Organic carbon and amino acid concentration of Karelian shungite rocks from the lake Onego area, Russia

The study of amino acids in the Precambrian shungite rocks of Karelia showed that their contents vary within 25-89 µg/g depending on proportions between shungite and mineral components. It was established that the amino acids exhibit an excess of L-enantiomers. In the shungite rocks, they form organomineral complexes with silica and aluminosilicates, being built in the globular structure of shungite matter. There are several sources of amino acids in shungites: secondary synthesis, microbial pollution, and original amino acids of organic matter in shungite rocks.

(Table T1) Amino acid ratios and concentrations in interstitial waters of seven ODP Leg 201 sites

Proteins and their amino acid building blocks form a major group of biomolecules in all organisms. In the sedimentary environment, proteins and amino acids have two sources: (1) soft tissues and detritus and (2) biotic skeletal structures, dominantly from calcium carbonate-secreting organisms. The focus of this report is on D/L ratios and concentrations of selected amino acids in interstitial waters collected during ODP Leg 201. The Peru margin sites are generally low in carbonates, whereas the open-ocean sites are more carbonate rich. Seifert et al. (1990, doi:10.2973/odp.proc.sr.112.152.1990) reported amino acid concentrations in interstitial waters from Site 681 (ODP Leg 112) comparable to Leg 201 Site 1229.

Analytical results of 19 amino acid analyses from Unit 3.1 of sediment core CRP-1 (Table 1)

Amino acid-based geochronological analyses were carried out on fossil mollusc shell and foraminifera from Unit 3.1, Cape Roberts Project core CRP-1. Ratios of D-alloIsoleucine to L-Isoleucine (D/L) were measured from 19 fossil samples using cation exchange High Performance Liquid Chromatography (HPLC) methods. Preliminary interpretation of these results suggest that Unit 3.1 contains carbonate fossils having multiple ages. The interpreted ages have a bimodal distribution between ~220 Ka (Quaternary) and ~2.4 Ma (Pliocene). However, these results lack a comprehensive regional and taxonomic context for amino acid studies in Antarctica and therefore should be regarded as preliminary age estimates of fossil shell ages.

Bulk and amino acid parameters of core SO188-342KL from the Northern Bay of Bengal for the last 18 ka

The Northern Bay of Bengal (NBoB) is a globally important region for deep-sea organic matter (OM) deposition due to massive fluvial discharge from the Ganges-Brahmaputra-Meghna (G-B-M) rivers and moderate to high surface productivity. Previous studies have focused on carbon burial in turbiditic sediments of the Bengal Fan. However, little is known about the storage of carbon in pelagic and hemipelagic sediments of the Bay of Bengal over millennial time scales. This study presents a comprehensive history of OM origin and fate as well as a quantification of carbon sediment storage in the Eastern Bengal Slope (EBS) during the last 18 ka. Bulk organic proxies (TOC, TIC, TN, d13CTOC, d15NTN) and content and composition of total hydrolysable amino acids (THAA) in a sediment core (SO188-342KL) from the EBS were analyzed. Three periods of high OM accumulation were identified: the Late Glacial (LG), the Bölling/Alleröd (B/A), and the Early Holocene Climatic Optimum (EHCO). Lower eustatic sea level before 15 ka BP allowed a closer connection between the EBS and the fluvial debouch, favoring high terrestrial OM input to the core site. This connection was progressively lost between 15 and 7 ka BP as sea level rose to its present height and terrestrial OM input decreased considerably. Export and preservation of marine OM was stimulated during periods of summer monsoon intensification (B/A and EHCO) as a consequence of higher surface productivity enhanced by cyclonic-eddy nutrient pumping and fluvial nutrient delivery into the photic zone. Changes in the THAA composition indicate that the marine plankton community structure shifted from calcareous-dominated before 13 ka BP to siliceous-dominated afterwards. They also indicate that the relative proportion of marine versus terrestrial OM deposited at site 342KL was primarily driven by relative sea level and enlarged during the Holocene. The ballasting effect of lithogenic particles during periods of high coastal proximity and/or enhanced fluvial discharge promoted the export and preservation of OM. The high organic carbon accumulation rates in the EBS during the LG (18-17 ka BP) were 5-fold higher than at present and comparable to those of glacial upwelling areas. Despite the differences in sediment and OM transport and storage among the Western and Eastern sectors of the NBoB, this region remains important for global carbon sequestration during sea level low-stands. In addition, the summer monsoon was a key promotor of terrestrial and marine OM export to the deep-ocean, highlighting its relevance as regulator of the global carbon budget.

