Misplaced Pages

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109-437: The creek was the site of heavy industrial use throughout much of the 20th century, being home to quarries, landfills and accepting waste runoff from neighbouring factories. This has degraded the riparian ecology of the creek leaving behind pollutants such as heavy metals and various greases . Recent decades have seen some regenerative planting and the foundation of several community groups dedicated to protecting and regenerating

218-474: A willow control program to improve water flows and allow for the revegetation of sites with indigenous plant species. At times of low flow, water is sustained in the creek through treated outfall from the Craigieburn sewage treatment plant, [1] . Water quality was thought to have been insufficient to allow repopulation by platypus , as industrial toxicants have reduced macroinvertebrate productivity to

327-587: A basal rosette of leaves and a central taproot. However, the leaves of dandelions are smooth or glabrous, whereas those of cat's ears are coarsely hairy. Early-flowering dandelions may be distinguished from coltsfoot ( Tussilago farfara ) by their basal rosette of leaves, their lack of disc florets, and the absence of scales on the flowering stem. Other plants with superficially similar flowers include hawkweeds ( Hieracium ) and hawksbeards ( Crepis ). These are readily distinguished by branched flowering stems, which are usually hairy and bear leaves. The genus

436-464: A cultivar of the Russian dandelion that is suitable for current commercial production of natural rubber. The latex produced exhibits the same quality as the natural rubber from rubber trees . In collaboration with Continental AG , IME is building a pilot facility. As of May 2014 , the first prototype test tires made with blends from dandelion-rubber are scheduled for testing on public roads over

545-596: A dandelion patch over two years (59.2 and 8.9 flowers per square metre (5.50 and 0.83/sq ft) in 1981 and 1982). He measured average nectar volume at 7.4 μl /flower in 1981 and 3.7 μl/flower in 1982. The flowers tended to open in the morning and close in the afternoon with the concentrations significantly higher on the second day. Dandelions are used as food plants by the larvae of some species of Lepidoptera ( butterflies and moths ). Dandelions can cause significant economic damage as an invasive species and infestation of other crops worldwide; in some jurisdictions,

654-493: A given metal ion. This scheme has been applied to analyze biologically active metals in sea water for example, but it has not been widely adopted. The heaviness of naturally occurring metals such as gold , copper , and iron may have been noticed in prehistory and, in light of their malleability , led to the first attempts to craft metal ornaments, tools, and weapons. In 1817 the German chemist Leopold Gmelin divided

763-422: A gray area. Class A metal ions prefer oxygen donors; class B ions prefer nitrogen or sulfur donors; and borderline or ambivalent ions show either class A or B characteristics, depending on the circumstances. The distinction between the class A metals and the other two categories is sharp. The class A and class B terminology is analogous to the "hard acid" and "soft base" terminology sometimes used to refer to

872-413: A head is called a floret . In part due to their abundance, along with being a generalist species , dandelions are one of the most vital early spring nectar sources for a wide host of pollinators . Many Taraxacum species produce seeds asexually by apomixis , where the seeds are produced without pollination , resulting in offspring that are genetically identical to the parent plant. In general,

981-934: A heavy metal rare-earth like series ...". The counterparts to the heavy metals, the light metals , are defined by The Minerals, Metals and Materials Society as including "the traditional ( aluminium , magnesium , beryllium , titanium , lithium , and other reactive metals) and emerging light metals (composites, laminates, etc.)" Trace amounts of some heavy metals, mostly in period 4, are required for certain biological processes. These are iron and copper ( oxygen and electron transport ); cobalt ( complex syntheses and cell metabolism ); zinc ( hydroxylation ); vanadium and manganese ( enzyme regulation or functioning); chromium ( glucose utilisation); nickel ( cell growth ); arsenic (metabolic growth in some animals and possibly in humans) and selenium ( antioxidant functioning and hormone production). Periods 5 and 6 contain fewer essential heavy metals, consistent with

1090-974: A journey along the ancestral valleys of the Merri and Darebin Creeks and into the valley of the Yarra River as far as the Melbourne CBD. The modern day Merri Creek was formed over many years by incising through the lava surface. Today, the creek begins in Wallan and flows in a southerly direction for 70 km until it joins the Yarra River in Fairfield near Dights Falls and subsequently flows into Port Phillip Bay . Its tributaries include Wallan Creek, Mittagong Creek, Taylors Creek, Malcolm Creek, Aitken Creek, Curly Sedge Creek, Central Creek, Merlynston Creek and Edgars Creek . It flows through, or forms

