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.

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

2021 ◽  
Author(s):  
Astrid Hylén ◽  
Sebastiaan J. van de Velde ◽  
Mikhail Kononets ◽  
Mingyue Luo ◽  
Elin Almroth-Rosell ◽  
...  
Keyword(s):  
Deep Water ◽  
Oxygen Depletion ◽  
Inorganic Phosphorus ◽  
Phosphorus Release ◽  
Water Inflow ◽  
Low Oxygen ◽  
In Situ Experiment ◽  
Inflow Event ◽  
Bottom Waters ◽  
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 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 three-year-long 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. As a result, the net sedimentary DIP release per m2 was 35–70 % 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.

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

2021 ◽  
Author(s):  
Per Hall ◽  
Astrid Hylén ◽  
Sebastiaan van de Velde ◽  
Mikhail Kononets ◽  
Mingyue Luo ◽  
...  
Keyword(s):  
Deep Water ◽  
Phosphorus Release ◽  
Water Inflow ◽  
Inflow Event

scholarly journals Causes of the extensive hypoxia in the Gulf of Riga in 2018

2021 ◽  
Author(s):  
Stella-Theresa Stoicescu ◽  
Jaan Laanemets ◽  
Taavi Liblik ◽  
Māris Skudra ◽  
Oliver Samlas ◽  
...  
Keyword(s):  
Bottom Layer ◽  
Oxygen Depletion ◽  
Phosphorus Release ◽  
Meteorological Conditions ◽  
Mitigation Measures ◽  
Sediment Surface ◽  
Water Volume ◽  
Gulf Of Riga ◽  
Baltic Proper ◽  
The Baltic

Abstract. The Gulf of Riga is a relatively shallow bay connected to the deeper central Baltic Sea (Baltic Proper) via straits with sills. The decrease in the near-bottom oxygen levels from spring to autumn is a common feature in the gulf, but in 2018, hypoxia was exceptional. We analyzed temperature, salinity, oxygen, and nutrient data collected in 2018 and historical data available from environmental databases. Forcing data from the study year were compared with their long-term means and variability. The year 2018 was exceptional due to occasionally dominating north-easterly winds supporting the inflow of saltier waters from the Baltic Proper and meteorological conditions causing fast development of thermal stratification in spring. Existing stratification hindered vertical transport between the near-bottom layer (NBL) and the water layers above it. The estimated oxygen consumption rate at the sediment surface in spring-summer 2018 was about 1.7 mmol O2 m−2 h−1 that exceeded the oxygen input to the NBL due to advection and mixing. We suggest that the observed pronounced oxygen depletion was magnified by the prolonged stratified season and haline stratification in the deep layer that maintained a decreased water volume between the seabed and the pycnocline. The observed increase in phosphate concentrations in the NBL in summer 2018 suggests a significant sediment phosphorus release in hypoxic conditions counteracting the mitigation measures to combat eutrophication. We conclude, if similar meteorological conditions as in 2018 could occur more frequently in the future, such extensive hypoxia would be more common in the Gulf of Riga and other coastal basins with similar morphology and human-induced elevated input of nutrients.

scholarly journals Organic acids promote phosphorus release from Mollisols with different organic matter contents

2020 ◽  
Vol 16 (No. 1) ◽  
pp. 59-66
Author(s):  
Xiaoyan Yang ◽  
Chuandong Zhang ◽  
Haiping Gu ◽  
Xiangwei Chen ◽  
Erhui Guo
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Acids ◽  
Inorganic Phosphorus ◽  
Phosphorus Release ◽  
Chemical Fractionation ◽  
P Availability ◽  
Inorganic P ◽  
Soil P ◽  
Fractionation Method

Organic acids could improve the phosphorus (P) availability through enhancing the release of inorganic phosphorus (P<sub>i</sub>) in the soil. However, the effects of organic acids on the P<sub>i</sub> release are still poorly understood, especially from soils with different organic matter contents. Here, a biochemically produced humic acid and P fertiliser were added to the soil to modify the content of the soil organic matter (SOM) and soil P, respectively. And then the soil samples were incubated at 25 °C for 30 days. The release of P<sub>i</sub> fractions (such as H<sub>2</sub>O-P<sub>i</sub>, NaHCO<sub>3</sub>-P<sub>i</sub>, NaOH-P<sub>i</sub>, HCl-P<sub>i</sub>, and Residual-P) from the soils with different organic matter contents in the presence of citric, oxalic, and malic acids was evaluated using a sequential chemical fractionation method. The results showed that the release of the NaHCO<sub>3</sub>-P<sub>i</sub>, NaOH-P<sub>i</sub>, and HCl-P<sub>i</sub> fractions also showed a decreasing trend with an increasing content of soil organic matter, and more NaOH-P<sub>i</sub> than the other P<sub>i</sub> fractions was generally released in the presence of organic acids. Considering the types of organic acids, oxalic acid and malic acid most effectively and least effectively released P<sub>i</sub>, respectively. The path analysis indicated that the NaOH-P<sub>i</sub> release had the highest direct and indirect effects on the total inorganic P (TP<sub>i</sub>) release. NaOH-P<sub>i</sub> was, therefore, the most effective source of P<sub>i</sub> in the Mollisols.

