Phosphorus recycling and retention in Lake of the Woods: Reactive-transport diagenetic modeling across spatial and temporal Scales

2021 ◽  
Author(s):  
Md Samrat Alam ◽  
Arthur Zastepa ◽  
Maria Dittrich
Keyword(s):  
Reactive Transport ◽  
Sediment Cores ◽  
Spatial And Temporal Scales ◽  
P Release ◽  
Binding Forms ◽  
Different Seasons ◽  
Environmental Variations ◽  
Reaction Transport ◽  
Phosphorus Recycling ◽  
Diffusive Fluxes

<p>The dynamics of sediment phosphorus (P) remobilization and recycling in many polymictic systems due to distinct external and internal loading conditions are poorly understood. Here we used a multifaceted approach of quantifying sediment P binding forms and corresponding metal contents in sediment cores down to 30 cm from 8 different locations at Lake of Woods (LOW) in different seasons. We also measured pH, redox potential and dissolved oxygen uptake across the sediment-water interface and the concentration of nutrient and metals in pore water at different depths. Additionally, we applied a reaction-transport diagenetic model to construct the spatial and temporal trend of internal P loading in response to environmental variations. The summer diffusive fluxes of P ranged between 3 and 83 µmol m<sup>-2</sup> d<sup>-1 </sup>whereas the winter fluxes were lower ranged from 0.1 to 0.35 µmol m<sup>-2</sup> d<sup>-1</sup>. P recycling efficiency were 13% to 77%. P bound to redox sensitive iron (Fe)-P binding forms in sediments were the major source of P release in all stations, while P immobilization is controlled by redox-insensitive calcium (Ca)-P phases. The modeling results supported the notion that P release was mostly driven by the diagenetic recycling of redox sensitive and organic bound P.</p>

scholarly journals Behaviour of Metal(loid)s at the Sediment-Water Interface in an Aquaculture Lagoon Environment (Grado Lagoon, Northern Adriatic Sea, Italy)

2021 ◽  
Vol 11 (5) ◽  
pp. 2350
Author(s):  
Elisa Petranich ◽  
Matteo Crosera ◽  
Elena Pavoni ◽  
Jadran Faganeli ◽  
Stefano Covelli
Keyword(s):  
Sediment Cores ◽  
Fish Farm ◽  
Trophic Chain ◽  
Water Interface ◽  
Northern Adriatic Sea ◽  
Overlying Water ◽  
Northern Adriatic ◽  
In Situ Experiments ◽  
Diffusive Fluxes ◽  
Lagoon Environment

The cycling of metal(loid)s at the sediment–water interface (SWI) was evaluated at two selected sites (VN1 and VN3) in an active fish farm in the Grado Lagoon (Northern Adriatic, Italy). In situ experiments using a transparent benthic chamber and the collection of short sediment cores were performed, to investigate the behavior of metal(loid)s in the solid (sediments) and dissolved (porewaters) phases. Total and labile concentration of metal(loid)s were also determined in sediments, to quantify their potential mobility. Comparable total concentrations were found at both sites, excluding As, Mn, Pb and V, which were higher at VN3. Metal(loid) porewater profiles showed a diagenetic sequence and a close dependence with redox (suboxic/anoxic) conditions in the surface sediments. Positive diffusive fluxes along with benthic fluxes, particularly at the more oxic site, VN1, were found for almost all metal(loid)s, indicating their tendency to migrate towards the overlying water column. Despite sediments at two sites exhibiting high total metal(loid) concentrations and moderate effluxes at the SWI, the results suggest that they are hardly remobilized from the sediments. Recycling of metal(loid)s from the SWI would not constitute a threat for the aquatic trophic chain in the fish farm.

Variations in the Isotopic Composition of Dissolved Inorganic Carbon in the Unsaturated Zone of a Semi-Arid Region

Radiocarbon ◽  
2015 ◽  
Vol 57 (3) ◽  
pp. 397-406 ◽  
Author(s):  
I Carmi ◽  
D Yakir ◽  
Y Yechieli ◽  
J Kronfield ◽  
M Stiller
Keyword(s):  
Unsaturated Zone ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sediment Cores ◽  
Tritium Content ◽  
Organic Debris ◽  
Different Seasons ◽  
Semi Arid Region ◽  
Semi Arid