1199-560: A large area. Dandelions secrete latex when the tissues are cut or broken, yet in the wild type, the latex content is low and varies greatly. Taraxacum kok-saghyz , the Russian dandelion, is a species that produced industrially useful amounts during WW2. Using modern cultivation methods and optimization techniques, scientists in the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) in Germany developed

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1308-419: A long history of consumption. The common name dandelion ( / ˈ d æ n d ə l aɪ . ən / DAN -də-ly-ən ; from French dent-de-lion  'lion's tooth', referring to the jagged leaves) is also given to specific members of the genus . Like other members of the family Asteraceae, they have very small flowers collected together into a composite flower head . Each single flower in

1417-511: A lower atomic number) by neutron capture , with the two main modes of this repetitive capture being the s-process and the r-process . In the s-process ("s" stands for "slow"), singular captures are separated by years or decades, allowing the less stable nuclei to beta decay , while in the r-process ("rapid"), captures happen faster than nuclei can decay. Therefore, the s-process takes a more or less clear path: for example, stable cadmium-110 nuclei are successively bombarded by free neutrons inside

1526-650: A metalloid), have replaced lead and antimony in the green bullets used by some armies and in some recreational shooting munitions. Doubts have been raised about the safety (or green credentials ) of tungsten. Because denser materials absorb more of certain types of radioactive emissions such as gamma rays than lighter ones, heavy metals are useful for radiation shielding and to focus radiation beams in linear accelerators and radiotherapy applications. The strength or durability of heavy metals such as chromium, iron, nickel, copper, zinc, molybdenum, tin, tungsten, and lead, as well as their alloys, makes them useful for

1635-760: A much narrower view and only accept a total of about 60 (macro)species. By 2015, the number has been revised to include 60 sections and about 2800 microspecies. 30 of these sections are known to reproduce sexually. About 235 apomictic and polyploid microspecies have been recorded in Great Britain and Ireland alone. Botanists specialising in the genus Taraxacum are sometimes called taraxacologists, for example Gunnar Marklund , Johannes Leendert van Soest or A.J. Richards. Dandelions are thought to have evolved about 30 million years ago in Eurasia . Fossil seeds of Taraxacum tanaiticum have been recorded from

1744-465: A part of the borders between the suburbs of Wallan, Kalkallo , Donnybrook , Craigieburn , Wollert , Epping , Somerton , Campbellfield , Lalor , Thomastown , Fawkner , Reservoir , Coburg North , Coburg , Preston , Thornbury , Brunswick East , Northcote , Westgarth , Fitzroy North , Clifton Hill and Fairfield before meeting the Yarra River just upstream of Dights Falls . One of

1853-412: A result of a neutron star merger, thereby increasing the abundance of elements heavier than helium in the interstellar medium . When gravitational attraction causes this matter to coalesce and collapse, new stars and planets are formed . The Earth's crust is made of approximately 5% of heavy metals by weight, with iron comprising 95% of this quantity. Light metals (~20%) and nonmetals (~75%) make up

1962-484: A separated vortex ring. This work provided evidence that dandelion seeds have fluid behavior around fluid-immersed bodies that may help understand locomotion, weight reduction and particle retention in biological and man-made structures. In 2022, researchers at the University of Washington demonstrated battery-free wireless sensors and computers that mimic dandelion seeds and can float in the wind and disperse across

2071-402: A siderophile, is most commonly recovered by dissolving the ores in which it is found in a cyanide solution . The gold forms a dicyanoaurate(I), for example: 2 Au + H 2 O +½ O 2 + 4 KCN → 2 K[Au(CN) 2 ] + 2 KOH . Zinc is added to the mix and, being more reactive than gold, displaces the gold: 2 K[Au(CN) 2 ] + Zn → K 2 [Zn(CN) 4 ] + 2 Au. The gold precipitates out of solution as

2180-575: A significant degree, of heavy metals such as chromium, nickel, cadmium, or lead. Copper, zinc, tin, and lead are mechanically weaker metals but have useful corrosion prevention properties. While each of them will react with air, the resulting patinas of either various copper salts, zinc carbonate , tin oxide , or a mixture of lead oxide , carbonate , and sulfate , confer valuable protective properties . Copper and lead are therefore used, for example, as roofing materials ; zinc acts as an anti-corrosion agent in galvanised steel ; and tin serves

