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28.2: Biogeochemical Cycles - Biology

28.2: Biogeochemical Cycles - Biology


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Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during the transfers between trophic levels. Rather than flowing through an ecosystem, the matter that makes up living organisms is conserved and recycled. The six most common elements associated with organic molecules—carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur—take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath Earth’s surface. Geologic processes, such as weathering, erosion, water drainage, and the subduction of the continental plates, all play a role in the cycling of elements on Earth. Because geology and chemistry have major roles in the study of this process, the recycling of inorganic matter between living organisms and their nonliving environment is called a biogeochemical cycle.

Water, which contains hydrogen and oxygen, is essential to all living processes. The hydrosphere is the area of Earth where water movement and storage occurs: as liquid water on the surface (rivers, lakes, oceans) and beneath the surface (groundwater) or ice, (polar ice caps and glaciers), and as water vapor in the atmosphere. Carbon is found in all organic macromolecules and is an important constituent of fossil fuels. Nitrogen is a major component of our nucleic acids and proteins and is critical to human agriculture. Phosphorus, a major component of nucleic acids, is one of the main ingredients (along with nitrogen) in artificial fertilizers used in agriculture, which has environmental impacts on our surface water. Sulfur, critical to the three-dimensional folding of proteins (as in disulfide binding), is released into the atmosphere by the burning of fossil fuels.

The cycling of these elements is interconnected. For example, the movement of water is critical for the leaching of nitrogen and phosphate into rivers, lakes, and oceans. The ocean is also a major reservoir for carbon. Thus, mineral nutrients are cycled, either rapidly or slowly, through the entire biosphere between the biotic and abiotic world and from one living organism to another.

CONCEPT IN ACTION

Head to this website to learn more about biogeochemical cycles.

The Water Cycle

Water is essential for all living processes. The human body is more than one-half water and human cells are more than 70 percent water. Thus, most land animals need a supply of fresh water to survive. Of the stores of water on Earth, 97.5 percent is salt water (Figure 20.2.1). Of the remaining water, 99 percent is locked as underground water or ice. Thus, less than one percent of fresh water is present in lakes and rivers. Many living things are dependent on this small amount of surface fresh water supply, a lack of which can have important effects on ecosystem dynamics. Humans, of course, have developed technologies to increase water availability, such as digging wells to harvest groundwater, storing rainwater, and using desalination to obtain drinkable water from the ocean. Although this pursuit of drinkable water has been ongoing throughout human history, the supply of fresh water continues to be a major issue in modern times.

The various processes that occur during the cycling of water are illustrated in Figure 20.2.2. The processes include the following:

  • evaporation and sublimation
  • condensation and precipitation
  • subsurface water flow
  • surface runoff and snowmelt
  • streamflow

The water cycle is driven by the Sun’s energy as it warms the oceans and other surface waters. This leads to evaporation (water to water vapor) of liquid surface water and sublimation (ice to water vapor) of frozen water, thus moving large amounts of water into the atmosphere as water vapor. Over time, this water vapor condenses into clouds as liquid or frozen droplets and eventually leads to precipitation (rain or snow), which returns water to Earth’s surface. Rain reaching Earth’s surface may evaporate again, flow over the surface, or percolate into the ground. Most easily observed is surface runoff: the flow of fresh water either from rain or melting ice. Runoff can make its way through streams and lakes to the oceans or flow directly to the oceans themselves.

In most natural terrestrial environments rain encounters vegetation before it reaches the soil surface. A significant percentage of water evaporates immediately from the surfaces of plants. What is left reaches the soil and begins to move down. Surface runoff will occur only if the soil becomes saturated with water in a heavy rainfall. Most water in the soil will be taken up by plant roots. The plant will use some of this water for its own metabolism, and some of that will find its way into animals that eat the plants, but much of it will be lost back to the atmosphere through a process known as evapotranspiration. Water enters the vascular system of the plant through the roots and evaporates, or transpires, through the stomata of the leaves. Water in the soil that is not taken up by a plant and that does not evaporate is able to percolate into the subsoil and bedrock. Here it forms groundwater.

Groundwater is a significant reservoir of fresh water. It exists in the pores between particles in sand and gravel, or in the fissures in rocks. Shallow groundwater flows slowly through these pores and fissures and eventually finds its way to a stream or lake where it becomes a part of the surface water again. Streams do not flow because they are replenished from rainwater directly; they flow because there is a constant inflow from groundwater below. Some groundwater is found very deep in the bedrock and can persist there for millennia. Most groundwater reservoirs, or aquifers, are the source of drinking or irrigation water drawn up through wells. In many cases these aquifers are being depleted faster than they are being replenished by water percolating down from above.

Rain and surface runoff are major ways in which minerals, including carbon, nitrogen, phosphorus, and sulfur, are cycled from land to water. The environmental effects of runoff will be discussed later as these cycles are described.

The Carbon Cycle

Carbon is the fourth most abundant element in living organisms. Carbon is present in all organic molecules, and its role in the structure of macromolecules is of primary importance to living organisms. Carbon compounds contain energy, and many of these compounds from plants and algae have remained stored as fossilized carbon, which humans use as fuel. Since the 1800s, the use of fossil fuels has accelerated. As global demand for Earth’s limited fossil fuel supplies has risen since the beginning of the Industrial Revolution, the amount of carbon dioxide in our atmosphere has increased as the fuels are burned. This increase in carbon dioxide has been associated with climate change and is a major environmental concern worldwide.

The carbon cycle is most easily studied as two interconnected subcycles: one dealing with rapid carbon exchange among living organisms and the other dealing with the long-term cycling of carbon through geologic processes. The entire carbon cycle is shown in Figure 20.2.3.

The Biological Carbon Cycle

Living organisms are connected in many ways, even between ecosystems. A good example of this connection is the exchange of carbon between heterotrophs and autotrophs within and between ecosystems by way of atmospheric carbon dioxide. Carbon dioxide is the basic building block that autotrophs use to build multi-carbon, high-energy compounds, such as glucose. The energy harnessed from the Sun is used by these organisms to form the covalent bonds that link carbon atoms together. These chemical bonds store this energy for later use in the process of respiration. Most terrestrial autotrophs obtain their carbon dioxide directly from the atmosphere, while marine autotrophs acquire it in the dissolved form (carbonic acid, HCO3). However the carbon dioxide is acquired, a byproduct of fixing carbon in organic compounds is oxygen. Photosynthetic organisms are responsible for maintaining approximately 21 percent of the oxygen content of the atmosphere that we observe today.

The partners in biological carbon exchange are the heterotrophs (especially the primary consumers, largely herbivores). Heterotrophs acquire the high-energy carbon compounds from the autotrophs by consuming them and breaking them down by respiration to obtain cellular energy, such as ATP. The most efficient type of respiration, aerobic respiration, requires oxygen obtained from the atmosphere or dissolved in water. Thus, there is a constant exchange of oxygen and carbon dioxide between the autotrophs (which need the carbon) and the heterotrophs (which need the oxygen). Autotrophs also respire and consume the organic molecules they form: using oxygen and releasing carbon dioxide. They release more oxygen gas as a waste product of photosynthesis than they use for their own respiration; therefore, there is excess available for the respiration of other aerobic organisms. Gas exchange through the atmosphere and water is one way that the carbon cycle connects all living organisms on Earth.

