Carbon losses from pyrolysed and original wood in a forest soil under natural and increased N deposition

2014 ◽  
Vol 11 (18) ◽  
pp. 5199-5213 ◽  
Author(s):  
B. Maestrini ◽  
S. Abiven ◽  
N. Singh ◽  
J. Bird ◽  
M. S. Torn ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Forest Soil ◽  
N Deposition ◽  
Main Process ◽  
N Availability ◽  
N Losses ◽  
Mineral N ◽  
C Cycling ◽  
Carbon Losses

Abstract. Pyrogenic organic matter (PyOM) plays an important role as a stable carbon (C) sink in the soils of terrestrial ecosystems. However, uncertainties remain about in situ turnover rates of fire-derived PyOM in soil, the main processes leading to PyOM-C and nitrogen (N) losses from the soil, and the role of N availability on PyOM cycling in soils. We measured PyOM and native soil organic carbon losses from the soil as carbon dioxide and dissolved organic carbon (DOC) using additions of highly 13C-labelled PyOM (2.03 atom %) and its precursor pinewood during 1 year in a temperate forest soil. The field experiment was carried out under ambient and increased mineral N deposition (+60 kg N-NH4NO3 ha−1 year−1). The results showed that after 1 year: (1) 0.5% of PyOM-C and 22% of wood-C were mineralized as CO2, leading to an estimated turnover time of 191 and 4 years, respectively; (2) the quantity of PyOM and wood lost as dissolved organic carbon was negligible (0.0004 ± 0.0003% and 0.022 ± 0.007% of applied-C, respectively); and (3) N additions decreased cumulative PyOM mineralization by 43%, but did not affect cumulative wood mineralization and did not affect the loss of DOC from PyOM or wood. We conclude that mineralization to CO2 was the main process leading to PyOM losses during the first year of mineralization in a forest soil, and that N addition can decrease PyOM-C cycling, while added N showed no effect on wood C cycling.

scholarly journals Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5984 ◽  
Author(s):  
Nataly Carolina Guevara Campoverde ◽  
Christiane Hassenrück ◽  
Pier Luigi Buttigieg ◽  
Astrid Gärdes
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Dissolved Organic Carbon ◽  
Bacterial Communities ◽  
Carbon Pools ◽  
Aggregate Formation ◽  
Galapagos Archipelago ◽  
Carbon Concentrations ◽  
Bacterioplankton Communities

Bacteria play a crucial role in the marine carbon cycle, contributing to the production and degradation of organic carbon. Here, we investigated organic carbon pools, aggregate formation, and bacterioplankton communities in three contrasting oceanographic settings in the Galapagos Archipelago. We studied a submarine CO2 vent at Roca Redonda (RoR), an upwelling site at Bolivar Channel (BoC) subjected to a weak El Niño event at the time of sampling in October 2014, as well as a site without volcanic or upwelling influence at Cowley Islet (CoI). We recorded physico-chemical parameters, and quantified particulate and dissolved organic carbon, transparent exopolymeric particles, and the potential of the water to form larger marine aggregates. Free-living and particle-attached bacterial communities were assessed via 16S rRNA gene sequencing. Both RoR and BoC exhibited temperatures elevated by 1–1.5 °C compared to CoI. RoR further experienced reduced pH between 6.8 and 7.4. We observed pronounced differences in organic carbon pools at each of the three sites, with highest dissolved organic carbon concentrations at BoC and RoR, and highest particulate organic carbon concentrations and aggregate formation at BoC. Bacterioplankton communities at BoC were dominated by opportunistic copiotrophic taxa, such as Alteromonas and Roseobacter, known to thrive in phytoplankton blooms, as opposed to oligotrophic taxa dominating at CoI, such as members of the SAR11 clade. Therefore, we propose that bacterial communities were mainly influenced by the availability of organic carbon at the investigated sites. Our study provides a comprehensive characterization of organic carbon pools and bacterioplankton communities, highlighting the high heterogeneity of various components of the marine carbon cycle around the Galapagos Archipelago.

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