scholarly journals Bioturbation has a limited effect on phosphorus burial in salt marsh sediments

2020 ◽  
Author(s):  
Sebastiaan J. van de Velde ◽  
Rebecca K. James ◽  
Ine Callebaut ◽  
Silvia Hidalgo-Martinez ◽  
Filip J. R. Meysman
Keyword(s):  
Salt Marsh ◽  
Bottom Water ◽  
Solid Phase ◽  
Organic Phosphorus ◽  
Inorganic Phosphorus ◽  
Sediment Reworking ◽  
Co2 Concentrations ◽  
Bottom Waters ◽  
Salt Marsh Sediments ◽  
The Impact

Abstract. It has been hypothesised that the evolution of animals during the Ediacaran-Cambrian transition had a major impact on atmospheric O2 and CO2 concentrations. The models upon which this hypothesis rests, critically assume that bioturbation by the newly evolved fauna increased the burial of organic phosphorus (Porg) within the seafloor, relative to organic carbon (Corg) and that inorganic phosphorus (Pinorg) burial was not affected by bioturbation. This assumption is centrally based on data compilations from marine sediments deposited under oxic and anoxic bottom waters. Since anoxia excludes the presence of infauna and sediment reworking, the observed differences in P burial are assumed to be solely driven by the presence of bioturbators. This reasoning however ignores the potentially confounding impact of bottom water oxygenation on phosphorus burial. Here, our goal is to provide a field verification for the idea that bioturbation increases the relative burial of organic phosphorus, while accounting for bottom water oxygenation. We present solid-phase phosphorus speciation data from salt marsh ponds with and without bioturbation (Blakeney salt marsh, Norfolk, UK). In both cases, the pond sediments are exposed to oxygenated bottom waters and so the only difference is the presence/absence of bioturbating macrofauna. Our data reveal that both the Corg : Porg ratio of buried organic matter and the rate of Pinorg burial are indistinguishable between bioturbated and non-bioturbated sediments. The absence of a clear effect of bioturbation on total P burial implies that previous studies may have overestimated the impact of the rise of bioturbation on atmospheric O2 and CO2 concentrations in the early Cambrian.

scholarly journals Bioturbation has a limited effect on phosphorus burial in salt marsh sediments

2021 ◽  
Vol 18 (4) ◽  
pp. 1451-1461
Author(s):  
Sebastiaan J. van de Velde ◽  
Rebecca K. James ◽  
Ine Callebaut ◽  
Silvia Hidalgo-Martinez ◽  
Filip J. R. Meysman
Keyword(s):  
Salt Marsh ◽  
Marine Sediments ◽  
Bottom Water ◽  
Solid Phase ◽  
Inorganic Phosphorus ◽  
Limited Effect ◽  
Sediment Reworking ◽  
Bottom Waters ◽  
Salt Marsh Sediments ◽  
Total P

Abstract. It has been hypothesized that the evolution of animals during the Ediacaran–Cambrian transition stimulated the burial of phosphorus in marine sediments. This assumption is centrally based on data compilations from marine sediments deposited under oxic and anoxic bottom waters. Since anoxia excludes the presence of infauna and sediment reworking, the observed differences in P burial are assumed to be driven by the presence of bioturbators. This reasoning however ignores the potentially confounding impact of bottom-water oxygenation on phosphorus burial. Here, our goal is to test the idea that bioturbation increases the burial of organic and inorganic phosphorus (Porg and Pinorg, respectively) while accounting for bottom-water oxygenation. We present solid-phase phosphorus speciation data from salt marsh ponds with and without bioturbation (Blakeney salt marsh, Norfolk, UK). In both cases, the pond sediments are exposed to oxygenated bottom waters, and so the only difference is the presence or absence of bioturbating macrofauna. Our data reveal that the rate of Porg and Pinorg burial are indistinguishable between bioturbated and non-bioturbated sediments. A large terrestrial fraction of organic matter and higher sedimentation velocity than generally found in marine sediments (0.3 ± 0.1 cm yr−1) may partially impact these results. However, the absence of a clear effect of bioturbation on total P burial puts into question the presumed importance of bioturbation for phosphorus burial.

