Recycling of Organic Matter in the Sediments of Santa Monica Basin, California Borderland

Sediment pollution: An assessment of anthropogenic and geogenic trace element contributions along the central Algerian coast

“…2, 3). This suggests the precipitation of metal sulfide under anoxic conditions (Komada et al, 2016). In contrast, Mn, As, and Na increased significantly and reached the maximum in recently deposited sediments.…”

“…The relationship between organic matter contents and chemical elements was analyzed by Pearson's correlation (Tab. 2); thus, positive correlations are observed between OM and Zn, Cd, and Ag metals (0.55 < r 2 < 0.66), which suggests that organic matter acted as a sink or source for these metals in sediment (Komada et al, 2016;Martínez-Santos et al, 2015). Finally, Na and As were significantly correlated with each other (p < 0.01; r 2 = 0.79) and with TW (p < 0.01) suggesting mobility of both elements in the sediments.…”

Kinetics of organic carbon mineralization and methane formation in marine sediments (Aarhus Bay, Denmark)

“…This implies that POC mineralization decreases smoothly with age of the sediment regardless of the prevailing redox zonation and terminal oxidation pathway of the microbial food chain (Arnosti, 2004). This idea, which is taken for granted in most diagenetic modeling studies (Berner, 1980;Soetaert et al, 1996;Van Cappellen and Wang, 1996;Dale et al, 2008;Burdige et al, 2016a,b;Komada et al, 2016), has been directly confirmed only recently by measured rates of POC mineralization in and below the SR zone in Bornholm Basin using radiotracer techniques (Beulig et al, 2018a). The close correspondence between the depth-integrated methanogenesis rates and the diffusive fluxes of CH 4 to the SMTZ also supports the idea that organic matter degradation in Aarhus Bay continues according to the same power law above and below the SMTZ (Fig.…”

“…Microbial fractionation during SR, methanogenesis and AOM commonly gives rise to a minimum in d 13 C-TCO 2 in the SMTZ (e.g., Blair and Aller, 1995;Borowski et al, 1997;Ussler and Paull, 2008;Pohlman et al, 2008;Torres and Kastner, 2009;Treude et al, 2014). Because the net sum of methanogenesis and AOM is stoichiometrically indistinguishable from organoclastic SR (Table 2), the d 13 C of TCO 2 in the SMTZ is almost equivalent to the d 13 C of the principal source of TCO 2 , that is, POC (Malinverno and Pohlman, 2014;Komada et al, 2016). We found that a d 13 C of À15‰ for POC gave best results for d 13 C-TCO 2 in and above the SMTZ for all stations collectively.…”

The Nature and Distribution of Labile Organic Carbon in Sediments Beneath a Collapsed Ice Shelf: Climate Change Effects on the Antarctic Continental Shelf

“…In the past, determining the abundance of LOC in the seabed has been difficult due to limited sampling resolution and short (on the order of a few months) LOC residence times (Hammond et al, 1996). No direct measurements of LOC have been developed; only proxies for the "reactive" organic carbon content such as Total Hydrolyzable Amino Acids (THAA; e.g., Grémare et al, 2003;Garcia et al, 2010;Sañé et al, 2013b), biopolymeric organic carbon (e.g., Fabiano et al, 1995;Fabiano and Pusceddu, 1998), porewater diagenetic reactions (Arndt et al, 2013;Komada et al, 2016), or chlorophyll-a (e.g., Stephens et al, 1997;Sañé et al, 2011b). Common problems with these approaches include representation of only a small portion of the total LOC pool (such as in the case of chlorophyll-a or THAA) or the approaches also include older, less reactive organic carbon that has limited nutritional value to the benthos (e.g., biopolymeric organic carbon).…”