2289-1352: A similar purpose on steel cans . The workability and corrosion resistance of iron and chromium are increased by adding gadolinium ; the creep resistance of nickel is improved with the addition of thorium. Tellurium is added to copper ( tellurium copper ) and stainless steel to improve their machinability; and to lead to make it harder and more acid-resistant. The biocidal effects of some heavy metals have been known since antiquity. Platinum, osmium, copper, ruthenium, and other heavy metals, including arsenic, are used in anti-cancer treatments, or have shown potential. Antimony (anti-protozoal), bismuth ( anti-ulcer ), gold ( anti-arthritic ), and iron ( anti-malarial ) are also important in medicine. Copper, zinc, silver, gold, or mercury are used in antiseptic formulations; small amounts of some heavy metals are used to control algal growth in, for example, cooling towers . Depending on their intended use as fertilisers or biocides, agrochemicals may contain heavy metals such as chromium, cobalt, nickel, copper, zinc, arsenic, cadmium, mercury, or lead. Selected heavy metals are used as catalysts in fuel processing (rhenium, for example), synthetic rubber and fibre production (bismuth), emission control devices (palladium and platinum), and in self-cleaning ovens (where cerium(IV) oxide in

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2398-438: A sludge, and is filtered off and melted. Heavy metals are present in nearly all aspects of modern life. Iron may be the most common as it accounts for 90% of all refined metals. Platinum may be the most ubiquitous given it is said to be found in, or used to produce, 20% of all consumer goods. Some common uses of heavy metals depend on the general characteristics of metals such as electrical conductivity and reflectivity or

2507-443: A species endemic to Crete, is eaten in the same way; it is found only at high altitudes (1,000–1,600 metres (3,300–5,200 ft)) and in fallow sites, and is called pentaramia ( πενταράμια ) or agrioradiko ( αγριοράδικο ). The flower petals , along with other ingredients, usually including citrus , are used to make dandelion wine . Its ground, roasted roots can be used as a caffeine-free coffee alternative . Dandelion

2616-399: A star until they form cadmium-115 nuclei which are unstable and decay to form indium-115 (which is nearly stable, with a half-life 30,000 times the age of the universe). These nuclei capture neutrons and form indium-116, which is unstable, and decays to form tin-116, and so on. In contrast, there is no such path in the r-process. The s-process stops at bismuth due to the short half-lives of

2725-974: A statistically significant correlation between the usage rate of leaded gasoline and violent crime in the United States; taking into account a 22-year time lag (for the average age of violent criminals), the violent crime curve virtually tracked the lead exposure curve. Other heavy metals noted for their potentially hazardous nature, usually as toxic environmental pollutants, include manganese (central nervous system damage); cobalt and nickel (carcinogens); copper, zinc, selenium and silver ( endocrine disruption, congenital disorders , or general toxic effects in fish, plants, birds, or other aquatic organisms); tin, as organotin (central nervous system damage); antimony (a suspected carcinogen); and thallium (central nervous system damage). A few other non-essential heavy metals have one or more toxic forms. Kidney failure and fatalities have been recorded arising from

2834-423: A strong affinity for oxygen and mostly exist as relatively low density silicate minerals . Chalcophile heavy metals are mainly the less reactive d-block elements, and period 4–6 p-block metals and metalloids. They are usually found in (insoluble) sulfide minerals . Being denser than the lithophiles, hence sinking lower into the crust at the time of its solidification, the chalcophiles tend to be less abundant than

2943-480: A substantial amount of the prebiotic fiber inulin . Dandelion greens contain lutein . Taraxalisin , a serine proteinase , is found in the latex of dandelion roots. Maximal activity of the proteinase in the roots is attained in April, at the beginning of plant development after the winter period. Each dandelion seed has a mass(weight) of 500 micrograms or 0.0005g (1/125 of a grain). The entire plant, including

3052-422: A term for toxic substances To be an acceptable term in scientific papers, a strict definition has been encouraged. Even in applications other than toxicity, there no widely agreed criterion-based definition of a heavy metal. Reviews have recommended that it not be used. Different meanings may be attached to the term, depending on the context. For example, a heavy metal may be defined on the basis of density ,

3161-443: A wide range of uses, the dandelion is cultivated in small gardens to massive farms. It is kept as a companion plant ; its taproot brings up nutrients for shallow-rooting plants. It is also known to attract pollinating insects and release ethylene gas, which helps fruit to ripen. It has been a Western tradition for someone to blow out a dandelion seedhead and think of a wish they want to come true. Five dandelion flowers are

3270-421: Is taxonomically complex due to the presence of apomixis: any morphologically distinct clonal population would deserve its own microspecies . Phylogenetic approaches are also complicated by the accelerated mutation in apomixic lines and repeated ancient hybridization events in the genus. As of 1970, the group is divided into about 34 macrospecies or sections , and about 2000 microspecies ; some botanists take