Coupled benthic cycling of iron, phosphorus and sulfur in the Benguela upwelling system

2020 ◽  
Author(s):  
Kristin Anna Ungerhofer ◽  
Gert-Jan Reichart ◽  
Peter Kraal
Keyword(s):  
Water Column ◽  
Bottom Water ◽  
Solid Phase ◽  
Oxygen Depletion ◽  
Biogeochemical Cycles ◽  
Sediment Surface ◽  
Upwelling System ◽  
Benguela Upwelling ◽  
Bottom Waters ◽  
The Impact

<p>The Benguela upwelling system (BUS) offshore Namibia is among the most productive ocean regions worldwide and is a globally important reservoir of biodiversity and biomass. The forcing of cold, nutrient-rich deep waters up the coastal shelf leads to high rates of primary productivity in surface waters, intense carbon remineralization and consequently to (bottom water) oxygen depletion on the shelf that varies temporally and spatially with the intensity of the upwelling.<br>Recurring events of deoxygenation have a severe impact on marine ecosystems, for instance increased mortality and altered biogeochemical cycles of key elements such as carbon (C), iron (Fe), phosphorus (P) and sulfur (S). Therefore, it is crucial that we establish a clear mechanistic framework of the impact of oxygen depletion on (global) biogeochemical cycles, not only to allow for the reconstruction of climate-ocean feedbacks in upwelling regions in the past, but to enable predictions of future behavior.<br>During an expedition with <em>RV Pelagia</em> in February of 2019, we collected water column and sediment samples from the shelf and slope off Namibia (100 to 1517 m water depth, bottom water O<sub>2</sub> between 0.5 and 175 µmol L<sup>-1</sup>) and measured nutrient fluxes in on-board sediment incubations to understand the early diagenetic behavior of those key elements and trace metals underlying the (periodically) oxygen-depleted waters of the BUS.<br>We analyzed dissolved concentrations as well as solid-phase speciation of key elements such as iron (Fe), manganese (Mn), phosphorus (P) and sulfur (S) to understand the chemical and physical processes controlling their distribution along the depth/redox-transect.<br>Our results show intense P cycling on the shelf, as evidenced by very high pore-water P concentrations, an enhanced efflux of PO<sub>4</sub> to suboxic bottom waters and indications of phosphorite formation at depth in the sediment. N/P ratios well below Redfield indicate N depletion and (relative) P accumulation in the water column, a shift in nutrient stoichiometry that can impact the composition of microbial communities in such waters. Meanwhile, the slope sediments are overlain by oxic bottom waters, retain P more efficiently and exhibit N/P ratios close to Redfield stoichiometry.<br>The capacity of the sediment to buffer toxic sulfide and prevent its release to the water column was dependent on the abundance of sulfide oxidizers at the sediment surface. Furthermore, the variable accumulation of sulfide affected Fe speciation and sedimentary P retention.<br>Overall, we show an intimate coupling between sedimentary cycles of essential elements in the Benguela upwelling system, a stark contrast between shelf and slope environments that is further enhanced by local variation of oxygen depletion and a very strong role of microbes in driving the cycles.</p>

scholarly journals Characteristics and Distribution of Organic Phosphorus Fractions in the Surface Sediments of the Inflow Rivers around Hongze Lake, China

2020 ◽  
Vol 17 (2) ◽  
pp. 648 ◽  
Author(s):  
Jie Wan ◽  
Xuyin Yuan ◽  
Lei Han ◽  
Hongmeng Ye ◽  
Xiaofan Yang
Keyword(s):  
Ecological Risk ◽  
Surface Sediments ◽  
Yellow River ◽  
Organic Phosphorus ◽  
River Sediments ◽  
Inorganic Phosphorus ◽  
Risk Effects ◽  
Hongze Lake ◽  
Bioavailable Fraction ◽  
The Impact

In this study, the characteristics and distribution of the organic phosphorus (Po) fractions in the surface sediments of seven inflow rivers around Hongze Lake in China were analyzed with a soil Po fraction method, as used by Ivanoff. The relationships between the Po fractions and physiochemical features of sediments were also discussed. The results showed that, the sediments of the rivers had been moderately pollution with certain ecological risk effects except the Waste Yellow River. The relative contribution order of the Po fractions in the sediments was residual Po > HCl-Po > fulvic acid-Po > humic acid-Po > labile organic phosphorus (LOP). Moderately labile organic phosphorus (MLOP) was the main part of the Po forms in the whole sediments. The risk of phosphorus released from river sediments was the highest in the western region, followed by the southwestern region, and finally the northwestern region. There were significant correlations between Po forms and total phosphorus (TP), inorganic phosphorus (Pi), and Po. Non labile organic phosphorus (NLOP) had the strongest correlation with TP. The distribution of Po forms in each region was different due to the impact of human activities, industrial and agricultural production and the land types; the heaver polluted sediments with higher Po fractions. It is suggested that most of the sediments of the inflow rivers in the regions have certain ecological risk effects and P of them have an important contributions on the eutrophication of Hongze Lake. Po forms can provide a reliable theoretical basis for dealing with the change of water quality and should be paid more attention in the lake eutrophication investigation. There was reciprocal transformation between different Po forms, especially non-bioavailable fraction can change into bio-available ones. The results can provide a basis for the earth cycle of phosphorus and a new perspective of eutrophication control of shallow lakes.

