scholarly journals Ecosystem-Based Restoration to Mitigate Eutrophication: A Case Study in a Shallow Lake

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2141
Author(s):  
Konghao Zhu ◽  
Yao Wu ◽  
Chunhua Li ◽  
Jun Xu ◽  
Min Zhang
Keyword(s):  
Aquatic Macrophytes ◽  
Aquatic Vegetation ◽  
Submerged Macrophytes ◽  
Ecosystem Restoration ◽  
Ecosystem Model ◽  
Eutrophic Lake ◽  
Eutrophic Lakes ◽  
Energy Flows ◽  
The Status

Under the influence of human activities, eutrophication has become an increasingly serious global phenomenon, especially in shallow lakes. Many studies have shown that aquatic macrophytes play a significant role in controlling eutrophication, but only few of these studies are ecosystem based. In this paper, we applied a mass-balance ecosystem model to a shallow eutrophic lake (Lake Datong, China) as a case study with the aims of evaluating the status of ecosystem restoration via the recovery of aquatic vegetation and providing adaptive management suggestions. Results showed that the ecosystem was immature with weak energy flows and nutrient cycling largely due to the excessive submerged macrophytes and the lack of fish as consumer. In the early stages of restoration, the number of fish should be reduced, and aquatic vegetation needs to be recovered to mitigate eutrophication. When the aquatic vegetation community tends to be stable, herbivorous and omnivorous fish should be moderately stocked, and dead aquatic macrophytes should be harvested to maintain the healthy and sustainable development of the ecosystem. This study provided insights for the ecological restoration of shallow eutrophic lakes and revealed the urgent need for ecosystem-based restoration.

Effects of aquatic macrophytes on physico-chemical conditions of three contrasting lowland streams: a consequence of diffuse pollution from agriculture?

2001 ◽  
Vol 43 (5) ◽  
pp. 163-168 ◽  
Author(s):  
R. J. Wilcock ◽  
J. W. Nagels
Keyword(s):  
Aquatic Macrophytes ◽  
Aquatic Vegetation ◽  
Submerged Macrophytes ◽  
Third Stream ◽  
Lowland Streams ◽  
Riparian Plants ◽  
Agricultural Catchments ◽  
Physico Chemical ◽  
Photosynthetic Production ◽  
Chemical Conditions

Three lowland streams in developed pasture catchments with different farming intensities exhibited contrasting summer diurnal variations in pH, DO and temperature. These are ascribed to differences in dominant aquatic vegetation and their respective effects on shade, and on photosynthetic production and respiration within each stream. The stream dominated by submerged macrophytes had the greatest amplitude swings in DO and pH, and DO levels of 86–128% saturation. Floating marginal macrophytes reduced photosynthetic inputs while providing additional organic loading for respiration, with consequent flat DO and pH curves and conditions not conducive to healthy stream ecosystems. The third stream was shaded by riparian plants, which inhibited photosynthetic effects on DO and pH so that diurnal variation was intermediate between the other two streams. The interaction between nutrients and increased insolation in agricultural catchments, in stimulating aquatic plants, needs to be better understood for managing the sustainability of stream habitats and ecosystems.

scholarly journals An attempt to assess the ecological status of a lake based on historical and current maps of submerged vegetation

2017 ◽  
Vol 25 (1) ◽  
pp. 33-42
Author(s):  
Andrzej Hutorowicz ◽  
Marcin Białowąs ◽  
Bronisław Długoszewski ◽  
Lech Doroszczyk
Keyword(s):  
Aquatic Vegetation ◽  
Submerged Macrophytes ◽  
Ecological Status ◽  
Maximum Depth ◽  
Current Status ◽  
Ecological State ◽  
Stratified Lakes ◽  
Analogous Data ◽  
The Status ◽  
Macrophyte Index

Abstract The possibility of doing a back assessment of the ecological status of a lake based on archival bathymetric maps indicating areas overgrown with rushes and aquatic vegetation was verified. This assessment was assumed to be in accordance with that performed with the official Polish macrophyte-based method for lake assessment (Ecological State Macrophyte Index, ESMI). The study was conducted on Lake Dobrąg located in the Warmian-Masurian Voivodeship (surface area - 108 ha, maximum depth - 27.9 m, mean depth - 11.6 m). It included the hydroacoustic distribution of submerged macrophytes along 85 evenly distributed belt transects (perpendicularl to the shore line), creating a bathymetric chart and maps of vegetation occurrence and identifying areas occupied by hydrophytes (Cmax) and the maximum depth of lake colonization (Z). Analogous data were read from archival bathymetric chart dating from 1964-1968. The values obtained were compared with the means (and their confidence intervals) of 83 stratified lakes in Poland in different ecological status classes. Analysis of changes indicated that the ecological status of the lake had deteriorated. In the mid-1960s, the status of the lake was less than “very good” while the current status borders between “good” and “moderate.” The results indicate that the proposed method could be useful when attempting to assess changes in ecological status using archival bathymetric charts showing areas overgrown with vegetation and the distribution of it in lakes.