A study of water and carbon isotopes was conducted in a bare plot in the unsaturated zone of the Yatir Forest in the northern Negev of Israel. Sediment cores were collected in three different seasons. Measurements include profiles of mineralogy, moisture and its δ18O and tritium content, dissolved inorganic carbon (DIC) and its δ13C (‰) and Δ14C (‰) content, and δ13C (‰) and Δ14C (‰) in the solid sediment. The profiles of moisture and δ18O in the cores show clearly the effect of evaporation. The tritium profile indicates infiltration of water (0.11 m yr−1). The source of carbon in the DIC is CO2 released by biotic activity through roots of trees and of seasonal plants, which show seasonal variations, and by decay of organic debris. The δ13C (‰) profiles show clearly the chemical transition from dissolved CO2 (δ13C = −22‰) to bicarbonate (δ13C = −14‰). At greater depth (–11.3‰), the δ13C becomes similar to the δ13C in the aquifer below (–12.5‰). The effect of secondary processes is evident in the profile of Δ14C in the DIC. It shows a clear decrease with depth due to exchange with the sediment at a rate of 10‰ yr−1. Precipitation of carbon from the DIC on the sediment is 1.1 mg C Lsed−1 yr−1, negligible compared to the 28 g C in 1 Lsed. In the solid sediment, there is a gradient in Δ14Ccarb at the top meter. The net precipitation of 14C from the DIC on the sediment (0.25 to 1.1‰ yr−1), corrected for decay, cannot be observed in the deeper sediment. The presence of 14C in the top 1 m of the sediment is explained by two possible processes: accumulation of 14C-tagged dust (∼0.05 mm yr−1) and/or long-term cumulative precipitation from the DIC.

scholarly journals Underwater Hyperspectral Imaging (UHI): A Review of Systems and Applications for Proximal Seafloor Ecosystem Studies

2021 ◽  
Vol 13 (17) ◽  
pp. 3451
Author(s):  
Juan C. Montes-Herrera ◽  
Emiliano Cimoli ◽  
Vonda Cummings ◽  
Nicole Hill ◽  
Arko Lucieer ◽  
...  
Keyword(s):  
Hyperspectral Imaging ◽  
Spatial Scales ◽  
Marine Ecosystem ◽  
Sediment Cores ◽  
Time Lapse ◽  
Underwater Imaging ◽  
Ecosystem Monitoring ◽  
Ecosystem Research ◽  
Spatial And Temporal Scales ◽  
Functional Features

Marine ecosystem monitoring requires observations of its attributes at different spatial and temporal scales that traditional sampling methods (e.g., RGB imaging, sediment cores) struggle to efficiently provide. Proximal optical sensing methods can fill this observational gap by providing observations of, and tracking changes in, the functional features of marine ecosystems non-invasively. Underwater hyperspectral imaging (UHI) employed in proximity to the seafloor has shown a further potential to monitor pigmentation in benthic and sympagic phototrophic organisms at small spatial scales (mm–cm) and for the identification of minerals and taxa through their finely resolved spectral signatures. Despite the increasing number of studies applying UHI, a review of its applications, capabilities, and challenges for seafloor ecosystem research is overdue. In this review, we first detail how the limited band availability inherent to standard underwater cameras has led to a data analysis “bottleneck” in seafloor ecosystem research, in part due to the widespread implementation of underwater imaging platforms (e.g., remotely operated vehicles, time-lapse stations, towed cameras) that can acquire large image datasets. We discuss how hyperspectral technology brings unique opportunities to address the known limitations of RGB cameras for surveying marine environments. The review concludes by comparing how different studies harness the capacities of hyperspectral imaging, the types of methods required to validate observations, and the current challenges for accurate and replicable UHI research.

Determination of P Release from Rostherne Mere Sediment Cores

2001 ◽  
Vol 29 (2-3) ◽  
pp. 111-117 ◽  
Author(s):  
Vladimir Krivtsov ◽  
David C. Sigee ◽  
Edward G. Bellinger ◽  
Garry Porteous
Keyword(s):  
Sediment Cores ◽  
P Release ◽  
Rostherne Mere

Reactive Transport Simulations of Groundwater-derived Nutrients in a Sandy Beach in Daya Bay, China

2020 ◽  
Author(s):  
Wenli Hu ◽  
Hailong Li ◽  
Kai Xiao
Keyword(s):  
Discharge Tube ◽  
Reactive Transport ◽  
Meteorological Data ◽  
Element Model ◽  
Variable Density ◽  
Daya Bay ◽  
Computational Accuracy ◽  
Near Shore ◽  
Reaction Transport ◽  
Dimensional Variable

