scholarly journals The role of sediment-induced light attenuation on primary production during Hurricane Gustav (2008)

2020 ◽  
Vol 17 (20) ◽  
pp. 5043-5055
Author(s):  
Zhengchen Zang ◽  
Z. George Xue ◽  
Kehui Xu ◽  
Samuel J. Bentley ◽  
Qin Chen ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Chlorophyll Concentration ◽  
Light Attenuation ◽  
Sediment Concentration ◽  
Biogeochemical Model ◽  
System A ◽  
Sensitivity Tests ◽  
The Impact

Abstract. We introduced a sediment-induced light attenuation algorithm into a biogeochemical model of the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. A fully coupled ocean–atmospheric–sediment–biogeochemical simulation was carried out to assess the impact of sediment-induced light attenuation on primary production in the northern Gulf of Mexico during the passage of Hurricane Gustav in 2008. When compared with model results without sediment-induced light attenuation, our new model showed a better agreement with satellite data on both the magnitude of nearshore chlorophyll concentration and the spatial distribution of offshore bloom. When Hurricane Gustav approached, resuspended sediment shifted the inner shelf ecosystem from a nutrient-limited one to a light-limited one. Only 1 week after Hurricane Gustav's landfall, accumulated nutrients and a favorable optical environment induced a posthurricane algal bloom in the top 20 m of the water column, while the productivity in the lower water column was still light-limited due to slow-settling sediment. Corresponding with the elevated offshore NO3 flux (38.71 mmol N m−1 s−1) and decreased chlorophyll flux (43.10 mg m−1 s−1), the outer shelf posthurricane bloom should have resulted from the cross-shelf nutrient supply instead of the lateral dispersed chlorophyll. Sensitivity tests indicated that sediment light attenuation efficiency affected primary production when sediment concentration was moderately high. Model uncertainties due to colored dissolved organic matter and parameterization of sediment-induced light attenuation are also discussed.

scholarly journals The Role of Sediment-induced Light Attenuation on Primary Production during Hurricane Gustav (2008)

2020 ◽  
Author(s):  
Zhengchen Zang ◽  
Z. George Xue ◽  
Kehui Xu ◽  
Samuel J. Bentley ◽  
Qin Chen ◽  
...  
Keyword(s):  
Primary Production ◽  
Chlorophyll Concentration ◽  
Light Attenuation ◽  
Sediment Concentration ◽  
Ocean Modeling ◽  
Biogeochemical Model ◽  
Regional Ocean Modeling System ◽  
Sensitivity Tests ◽  
Lower Column ◽  
The Impact

Abstract. We introduce a sediment-induced light attenuation algorithm into the biogeochemical model of the Regional Ocean Modeling System (ROMS). A fully coupled ocean-atmospheric-sediment-biogeochemical simulation is carried out to assess the impact of sediment-induced light attenuation on primary production in the northern Gulf of Mexico during Hurricane Gustav in 2008. The new model shows a better agreement with satellite data on both the magnitude of nearshore chlorophyll concentration and the distribution of offshore bloom. When Gustav approaches, resuspended sediments shift the inner shelf ecosystem from a nutrient-limited one to light-limited. One week after Gustav’s landfall, accumulated nutrient and favorable optical environment induces a post-hurricane algal bloom in the top 20 m of water column, while the productivity in the lower column is still light-limited due to unsettled sediment. Corresponding with the elevated offshore NO3 flux (38.71 mmol N/m/s) and decreased chlorophyll flux (43.10 mg/m/s), the post-hurricane bloom in the outer shelf is resulted from the cross-shelf nutrient supply instead of the lateral dispersed chlorophyll. Sensitivity tests indicate sediment light attenuation efficiency affects primary production when sediment concentration is moderately high.

scholarly journals Effects of large-scale floating (solar photovoltaic) platforms on hydrodynamics and primary production in a coastal sea from a water column model

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 195-208
Author(s):  
Thodoris Karpouzoglou ◽  
Brigitte Vlaswinkel ◽  
Johan van der Molen
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Large Scale ◽  
Net Primary Production ◽  
Biogeochemical Model ◽  
Solar Photovoltaic ◽  
Column Model ◽  
Coastal Sea ◽  
Floating Platforms ◽  
The Impact

