Development of a water temperature-ecological model to stimulate global warming effects on lake ecosystem

1996 ◽  
Vol 34 (7-8) ◽  
Keyword(s):  
Global Warming ◽  
Water Temperature ◽  
Ecological Model ◽  
Lake Ecosystem

Development of a water temperature-ecological model to stimulate global warming effects on lake ecosystem

1996 ◽  
Vol 34 (7-8) ◽  
pp. 237-244 ◽  
Author(s):  
Masaaki Hosomi ◽  
Tetsu Saigusa ◽  
Kenichi Yabunaka ◽  
Takuya Okubo ◽  
Akihiko Murakami
Keyword(s):  
Global Warming ◽  
Water Temperature ◽  
Thermal Stratification ◽  
Ecological Model ◽  
Nutrient Release ◽  
Eddy Diffusion ◽  
Nutrient Concentrations ◽  
Lake Ecosystem ◽  
Phytoplankton Species ◽  
Freezing And Thawing

This paper describes a newly developed combined water temperature-ecological (WT-ECO) model which is employed to simulate the effects of global warming on lake and reservoir ecosystems. The WT model includes (i) variations in the eddy diffusion coefficient based on the degree of thermal stratification and the velocity of wind, and (ii) a sub-model for simulating the freezing and thawing processes of surface water, water temperatures, and the mixing rates between two adjacent layers of water. The ECO model then uses these results to calculate the resultant effect on a lake's ecological dynamics, e.g., composition of phytoplankton species, their respective concentrations, and nutrient concentrations. When the model was benchmarked against Lake Yunoko, a dimictic lake, fairly good agreement was obtained over a 4-yr period; thereby indicating it is suitably calibrated. In addition, to assess the effects of global warming on a lake ecosystem, changes in Lake Yunoko's water temperature/quality were simulated in response to an increase in air temperature of 2 - 4°C. Results indicate that such an increase will (i) increase thermal stratification in summer, which increases the nutrient concentrations in bottom water due to nutrient release from bottom sediment, (ii) increase the concentration of phytoplankton at the beginning of the autumn circulation period, and (iii) change the composition of phytoplankton species.

scholarly journals High net CO<sub>2</sub> and CH<sub>4</sub> release at a eutrophic shallow lake on a formerly drained fen

2016 ◽  
Vol 13 (10) ◽  
pp. 3051-3070 ◽  
Author(s):  
Daniela Franz ◽  
Franziska Koebsch ◽  
Eric Larmanou ◽  
Jürgen Augustin ◽  
Torsten Sachs
Keyword(s):  
Global Warming ◽  
Shallow Lake ◽  
Typha Latifolia ◽  
Open Water ◽  
Emergent Vegetation ◽  
Lake Ecosystem ◽  
Co2 Uptake ◽  
Mild Winter ◽  
Ch4 Emissions ◽  
Northeastern Germany

Abstract. Drained peatlands often act as carbon dioxide (CO2) hotspots. Raising the groundwater table is expected to reduce their CO2 contribution to the atmosphere and revitalise their function as carbon (C) sink in the long term. Without strict water management rewetting often results in partial flooding and the formation of spatially heterogeneous, nutrient-rich shallow lakes. Uncertainties remain as to when the intended effect of rewetting is achieved, as this specific ecosystem type has hardly been investigated in terms of greenhouse gas (GHG) exchange. In most cases of rewetting, methane (CH4) emissions increase under anoxic conditions due to a higher water table and in terms of global warming potential (GWP) outperform the shift towards CO2 uptake, at least in the short term.Based on eddy covariance measurements we studied the ecosystem–atmosphere exchange of CH4 and CO2 at a shallow lake situated on a former fen grassland in northeastern Germany. The lake evolved shortly after flooding, 9 years previous to our investigation period. The ecosystem consists of two main surface types: open water (inhabited by submerged and floating vegetation) and emergent vegetation (particularly including the eulittoral zone of the lake, dominated by Typha latifolia). To determine the individual contribution of the two main surface types to the net CO2 and CH4 exchange of the whole lake ecosystem, we combined footprint analysis with CH4 modelling and net ecosystem exchange partitioning.The CH4 and CO2 dynamics were strikingly different between open water and emergent vegetation. Net CH4 emissions from the open water area were around 4-fold higher than from emergent vegetation stands, accounting for 53 and 13 g CH4 m−2 a−1 respectively. In addition, both surface types were net CO2 sources with 158 and 750 g CO2 m−2 a−1 respectively. Unusual meteorological conditions in terms of a warm and dry summer and a mild winter might have facilitated high respiration rates. In sum, even after 9 years of rewetting the lake ecosystem exhibited a considerable C loss and global warming impact, the latter mainly driven by high CH4 emissions. We assume the eutrophic conditions in combination with permanent high inundation as major reasons for the unfavourable GHG balance.