scholarly journals Diverse role of Macrophytes in aquatic ecosystems: A brief review

2019 ◽  
Vol 19 ◽  
pp. 40-48
Author(s):  
Mitu De ◽  
◽  
Chayanika Roy ◽  
Suchismita Medda ◽  
Sulagna Roy ◽  
...  
Keyword(s):  
Aquatic Ecosystem ◽  
Aquatic Ecosystems ◽  
Aquatic Macrophytes ◽  
Food Source ◽  
Aquatic Vegetation ◽  
Submerged Macrophytes ◽  
Freshwater Ecosystems ◽  
Aquatic Life ◽  
Aquatic Flora

The aquatic ecosystem is composed of aquatic flora and fauna which interact together in maintaining the aquatic ecosystem. Aquatic macrophytes are macroscopic forms of aquatic vegetation, including macro algae, mosses, ferns and angiosperms found in aquatic habitat. Macrophytes of freshwater ecosystems have diverse roles to play in the structure and functioning of these aquatic ecosystems. The depth, density, diversity and types of macrophytes present in a system are indicators of water body health. Aquatic vegetation can influence the water quality too. Macrophytes are considered as an important component of the aquatic ecosystem as the habitat and food source for aquatic life. Of all the biological treatments for controlling eutrophication, submerged macrophytes, has been recognized as being the most effective. This paper is a brief review of the diverse role of macrophytes in an aquatic ecosystem.

Varied Responses to Human-Induced Seismicity in the City of Azle, Texas

2019 ◽  
Vol 3 (1) ◽  
pp. 1-8
Author(s):  
Sarmistha R. Majumdar
Keyword(s):  
State Government ◽  
Induced Seismicity ◽  
Oil And Gas ◽  
The United States ◽  
The State ◽  
Prior History ◽  
Small Community ◽  
Regulatory Policies ◽  
The Status

Fracking has helped to usher in an era of energy abundance in the United States. This advanced drilling procedure has helped the nation to attain the status of the largest producer of crude oil and natural gas in the world, but some of its negative externalities, such as human-induced seismicity, can no longer be ignored. The occurrence of earthquakes in communities located at proximity to disposal wells with no prior history of seismicity has shocked residents and have caused damages to properties. It has evoked individuals’ resentment against the practice of injection of fracking’s wastewater under pressure into underground disposal wells. Though the oil and gas companies have denied the existence of a link between such a practice and earthquakes and the local and state governments have delayed their responses to the unforeseen seismic events, the issue has gained in prominence among researchers, affected community residents, and the media. This case study has offered a glimpse into the varied responses of stakeholders to human-induced seismicity in a small city in the state of Texas. It is evident from this case study that although individuals’ complaints and protests from a small community may not be successful in bringing about statewide changes in regulatory policies on disposal of fracking’s wastewater, they can add to the public pressure on the state government to do something to address the problem in a state that supports fracking.

scholarly journals Discursive Strategies and Sequenced Institutional Change: The Case of Marriage Equality in the United States

2021 ◽  
pp. 003232172110205
Author(s):  
Giulia Mariani ◽  
Tània Verge
Keyword(s):  
United States ◽  
Institutional Change ◽  
The United States ◽  
Marriage Equality ◽  
Agent Based ◽  
Discursive Strategies ◽  
Policy Debates ◽  
The Status ◽  
Private Actors

Building on historical and discursive institutionalism, this article examines the agent-based dynamics of gradual institutional change. Specifically, using marriage equality in the United States as a case study, we examine how actors’ ideational work enabled them to make use of the political and discursive opportunities afforded by multiple venues to legitimize the process of institutional change to take off sequentially through layering, displacement, and conversion. We also pay special attention to how the discursive strategies deployed by LGBT advocates, religious-conservative organizations and other private actors created new opportunities to influence policy debates and tip the scales to their preferred policy outcome. The sequential perspective adopted in this study allows problematizing traditional conceptualizations of which actors support or contest the status quo, as enduring oppositional dynamics lead them to perform both roles in subsequent phases of the institutional change process.