Abstract. An improved understanding of the effects of floating solar platforms on the ecosystem is necessary to define acceptable and responsible real-world field implementations of this new marine technology. This study examines a number of potential effects of offshore floating solar photovoltaic (PV) platforms on the hydrodynamics and net primary production in a coastal sea for the first time. Three contrasting locations within the North Sea (a shallow and deeper location with well-mixed conditions and a seasonally stratifying location) have been analysed using a water column physical–biogeochemical model: the General Ocean Turbulence Model coupled with the European Regional Seas Ecosystem Model – Biogeochemical Flux Model (GOTM-ERSEM-BFM). The results show strong dependence on the characteristics of the location (e.g. mixing and stratification) and on the density of coverage with floating platforms. The overall response of the system was separated into contributions by platform-induced light deficit, shielding by the platforms of the sea surface from wind and friction induced by the platforms on the currents. For all three locations, light deficit was the dominant effect on the net primary production. For the two well-mixed locations, the other effects of the platforms resulted in partial compensation for the impact of light deficit, while for the stratified location, they enhanced the effects of light deficit. For up to 20 % coverage of the model surface with platforms, the spread in the results between locations was relatively small, and the changes in net primary production were less than 10 %. For higher percentages of coverage, primary production decreased substantially, with an increased spread in response between the sites. The water column model assumes horizontal homogeneity in all forcings and simulated variables, also for coverage with floating platforms, and hence the results are applicable to very-large-scale implementations of offshore floating platforms that are evenly distributed over areas of at least several hundreds of square kilometres, such that phytoplankton remain underneath a farm throughout several tidal cycles. To confirm these results, and to investigate more realistic cases of floating platforms distributed unevenly over much smaller areas with horizontally varying hydrodynamic conditions, in which phytoplankton can be expected to spend only part of the time underneath a farm and effects are likely to be smaller, spatial detail and additional processes need to be included. To do so, further work is required to advance the water column model towards a three-dimensional modelling approach.

scholarly journals Effects of floating (solar PV) platforms on hydrodynamics and primary production in a coastal sea

2019 ◽  
Author(s):  
Thodoris Karpouzoglou ◽  
Brigitte Vlaswinkel ◽  
Johan van der Molen
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Net Primary Production ◽  
Strong Dependence ◽  
Biogeochemical Model ◽  
Solar Pv ◽  
Column Model ◽  
Coastal Sea ◽  
Floating Platforms ◽  
The Impact

Abstract. An improved understanding of the effects of floating solar platforms on the ecosystem is necessary to define acceptable and responsible real-world field implementations of this new marine technology. This study examines a number of potential effects of offshore floating solar PV platforms on the hydrodynamics and net primary production in a coastal sea for the first time. Three contrasting locations within the North Sea (a shallow and deeper location with well-mixed conditions and a summer-stratifying location) have been analysed using a water column physical-biogeochemical model (GOTM-ERSEM-BFM). The results show strong dependence on the characteristics of the location (e.g. mixing and stratification) and on the density of coverage with floating platforms. The overall response of the system was separated into contributions by platform shadow, shielding by the platforms of the sea surface from wind, and friction induced by the platforms on the currents. For all three locations, platform shadow was the dominant effect on the net primary production. For the two well-mixed locations, the other effects of the platforms resulted in partial compensation for the impact of platform shadow, while for the stratified location, they enhanced the effects of platform shadow. For up to 20 % coverage of the model surface with platforms, the spread in the results between locations was relatively small, and the changes in net primary production were less than 10 %. For higher percentages of coverage, primary production decreased substantially, with an increased spread in response between the sites. The water-column model assumes horizontal homogeneity in all forcings and simulated variables, also for coverage with floating platforms, and hence the results are applicable to very large-scale implementations of offshore floating platforms that are evenly distributed over areas of at least several hundreds of square kilometres. To confirm these results, and to investigate more realistic cases of floating platforms distributed unevenly over much smaller areas with horizontally varying hydrodynamic conditions, in which phytoplankton can be expected to spend only part of the time underneath a farm, spatial detail and additional processes need to be included. To do so, further work is required to advance the water-column model towards a 3D modelling approach.

scholarly journals WUJUD BUDAYA DALAM NOVEL TEGUH ANAK JADAH KARYA A.D. DONGGO (KAJIAN ANTROPOLOGI SASTRA)

EDU-KATA ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 159-168
Author(s):  
Amiruddin Amiruddin
Keyword(s):  
New Order ◽  
Physical Culture ◽  
The Novel ◽  
Value System ◽  
System A ◽  
A Value ◽  
The Family ◽  
Anthropological Literature ◽  
The Impact