The Biogeochemical Carbon Cycle

The movement of carbon through land, water, and air is complex, and, in many cases, it occurs much more slowly geologically than the movement between living organisms. Carbon is stored for long periods in what are known as carbon reservoirs, which include the atmosphere, bodies of liquid water (mostly oceans), ocean sediment, soil, rocks (including fossil fuels), and Earth’s interior.

As stated, the atmosphere is a major reservoir of carbon in the form of carbon dioxide that is essential to the process of photosynthesis. The level of carbon dioxide in the atmosphere is greatly influenced by the reservoir of carbon in the oceans. The exchange of carbon between the atmosphere and water reservoirs influences how much carbon is found in each, and each one affects the other reciprocally. Carbon dioxide (CO2) from the atmosphere dissolves in water and, unlike oxygen and nitrogen gas, reacts with water molecules to form ionic compounds. Some of these ions combine with calcium ions in the seawater to form calcium carbonate (CaCO3), a major component of the shells of marine organisms. These organisms eventually form sediments on the ocean floor. Over geologic time, the calcium carbonate forms limestone, which comprises the largest carbon reservoir on Earth.

On land, carbon is stored in soil as organic carbon as a result of the decomposition of living organisms or from weathering of terrestrial rock and minerals. Deeper under the ground, at land and at sea, are fossil fuels, the anaerobically decomposed remains of plants that take millions of years to form. Fossil fuels are considered a non-renewable resource because their use far exceeds their rate of formation. A non-renewable resource is either regenerated very slowly or not at all. Another way for carbon to enter the atmosphere is from land (including land beneath the surface of the ocean) by the eruption of volcanoes and other geothermal systems. Carbon sediments from the ocean floor are taken deep within Earth by the process of subduction: the movement of one tectonic plate beneath another. Carbon is released as carbon dioxide when a volcano erupts or from volcanic hydrothermal vents.

Carbon dioxide is also added to the atmosphere by the animal husbandry practices of humans. The large number of land animals raised to feed Earth’s growing human population results in increased carbon-dioxide levels in the atmosphere caused by their respiration. This is another example of how human activity indirectly affects biogeochemical cycles in a significant way. Although much of the debate about the future effects of increasing atmospheric carbon on climate change focuses on fossils fuels, scientists take natural processes, such as volcanoes, plant growth, soil carbon levels, and respiration, into account as they model and predict the future impact of this increase.

The Nitrogen Cycle

Getting nitrogen into the living world is difficult. Plants and phytoplankton are not equipped to incorporate nitrogen from the atmosphere (which exists as tightly bonded, triple covalent N2) even though this molecule comprises approximately 78 percent of the atmosphere. Nitrogen enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2). Cyanobacteria live in most aquatic ecosystems where sunlight is present; they play a key role in nitrogen fixation. Cyanobacteria are able to use inorganic sources of nitrogen to “fix” nitrogen. Rhizobium bacteria live symbiotically in the root nodules of legumes (such as peas, beans, and peanuts) and provide them with the organic nitrogen they need. Free-living bacteria, such as Azotobacter, are also important nitrogen fixers.

Organic nitrogen is especially important to the study of ecosystem dynamics since many ecosystem processes, such as primary production and decomposition, are limited by the available supply of nitrogen. As shown in Figure 20.2.4, the nitrogen that enters living systems by nitrogen fixation is eventually converted from organic nitrogen back into nitrogen gas by bacteria. This process occurs in three steps in terrestrial systems: ammonification, nitrification, and denitrification. First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals into ammonium (NH4+ ) by certain bacteria and fungi. Second, this ammonium is then converted to nitrites (NO2) by nitrifying bacteria, such as Nitrosomonas, through nitrification. Subsequently, nitrites are converted to nitrates (NO3) by similar organisms. Lastly, the process of denitrification occurs, whereby bacteria, such as Pseudomonas and Clostridium, convert the nitrates into nitrogen gas, thus allowing it to re-enter the atmosphere.

ART CONNECTION

Which of the following statements about the nitrogen cycle is false?

  1. Ammonification converts organic nitrogenous matter from living organisms into ammonium (NH4+).
  2. Denitrification by bacteria converts nitrates (NO3)to nitrogen gas (N2).
  3. Nitrification by bacteria converts nitrates (NO3)to nitrites (NO2)
  4. Nitrogen fixing bacteria convert nitrogen gas (N2) into organic compounds.

Human activity can release nitrogen into the environment by two primary means: the combustion of fossil fuels, which releases different nitrogen oxides, and by the use of artificial fertilizers (which contain nitrogen and phosphorus compounds) in agriculture, which are then washed into lakes, streams, and rivers by surface runoff. Atmospheric nitrogen (other than N2) is associated with several effects on Earth’s ecosystems including the production of acid rain (as nitric acid, HNO3) and greenhouse gas effects (as nitrous oxide, N2O), potentially causing climate change. A major effect from fertilizer runoff is saltwater and freshwater eutrophication, a process whereby nutrient runoff causes the overgrowth of algae and a number of consequential problems.

A similar process occurs in the marine nitrogen cycle, where the ammonification, nitrification, and denitrification processes are performed by marine bacteria and archaea. Some of this nitrogen falls to the ocean floor as sediment, which can then be moved to land in geologic time by uplift of Earth’s surface, and thereby incorporated into terrestrial rock. Although the movement of nitrogen from rock directly into living systems has been traditionally seen as insignificant compared with nitrogen fixed from the atmosphere, a recent study showed that this process may indeed be significant and should be included in any study of the global nitrogen cycle.1

The Phosphorus Cycle

Phosphorus is an essential nutrient for living processes; it is a major component of nucleic acids and phospholipids, and, as calcium phosphate, makes up the supportive components of our bones. Phosphorus is often the limiting nutrient (necessary for growth) in aquatic, particularly freshwater, ecosystems.

Phosphorus occurs in nature as the phosphate ion (PO43-). In addition to phosphate runoff as a result of human activity, natural surface runoff occurs when it is leached from phosphate-containing rock by weathering, thus sending phosphates into rivers, lakes, and the ocean. This rock has its origins in the ocean. Phosphate-containing ocean sediments form primarily from the bodies of ocean organisms and from their excretions. However, volcanic ash, aerosols, and mineral dust may also be significant phosphate sources. This sediment then is moved to land over geologic time by the uplifting of Earth’s surface. (Figure 20.2.5)

Phosphorus is also reciprocally exchanged between phosphate dissolved in the ocean and marine organisms. The movement of phosphate from the ocean to the land and through the soil is extremely slow, with the average phosphate ion having an oceanic residence time between 20,000 and 100,000 years.

Excess phosphorus and nitrogen that enter these ecosystems from fertilizer runoff and from sewage cause excessive growth of algae. The subsequent death and decay of these organisms depletes dissolved oxygen, which leads to the death of aquatic organisms, such as shellfish and finfish. This process is responsible for dead zones in lakes and at the mouths of many major rivers and for massive fish kills, which often occur during the summer months (see Figure 20.2.6).

