What can we learn from amino acids about oceanic organic matter cycling and degradation?

Amino acids (AA) mainly bound in proteins are major constituents of living biomass and non-living organic material in the oceanic particulate and dissolved organic matter pool. Uptake and cycling by heterotrophic organisms lead to characteristic changes in AA composition so that AA based biogeochemical indicators are often used to elucidate processes of organic matter cycling and degradation. We analyzed particulate AA in a large sample set collected in various oceanic regions covering sinking and suspended particles in the water column, sediment samples as well as dissolved AA from water column and pore water samples. The aim of this study was to test and improve the use of AA derived biogeochemical indicators as proxies for organic matter sources and degradation, and to better understand particle dynamics and interaction between the dissolved and particulate organic matter pools. A principal component analysis (PCA) of all data delineates diverging AA compositions of sinking and suspended particles with increasing water depth. A new sinking particle and sediment degradation indicator (SDI) allows a fine-tuned classification of sinking particles and sediments with respect to the intensity of degradation, which is associated with changes of bulk δ15N ratios. This new indicator furthermore is sensitive to sedimentary redox conditions and can be used to detect past anoxic early diagenesis. A second indicator emerges from the AA spectra of suspended particulate matter (SPM) in the epipelagic and that of the meso- and bathypelagic ocean and is a residence time indicator (RTI). The characteristic changes in AA patterns from shallow to deep SPM are recapitulated in the AA spectra of the dissolved organic matter (DOM) pool, so that deep SPM is more similar to DOM than to any of the other organic matter pools. This implies that there is equilibration between finely dispersed SPM and DOM in the deep sea, which may be driven by microbial activity combined with annealing and fragmentation of gels. As these processes strongly depend on physico-chemical conditions in the deep ocean, changes in quality and degradability of DOM may strongly affect the relatively large pool of suspended and dissolved AA in the ocean that amounts to 15 Pg amino acid carbon (AAC) and 89 ± 29 Pg AAC, respectively.

BIOGEOCHEMICAL INDICATORS, ANOMALIES AND THEIR OIL-GEOLOGICAL SIGNIFICANCE (TUNGUSKA BASIN)

Hydro-biogeochemical studies were carried out in the west of the Siberian platform in the basin of the river Podkamennaya Tunguska, where 1204 groundwater sources and watercourses were studied in terms of biogeochemical indicators. The most informative indicators have been established - bacteria that oxidize propane, butane, pentane, benzene, toluene. According to these parameters and total biogenicity, 42 anomalies with areas of 10-200 km2 were identified. In structural and tectonic terms, 20 biogeochemical anomalies are confined to local positive structures, which can be considered promising for oil and gas exploration.

Specifying the approaches to geoinformation monitoring to assess the development dynamics of mining enterprises as natural-technological systems

Introduction. The article considers problems related to the need in a system of indicators assessing mining technological conditions variation based on mining dynamics monitoring as well as its harmful environmental impact, which is constant over an indefinite period of time. Besides, the introduction of a block of biogeochemical indicators into the general indicative system in order to develop effective methods of environmental rehabilitation is associated with the study of self-healing processes, which will allow managing these processes, thereby accelerating the formation of stable and well-functioning ecosystems. Research aim. Base on the research, the article aims to determine approaches to geoinformation monitoring to assess the dynamics of mining enterprises formation as integrated natural-technological systems in order to choose a strategy for the environmentally safe development of natural deposits and technogenic mineral formations. Methodology. An algorithm for assessing the dynamics of mining enterprises formation as naturaltechnological systems is considered as well as the main directions and tasks of geoinformation monitoring as a tool for controlling technical risks and compensating for environmental risks during the development of solid mineral deposits. Results. The article considers methodological aspects of systematic assessment of natural deposits and man-made formations development projects implementation based on geoinformation monitoring data. Besides, the dynamics of mining enterprises formation as natural-technological systems is proposed to be assessed based on the ideology of modeling transient processes where the object changes its parameters from some initial (initial) to prescribed (final) by the approved design documentation. The transition process at least involves: a transformed natural system, a technological system that changes or affects the natural one, and a socio-economic system being a complex where the organizational, financial and economic activities of the enterprise are implemented in management.

Linking biogeochemistry to hydro-geometrical variability in tidal estuaries: a generic modeling approach

This study applies the Carbon-Generic Estuary Model (C-GEM) modeling platform to simulate the estuarine biogeochemical dynamics – in particular the air–water CO2 exchange – in three idealized tidal estuaries characterized by increasing riverine influence, from a so-called "marine estuary" to a "riverine estuary". An intermediate case called "mixed estuary" is also considered. C-GEM uses a generic biogeochemical reaction network and a unique set of model parameters extracted from a comprehensive literature survey to perform steady-state simulations representing average conditions for temperate estuaries worldwide. Climate and boundary conditions are extracted from published global databases (e.g., World Ocean Atlas, GLORICH) and catchment model outputs (GlobalNEWS2). The whole-system biogeochemical indicators net ecosystem metabolism (NEM), C and N filtering capacities (FCTC and FCTN, respectively) and CO2 gas exchanges (FCO2) are calculated across the three idealized systems and are related to their main hydrodynamic and transport characteristics. A sensitivity analysis, which propagates the parameter uncertainties, is also carried out, followed by projections of changes in the biogeochemical indicators for the year 2050. Results show that the average C filtering capacities for baseline conditions are 40, 30 and 22 % for the marine, mixed and riverine estuary, respectively, while N filtering capacities, calculated in a similar fashion, range from 22 % for the marine estuary to 18 and 15 % for the mixed and the riverine estuaries. Sensitivity analysis performed by varying the rate constants for aerobic degradation, denitrification and nitrification over the range of values reported in the literature significantly widens these ranges for both C and N. Simulations for the year 2050 suggest that all estuaries will remain largely heterotrophic, although a slight improvement of the estuarine trophic status is predicted. In addition, our results suggest that, while the riverine and mixed systems will only marginally be affected by an increase in atmospheric pCO2, the marine estuary is likely to become a significant CO2 sink in its downstream section. In the decades to come, such a change in behavior might strengthen the overall CO2 sink of the estuary–coastal ocean continuum.