3379-512: Is a corruption of the French dent de lion meaning "lion's tooth", referring to the coarsely toothed leaves. The plant is also known as blowball, cankerwort, doon-head-clock, witch's gowan, milk witch, lion's-tooth, yellow-gowan, Irish daisy, monks-head, priest's-crown, and puff-ball; other common names include faceclock , pee-a-bed , wet-a-bed , swine's snout , white endive, and wild endive. The English folk name " piss-a-bed " (and indeed

Merri Creek - Misplaced Pages Continue

3488-544: Is a popular destination for residents taking walks and other leisure activities, and is considered a "green oasis" in the northern suburbs. Patches of remnant native flora still remain along the creek, and their quality has improved through weed control and ecological burning. Much native vegetation has been replanted by the Merri Creek Management Committee and the volunteer group Friends of Merri Creek . Melbourne Water has been involved in

3597-523: Is about 0.01% heavy metals (~7 g, equivalent to the weight of two dried peas, with iron at 4 g, zinc at 2.5 g, and lead at 0.12 g comprising the three main constituents), 2% light metals (~1.4 kg, the weight of a bottle of wine) and nearly 98% nonmetals (mostly water ). A few non-essential heavy metals have been observed to have biological effects. Gallium , germanium (a metalloid), indium, and most lanthanides can stimulate metabolism, and titanium promotes growth in plants (though it

3706-629: Is also a kidney and nerve poison. Bismuth compounds can cause liver damage if taken in excess; insoluble uranium compounds, as well as the dangerous radiation they emit, can cause permanent kidney damage. Heavy metals can degrade air, water, and soil quality , and subsequently cause health issues in plants, animals, and people, when they become concentrated as a result of industrial activities. Common sources of heavy metals in this context include vehicle emissions; motor oil; fertilisers; glassworking; incinerators; treated timber ; aging water supply infrastructure ; and microplastics floating in

3815-419: Is also abundant in edible plants, although care should be taken when attempting to identify them. including dandelion , dock , fennel , jerusalem artichoke , numerous brassicas , blackberry nightshade , sorrel , catsear , sowthistle , nettle and many others. Caution is advisable when harvesting fennel and other members of the family Apiaceae , as poison hemlock has been found growing in some areas of

3924-406: Is attached to a pappus of fine hair-like material which enables anemochorous (wind-aided) dispersal over long distances. The flower head is surrounded by bracts (sometimes mistakenly called sepals ) in two series. The inner bracts are erect until the seeds mature, then flex downward to allow the seeds to disperse. The outer bracts are often reflexed downward, but remain appressed in plants of

4033-624: Is both meaningless and misleading". The IUPAC report focuses on the legal and toxicological implications of describing "heavy metals" as toxins when there is no scientific evidence to support a connection. The density implied by the adjective "heavy" has almost no biological consequences and pure metals are rarely the biologically active substance. This characterization has been echoed by numerous reviews. The most widely used toxicology textbook, Casarett and Doull’s toxicology uses "toxic metal" not "heavy metals". Nevertheless many scientific and science related articles continue to use "heavy metal" as

4142-487: Is important in the construction of mirrors , including precision astronomical instruments . Headlight reflectors rely on the excellent reflectivity of a thin film of rhodium. Heavy metals or their compounds can be found in electronic components , electrodes , and wiring and solar panels where they may be used as either conductors, semiconductors, or insulators. Molybdenum powder is used in circuit board inks. Ruthenium(IV) oxide coated titanium anodes are used for

4251-464: Is instead obtained from spent nuclear fuels . The chalcophile platinum group metals (PGM) mainly occur in small (mixed) quantities with other chalcophile ores. The ores involved need to be smelted , roasted, and then leached with sulfuric acid to produce a residue of PGM. This is chemically refined to obtain the individual metals in their pure forms. Compared to other metals, PGM are expensive due to their scarcity and high production costs. Gold,

4360-466: Is located just off the adjoining trail in Clifton Hill. Heavy metals Heavy metals is a controversial and ambiguous term for metallic elements with relatively high densities , atomic weights , or atomic numbers . The criteria used, and whether metalloids are included, vary depending on the author and context and has been argued should not be used. A heavy metal may be defined on

4469-411: Is not always considered a heavy metal). Heavy metals are often assumed to be highly toxic or damaging to the environment. Some are, while certain others are toxic only if taken in excess or encountered in certain forms. Inhalation of certain metals, either as fine dust or most commonly as fumes, can also result in a condition called metal fume fever . Chromium, arsenic, cadmium, mercury, and lead have

