Chapter 2. Science, matter, energy and ecosystems: connections in nature

1. Chapter 2. Science, matter, energy and ecosystems: connections in nature Geog415 Dr Hengchun Ye

2. Science: is an attempt to discover the order in the natural world and use that knowledge to describe what is likely to happen in nature. Scientific hypothesis: an unconfirmed explanation of an observed phenomenon that can be tested by further research (peer review; reproducibility) Scientific theory: a verified, credible, and widely accepted scientific hypothesis or a related group of scientific hypothesis The real situation is more complicated because many variables or factors influence most process. So scientists conduct controlled experiment to isolate and study the effect of a single variable. Two Groups: (1) experimental group: the chosen variable is changes in a known way. (2) control group: the chosen variable is not changed. The difference between these two groups is considered as the results of this single variable impact. If need to assess a huge number of interacting variable, then use multivariable analysis, use mathematic models in computers. Outcome for scientific research (a) disprove things (2) establish that a particular theory or law has a very high probability or degree of certainty of being true.

3. Matter Matter: is anything that has mass and takes up space. It is made of elements and compound. Matter quality: how useful a form of matter is to us as a resource. High quality: concentrated, usually is found near the earth’s surface and has great potential for use as a matter resource. Low quality matter: dilute, often in deep underground or dispersed in the ocean or the atmosphere. It has little potential to use as a material resource. Material efficiency (or resource productivity): the total amount of material needed to produce each unit of goods or services. (will be greatly improved by 75-90% within 2 decades using existing technology.

4. Energy Energy: the capacity to do work and transfer heat. Kinetic energy: movement (wind, flowing water, electricity) Potential energy: stored and potentially available for us (book held in your hand, unlit match, chemical energy stored in gasoline molecules, etc) Electromagnetic radiation: energy traveling in the form of a wave as a result of the changes in electric and magnetic fields.

5. Energy-continue High quality energy: concentrated and can perform much useful work (electricity, chemical energy in the coal and gasoline, concentrated sunlight, nuclei of uranium-235-fule for nuclear power plant). Low-quality energy: dispersed and has little ability to do useful work. (heat dispersed in the moving molecules of a large amount of matter-air or water, so the temperature is low)

6. Laws The law of conservation of matter: in any physical and chemical change, matter is neither created nor destroyed but merely changed from one form to another; existing atoms are rearranged into different spatial patterns of different combinations. Things we threw away are always still there. They may be changed into a less harmful forms. First law of thermal dynamics: energy can be changed from one form to another but can never be crated or destroyed (we cannot get something from nothing) Second law of thermal dynamics: when energy is changed from one form to another, some of the useful energy is always degraded to lower-quality, more dispersed, less useful energy. (cannot break even in terns of energy quality) Energy efficiency (productivity): a measure of how much useful work is accomplished by a particular input of energy into system (about 43% unnecessarily waste). We can never recycle or reuse high-quality energy to perform useful work, but there are lots of rooms to improve energy efficiency (productivity)

7. Earth’s life support system Ecology: the study of how organisms interact with one another and with their non-living environment. (organisms made of cells and classified into species-a form of life) Species: groups of organisms that resemble one another in appearance, behavior, chemistry, and genetic makeup (under natural conditions, they can breed with one another and produce live, fertile offspring) Microbes (microorganism): a term for many thousands of species of bacteria, protozoa (a group of unicell animals in different morphology present in most habitats including the parasitic), fungi, and yeasts-most too small to be seen with the naked eye. Harmful microbes are minority (3.6 million to 100 million species on the earth). Examples: in soil to fix nitrogen from the air; in food such as bread, cheese, yogurt, vinegar, tofu, soy sauce, beer, and wine. Bacteria help purify water by breaking down the wastes, in intestinal track break down the food you eat; control plant disease and insect species that attack food crops, help clean toxic waste sites. Insects: sustaining life on the earth by pollinating plants that provide food, and eating insects that we classify as pests. Have been around for 400 million years, reproduce at astounding rate and rapidly evolve new genetic traits (resistance to pesticides), very resistance to extinction. They can survive without us, but we cannot live without them. Example. A single female housefly and her offspring can theoretically produce about 5.6 trillion flies in one year.

8. Earth’s life supporting system-continue Population: a group of interacting individual or organisms of the same species occupying a specific area. Population’s genetic diversity: individuals vary slightly in their genetic makeup and do not all look or act alike Community (biological community): consists of all the populations of the different species living and interacting in an area (network of plants, animals ands microorganisms). Ecosystem: is a community of different species interacting with one another and with their physical environment of matter and energy. Example: a puddle of water, a stream, a patch of woods, forest, etc. Crop field, farm ponds and reservoirs are artificial ecosystems. Biosphere is made of ecosystem.

9. Four life supporting systems: atmosphere, hydrosphere, lithosphere, and biosphere. Two components in biosphere and its ecosystem: Abiotic: nonliving components such as water, air, nutrients, and solar energy) Biotic: plants, animals, and microbes

10. Law of tolerance: the existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by that species. A species may have a wide range of tolerant to some factors but narrow to others. Most species are least tolerant during juvenile or reproductive stages of their life cycles. Limiting factor principle: too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance. For land, limiting factor may be water, soil nutrients For aquatic life: temperature, sunlight, nutrient availability, salinity and dissolved oxygen content.

11. Solar energy Albedo: the percentage of solar radiation reflected by a surface