The Effect of Charophyte Communities on Phosphorus Flow in Lake Shinji, Japan

Charophytes are a group of aquatic algae similar to vascular plants; they play an important role in the nutrient cycling of lakes. Specifically, under eutrophication, charophytes have a greater capacity for phosphorus accumulation than vascular plants. During their development, charophytes accumulate calcium within their structures, along with dissolved phosphorus from the water column. The calcified structures are deposited onto the lakebed after the death of the plant, with phosphorus co-precipitating with calcium, limiting its return to the water. Lake Shinji is one of many lakes in Japan where the charophyte population is in decline or extinct. Using aerial photographs acquired 70 years ago, we estimate the extent of the historical charophyte community in Lake Shinji, and quantitatively evaluate and examine the extent to which charophytes accumulated phosphorus in the lake sediment. The amount of phosphorus accumulated by the charophyte community in Lake Shinji is estimated to be 0.56-25.5 t P y-1. Charophytes are not found in Lake Shinji today, and although various species of vascular plants have recolonised the lake, no significant improvement in water transparency has been observed. This study concludes that charophytes are likely to be a more effective measure in combating eutrophication than vascular plants.

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Phosphorus dynamics in the water of tropical semiarid reservoirs in a prolonged drought period

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x1617 ◽

2018 ◽

Vol 30 (0) ◽

Cited By ~ 1

Author(s):

Herika Cavalcante ◽

Fabiana Araújo ◽

Vanessa Becker

Keyword(s):

Water Column ◽

Organic Phosphorus ◽

Soluble Reactive Phosphorus ◽

Particulate Phosphorus ◽

Semiarid Region ◽

Drought Period ◽

Chl A ◽

Dissolved Phosphorus ◽

Phosphorus Dynamics ◽

Prolonged Drought

Abstract Aim To verify the vertical distribution of phosphorus in the water and to identify the predominant forms of P in the water column for understand the phosphorus dynamics in tropical semiarid reservoirs during a prolonged drought period. Methods Two reservoirs from the semiarid region of Rio Grande do Norte were analysed during the period from May 2015 to June 2016. Were analysed: Suspended solids (SS), chlorophyll a (Chl-a), dissolved oxygen (OD) and temperature. Vertical profiles were plotted for total phosphorus (PT), total dissolved phosphorus (PTD), particulate phosphorus (PP), dissolved organic phosphorus (POD) and soluble reactive phosphorus (FRS). Results The phosphorus values distributed in the water column were high for both reservoirs, presenting the highest values during the periods with lower depth. Gargalheiras presented greater predominance of PT and PP, while Cruzeta had the highest values of FRS. Chl-a and SS values were also consistent with phosphorus values: Chl-a was higher in Gargalheiras, while SS, mainly inorganic, were higher in Cruzeta. Gargalheiras presented anoxic conditions close to the sediment from May 2015 to December 2015, which may induce the release of phosphorus from the sediment to the water column. Values that are too high during the shallower months, especially in Cruzeta, may have been influenced by the release of P from sediment through wind resuspension. Conclusions The amounts and predominant types of phosphorus in the water column are of great importance to understand the phosphorus dynamics and will support restoration plans for the studied environments. In this study it was possible to verify that the reservoirs are susceptible to the release of P from the sediment due to the environmental conditions, mainly low depths, resuspension of the wind and anoxia in the hypolimnion.

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Effects of temperature and organic pollution on nutrient cycling in marine sediments

Biogeosciences ◽

10.5194/bg-12-4565-2015 ◽

2015 ◽

Vol 12 (15) ◽

pp. 4565-4575 ◽

Cited By ~ 9

Author(s):

C. Sanz-Lázaro ◽

T. Valdemarsen ◽

M. Holmer

Keyword(s):

Climate Change ◽

Organic Matter ◽

Nutrient Cycling ◽

Water Column ◽

Temperature Rise ◽

Nutrient Release ◽

Organic Pollution ◽

Coastal Sediments ◽

Effect Of Temperature ◽

Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems. In these systems sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, increased linearly with temperature and were significantly higher under organic pollution than under nonpolluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and it was significantly higher in organic polluted compared to nonpolluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible for this behavior. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at a temperature rise > 6 °C could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

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Development of a Submerged Aquatic Vegetation Growth Model in a Coupled Wave-Current-Sediment-Transport Modeling System (COAWST v3.4)

10.5194/gmd-2018-271 ◽

2019 ◽

Author(s):

Tarandeep S. Kalra ◽

Neil K. Ganju ◽

Jeremy M. Testa

Keyword(s):

