Biogenic Matter Research Articles

Trophic Status of Lake Niesłysz (Poland) and Related Factors

In order to ensure the protection of lakes against eutrophication, an ongoing global problem, its causes should be determined on an individual basis. In this study, we investigated Lake Niesłysz in northwestern Poland in terms of (i) the impact of nitrogen and phosphorus on primary production, (ii) the Trophic State Index (TSI), and (iii) the hydromorphological characteristics and watershed features. We determined the thermal conditions, dissolved oxygen, organic matter, and selected forms of nitrogen and phosphorus. TSI was determined using Secchi depth (SD), chlorophyll a, total phosphorus (TP), and total nitrogen (TN). Hypolimnetic anoxia was observed in summer. Surface concentrations of chlorophyll a and organic carbon, total inorganic nitrogen (TIN), and total reactive phosphorus (TRP) were 5 μg L−1, 11.7 mg C L−1, 0.049 mg N L−1, and 0.018 mg P L−1, respectively. The TN:TP ratio was >30, while TIN:TRP was <10. The TSIs for chlorophyll a, SD, and TP ranged from 42 to 59, and for TN it was >145. The total trophic state index (T-TSI) exceeded 72. In conclusion, Lake Niesłysz has an average resistance to degradation and the catchment has little influence on the release and transport of biogenic matter into the lake. The limiting nutrient for primary production was phosphorus, but the influence of nitrogen or covariates of nitrogen cannot be excluded. Based on the oxygen conditions in the hypolimnion, the lake should be classified as eutrophic. Most of the TSIs were in the mesotrophic range, while the TSIs for TN and T-TSI classified the lake as hypertonic. The results show that Lake Niesłysz is currently at a critical stage of progressive degradation, and it is advisable to develop and implement protective measures immediately.

Assessment of the Hydrochemical Characteristics of the Carbon Observational Site ‘Carbon-Sakhalin’ (Aniva Bay, Sea of Okhotsk)

Following a tendency of many economies to shift towards carbon neutrality, there came the necessity for certain regions to be assessed in terms of their greenhouse gas emissions from the ocean. A carbon polygon was created in Sakhalin Oblast in order to evaluate the carbon balance of this marine ecosystem in a sub-arctic region, with the possibility of deploying carbon farms for additional CO2 absorption. To obtain such an assessment, it seems crucial to analyze hydrochemical parameters that reflect the situation of the marine environment in Aniva Bay as a basis of the carbon polygon. The article presents the results of the analysis of hydrochemical parameters in Aniva Bay waters and their spatial and seasonal variability. This research was based on available published sources and measurement databases for the period of 1948–1994. Additionally, the review uses hydrochemical data for Aniva Bay in 2001–2013 weather station data for the period of 2008–2023 and weather station data for 2008–2023. Some tendencies were discovered for spatial and temporal distributions of oxygen, pH, and biogenic matter (inorganic phosphorus, inorganic nitrogen, silicon). In surface layers, the mean oxygen year maximum (9.1 mg/L) is registered with the beginning of photosynthesis, i.e., immediately after the ice melting in April. The highest pH values 8.26 are registered in the euphotic layer in May. The lowest pH values was in August (7.96) in the near-bottom layer. The maximum annual P-PO4 registered on the surface (>18 µg/L) immediately after ice melting, with a minimum (7.17 µg/L) at the end of July. Si-SiO3 concentrations have two maximums: at the end of June and at the beginning of October. N-NO2 concentration on the surface is >2 µg/L in mid-July and on the 50 m depth it is >3.5 µg/L in mid-September. Some spatial patterns of hydrochemical parameters were shown based on the analysis of maps.

