1.
Lobaria pulmonaria
Its population has declined across Europe and L. pulmonaria is considered endangered in many lowland areas. The species has a history of use in medicines. It is a foliose lichen and its leaf-like thallus is green and lobed with a pattern of ridges, bright green under moist conditions, it becomes brownish and papery when dry. This species often has a fine layers of hairs, a tomentum, the cortex, the outer protective layer on the thallus surface, is roughly comparable to the epidermis of a green plant. The thallus is typically 5–15 centimetres in diameter, with individual lobes 1–3 centimetres wide, the asexual reproductive structures soredia and isidia are present on the thallus surface. Minute cephalodia—pockets of cyanobacteria—are often present on the surface of the thallus. Like other foliose lichens, the thallus is only attached to the surface on which it grows. The thallus contains internal structures known as cephalodia, characteristic of three-membered lichen symbioses involving two photobionts and these internal cephalodia, found between the ribs of the thallus surface, arise when blue-green algae on the thallus surface are enveloped during mycobiont growth.
Blue-green cyanobacteria can fix nitrogen, enhancing nutrient availability for the lichen. The other photobiont of L. pulmonaria is the green algae Dictyochloropsis reticulata, L. pulmonaria has the ability to form both vegetative propagation and sexual propagules at an age of about 25 years. In sexual reproduction, the species produces small reddish-brown discs known as apothecia containing asci, based on studies of ascospore germination, it has been suggested that L. Dispersal by vegetative propagules has been determined as the predominant mode of reproduction in L. pulmonaria. In this method, the protruding propagules become dry and brittle during the regular wet/dry cycles of the lichen and these fragments may develop into new thalli, either at the same locale or at a new site after dispersal by wind or rain. This steps lead to an increase in pressure which eventually breaks through the cortex. Continued growth leads to these granules being pushed upwards and out of the thallus surface and it has a wide distribution in Europe, North America and Africa, preferring damp habitats with high rainfall, especially coastal areas.
It is the most widely distributed and most common Lobaria species in North America, associated with old-growth forests, its presence and abundance may be used as an indicator of forest age, at least in the Interior Cedar-Hemlock biogeoclimatic zone in eastern British Columbia. It is found in pasture-woodlands and it usually grows on the bark of broad-leaved trees such as oak and maple but will grow on rocks. In the laboratory, L. pulmonaria has been grown on nylon microfilaments, various environmental factors are thought to affect the distribution of L. pulmonaria, such as temperature, sunlight exposure, and levels of air pollution. Due to declining population, L. pulmonaria is considered to be rare or threatened in parts of the world
2.
Gas exchange
Gas exchange is a biological process through which different gases are transferred in opposite directions across a specialized respiratory surface. Gases are constantly required by, and produced as a by-product of, cellular and metabolic reactions and it is linked with respiration in animals, and both respiration and photosynthesis in plants and some protista. In respiration, oxygen is required to enter cells, while carbon dioxide must be excreted. Respiration, which place in the mitochondria has four main steps, pyruvate oxidation. During the process of respiration, glucose is broken down into carbon dioxide and water, photosynthesis, is the process by which plants and some protista use light energy to produce glucose from CO2 and O2. This conversion is facilitated by the pigment called chlorophyll, found in the chloroplast organ of these organisms. In multicellular organisms, diffusion alone is not efficient, so specialised respiratory systems and this is the case for mammals, invertebrates, amphibians and protista, which have evolved circulatory systems.
These systems transport gases to and from the surface and maintain a continuous concentration gradient. Some multicellular organisms such as flatworms are large but very thin, another example of an organism which uses diffusion as a mechanism of gas exchange is the sponge. In order to produce ATP to survive, single-celled organisms organisms such as amoeba must be able to perform gas exchange, these organisms do not have specialised gas exchange surface, so single-celled organisms must take advantage of their high surface area. Their high surface area allows for gases to pass across the cell membrane, as organisms increase in size, so does the distance gases must travel across. In the case of single-celled organisms, the cell membrane distance will be 0. 1mm. It is a process, meaning that no energy is required. The alveolar and pulmonary capillary gases equilibrate across the blood–air barrier, the pulmonary alveoli consist of the alveolar epithelial cells, their basement membranes and the endothelial cells of the pulmonary capillaries.
