EXPERIMENTAL EFFECTS OF AN ORGANIC MATTER PULSE AND OXYGEN DEPLETION ON A BENTHIC FORAMINIFERAL SHELF COMMUNITY

2005 ◽  
Vol 35 (3) ◽  
pp. 177-197 ◽  
Author(s):  
S. Ernst
Keyword(s):  
Organic Matter ◽  
Oxygen Depletion

scholarly journals Understanding the Biogeochemical Impacts of Fish Farms Using a Benthic-Pelagic Model

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2384
Author(s):  
Evgeniy Yakushev ◽  
Philip Wallhead ◽  
Paul Renaud ◽  
Alisa Ilinskaya ◽  
Elizaveta Protsenko ◽  
...  
Keyword(s):  
Organic Matter ◽  
Transport Model ◽  
Ammonium Phosphate ◽  
Oxygen Depletion ◽  
Fish Farm ◽  
Transformation Model ◽  
Fish Farms ◽  
Spatial And Temporal Scales ◽  
Benthic Biogeochemistry ◽  
Farming Industry

Sustainable development of the salmon farming industry requires knowledge of the biogeochemical impacts of fish farm emissions. To investigate the spatial and temporal scales of farm impacts on the water column and benthic biogeochemistry, we coupled the C-N-P-Si-O-S-Mn-Fe transformation model BROM with a 2-dimensional benthic-pelagic transport model (2DBP), considering vertical and horizontal transport in the water and upper 5 cm of sediments along a 10 km transect centered on a fish farm. The 2DBP model was forced by hydrophysical model data for the Hardangerfjord in western Norway. Model simulations showed reasonable agreement with field data from the Hardangerfjord in August 2016 (correlations between the model and observations were significant for most variables, and model biases were mostly <35%). The model predicted significant impacts on seafloor biogeochemistry up to 1 km from the fish farm (e.g., increased organic matter in sediments, oxygen depletion in bottom water and sediments, denitrification, metal and sulfur reduction), as well as detectable decreases in oxygen and increases in ammonium, phosphate and organic matter in the surface water near to the fish farm.

Modeled based analysis of fish farm emissions impact on the fjord biogeochemistry

2020 ◽  
Author(s):  
Evgeniy Yakushev ◽  
Anfisa Berezina
Keyword(s):  
Organic Matter ◽  
Transport Model ◽  
Model Performance ◽  
Oxygen Depletion ◽  
Horizontal Resolution ◽  
Fish Farm ◽  
Transformation Model ◽  
Model Data ◽  
Sulfur Reduction ◽  
Satisfactory Model

&lt;p&gt;To investigate the impacts of fish farm emissions, we coupled the biogeochemical C-N-P-Si-O-S-Mn-Fe transformation model BROM with a 2-Dimensional Benthic-Pelagic transport model (2DBP), considering vertical and horizontal transport in the water and upper 5 cm&amp;#160; sediments along a 10000 m transect centered on a fish farm. The 2DBP model had 25 m horizontal resolution and was forced by hydrophysical model data for the Hardangerfjord in western Norway. The model predicted significant impacts on seafloor biogeochemistry up to 500 meters from the fish farm (e.g., increased organic matter in sediments, oxygen depletion in water and sediments, denitrification, metal and sulfur reduction) as well as detectable decreases in oxygen and increases in ammonia, phosphate and organic matter in the water near to the fish farm cages. The model results are compared with field data from the Hardangerfjord in August 2016 and indicated satisfactory model performance.&lt;/p&gt;

scholarly journals The Relationship between Mollusks and Oxygen Concentrations in Todos Santos Bay, Baja California, Mexico

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
J. Gabriel Kuk-Dzul ◽  
Victoria Díaz-Castañeda
Keyword(s):  
Organic Matter ◽  
Dissolved Oxygen ◽  
Bottom Water ◽  
Organic Matter Content ◽  
Oxygen Depletion ◽  
Matter Content ◽  
The Other ◽  
Natural Conditions ◽  
The Relationship ◽  
Oxygen Concentrations