A dead zone is an area in lakes and oceans near the mouths of rivers where large areas are periodically depleted of their normal flora and fauna; these zones can be caused by eutrophication, oil spills, dumping toxic chemicals, and other human activities. The number of dead zones has increased for several years, and more than 400 of these zones were present as of 2008. One of the worst dead zones is off the coast of the United States in the Gulf of Mexico: fertilizer runoff from the Mississippi River basin created a dead zone of over 8,463 square miles. Phosphate and nitrate runoff from fertilizers also negatively affect several lake and bay ecosystems including the Chesapeake Bay in the eastern United States.

CAREERS IN ACTION: Chesapeake Bay

The Chesapeake Bay (Figure 20.2.7a) is one of the most scenic areas on Earth; it is now in distress and is recognized as a case study of a declining ecosystem. In the 1970s, the Chesapeake Bay was one of the first aquatic ecosystems to have identified dead zones, which continue to kill many fish and bottom-dwelling species such as clams, oysters, and worms. Several species have declined in the Chesapeake Bay because surface water runoff contains excess nutrients from artificial fertilizer use on land. The source of the fertilizers (with high nitrogen and phosphate content) is not limited to agricultural practices. There are many nearby urban areas and more than 150 rivers and streams empty into the bay that are carrying fertilizer runoff from lawns and gardens. Thus, the decline of the Chesapeake Bay is a complex issue and requires the cooperation of industry, agriculture, and individual homeowners.

Of particular interest to conservationists is the oyster population (Figure 20.2.7b); it is estimated that more than 200,000 acres of oyster reefs existed in the bay in the 1700s, but that number has now declined to only 36,000 acres. Oyster harvesting was once a major industry for Chesapeake Bay, but it declined 88 percent between 1982 and 2007. This decline was caused not only by fertilizer runoff and dead zones, but also because of overharvesting. Oysters require a certain minimum population density because they must be in close proximity to reproduce. Human activity has altered the oyster population and locations, thus greatly disrupting the ecosystem.

The restoration of the oyster population in the Chesapeake Bay has been ongoing for several years with mixed success. Not only do many people find oysters good to eat, but the oysters also clean up the bay. They are filter feeders, and as they eat, they clean the water around them. Filter feeders eat by pumping a continuous stream of water over finely divided appendages (gills in the case of oysters) and capturing prokaryotes, plankton, and fine organic particles in their mucus. In the 1700s, it was estimated that it took only a few days for the oyster population to filter the entire volume of the bay. Today, with the changed water conditions, it is estimated that the present population would take nearly a year to do the same job.

Restoration efforts have been ongoing for several years by non-profit organizations such as the Chesapeake Bay Foundation. The restoration goal is to find a way to increase population density so the oysters can reproduce more efficiently. Many disease-resistant varieties (developed at the Virginia Institute of Marine Science for the College of William and Mary) are now available and have been used in the construction of experimental oyster reefs. Efforts by Virginia and Delaware to clean and restore the bay have been hampered because much of the pollution entering the bay comes from other states, which emphasizes the need for interstate cooperation to gain successful restoration.

The new, hearty oyster strains have also spawned a new and economically viable industry—oyster aquaculture—which not only supplies oysters for food and profit, but also has the added benefit of cleaning the bay.

The Sulfur Cycle

Sulfur is an essential element for the macromolecules of living things. As part of the amino acid cysteine, it is involved in the formation of proteins. As shown in Figure 20.2.8, sulfur cycles between the oceans, land, and atmosphere. Atmospheric sulfur is found in the form of sulfur dioxide (SO2), which enters the atmosphere in three ways: first, from the decomposition of organic molecules; second, from volcanic activity and geothermal vents; and, third, from the burning of fossil fuels by humans.

On land, sulfur is deposited in four major ways: precipitation, direct fallout from the atmosphere, rock weathering, and geothermal vents (Figure 20.2.9). Atmospheric sulfur is found in the form of sulfur dioxide (SO2), and as rain falls through the atmosphere, sulfur is dissolved in the form of weak sulfuric acid (H2SO4). Sulfur can also fall directly from the atmosphere in a process called fallout. Also, as sulfur-containing rocks weather, sulfur is released into the soil. These rocks originate from ocean sediments that are moved to land by the geologic uplifting of ocean sediments. Terrestrial ecosystems can then make use of these soil sulfates (SO42-), which enter the food web by being taken up by plant roots. When these plants decompose and die, sulfur is released back into the atmosphere as hydrogen sulfide (H2S) gas.

Sulfur enters the ocean in runoff from land, from atmospheric fallout, and from underwater geothermal vents. Some ecosystems rely on chemoautotrophs using sulfur as a biological energy source. This sulfur then supports marine ecosystems in the form of sulfates.

Human activities have played a major role in altering the balance of the global sulfur cycle. The burning of large quantities of fossil fuels, especially from coal, releases larger amounts of hydrogen sulfide gas into the atmosphere. As rain falls through this gas, it creates the phenomenon known as acid rain, which damages the natural environment by lowering the pH of lakes, thus killing many of the resident plants and animals. Acid rain is corrosive rain caused by rainwater falling to the ground through sulfur dioxide gas, turning it into weak sulfuric acid, which causes damage to aquatic ecosystems. Acid rain also affects the man-made environment through the chemical degradation of buildings. For example, many marble monuments, such as the Lincoln Memorial in Washington, DC, have suffered significant damage from acid rain over the years. These examples show the wide-ranging effects of human activities on our environment and the challenges that remain for our future.

Section Summary

Mineral nutrients are cycled through ecosystems and their environment. All of these cycles have major impacts on ecosystem structure and function. As human activities have caused major disturbances to these cycles, their study and modeling is especially important. Ecosystems have been damaged by a variety of human activities that alter the natural biogeochemical cycles due to pollution, oil spills, and events causing global climate change. The health of the biosphere depends on understanding these cycles and how to protect the environment from irreversible damage.

Art Connections

Figure 20.2.4 Which of the following statements about the nitrogen cycle is false?

A. Ammonification converts organic nitrogenous matter from living organisms into ammonium (NH4+).
B. Denitrification by bacteria converts nitrates (NO3-) to nitrogen gas (N2).
C. Nitrification by bacteria converts nitrates (NO3-) to nitrites (NO2-).
D. Nitrogen fixing bacteria convert nitrogen gas (N2) into organic compounds.

C: Nitrification by bacteria converts nitrates (NO3-) to nitrites (NO2-).

Multiple Choice

The majority of the water found on Earth is:

A. ice
B. water vapor
C. fresh water
D. salt water

D

The process whereby oxygen is depleted by the growth of microorganisms due to excess nutrients in aquatic systems is called ________.

A. dead zoning
B. eutrophication
C. retrophication
D. depletion

B

Free Response

Why are drinking water supplies still a major concern for many countries?

Most of the water on Earth is salt water, which humans cannot drink unless the salt is removed. Some fresh water is locked in glaciers and polar ice caps, or is present in the atmosphere. The earth’s water supplies are threatened by pollution and exhaustion. The effort to supply fresh drinking water to the planet’s ever-expanding human population is seen as a major challenge in this century.

Footnotes

  1. 1 Scott L. Morford, Benjamin Z. Houlton, and Randy A. Dahlgren, “Increased Forest Ecosystem Carbon and Nitrogen Storage from Nitrogen Rich Bedrock,” Nature 477, no. 7362 (2011): 78–81.