This blood gas barrier is thin but extremely strong. This strength comes from the type IV collagen in between the endothelial and epithelial cells, damage can occur to this barrier at a pressure difference of around 5.3 kPa. The large surface area of the membrane comes from the folding of the membrane into 300 million alveoli, the branching of from the bronchioles in the lungs contributes to the extremely large surface area across which gas exchange can occur. The lungs of a person can contain between 2.5 and 3 liters of alveolar air
3.
Old-growth forest
Old-growth features include diverse tree-related structures that provide diverse wildlife habitat that increases the biodiversity of the forested ecosystem. The concept of tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters. Old-growth forests are valuable, and logging of these forests has been a point of contention between the logging industry and environmentalists. Old-growth forests tend to have trees and standing dead trees, multi-layered canopies with gaps that result from the deaths of individual trees. Depending on the forest, this may take anywhere from a century to several millennia, hardwood forests of the eastern United States can develop old-growth characteristics in one or two generations of trees, or 150–500 years. In British Columbia, old growth is defined as 120 to 140 years of age in the interior of the province where fire is a frequent and natural occurrence. In British Columbia’s coastal rainforests, old growth is defined as more than 250 years.
In Australia, eucalypt trees rarely exceed 350 years of age due to frequent fire disturbance, Forest types have very different development patterns, natural disturbances and appearances. Levels of biodiversity may be higher or lower in old-growth forests compared to that in second-growth forests, depending on circumstances, environmental variables. Logging in old-growth forests is an issue in many parts of the world. Excessive logging reduces biodiversity, affecting not only the old-growth forest itself, a forest in old-growth stage has a mix of tree ages, due to a distinct regeneration pattern for this stage. New trees regenerate at different times from other, because each one of them has different spatial location relative to the main canopy. The mixed age of the forest is an important criterion in ensuring that the forest is a stable ecosystem in the long term. A climax stand that is uniformly aged becomes senescent and degrades within a relatively short time-period to result in a new cycle of forest succession, uniformly aged stands are a less stable ecosystem.
Forest canopy gaps are essential in creating and maintaining mixed-age stands, some herbaceous plants only become established in canopy openings, but persist beneath an understory. Openings are a result of death due to small impact disturbances such as wind, low-intensity fires. Because old-growth forest is structurally diverse it provides higher-diversity habitat than forests in other stages, sometimes higher biological diversity can be sustained in old-growth forest, or at least a biodiversity that is different from other forest stages. The characteristic topography of much old-growth forest consists of pits and mounds, mounds are caused by decaying fallen trees, and pits by the roots pulled out of the ground when trees fall due to natural causes, including being pushed over by animals
4.
Fruticose lichen
A fruticose lichen is a form of lichen fungi that is characterized by a coral-like shrubby or bushy growth structure. It is composed of a thallus and a holdfast, the lichen is formed from a symbiotic relationship of a photobiont such as cyanobacteria and two mycobionts such as fungus. Fruticose lichen is characterized by an ascending, bushy or pendulous appearance, while lichen communities are mainly controlled by water and light, vegetative dispersal and filamentous growth in fruticose lichen is often associated with areas of low elevation. Fruticose lichens can endure high degrees of desiccation and they grow very slowly and will often occur in extreme habitats such as on tree barks, on rock surfaces and on soils in the Arctic and mountain regions. Fruticose lichen is a form of composed of a shrubby or bushy thallus. The thallus is the body of a lichen that does not have true leaves, stems. Thallus colour of the lichen can be attributed to the amount of light in its environment, a light thallus color is associated with lower light conditions within the growing environment.
