Lesson #3 Biogeochemical Cycles
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Limits of Iron Fertilization
LIMITS OF IRON FERTILIZATION Anand Gnanadesikan1, John P. Dunne1 and Irina Marinov2 1: NOAA Geophysical Fluid Dynamics Laboratory, PO Box 308, Princeton, NJ 08542 [email protected], [email protected] 2: Department of Earth, Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, [email protected] ABSTRACT Iron fertilization has been proposed as a cheap, controllable, and environmentally benign method for removing carbon dioxide from the atmosphere. While this is in fact the case in simple, 3-box models of the carbon cycle, more realistic models show that these claims fall short of reality. The fact that the efficiency of iron fertilization depends on the long term fate of the added iron and on the carbon associated with it makes tracking the effects of iron fertilization much more difficult and expensive than has been asserted. Additionally, advection of low nutrient water away from iron-rich areas can result in lowering production remotely, with potentially serious consequences. INTRODUCTION The idea of offsetting anthropogenic carbon dioxide emissions by fertilizing the ocean with iron has a number of superficially attractive features. A host of iron fertilization experiments have demonstrated that adding iron to surface waters leads to a local increase in productivity [see for example Coale et al., 1996]. Our own survey of the literature [Dunne et al. subm.] shows that this should be expected to lead to a local increase in particle export. It is claimed however, that this local increase in particle export would necessarily lead to an easily verifiable drawdown in atmospheric carbon dioxide. It is further claimed that the increase in export is controllable and environmentally benign, implying that the effects cease as soon as the fertilization stops. -
Modeling Biogeochemical Cycles
4 Modeling Biogeochemical Cycles Henning Rodhe 4.1 Introductory Remarks spatial average (i.e., the physical size of the reservoir itself) often has a horizontal size To formulate a model is to put together pieces of approaching that of a continent, or larger, i.e., knowledge about a particular system into a > 1000 km. The time scales corresponding to this consistent pattern that can form the basis for (1) spatial average are months, or longer. This interpretation of the past history of the system means that day-to-day variations in weather and (2) prediction of the future of the system. To and ocean currents are not generally considered be credible and useful, any model of a physical, explicitly when modeling biogeochemical cycles. chemical or biological system must rely on both The advent of fast computers and the avail- scientific fundamentals and observations of the ability of detailed data on the occurrence of world around us. High-quality observational certain chemical species have made it possible data are the basis upon which our understand- to construct meaningful cycle models with a ing of the environment rests. However, observa- much smaller and faster spatial and temporal tions themselves are not very useful unless the resolution. These spatial and time scales corre- results can be interpreted in some kind of model. spond to those in weather forecast models, i.e. Thus observations and modeling go hand in down to 100 km and 1 h. Transport processes hand. (e.g., for CO2 and sulfur compounds) in the This chapter focuses on types of models used oceans and atmosphere can be explicitly to describe the functioning of biogeochemical described in such models. -
An Iron Cycle Cascade Governs the Response of Equatorial Pacific Ecosystems to Climate Change
Received: 19 June 2020 | Revised: 7 August 2020 | Accepted: 9 August 2020 DOI: 10.1111/gcb.15316 PRIMARY RESEARCH ARTICLE An iron cycle cascade governs the response of equatorial Pacific ecosystems to climate change Alessandro Tagliabue1 | Nicolas Barrier2 | Hubert Du Pontavice3,4 | Lester Kwiatkowski5 | Olivier Aumont5 | Laurent Bopp6 | William W. L. Cheung4 | Didier Gascuel3 | Olivier Maury2 1School of Environmental Sciences, University of Liverpool, Liverpool, UK Abstract 2MARBEC (IRD, Univ. Montpellier, CNRS, Earth System Models project that global climate change will reduce ocean net pri- Ifremer), Sète, France mary production (NPP), upper trophic level biota biomass and potential fisheries 3ESE, Ecology and Ecosystem Health, Institut Agro, Rennes, France catches in the future, especially in the eastern equatorial Pacific. However, projec- 4Nippon Foundation-Nereus Program, tions from Earth System Models are undermined by poorly constrained assumptions Institute for the Oceans and Fisheries, regarding the biological cycling of iron, which is the main limiting resource for NPP University of British Columbia, Vancouver, BC, Canada over large parts of the ocean. In this study, we show that the climate change trends 5LOCEAN, Sorbonne Université-CNRS-IRD- in NPP and the biomass of upper trophic levels are strongly affected by modifying MNHN, Paris, France assumptions associated with phytoplankton iron uptake. Using a suite of model ex- 6ENS-LMD, Paris, France periments, we find 21st century climate change impacts on regional NPP range from Correspondence −12.3% to +2.4% under a high emissions climate change scenario. This wide range Alessandro Tagliabue, School of Environmental Sciences, University of arises from variations in the efficiency of iron retention in the upper ocean in the Liverpool, Liverpool, UK. -
