Energy Flow through Ecosystems

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Energy Flow through Ecosystems Energy Flow through Ecosystems Bởi: OpenStaxCollege An ecosystem is a community of living organisms and their abiotic (non-living) environment Ecosystems can be small, such as the tide pools found near the rocky shores of many oceans, or large, such as those found in the tropical rainforest of the Amazon in Brazil ([link]) A (a) tidal pool ecosystem in Matinicus Island, Maine, is a small ecosystem, while the (b) Amazon rainforest in Brazil is a large ecosystem (credit a: modification of work by Jim Kuhn; credit b: modification of work by Ivan Mlinaric) There are three broad categories of ecosystems based on their general environment: freshwater, marine, and terrestrial Within these three categories are individual ecosystem types based on the environmental habitat and organisms present Ecology of Ecosystems Life in an ecosystem often involves competition for limited resources, which occurs both within a single species and between different species Organisms compete for food, water, sunlight, space, and mineral nutrients These resources provide the energy for metabolic processes and the matter to make up organisms’ physical structures Other critical factors influencing community dynamics are the components of its physical 1/11 Energy Flow through Ecosystems environment: a habitat’s climate (seasons, sunlight, and rainfall), elevation, and geology These can all be important environmental variables that determine which organisms can exist within a particular area Freshwater ecosystems are the least common, occurring on only 1.8 percent of Earth's surface These systems comprise lakes, rivers, streams, and springs; they are quite diverse, and support a variety of animals, plants, fungi, protists and prokaryotes Marine ecosystems are the most common, comprising 75 percent of Earth's surface and consisting of three basic types: shallow ocean, deep ocean water, and deep ocean bottom Shallow ocean ecosystems include extremely biodiverse coral reef ecosystems, yet the deep ocean water is known for large numbers of plankton and krill (small crustaceans) that support it These two environments are especially important to aerobic respirators worldwide, as the phytoplankton perform 40 percent of all photosynthesis on Earth Although not as diverse as the other two, deep ocean bottom ecosystems contain a wide variety of marine organisms Such ecosystems exist even at depths where light is unable to penetrate through the water Terrestrial ecosystems, also known for their diversity, are grouped into large categories called biomes A biome is a large-scale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions Examples of biomes include tropical rainforests, savannas, deserts, grasslands, temperate forests, and tundras Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them For example, the saguaro cacti (Carnegiea gigantean) and other plant life in the Sonoran Desert, in the United States, are relatively diverse compared with the desolate rocky desert of Boa Vista, an island off the coast of Western Africa ([link]) Desert ecosystems, like all ecosystems, can vary greatly The desert in (a) Saguaro National Park, Arizona, has abundant plant life, while the rocky desert of (b) Boa Vista island, Cape Verde, Africa, is devoid of plant life (credit a: modification of work by Jay Galvin; credit b: modification of work by Ingo Wölbern) 2/11 Energy Flow through Ecosystems Ecosystems and Disturbance Ecosystems are complex with many interacting parts They are routinely exposed to various disturbances: changes in the environment that affect their compositions, such as yearly variations in rainfall and temperature Many disturbances are a result of natural processes For example, when lightning causes a forest fire and destroys part of a forest ecosystem, the ground is eventually populated with grasses, followed by bushes and shrubs, and later mature trees: thus, the forest is restored to its former state This process is so universal that ecologists have given it a name—succession The impact of environmental disturbances caused by human activities is now as significant as the changes wrought by natural processes Human agricultural practices, air pollution, acid rain, global deforestation, overfishing, oil spills, and illegal dumping on land and into the ocean all have impacts on ecosystems Equilibrium is a dynamic state of an ecosystem in which, despite changes in species numbers and occurrence, biodiversity remains somewhat constant In ecology, two parameters are used to measure changes in ecosystems: resistance and resilience The ability of an ecosystem to remain at equilibrium in spite of disturbances is called resistance The speed at which an ecosystem recovers equilibrium after being disturbed is called resilience Ecosystem resistance ...Sensors 2012, 12, 3562-3577; doi:10.3390/s120303562 sensors ISSN 1424-8220 www.mdpi.com/journal/sensors Article Electrochemical Oxidation of Cysteine at a Film Gold Modified Carbon Fiber Microelectrode Its Application in a Flow—Through Voltammetric Sensor Lai-Hao Wang * and Wen-Shiuan Huang Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, 60 Erh-Jen Road, Section 1, Jen Te, Tainan 71743, Taiwan; E-Mail: michellehuang@ritdisplay.com * Author to whom correspondence should be addressed; E-Mail: e201466.wang@msa.hinet.net; Tel.: +886-6-266-4911; Fax: +886-6-266-7319. Received: 22 February 2012; in revised form: 6 March 2012 / Accepted: 12 March 2012 / Published: 14 March 2012 Abstract: A flow-electrolytical cell containing a strand of micro Au modified carbon fiber electrodes (CFE) has been designedand characterized for use in a voltammatric detector for detecting cysteine using high-performance liquid chromatography. Cysteine is more efficiently electrochemical oxidized on a Au /CFE than a bare gold and carbon fiber electrode. The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents. For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L −1 was found. The limit of quantification for cysteine was below 60 ng·mL −1 . Keywords: micro Au-modified carbon fiber electrode; pulse amperometric detection; cysteine 1. Introduction The sulfhydryl (-SH) group of cysteine plays a key role in the biological activity of proteins and enzymes. It is responsible for disulfide bridges in peptides and proteins. L-Cysteine (Cys, l-2-amino-3-mercaptopropionic acid) is a biologically important sulfur-containing amino acid which is involved in a variety of important cellular functions, including protein synthesis, detoxification and metabolism [1]. The biological reactions of cysteine are accompanied by SH-SS exchange reactions OPEN ACCESS Sensors 2012, 12 3563 and the conversion of the disulphide into a dithiol group [2]. Thioproline (thiazolidine 4-carboxylic acid) is metabolized in vitro by liver mitochondria to produce the ring-opened N-formylcysteine; a reaction reported to be catalysed by a specific dehydrogenase described the in vivo conversion of thioproline to cysteine, the reaction presumably occurring via N-formylcysteine [3]. Since cysteine itself lacks a strong chromophore, determining its presence/concentration by absorbance measurements is very difficult. Spectrophotometric detection is based on derivatization with cromogenic reagents in order to allow its detection by absorption spectrometry [4]. Many electrochemical strategies have been reported including chemically modified graphite electrodes [2,5–7] such as with cobalt (II) cyclohexylbutyate, praseodymium hexacyanoferrate, and Co(II)-Y zeolite modified graphite electrode; and using Nile blue A as a mediator at a glassy carbon electrode for determination of L-cysteine; Hg thin film sensor [8], biosensors based on electrodes modified with enzymes such as tyrosinase, laccase, L-cysteine desulfhydrase [9–11]. On the basis of the presence of the sulphuryl (-SH) function group in the structure of cysteine, its voltammetric adsorption and desorption has been investigated at a bare gold [...]... far-seeing people who have spent a lifetime exploring, teaching, and writing about energy efficiency and renewable energy Their names, and the names of their organizations, too numerous to list here, grace the pages of the resource guide at the end of the book Without them, this book never could have been possible Without them, renewable energy would still be a wishful dream So a world of thanks to. .. us 12 the homeowner’s guide to renewable energy with additional natural gas Their reserves are on the decline and their climate is colder than ours It’s doubtful that they will expand production to supply their energy- hungry neighbor to the south Canada has its own future to protect Can we stave off the imminent decline in natural gas by tapping into natural gas deposits elsewhere? 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Fully formatted PDF and full text (HTML) versions will be made available soon. Improving energy efficiency through multimode transmission in the downlink MIMO systems EURASIP Journal on Wireless Communications and Networking 2011, 2011:200 doi:10.1186/1687-1499-2011-200 Jie Xu (suming@mail.ustc.edu.cn) Ling Qiu (lqiu@ustc.edu.cn) Chengwen Yu (chengwen.yu@huawei.com) ISSN 1687-1499 Article type Research Submission date 22 February 2011 Acceptance date 9 December 2011 Publication date 9 December 2011 Article URL http://jwcn.eurasipjournals.com/content/2011/1/200 This peer-reviewed article was published immediately upon acceptance. It can be downloaded, printed and distributed freely for any purposes (see copyright notice below). For information about publishing your research in EURASIP WCN go to http://jwcn.eurasipjournals.com/authors/instructions/ For information about other SpringerOpen publications go to http://www.springeropen.com EURASIP Journal on Wireless Communications and Networking © 2011 Xu et al. ; licensee Springer. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 Improving energy efficiency through multimode transmission in the downlink MIMO systems Jie Xu 1 , Ling Qiu ∗1 and Chengwen Yu 2 1 Personal Communication Network & Spread Spectrum Laboratory (PCN&SS), University of Science and Technology of China (USTC), Hefei, 230027 Anhui, China 2 Wireless research, Huawei Technologies Co. Ltd., Shanghai, China ∗ Corresponding author: lqiu@ustc.edu.cn Email addresses: JX: suming@mail.ustc.edu.cn CY: chengwen.yu@huawei.com Abstract Adaptively adjusting system parameters including bandwidth, transmit power and mode to maximize the “Bits per-Joule” energy efficiency (BPJ-EE) in the downlink MIMO systems with imperfect channel state information at the transmitter (CSIT) is considered in this article. By mode, we refer to choice of transmission schemes i.e., singular value decomposition (SVD) or block diagonalization (BD), active transmit/receive antenna number and active