Fruticose lichen is characterized by photobionts, the mode of dispersal, growth form. The lichens ability to survive extreme desiccation is due to its ability to quench excess light energy, characteristic of fruticose lichen is the shape of the thallus. Like crustose lichen, fruticose lichen is composed of a holdfast which will act as an anchor for the lichen to grow in rock fissures, over loose sand or soil. Fruticose or ‘shrubby’ lichen differ from other forms of lichen based on their form that is attached to the ground only at the base of the lichen. The most important difference that distinguishes fruticose lichen from other forms of lichen is the algal layer that grows around the circumference of the branches of the lichen. The thallus may be rounded or flattened, unbranched or branched. Fruticose lichens have a fine, hair-like structures and are attached to rocks. Although fruticose lichens are defined as being bushy, they can exhibit a flattened. Highly branched fruticose lichen have a surface to volume ratio that results in a rapid drying and wetting pattern compared to lichens that have a lower surface to volume ratio.
The internal structure of lichen is composed of a dense outer cortex, a thin algal layer, a medulla. The structure of fruticose lichens depends on their mycobionts, lichen undergoes diffuse growth and the thallus elongates over time
5.
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can be released to fuel the organisms activities. In most cases, oxygen is released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis, such organisms are called photoautotrophs, in plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, in the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate. Using the ATP and NADPH produced by the light-dependent reactions, the compounds are reduced and removed to form further carbohydrates. Cyanobacteria appeared later, the oxygen they produced contributed directly to the oxygenation of the Earth. Today, the rate of energy capture by photosynthesis globally is approximately 130 terawatts.
Photosynthetic organisms convert around 100–115 thousand million tonnes of carbon into biomass per year. Photosynthetic organisms are photoautotrophs, which means that they are able to synthesize food directly from carbon dioxide, not all organisms that use light as a source of energy carry out photosynthesis, photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon. In plants and cyanobacteria, photosynthesis releases oxygen and this is called oxygenic photosynthesis and is by far the most common type of photosynthesis used by living organisms. Although there are differences between oxygenic photosynthesis in plants and cyanobacteria, the overall process is quite similar in these organisms. There are varieties of anoxygenic photosynthesis, used mostly by certain types of bacteria. Carbon dioxide is converted into sugars in a process called carbon fixation, photosynthesis provides the energy in the form of free electrons that are used to split carbon from carbon dioxide that is used to fix that carbon once again as carbohydrate.
Carbon fixation is a redox reaction, so photosynthesis supplies the energy that drives both process. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP, during the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide. Most organisms that utilize oxygenic photosynthesis use visible light for the light-dependent reactions, some organisms employ even more radical variants of photosynthesis. Some archea use a method that employs a pigment similar to those used for vision in animals. The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump and this produces a proton gradient more directly, which is converted to chemical energy
6.
Mountain
A mountain is a large landform that stretches above the surrounding land in a limited area, usually in the form of a peak. A mountain is steeper than a hill. Mountains are formed through tectonic forces or volcanism and these forces can locally raise the surface of the earth. Mountains erode slowly through the action of rivers, weather conditions, a few mountains are isolated summits, but most occur in huge mountain ranges. High elevations on mountains produce colder climates than at sea level and these colder climates strongly affect the ecosystems of mountains, different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction and recreation, the highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8,850 m above mean sea level. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21,171 m, there is no universally accepted definition of a mountain.
Elevation, relief, steepness and continuity have been used as criteria for defining a mountain, whether a landform is called a mountain may depend on local usage. The highest point in San Francisco, California, is called Mount Davidson, notwithstanding its height of 300 m, Mount Scott outside Lawton, Oklahoma is only 251 m from its base to its highest point. Whittows Dictionary of Physical Geography states Some authorities regard eminences above 600 metres as mountains, in addition, some definitions include a topographical prominence requirement, typically 100 or 500 feet. For a while, the US defined a mountain as being 1,000 feet or taller, any similar landform lower than this height was considered a hill. However, the United States Geological Survey concludes that these terms do not have technical definitions in the US, using these definitions, mountains cover 33% of Eurasia, 19% of South America, 24% of North America, and 14% of Africa. As a whole, 24% of the Earths land mass is mountainous, there are three main types of mountains, volcanic and block.