Glossary

acid rain
a corrosive rain caused by rainwater mixing with sulfur dioxide gas as it fall through the atmosphere, turning it into weak sulfuric acid, causing damage to aquatic ecosystems
biogeochemical cycle
the cycling of minerals and nutrients through the biotic and abiotic world
dead zone
an area in a lake and ocean near the mouths of rivers where large areas are depleted of their normal flora and fauna; these zones can be caused by eutrophication, oil spills, dumping of toxic chemicals, and other human activities
eutrophication
the process whereby nutrient runoff causes the excess growth of microorganisms and plants in aquatic systems
fallout
the direct deposition of solid minerals on land or in the ocean from the atmosphere
hydrosphere
the region of the planet in which water exists, including the atmosphere that contains water vapor and the region beneath the ground that contains groundwater
non-renewable resource
a resource, such as a fossil fuel, that is either regenerated very slowly or not at all

Introduction to Remote Sensing Fifth Edition

1. History and Scope of Remote Sensing . 3
1.1. Introduction . 3

1.2. Definitions . 4
1.3. Milestones in the History of Remote Sensing . 7
1.4. Overview of the Remote Sensing Process . 18
1.5. Key Concepts of Remote Sensing . 19
1.6. Career Preparation and Professional Development . 21
1.7. Some Teaching and Learning Resources . 25
Review Questions . 27
References . 28


2. Electromagnetic Radiation . 31
2.1. Introduction . 31
2.2. The Electromagnetic Spectrum . 31
2.3. Major Divisions of the Electromagnetic Spectrum . 34
2.4. Radiation Laws . 36
2.5. Interactions with the Atmosphere . 38
2.6. Interactions with Surfaces . 48
2.7. Summary: Three Models for Remote Sensing . 54
2.8. Some Teaching and Learning Resources . 56
Review Questions . 56
References . 57


Part II. Image Acquisition

3. Mapping Cameras . 61
3.1. Introduction . 61
3.2. Fundamentals of the Aerial Photograph . 62
3.3. Geometry of the Vertical Aerial Photograph . 66
3.4. Digital Aerial Cameras . 72
3.5. Digital Scanning of Analog Images . 77
3.6. Comparative Characteristics of Digital and Analog Imagery . 78
3.7. Spectral Sensitivity . 79
3.8. Band Combinations: Optical Imagery
. 80
3.9. Coverage by Multiple Photographs . 84
3.10. Photogrammetry . 90
3.11. Sources of Aerial Photography . 91
3.12. Summary . 94
3.13. Some Teaching and Learning Resources . 94
Review Questions . 95
References . 95
Your Own Infrared Photographs . 97
Your Own 3D Photographs . 98
Your Own Kite Photography . 99


4. Digital Imagery . 101
4.1. Introduction . 101
4.2. Electronic Imagery . 101
4.3. Spectral Sensitivity . 106
4.4. Digital Data . 109
4.5. Data Formats . 111
4.6. Band Combinations: Multispectral Imagery . 115
4.7. Image Enhancement . 117
4.8. Image Display . 121
4.9. Image Processing Software . 125
4.10. Summary . 128
4.11. Some Teaching and Learning Resources . 128
Review Questions . 128
References . 129

5. Image Interpretation . 130
5.1. Introduction . 130
5.2. The Context for Image Interpretation . 131
5.3. Image Interpretation Tasks . 132
5.4. Elements of Image Interpretation . 133
5.5. Collateral Information . 138
5.6. Imagery Interpretability Rating Scales . 138
5.7. Image Interpretation Keys . 139
5.8. Interpretive Overlays . 139
5.9. The Significance of Context . 140
5.10. Stereovision . 143
5.11. Data Transfer . 147
5.12. Digital Photointerpretation . 147
5.13. Image Scale Calculations . 148
5.14. Summary . 151
5.15. Some Teaching and Learning Resources . 152
Review Questions . 152
References . 153


6. Land Observation Satellites . 158
6.1. Satellite Remote Sensing . 158
6.2. Landsat Origins . 159
6.3. Satellite Orbits . 160
6.4. The Landsat System . 162
6.5. Multispectral Scanner Subsystem . 167
6.6. Landsat Thematic Mapper . 172
6.7. Administration of the Landsat Program . 176
6.8. Current Satellite Systems . 178
6.9. Data Archives and Image Research . 192
6.10. Summary . 194
6.11. Some Teaching and Learning Resources . 195
Review Questions . 195
References . 196
CORONA . 198


7. Active Microwave . 204
7.1. Introduction . 204
7.2. Active Microwave . 204
7.3. Geometry of the Radar Image . 208
7.4. Wavelength . 212
7.5. Penetration of the Radar Signal . 212
7.6. Polarization . 214
7.7. Look Direction and Look Angle . 215
7.8. Real Aperture Systems . 217
7.9. Synthetic Aperture Systems . 219
7.10. Interpreting Brightness Values . 221
7.11. Satellite Imaging Radars . 226
7.12. Radar Interferometry. . 236
7.13. Summary .
. 239
7.14. Some Teaching and Learning Resources . 239
Review Questions . 240
References . 241

8. Lidar . 243
8.1. Introduction . 243
8.2. Profiling Lasers . 244
8.3. Imaging Lidars . 245
8.4. Lidar Imagery . 247
8.5. Types of Imaging Lidars . 247
8.6. Processing Lidar Image Data . 249
8.7. Summary . 253
8.8. Some Teaching and Learning Resources . 254
Review Questions . 254
References . 255

9. Thermal Imagery . 257
9.1. Introduction . 257
9.2. Thermal Detectors . 258


9.3. Thermal Radiometry . 260
9.4. Microwave Radiometers . 263
9.5. Thermal Scanners . 263
9.6. Thermal Properties of Objects . 265
9.7. Geometry of Thermal Images . 268
9.8. The Thermal Image and Its Interpretation . 269
9.9. Heat Capacity Mapping Mission . 277
9.10. Landsat Multispectral Scanner and Thematic Mapper
Thermal Data . 279
9.11. Summary . 280
9.12. Some Teaching and Learning Resources . 281
Review Questions . 282
References . 283

10. Image Resolution . 285
10.1. Introduction and Definitions . 285
10.2. Target Variables . 286
10.3. System Variables . 287
10.4. Operating Conditions . 287
10.5. Measurement of Resolution . 288
10.6. Mixed Pixels . 290
10.7. Spatial and Radiometric Resolution: Simple Examples . 294
10.8. Interactions with the Landscape . 296
10.9. Summary . 298
Review Questions . 298
References . 299


11. Preprocessing . 305
11.1. Introduction . 305
11.2. Radiometric Preprocessing . 305
11.3. Some More Advanced Atmospheric Correction Tools . 308
11.4. Calculating Radiances from DNs . 311
11.5. Estimation of Top of Atmosphere Reflectance . 312
11.6. Destriping and Related Issues . 313
11.7. Identification of Image Features . 316
11.8. Subsets . 320
11.9. Geometric Correction by Resampling . 321
11.10. Data Fusion . 326
11.11. Image Data Processing Standards . 329
11.12. Summary . 330
Review Questions . 330
References . 331