Marine Microbiology: a Need for Deep-Sea In: Overbeck, J., Chrost, R
3. Role of Heterotrophic Bacteria in Marine Ecological Processes N. Ramaiah National Institute of Oceanography, Dona Paula, Goa 403 004, INDIA Introduction 30°C, salinity varying from below 10 to over 40 PSU, the existence, processes and physiology of life in this To the students of biology, the term bacterium elicits milieu are great challenges. smallness, abundance, invidiousness, and In almost every possible niche, the fundamental completeness of single celled prokaryotes. Among property of bacteria is growth/ multiplication. As a other characteristics, ubiquity, nutritional versatility, result of growth and activity, heterotrophic bacteria in infinite diversity and structural ‘simplicity’ come to one’s the marine sphere too are involved in a number of mind. This smallest autonomous biotic entity in the interrelated processes such as decomposition of living world is the most important functional unit. From complex molecules, respiration, mineralization, the knowledge perceivable through the copious and remineralization and, uptake of dissolved organic burgeoning literature on these tiny creatures, it compounds and their conversion to particulate matter. becomes a matter of great wonder that bacteria are Beginning the 1970s, there have been unprecedented so powerful and all-important in the functioning and discoveries related to marine microbial ecology. The µ stability of ecosystems. With less than 0.1 to 4 m in realization that ubiquitous and self-regulating microbial length, the abilities of decomposing innumerable communities provided the foundation to our organic molecules and several xenobiotics bring understanding on the processes in marine food-web heterotrophic bacteria to the centre-stage of nutrient (Landry, 2001). cycling within the earth’s ecosystems. -
Ecological Succession and Biogeochemical Cycles
Chapter 10: Changes in Ecosystems Lesson 10.1: Ecological Succession and Biogeochemical Cycles Can a plant really grow in hardened lava? It can if it is very hardy and tenacious. And that is how succession starts. It begins with a plant that must be able to grow on new land with minimal soil or nutrients. Lesson Objectives ● Outline primary and secondary succession, and define climax community. ● Define biogeochemical cycles. ● Describe the water cycle and its processes. ● Give an overview of the carbon cycle. ● Outline the steps of the nitrogen cycle. ● Understand the phosphorus cycle. ● Describe the ecological importance of the oxygen cycle. Vocabulary ● biogeochemical cycle ● groundwater ● primary succession ● carbon cycle ● nitrogen cycle ● runoff ● climax community ● nitrogen fixation ● secondary succession ● condensation ● phosphorus cycle ● sublimation ● ecological succession ● pioneer species ● transpiration ● evaporation ● precipitation ● water cycle Introduction Communities are not usually static. The numbers and types of species that live in them generally change over time. This is called ecological succession. Important cases of succession are primary and secondary succession. In Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical substance moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth. A cycle is a series of change which comes back to the starting point and which can be repeated. The term "biogeochemical" tells us that biological, geological and chemical factors are all involved. The circulation of chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water etc. through the biological and physical world are known as biogeochemical cycles. In effect, the element is recycled, although in some cycles there may be places (called reservoirs) where the element is accumulated or held for a long period of time (such as an ocean or lake for water). -
Iron Stable Isotopes Track Pelagic Iron Cycling During a Subtropical Phytoplankton Bloom
Iron stable isotopes track pelagic iron cycling during PNAS PLUS a subtropical phytoplankton bloom Michael J. Ellwooda,1, David A. Hutchinsb, Maeve C. Lohanc, Angela Milnec, Philipp Nasemannd, Scott D. Noddere, Sylvia G. Sanderd, Robert Strzepeka, Steven W. Wilhelmf, and Philip W. Boydg,2 aResearch School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia; bMarine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089; cSchool of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth PL4 8AA, United Kingdom; dMarine and Freshwater Chemistry, Department of Chemistry, University of Otago, Dunedin 9054, New Zealand; eNational Institute of Water and Atmospheric Research, Wellington 6021, New Zealand; fDepartment of Microbiology, The University of Tennessee, Knoxville, TN 37996; and gNational Institute of Water and Atmospheric Research Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin 9012, New Zealand Edited by Edward A. Boyle, Massachusetts Institute of Technology, Cambridge, MA, and approved December 1, 2014 (received for review November 11, 2014) The supply and bioavailability of dissolved iron sets the magnitude (www.geotraces.org) process voyages (2008 and 2012) designed of surface productivity for ∼40% of the global ocean. The redox to study temporal changes in the biogeochemical cycling of Fe at state, organic complexation, and phase (dissolved versus particu- the same locality in subtropical waters (38°S−39°S, 178°W late) of iron are key determinants of iron bioavailability in the −180°W) within the mesoscale eddy field east of New Zealand marine realm, although the mechanisms facilitating exchange be- (3). -