scholarly journals Burrowing fauna mediate alternative stable states in the redox cycling of salt marsh sediments

2020 ◽  
Author(s):  
Sebastiaan van de Velde ◽  
Gilad Antler ◽  
Filip Meysman
Keyword(s):  
Salt Marsh ◽  
Salt Marshes ◽  
Solid Phase ◽  
Alternative Stable States ◽  
Redox Cycling ◽  
Iron Cycling ◽  
Stable States ◽  
Positive Feedbacks ◽  
Sediment Biogeochemistry ◽  
The Impact

<p>The East Anglian salt marsh system (UK) has recently generated intriguing data with respect to sediment biogeochemistry. Neighbouring ponds in these salt marshes show two distinct regimes of redox cycling: the sediments are either iron-rich and bioturbated, or they are sulphide-rich and unbioturbated. No conclusive explanation has yet been given for this remarkable spatial co-occurrence.  Using pore-water analysis and solid-phase speciation, I will demonstrate that differences in solid-phase carbon and iron inputs are likely small between pond types, so these cannot act as the direct driver of the observed redox dichotomy. Instead, the results suggest that the presence of bioturbation is the driving force behind the transition from sulphur-dominated to iron-dominated sediments. The presence of burrowing fauna in marine sediments stimulates the mineralisation of organic matter, increases the iron cycling and limits the build-up of free sulphide. Subsequent early diagenetic modelling confirms that the observed regimes in pond geochemistry are caused by negligible differences in solid-phase inputs, which are amplified by positive feedbacks resulting from the impact of bioturbation on iron and sulphur cycling.</p>

scholarly journals Assessment of the Water Quality of the Western Boundary of Kuching Wetland National Park, Sarawak, Malaysia

1970 ◽  
Vol 5 (1) ◽  
pp. 1-10
Author(s):  
Chen-Lin Soo ◽  
Teck-Yee Ling ◽  
Nyanti Lee
Keyword(s):  
Water Quality ◽  
National Park ◽  
Bottom Water ◽  
Organic Phosphorus ◽  
Monitoring Program ◽  
Inorganic Phosphorus ◽  
Western Boundary ◽  
Shrimp Farm ◽  
International Importance

Kuching Wetland National Park (KWNP) is one of the RAMSAR wetlands in Malaysia, a wetland of international importance. Understanding the water quality of the riverine system that drains the KWNP is crucial for sustainable management of the wetland. Hence, the water quality of Sibu Laut River, which forms the western boundary of the park, is described in this study. Three samplings were carried out during low tide along the western boundary of the wetland. Sub-surface and near-bottom water samples at six selected sampling sites were taken and analysed for physico-chemical parameters. The variations between sub-surface and near-bottom water column of those parameters were detectable and due mainly to the influence of tidal currents. A peak of sub-surface organic phosphorus was observed at station 2 next to the village of Sibu Laut whereas elevated near-bottom organic phosphorus was observed at station 4 near to the shrimp farm. Organic phosphorus represents a significant fraction of the total phosphorus, comprising from 59.76% to 83.64% and 62.50% to 78.67% for sub-surface and near-bottom water, respectively. In contrast, inorganic phosphorus was extremely low at most of the stations. There is a significant correlation between organic phosphorus and chlorophyll a, which indicates association of organic phosphorus and phytoplankton in the study area. The present study showed that Sibu Laut River had minimal pollution impact to the wetland, except the elevated sub-surface organic phosphorus near the Sibu Laut Village and elevated near-bottom organic phosphorus near the shrimp farm. Continuous monitoring program is important for early detection of future threats to the water quality of Sibu Laut River.

scholarly journals Response of <i>Nodularia spumigena</i> to <i>p</i>CO<sub>2</sub> – Part 3: Turnover of phosphorus compounds

2013 ◽  
Vol 10 (3) ◽  
pp. 1483-1499 ◽  
Author(s):  
J. Unger ◽  
S. Endres ◽  
N. Wannicke ◽  
A. Engel ◽  
M. Voss ◽  
...  
Keyword(s):  
Organic Phosphorus ◽  
Extracellular Enzyme ◽  
Co2 Concentration ◽  
Inorganic Phosphorus ◽  
Phosphorus Compounds ◽  
Phosphate Limitation ◽  
High Pco2 ◽  
Nodularia Spumigena ◽  
Co2 Concentrations ◽  
Diazotrophic Cyanobacteria

