Quantifying manganese and nitrogen cycle coupling in manganese‐rich, organic carbon‐starved marine sediments: Examples from the Clarion‐Clipperton fracture zone

Mogollón, José M; Mewes, Konstantin; Kasten, Sabine

doi:10.1002/2016gl069117

Cited by 41 publications

(58 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In these sediments, dissolved O 2 concentrations are high at the top and the bottom of the retrieved sediments and lower in-between. Such pore-water profiles can be explained by downward O 2 diffusion from oxygen-rich seawater as well as upward O 2 diffusion from oxygen-rich water migrating through the basaltic basement Mogollón et al, 2016;Ziebis et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Kühn

Versteegh

Villinger

et al. 2017

Geology

View full text Add to dashboard Cite

On the basis of heat-flow measurements, seismic mapping, and sediment pore-water analysis, we demonstrate widespread and efficient ventilation of the 18-22 Ma oceanic crust of the northeast equatorial Pacific Ocean. Recharge and discharge appear to be associated with basement outcrops, including seamounts and north-south-trending faults, along which sediment cover thins out and volcanic rocks are exposed. Low-temperature hydrothermal circulation through the volcanic crust leads to the reduction of heat flow through overlying sediments, with measured heat-flow values that are well below those expected from conductive cooling curves for lithosphere of this age. Typically, dissolved pore-water oxygen decreases from the sediment surface downward, reaching minimum values at mid-depth and rising again in the lower part of the cores investigated, clearly indicating oxygen-rich seawater circulation through the oceanic crust underneath the sediments. If the residence time of the circulating fluids in the upper crust is short or the fluid flux is large, oxic conditions may be preserved, and oxygen can diffuse upwards into the sediments. This process, leading to widespread oxic conditions in the near-basement sediments, may cause the oxidation of residual reduced material stored in the deeper sediments, resulting in downward fluxes of the reaction products into the basement and from there back into the oceans. Considering the widespread existence of this type of off-axis ventilation, the net effect of the resulting return flow of reaction products on biogeochemical cycles and element fluxes (e.g., carbon and nitrogen) may be very large.

show abstract

Section: Discussionmentioning

confidence: 99%

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Kühn

Versteegh

Villinger

et al. 2017

Geology

View full text Add to dashboard Cite

show abstract

“…Low Mn 2+ together with the rapid decrease in nitrate at 0-2 cm depth at D3 (Fig. 2f, g) also suggested that dissolved reduced manganese might act as a reducing agent for nitrate, as was suggested by Aller et al (1998) in the Panama Basin and Mogollón et al (2016) in the deep-sea sediment of the ClarionClipperton fracture zone in the northeast equatorial Pacific.…”

Section: Partitioning Of C Org Oxidation In Accordance With the Distrmentioning

confidence: 85%

“…Adopting the sediment accumulation rate of 0.07 cm year −1 in the UB determined at a station 50 km from D3 (Cha et al, 2005), the average Mn (DCA) content of 1.1 µmol cm −3 at 10-20 cm depth (Fig. 2g) corresponds to a flux for permanent burial of 0.002 mmol m −2 d −1 or just 0.03 % of the Mn reduction rate (Table 3) -i.e., an Mn atom is recycled 3800 times before it finally gets buried, first by stripping from the particles that settle to the seafloor and subsequently, over and over, by reductive dissolution of the Mn oxides that from by reoxidation in the oxic surface layer (or, potentially, in the nitrate zone; Aller et al, 1998;Mogollón et al, 2016). This is a much more extensive recycling than found in the Mn sediment of Skagerrak (130-260 times; Canfield et al, 1993b).…”

Section: Source Of High Mn Oxide Contentmentioning

confidence: 99%

“…In general, aerobic metabolism dominates the organic matter mineralization in deep-sea sediments that are characterized by low organic matter content (Jahnke et al, 1982;Glud, 2008), especially in organic-carbon-starved deep-sea sediments with low sedimentation rates (Mewes et al, 2014D'Hondt et al, 2015;Mogollón et al, 2016). In contrast, owing to high sulfate concentrations in marine sediment, sulfate reduction might account for up to 50 % of total carbon oxidation in continental margins with high organic matter flux (Jørgensen, 1982;Jørgensen and Kasten, 2006;Bowles et al, 2014).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