All three types are formed from plate tectonics, when portions of the Earths crust move, compressional forces, isostatic uplift and intrusion of igneous matter forces surface rock upward, creating a landform higher than the surrounding features. The height of the feature makes it either a hill or, if higher and steeper, major mountains tend to occur in long linear arcs, indicating tectonic plate boundaries and activity. Volcanoes are formed when a plate is pushed below another plate, at a depth of around 100 km, melting occurs in rock above the slab, and forms magma that reaches the surface. When the magma reaches the surface, it builds a volcanic mountain. Examples of volcanoes include Mount Fuji in Japan and Mount Pinatubo in the Philippines, the magma does not have to reach the surface in order to create a mountain, magma that solidifies below ground can still form dome mountains, such as Navajo Mountain in the US
7.
Lichen
A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi in a symbiotic relationship. The combined lichen has properties different from those of its component organisms, Lichens come in many colours and forms. The properties are sometimes plant-like, but lichens are not plants, Lichens may have tiny, leafless branches, flat leaf-like structures, flakes that lie on the surface like peeling paint, or other growth forms. A macrolichen is a lichen that is either bush-like or leafy, here and micro do not refer to size, but to the growth form. Common names for lichens may contain the word moss, and lichens may superficially look like and grow with mosses, Lichens do not have roots that absorb water and nutrients as plants do, but like plants, they produce their own food by photosynthesis. When they grow on plants, they do not live as parasites, Lichens occur from sea level to high alpine elevations, in many environmental conditions, and can grow on almost any surface.
Lichens are abundant growing on bark, mosses, on other lichens and they grow on rock, gravestones, exposed soil surfaces, and in the soil as part of a biological soil crust. Different kinds of lichens have adapted to survive in some of the most extreme environments on Earth, arctic tundra, hot dry deserts, rocky coasts and they can even live inside solid rock, growing between the grains. It is estimated that 6% of Earths land surface is covered by lichen, there are about 20,000 known species of lichens. Some lichens have lost the ability to reproduce sexually, yet continue to speciate, Lichens may be long-lived, with some considered to be among the oldest living things. They are among the first living things to grow on fresh rock exposed after an event such as a landslide, the long life-span and slow and regular growth rate of some lichens can be used to date events. In American English, lichen is pronounced the same as the verb liken, in British English, both this pronunciation and one rhyming with kitchen /ˈlɪtʃən/) are used.
Lichens grow in a range of shapes and forms. The shape of a lichen is determined by the organization of the fungal filaments. The nonreproductive tissues, or vegetative body parts, is called the thallus, Lichens are grouped by thallus type, since the thallus is usually the most visually prominent part of the lichen. Thallus growth forms typically correspond to a few basic internal structure types, Common names for lichens often come from a growth form or color that is typical of a lichen genus. When a crustose lichen gets old, the center may start to crack up like old-dried paint, old-broken asphalt paving and this is called being rimose or areolate, and the island pieces separated by the cracks are called areolas. The areolas appear separated, but are connected by an underlying prothallus or hypothallus, when a crustose lichen grows from a center and appears to radiate out, it is called crustose placodioid
8.
Deer
Deer are the ruminant mammals forming the family Cervidae. The two main groups are the Cervinae, including the muntjac, the deer and the chital, and the Capreolinae, including the elk, the Western roe deer. Female reindeer, and male deer of all species, grow, in this they differ from permanently horned antelope, which are in the same order, Artiodactyla. The musk deer of Asia and water chevrotain of tropical African and Asian forests are not usually regarded as true deer and form their own families and Tragulidae, respectively. Deer appear in art from Palaeolithic cave paintings onwards, and they have played a role in mythology and their economic importance includes the use of their meat as venison, their skins as soft, strong buckskin, and their antlers as handles for knives. Deer hunting has been a sport since at least the Middle Ages. Deer live in a variety of biomes, ranging from tundra to the tropical rainforest, while often associated with forests, many deer are ecotone species that live in transitional areas between forests and thickets and prairie and savanna.
