scholarly journals The Spatiotemporal Evolution of Storm Pulse Particulate Organic Carbon in a Low Gradient, Agriculturally Dominated Watershed

2021 ◽  
Vol 3 ◽  
Author(s):  
Neal E. Blair ◽  
Elmer Arthur Bettis ◽  
Timothy R. Filley ◽  
Jessie A. Moravek ◽  
A. N. Thanos Papanicolaou ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Heavy Precipitation ◽  
Small Contribution ◽  
Storm Events ◽  
Stream Network ◽  
Carbon And Nitrogen ◽  
Row Crop ◽  
Agricultural Stream ◽  
Changes Over Time

Streams and rivers integrate and transport particulate organic carbon (POC) from an array of aquatic and terrestrial sources. Storm events greatly accelerate the transport of POC. The sequences by which individual POC inputs are mobilized and transported are not well-documented but are predicted to be temporally transient and spatially dependent because of changes in forcing functions, such as precipitation, discharge, and watershed morphology. In this study, the 3rd−4th order agricultural stream network, Clear Creek in Iowa, U.S.A., was sampled at a nested series of stations through storm events to determine how suspended POC changes over time and with distance downstream. Carbon and nitrogen stable isotope ratios were used to identify changes in POC. A temporal sequence of inputs was identified: in-channel algal production prior to heavy precipitation, row crop surface soils mobilized during peak precipitation, and material associated with the peak hydrograph that is hypothesized to be an integrated product from upstream. Tile drains delivered relatively 13C- and 15N-depleted particulate organic carbon that is a small contribution to the total POC inventory in the return to baseflow. The storm POC signal evolved with passage downstream, the principal transformation being the diminution of the early flush surface soil peak in response to a loss of connectivity between the hillslope and channel. Bank erosion is hypothesized to become increasingly important as the signal propagates downstream. The longitudinal evolution of the POC signal has implications for C-budgets associated with soil erosion and for interpreting the organic geochemical sedimentary record.

scholarly journals Macrobenthic assemblage structure and organismal stoichiometry control faunal processing of particulate organic carbon and nitrogen in oxygen minimum zone sediments

2012 ◽  
Vol 9 (3) ◽  
pp. 993-1006 ◽  
Author(s):  
W. R. Hunter ◽  
L. A. Levin ◽  
H. Kitazato ◽  
U. Witte
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Oxygen Minimum Zone ◽  
Oxygen Availability ◽  
Assemblage Structure ◽  
Sediment Geochemistry ◽  
Sea Floor ◽  
Carbon And Nitrogen ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The Arabian Sea oxygen minimum zone (OMZ) impinges on the western Indian continental margin between 150 and 1500 m, causing gradients in oxygen availability and sediment geochemistry at the sea floor. Oxygen availability and sediment geochemistry are important factors structuring macrofaunal assemblages in marine sediments. However, relationships between macrofaunal assemblage structure and sea-floor carbon and nitrogen cycling are poorly understood. We conducted in situ 13C:15N tracer experiments in the OMZ core (540 m [O2] = 0.35 μmol l–1) and lower OMZ boundary (800–1100 m, [O2] = 2.2–15.0 μmol l–1) to investigate how macrofaunal assemblage structure, affected by different oxygen levels, and C:N coupling influence the fate of particulate organic matter. No macrofauna were present in the OMZ core. Within the OMZ boundary, relatively high abundance and biomass resulted in the highest macrofaunal assimilation of particulate organic carbon (POC) and nitrogen (PON) at the lower oxygen 800 m stations ([O2] = 2.2–2.36 μmol l–1). At these stations the numerically dominant cirratulid polychaetes exhibited greatest POC and PON uptake. By contrast, at the higher oxygen 1100 m station ([O2] = 15.0 μmol l–1) macrofaunal C and N assimilation was lower, with POC assimilation dominated by one large solitary ascidian. Macrofaunal POC and PON assimilation were influenced by changes in oxygen availability, and significantly correlated to differences in macrofaunal assemblage structure between stations. However, macrofaunal feeding responses were ultimately characterised by preferential organic nitrogen assimilation, relative to their internal C:N budgets.

scholarly journals Variation pattern of particulate organic carbon and nitrogen in oceans and inland waters

2017 ◽  
Author(s):  
Changchun Huang ◽  
Lin Yao ◽  
Hao Yang ◽  
Chen Lin ◽  
Tao Huang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Inland Waters ◽  
Mean Values ◽  
Inland Water ◽  
Carbon And Nitrogen ◽  
Average Value ◽  
The Mean ◽  
The Relationship ◽  
Global Carbon

Abstract. We examined the relationship between, and variations in, particulate organic carbon (POC) and particulate organic nitrogen (PON) based on previously acquired ocean and inland water data. Some new points were found beside the traditional latitude, depth and temperature dependence of POC, PON and POC/PON. The global average value of POC/PON (7.54±3.82) is higher than the Redfield ratio (6.63). The mean values of POC/PON in south and north hemisphere are 7.40±3.83 and 7.80±3.92, respectively. The high values of POC/PON appeared between 80° N~90° N (12.2±7.5) and 70° N~80° N (9.4±6.4), and relatively low POC/PON were found from 20 °N (6.6±2.8) to 40 °N (6.7±2.7). The latitudinal dependency of POC/PON in the northern hemisphere is much stronger than in the southern hemisphere. Variations of POC/PON in inland water also showed similar latitude-dependency of POC/PON in ocean water, but significantly regulated by lake’s morphology, trophic state and climate, etc. factors. Higher POC and PON could be expected in the coastal water, while POC/PON significantly increased from 6.89±2.38 to 7.59±4.22 in north hemisphere with the increasing rate of 0.0024/km. The coupling relationship between POC and PON in oceans is much stronger than in inland waters. Variations in POC, PON and POC/PON in inland waters should receive more attention due to the importance of these values to global carbon and nitrogen cycles and the indeterminacy of the relationship between POC and PON.

Proteins: Amino Acids and Amines

2011 ◽  
Author(s):  
Thomas S. Bianchi ◽  
Elizabeth A. Canuel
Keyword(s):  
Amino Acids ◽  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Particulate Organic Carbon ◽  
Nitrogen Cycle ◽  
Organic Nitrogen ◽  
Building Blocks ◽  
Marine Organisms ◽  
Carbon And Nitrogen

This chapter discusses proteins, which make up approximately 50% of organic matter and contain about 85% of the organic nitrogen in marine organisms. Peptides and proteins comprise an important fraction of the particulate organic carbon (13–37%) and particulate organic nitrogen (30–81%), as well as dissolved organic nitrogen (5–20%) and dissolved organic carbon (3–4%) in oceanic and coastal waters. In sediments, proteins account for approximately 7 to 25% of organic carbon and an estimated 30 to 90% of total nitrogen. Amino acids are the basic building blocks of proteins. This class of compounds is essential to all organisms and represents one of the most important components in the organic nitrogen cycle. Amino acids represent one of the most labile pools of organic carbon and nitrogen.

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