Merri Creek - Misplaced Pages Continue

4578-1023: Is sometimes quoted as a commonly used criterion and is used in the body of this article. The earliest known metals—common metals such as iron , copper , and tin , and precious metals such as silver , gold , and platinum —are heavy metals. From 1809 onward, light metals , such as magnesium , aluminium , and titanium , were discovered, as well as less well-known heavy metals including gallium , thallium , and hafnium . Some heavy metals are either essential nutrients (typically iron, cobalt , copper and zinc ), or relatively harmless (such as ruthenium , silver and indium ), but can be toxic in larger amounts or certain forms. Other heavy metals, such as arsenic , cadmium , mercury, and lead, are highly poisonous. Potential sources of heavy metal poisoning include mining , tailings , smelting , industrial waste , agricultural runoff , occupational exposure , paints and treated timber . Physical and chemical characterisations of heavy metals need to be treated with caution, as

4687-410: Is treated as a nonmetal. The United States Pharmacopeia includes a test for heavy metals that involves precipitating metallic impurities as their coloured sulfides . On the basis of this type of chemical test, the group would include the transition metals and post-transition metals . A different chemistry-based approach advocates replacing the term "heavy metal" with two groups of metals and

4796-451: Is used as a voltage controller in microchips ; tantalum oxide , another insulator, is used in capacitors in mobile phones . Heavy metals have been used in batteries for over 200 years, at least since Volta invented his copper and silver voltaic pile in 1800. Magnets are often made of heavy metals such as manganese, iron, cobalt, nickel, niobium, bismuth, praseodymium, neodymium, gadolinium, and dysprosium . Neodymium magnets are

4905-555: Is used in armour plating and armour piercing projectiles , as well as in nuclear weapons to increase efficiency (by reflecting neutrons and momentarily delaying the expansion of reacting materials). In the 1970s, tantalum was found to be more effective than copper in shaped charge and explosively formed anti-armour weapons on account of its higher density, allowing greater force concentration, and better deformability. Less- toxic heavy metals , such as copper, tin, tungsten, and bismuth, and probably manganese (as well as boron ,

5014-489: The Mayflower for their supposed medicinal benefits. The Latin name Taraxacum originates in medieval Arabic writings on pharmacy. The scientist Al-Razi around 900 CE wrote "the tarashaquq is like chicory". The scientist and philosopher Ibn Sīnā around 1000 CE wrote a book chapter on Taraxacum . Gerard of Cremona , in translating Arabic to Latin around 1170, spelled it tarasacon . The English name, dandelion,

5123-458: The Earth's magnetic field . Broadly speaking, and with some exceptions, lithophile heavy metals can be extracted from their ores by electrical or chemical treatments , while chalcophile heavy metals are obtained by roasting their sulphide ores to yield the corresponding oxides, and then heating these to obtain the raw metals. Radium occurs in quantities too small to be economically mined and

5232-694: The Governor of N.S.W. , who was unwilling to recognize and allow the Indigenous people the right to use and control their own land as they saw fit - thus implementing the doctrine of terra nullius . In January 1844, the Wurundjeri-willam hosted an immense gathering of Indigenous people who came from all over central Victoria. An estimated 800 people journeyed to the district to witness important judicial proceedings carried out according to traditions of Aboriginal law . Since European settlement,

5341-460: The Pliocene of southern Belarus . Dandelions have been used by humans for food and as an herb for much of recorded history. They were well known to ancient Egyptians, Greeks and Romans, and are recorded to have been used in traditional Chinese medicine for over a thousand years. The plant was used as food and medicine by Native Americans . Dandelions were probably brought to North America on

5450-463: The hammer throw and shot put events are filled with lead in order to attain the minimum weight required under international rules. Tungsten was used in hammer throw balls at least up to 1980; the minimum size of the ball was increased in 1981 to eliminate the need for what was, at that time, an expensive metal (triple the cost of other hammers) not generally available in all countries. Tungsten hammers were so dense that they penetrated too deeply into

5559-476: The periodic table has an atomic number of 37 but a density of only 1.532 g/cm , which is below the threshold figure used by other authors. The same problem may occur with definitions which are based on atomic weight. Six elements near the end of periods (rows) 4 to 7 sometimes considered metalloids are treated here as metals: they are germanium (Ge), arsenic (As), selenium (Se), antimony (Sb), tellurium (Te), and astatine (At). Oganesson (Og)

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5668-467: The platinum group metals ( ruthenium , rhodium, palladium , osmium, iridium , and platinum), germanium, and tin—can be counted as siderophiles but only in terms of their primary occurrence in the Earth (core, mantle and crust), rather the crust. These metals otherwise occur in the crust, in small quantities, chiefly as chalcophiles (less so in their native form ). Concentrations of heavy metals below