12. Image Classification . 335
12.1. Introduction . 335
12.2. Informational Classes and Spectral Classes . 337
12.3. Unsupervised Classification . 339
12.4. Supervised Classification . 349
12.5. Ancillary Data . 364
12.6. Fuzzy Clustering . 367
12.7. Artificial Neural Networks . 368
12.8. Contextual Classification . 370
12.9. Object-Oriented Classification . 371
12.10. Iterative Guided Spectral Class Rejection . 373
12.11. Summary . 373
12.12. Some Teaching and Learning Resources . 373
Review Questions . 374
References . 375


13. Field Data . 382
13.1. Introduction . 382
13.2. Kinds of Field Data . 382
13.3. Nominal Data . 383
13.4. Documentation of Nominal Data . 384
13.5. Biophysical Data . 384
13.6. Field Radiometry . 387
13.7. Unmanned Airborne Vehicles . 389
13.8. Locational Information . 392
13.9. Using Locational Information . 397
13.10. Ground Photography . 397
13.11. Geographic Sampling . 397
13.12. Summary
. 403
13.13. Some Teaching and Learning Resources . 403
Review Questions . 403
References . 404

14. Accuracy Assessment 408
14.1. Definition and Significance 408
14.2. Sources of Classification Error 410
14.3. Error Characteristics 411
14.4. Measurement of Map Accuracy 412
14.5. Interpretation of the Error Matrix 418
14.6. Summary 424
Review Questions 425
References 426


15. Hyperspectral Remote Sensing 429
15.1. Introduction 429
15.2. Spectroscopy 429
15.3. Hyperspectral Remote Sensing 430
15.4. The Airborne Visible/Infrared Imaging Spectrometer 430
15.5. The Image Cube 431
15.6. Spectral Libraries 432
15.7. Spectral Matching 433
15.8. Spectral Mixing Analysis 434

15.9. Spectral Angle Mapping 437
15.10. Analyses 437
15.11. Wavelet Analysis for Hyperspectral Imagery 438
15.12. Summary 439
Review Questions 440
References 441
16. Change Detection 445
16.1. Introduction 445

16.2. Bitemporal Spectral Change Detection Techniques 446
16.3. Multitemporal Spectral Change Detection 452
16.4. Summary 460
Review Questions 460
References 461

17. Plant Sciences 465
17.1. Introduction 465
17.2. Structure of the Leaf 470
17.3. Spectral Behavior of the Living Leaf 472
17.4. Forestry 476
17.5. Agriculture 479
17.6. Vegetation Indices 483
17.7. Applications of Vegetation Indices 484
17.8. Phenology 485
17.9. Advanced Very-High-Resolution Radiometer 487
17.10. Conservation Tillage 489
17.11. Land Surface Phenology 491
17.12. Separating Soil Reflectance from Vegetation Reflectance 493
17.13. Tasseled Cap Transformation 495
17.14. Foliar Chemistry 498

17.15. Lidar Data for Forest Inventory and Structure 500
17.16. Precision Agriculture 501
17.17. Remote Sensing for Plant Pathology 502
17.18. Summary 506
17.19. Some Teaching and Learning Resources 506
Review Questions 507
References 508

18. Earth Sciences 517
18.1. Introduction 517
18.2. Photogeology 518
18.3. Drainage Patterns 521
18.4. Lineaments 523
18.5. Geobotany 527
18.6. Direct Multispectral Observation of Rocks and Minerals 531
18.7. Photoclinometry 533

18.8. Band Ratios 534
18.9. Soil and Landscape Mapping 537
18.10. Integrated Terrain Units 540
18.11. Wetlands Inventory 542
18.12. Radar Imagery for Exploration 542
18.13. Summary 543
18.14. Some Teaching and Learning Resources 543
Review Questions 543
References 544


19. Hydrospheric Sciences 549
19.1. Introduction 549
19.2. Spectral Characteristics of Water Bodies 550
19.3. Spectral Changes as Water Depth Increases 553
19.4. Location and Extent of Water Bodies 555
19.5. Roughness of the Water Surface 557
19.6. Bathymetry 558
19.7. Landsat Chromaticity Diagram 564
19.8. Drainage Basin Hydrology 567
19.9. Evapotranspiration 570
19.10. Manual Interpretation 571
19.11. Sea Surface Temperature 575
19.12. Lidar Applications for Hydrospheric Studies 576
19.13. Summary 577
19.14. Some Teaching and Learning Resources 578
Review Questions 579
References 580


20. Land Use and Land Cover 585
20.1. Introduction 585
20.2. Aerial Imagery for Land Use Information 586
20.3. Land Use Classification 587
20.4. Visual Interpretation of Land Use and Land Cover 588
20.5. Land Use Change by Visual Interpretation 596
20.6. Historical Land Cover Interpretation for Environmental
Analysis 597
20.7. Other Land Use Classification Systems 599
20.8. Land Cover Mapping by Image Classification 601
20.9. Broad-Scale Land Cover Studies 603
20.10. Sources of Compiled Land Use Data 604
20.11. Summary 606
20.12. Some Teaching and Learning Resources 608
Review Questions 608
References 609


21. Global Remote Sensing 614
21.1. Introduction 614
21.2. Biogeochemical Cycles 614
21.3. Advanced Very-High-Resolution Radiometer 621

21.4. Earth Observing System 622
21.5. Earth Observing System Instruments 623
21.6. Earth Observing System Bus 627
21.7. Earth Observing System Data and Information System 629
21.8. Long-Term Environmental Research Sites 630
21.9. Earth Explorer 631
21.10. Global Monitoring for Environment and Security 632
21.11. Gridded Global Population Data 633
21.12. Summary 634
21.13. Some Teaching and Learning Resources 634
Review Questions 635
References 635
Conclusion. T he Outlook for the Field of Remote Sensing: 639
The View from 2011
Index 643
About the Authors 667


Seasonal Mixing-Driven System in Estuarine–Coastal Zone Triggers an Ecological Shift in Bacterial Assemblages Involved in Phytoplankton-Derived DMSP Degradation

The coastal zone has distinguishable but tightly connected ecosystems from rivers to the ocean and globally contributes to nutrient cycling including phytoplankton-derived organic matter. Particularly, bacterial contributions to phytoplankton-derived dimethylsulfoniopropionate (DMSP) degradation have been recently evaluated by using advanced sequencing technologies to understand their role in the marine microbial food web. Here, we surveyed the bacterial diversity and community composition under seasonal water mixing in the bay of Gwangyang (GW), a semi-enclosed estuary at the southern tip of the Korea Peninsula. We detected phylogenetic dissimilarities among season-specific habitats in GW and their specific bacterial taxa. Additionally, bacterial contribution to degradation of phytoplankton-derived DMSP from estuarine to coastal waters at euphotic depths in GW was investigated as the presence or absence of DMSP demethylation gene, encoded by dmdA. Among the operational taxonomic units (OTUs) in GW bacterial communities, the most dominant and ubiquitous OTU1 was affiliated with the SAR11 clade (SAR11-OTU). The population dynamics of SAR11-OTU in dmdA-detected GW waters suggest that water mass mixing plays a major role in shaping bacterial communities involved in phytoplankton-derived DMSP demethylation.