scholarly journals Experimental and Numerical Study of a Microcogeneration Stirling Unit under On–Off Cycling Operation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 801
Author(s):  
Gianluca Valenti ◽  
Aldo Bischi ◽  
Stefano Campanari ◽  
Paolo Silva ◽  
Antonino Ravidà ◽  
...  
Keyword(s):  
Numerical Study ◽  
Thermal Storage ◽  
Primary Energy ◽  
Operational Cost ◽  
Cogeneration Plant ◽  
Economic Optimization ◽  
Viable Option ◽  
Heating Value ◽  
Energy Flows

Stirling units are a viable option for micro-cogeneration applications, but they operate often with multiple daily startups and shutdowns due to the variability of load profiles. This work focused on the experimental and numerical study of a small-size commercial Stirling unit when subjected to cycling operations. First, experimental data about energy flows and emissions were collected during on–off operations. Second, these data were utilized to tune an in-house code for the economic optimization of cogeneration plant scheduling. Lastly, the tuned code was applied to a case study of a residential flat in Northern Italy during a typical winter day to investigate the optimal scheduling of the Stirling unit equipped with a thermal storage tank of diverse sizes. Experimentally, the Stirling unit showed an integrated electric efficiency of 8.9% (8.0%) and thermal efficiency of 91.0% (82.2%), referred to as the fuel lower and, between parenthesis, higher heating value during the on–off cycling test, while emissions showed peaks in NOx and CO up to 100 ppm but shorter than a minute. Numerically, predictions indicated that considering the on–off effects, the optimized operating strategy led to a great reduction of daily startups, with a number lower than 10 per day due to an optimal thermal storage size of 4 kWh. Ultimately, the primary energy saving was 12% and the daily operational cost was 2.9 €/day.

scholarly journals Determinants of judges’ career choices and productivity: a Polish case study

2021 ◽  
Author(s):  
Przemysław Banasik ◽  
Katarzyna Metelska-Szaniawska ◽  
Małgorzata Godlewska ◽  
Sylwia Morawska
Keyword(s):  
Career Choices ◽  
Social Recognition ◽  
District Courts ◽  
Self Monitoring ◽  
Administrative Supervision ◽  
Judicial Efficiency ◽  
The Status ◽  
Service Mission ◽  
The Stability

AbstractThe goal of this paper is to identify factors which affect judges’ productivity and career choice motives with the view of increasing judicial efficiency. Specifically, the investigation focuses on such aspects as judges’ remuneration, promotion, threat of judgment revocation, service/mission, periodic assessment, the threat of a complaint about protracted proceedings or of disciplinary proceedings, the threat of destabilization of the employment relationship, status/prestige of the profession, power/authority, social recognition, leisure, as well as administrative supervision and self-monitoring. To this end, a survey was conducted among judges of three of the largest Polish regional courts and subordinate district courts. The descriptive and statistical analyses show that judges’ care for the number of cases resolved, proxying for their productivity, is significantly correlated with self-monitoring of their adjudication activity. The stability of employment, the status/prestige of the profession and a relatively high remuneration are the most important factors in terms of judges’ career choices. In their care for the number of cases resolved remuneration is, albeit, no longer a relevant factor. Judges monitor their productivity due to reasons other than remuneration, possibly the sense of service/mission and the threat of various adverse consequences, the evidence for which is, however, also rather weak.

scholarly journals Status epilepticus from GABABR antibody positive encephalitis due to de novo mixed small cell and adenocarcinoma of the prostate

2020 ◽  
Vol 13 (11) ◽  
pp. e238172 ◽  
Author(s):  
Christopher Kwan ◽  
Aaron Sia ◽  
Cullen O'Gorman
Keyword(s):  
Status Epilepticus ◽  
De Novo ◽  
Locally Advanced ◽  
Small Cell ◽  
Gamma Aminobutyric Acid ◽  
Transrectal Biopsy ◽  
The Status ◽  
Adenocarcinoma Of The Prostate ◽  
Receptor Antibodies

We present a case study of a 67-year-old man who presented with a new onset of recurrent tonic-clonic seizures. He had tested positive to gamma-aminobutyric acid B receptor antibodies in his blood and cerebrospinal fluid, and subsequent CT imaging and transrectal biopsy confirmed the presence of a locally advanced mixed small cell and Gleason 9 adenocarcinoma of the prostate. His seizures remained resistant to treatment with multiple antiepileptic drugs, including sodium valproate, clobazam, topiramate, carbamazepine, phenytoin and lacosamide. He progressed to status epilepticus, which required intravenous immunoglobulin and steroids, followed by plasma exchange 1 week later. The status epilepticus was refractory and required multiple admissions to the intensive care unit.

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