The majority of deer species inhabit temperate mixed deciduous forest, mountain mixed coniferous forest, tropical seasonal/dry forest. Clearing open areas within forests to some extent may actually benefit deer populations by exposing the understory and allowing the types of grasses, additionally, access to adjacent croplands may benefit deer. However, adequate forest or brush cover must still be provided for populations to grow, fallow deer have been introduced to South Africa. There are species of deer that are highly specialized, and live almost exclusively in mountains, swamps. Some deer have a distribution in both North America and Eurasia. Examples include the caribou that live in Arctic tundra and taiga and moose that inhabit taiga, huemul deer of South Americas Andes fill the ecological niches of the ibex and wild goat, with the fawns behaving more like goat kids. Mountain slope habitats vary from moist coniferous/mixed forested habitats to dry forests with alpine meadows higher up. The foothills and river valleys between the mountain provide a mosaic of cropland and deciduous parklands.
The rare woodland caribou have the most restricted range living at altitudes in the subalpine meadows. Elk and mule deer both migrate between the alpine meadows and lower coniferous forests and tend to be most common in this region, elk inhabit river valley bottomlands, which they share with White-tailed deer. They live in the aspen parklands north of Calgary and Edmonton, the adjacent Great Plains grassland habitats are left to herds of elk, American bison, and pronghorn antelope
9.
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new organisms arise without production of seeds or spores and it can occur naturally or be induced by horticulturists. Although most plants normally reproduce sexually, many have the ability for vegetative propagation and this is because meristematic cells capable of cellular differentiation are present in many plant tissues. Horticulturalists are interested in understanding how meristematic cells can be induced to reproduce an entire plant, success rates and difficulty of propagation vary greatly. For example and coleus can be propagated merely by inserting a stem in water or moist soil, on the other hand, unlike dicotyledons, typically lack a vascular cambium and therefore are harder to propagate. In a wide sense, methods of propagation include cutting, vegetative apomixis, division, grafting. Cutting exploits the ability of plants to grow adventitious roots under certain conditions, vegetative propagation is usually considered a cloning method.
However, there are cases where vegetatively propagated plants are not genetically identical. Root cuttings of thornless blackberries will revert to type because the adventitious shoot develops from a cell that is genetically thorny. Thornless blackberry is a chimera, with the epidermal layers genetically thornless, leaf cutting propagation of certain chimeral variegated plants, such as snake plant, will produce mainly nonvariegated plants. Grafting is often not a complete cloning method because seedlings are used as rootstocks, in that case only the top of the plant is clonal. In some crops, particularly apples, the rootstocks are vegetatively propagated so the entire graft can be if the scion. Apomixis is a type of reproduction that does not involve fertilisation, in flowering plants, unfertilized seeds are involved, or plantlets that grow instead of flowers. Hawkweed, some citrus and many such as Kentucky blue grass all use this form of asexual reproduction. Bulbils are sometimes formed instead of the flowers of garlic, virtually all types of shoots and roots are capable of vegetative propagation, including stems, basal shoots, rhizomes, corms and buds.
In a few species, leaves are involved in vegetative reproduction, the rhizome is a modified underground stem serving as an organ of vegetative reproduction, e. g. Polypodium, couch grass and nettles, prostrate aerial stems, called runners or stolons are important vegetative reproduction organs in some species, such as the strawberry, numerous grasses, and some ferns. Adventitious buds form on roots near the surface, on damaged stems
10.
Crustose lichen
Crustose lichens form a crust that strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a layer, an algal layer. The upper cortex layer is differentiated and is usually pigmented, the algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae, the surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes. Powdery – considered as the simplest subtype due to the absence of an organized thallus, genera Lepraria, Vezdaea Endolithic – grows inside the rock, usually in interstitial spaces between mineral grains. The upper cortex is usually developed, genus Lecidea Epilithic – grows on top of the rock without penetrating the rock substrate. Acarospora fuscata Epiphloeodal – grows only on the surface of plants, lecania naegelii Endophloeodic – grows underneath the cuticle of leaves or stems.