Influence of a small submarine canyon on biogenic matter export flux in the lower St. Lawrence Estuary, eastern Canada

Abstract. Submarine canyons enhance shelf–slope sediment exchange and influence hydrodynamic processes, with consequences for biogeochemical cycles. This work documents variations in the vertical export of biogenic matter on the northern shore of the lower St. Lawrence Estuary (LSLE, Quebec, eastern Canada), which is characterized by the presence of an active submarine canyon system. A total of three moorings were deployed from November 2020 to September 2021. One nearshore mooring (PDMc) was deployed in the main axis of the Pointe-des-Monts (PDM) canyon system and was equipped with an acoustic Doppler current profiler (ADCP), and two moorings equipped with sediment traps were deployed in the distal PDM canyon system (PDM-154, PDM-224) and offshore Baie-Comeau (BC-133). The ADCP data revealed the occurrence of a minor sediment remobilization event (December 2020) and a small turbidity current (February 2021) in the canyon. Concurrent elevated fluxes of total particulate matter, particulate organic carbon, particulate nitrogen, and chloropigments showed that these events left a signature in sediment traps PDM-154 and PDM-224 located > 2.6 km further offshore by enhancing lateral dispersion of resuspended sediments. The composition of diatom and dinoflagellate assemblages was similar in the canyon system and offshore BC, but the diatom bloom occurred 2 weeks earlier (in mid-April) at the PDM site. A bloom of the potentially toxic diatom Pseudo-nitzschia seriata was also observed during the second half of September 2021 at the BC site. Annual diatom and dinoflagellate fluxes were almost 2 times lower at the PDM site than at the BC site, possibly due to differences in riverine input and the structure of the water column, as well as increased sediment input and resuspension at the PDM site, leading to limited light availability. This study notably helps identify the relationship between near-bed canyon processes and biogenic matter export in the water column, thereby directly influencing the ecosystem offshore PDM. The study period further covered an anomalously nearly ice-free winter, and thus, in the context of climate change, it provides valuable insight into future trends of biogenic matter export in the LSLE.

Drivers of particle sinking velocities in the Peruvian upwelling system

Abstract. As one of Earth's most productive marine ecosystems, the Peruvian upwelling system transports large amounts of biogenic matter from the surface to the deep ocean. Whilst particle sinking velocity is a key factor controlling the biological pump, thereby affecting carbon sequestration and O2-depletion, it has not yet been measured in this system. During a 50 d mesocosm experiment in the surface waters off the coast of Peru, we assessed particle sinking velocities and their biogeochemical and physical drivers. We further characterized the general properties of exported particles under different phytoplankton communities and nutritional states. Average sinking velocities varied between size classes and ranged from 12.8 ± 0.7 m d−1 (particles 40–100 µm) to 19.4 ± 0.7 m d−1 (particles 100–250 µm) and 34.2 ± 1.5 m d−1 (particles 250–1000 µm) (± 95 % CI). Despite a distinct plankton succession from diatoms to dinoflagellates with concomitant 5-fold drop in opal ballasting, substantial changes in sinking velocity were not observed. This illustrates the complexity of counteracting factors driving the settling behaviour of marine particles. In contrast, we found higher sinking velocities with increasing particle size and roundness and decreasing porosity. Size had by far the strongest influence among these physical particle properties, despite a high amount of unexplained variability. Our study provides a detailed analysis of the drivers of particle sinking velocity in the Peruvian upwelling system, which allows modellers to optimize local particle flux parameterization. This will help to better project oxygen concentrations and carbon sequestration in a region that is subject to substantial climate-driven changes.

Differentiated Estimation of the 137Cs Content on the Biogenic and Lithogenic Suspended Matter in the Black Sea

Sedimentation transport of 137Cs can lead to the significant accumulation of this radionuclide at depths that could not be reached through the vertical water exchange alone; therefore, a comparative assessment of its contents for different types of suspended matter (SM) and regions of the Black Sea is of particular interest. For this purpose, we have collected samples of SM and seawater at deep-water and coastal stations for the subsequent determination of the 137Cs activity in the surface water layer. To calculate the fraction of lithogenic matter, the potassium content in the SM was additionally determined. The range of 137Cs content on SM at different stations differed by more than an order of magnitude: from 7 to 111 Bq/kg for specific activity, and from 0.03 to 0.69% for its content on SM, in % of the total content in the surface water layer. Stations located farther away from the coast were characterized by the lowest percentage of 137Cs in SM, while its content at the coastal stations was more variable. The comparison of the lithogenic and biogenic contribution to SM and data on 137Cs for different stations suggests that the content of this radionuclide on SM is primarily determined by the dynamic variations of the lithogenic matter. Based on the 137Cs migration on SM, the Black Sea is divided into at least two types of regions. One regions are water areas far removed from sources of lithogenic matter where SM is formed mainly due to the hydrobiont activity. The 137Cs content in SM due to the predominance of biogenic matter and an insignificant concentration of lithogenic matter in this case accounts for hundredths of a percent of its total content in the surface water layer. Other regions are coastal and shelf water basins, which, on the one hand, are subjected to the significant coastal and river lithogenic runoff, and on the other, they are characterized by the elevated trophicity and biological productivity. In these water areas, 137Cs content on SM owing to the variability of biotic and abiotic factors is more variable and can fluctuate from values typical for the open sea to an order of magnitude higher.