This research-oriented culture and a form of resistance against the culture of power in the novel Teguh Anak Jadah by A.D. Donggo studied from anthropological literature review. Interdisciplinary between anthropology and literature provide new understanding of the phenomenon of human culture in literature. The method used in this study using hermeneutic methods. This method outlined understand the text and the text intended for a review of literature. Hermeneutical suitable for reading literature for the study of literature, whatever its form, related to an activity that interpretation.  In general, the study found a form of culture and a form of resistance against the culture of power in the novel Teguh Anak Jadah by A.D. Donggo. Cultural manifestation in the form of a value system, a system of norms, physical culture, specific rules, politics cultural activities, and the work. Novel Teguh Anak Jadah by A.D. Donggo It also shows the impact of the New Order regime and its cronies make public mindset when it becomes depressed, silent habit deeply ingrained during the New Order government has given rise to a new habit that is easy to forget. Forgetting the role of self, the role of the organization, the role of the family, against fellow citizens of different ideologies.

scholarly journals Seabed Resuspension in the Chesapeake Bay: Implications for Biogeochemical Cycling and Hypoxia

2020 ◽  
Vol 44 (1) ◽  
pp. 103-122
Author(s):  
Julia M. Moriarty ◽  
Marjorie A. M. Friedrichs ◽  
Courtney K. Harris
Keyword(s):  
Organic Matter ◽  
Chesapeake Bay ◽  
Water Column ◽  
Primary Productivity ◽  
Environmental Changes ◽  
Light Attenuation ◽  
Sediment Resuspension ◽  
Nitrogen Dynamics ◽  
Biogeochemical Model ◽  
Order Of Magnitude

AbstractSediment processes, including resuspension and transport, affect water quality in estuaries by altering light attenuation, primary productivity, and organic matter remineralization, which then influence oxygen and nitrogen dynamics. The relative importance of these processes on oxygen and nitrogen dynamics varies in space and time due to multiple factors and is difficult to measure, however, motivating a modeling approach to quantify how sediment resuspension and transport affect estuarine biogeochemistry. Results from a coupled hydrodynamic–sediment transport–biogeochemical model of the Chesapeake Bay for the summers of 2002 and 2003 showed that resuspension increased light attenuation, especially in the northernmost portion of the Bay, shifting primary production downstream. Resuspension also increased remineralization in the central Bay, which experienced larger organic matter concentrations due to the downstream shift in primary productivity and estuarine circulation. As a result, oxygen decreased and ammonium increased throughout the Bay in the bottom portion of the water column, due to reduced photosynthesis in the northernmost portion of the Bay and increased remineralization in the central Bay. Averaged over the channel, resuspension decreased oxygen by ~ 25% and increased ammonium by ~ 50% for the bottom water column. Changes due to resuspension were of the same order of magnitude as, and generally exceeded, short-term variations within individual summers, as well as interannual variability between 2002 and 2003, which were wet and dry years, respectively. Our results quantify the degree to which sediment resuspension and transport affect biogeochemistry, and provide insight into how coastal systems may respond to management efforts and environmental changes.

A model for the light-limited growth of buoyant phytoplankton in a shallow, turbid waterbody

1994 ◽  
Vol 45 (5) ◽  
pp. 847 ◽  
Author(s):  
BE Sherman ◽  
IT Webster
Keyword(s):  
Wind Speed ◽  
Water Column ◽  
Chlorophyll Concentration ◽  
Light Attenuation ◽  
Euphotic Zone ◽  
Limited Growth ◽  
Potential Growth ◽  
Column Temperature ◽  
Turbid Waters ◽  
Neutrally Buoyant

A computer model was used to explore the relationship between buoyancy and the light-limited growth of phytoplankton in very turbid waters. The model simulates the potential growth of phytoplankton as a function of flotation speed, using field observations of photosynthetically active radiation, wind speed, surface-layer thickness (from water-column temperature data), and light attenuation made at Rushy Billabong on the River Murray from 28 November 1991 to 26 March 1992. A unique feature of the model is the simulation of the development and dispersal of surface scums as a function of wind speed. Under nutrient-replete conditions, the model predicted that phytoplankton with a flotation speed of 1-10 m day-1 (typical of Anabaena flos-aquae and Microcystis aeruginosa) would grow up to four times faster than would neutrally buoyant phytoplankton with the same maximum specific growth rate. In the shallow system modelled, high flotation speeds allowed a large proportion of the total population to rise into the euphotic zone shortly after the onset of stratification each day. Surface scums played an important role in maintaining the more buoyant phytoplankton populations close to the water surface. Under the very turbid conditions in the billabong (100 nephelometric turbidity units), self-shading became significant only when the mean chlorophyll concentration in the water column approached 100 mg chla m-3.