Amandinea punctata Squamulose – has a scale-like appearance resulting from partial separation from substrate and it is an intermediate form between crustose and foliose. Genus Psora, Coriscium Peltate – similar to squamulose, peltula euploca Bullate – has an extremely inflated appearance. Genus Mobergia Effigurate - has radially arranged marginal lobes that are prolonged, genera Acarospora, Pleopsidium Lobate – characterized by a thallus that radially arranged with lobes that are partially raised. Genera Caloplaca, Lecanora Suffruticose – clusters of coralloid cushions, peltula clavata Crustose lichen forms a thin crust adhering closely to the substratum. In some cases, this crust may be thick and lumpy, the thallus of a crustose lichen is usually only discernible because of the discolouration of the substrate. Some crustose lichens have thalli consisting of scattered or loosely grouped granules, Crustose lichens differ from the leprose lichen by having an upper cortex and algal cells that are located directly beneath the cortex.
The thallus of a lichen has a patchwork or crazy-paving appearance. The patches, or areolae, can be as large as 1 cm in diameter or very small and raised, the surface of the thallus is generally smooth, however it is sometimes broken up by “rimose” cracks. These cracks are a by-product of thallus surface shrinkage, which is caused by alternate wetting and drying, an underlayer of fungal hyphae, the hypothallus, is present on some species of crustose lichens. A dark rim on the areolae may form in areas where the hypothallus is exposed and this may be present on the thallus itself. These fungal hyphae are usually what attach the thallus firmly to the substrate, in general, lichens do not grow very quickly
11.
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. The smallest bird nests are those of hummingbirds, tiny cups which can be a mere 2 cm across. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m in diameter, not all bird species build nests. Most birds build a new nest each year, though some refurbish their old nests, the large eyries of some eagles are platform nests that have been used and refurbished for several years. In most species, the female does most or all of the nest construction, in some polygynous species, the male does most or all of the nest building. The nest may form a part of the display such as in weaver birds. The ability to choose and maintain good nest sites and build high quality nests may be selected for by females in these species, in some species the young from previous broods may act as helpers for the adults. Not every bird species builds or uses a nest, some auks, for instance—including common murre, thick-billed murre and razorbill—lay their eggs directly onto the narrow rocky ledges they use as breeding sites.
The eggs of species are dramatically pointed at one end. This is critical for the survival of the eggs, as there are no nests to keep them from rolling off the side of the cliff. Presumably because of the vulnerability of their eggs, parent birds of these auk species rarely leave them unattended. Nest location and architecture is influenced by local topography and other abiotic factors. King penguins and emperor penguins do not build nests, they tuck their eggs and they are thus able to move about while incubating, though in practice only the emperor penguin regularly does so. Without the ability to body heat, the penguins would expend far more energy trying to stay warm. Potoos lay their single egg directly atop a broken stump, or into a depression on a branch—typically where an upward-pointing branch died and fell off. Brood parasites, such as the New World cowbirds, the honeyguides, the simplest nest construction is the scrape, which is merely a shallow depression in soil or vegetation. This nest type, which typically has a rim deep enough to keep the eggs from rolling away, is lined with bits of vegetation, small stones.
Ostriches, most tinamous, many ducks, most shorebirds, most terns, some falcons, quail, bustards, brooding adults tend to be well camouflaged, and may be difficult to flush from the nest
12.
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides, common rust is a form of iron oxide. Iron oxides are used as inexpensive, durable pigments in paints, coatings. Colors commonly available are in the end of the yellow/orange/red/brown/black range. When used as a coloring, it has E number E172. Limonite Iron oxide nanoparticles List of inorganic pigments Information from Nano-Oxides, http, //chemed. chem. purdue. edu/demos/demosheets/12.3. html http, //minerals. usgs. gov/minerals/pubs/commodity/iron_oxide/ CDC - NIOSH Pocket Guide to Chemical Hazards de