Origin and Preservation Conditions of Organic Matter in the Mozambique Channel: Evidence for Widespread Oxidation Processes in the Deep-Water Domains

2021 ◽  
pp. 106589
Author(s):  
Martina Torelli ◽  
Anne Battani ◽  
Daniel Pillot ◽  
Eric Kohler ◽  
Joel Lopes De Azevedo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Deep Water ◽  
Oxidation Processes ◽  
Mozambique Channel ◽  
Preservation Conditions

scholarly journals Speciation of organosulfur compounds in carbonaceous chondrites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander Zherebker ◽  
Yury Kostyukevich ◽  
Dmitry S. Volkov ◽  
Ratibor G. Chumakov ◽  
Lukas Friederici ◽  
...  
Keyword(s):  
Organic Matter ◽  
Analytical Techniques ◽  
Ion Cyclotron Resonance ◽  
Organosulfur Compounds ◽  
Low Oxygen ◽  
Fticr Ms ◽  
Insoluble Organic Matter ◽  
Composition And Structure ◽  
Extractable Fraction ◽  
The Individual

AbstractDespite broad application of different analytical techniques for studies on organic matter of chondrite meteorites, information about composition and structure of individual compounds is still very limited due to extreme molecular diversity of extraterrestrial organic matter. Here we present the first application of isotopic exchange assisted Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for analysis of alkali extractable fraction of insoluble organic matter (IOM) of the Murchison and Allende meteorites. This allowed us to determine the individual S-containing ions with different types of sulfur atoms in IOM. Thiols, thiophenes, sulfoxides, sulfonyls and sulfonates were identified in both samples but with different proportions, which contribution corroborated with the hydrothermal and thermal history of the meteorites. The results were supported by XPS and thermogravimetric analysis coupled to FTICR MS. The latter was applied for the first time for analysis of chondritic IOM. To emphasize the peculiar extraterrestrial origin of IOM we have compared it with coal kerogen, which is characterized by the comparable complexity of molecular composition but its aromatic nature and low oxygen content can be ascribed almost exclusively to degradation of biomacromolecules.

scholarly journals Cell-free extracellular enzymatic activity is linked to seasonal temperature changes: a case study in the Baltic Sea

2016 ◽  
Vol 13 (9) ◽  
pp. 2815-2821 ◽  
Author(s):  
Federico Baltar ◽  
Catherine Legrand ◽  
Jarone Pinhassi
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Extracellular Enzymes ◽  
Seasonal Pattern ◽  
Critical Factor ◽  
Hydrolytic Activity ◽  
Seasonal Temperature ◽  
The Baltic Sea ◽  
The Baltic ◽  
Hydrolysis Of

Abstract. Extracellular enzymatic activities (EEAs) are a crucial step in the degradation of organic matter. Dissolved (cell-free) extracellular enzymes in seawater can make up a significant contribution of the bulk EEA. However, the factors controlling the proportion of dissolved EEA in the marine environment remain unknown. Here we studied the seasonal changes in the proportion of dissolved relative to total EEA (of alkaline phosphatase (APase), β-glucosidase (BGase), and leucine aminopeptidase (LAPase)), in the Baltic Sea for 18 months. The proportion of dissolved EEA ranged between 37 and 100, 0 and 100, and 34 and 100 % for APase, BGase, and LAPase, respectively. A consistent seasonal pattern in the proportion of dissolved EEA was found among all the studied enzymes, with values up to 100 % during winter and  <  40 % during summer. A significant negative relation was found between the proportion of dissolved EEA and temperature, indicating that temperature might be a critical factor controlling the proportion of dissolved relative to total EEA in marine environments. Our results suggest a strong decoupling of hydrolysis rates from microbial dynamics in cold waters. This implies that under cold conditions, cell-free enzymes can contribute to substrate availability at large distances from the producing cell, increasing the dissociation between the hydrolysis of organic compounds and the actual microbes producing the enzymes. This might also suggest a potential effect of global warming on the hydrolysis of organic matter via a reduction of the contribution of cell-free enzymes to the bulk hydrolytic activity.

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