user number. We derive optimal bandwidth and transmit power for each dedicated mode at first, in which accurate capacity estimation strategies are proposed to cope with the imperfect CSIT caused capacity prediction problem. Then, an ergodic capacity-based mode switching strategy is proposed to further improve the BPJ-EE, which provides insights into the preferred mode under given scenarios. Mode switching compromises different power parts, exploits the trade- off between the multiplexing gain and the imperfect CSIT caused inter-user interference and improves the BPJ-EE 2 significantly. Keywords: Bits per-Joule energy efficiency (BPJ-EE); downlink MIMO systems; singular value decomposition (SVD); block diagonalization (BD); imperfect CSIT. 1. Introduction Energy efficiency is becoming increasingly important for the future radio access networks due to the climate change and the operator’s increasing operational cost. As base stations (BSs) take the main parts of the energy consumption [1, 2], improving the energy efficiency of BS is significant. Additionally, multiple-input multiple-output (MIMO) has become the key technology in the next generation broadband wireless networks such as WiMAX and 3GPP-LTE. Therefore, we will focus on the maximizing energy efficiency ENERGY FLOW IN ECOSYSTEMS • All organisms require energy: for growth, maintenance, reproduction, locomotion, etc • Hence, for all organisms there must be:  A source of energy  A loss of usable energy Types of energy heat energy mechanical energy (+gravitational energy, etc.) chemical energy = energy stored in molecular bonds The distribution of sola radiation energy in the biosphere 0.8% 0.2% Heating air, land, ocean Evaporation 30.0% 46.0% Reflection Photosynthesis 23.0% Wave, wind This pattern of energy flow among different organisms is the TROPHIC STRUCTURE of an ecosystem Transformations of energy The transformations of energy from solar radiation to chemical energy and mechanical energy and finally back to heat of Ecosystem Ecology Energy and biomass pyramids The concepts • PG: Gross primary productivity – = the total rate of photosynthesis – = the rate of energy capture by producers (kcal/m2/yr) – = the amount of new biomass of producers (g/m2/yr) • PN = PG – R; Net primary production is thus the amount of energy stored by the producers and potentially available to consumers and decomposers • B: Standing crop Biomass – the amount of accumulated organic matter found in an area at a given time The concepts • NU: Not consumed • NA: Undigested / Fecal wastes • R: Respiration • P: Secondary productivity – the rate of production of new biomass by consumers, – the rate at which consumers convert organic material into new biomass of consumers The common method of measuring PN  Terrestrial ecosystems  To estimate the change in Standing crop Biomass over a given time interval (t2 –t1)  B = B(t2) – B(t1)  PN = B + D + C  D: loss of biomass due to the dead of plants from t1 to t2  C: loss of biomass due to consumption by consumer Primary production varies with time Net primary production (NPP) and standing biomass allocation for a 90-year-old Michigan forest estimated from inventory-based methods in which biomass growth is quantified over time (Gough et al 2008) Primary productivity limits secondary production Net primary productivity (kJ/m2/yr) Primary productivity limits secondary production  Trophic efficency (TE): the ratio of productivity in a given trophic levelGrowth (Pn) to trophic level it feeds on (Pn-1Respiration ) 33J Undigested 100J 67J (P) TE = Pn / Pn-1  Growth efficency: the ratio of energy for growth to total energy 200J (A) Growth efficency (P/A) = 33/200 = 16,5% Production efficiency (x100) of various animal group (Humphrey, 1979) Group P/A (%) Group P/A (%) Mice 4.10 Orthoptera 41.67 Voles 2.63 Hemiptera 41.90 Other mammals 2.92 All other insects 41.23 Birds 1.26 Mollusca 21.59 Fish 9.74 Crustacea 24.96 8.31 All other noninsect invertebrates 27.68 Social insects General patterns of energy flow through ecosystems (Begon et al, 1986) FOREST Respiration Respiration GRAZER SYSTEM DECOMPOSER SYSTEM NET PRIMARY PRODUCTIVITY DEAD ORGANIC MATTER General patterns of energy flow through ecosystems (Begon et al, 1986) GRASSLAND Respiration Respiration GRAZER SYSTEM DECOMPOSER SYSTEM NET PRIMARY PRODUCTIVITY DEAD ORGANIC MATTER General patterns of energy flow through ecosystems (Begon et al, 1986) PHYTOPLANKTON COMMUNITY Respiration Respiration GRAZER SYSTEM DECOMPOSER SYSTEM NET PRIMARY PRODUCTIVITY DEAD ORGANIC MATTER General patterns of energy flow through ecosystems (Begon et al, 1986) STREAM COMMUNITY Respiration Respiration GRAZER SYSTEM DECOMPOSER SYSTEM NET PRIMARY PRODUCTIVITY DEAD ORGANIC MATTER From terrestrial catchment The net primary productivity of biomes Estuaries Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland ... by Jay Galvin; credit b: modification of work by Ingo Wölbern) 2/11 Energy Flow through Ecosystems Ecosystems and Disturbance Ecosystems are complex with many interacting parts They are routinely... this food chain 3/11 Energy Flow through Ecosystems These are the trophic levels of a food chain in Lake Ontario at the United States–Canada border Energy and nutrients flow from photosynthetic... the amount of energy remaining in the food chain may not be great enough to support viable populations at yet a higher trophic level 4/11 Energy Flow through Ecosystems The relative energy in trophic