Microbial Iron Metabolism in Natural Environments Marianne Erbs & Jim Spain
L I Microbial iron metabolism in natural environments Marianne Erbs & Jim Spain Microbial Diversity 2002 Microbial iron metabolism in natural environments Marianne Erbs & Jim Spain [email protected] [email protected] Abstract The aim of this project was to assess the diversity of iron metabolizing bacteria in several ecological niches by culture-dependent and culture-independent methods. In particular, we wanted to determine whether non-phototrophic, anaerobic nitrate-dependent Fe(II)-oxidizers coexist with aerobic Fe(1I)-oxidizers and facultatively anaerobic Fe(III)-reducers in natural habitats. To this end, we sampled iron-rich sites in freshwater, estuarine and marine environments and enriched for non-phototrophic anaerobic and aerobic Fe(II)-oxidizers. The identification of the two environmentally most important facultatively anaerobic Fe(III) reducers and one aerobic heterotrophic Fe(II)-oxidizer in the sediment samples was carried out by means of fluorescent in situ hybridization (FISH). We were able to culture aerobic Fe(II) oxidizers in gradient tubes from each sample site. Nitrate-reducing Fe(TI)-oxidizers were only found in sediments from a Cranberry Bog. Geobacter, S’hewanella and Leptothrix coexist in Salt Pond at the oxic/anoxic interface. Microbial iron metabolism in natural environments Marianne Erbs & Jim Spain Introduction The significance of bacteria in the biogeochemical cycling of iron has been broadly recognized over the past two decades. In Fig. 1 the role of dissimilatory anaerobic Fe(III)-reducers as well as acidophilic and neutrophilic aerobic Fe(II)-oxidizers, anaerobic phototrophic Fe(II)-oxidizers and facultatively anaerobic nitrate-reducing Fe(11)-oxidizers in the microbial cycling of iron is shown. -
DOE Mission: Carbon Cycling and Sequestration
APPENDIX C Appendix C. DOE Mission: Carbon Cycling and Sequestration C.1.1. The Climate Change Challenge ..............................................................................................................................228 C.1.2. The Role of Microbes ..................................................................................................................................................229 C.1.3. Microbial Ocean Communities ................................................................................................................................231 C.1.3.1. Photosynthetic Capabilities .......................................................................................................................................231 C.1.3.2. Strategies for Increasing Ocean CO2 Pools ................................................................................................................231 C.1.3.3. GTL’s Vision for Ocean Systems .................................................................................................................................233 C.1.3.3.1. Gaps in Scientific Understanding .............................................................................................................................233 C.1.3.3.2. Scientific and Technological Capabilities Required ..................................................................................................233 C.1.4. Terrestrial Microbial Communities ........................................................................................................................235 -
Unit 2 Ecosystems Definition and Concept of Ecosystem Fig. Pond
Subject- Environmental Studies Unit 2 Ecosystems Definition and concept of Ecosystem In nature several communities of organisms live together and interact with each other as well as with their physical environment as an ecological unit. We call it an ecosystem. The term ‘ecosystem’ was coined by A.G. Tansley in 1935. An ecosystem is a functional unit of nature encompassing complex interaction between its biotic (living) and abiotic (non- living) components. For example- a pond is a good example of ecosystem, shown below. Fig. Pond Ecosystem Structure of ecosystem (biotic and abiotic components) Functions of ecosystem Ecosystems are complex dynamic system. They perform certain functions. These are:- (i) Energy flow through food chain (ii) Nutrient cycling (biogeochemical cycles) (iii) Ecological succession or ecosystem development (iv) Homeostasis (or cybernetic) or feedback control mechanisms Food Chain Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten is called a food chain. Grasses → Grasshopper → Frog → Snake → Hawk/Eagle Each step in the food chain is called trophic level. In the above example grasses are 1st, and eagle represents the 5th trophic level. During this process of transfer of energy some energy (90 per cent) is lost into the system as heat energy and is not available to the next trophic level. Therefore, the number of steps are limited in a chain to 4 or 5. Autotrophs: They are the producers of food for all other organisms of the ecosystem. They are largely green plants and convert inorganic material in the presence of solar energy by the process of photosynthesis into the chemical energy (food). -