5777-490: The vicinity of iron (in the periodic table) are largely made via stellar nucleosynthesis . In this process, lighter elements from hydrogen to silicon undergo successive fusion reactions inside stars, releasing light and heat and forming heavier elements with higher atomic numbers. Heavier heavy metals are not usually formed this way since fusion reactions involving such nuclei would consume rather than release energy. Rather, they are largely synthesised (from elements with

5886-424: The Merri with string bags suspended around their neck, searching the bottom of the stream for shellfish. Emu and kangaroo were hunted in the surrounding grasslands. In the forests and hills, possum was also a staple source of food and clothing, The flesh of the possum was cooked and eaten, while the skin was saved to be sewn into valuable waterproof cloaks. In May 1835, a historic meeting took place between Batman and

5995-478: The Wurundjeri-willam and other clans in which a document was signed that came to be called Batman's Treaty . To date, this remains the only treaty ever struck between European settlers and the Indigenous people of Australia. Batman wrote that these negotiations took place beside a "lovely stream of water" which historians now suspect to be the Merri Creek. This treaty was declared invalid by Sir Richard Bourke ,

6104-438: The abundance of the plant. Rabbits, wild turkeys, white-tailed deer, eastern chipmunks, bobwhite quail, and many species of birds will consume the seeds and foliage. Additionally, many insects will collect nectar from the flower, especially in early spring when there are very few other flowers in bloom. Taraxacum seeds are an important food source for certain birds (linnets, Linaria spp. ). Szabo studied nectar secretion in

6213-530: The aquatic environments of industrialised societies have been estimated to be two to three times those of pre-industrial levels. As a component of tetraethyl lead , (CH 3 CH 2 ) 4 Pb , it was used extensively in gasoline from the 1930s until the 1970s. Although the use of leaded gasoline was largely phased out in North America by 1996, soils next to roads built before this time retain high lead concentrations. Later research demonstrated

6322-424: The banks to take advantage of the improving environment, but the path is broken at Westgarth and North Fitzroy, necessitating traversing St George's Road. The CERES Community Environment Park - a community-run farming initiative with plenty of public spaces, cafes and markets - is a popular destination for Melburnians located adjacent to the Merri Creek. The Merri Creek Labyrinth, a circular labyrinth made of stone,

6431-419: The banks. Stormwater from suburban streets also drains directly into the creek, bringing rubbish and other pollutants. In recent decades, much has been done to remedy the creek's condition. As recently as the 1980s, the community considered Merri Creek little more than a weed-choked industrial drain. Things have improved significantly since then, largely thanks to the efforts of local community groups. Today it

6540-429: The basis of density, atomic number or chemical behaviour . More specific definitions have been published, none of which have been widely accepted. The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements ; only mercury , lead and bismuth meet all of them. Despite this lack of agreement, the term (plural or singular) is widely used in science. A density of more than 5 g/cm

6649-436: The behaviour of metal ions in inorganic systems. The system groups the elements by X m 2 r {\displaystyle X_{m}^{2}r} where X m {\displaystyle X_{m}} is the metal ion electronegativity and r {\displaystyle r} is its ionic radius . This index gauges the importance of covalent interactions vs ionic interactions for

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6758-474: The case of triploids , obligately) reproduce by apomixis , resulting in many local populations and endemism . In the British Isles alone, 234 microspecies (i.e. morphologically distinct clonal populations) are recognised in nine loosely defined sections, of which 40 are "probably endemic". A number of species of Taraxacum are seed-dispersed ruderals that rapidly colonize disturbed soil, especially

6867-440: The characteristics of heavier metals. Heavy metals are relatively rare in the Earth's crust but are present in many aspects of modern life. They are used in, for example, golf clubs , cars , antiseptics , self-cleaning ovens , plastics , solar panels , mobile phones , and particle accelerators . The International Union of Pure and Applied Chemistry (IUPAC), which standardizes nomenclature, says "the term heavy metals

6976-427: The common dandelion ( T. officinale ), which has been introduced over much of the temperate world. After flowering is finished, the dandelion flower head dries out for a day or two. The dried petals and stamens drop off, the bracts reflex (curve backwards), and the parachute ball opens into a full sphere. When development is complete, the mature seeds are attached to white, fluffy "parachutes" which easily detach from

7085-406: The creek's ecology. In the 1800s, John Batman described a “lovely stream of water” believed to be Merri Creek, but did not give it a name. It was known for a time as Lucy's Creek, apparently after Batman's daughter. A map dated to 1893 indicated a "Merri Merri Creek", which was shortened later to "Merri Creek." Some believe it means “very rocky” or “very stony” to symbolise the volcanic history of