Internal Tides Responsible for Lithogenic Inputs Along the Iberian Continental Slope

AbstractThis study proposes new insights for the interpretation of GEOVIDE particle measurements. Potential resuspension sites due to internal tides (ITs) have been identified along the western Iberian shelf slope using a tidal regional model. Iberian shelf is mainly a source of lithogenic material whereas Galicia Bank is a source of biogenic matter. The potential pathways for particles from the resuspension sites toward the GEOVIDE stations are identified using IBIRYS reanalysis to infer their transport by the ocean circulation. It appears that each station is influenced by a specific pathway and mixed particles from several resuspension sites. This methodology reveals that the criticality of the bathymetry slope, commonly used to track resuspension sites from internal waves, is not sufficient to investigate ITs. An explicit resolution of ITs using a numerical tidal model is required for an exhaustive identification of the resuspension sites.

Abiotic features of Sukhyi and Grygorivskyi Estuaries' ecosystems as seaport water areas (northwestern part of the Black Sea)

The article studies the location, origin and abiotic features of the ecosystems of Sukhyi and Grygorivskyi Estuaries that were transformed into water areas of Chornomorsk and Yuzhnyi, the major seaports of Ukraine, in the second half of the 20th century. It also presents a comparison of the abiotic conditions of such ecosystems based on the analysis of published data and additional database materials of the Institute of Marine Biology of the National Academy of Sciences of Ukraine.
 The construction of permanent and deep watercourses in the water areas of the estuaries alongside with large-scale dredging works led to their transformation into narrow sea bays with the depths significantly exceeding those in the adjacent sea. The construction of berths included levelling the coastline, changing the bottom profile and increasing the water volumes by more than three times. Now the volumes amount to 45–55 million m3 in Sukhyi Estuary and 60–70 million m3 in Grygorivskyi Estuary. The current abiotic features of the estuaries' ecosystems are determined by the processes occurring in Odesa sea region of the northwestern part of the Black Sea where such estuaries are located. The estuaries' hydrochemical regime depends on the yearly meteorological features, the intensity of water exchange with the sea, the amount of biogenic matter coming from natural (surface runoff, precipitation) and anthropogenic sources and the intra-aquatic processes of new organic matter production and destruction. Dredging activities resulted in emergence of the conditions for halocline and thermocline formation that hamper vertical water exchange. The formation of zones with extreme values of dissolved oxygen was also noted during the research. The maximum values in the surface layers result from photosynthesis development, while the minimum values in the bottom layers are caused by accumulation and destruction of dead organic matter. This information can be used to forecast the consequences arising from similar anthropogenic interference in the functioning of coastal marine ecosystems.

ИЗМЕНЕНИЯ КЛИМАТА И ЦВЕТЕНИЕ АРКТИЧЕСКОГО ОЗЕРА ИМАНДРА

Trends of meteorological parameters potentially implicated in harmful algal blooms regularly occurring since early 2000-ies in a major Arctic freshwater basin the lake Imandra have been analyzed. Compared with the preceding period, increases occurred in mean annual and seasonal air temperatures, sunshine duration, and solar radiation, whereas decreases occurred in spring cloudiness and winter precipitates. These changes resulted in altered light regimens in the lake, which were associated with an increased availability of photosynthetically relevant radiation in springtime. In combination with an increased biogenic matter load, this could lead to drastic changes in the structure of phytoplanktonic communities and in their seasonal successions, as well as in biogenic matter dynamics. Based on these considerations and published data, a conceptual model of the emergence and development of regular harmful algal blooms in the lake Imandra is suggested.