This study describes the relationship between mollusks, physicochemical properties of seawater, and sediments under natural conditions of low impact. Thirty-nine stations were sampled in October 1994 using a Van Veen grab (0.1 m−2). Temperature, salinity, and dissolved oxygen (DO) concentrations of bottom water were obtained with a CTD. Organic matter content and sediment grain analysis were determined. A total of 836 mollusks were collected. Gastropoda was the most abundant (52%) and diverse class with 27 genera, followed by Bivalvia with eight genera and Scaphopoda with only one genus. According to CCA analysis, dominant mollusks were significantly related with high DO concentrations.Donax,Natica,Acteocina,Bulla,Anachis,Odostomia, andCrucibulumcan be classified as sensitive genera because they were found mainly in high oxygen concentrations (3.1–5.6 mL L−1); on the other hand,Cardiomya,Nuculana,Laevicardium,Chione,Truncatella, andDentaliumcan be classified as tolerant genera (1.0–5.6 mL L−1). Todos Santos Bay hosts a diverse malacological fauna (36 genera); our results show that the dominant genera were mainly related to high dissolved oxygen concentrations. Mollusks can be a useful tool in environmental monitoring programs related with oxygen depletion in coastal areas.

scholarly journals Deep-water inflow event increases sedimentary phosphorus release on a multi-year scale

2021 ◽  
Vol 18 (9) ◽  
pp. 2981-3004
Author(s):  
Astrid Hylén ◽  
Sebastiaan J. van de Velde ◽  
Mikhail Kononets ◽  
Mingyue Luo ◽  
Elin Almroth-Rosell ◽  
...  
Keyword(s):  
Organic Matter ◽  
Deep Water ◽  
Oxygen Depletion ◽  
Inorganic Phosphorus ◽  
Phosphorus Release ◽  
Water Inflow ◽  
Low Oxygen ◽  
In Situ Experiment ◽  
Inflow Event ◽  
The Baltic

Abstract. Phosphorus fertilisation (eutrophication) is expanding oxygen depletion in coastal systems worldwide. Under low-oxygen bottom water conditions, phosphorus release from the sediment is elevated, which further stimulates primary production. It is commonly assumed that re-oxygenation could break this “vicious cycle” by increasing the sedimentary phosphorus retention. Recently, a deep-water inflow into the Baltic Sea created a natural in situ experiment that allowed us to investigate if temporary re-oxygenation stimulates sedimentary retention of dissolved inorganic phosphorus (DIP). Surprisingly, during this 3-year study, we observed a transient but considerable increase, rather than a decrease, in the sediment efflux of DIP and other dissolved biogenic compounds. This suggested that the oxygenated inflow elevated the organic matter degradation in the sediment, likely due to an increase in organic matter supply to the deeper basins, potentially combined with a transient stimulation of the mineralisation efficiency. As a result, the net sedimentary DIP release per m2 was 56 %–112 % higher over the years following the re-oxygenation than before. In contrast to previous assumptions, our results show that inflows of oxygenated water to anoxic bottom waters can increase the sedimentary phosphorus release.

The Mercury Problem in Recently Formed Reservoirs of Northern Manitoba (Canada): Effects of Impoundment and Other Factors on the Production of Methyl Mercury by Microorganisms in Sediments

1988 ◽  
Vol 45 (1) ◽  
pp. 97-121 ◽  
Author(s):  
Togwell A. Jackson
Keyword(s):  
Organic Matter ◽  
Methyl Mercury ◽  
Inorganic Mercury ◽  
Oxygen Depletion ◽  
Main Stream ◽  
Minor Importance ◽  
River Diversion ◽  
Marked Rise ◽  
Aerobic Conditions ◽  
Mercury Production

Creation of hydroelectric reservoirs by enlargement of riverine lakes and flooding of adjacent forested land along the Churchill River diversion route has led to a marked rise in rates of methyl mercury production by microorganisms in sediments. This phenomenon has resulted primarily from stimulation of microbial activity by organic matter in submerged land areas and is due both to utilization of organic nutrients by methylators and to concomitant oxygen depletion. Release of mercury from scattered low-level sources in this organic matter is a secondary contributing factor. Compared with submerged terrestrial organics, organic matter from aquatic biota has only been of minor importance in promoting methyl mercury production. In some regions, clay and silt eroded from shoreline deposits have inhibited methyl mercury production appreciably. The aerobic conditions prevailing in well-flushed main-stream regions tend to increase the "availability" of sediment-bound inorganic mercury for methylation while decreasing the rate at which microbes are able to methylate the mercury; under less aerobic conditions in quiet backwater regions, the reverse is true.

scholarly journals KAJIAN KETERKAITAN ANTARA CADANGAN OKSIGEN DENGAN BEBAN BAHAN ORGANIK DI ZONA LAKUSTRIN DAN TRANSISI WADUK IR. H. DJUANDA