7194-606: The creek. The large number of pre and post-contact archaeological sites demonstrate a heavy usage of the area by Indigenous Australians . The creek and surrounding valley was the site of many large gatherings of Aboriginal people and is thought to be the site of one of the earliest land treaties between Aboriginals and Europeans. Many archaeological sites found contain scattered stone artefacts from old campsites, and scarred trees from which traditional people removed slabs of bark to make canoes, containers and shields. The artefact scatters are found because erosion of some sort has exposed

7303-428: The crust are generally higher, with most being found in the largely iron-silicon-nickel core. Platinum , for example, comprises approximately 1 part per billion of the crust whereas its concentration in the core is thought to be nearly 6,000 times higher. Recent speculation suggests that uranium (and thorium) in the core may generate a substantial amount of the heat that drives plate tectonics and (ultimately) sustains

7412-583: The distinguishing criterion might be atomic number , or the chemical behaviour. Density criteria range from above 3.5 g/cm to above 7 g/cm . Atomic weight definitions can range from greater than sodium (atomic weight 22.98); greater than 40 (excluding s- and f-block metals, hence starting with scandium ); or more than 200, i.e. from mercury onwards. Atomic numbers are sometimes capped at 92 ( uranium ). Definitions based on atomic number have been criticised for including metals with low densities. For example, rubidium in group (column) 1 of

7521-442: The elements into nonmetals, light metals, and heavy metals. Light metals had densities of 0.860–5.0 g/cm ; heavy metals 5.308–22.000. The term heavy metal is sometimes used interchangeably with the term heavy element . For example, in discussing the history of nuclear chemistry , Magee notes that the actinides were once thought to represent a new heavy element transition group whereas Seaborg and co-workers "favoured ...

7630-635: The emblem of White Sulphur Springs, West Virginia . The citizens celebrate spring with an annual Dandelion Festival. The dandelion is the official flower of the University of Rochester in New York State , and "Dandelion Yellow" is one of the school's official colors. "The Dandelion Yellow" is an official University of Rochester song. The ability of dandelion seeds to travel as far as a kilometer in dry, windy and warm conditions, has been an inspiration for designing light-weight passive drones. In 2018, researchers discovered that dandelion seeds have

7739-964: The equivalent contemporary French pissenlit ) refers to the strong diuretic effect of the plant's roots. In various northeastern Italian dialects, the plant is known as pisacan (" dog pisses "), because they are found at the side of pavements. In Swedish , it is called maskros (worm rose) after the nymphs of small insects ( thrips larvae) usually present in the flowers. Raw dandelion greens contain high amounts of vitamins A , C , and K , and are moderate sources of calcium , potassium , iron , and manganese . Raw dandelion greens are 86% water, 9% carbohydrates , 3% protein , and 1% fat . A 100 gram ( 3 + 1 ⁄ 2 oz) reference amount supplies 45 Calories . The raw flowers contain diverse phytochemicals , including polyphenols , such as flavonoids apigenin , isoquercitrin (a quercetin -like compound), and caffeic acid , as well as terpenoids , triterpenes , and sesquiterpenes . The roots contain

7848-407: The following six categories. Some uses of heavy metals, including in sport, mechanical engineering , military ordnance , and nuclear science , take advantage of their relatively high densities. In underwater diving , lead is used as a ballast ; in handicap horse racing each horse must carry a specified lead weight, based on factors including past performance, so as to equalize the chances of

7957-493: The formation of coloured compounds; the capacity of most heavy metal ions (such as platinum, cerium or bismuth ) to exist in different oxidation states and are used in catalysts; strong exchange interactions in 3d or 4f orbitals (in iron, cobalt, and nickel, or the lanthanide heavy metals) that give rise to magnetic effects; and high atomic numbers and electron densities that underpin their nuclear science applications. Typical uses of heavy metals can be broadly grouped into

8066-407: The general characteristics of heavy metals such as density, strength, and durability. Other uses depend on the characteristics of the specific element, such as their biological role as nutrients or poisons or some other specific atomic properties. Examples of such atomic properties include: partly filled d- or f- orbitals (in many of the transition, lanthanide, and actinide heavy metals) that enable

8175-661: The general pattern that heavier elements tend to be less abundant and that scarcer elements are less likely to be nutritionally essential. In period 5 , molybdenum is required for the catalysis of redox reactions; cadmium is used by some marine diatoms for the same purpose; and tin may be required for growth in a few species. In period 6 , tungsten is required by some archaea and bacteria for metabolic processes . A deficiency of any of these period 4–6 essential heavy metals may increase susceptibility to heavy metal poisoning (conversely, an excess may also have adverse biological effects ). An average 70 kg human body