Abstract. Diazotrophic cyanobacteria form extensive summer blooms in the Baltic Sea driving the surrounding surface waters into phosphate limitation. One of the main bloom-forming species is the heterocystous cyanobacterium Nodularia spumigena. N. spumigena exhibits accelerated uptake of phosphate through the release of the extracellular enzyme alkaline phosphatase whose activity also serves as an indicator of the hydrolysis of dissolved organic phosphorus (DOP). The present study investigated the utilisation of DOP and its compounds (e.g., ATP) by N. spumigena during growth under different CO2 concentrations, in order to estimate potential consequences of ocean acidification on the cell's supply with phosphorus (P). Cell growth, the phosphorus pool, and four DOP compounds (ATP, DNA, RNA, and phospholipids) were determined in three setups with different CO2 concentrations (average 341 μatm, 399 μatm, and 508 μatm) during a 15-day batch experiment. The results showed stimulated growth of N. spumigena and a rapid depletion of dissolved inorganic phosphorus (DIP) in all pCO2 treatments. DOP uptake was enhanced by a factor of 1.32 at 399 μatm and of 2.25 at 508 μatm compared to the lowest CO2 concentration. Among the measured DOP compounds, none was found to accumulate preferentially during the incubation or in response to a specific pCO2 treatment. However, at the beginning 61.9 &amp;pm; 4.3% of total DOP were not characterised but comprised the most utilised fraction. This is demonstrated by the decrement of this fraction to 27.4 &amp;pm; 9.9% of total DOP during the growth phase with a preference at high pCO2. Our results indicate a stimulated growth of diazotrophic cyanobacteria at increasing CO2 concentrations which is accompanied by increasing utilisation of DOP as an alternative P source.

The influence of bottom water intrusion events on the biogeochemistry of a coastal fjord

2020 ◽  
Author(s):  
Subhadeep Rakshit ◽  
Andrew Cogswell ◽  
Sebastian Haas ◽  
Emmanuel Devred ◽  
Richard Davis ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Bottom Water ◽  
Water Exchange ◽  
Transport Model ◽  
Biogeochemical Processes ◽  
Low Oxygen ◽  
Eastern Canada ◽  
Oxygen Conditions ◽  
Bottom Waters ◽  
The Impact

&lt;p&gt;Lack of bottom water exchange in fjord-like estuaries can result in low oxygen conditions and creating sites of redox-sensitive biogeochemical processes, such as denitrification. In many of these systems, occasional intrusions of well-oxygenated bottom water may temporarily alter redox gradients and sediment-water biogeochemistry. Quantifying the magnitude and importance of these changes is a challenge due to the short timescales over which these events can occur. Here we present results from Bedford Basin, a 71 m deep coastal fjord in eastern Canada, where a 20-year, weekly timeseries of bottom water conditions indicates that autumn wind-driven intrusion events are a common, but infrequent, feature of its circulation. To examine the impact of these intrusions on biogeochemistry, we deployed a benthic instrument pod at 60 m depth to record high-resolution measurements of temperature, salinity, nitrate, oxygen, and fluorescence over a 4-month period during the fall of 2018.&amp;#160; During this time we captured two intrusion events, one in mid-Oct and another in mid-Nov. Both intrusion events occurred on a timescale of hours and resulted in sharp changes in temperature, salinity, oxygen, and nitrate.&amp;#160; We used these measurements to constrain a coupled sediment-water column reactive transport model to examine the immediate and annual impacts of these intrusion events on oxygen and nitrogen dynamics in the basin bottom waters and across the sediment-water interface.&lt;/p&gt;

scholarly journals Pollen Geochronology from the Atlantic Coast of the United States during the Last 500 Years

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 362
Author(s):  
Margaret A. Christie ◽  
Christopher E. Bernhardt ◽  
Andrew C. Parnell ◽  
Timothy A. Shaw ◽  
Nicole S. Khan ◽  
...  
Keyword(s):  
United States ◽  
Salt Marsh ◽  
Salt Marshes ◽  
Coastal Wetlands ◽  
Atlantic Coast ◽  
The United States ◽  
Pollen Data ◽  
Sediment Reworking ◽  
Salt Marsh Sediment ◽  
The Impact

