The Role of Estuarine Modeling in Nutrient Control

1988 ◽  
Vol 20 (6-7) ◽  
pp. 243-252 ◽  
Author(s):  
Wu-Seng Lung
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Wastewater Treatment Plants ◽  
Substantial Reduction ◽  
Nitrogen Fixing ◽  
Variable Model ◽  
Species Dominance ◽  
Green Algal ◽  
Limiting Condition ◽  
The Impact

Two case studies are presented to demonstrate how estuarine water quality models can be used in planning eutrophication control. In the first study, a steady-state model is used to assess the impact of point source phosphorus reduction on the phytoplankton biomass in the upper James Estuary in Virginia during the summer months. The modeling results indicate that phosphorus is in ample supply to support the phytoplankton growth in the system. However, substantial reduction of loads by phosphorus removal at the wastewater treatment plants would lead to a phosphorus limiting condition thereby lowering the phytoplankton biomass levels. In the second study, a time-variable model is developed to investigate the potential of blue-green algal (Microcystis) blooms in the Neuse Estuary in North Carolina. More specifically, the model is designed to address two management questions. First, recognizing that high nonpoint nitrogen loads in the spring months would lead to a proliferation of non-nitrogen fixing blue-green genera, should parallel control of nitrogen be considered? Second, in light of the potential for algae species dominance to shift, is control of nitrogen fixing blue-green algal blooms possible? Based on the modeling calibration results using data from 1983, 1984 and 1985 under different hydrologic conditions, freshwater flow to the estuary is found to be a key factor in controlling blue-green algal blooms in the Neuse Estuary.

How Can We Use Fluorescence And Artificial Intelligence To Better Control Blue-Green Algal Blooms?

2018 ◽  
Author(s):  
Edoardo Bertone ◽  
Michele A. Burford ◽  
David P. Hamilton
Keyword(s):  
Artificial Intelligence ◽  
Algal Blooms ◽  
Green Algal

scholarly journals Effects of the Marine Biotoxins Okadaic Acid and Dinophysistoxins on Fish

2021 ◽  
Vol 9 (3) ◽  
pp. 293
Author(s):  
Mauro Corriere ◽  
Lucía Soliño ◽  
Pedro Reis Costa
Keyword(s):  
Okadaic Acid ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Current Knowledge ◽  
Global Climate ◽  
Scientific Evidence ◽  
Shellfish Poisoning ◽  
Morphological Alterations ◽  
The Impact ◽  
Dsp Toxins

Natural high proliferations of toxin-producing microorganisms in marine and freshwater environments result in dreadful consequences at the socioeconomically and environmental level due to water and seafood contamination. Monitoring programs and scientific evidence point to harmful algal blooms (HABs) increasing in frequency and intensity as a result of global climate alterations. Among marine toxins, the okadaic acid (OA) and the related dinophysistoxins (DTX) are the most frequently reported in EU waters, mainly in shellfish species. These toxins are responsible for human syndrome diarrhetic shellfish poisoning (DSP). Fish, like other marine species, are also exposed to HABs and their toxins. However, reduced attention has been given to exposure, accumulation, and effects on fish of DSP toxins, such as OA. The present review intends to summarize the current knowledge of the impact of DSP toxins and to identify the main issues needing further research. From data reviewed in this work, it is clear that exposure of fish to DSP toxins causes a range of negative effects, from behavioral and morphological alterations to death. However, there is still much to be investigated about the ecological and food safety risks related to contamination of fish with DSP toxins.

scholarly journals Response of ocean phytoplankton community structure to climate change over the 21st century: partitioning the effects of nutrients, temperature and light

2010 ◽  
Vol 7 (12) ◽  
pp. 3941-3959 ◽  
Author(s):  
I. Marinov ◽  
S. C. Doney ◽  
I. D. Lima
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Sea Ice ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Vertical Mixing ◽  
Phytoplankton Community Structure ◽  
Marginal Sea ◽  
Small Phytoplankton ◽  
The Impact