Organic properties of sediments and amino acids in iterstitial waters of ODP Holes 111-677A and 111-678B

The basement at Ocean Drilling Program (ODP) Sites 677 and 678 originated from the Galapagos spreading center of the Costa Rica Rift and has moved about 200 km over the last 6 m.y. (Fig. 1) (Shipboard Scientific Party, 1987, 1988; Scientific Drilling Party, 1987). Sediments about 300 m thick cover basement so young that basal sediments at Sites 677 and 678 have been reheated up to 60?-70?C at Site 677 and altered to limestone and/or chert (Shipboard Scientific Party, 1988). Sediments from both sites indicate (1) a high sedimentation rate (about 48 m/m.y.) and (2) biogenic silica and carbonate as the main constituents of sediments (Table 1) (Shipboard Scientific Party, 1988). Heatflow observations and measurements of interstitial water chemistry around the sites show that Site 677 is in a lower heatflow zone (166 mW/m**2; 1°12.14'N, 83°44.22'W) whereas Site 678 is located in a zone of higher heat flow (250 mW/m**2; 1°13.01'N, 83°43.39'W) (Langseth et al., 1988; Shipboard Scientific Party, 1988). In the flank hydrothermal systems, circulating solution is moving upward through the sedimentary column in zones of higher heat flow while it is moving downward in zones of lower heat flow (Anderson and Skilbeck, 1981). The chemistry of the interstitial waters is modified by several processes such as (1) diagenetic reactions and (2) advective and (3) diffusive transports of dissolved constituents. Analyses of Ca2+ and Mg2+ in interstitial waters from Sites 677 and 678 show that their profiles are mainly controlled by advective transport (Shipboard Scientific Party, 1988). In contrast, the interstitial-water profiles for NH4+, Si, and PO4[3-] are highly affected by reactions in the sediments. Site 677 offers a good opportunity to investigate amino acids in the interstitial waters because sediments of similar compositions have been deposited at constant rates of sedimentation. There are few previous works on amino acid distributions in interstitial waters (Henrichs and Parrington, 1979; Michaelis et al., 1982; Henrichs et al., 1984; Henrichs and Farrington, 1987; Ishizuka et al., 1988). In this chapter, we report (1) Rock-Eval analysis and (2) the composition of total hydrolyzable and dissolved free amino acids (THAA and DFAA, respectively) in the interstitial waters. Our objectives are to discuss (1) the possible origin of organic materials, (2) the characteristics of THAA and DFAA, and (3) their relationships in interstitial waters.

Molecular dissolved organic matter composition and environmental parameters from a laboratory incubation study

Dissolved organic matter (DOM) in the oceans constitutes a major carbon pool involved in global biogeochemical cycles. More than 96% of the marine DOM resists microbial degradation for thousands of years. The composition of this refractory DOM (RDOM) exhibits a molecular signature which is ubiquitously detected in the deep oceans. Surprisingly efficient microbial transformation of labile into RDOM was shown experimentally, implying that microorganisms produce far more RDOM than needed to sustain the global pool. By assessing the microbial formation and transformation of DOM in unprecedented molecular detail for 3 years, we show that most of the newly formed RDOM is molecularly different from deep sea RDOM. Only <0.4% of the net community production was channeled into RDOM molecularly undistinguishable from deep sea DOM. Our study provides novel experimentally derived molecular evidence and data for global models on the production, turnover and accumulation of marine DOM.