Building robust age–depth models to understand climatic and geologic histories from coastal sedimentary archives often requires composite chronologies consisting of multi-proxy age markers. Pollen chronohorizons derived from a known change in vegetation are important for age–depth models, especially those with other sparse or imprecise age markers. However, the accuracy of pollen chronohorizons compared to other age markers and the impact of pollen chronohorizons on the precision of age–depth models, particularly in salt marsh environments, is poorly understood. Here, we combine new and published pollen data from eight coastal wetlands (salt marshes and mangroves) along the Atlantic Coast of the United States (U.S.) from Florida to Connecticut to define the age and uncertainty of 17 pollen chronohorizons. We found that 13 out of 17 pollen chronohorizons were consistent when compared to other age markers (radiocarbon, radionuclide 137Cs and pollution markers). Inconsistencies were likely related to the hyperlocality of pollen chronohorizons, mixing of salt marsh sediment, reworking of pollen from nearby tidal flats, misidentification of pollen signals, and inaccuracies in or misinterpretation of other age markers. Additionally, in a total of 24 models, including one or more pollen chronohorizons, increased precision (up to 41 years) or no change was found in 18 models.

Development of Strategies for Glycopeptide Synthesis: An Overview on the Glycosidic Linkage

2020 ◽  
Vol 24 (21) ◽  
pp. 2475-2497
Author(s):  
Andrea Verónica Rodríguez-Mayor ◽  
German Jesid Peralta-Camacho ◽  
Karen Johanna Cárdenas-Martínez ◽  
Javier Eduardo García-Castañeda
Keyword(s):  
Chemical Synthesis ◽  
Solid Phase ◽  
Building Blocks ◽  
Heterogeneous Environments ◽  
Phase Synthesis ◽  
Low Concentrations ◽  
Biological Sources ◽  
Synthetic Routes ◽  
The Impact ◽  
Potential Use

Glycoproteins and glycopeptides are an interesting focus of research, because of their potential use as therapeutic agents, since they are related to carbohydrate-carbohydrate, carbohydrate-protein, and carbohydrate-lipid interactions, which are commonly involved in biological processes. It has been established that natural glycoconjugates could be an important source of templates for the design and development of molecules with therapeutic applications. However, isolating large quantities of glycoconjugates from biological sources with the required purity is extremely complex, because these molecules are found in heterogeneous environments and in very low concentrations. As an alternative to solving this problem, the chemical synthesis of glycoconjugates has been developed. In this context, several methods for the synthesis of glycopeptides in solution and/or solid-phase have been reported. In most of these methods, glycosylated amino acid derivatives are used as building blocks for both solution and solid-phase synthesis. The synthetic viability of glycoconjugates is a critical parameter for allowing their use as drugs to mitigate the impact of microbial resistance and/or cancer. However, the chemical synthesis of glycoconjugates is a challenge, because these molecules possess multiple reaction sites and have a very specific stereochemistry. Therefore, it is necessary to design and implement synthetic routes, which may involve various protection schemes but can be stereoselective, environmentally friendly, and high-yielding. This review focuses on glycopeptide synthesis by recapitulating the progress made over the last 15 years.

Introduction to geomicrobiology

2018 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Fossil Fuels ◽  
Solid Phase ◽  
Direct Reduction ◽  
Iron Oxidation ◽  
Mineral Dissolution ◽  
Precipitation Process ◽  
Soluble Ions ◽  
Chemolithoautotrophic Bacteria ◽  
The Impact

Geomicrobiology, the marriage of geology and microbiology, is about the impact of microbes on Earth materials in terrestrial systems and sediments. Many geomicrobiological processes occur over long timescales. Even the slow growth and low activity of microbes, however, have big effects when added up over millennia. After reviewing the basics of bacteria–surface interactions, the chapter moves on to discussing biomineralization, which is the microbially mediated formation of solid minerals from soluble ions. The role of microbes can vary from merely providing passive surfaces for mineral formation, to active control of the entire precipitation process. The formation of carbonate-containing minerals by coccolithophorids and other marine organisms is especially important because of the role of these minerals in the carbon cycle. Iron minerals can be formed by chemolithoautotrophic bacteria, which gain a small amount of energy from iron oxidation. Similarly, manganese-rich minerals are formed during manganese oxidation, although how this reaction benefits microbes is unclear. These minerals and others give geologists and geomicrobiologists clues about early life on Earth. In addition to forming minerals, microbes help to dissolve them, a process called weathering. Microbes contribute to weathering and mineral dissolution through several mechanisms: production of protons (acidity) or hydroxides that dissolve minerals; production of ligands that chelate metals in minerals thereby breaking up the solid phase; and direct reduction of mineral-bound metals to more soluble forms. The chapter ends with some comments about the role of microbes in degrading oil and other fossil fuels.

Sign in / Sign up

Export Citation Format

Share Document