2017 ◽  
Vol 14 (1) ◽  
pp. 1 ◽  
Author(s):  
Asmika H. Simarmata ◽  
Enan M. Adiwilaga ◽  
Bibiana W. Lay ◽  
Tri Prartono
Keyword(s):  
Organic Matter ◽  
Oxygen Depletion ◽  
Sampling Station ◽  
Total Organic Matter ◽  
Wet Season ◽  
Chemical Laboratory ◽  
Resources Management ◽  
Aquatic Resources Management ◽  
Department Faculty ◽  
To Receive

Kematian massal ikan pada budi daya ikan dalam karamba jaring apung di Waduk Ir. H. Djuanda hampir selalu terjadi setiap tahun. Deplesi oksigen merupakan faktor yang mempengaruhi kondisi tersebut. Oleh karena itu, penelitian ini dilakukan. Tujuan penelitian ini adalah untuk mengkaji atau menentukan kemampuan perairan dalam menerima beban bahan organik. Penelitian dilakukan di Waduk Ir. H. Djuanda dari bulan Juni 2003 sampai dengan Mei 2004, dengan interval pengambilan contoh setiap bulan. Pengambilan contoh dilakukan di wilayah lakustrin yaitu stasiun L1, L2, dan L3 dan wilayah transisi stasiun T1, T2, dan T3. Pengambilan contoh vertikal meliputi permukaan, kedalaman 7, 15, 25, dan 35 m, dan dasar perairan. Metode dalam penelitian ini adalah survei post fakto. Analisis contoh dilakukan di laboratorium produktivitas perairan, Fakultas Perikanan dan Ilmu Kelautan, Institut Pertanian Bogor dan laboratorium kimia Loka Riset Pemacuan Stok Ikan, Jatiluhur. Parameter yang dianalisis adalah oksigen terlarut, bahan organik total, dan K2 (koefisien peluruhan), sedangkan parameter penunjang adalah suhu dan H2S. Hasil penelitian ini menunjukkan bahwa peningkatan bahan organik menyebabkan deplesi oksigen semakin tajam pada musim hujan di wilayah lakustrin. Konsentrasi bahan organik yang aman adalah 7,76 mg per l. Mass mortality of fishes at Ir. H. Djuanda Reservoir occurs almost every year. Oxygen depletion is one factor that affect the condition. There fore, this research should be done. The carrying capacity at Ir. H. Djuanda Reservoir to receive organic loading were determined in this study. The research conducted at Ir. H. Djuanda Reservoir from June 2003 until May 2004. Horizontal sampling station was conducted based on longitudinal gradient i.e. lacustrine zone (L1, L2, and L3), and transition zone (T1, T2, and T3). Vertical sampling points were at surface, at the depth of 7 m, 15, 25, 35, and 45 m, and at the bottom. Sample analysis carried out in physical chemical laboratory of Aquatic Resources Management Department, Faculty of Fisheries and Marine Science, IPB and chemical laboratory Loka Jatiluhur. The methods of this research were post facto survey descriptive. Dissolved oxygen, total organic matter, and BOD were observed during research.temperature and H2S were observed to support the study. The results showed that the increasing of organic matter cause the steep of oxygen depletion in transition of wet season at lacustrine zone. Acceptable concentration of total organic matter was 7.76 mg per l.

scholarly journals Carbon isotopes of dissolved inorganic carbon reflect utilization of different carbon sources by microbial communities in two limestone aquifer assemblages

2016 ◽  
Author(s):  
Martin E. Nowak ◽  
Valérie F. Schwab ◽  
Cassandre S. Lazar ◽  
Thomas Behrendt ◽  
Bernd Kohlhepp ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Carbon Isotopes ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Oxygen Depletion ◽  
C Isotopes ◽  
Abiotic Controls ◽  
Upper Aquifer