View full text Add to dashboard Cite

Abstract. Rates and pathways of benthic organic carbon (C org ) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high C org contents (> 2.5 %, dry wt.) and very high contents of Mn oxides (> 200 µmol cm −3 ) and Fe oxides (up to 100 µmol cm −3 ). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant C org oxidation pathways in the center of the UB, comprising 45 and 20 % of total C org oxidation, respectively. By contrast, sulfate reduction was the dominant C org oxidation pathway, accounting for 50 % of total C org mineralization in sediments of the continental slope. The relative significance of each C org oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for C org oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm −3 , which further implies that Mn reduction can be a dominant C org oxidation process even in sediments with lower MnO 2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to C org oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ∼ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high C org content that indicate the UB as a biogeochemical hotspot for turnover of organic matter and nutrient regeneration.

show abstract

“…The geochemical variability which was discovered in the undisturbed as well as disturbed sites elucidates that the deepsea is a highly complex system that is still poorly understood as has also been recently shown for the CCZ (Mewes et al, 2014Mogollón et al, 2016;Kuhn et al, 2017;Volz et al, in review). With respect to polymetallic nodule mining, it will be necessary to carry out baseline studies on the geochemistry of the potentially impacted sites and reference sites for quite a high number of locations to assess the heterogeneity of both, the natural area and the types of impact.…”

Section: Resultsmentioning

confidence: 99%

Biogeochemical Regeneration of a Nodule Mining Disturbance Site: Trace Metals, DOC and Amino Acids in Deep-Sea Sediments and Pore Waters

et al. 2018

Self Cite

View full text Add to dashboard Cite

Increasing interest in deep-sea mineral resources, such as polymetallic nodules, calls for environmental research about possible impacts of mineral exploitation on the deep-sea ecosystem. So far, little geochemical comparisons of deep-sea sediments before and after mining induced disturbances have been made, and thus long-term environmental effects of deep-sea mining are unknown. Here we present geochemical data from sediment cores from an experimental disturbance area at 4,100 m water depth in the Peru Basin. The site was revisited in 2015, 26 years after a disturbance experiment mimicking nodule mining was carried out and compared to sites outside the experimental zone which served as a pre-disturbance reference. We investigated if signs of the disturbance are still visible in the solid phase and the pore water after 26 years or if pre-disturbance conditions have been re-established. Additionally, a new disturbance was created during the cruise and sampled 5 weeks later to compare short-and longer-term impacts. The particulate fraction and pore water were analyzed for major and trace elements to study element distribution and processes in the surface sediment. Pore water and bottom water samples were also analyzed for oxygen, nitrate, dissolved organic carbon, and dissolved amino acids, to examine organic matter degradation processes. The study area of about 11 km 2 was found to be naturally more heterogeneous than expected, requiring an analysis of spatial variability before the disturbed and undisturbed sites can be compared. The disturbed sites exhibit various disturbance features: some surface sediments were mixed through, others had the top layer removed and some had additional material deposited on top. Pore water constituents have largely regained pre-disturbance gradients after 26 years. The solid phase, however, shows clear differences between disturbed and undisturbed sites in the top 20 cm so that the impact is still visible in the plowed tracks after 26 years. Especially the upper layer, usually rich in manganese-oxide Paul et al.Biogeochemical Regeneration After Mining Disturbance and associated metals, such as Mo, Ni, Co, and Cu, shows substantial differences in metal distribution. Hence, it can be expected that disturbances from polymetallic nodule mining will have manifold and long-lasting impacts on the geochemistry of the underlying sediment.

show abstract

Quantifying manganese and nitrogen cycle coupling in manganese‐rich, organic carbon‐starved marine sediments: Examples from the Clarion‐Clipperton fracture zone

Cited by 41 publications

References 54 publications

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Biogeochemical Regeneration of a Nodule Mining Disturbance Site: Trace Metals, DOC and Amino Acids in Deep-Sea Sediments and Pore Waters

Contact Info

Product

Resources

About