Sediment Transport ◽

Nutrient Cycling ◽

Water Column ◽

Submerged Aquatic Vegetation ◽

Aquatic Vegetation ◽

Dissolved Inorganic Carbon ◽

Sediment Dynamics ◽

Velocity Sedimentation ◽

Ecosystem Change ◽

Deterministic Modelling

Abstract. The coupled biophysical interactions between submerged aquatic vegetation (SAV), hydrodynamics (currents and waves), sediment dynamics, and nutrient cycling have long been of interest in estuarine environments. Recent observational studies have addressed feedbacks between SAV meadows, current velocity, sedimentation, and nutrient cycling and suggest SAV are ecosystem engineers whose growth can be self-reinforcing. To represent these dynamic processes in a numerical model, the presence of SAV and its effect on hydrodynamics (currents and waves) and sediment dynamics was incorporated into the open source model COAWST. In this study, we extend the COAWST modelling framework to account for dynamic changes of SAV and associated epiphyte biomass. Modelled SAV biomass is represented as a function of temperature, light, and nutrient availability and exchanges nutrients, detritus, dissolved inorganic carbon, and dissolved oxygen with the water-column biogeochemistry model. The dynamic simulation of SAV biomass allows the plants to both respond to and cause changes in water column and sediment bed properties, hydrodynamics, and sediment transport (i.e., a two-way feedback). We demonstrate the behavior of these modelled processes through application to an idealized domain, then apply the model to a eutrophic harbour where SAV dieback is a result of anthropogenic nitrate loading and eutrophication. These cases demonstrate an advance in the deterministic modelling of coupled bio-physical processes and will further our understanding of future ecosystem change.

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Interactions of physical, chemical and biological processes affecting the seasonality of mineral composition and nutrient cycling in the water column of a deep subalpine lake (Lake Garda, Northern Italy)

Fundamental and Applied Limnology / Archiv für Hydrobiologie ◽

10.1127/archiv-hydrobiol/142/1998/385 ◽

1998 ◽

Vol 142 (4) ◽

pp. 385-414 ◽

Cited By ~ 7

Author(s):

Nico Salmaso ◽

Fabio Decet

Keyword(s):

Nutrient Cycling ◽

Water Column ◽

Mineral Composition ◽

Northern Italy ◽

Biological Processes ◽

Lake Garda ◽

Physical Chemical ◽

Subalpine Lake

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Effects of global climate change and organic pollution on nutrient cycling in marine sediments

Biogeosciences Discussions ◽

10.5194/bgd-12-21-2015 ◽

2015 ◽

Vol 12 (1) ◽

pp. 21-49

Author(s):

C. Sanz-Lázaro ◽

T. Valdemarsen ◽

M. Holmer

Keyword(s):

Climate Change ◽

Organic Matter ◽

Nutrient Cycling ◽

Water Column ◽

Temperature Rise ◽

Nutrient Release ◽

Organic Pollution ◽

Coastal Sediments ◽

Effect Of Temperature ◽

Climate Change Scenarios

Abstract. Increasing ocean temperature due to climate change is an important anthropogenic driver of ecological change in coastal systems, where sediments play a major role in nutrient cycling. Our ability to predict ecological consequences of climate change is enhanced by simulating real scenarios especially when the interactions among drivers may not be just additive. Based on predicted climate change scenarios, we tested the effect of temperature and organic pollution on nutrient release from coastal sediments to the water column in a mesocosm experiment. PO43− release rates from sediments followed the same trends as organic matter mineralization rates, and increased linearly with temperature and were significantly higher under organic pollution than under non-polluted conditions. NH4+ release only increased significantly when the temperature rise was above 6 °C, and was significantly higher in organic polluted compared to non-polluted sediments. Nutrient release to the water column was only a fraction from the mineralized organic matter, suggesting PO43− retention and NH4+ oxidation in the sediment. Bioturbation and bioirrigation appeared to be key processes responsible of this behaviour. Considering that the primary production of most marine basins is N-limited, the excess release of NH4+ at temperature rise >6 ° could enhance water column primary productivity, which may lead to the deterioration of the environmental quality. Climate change effects are expected to be accelerated in areas affected by organic pollution.

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Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary

Biogeosciences Discussions ◽

10.5194/bgd-7-2767-2010 ◽

2010 ◽

Vol 7 (2) ◽

pp. 2767-2798 ◽

Cited By ~ 1

Author(s):

D. R. Corbett

Keyword(s):