The Global Warming By Using The Experimental Methods Within Project-Based Learning Approach

2020 ◽  
Author(s):  
Gulperi Selcan Öncü
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Greenhouse Gases ◽  
Water Temperature ◽  
Forest Fires ◽  
Experimental Methods ◽  
Project Based Learning ◽  
Control Group ◽  
Learning Approaches ◽  
The Impact

&lt;div&gt; &lt;p&gt;In recent times we have often received news such as about melting glaciers, sudden and torrential rain, storms, increased atmospheric temperatures, and forest fires. We have also observed some of these phenomena in our immediate vicinity. There is a frequently used expression among the public, 'the seasons are shifting'.&amp;#160;&lt;/p&gt; &lt;p&gt;Students have asked the reasons why these changes have been occurring and what about changes between the past and present. In order to understand these changes we all know that they need to understand global warming in the first place. To help them with this as an science teacher I have guided them to be capable of using experimental methods within project-based learning approaches. First they did preliminary literature surveys and then they designed an experiment. In the experiment, they tested the hypothesis that the water inside the bell JAR, which is coated with black cardboard, heats up more than the transparent one. In this way they&amp;#160;began to investigate climate change due to greenhouse gases.&amp;#160;&lt;/p&gt; &lt;p&gt;In the experiment, two bell glasses were used to represent the atmosphere layers. One was intermittently covered with pieces cut out of black cardboard. Black cardboard was used to represent the greenhouse gas due since the black colour absorbs light. Two beakers of the same size were used, filled with water. A thermometer was placed inside and bell jars were turned upside down and put over the beakers. The two thermometers were used to measure the water temperature inside the beakers.&amp;#160;&lt;/p&gt; &lt;p&gt;The first apparatus is the control group (inside uncovered). The second apparatus is the experimental group (covered with independent black cardboard). In the experimental and observation stage, the independent variable is the bell jar; the dependent variable is the water temperature. The constant variables are the size of the jar, the size of the beaker, the amount of water and the ambient conditions.&amp;#160;&lt;/p&gt; &lt;p&gt;Having set up the apparatus, the initial temperature of water was measured and recorded. Students carried out the experiment on a sunny day by placing the apparatus in a sun-covered field. They recorded the data in the tables they completed periodically. Then they shared the results with participants at the science festival.&amp;#160;&lt;/p&gt; &lt;p&gt;In this way they began to investigate the impact of greenhouse gases on climate change.&lt;/p&gt; &lt;/div&gt;

scholarly journals Indeks Kualitas Perairan dan Fitoplankton Periode Ramadan di Situ Gintung, Tangerang Selatan, Banten

2019 ◽  
Vol 3 (2) ◽  
pp. 105-121
Author(s):  
Yayan Mardiansyah Assuyuti ◽  
Alfan Farhan Rijaluddin ◽  
Firdaus Ramadhan
Keyword(s):  
Water Quality ◽  
Water Temperature ◽  
Correspondence Analysis ◽  
Water Quality Index ◽  
Quality Index ◽  
Pollution Indices ◽  
Lake Ecosystem ◽  
Muslim Community

The behavior of the Indonesian Muslim community has changed in the month of Ramadan and will affect the anthropogenic waste that enters the lake ecosystem. The study was conducted in Situ Gintung Lake, South Tangerang City, in the period before (BR), time (DR) and after (AR) Ramadan 2015. The aims of study was to determine (i) the chemical, physical and water quality using the water quality index (WQI), (ii) phytoplankton classification using codons, pollution and Saprobit indices and (iii) the correlation of chemical and physical of waters with phytoplankton. Water temperature, transparency, TDS and conductivity have significant differences (ANOVA, p < 0.05) in all periods except pH, DO and NPP (p > 0.05) with WQI was a medium to good categories. Classification of phytoplankton codons, algae and Saprobit pollution indices values ​​showed that Situ Gintung had meso to eutrophic categories and showed contamination in all periods, respectively. Canonical Correspondence Analysis (CCA) shows that phytoplankton correlate with BOD5.  

scholarly journals Environmental response to the cold climate event 8200 years ago as recorded at Højby Sø, Denmark

2008 ◽  
Vol 15 ◽  
pp. 57-60 ◽  
Author(s):  
Peter Rasmussen ◽  
Mikkel Ulfeldt Hede ◽  
Nanna Noe-Nygaard ◽  
Annemarie L. Clarke ◽  
Rolf D. Vinebrooke
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
North Atlantic ◽  
Ice Cores ◽  
Cold Climate ◽  
Future Climate Change ◽  
Lake Ecosystem ◽  
Climate Change Scenarios ◽  
The North ◽  
The North Atlantic