Enhanced silica export in a future ocean triggers global diatom decline

Diatoms account for up to 40% of marine primary production1,2 and require silicic acid to grow and build their opal shell3. On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification4–6. Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under {{p}}_{{{rm{CO}}}_{2}} conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.

Archean Biogeochemical Cognizance from Dharwar Craton, India – A Review

Abstract The Banded iron formations (BIFs) and manganese formations of Chitradurga, Shimoga and Sandur greenstone belts of Dharwar craton, associated with the stromatolitic carbonates, carbonaceous phyllites and shales along with gold mineralization, are best geological entities to evaluate the Archean biogeochemical processes and transformation of a habitable Earth. The geochemical anomalies along with C, O and S isotopic signatures of stromatolitic carbonates, carbonaceous phyllites and sulphidic BIFs reflect on biogenic signatures, fluctuating Archean ocean temperatures from 25-75°C and anoxic to euxinic redox conditions. The U-Pb detrital zircon ages of these stromatolitic carbonates indicate 3.5 to 2.6 Ga whereas the carbonaceous shales indicate 3.2 – 2.2 Ga reflecting the transportation of organic matter to the ocean basin during the growth of stromatolitic carbonates. The gold content of carbonaceous phyllites and sulphidic BIFs indicates hydrothermal source. The O2 produced due to stromatolitic activity has deposited Mn and Fe of the Archean oceans as BIFs and Mn formations. The biogenic matter of the stromatolites along with other siliciclastic material, gold and sulphides derived from the volcanic activity mixed and formed as carbonaceous shales in the ocean basin under euxinic conditions. The comprehensive geological, geochemical including isotopic studies on these rock types collectively indicate the interaction of lithosphere-hydrosphere-atmosphere-biosphere in the Archean oceans which paved the way for the advanced forms of life.

The Two Faces of “Case-1” Water

Morel’s “Optical modeling of the upper ocean in relation to its biogenous matter content (Case I waters)” (J. Geophys. Res. - Oceans, Vol. 93, pp. 107,49-10,768, 1988) laid the groundwork to model the optical properties of natural waters based on the concentration of chlorophyll ([Chl], in mg/m 3 ). As stated in the abstract, it aims “tentatively to interpret the optical behavior of oceanic case-I waters,” where “Chlorophyll-like pigment concentration is used as the index to quantify the algal materials,” because [Chl] is routinely measured in marine/oceanic surveys. Specifically, Morel developed “statistical relationships between this index and the depth of euphotic layer, the spectral values of the attenuation coefficient for downwelling irradiance, or the scattering coefficient,” and further, “a pigment-dependent optical model is developed.” Thus, such a system allows many aspects of oceanographic applications when [Chl] (“this index”) is provided. In part, this system established [Chl] at the core of traditional ocean color remote sensing. To implement this system, however, it is necessary to have a complete understanding of the definition and evolution of this Case-1/Case-2 system, especially the qualitative definition of Case-1/Case-2 vs. the practical separation of Case-1/Case-2 as well as the quantitative modeling of the optical properties of Case-1 waters.

Biogenic and anthropogenic sources of sedimentary organic matter in marine coastal areas: A multi-proxy approach based on bulk and molecular markers

The investigation of organic matter sources is an especially challenging issue for marine coastal areas influenced by both natural and anthropogenic inputs. This study focuses on the provenance of sedimentary organic matter deposited in the Gulf of Gdańsk (southern Baltic) and Oslofjord/Drammensfjord (southern Norway) based on the analysis of multiple specific proxies in recent sediments (0–5 cm layer) sampled at 12 sites in 2014. Bulk markers (total organic carbon/total nitrogen [TOC/TN] and stable organic carbon isotopes [δ13CTOC]) and various molecular geochemical markers of organic matter origin (n-alkanes, branched alkanes, unresolved complex mixture [UCM], polycyclic aromatic hydrocarbons [PAHs], hopanes, steranes, and polar steroids including sterols and stanols) were used to comprehensively assess the origin of sedimentary organic matter in the studied basins. The results of this study indicate that the combined use of TOC/TN and δ13CTOC may lead to ambiguous outcomes, and anthropogenic input may affect the sedimentary TOC/TN ratio. The analysis of molecular proxies allowed the identification of locations most impacted by anthropogenic organic matter derived from petrogenic sources and/or sewage effluents and the classification of the studied sites based on the contribution of marine/terrestrial biogenic matter. This study demonstrates that key issues, such as the forms of sedimentary chemical markers, post-depositional changes, and specific diagenetic products, although neglected by some researchers, must be considered for the reliable assessment of organic matter sources. To the best of our knowledge, this is the first such extensive study on surface sediments from the Gulf of Gdańsk and Oslofjord/Drammensfjord in terms of the use of both bulk and molecular markers to investigate organic matter sources.