<p>Submarine groundwater discharge (SGD) can be a significant terrestrial input of nutrients to the coastal ocean. The mixing between nearshore groundwater and seawater in coastal aquifers modifies the chemical composition of the water prior to discharge. Agricultural, aquaculture and leaky urban sewers may elevate the land-derived contaminates in the near-shore areas. The nutrient structure of Daya Bay has been strongly changed with the economic and urban development. In this study, the spatial distribution of nutrients (e.g. NO<sub>3</sub><sup>-</sup>, NH<sub>4</sub><sup>+</sup>, PO<sub>4</sub><sup>3-</sup>, SO<sub>4</sub><sup>2-</sup>, S<sup>2-</sup>), groundwater salinity and level were systematically investigated along an intertidal beach transect. Two-dimensional variable density and saturation, and nutrient reactive transport simulations were developed using the finite-element model MARUN. Tidal and meteorological data were also collected from local weather station to correct the model boundary.  Besides, surface air evaporation and precipitation were considered in this model to better match the field observations. The results showed that the distribution pattern of nutrients both of field observation and simulation was similar to that of salinity. For example, the concentration of NO<sub>3</sub><sup>-</sup>-N<sup> </sup>from the landward side towards the seaward side of the beach decreased and then increased, presenting an upper NO<sub>3</sub><sup>-</sup>-N<sup> </sup>plume, lower location NO<sub>3</sub><sup>-</sup>-N<sup> </sup>saltwater wedge and NO<sub>3</sub><sup>-</sup>-N<sup> </sup>discharge tube. It can approximately correspond to the upper salt<sup> </sup>plume, classical salt wedge<sup> </sup>and freshwater discharge tube. In stead of using flow velocity or simple attenuation constant to calculate the nutrient fluxes, this study used complex coupled solute reaction transport to improve the computational accuracy.</p>

A New Continuous Terrestrial Archive of Environmental Change during the Last Interglacial/Glacial Cycle – The Loess-Palaeosol-Sequences of the Schwalbenberg (Middle Rhine Valley, Germany)

2020 ◽  
Author(s):  
Peter Fischer ◽  
Olaf Jöris ◽  
Andreas Vött ◽  
Kathryn Fitzsimmons ◽  
Mathias Vinnepand ◽  
...  
Keyword(s):  
Land Surface ◽  
Ice Core ◽  
Sediment Cores ◽  
Luminescence Dating ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Data Set ◽  
Spatial And Temporal Scales ◽  
Rhine Valley ◽  
Ice Core Records

<p>Over the last interglacial/glacial cycle climate variability and forcing in the northern hemisphere is best documented in high resolution from marine and ice core records. The response of land surface processes to climate over this period, however, remains poorly defined. Understanding landscape response to climate change is nevertheless of critical importance not only because as humans we live on and interact with the land, but also in order to identify potential feedbacks and forcings between land and atmosphere which cannot be ascertained from marine and ice core records. In this context, Loess-Palaeosol-Sequences (LPS) are outstanding terrestrial archives allowing detailed reconstruction of palaeoclimate and palaeo­environ­mental changes. However, regarding their complexity, LPS represent polygenetic and multiphase archives over different spatial and temporal scales. Consequently, a solid understanding of geomorphological and pedogenic processes involved in LPS formation, and the interplay with changes in ecological conditions, must be considered before LPS can be correlated with other archives.</p><p>Against this background, extensive fieldwork has been carried out at the Schwalbenberg site near Remagen (Middle Rhine valley, Germany) combining geophysical exploration with Direct Push borehole geophysical measurements and sediment coring. We will present a first comprehensive data set for the Schwalbenberg key area based on a transect from up- to downslope. The integration of grain size, organic carbon and weathering indices from long sediment cores (up to 30 m) and profile sections contribute to a better understanding of processes involved in the Schwalbenberg LPS formation. These data combined with age constraints based on radiocarbon and luminescence dating lead to a first robust chronostratigraphic model of the Last Interglacial/Glacial Cycle suggesting the Schwalbenberg LPS to be a terrestrial archive of palaeoclimate variations in phase with northern hemispheric ice and marine records.</p>

Seasonality in phosphorus release rates from the sediments of a hypereutrophic lake under a matrix of pH and redox conditions

2000 ◽  
Vol 57 (5) ◽  
pp. 1033-1041 ◽  
Author(s):  
Michael R Penn ◽  
Martin T Auer ◽  
Susan M Doerr ◽  
Charles T Driscoll ◽  
Carol M Brooks ◽  
...  
Keyword(s):  
Average Rate ◽  
Sediment Cores ◽  
Redox Status ◽  
Phosphorus Release ◽  
Water Interface ◽  
Concentration Gradients ◽  
Release Rates ◽  
Release Process ◽  
P Release