Abstract. Isotopes of dissolved inorganic carbon (DIC) are used to indicate both transit times and biogeochemical evolution of groundwaters. These signals can be complicated in carbonate aquifers, as both abiotic (i.e. carbonate equilibria) and biotic factors influence δ13C and 14C of DIC. We applied a novel graphical method for tracking changes in δ13C and 14C of DIC in two distinct aquifer complexes identified in the Hainich Critical Zone Exploratory (CZE), a platform to study how water transport links surface and shallow groundwaters in limestone and marlstone rocks in central Germany. For more quantitative estimates of contributions of different biotic and abiotic carbon sources to the DIC pool, we used the geochemical modelling program NETPATH, which accounts for changes in dissolved ions in addition to C isotopes. Although water residence times in the Hainich CZE aquifers based on hydrogeology are relatively short (years or less), DIC isotopes in the shallow, mostly anoxic, aquifer assemblage (HTU) were depleted in 14C compared to a deeper, oxic, aquifer complex (HTL). Carbon isotopes and chemical changes in the deeper HTL wells could be explained by interaction of recharge waters equilibrated with post-bomb 14C sources with carbonates. However, oxygen depletion and δ13C and 14C values of DIC below those expected from the processes of carbonate equilibrium alone indicate dramatically different biogeochemical evolution of waters in the upper aquifer assemblage (HTU wells). Changes of 14C and 13C in the upper aquifer complexes result from a number of biotic and abiotic processes, including oxidation of 14C depleted OM derived from recycled microbial carbon and sedimentary organic matter as well as water rock interactions. The microbial pathways inferred from DIC isotope shifts and changes in water chemistry in the HTU wells were supported by comparison with in situ microbial community structure based on 16S rRNA analyses. Our findings demonstrate the large variation in the importance of biotic as well as abiotic controls on 13C and 14C of DIC in closely related aquifer assemblages. Further, they support the importance of subsurface derived carbon sources like DIC for chemolithoautotrophic microorganisms as well as rock-derived organic matter for supporting heterotrophic groundwater microbial communities and indicate that even shallow aquifers have microbial communities that use a variety of subsurface derived carbon sources.

Modelling benthic activity in shallow eutrophic rivers

1998 ◽  
Vol 37 (3) ◽  
pp. 129-137 ◽  
Author(s):  
W. Rauch ◽  
P. A. Vanrolleghem
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Bacterial Species ◽  
Oxygen Depletion ◽  
Order Reaction ◽  
Fast Computation ◽  
Mass Balances ◽  
Multiple Substrate ◽  
Modelling Approach

In this paper a simple modelling approach is presented that allows fast computation of benthic activity in rivers. The approach extends the half-order reaction concept used in biofilm models for use in a multiple substrate/multiple bacterial species system. Moreover, it is compatible with the IAWQ Activated Sludge Model no. 1 format and has closed mass balances. The conversion of carbonaceous organic matter under aerobic and anoxic conditions and nitrification are represented in the model. The case study to which it was applied revealed that benthic activity is highly influenced by the eutrophic state of the river (presence/absence of algae) leading to diurnal oxygen fluctuations. More specifically the spatial distribution of species along the river was significantly different, resulting in postponed (downstream) nitrification in the eutrophied river. Also, oxygen depletion is found to be more severe and its spatial extension is larger.

Oxygen Depletion Modelling, Port Shelter, Hong Kong

1986 ◽  
Vol 18 (7-8) ◽  
pp. 277-287
Author(s):  
J. Krogsgaard Jensen ◽  
A. Malmgren-Hansen ◽  
P. Mortensen
Keyword(s):  
Organic Matter ◽  
Hong Kong ◽  
Decay Rate ◽  
Oxygen Concentration ◽  
Dispersion Model ◽  
Vertical Mixing ◽  
Oxygen Demand ◽  
Bottom Layer ◽  
Oxygen Depletion ◽  
Sensitivity Analyses

In order to describe and evaluate the effect on the oxygen concentrations of a planned sewage outlet in the Port Shelter Bay in Hong Kong, a relatively simple BOD-DO-box model has been established. The model describes the oxygen concentration in 6 horizontal boxes in the central part of Port Shelter. Each box is vertically divided into 4 layers (sub-boxes). The oxygen concentration in each layer is described as a function of the vertical and the horizontal mixing, the oxygen demand of the sediment and the concentration of organic matter in the water. A finite difference transport dispersion model provided input data for the BOD-DO model. Two main calculations have been made: one simulating the cold season (15°C) and one simulating the warm season (30°C). Furthermore sensitivity analyses have been carried out. The calculations show an oxygen depletion of approximately 1 and 2 mg O2/l at 15° and 30°C respectively in the bottom layer over an area of approximately two sq. km. The highest oxygen depletion is calculated in the bottom layer. From the calculation it can further be concluded that the decay rate of organic matter in the water and the vertical mixing will influence the oxygen depletion considerably. In periods where either the decay rate is higher than 3 d−1, or the vertical mixing is considerably low an oxygen depletion higher than the calculated can be expected. The lowest measured oxygen concentration in Port Shelter during the period July-August 1982 was 1.7 mg O2/l. Therefore it can be expected that the planned outlet will cause oxygen-free or nearly oxygen-free conditions in the bottom layer in warm periods with low vertical mixing.

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