Water Quality ◽

Nutrient Cycling ◽

Water Column ◽

Bottom Water ◽

River Estuary ◽

Neuse River Estuary ◽

Nutrient Concentrations ◽

Neuse River ◽

Advective Flux ◽

The Past

Abstract. For at least the past several decades, North Carolina's Neuse River Estuary (NRE) has been subject to water quality problems relating to increased eutrophication. Research studies initiated in the past several years have addressed the complex nutrient cycles in this system. Most of this research, however, is concerned with the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, tides, or wind-generated waves, may have a significant effect on the flux of nutrients in an estuarine system These processes can result in the advective transport of sediment porewater, rich with nitrogen, phosphorus and carbon, into the water column. Thus, estimates of nutrient and carbon inputs from the sediments may be too low. This study focused on the potential change in porewater and bottom water nutrient concentrations associated with measured resuspension events. Previous research used short-lived radionuclides and meteorological data to characterize the sediment dynamics of the benthic system of the estuary. These techniques in conjunction with the presented porewater inventories allowed evaluation of the depth to which sediments have been disturbed and the advective flux of nutrients to the water column. The largest removal episode occurred in the lower NRE as the result of a wind event and was estimated that the top 2.2 cm of sediment and corresponding porewater were removed. NH4+ advective flux (resuspended) was 2 to 6 times greater than simply diffusion. Phosphate fluxes were estimated to be 15 times greater than the benthic diffusive flux. Bottom water conditions with elevated NH4+ and PO43− indicate that nutrients stored in the sediments continue to play an important role in overall water quality and this study suggests that the advective flux of nutrients to the water column is critical to understand estuarine nutrient cycling.

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Development of a submerged aquatic vegetation growth model in the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST v3.4) model

Geoscientific Model Development ◽

10.5194/gmd-13-5211-2020 ◽

2020 ◽

Vol 13 (11) ◽

pp. 5211-5228

Author(s):

Tarandeep S. Kalra ◽

Neil K. Ganju ◽

Jeremy M. Testa

Keyword(s):

Sediment Transport ◽

Nutrient Cycling ◽

Water Column ◽

Submerged Aquatic Vegetation ◽

Aquatic Vegetation ◽

Sediment Dynamics ◽

Velocity Sedimentation ◽

Ecosystem Change ◽

Modeling Framework ◽

Ocean Atmosphere

Abstract. The coupled biophysical interactions between submerged aquatic vegetation (SAV), hydrodynamics (currents and waves), sediment dynamics, and nutrient cycling have long been of interest in estuarine environments. Recent observational studies have addressed feedbacks between SAV meadows and their role in modifying current velocity, sedimentation, and nutrient cycling. To represent these dynamic processes in a numerical model, the presence of SAV and its effect on hydrodynamics (currents and waves) and sediment dynamics was incorporated into the open-source Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) model. In this study, we extend the COAWST modeling framework to account for dynamic changes of SAV and associated epiphyte biomass. Modeled SAV biomass is represented as a function of temperature, light, and nutrient availability. The modeled SAV community exchanges nutrients, detritus, dissolved inorganic carbon, and dissolved oxygen with the water-column biogeochemistry model. The dynamic simulation of SAV biomass allows the plants to both respond to and cause changes in the water column and sediment bed properties, hydrodynamics, and sediment transport (i.e., a two-way feedback). We demonstrate the behavior of these modeled processes through application to an idealized domain and then apply the model to a eutrophic harbor where SAV dieback is a result of anthropogenic nitrate loading and eutrophication. These cases demonstrate an advance in the deterministic modeling of coupled biophysical processes and will further our understanding of future ecosystem change.

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The correlation between iron sulfide precipitation and hypolimnetic phosphorus accumulation during one summer in a softwater lake

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-115 ◽

1995 ◽

Vol 52 (6) ◽

pp. 1190-1194 ◽

Cited By ~ 29

Author(s):

Thomas E. Murray

Keyword(s):

Water Column ◽

Solubility Product ◽

Iron Sulfide ◽

Late Summer ◽

Acid Volatile Sulfide ◽

Overlying Water ◽

Iron Storage ◽

Ferrous Sulfide ◽

Phosphorus Accumulation ◽

Rate Of Accumulation

During late summer, 1992, the water immediately overlying the sediment in the anoxic hypolimnion of Crystal Lake, Conn., was saturated with ferrous sulfide (FeS). The average solubility product (pKsp) at the bottom of the hypolimnion was 3.25, which is consistent with other lake and laboratory studies and is in the range of both amorphous FeS and mackinawite. The precipitation of iron sulfide removed Fe2+ and HS− from the water column, and acid volatile sulfide (AVS) accumulated in the top 6–8 cm of the sediment. Pyrite was formed at deeper depths and did not increase during the study. The accumulation of AVS in the sediment was correlated with an increased accumulation of phosphorus in the water column. The rate of accumulation of phosphorus in the hypolimnion was greatest when iron was lost to the sediment as AVS. The statistically significant link between iron storage in the sediment and phosphorus accumulation in the overlying water suggests that reoxidation of ferrous iron to ferric (hydr)oxides is decreased, and therefore precipitation of ferric phosphate is limited.

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