Is Oxygenation Related to the Decomposition of Organic Matter in Cryoconite Holes?

Cryoconite is a sediment occurring on glacier surfaces worldwide which reduces ice albedo and concentrates glacier surface meltwater into small reservoirs called cryoconite holes. It consists of mineral and biogenic matter, including active microorganisms. This study presents an experimental insight into the influence of sediment oxygenation on the cryoconite ability to produce and decomposition of organic matter. Samples were collected from five glaciers in the Arctic and the European mainland. Cryoconite from three glaciers was incubated in stagnant and mechanically mixed conditions to imitate inter-hole water–sediment mixing by meltwater occurring on glaciers in Northern Hemisphere, and its effect on oxygen profiles and organic matter content. Moreover, we investigated short-term changes of oxygen conditions in cryoconite from four glaciers in illuminated and dark conditions. An anaerobic zone was present or approaching zero oxygen in all illuminated cryoconite samples, varying in depth depending on the origin of cryoconite: from 1500 µm from Steindalsbreen (Scandinavian Peninsula) and Forni Glacier (The Alps) to 3100 µm from Russell Glacier and Longyearbreen (Arctic) after incubation. Organic matter content varied between glaciers from 6.11% on Longyearbreen to 16.36% on Russell Glacier. The mixed sediment from the Forni Glacier had less organic matter than stagnant, the sediment from Longyearbreen followed this trend, but the difference was not statistically significant, while the sediment from Ebenferner did not differ between groups. Our results have implications for the understanding of biogeochemical processes on glacier surfaces, the adaptation of organisms to changing physical conditions due to abrupt sediment mixing, but also on the estimation of productivity of supraglacial systems.

Problems of epy limiting the processes of epy eutrophication in a slightly saline reservoir

One of the most difficult for solving environmental problems of water bodies around the world is the ever-accelerating processes of eutrophication, which are currently mostly anthropogenic in nature. The aim of the work is to identify the biogenic matter that has the greatest influence on the processes of eutrophication and, consequently, limits this process. To clarify this agent of eutrophication, a model experiment was carried out, consisting of a series of tests with the natural water sampled from the Gulf of Taganrog of the Sea of Azov. When solving the problem of the need for and the degree of removal of the biogens from the wastewater, first, the attention should be paid to the biogen that limits the eutrophication of this water system.

BIOGENIC SILICA SEDIMENTATION ON THE SHELF AND CONTINENTAL SLOPE OF THE BLACK SEA

Investigation of the marine sediments processes, regularities of their accumulation in the inland seas is one of the main tasks of marine geology and sedimentology. Biogenic sedimentation is extremely important in the general sediment deposition cycle in the Black Sea basin. This article provides an overview of the literature and analysis of our own research of the distribution of biogenic siliceous deposits in Holocene bottom sediments on the shelf and continental slope of the Black Sea. The composition and conditions of biosilicates formation, their relationship with coccolithic silts and sapropels in sedimentary strata, sources and forms of siliceous biogenic matter input, the dynamics of transformation of modern bottom sediments, as well as the influence of various environmental factors on the process of sedimentary accumulation of silica in the Black Sea basin in the late quarter are considered. The relevance of the topic is caused by insufficient coverage of a number of issues regarding the sources of mobilization and the nature of material input, the features of the origin and deposition of silicate biogenic matter in the basin, paleogeoecological factors that influenced on sedimentogenesis in the late Quarter. The study of the formation processes of modern bottom sediments in a wide range of facies conditions is of undoubted practical importance for diverse geological, sedimentological and facies research, both fundamental and applied, related to prospecting, exploration and exploitation of minerals, as well as for using the results obtained in the development of marine water area.

