Amino acid data of catchment and sediment core samples of four Indian lakes

In the present study, we report the results of comprehensive amino acid (AA) analyses of four Indian lakes from different climate regimes. We focus on the investigation of sediment cores retrieved from the lakes but data of modern sediment as well as vascular plant, soil, and suspended particulate matter samples from individual lakes are also presented. Commonly used degradation and organic matter source indices are tested for their applicability to the lake sediments, and we discuss potential reasons for possible limitations. A principal component analysis including the monomeric AA composition of organic matter of all analysed samples indicates that differences in organic matter sources and the environmental properties of the individual lakes are responsible for the major variability in monomeric AA distribution of the different samples. However, the PCA also gives a factor that most probably separates the samples according to their state of organic matter degradation. Using the factor loadings of the individual AA monomers, we calculate a lake sediment degradation index (LI) that might be applicable to other palaeo-lake investigations.

Biomarkers in surface sediments from the Ob and Yenisei estuaries and the southern Kara Sea

Organic-geochemical bulk parameter (Total organic carbon contents, C/N ratios and d13Corg values), biogenic opal and biomarkers (n-alkanes, fatty acids, sterols and amino acids) were determined in surface sediments from the Ob and Yenisei estuaries and the adjacent southern Kara Sea. Maximum TOC contents were determined in both estuaries, reaching up to 3 %. Relatively high C/N ratios around 10, light d13Corg values of -26.5 per mil (Yenisei) and -28 to -28.7 per mil (Ob), and maximum concentrations of long-chain n-alkanes of up to about 10 µg/g Sed clearly show the predominance of terrigenous organic matter in the sediments from the estuaries. Towards the open Kara Sea, all p arameters indicate a decrease in terrigenous organic carbon. Brassicasterol as well as the short-chain n-alkanes parallel this trend, suggesting that these biomarkers are probably also related to a terrigenous (fresh-water phytoplankton) source. Amino acid spectra show characteristic trends from the Yenisei Estuary to the open Kara Sea revealing increasing state of degradation. Sedimentary organic matter in the Yenisei Estuary is relatively less degraded compared to the Ob Estuary and the open Kara Sea.

Amino acids and carbohydrates in sediments and interstitial waters of ODP Site 112-681

Total organic carbon (TOC), dissolved organic carbon (DOC), total hydrolyzable amino acids (THAA), amino sugars (THAS), and carbohydrates (THCHO) were measured in sediments and interstitial waters from Site 681 (ODP Leg 112). TOC concentrations vary between 0.75% and 8.2% by weight of dry sediment and exhibit a general decrease with depth. DOC concentrations range from 6.1 to 49.5 mg/L, but do not correlate with TOC concentrations in the sediment. Amino compounds (AA and AS) and sugars account for 0.5% to 8% and 0.5% to 3% of TOC, respectively, while amino compounds make up between 2% and 27% of total nitrogen. Dissolved hydrolyzable amino acids (free and combined) and amino sugars were found in concentrations from 3.7 to 150 µM and from 0.1 to 3.7 µM, respectively, and together account for an average of 8.5% of DOC. Dissolved hydrolyzable carbohydrates are in the range of 6 to 49 µM. Amino acid spectra are dominated by glycine, alanine, leucine, and phenylalanine; nonproteinaceous amino acids (gamma-amino butyric acid, beta-alanine, and ornithine) are enriched in the deeper part of the section, gamma-amino butyric acid and beta-alanine are thought to be indicators of continued microbial degradation of TOC. Glycine, serine, glutamic acid, alanine, aspartic acid, and ornithine are the dominating amino compounds in the pore waters. Spectra of carbohydrates in sediments are dominated by glucose, galactose, and mannose, while dissolved sugars are dominated by glucose and fructose. In contrast to the lack of correlation between abundances of bulk TOC and DOC in corresponding interstitial waters, amino compounds and sugars do show some correlation between sediments and pore waters: A depth increase of aspartic acid, serine, glycine, and glutamic acid in the pore waters is reflected in a decrease in the sediment, while an enrichment in valine, iso-leucine, leucine, and phenylalanine in the sediment is mirrored by a decrease in the interstitial waters. The distribution of individual hexoseamines appears to be related to zones of bacterial decomposition of organic matter. Low glucoseamine to galactoseamine ratios coincide with zones of sulfate depletion in the interstitial waters.