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2. Study Site

The study site (Figure  1 ) is located on the Alaska ACP between Teshekpuk Lake and the Alaska Beaufort Sea, about 120 km southeast of Utqiaġvik (Barrow), Alaska. Based on the thermokarst distribution and carbon stock synthesis by Olefeldt et al. (2016), the ACP belongs to the “Lake Thermokarst Landscapes.” This type is characterized by shallow thermokarst lakes, thermokarst lake basins, alas basins, and thaw sinks but also pingos as well as troughs and pits. Permafrost in this region is continuous and between 200 and 400 m thick (Jorgenson et al., 2008, 2011). North of Teshekpuk Lake represents the transition between the Outer Coastal Plain dominated by marine sands in the south and the Younger Outer Coastal Plain dominated by marine silts in the north (Black, 1964 Hinkel et al., 2005 Jorgenson et al., 2011 Kanevskiy et al., 2013 Williams et al., 1977, 1978).

Study area north of Teshekpuk Lake on the ACP. (a) Overview map of Alaska. (b) Landsat 8 mosaic of the thermokarst�ted ACP including Teshekpuk Lake 125 km southeast of Utqiaġvik, the northernmost city in the United States. (c) Study area (

150 km 2 ) and core locations in close vicinity to the Teshekpuk Lake Observatory. The study area was mapped into the prevailing landforms based on an IfSAR digital elevation model (Intermap, 2010) with 5‐m resolution and a false𠄌olor, infrared, aerial image orthomosaic (2.5‐m resolution, U.S. Geological Survey, 2002 see section 3.3). The DTLBs were classified into different stages of former lakes that drained fully or partially, forming overlapping basins.

The study region is dominated by drained thermokarst lake basins (which cover 62% of the ACP), thermokarst lakes (cover more 20% of the ACP) and primary surfaces (Arp et al., 2011 Hinkel et al., 2005 Jones & Arp, 2015). These primary surfaces (Brown, 1965) or erosional remnants (Eisner et al., 2005) have not been affected by Holocene thermokarst lake formation processes. However, the distinct upland surfaces are characterized by high ice contents, ice wedge polygons, organic‐rich Holocene cover deposits (Eisner et al., 2005) and cover 7% of the study area. Since these primary surfaces are at a slightly higher (about 5 m) elevation in a rather flat, low‐relief environment, we refer to these as uplands in this study. However in both, drained thermokarst lake basins and uplands of the ACP, the total ice volume in the ground may be up to 82% for DTLBs and 83% for uplands, respectively (Kanevskiy et al., 2013).

Mean annual air temperature is � ଌ (2004�) at the Drew Point site (70끑′N, 15끔′W) of the Global Terrestrial Network for Permafrost (Urban, 2017), and precipitation is low on the ACP with

200 mm/year (Arp et al., 2012 Jorgenson et al., 2011). According to the Circumpolar Arctic Vegetation Map (Walker et al., 2005) the area north of Teshekpuk Lake is classified into wetlands of bioclimatic subzone C, which is characterized by a mean July air temperature of 5𠄷 ଌ and dominated by wet graminoid, moss communities in nonacidic tundra (Raynolds et al., 2005, 2006).

Soils in DTLBs in the study region are mostly poorly drained with a 10 to 50 cm thick organic layer above silty loam (Jorgenson & Heiner, 2003 Ping, Lynn, et al., 2008). Ice‐rich permafrost is located near the surface, within the first meter of soil, and active layer (AL) thickness ranges from 20 to 73਌m (Bockheim & Hinkel, 2007). During our sampling period in mid‐July, thaw depths were not at their full extent and ranged from 22�਌m. Gelisol is the dominant soil type in the study region. The main soils in DTLBs are Typic Historthels and Glacic Aquorthels (Jorgenson et al., 2011 Ping, Lynn, et al., 2008). The two sampled transects (TES15‐T1 and TES15‐T3) include coring locations in nonpatterned DTLBs as well as in high�nter and low�nter polygons. Dominant soil types in high�nter polygons are Ruptic Histoturbels and Typic Histoturbels and in low�nter polygons Typic Histoturbels and Typic Historthels (Jorgenson et al., 2011 Ping, Lynn, et al., 2008).


Dynamics of periphyton nitrogen fixation in short-hydroperiod wetlands revealed by high-resolution seasonal sampling

Periphyton N2 fixation plays a key role in N cycling of aquatic systems, but temporal studies of this process are often lacking, especially in systems with only seasonal flooding. We used seven samplings to characterize nitrogenase activity (acetylene reduction method) of periphyton in short-hydroperiod marl prairies and two wetlands restored from agricultural disturbance in Everglades National Park, USA. We hypothesized that the seasonal drying and rewetting would increase the temporal dynamics of the process. All sites showed significant periphyton N2 fixation, but in restored areas highest rates were observed only in the early wet season (July), while in reference sites fixation was spread throughout the summer. Most N2 fixation in the restored areas was confined to a 3-month-period resulting in large underestimates of annual fixation in previous studies with few seasonal measurements. N2 fixation rates correlated with total P, N and TN:TP ratio, and periphyton moisture content in the dry season. N stable isotopic signature was a good indicator of N2 fixation rates between sites, but did not correctly indicate seasonal patterns. These findings improve our understanding of N cycling in wetlands like the Everglades and indicate a need for more detailed measurements of processes in seasonally flooded systems.

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Materials and methods

Ice base

From 15 March 2010 to 30 April 2010, the Catlin Ice Base (CIB) was situated on a region of flat, first-year sea ice, which extended east to west from Ellef Ringnes Island seaward (Fig. 1a, c). The thickness of the sea ice in the area was between 1.5 and 1.7 m. The science sampling site was located 2 km west of the CIB at 78° 42.69′ N, 104° 52.66′ W. An ice hole, 1.3 x 1.1 m in size, was made on 16 March 2010. The ice thickness at the hole was 1.52 m, with 0.2 m freeboard. The hole was covered with a Polar Chief tent to minimize freezing during sampling. The water depth under the ice was not precisely known, although the maximum depth of the wire on the winch used for obtaining samples was roughly 230 m. The Canadian Hydrographic Service Chart #7953 (last updated 17 March 1972) suggests that the area is between soundings of 290 and 420 m.

CIB meteorological measurements

A model 7425 Weather Wizard III meteorological station (Davis Instruments, Hayward, CA, USA) was set up at the CIB to measure wind speed, wind direction (from an anemometer placed 3 m above the sea ice) and shaded air temperature. These parameters were recorded twice daily (at 09:00 and 21:00, local time), as well as observations of cloud cover (oktas) and general weather conditions.

CIB seawater sampling

Seawater sampling was carried out through the ice hole every four days, starting on 17 March 2010 (Day of Year [DoY] 75) and ending on 26 April 2010 (DoY 115). Conductivity, temperature and depth measurements were made on each sample day using an SBE 19plus SeaCAT conductivity–temperature–depth (CTD) instrument (Sea-Bird Electronics, Bellevue, WA, USA), calibrated using bottle salinity samples analysed on an Autosal 8400B salinometer (Guildline Instruments, Smiths Falls, ON, Canada) at the Institute of Ocean Sciences, Sidney, Canada. Seawater was collected for analysis on each sample day from 1-, 3-, 5- and 10-m depths under the sea ice, using a 5-L Niskin bottle. Additionally, samples were taken at 100 and 200 m on 21 and 22 April 2010.