Abstract. The response of ocean phytoplankton community structure to climate change depends, among other factors, upon species competition for nutrients and light, as well as the increase in surface ocean temperature. We propose an analytical framework linking changes in nutrients, temperature and light with changes in phytoplankton growth rates, and we assess our theoretical considerations against model projections (1980–2100) from a global Earth System model. Our proposed "critical nutrient hypothesis" stipulates the existence of a critical nutrient threshold below (above) which a nutrient change will affect small phytoplankton biomass more (less) than diatom biomass, i.e. the phytoplankton with lower half-saturation coefficient K are influenced more strongly in low nutrient environments. This nutrient threshold broadly corresponds to 45° S and 45° N, poleward of which high vertical mixing and inefficient biology maintain higher surface nutrient concentrations and equatorward of which reduced vertical mixing and more efficient biology maintain lower surface nutrients. In the 45° S–45° N low nutrient region, decreases in limiting nutrients – associated with increased stratification under climate change – are predicted analytically to decrease more strongly the specific growth of small phytoplankton than the growth of diatoms. In high latitudes, the impact of nutrient decrease on phytoplankton biomass is more significant for diatoms than small phytoplankton, and contributes to diatom declines in the northern marginal sea ice and subpolar biomes. In the context of our model, climate driven increases in surface temperature and changes in light are predicted to have a stronger impact on small phytoplankton than on diatom biomass in all ocean domains. Our analytical predictions explain reasonably well the shifts in community structure under a modeled climate-warming scenario. Climate driven changes in nutrients, temperature and light have regionally varying and sometimes counterbalancing impacts on phytoplankton biomass and structure, with nutrients and temperature dominant in the 45° S–45° N band and light-temperature effects dominant in the marginal sea-ice and subpolar regions. As predicted, decreases in nutrients inside the 45° S–45° N "critical nutrient" band result in diatom biomass decreasing more than small phytoplankton biomass. Further stratification from global warming could result in geographical shifts in the "critical nutrient" threshold and additional changes in ecology.

Implementation of Self-Organizing Maps (SOM) to analyses of environmental parameters and phytoplankton biomass in a macrotidal estuary and artificial lake

2012 ◽  
Vol 93 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Roksana Jahan ◽  
Hyu Chang Choi ◽  
Young Seuk Park ◽  
Young Cheol Park ◽  
Ji Ho Seo ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Suspended Solids ◽  
Inorganic Nitrogen ◽  
Environmental Parameters ◽  
Ecological Data ◽  
Self Organizing Maps ◽  
Macrotidal Estuary ◽  
Phytoplankton Communities ◽  
Self Organizing

Self-Organizing Maps (SOM) have been used for patterning and visualizing ten environmental parameters and phytoplankton biomass in a mactrotidal (>10 m) Gyeonggi Bay and artificial Shihwa Lake during 1986–2004. SOM segregated study areas into four groups and ten subgroups. Two strikingly alternative states are frequently observed: the first is a diverse non-eutrophic state designated by three groups (SOM 1–3), and the second is a eutrophic state (SOM 4: Shihwa Lake and Upper Gyeonggi Bay; summer season) characterized by enhanced nutrients (3 mg l−1 dissolved inorganic nitrogen, 0.1 mg l−1 PO4) that act as a signal and response to that signal as algal blooms (24 µg chlorophyll-a l−1). Bloom potential in response to nitrification is affiliated with high temperature (r = 0.26), low salinity (r = −0.40) and suspended solids (r = –0.27). Moreover, strong stratification in the Shihwa Lake has accelerated harmful algal blooms and hypoxia. The non-eutrophic states (SOM 1–3) are characterized by macro-tidal estuaries exhibiting a tolerance to pollution with nitrogen-containing nutrients and retarding any tendency toward stratification. SOM 1 (winter) is more distinct from SOM 4 due to higher suspended solids (>50 mg l−1) caused by resuspension that induces light limitation and low chlorophyll-a (<5 µg l−1). In addition, eutrophication-induced shifts in phytoplankton communities are noticed during all the seasons in Gyeonggi Bay. Overall, SOM showed high performance for visualization and abstraction of ecological data and could serve as an efficient ecological map that can specify blooming regions and provide a comprehensive view on the eutrophication process in a macrotidal estuary.

Nitrification preservation in activated sludge during curative bulking chlorination

2003 ◽  
Vol 47 (11) ◽  
pp. 85-92 ◽  
Author(s):  
E. Cotteux ◽  
P. Duchene
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Oxygen Uptake Rate ◽  
Ammonia Concentration ◽  
Synthetic Wastewater ◽  
Biological Wastewater Treatment ◽  
Simple Method ◽  
Method Of Measurement ◽  
The Impact

The bulking that occurs in biological wastewater treatment plants using activated sludge is very often controlled by the injection of sodium hypochlorite into the return activated sludge (RAS) stream. In the present study undertaken at two pilot plants fed with synthetic wastewater, the impact of the pass frequency of the sludge at the chlorine dosing point on the nitrifying flora is analysed. The pass frequency is one for the pilot plant 1 and two for the pilot plant 2. A dose of chlorine of 4.85 ± 0.05 g/kg/MLVSS per day was applied at both pilots. The preservative effect on nitrifying activity of the lowest concentration of chlorine at the dosing point and therefore of the highest pass frequency was evidenced. Among other tools, a simple method of measurement of the oxygen uptake rate enabled us to monitor the effect of chlorination on nitrification before recording an increase in the ammonia concentration in the bulking.

