An Evaluation of Temporal Changes in Sediment Accumulation and Impacts on Carbon Burial in Mobile Bay, Alabama, USA

2013 ◽  
Vol 37 (5) ◽  
pp. 1092-1106 ◽  
Author(s):  
Christopher G. Smith ◽  
Lisa E. Osterman
Keyword(s):  
Sediment Accumulation ◽  
Temporal Changes ◽  
Mobile Bay ◽  
Carbon Burial

Recent sediments, sediment accumulation and carbon burial at Goban Spur, N.W. European Continental Margin (47–50°N)

1998 ◽  
Vol 42 (1-4) ◽  
pp. 5-35 ◽  
Author(s):  
Tj.C.E. van Weering ◽  
I.R. Hall ◽  
H.C. de Stigter ◽  
I.N. McCave ◽  
L. Thomsen
Keyword(s):  
Continental Margin ◽  
Sediment Accumulation ◽  
Carbon Burial ◽  
Recent Sediments ◽  
Goban Spur

scholarly journals Organic carbon burial efficiency in a subtropical hydroelectric reservoir

2016 ◽  
Vol 13 (11) ◽  
pp. 3331-3342 ◽  
Author(s):  
Raquel Mendonça ◽  
Sarian Kosten ◽  
Sebastian Sobek ◽  
Simone Jaqueline Cardoso ◽  
Marcos Paulo Figueiredo-Barros ◽  
...  
Keyword(s):  
Organic Carbon ◽  
High Efficiency ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Low Oxygen ◽  
Spatially Resolved ◽  
Natural Lakes ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Burial Efficiency

Abstract. Hydroelectric reservoirs bury significant amounts of organic carbon (OC) in their sediments. Many reservoirs are characterized by high sedimentation rates, low oxygen concentrations in bottom water and a high share of terrestrially derived OC, and all of these factors have been linked to a high efficiency of OC burial. However, investigations of OC burial efficiency (OCBE, i.e., the ratio between buried and deposited OC) in reservoirs are limited to a few studies, none of which include spatially resolved analyses. In this study we determined the spatial variation in OCBE in a large subtropical reservoir and related it to sediment characteristics. Our results show that the sediment accumulation rate explains up to 92 % of the spatial variability in OCBE, outweighing the effect of other variables, such as OC source and oxygen exposure time. OCBE at the pelagic sites varied from 48 to 86 % (mean 67 %) and decreased towards the dam. At the margins, OCBE was lower (9–17 %) due to the low sediment accumulation in shallow areas. Our data show that the variability in OCBE both along the rivers–dam and the margin–pelagic axes must be considered in whole-reservoir assessments. Combining these results with a spatially resolved assessment of sediment accumulation and OC burial in the studied reservoir, we estimated a spatially resolved mean OC burial efficiency of 57 %. Being the first assessment of OCBE with such a high spatial resolution in a reservoir, these results suggest that reservoirs may bury OC more efficiently than natural lakes.

scholarly journals Organic carbon production, mineralization and preservation on the Peruvian margin

2014 ◽  
Vol 11 (9) ◽  
pp. 13067-13126 ◽  
Author(s):  
A. W. Dale ◽  
S. Sommer ◽  
U. Lomnitz ◽  
I. Montes ◽  
T. Treude ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Water Column ◽  
Water Depth ◽  
Dissolved Inorganic Carbon ◽  
Sediment Accumulation ◽  
Inner Shelf ◽  
Global Database ◽  
Carbon Burial ◽  
Organic Carbon Burial

Abstract. Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

scholarly journals Organic carbon production, mineralisation and preservation on the Peruvian margin

2015 ◽  
Vol 12 (5) ◽  
pp. 1537-1559 ◽  
Author(s):  
A. W. Dale ◽  
S. Sommer ◽  
U. Lomnitz ◽  
I. Montes ◽  
T. Treude ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Water Column ◽  
Sediment Accumulation ◽  
Global Database ◽  
Water Oxygen ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Degraded Material ◽  
Rain Rates

Abstract. Carbon cycling in Peruvian margin sediments (11 and 12° S) was examined at 16 stations, from 74 m water depth on the middle shelf down to 1024 m, using a combination of in situ flux measurements, sedimentary geochemistry and modelling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates decreased sharply seaward of the middle shelf and subsequently increased at the deep stations. The organic carbon burial efficiency (CBE) was unusually low on the middle shelf (<20%) when compared to an existing global database, for reasons which may be linked to episodic ventilation of the bottom waters by oceanographic anomalies. Deposition of reworked, degraded material originating from sites higher up on the slope is proposed to explain unusually high sedimentation rates and CBE (>60%) at the deep oxygenated sites. In line with other studies, CBE was elevated under oxygen-deficient waters in the mid-water oxygen minimum zone. Organic carbon rain rates calculated from the benthic fluxes alluded to efficient mineralisation of organic matter in the water column compared to other oxygen-deficient environments. The observations at the Peruvian margin suggest that a lack of oxygen does not greatly affect the degradation of organic matter in the water column but promotes the preservation of organic matter in sediments.

scholarly journals Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarem, Brazil

2017 ◽  
Author(s):  
Luciana M. Sanders ◽  
Kathryn Taffs ◽  
Debra Stokes ◽  
Christian J. Sanders ◽  
Alex Enrich-Prast ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Sediment Accumulation ◽  
Lacustrine Sediments ◽  
Open Water ◽  
Depositional Environments ◽  
Floodplain Lake ◽  
Δ13c And Δ15n ◽  
Amazon Floodplain ◽  
Carbon Burial ◽  
Deforestation Rates

Abstract. The forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. However, potentially important effects of ongoing deforestation in the watershed on these carbon fluxes is still poorly understood. Here, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and land cover/use. Historical records from 1942 and satellite data from 1975 were used to calculate deforestation rates between 1942 and 1975, and 1975 to 2008 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000-m buffers). Sediment accumulation rates were determined from the 240&amp;plus;239Pu signatures and the excess 210Pb method, reaching near 3.8 and 4.2 mm year−1 in the last 60 and 120 years respectively. The average carbon burial rates ranged between 100 and 350 g C m−2 year−1, with pulses of high carbon burial derived from the forest vegetation, as indicated by δ13C and δ15N signatures, which corresponded to heavy deforestation in the 1940 and 50s. Finally, our results revealed a potentially important spatial dependence of the OC burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100-m buffer) during the period 1942–1975 and the larger open water areas (500, 1000 and 6000-m buffer) during 1975–2008. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation around 1950. Our novel findings suggest the importance of abrupt and temporary events in which some of the biomass released by the deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

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