Phosphorus in the shallow, urban lake subjected to restoration - case study of Lake Domowe Duże in Szczytno

Abstract The paper presents the results of the research on the restoration of the shallow Lake Domowe Duże in Szczytno (area 0.6 km2, average depth 3.4m). Restoration treatments were carried out in the years 2010-2012 and consisted in the inactivation of phosphorus using polyaluminium chloride. Technical restoration was supported by biomanipulation treatments consisting in stocking the lake with predatory fish. Water quality study were carried out before remediation and annually for a decade (2010-2019) during and after the application of coagulant. It was shown that the efficiency of removing excess phosphorus from water column was high (decrease from 0.23 mgP L-1 to 0.05 mgP L-1). The effects achieved during the coagulant application were maintained for 5 years after the end of the project. Currently, the phosphorus pool is still twice as low as before the treatments, but it is gradually increasing. The main external factor limiting permanent improvement of water quality is the open hydrological system and transport of biogenic matter by surface inflows draining anthropogenically transformed areas. Maintaining permanent improvement of water quality will require continuation of restoration measures.

Water-soluble brown carbon in atmospheric aerosols along the transport pathway of Asian dust: Optical properties, chemical compositions, and potential sources

As an important type of light-absorbing aerosol, brown carbon (BrC) has the potential to affect the atmospheric photochemistry and Earth's energy budget. A comprehensive field campaign was carried out along the transport pathway of Asian dust during the spring of 2016, including a desert site (Erenhot), a rural site (Zhangbei), and an urban site (Jinan), in northern China. Optical properties, bulk chemical compositions, and potential sources of water-soluble brown carbon (WS-BrC) were investigated in atmospheric total suspended particulate (TSP) samples. Samples from Zhangbei had higher mass absorption efficiency at 365 nm (MAE365, 1.32 ± 0.34 m2 g−1) than those from Jinan (1.00 ± 0.23 m2 g−1) and Erenhot (0.84 ± 0.30 m2 g−1). Compere to the non-dust samples, elevated water-soluble organic carbon (WSOC) concentrations and MAE365 values of dust samples from Erenhot are related to the input of high molecular weight organic compounds and biogenic matter from the Gobi Desert, while lower values from Zhangbei and Jinan are attributed to the dilution effect caused by strong northwesterly winds. Based on fluorescence excitation–emission matrix spectra and parallel factor analysis, two humic-like (C1 and C2) and two protein-like (C3 and C4) substances were identified. Together, C1 and C2 accounted for ~64% of total fluorescence intensity at the highly polluted urban Jinan site; C3 represented ~45% at the rural Zhangbei site where local biomass burning affects; and C4 contributed ~24% in the desert region (Erenhot) due to dust-sourced biogenic substances. The relative absorptive forcing of WS-BrC compared to black carbon at 300–400 nm was about 31.3%, 13.9%, and 9.2% during non-dust periods at Erenhot, Zhangbei, and Jinan, respectively, highlighting that WS-BrC may significantly affect the radiative balance of Earth's climate system and should be included in radiative forcing models.

Biogenic matter content in marine sediments in the vicinity of the Antarctic Peninsula: Recent sedimentary conditions under a diverse environment of production, transport, selective preservation and accumulation