The impact of pesticides on arbuscular mycorrhizal and nitrogen-fixing symbioses in legumes

2000 ◽  
Vol 14 (3) ◽  
pp. 191-200 ◽  
Author(s):  
Mohamed Hemida Abd-Alla ◽  
Shukry Ahmed Omar ◽  
Sokol Karanxha
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Nitrogen Fixing ◽  
The Impact ◽  
Impact Of Pesticides

scholarly journals 47 COVID-19 Impact on Burn Care- A Summary of Weekly Bed Counts and Surge Capacity

2021 ◽  
Vol 42 (Supplement_1) ◽  
pp. S35-S35
Author(s):  
Jeffrey E Carter ◽  
Herbert Phelan ◽  
Colleen M Ryan ◽  
James C Jeng ◽  
Kathryn Mai ◽  
...  
Keyword(s):  
Substantial Reduction ◽  
Surge Capacity ◽  
Burn Centers ◽  
Resource Limitations ◽  
Burn Care ◽  
Regional Trends ◽  
Number Of Patients ◽  
Bed Capacity ◽  
Initial Survey ◽  
The Impact

Abstract Introduction The COVID-19 pandemic has raised global awareness of healthcare resource limitations. Specifically, the pandemic has demonstrated that burn disaster planning should involve non-burn disasters that threaten staff, supplies, or space. The ABA facilitated bed counts with the assistance of regional disaster coordinators from April through August of 2020. Our analysis examines the impact of the pandemic on burn surge and bed capacity in the U.S. Methods Bed availability was obtained by the ABA regional disaster coordinators through an initiative by the Organization and Delivery of Burn Care Committee. Bed availability was defined as immediately available burn beds and categorized as adult, pediatric, or flexible. Surge capacity was defined as the maximum number of patients that a burn center could admit in a surge situation. Data was deidentified by the central office with descriptive statistics to determine bed availability and surge capacity trends regionally and nationally. Results Bed counts were performed 6 times from 04/17/2020 through 08/14/2020. Response rates from the 137 North American burn centers varied from 86–96%. At least 6 burn centers (5%) were either closed or converted for COVID patients during the initial two bed counts. The total number of adult or pediatric burn beds was 2,082. Total bed availability decreased from 845 at the first survey down to 572 beds at the last survey. Surge capacity baseline was 1,668 beds and decreased from 1,132 beds in the initial survey down to 833 beds in the final survey. Conclusions Our study demonstrates a significant impact on burn bed availability due to the COVID-19 pandemic with a 37% reduction in available burn beds from April to August and a 26% reduction in surge capacity. This study demonstrates a substantial reduction in bed availability during the pandemic with additional analysis in process to examine regional trends.

scholarly journals Paraben Compounds—Part I: An Overview of Their Characteristics, Detection, and Impacts

2021 ◽  
Vol 11 (5) ◽  
pp. 2307
Author(s):  
João Lincho ◽  
Rui C. Martins ◽  
João Gomes
Keyword(s):  
Scientific Community ◽  
Wastewater Treatment Plants ◽  
Analytical Techniques ◽  
Water Sources ◽  
Human Tissues ◽  
Antimicrobial Compounds ◽  
Toxicological Studies ◽  
The Impact ◽  
Different Sources ◽  
Different Water Sources

Parabens are widely used in different industries as preservatives and antimicrobial compounds. The evolution of analytical techniques allowed the detection of these compounds in different sources at µg/L and ng/L. Until today, parabens were already found in water sources, air, soil and even in human tissues. The impact of parabens in humans, animals and in ecosystems are a matter of discussion within the scientific community, but it is proven that parabens can act as endocrine disruptors, and some reports suggest that they are carcinogenic compounds. The presence of parabens in ecosystems is mainly related to wastewater discharges. This work gives an overview about the paraben problem, starting with their characteristics and applications. Moreover, the dangers related to their usage were addressed through the evaluation of toxicological studies over different species as well as of humans. Considering this, paraben detection in different water sources, wastewater treatment plants, humans and animals was analyzed based on literature results. A review of European legislation regarding parabens was also performed, presenting some considerations for the use of parabens.

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