CIB sea-ice sampling

Four ice cores were collected from within 50 m of the water sampling hole on 8 and 13 April 2010 (DoY 97 and 102, respectively) using a 9-cm internal diameter ice corer (Kovacs Enterprises, Roseburg, OR, USA). A 1-m 2 area of ice was cleared of snow, and snow depth was measured at the edge of the cleared area. Once the cores were retrieved, ice thickness was measured using a tape measure with a weighted catch attachment deployed through the hole. The cores were immediately laid out on a cleaned PVC sled. Each core was then cut into sections using a clean stainless steel saw (starting from the top). Each piece was individually placed in a polyethylene, resealable, zip-seal bag and transported back to the CIB. Pieces from each of the “top,” “middle” and “bottom” sections of the core (Table 1) were then placed into gas-tight Tedlar bags, and a hand-pump was used to remove the headspace. The bagged sections were left in the dark to melt at room temperature, which took approximately 24 h. Once the ice melted, water samples were collected from each bag using methods described in a subsequent section for total inorganic carbon (CT), total alkalinity (AT), salinity, oxygen-18 (δO 18 ), nutrients and chlorophyll. The cold, brittleness of the ice and logistics prevented any additional cores from being collected.

Published online:

Table 1 Ice core collection data, size of each section (top, middle and bottom), total core length and snow cover.

Spatial transect from 85°N to 90°N

Spatial data of nutrients, chlorophyll, CT and AT were additionally collected through sea ice by a second team travelling on foot from 85°N to the North Pole (Fig. 1b) from 15 March 2010 to 12 May 2010, hereafter referred to as the Catlin Explorer Transect (CET). Seawater was collected through ice holes drilled with a Mora 110-mm ice auger (Rapala, Vääksy, Finland) and using a 1.2-L Kemmerer bottle from 1 m and 10 m under the sea ice. Duplicate CT/AT samples were collected into boreo-silicate square bottles with screw-cap lids and fixed with 100 µl of saturated HgCl2. These bottles were housed in specially designed warm boxes (adapted Yeti boxes) which had battery-operated heating mats placed in the bottoms to maintain the temperature above freezing. The samples were picked up from the expedition team and flown out on each resupply flight roughly every 18 days. Temperature and salinity profiles were made from the surface to approximately 30 m using an XR-420 CTD instrument (RBR, Kanata, ON, Canada) at each sampling location.

Sample processing and measurements

Chlorophyll

Seawater and ice-melts were filtered through grade GF/F filters (from the nutrient filtration), which were stored (frozen at −20°C) and returned to Plymouth Marine Laboratory, Plymouth, UK, for chlorophyll analysis. Each filter was placed in 90% v/v acetone and left for extraction at room temperature in the dark for 24 h. Concentrations of chlorophyll were measured using a model 10-AU fluorometer (Turner Designs, Sunnyvale, CA, USA) following US Joint Global Ocean Flux Study protocols (Knap et al. 1996 ).

Inorganic nutrients

Fifty millilitres of collected seawater and ice core meltwater were filtered (GF/F filters) into acid-cleaned, aged, 60-mL bottles (Nalgene, Rochester, NY, USA). Bottles were stored and shipped back frozen (−20°C) to land. Analysis was carried out at Plymouth Marine Laboratory (Woodward & Rees 2001 ) using a Bran & Luebbe AAIII segmented flow autoanalyser (SPX Flow Technology Norderstedt, Germany) for the colourimetric determination of inorganic nutrients: combined nitrate+nitrite (Brewer & Riley 1965 ), nitrite (Grasshoff 1976 ), phosphate (Zhang & Chi 2002 ), silicate (Kirkwood 1989 ) and ammonium (Mantoura & Woodward 1983 ). Nitrate concentrations were calculated by subtracting the nitrite from the combined nitrate+nitrite concentration.

Inorganic carbon

Seawater samples for total inorganic carbon (CT) and total alkalinity (AT) were collected in triplicate into 250-ml Duran glass bottles with ground glass stoppers for the 1-, 3-, 5- and 10-m samples according to Dickson et al. ( 2007 ). For the deep water samples (100 and 200 m) at the CIB wide-mouth, screw-cap glass bottles were used, while for the CET samples narrow-mouth, screw-cap bottles were used. For the melted ice cores, water was transferred from the Tedlar bags to 250-mL Duran glass bottles by attaching tubing to the valve inset in the bag and filling the bottles as recommended by Dickson et al. ( 2007 ). Samples were poisoned with 100 µL saturated HgCl2, as recommended by Dickson et al. ( 2007 ). Samples were stored at 4°C to the extent possible (sample storage temperature was difficult to control at the camp) in the dark and analysed at the Institute of Ocean Sciences within one year of collection, using VINDTA (Marianda, Kiel, Germany) and SOMMA (Marianda) instrumentation for CT and an open-cell potentiometric titration with non-linear least squares curve fitting for AT (Dickson et al. 2007 ). Batch 101 CRM (provided by Andrew Dickson, Scripps Institute of Oceanography) was used for calibration. Precision across CIB measurements was 2.3 µmol kg −1 for CT and 5.7 µmol kg −1 for AT. There was a decrease in the precision of the CT analysis (about 4 umol kg −1 ) for the CIB deep samples preserved in the wide-mouth, screw-cap bottle, likely because these bottles had greater potential for gas exchange during sampling, transport and analysis. Precision across CET measurements was 16 µmol kg −1 for CT and 20 µmol kg −1 for AT. Assuming that the deep water (100 and 200 m) samples from the CIB were supersaturated and the CET samples were slightly undersaturated, any errors associated with the screw-cap bottles will lead to underestimates for the deep water samples at the CIB and possibly smaller overestimates for the CET samples.

The seawater carbonate system programme CO2SYS (Pierrot et al. 2006 ) was used to calculate the CO2 partial pressure (pCO2) and pHT from CT, AT, in situ temperature, salinity and silicate and phosphate concentrations. Carbonic acid dissociation constants of Mehrbach et al. ( 1973 ) refit by Dickson & Millero ( 1987 ) and the constant of Dickson ( 1990 ) were used. These calculations were not made for the ice core melt samples.

Stable oxygen isotopes

Samples for 18 O: 16 O (reported as δO18) ratios from both water column and ice-melt samples were analysed by the G.G. Hatch Isotope Laboratories at the University of Ottawa, Ottawa, Canada, on a DeltaPlus XP isotope ratio mass spectrometer (Thermo Finnigan, San Jose, CA. USA) after headspace gas equilibration. The analytical precision was estimated to be 0.15 per mil.