Burial fluxes of organic carbon and biogenic silica were determined in 17 continental shelf sediment cores collected from the northern Weddell Sea, the Bransfield Strait, and the southern Drake Passage. Coring sites included open-shelf stations as well as slope and glacial trough environments, with water depths varying from 220 to 760 m. Apparent 210Pb accumulation rates from these cores ranged from 0.04 g m−2y−1 to 0.21 g m−2y−1 (1 to 3 mm y−1), with organic carbon burial rates ranging from 3 to 15 g OC m−2y−1 and biogenic silica accumulation rates ranging from 15 to 126 g SiO2 m−2y−1. OC contents below the surface mixed layer ranged from 0.26 to 1.51 wt. % (avg. 0.64 %). Biogenic silica contents at depth ranged from 2.3 to 11.2 wt. % (avg. 7.5%), with an average bSi/OC ratio (wt. %/wt. %) at depth of 12. Annual OC primary production rates and biogenic silica production rates in the euphotic zone were estimated from satellite chlorophyll-a data in the literature and from a seasonal model for biogenic particle export from surface waters. Based on these biogeochemical data, preservation efficiencies (i.e., mass burial rate/water column production rate) were calculated for organic carbon and biogenic silica. These preservation efficiency values ranged from 2 to 18% (avg. 9%) for OC and 8 to 106% (avg. 54%) for bSi. These relatively high preservation efficiencies resulted from extensive lateral sediment focusing (210Pb Psi (Ψ) values [burial flux/water column production rate] ranging from 2 to 33; avg. of 16), cold bottom water temperatures (2 to −2°C), and relatively high biogenic Si and OC production rates in the euphotic zone. The enhanced preservation efficiency for bSi relative to OC (i.e., 54% vs. 9%) in these Antarctic settings is consistent with the change in the phytoplankton bSi/OC (wt. %/wt. %) value of 2 for this area to the burial bSi/OC value of 12. Excess 210Pb activities in surface sediments varied from 4 to 47 dpm g−1. The surface mixed layer in the seabed varied in thickness from 0 to 4 cm. The penetration of excess 210Pb into these Antarctic Peninsula sediments varied from 6 to 28 cm (avg. 18 cm). The inventory of excess 210Pb in the seabed varied from 13 to 230 dpm cm−2 (avg. 110 dpm cm−2). Although 210Pb was the only radionuclide measured in this study, “apparent” 210Pb sediment accumulation rate (SAR) values from these 17 cores (assuming that deep bioturbation is negligible) are believed to be accurate SAR values because of good agreement between 210Pb and 14C chronologies from nearby cores reported in the literature.

Numerical implementation of biological kinetics multi-species model in the Azov Sea

Paper covers the research of biological kinetics processes based on a multi-species model of plankton and fish interaction of the Azov Sea at low and high size considering the V erhulst and Allee effects, competition for resources, taxis, catching, spatial distribution of biogenic matter and detritus. Discrete analogue of developed model problem of water ecology, included in a software complex, were calculated using schemes of increased order of accuracy considering the partial filling of computational cells. The system of grid equations of large dimension, arising at discretization, has been solved on the basis of a two-layer variational type method – the minimum corrections method having the maximum convergence rate. Effective parallel algorithms were developed for numerical implementation of biological kinetics problem and oriented on multiprocessor computer system and NVIDIA Tesla K80 graphics accelerator with the data storage format modification of. Due to it, the reproduction processes of biogeocenose populations have been analysed in real and accelerated time.

The efficiency increasing problems of water biological resources using at the regional level

The fishing structure and amount of vertebrate and invertebrate biological resources are estimated for small limnoecosystems in the forest-steppe zone of the Western Siberia south-west part. The predominance of fish farming based on the maximum use of the natural abiotic and biotic (feeding) resources of the ecosystems, mainly with annual growth of fishes, is noted. Negative abiotic, anthropogenic and socio-economic factors hindering the efficient use of aquatic biological resources are considered. On the Kurgan region territory dominate the small lakes without flow out which has small area (1.0–1.5 km2 ) and depth (up to 3–4 m) with sloping shores, which overgrowing of Phragmites australis. Most lakes are mesotrophic with average biomass of phytoplankton, zooplankton and zoobenthos, as well as the concentration of biogenic matter, or eutrophic. On the Kurgan region territory are in total 7102 lakes of different genesis and size, which area is more than 0.001 km² according to the decoding results of satellite images performed at the Institute of Lake Science of the Russian Academy of Sciences 2010–2013 years (“Lakes of Russia” Information System). For 2019, in the Kurgan region, 3,857.5 tons of aquatic biological resources were obtained as a result of fishing. 99.3% of the total amount of products is accounted for by lake nature use. Fishing increased by 1.3 times compared to 2018. In 2019, 2087 tons of fish of both indigenous and introduced fish species were caught, which amounted to only 45% of the recommended quotes at the region’s lakes. The main part is accounted for by such aboriginal species as crucian (Carassius gibelio, 895.5 tons per year), and peled (Coregonus peled, 1999.4 tons per year). In addition to fish resources, the region lakes are sources of non-fish aquatic biological resources — invertebrate limnobionts. The main species are Gammarus lacustris (Amphipoda) and Artemia salina parthenogenetica (Branchiopoda).