Controls on oxygen response to climate change on the Northwest European Continental Shelf

2020 ◽  
Author(s):  
Sarah L. Wakelin ◽  
Yuri Artioli ◽  
Momme Butenschön ◽  
Jason Holt ◽  
Jeremy Blackford
Keyword(s):  
Climate Change ◽  
Continental Shelf ◽  
Water Column ◽  
Ecosystem Processes ◽  
Phytoplankton Production ◽  
Biogeochemical Model ◽  
Biological Cycling ◽  
Increasing Temperature ◽  
The Impact ◽  
Oxygen Concentrations

<p>Dissolved oxygen in the ocean is an indicator of water quality and low concentrations can threaten ecosystem health. The main sources of marine oxygen are diffusion from the atmosphere and phytoplankton photosynthesis. Biological respiration and decomposition act to reduce oxygen concentrations. Under conditions of vertical stratification, the water column below the pycnocline is isolated from oxygen exchange with the atmosphere, photosynthesis may be limited by light availability and oxygen concentrations decrease. Climate change influences the oxygen cycle in two ways: 1) changing the hydrodynamic climate and 2) affecting rates of biogeochemical processes. The hydrodynamic climate affects the nutrient supply and so controls phytoplankton production while changes to water column stratification affects vertical mixing. Gas solubility decreases with increasing temperature so that oxygen uptake from the atmosphere is expected to decrease under increasing oceanic temperatures. Biological cycling rates increase with increasing temperature affecting photosynthesis, respiration and bacterial decomposition. It is not obvious whether changes in oxygen concentrations due to changing ecosystem processes will mitigate or reinforce the projected reduction from solubility changes.</p><p>The Northwest European Continental shelf (NWES) is a region of the northeast Atlantic that experiences seasonal stratification. We use the physics-biogeochemical model NEMO-ERSEM to study near-bed oxygen concentrations on the NWES under a high greenhouse gas emissions scenario (Representative Concentration Pathway (RCP) 8.5). We show that much of the NWES could experience low oxygen concentrations by 2100 and assess the relative impacts of changing temperature and ecosystem processes. Until about 2040 the impact of solubility dominates the oxygen change. The mean near-bed oxygen concentration is projected to decrease by 6.3% by 2100, of which 73% is due to solubility changes and the remainder to changes in the ecosystem. In the oxygen-depleted region in the eastern North Sea, 77% of the near-bed oxygen reduction is due to ecosystem processes.</p>

scholarly journals Modeling the Pathways and Accumulation Patterns of Micro- and Macro-Plastics in the Mediterranean

2021 ◽  
Vol 8 ◽  
Author(s):  
Kostas Tsiaras ◽  
Yannis Hatzonikolakis ◽  
Sofia Kalaroni ◽  
Annika Pollani ◽  
George Triantafyllou
Keyword(s):  
Water Column ◽  
Wind Wave ◽  
Hot Spot ◽  
Sea Surface ◽  
Biogeochemical Model ◽  
Near Surface ◽  
Size Classes ◽  
Basin Scale ◽  
The Mediterranean ◽  
The Impact

The Mediterranean is considered a hot-spot for plastic pollution, due to its semi-enclosed nature and heavily populated coastal areas. In the present study, a basin-scale coupled hydrodynamic/particle drift model was used to track the pathways and fate of plastics from major land-based sources (coastal cities and rivers), taking into account of the most important processes (advection, stokes drift, vertical and horizontal mixing, sinking, wind drag, and beaching). A hybrid ensemble Kalman filter algorithm was implemented to correct the near- surface circulation, assimilating satellite data (sea surface height, temperature) in the hydrodynamic model. Different size classes and/or types of both micro- and macroplastics were considered in the model. Biofouling induced sinking was explicitly described, as a possible mechanism of microplastics removal from the surface. A simplified parameterization of size-dependent biofilm growth has been adopted, as a function of bacterial biomass (obtained from a biogeochemical model simulation), being considered a proxy for the biofouling community. The simulated distributions for micro- and macroplastics were validated against available observations, showing reasonable agreement, both in terms of magnitude and horizontal variability. An 8-year simulation was used to identify micro- and macroplastics accumulation patterns in the surface layer, water column, seafloor and beaches. The impact of different processes (vertical mixing, biofouling, and wind/wave drift) was identified through a series of sensitivity experiments. For both micro- and macroplastics, distributions at sea surface were closely related to the adopted sources. The microplastics concentration was drastically reduced away from source areas, due to biofouling induced sinking, with their size distribution dominated by larger (>1 mm) size classes in open sea areas, in agreement with observations. High concentration patches of floating plastics were simulated in convergence areas, characterized by anticyclonic circulation. The distribution of macroplastics on beaches followed the predominant southeastward wind/wave direction. In the water column, a sub-surface maximum in microplastics abundance was simulated, with increasing contribution of smaller particles in deeper layers. Accumulation of microplastics on the seafloor was limited in relatively shallow areas (<500 m), with bottom depth below their relaxation depth due to defouling. The simulated total amount of floating plastics (∼3,760 tonnes) is comparable with estimates from observations.

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