Biogeochemical Cycles and Climate Change
White Paper on WCRP Grand Challenge – Draft, February 29, 2016 Biogeochemical Cycles and Climate Change Co-chairs*: Tatiana Ilyina1 and Pierre Friedlingstein2 Processes governing natural biogeochemical cycles and feedbacks currently remove anthropogenic carbon dioxide from the atmosphere, helping to limit climate change. These mitigating effects may significantly reduce in a warmer climate, amplifying risk of climate change and impacts. How the biogeochemical cycles and feedbacks will change is very uncertain. Our grand challenge is to understand how these biogeochemical cycles and feedbacks control greenhouse gas concentrations and impact on the climate system. This Grand Challenge will be addressed through community-led research initiatives on the following key guiding questions: • Q1: What are the drivers of land and ocean carbon sinks? • Q2: What is the potential for amplification of climate change over the 21st century via climate-biogeochemical feedbacks? • Q3: How do greenhouse gases fluxes from highly vulnerable carbon reservoirs respond to changing climate (including climate extremes and abrupt changes)? 1. Background The land and ocean biogeochemical cycles are key components of the Earth’s climate system. The surface fluxes of many greenhouse gases and aerosol precursors are controlled by biogeochemical and physical processes and are sensitive to changes in climate and atmospheric composition. Most importantly, biogeochemical processes control atmospheric concentrations of the main greenhouse gases (CO2, CH4 and N2O). Plants, soils and permafrost on the land together contain at least five times as much carbon as the atmosphere, and the global ocean contains at least fifty times more carbon than the atmosphere. Based on the 2015 Global Carbon Budget estimates, since 1870, CO2 emissions from fossil fuel combustion have released about 400±20 GtC (Gigatonnes carbon) to the atmosphere, while land use change is estimated to have released an additional 145±50 GtC. -
An Analysis of Phosphorus Loading and Trophic State in Fletchers Lake, Nova Scotia
An Analysis of Phosphorus Loading and Trophic State in Fletchers Lake, Nova Scotia by Joanna Poltarowicz Submitted in partial fulfilment of the requirements for the degree of Master of Applied Science at Dalhousie University Halifax, Nova Scotia March 2017 © Copyright by Joanna Poltarowicz, 2017 “It always seems impossible until it’s done.” - Nelson Mandela ii TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................................... v LIST OF TABLES ...................................................................................................................... vii ABSTRACT .................................................................................................................................. ix LIST OF ABBREVIATIONS AND SYMBOLS USED .............................................................. x ACKNOWLEDGEMENTS ........................................................................................................ xii Chapter 1 Introduction ........................................................................................................ 1 1.1 Phosphorus and Eutrophication ........................................................................................ 1 1.2 Motivation for Research ........................................................................................................ 1 1.2.1 Research Objectives ...................................................................................................................... -
Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions
Article Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions Guilin Han 1,* , Anton Eisenhauer 2, Jie Zeng 1 and Man Liu 1 1 Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China; [email protected] (J.Z.); [email protected] (M.L.) 2 GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany; [email protected] * Correspondence: [email protected]; Tel.: +86-10-82-323-536 Abstract: In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ44/40Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ44/40Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ44/40Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ44/40Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant 40 Citation: Han, G.; Eisenhauer, A.; in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope ( Ca) is Zeng, J.; Liu, M.