Atmospheric CO2 and flux measurements

An eddy covariance system (ECS) was used to measure atmospheric CO2 and CO2 fluxes between the ice and the atmosphere. The ECS consisted of a closed-path LI7000 infrared gas analyser (Li-Cor Biosciences, Lincoln, NE, USA), sample pump, purge column, battery and CR5000 logger/signal unit (Campbell Scientific, Logan, UT, USA) housed in an insulated box container. A sonic anemometer and gas inlet pipe, with an external heat exchanger for equilibration of incoming air, were located at the top of a 3-m mast next to the control unit box. The ECS was sited approximately 230 m north-west of the main ice base on flat ice (snow depth <5 cm) between rubble ice regions 290 m to the south and 700 m to the north. The extreme cold conditions during the first 20 days of the expedition caused some difficulties with the ECS. However, the ECS was run successfully between 25 and 29 April 2010. ECS data were processed using EdiRe analysis software following the standard Euroflux guidelines (Aubinet et al. 2000 ). Because of the limited data availability, natural coordinate rotations (Tanner & Thurtell 1969 ) were employed for anemometer velocity data. The turbulent tube attenuation of Massman ( 1991 ) was employed in the frequency response corrections (Moore 1986 ). Fluxes were calculated for half-hour intervals and averaged to daily values assuming stationarity of environmental conditions. Data from the Alert atmospheric monitoring station (82° 27′ N, 62° 30′ W) were obtained to assess the quality of our ECS atmospheric pCO2 data and to obtain data for the period prior to 25 April 2010 (Dlugokencky et al. 2015 ).

Water column backscatter and current shear

A self-contained Workhorse Sentinel acoustic doppler current profiler (ADCP Teledyne RD Instruments, Poway, CA, USA) was mounted on an aluminium bar, anchored to the top of the ice and deployed just below the bottom of the ice to monitor acoustical backscatter and tidal currents. The instrument was operated nearly continuously for three days at the end of March, at 307 kHz, with bin sizes of 4 m and with the first bin at 6.09 m below the ice. Each ensemble was separated by 66 s and consisted of 50 transmissions, or pings. Because of the low concentration of scatterers in the water column the effective range of the instrument was approximately 45 m.


情報:農と環境と医療37号

Oxford University Press から1979年に「Gaia: A new look at life on earth」と題した本が出版された。この本が「地球生命圏"ガイアの科学」としてわが国で出版されたのは、1984年である。翻訳・出版されるのに5年の歳月が経っている。続いて、W.W. Nortonから1988年に「The ages of Gaia」が出版された。この本は「ガイアの時代」と題してわが国で1989年に翻訳・出版された。われわれは、原著出版の翌年にはこの本を翻訳文として読むことができた。

最近の原著「The REVENGE of GAIA」と訳書「ガイアの復讐」は、いずれも2006年である。われわれが翻訳文を手にしたのは、原著と同年ということになる。この3冊の本の原著と翻訳の時間的な流れをみるだけでも、ひとびとの地球生命圏ガイアへの関心の強さがうかがえる。さらに、地球が温暖化しつつある現実も、ひとびとの地球生命圏への関心を高めている。

第一次評価報告書1990では、気候変化の科学的評価WG I (温室効果ガスの増加と寄与率が重要)、気候変化の影響評価WG II、IPCC対応戦略WG III、気候変化:IPCC1990&1992評価第一次評価大要とSPM、が出版されている。

第二次評価報告書:気候変化1995では、気候変化の科学WG I 、気候変化の影響・適応・緩和:科学的及び技術的分析WG II (温室効果ガスの削減技術が重要)、気候変化の経済的・社会的側面WG III、UNFCC第2条の解釈における科学的・技術的情報に関する統合報告書(3作業部会のSPN)、が製本されている。

第三次評価報告書:気候変化2001では、科学的根拠WG I 、影響・適応・脆弱性WG II、緩和WG III、統合報告書、が出版されている。

温暖化:花綵列島への影響

時代と環境によって病気は異なる

重金属汚染による健康障害

WHOに報告されたヒトの高病原性鳥インフルエンザ(H5N1)感染確定症例数(A)と死亡例数(B)

ノーベル賞委員会は、1970年代から地球温暖化問題に取り組んでいるアル・ゴア前米副大統領とIPCC「Intergovernmental Panel on Climate Change:気候変動に関する政府間パネル」に、2007年のノーベル平和賞を授与した。このことによって、地球の温暖化問題が世界のひとびとの掌中に届いたことになる。

地球環境の変動は、いつの時代も食料を提供する農業と、人の健康と生命を守る医療に密接に関わっている。IPCCの報告書は、温暖化による健康影響の主要なものに次の現象を挙げている。(1) 熱ストレスによる死亡や熱中症など、(2) 洪水と旱魃を介する影響、(3) エルニーニョ現象との関連で発生する影響、(4)悪化する大気汚染による影響、(5)アレルギー疾患、(6)感染性疾患、(7)デング熱やその他アルボウイルスによる疾患、(8)リーシュマニア症(注:サシチョウバエが媒介する皮膚病)、(9)ダニ媒介性疾患、(10)げっ歯類によって媒介される伝染病、(11)飲料水に関連する疾患、(12)低栄養。

「医食同源」と「命のたべかた」と肥満

子ども達を含めてわれわれは、誰に、何に「いただきます」といっているのであろうか。神か仏か悪魔か、父母か料理人か百姓か、食料そのものか、はたまた Something Great か地球生命圏か雄大な大地か天空か海原か?

過日、「いのちの食べかた:OUR DAILY BREAD (Unser Taglich Brot)」という映画を観た。内容はこうである。われわれが常日頃口にしている食品が、食卓に並ぶまでの道のりを何の感情も入れず辿る。大量の野菜・果樹、牛・豚・鶏といった家畜が、どのように加工され食料になるかを追う。経済を主軸にし、効率化と自動化を追及した大農場や屠殺場を取材する完璧なドキュメンタリーである。

前段が長くなった。具体的な本書の紹介に入る。本書は、過敏性腸症候群(IBS: irritable bowel syndrome)という病態の解明を通し、脳と腸の間柄を深く考えることで、新しい生命観や人間像を描くものである。それも、具体的な事例を挙げて読者に理解してもらおうとする。

最後に「参考文献」が登場する。この種の本にはめずらしく、実に多くの内外の研究論文が紹介される。プロローグ、第1章、第2章、第3章、第4章、第5章、第6章、エピローグの参考文献は、それぞれ7, 31, 18, 17, 7, 16, 34および3点に及ぶ。各章をもう少し詳しく紹介する。

このような書き出しの後は、「QOLを低下させる症候群」(注:QOL= Quality of Life:生活の質)の項で、IBSはアメリカやイギリスなどストレスの多い先進国に多く、一種の文明病で、腸の機能の病気であることが解説される。最近の研究では、IBSの患者は脳と腸の情報のやりとりが過敏であることが分かってきた。

医という文字については、すでに「情報:農と環境と医療 17号」の「言葉の散策 1:医と医療の由来」で紹介したが、新たな知見を得たので再びここに登場させた。

  • ひさかたの 光のどけき 春の日に 静心なく 花の散るらん(紀 友則:平安前期)
  • ねがはくは 花の下にて 春死なむ その如月の 望月のころ(西行法師:1118-1190)
  • 敷島の 大和心を 人問はば 朝日に匂ふ 山桜花(本居宣長:1730-1801)

学生生活を始めるにあたって、Y = aX + bの数式のbという切片は問題にせず、aという傾きが重要で、学生たちの前途は、この傾きを増加させることできわめて明るいことを情熱をもって諭すことも必要であろう。


Watch the video: Mr. Walkers APES - Biogeochemical Cycles (January 2023).