Phosphorus release rates were measured on intact sediment cores collected from the major depositional basin of Onondaga Lake, a dimictic, calcareous, hypereutrophic system in Syracuse, N.Y., U.S.A. Release experiments were conducted under a matrix of redox and pH conditions to investigate the importance of Ca- and Fe-related physicochemistry on sediment cores collected seasonally, i.e., during the spring, summer, fall, and winter periods. Strong seasonal variation in P release was observed, with rates ranging from ~3 to 38 mg P·m-2·day-1. This variation is attributed to changes in redox status and P concentration gradients at the sediment-water interface. An oxidized microlayer at the sediment-water interface partially inhibits sediment P release under isothermal, well-mixed conditions in the spring and fall. Phosphorus trapped in the oxic microlayer (sorption) is freed when the microlayer is chemically reduced at the onset of anoxia and high P release rates are observed. The oxidized microlayer serves to regulate seasonality in rates of sediment P release but does not influence long-term sediment-water exchange. It is proposed that the long-term P release process is best represented by a time-weighted annual average rate, calculated here to be ~10 mg P·m-2·day-1.

Molecular diffusive fluxes of oxygen in sediments of Port Phillip Bay in south-eastern Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 557 ◽  
Author(s):  
Christopher M. Burke
Keyword(s):  
Sediment Cores ◽  
Sediment Surface ◽  
Overlying Water ◽  
South Eastern ◽  
Eastern Australia ◽  
Oxygen Cycling ◽  
Diffusive Fluxes ◽  
High Degree ◽  
South Eastern Australia

Port Phillip Bay is a large, shallow, semi-enclosed bay in south-eastern Australia. Micro- electrodes were used to measure profiles of oxygen concentration in sediment cores taken from nine sites in the bay in January and February 1994. The effects of sediment surface topography, flow rate of the overlying water and irradiance on the distribution of oxygen in the sediments, and on the molecular diffusive fluxes of oxygen, were determined. Oxygen typically penetrated ≤3 mm into the sediment. Deeper penetration occurred when oxygen was photosynthetically produced in situ. In most cores the sediments consumed oxygen. Molecular diffusive fluxes of oxygen, determined from the gradient of oxygen in the DBL, were compared with fluxes modelled from the sediment gradient of oxygen. The modelled diffusive fluxes are considered to give better estimates of the diffusive fluxes in situ. Modelled fluxes ranged from 1.5 to 28.5 mmol O2 m–2 day–1, which was 43% (s.d. = 36%, n = 16) of the total flux at each site. Cores from two sites demonstrated efflux of oxygen, up to 71 mmol O2 m–2 day–1, as a result of photosynthesis in situ. The high degree of variability in oxygen fluxes within cores demonstrates the dynamism of oxygen cycling in these sediments.

Phosphorus-binding forms in the sediment of an oligotrophic and an eutrophic hardwater lake of the Baltic Lake District (Germany)

1998 ◽  
Vol 37 (3) ◽  
pp. 51-58 ◽  
Author(s):  
Thomas Gonsiorczyk ◽  
Peter Casper ◽  
Rainer Koschel
Keyword(s):  
Eutrophic Lake ◽  
Oligotrophic Lake ◽  
Sediment Surface ◽  
Eutrophic Lakes ◽  
P Release ◽  
Binding Forms ◽  
Fe And Mn ◽  
Lake Stechlin ◽  
High Concentrations ◽  
The Baltic

The vertical distribution of various phosphorus (P)-binding forms, associated potential P-binding partners and the composition of dry material were investigated in the bottom sediments of the dimictic oligotrophic Lake Stechlin and the dimictic eutrophic Lake Feldberger Haussee. Reductant soluble P (Fe- and Mn-bound) at the sediment surface (0−1 cm) was considerably higher in the oligotrophic Lake Stechlin (1.29 g kg−1) than in the eutrophic Lake Haussee (0.32 g kg−1). The amounts of dissolved, loosely adsorbed, metal oxide- and calcium carbonate bound P were higher in the eutrophic lake. The depth profiles of the investigated P species indicated that the mobilization of Fe- and Mn-bound P is the most important mechanism of P-release in oligotrophic lakes, whereas the mobilization of recently sedimented labile organic bound P seems to be the driving force of P-release in eutrophic lakes. In both lakes autochthonous calcite precipitations occurs during the summer months. The coprecipitation of P with calcite is an important self-cleaning mechanism in eutrophic hardwater lakes and contributes to the permanent burial of P in the sediments. Although, the precipitation of calcite is inhibited by the presence of high concentrations of soluble reactive P, the coprecipitation of P with calcite seems to be enhanced.

Sign in / Sign up

Export Citation Format

Share Document