The need for accurate predictions of future environmental change under conditions of global warming has led to a great interest in the most pronounced climate change known from the Holocene: an abrupt cooling event around 8200 years before present (present = A.D. 1950), also known as the ‘8.2 ka cooling event’ (ka = kilo-annum = 1000 years). This event has been recorded as a negative δ18O excursion in the central Greenland ice cores (lasting 160 years with the lowest temperature at 8150 B.P.; Johnsen et al. 1992; Dansgaard 1993; Alley et al. 1997; Thomas et al. 2007) and in a variety of other palaeoclimatic archives including lake sediments, ocean cores, speleothems, tree rings, and glacier oscillations from most of the Northern Hemisphere (e.g. Alley & Ágústsdóttir 2005; Rohling & Pälike 2005). In Greenland the maximum cooling was estimated to be 6 ± 2°C (Alley et al. 1997) while in southern Fennoscandia and the Baltic countries pollenbased quantitative temperature reconstructions indicate a maximum annual mean temperature decrease of around 1.5°C (e.g. Seppä et al. 2007). Today there is a general consensus that the primary cause of the cooling event was the final collapse of the Laurentide ice sheet near Hudson Bay and the associated sudden drainage of the proglacial Lake Agassiz into the North Atlantic Ocean around 8400 B.P. (Fig. 1; Barber et al. 1999; Kleiven et al. 2008). This freshwater outflow, estimated to amount to c. 164,000 km3 of water, reduced the strength of the North Atlantic thermohaline circulation and thereby the heat transported to the North Atlantic region, resulting in an atmospheric cooling (Barber et al. 1999; Clark et al. 2001; Teller et al. 2002). The climatic consequences of this meltwater flood are assumed to be a good geological analogue for future climate-change scenarios, as a freshening of the North Atlantic is projected by almost all global-warming models (e.g. Wood et al. 2003; IPCC 2007) and is also currently being registered in the region (Curry et al. 2003). In an ongoing project, the influence of the 8.2 ka cooling event on a Danish terrestrial and lake ecosystem is being investigated using a variety of biological and geochemical proxy data from a sediment core extracted from Højby Sø, north-west Sjælland (Fig. 2). Here we present data on changes in lake hydrology and terrestrial vegetation in response to climate change, inferred from macrofossil data and pollen analysis, respectively.

scholarly journals Intraguild Predation Dynamics in a Lake Ecosystem Based on a Coupled Hydrodynamic-Ecological Model: The Example of Lake Kinneret (Israel)

Biology ◽  
2017 ◽  
Vol 6 (4) ◽  
pp. 22 ◽  
Author(s):  
Vardit Makler-Pick ◽  
Matthew R. Hipsey ◽  
Tamar Zohary ◽  
Yohay Carmel ◽  
Gideon Gal
Keyword(s):  
Intraguild Predation ◽  
Ecological Model ◽  
Lake Kinneret ◽  
Lake Ecosystem

Drop-In Tests of R-404A Alternative Refrigerants R-455A and R-454C in a Small Ice Maker

2019 ◽  
Vol 27 (02) ◽  
pp. 1950017
Author(s):  
Byungmoo Lee ◽  
Nae-Hyun Kim
Keyword(s):  
Global Warming ◽  
Water Temperature ◽  
Formation Time ◽  
Harsh Environment ◽  
Vapor Density ◽  
Alternative Refrigerants ◽  
Fin Tube ◽  
Ice Production ◽  
Tube Condenser

R-404A, which had long been used as the refrigerant of a unitary ice maker, has to be replaced due to global warming. In the present study, drop-in tests were conducted for long-term alternative refrigerants R-455A and R-454C on the ice maker of 100[Formula: see text]kg/day capacity. Five samples were made having different combinations of refrigerant, condenser and compressor. Tests were conducted changing the outdoor and the supply water temperature. At the standard outdoor condition (21∘C, 65 RH and 10∘C water temperature), change of refrigerant from R-404A to R-455A for the same ice maker extended the ice ball formation time by 13% and reduced the amount of ice production per day by 6%. Larger vapor density and smaller temperature glide of R-404A may have resulted in a better performance. Furthermore, adoption of a larger (from 1/3 HP to 3/8 HP) compressor reduced the ice ball formation time by 12% and increased the amount of ice production per day by 8%. In addition, change of the fin-tube condenser to the microchannel condenser reduced the ice ball formation time by 9% and increased the amount of ice production per day by 4%. The refrigerant charge was also significantly reduced from 440[Formula: see text]g to 316[Formula: see text]g. Thermal performance of R-454C was poorer than that of R-455A. Replacement to R-454C increased the ice ball formation time by 14% and decreased the amount of ice production per day by 8%. The reason may be attributed to a larger pressure lift, which leads to smaller refrigerant mass flow rate. Ice production was possible even at the harsh environment (35∘C, 65 RH and 21∘C water temperature), although the production amount decreased.

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