8284-450: The greatest potential to cause harm on account of their extensive use, the toxicity of some of their combined or elemental forms, and their widespread distribution in the environment. Hexavalent chromium , for example, is highly toxic as are mercury vapour and many mercury compounds. These five elements have a strong affinity for sulfur; in the human body they usually bind, via thiol groups (–SH), to enzymes responsible for controlling

8393-513: The implements which were covered with sediment. The scarred trees are often on the creek bank, fence line or road reserve where they escaped the clearance process. Both site types exhibit traces of the hunting and gathering lifestyle of pre-contact Victoria, and are a fragile and non-renewable historical resource. Aboriginal sites are protected under the Aboriginal Heritage Act 2006 . The northern suburbs of Melbourne are built on

8502-412: The industrial production of chlorine . Home electrical systems, for the most part, are wired with copper wire for its good conducting properties. Silver and gold are used in electrical and electronic devices, particularly in contact switches , as a result of their high electrical conductivity and capacity to resist or minimise the formation of impurities on their surfaces. Hafnium oxide , an insulator,

8611-449: The ingestion of germanium dietary supplements (~15 to 300 g in total consumed over a period of two months to three years). Exposure to osmium tetroxide (OsO 4 ) may cause permanent eye damage and can lead to respiratory failure and death. Indium salts are toxic if more than few milligrams are ingested and will affect the kidneys, liver, and heart. Cisplatin (PtCl 2 (NH 3 ) 2 ), an important drug used to kill cancer cells ,

8720-580: The lanthanides are also extensively employed in lasers. Gallium, indium, and arsenic; and copper, iridium, and platinum are used in LEDs (the latter three in organic LEDs ). Niche uses of heavy metals with high atomic numbers occur in diagnostic imaging , electron microscopy , and nuclear science. In diagnostic imaging, heavy metals such as cobalt or tungsten make up the anode materials found in x-ray tubes . In electron microscopy, heavy metals such as lead, gold, palladium, platinum, or uranium have been used in

8829-791: The latter case). Definition and usage Dandelion See text Taraxacum ( / t ə ˈ r æ k s ə k ə m / ) is a large genus of flowering plants in the family Asteraceae , which consists of species commonly known as dandelions . The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia but the two most commonplace species worldwide, T. officinale (the common dandelion) and T. erythrospermum (the red-seeded dandelion), were introduced from Europe into North America, where they are an invasive species. Dandelions thrive in temperate regions and can be found in yards, gardens, sides of roads, among crops, and in many other habitats. Both species are edible in their entirety and have

8938-409: The leaves are 50–250 mm (2–10 in) long or longer, simple, lobed-to-pinnatisect, and form a basal rosette above the central taproot. The flower heads are yellow to orange coloured, and are open in the daytime, but closed at night. The heads are borne singly on a hollow stem ( scape ) that is usually leafless and rises 10–100 mm ( 3 ⁄ 8 – 3 + 7 ⁄ 8  in) or more above

9047-503: The leaves, stems, flowers, and roots, is edible and nutritious, with nutrients such as vitamins A and K as well as calcium and iron. Dandelions are found on six continents and have been gathered for food since prehistory, but the varieties commercially cultivated for consumption are mainly native to Eurasia and North America . A perennial plant , its leaves grow back if the taproot is left intact. To make leaves more palatable, they are often blanched to remove bitterness, or sauteed in

9156-474: The leaves. Stems and leaves exude a white, milky latex when broken. A rosette may produce several flowering stems at a time. The flower heads are 20–50 mm ( 3 ⁄ 4 –2 in) in diameter and consist entirely of ray florets . The flower heads mature into spherical seed heads sometimes called blowballs or clocks (in both British and American English) containing many single-seeded fruits called cypselae , similar to achenes . Each cypsela

9265-421: The lithophiles. In contrast, gold is a siderophile , or iron-loving element. It does not readily form compounds with either oxygen or sulfur. At the time of the Earth's formation , and as the most noble (inert) of metals, gold sank into the core due to its tendency to form high-density metallic alloys. Consequently, it is a relatively rare metal. Some other (less) noble heavy metals—molybdenum, rhenium ,

9374-414: The lower reaches of the creek have been significantly degraded by human activity. In the early history of Melbourne, numerous quarries were established along the creek to extract bluestone for the construction of many of the city's buildings and paving for roads and lanes. These quarries were later used as landfill for waste. Numerous environmental weeds, such as prickly pear and weeping willows , invaded

9483-601: The manufacture of tools, machinery, appliances , utensils, pipes, railroad tracks , buildings and bridges, automobiles, locks, furniture, ships, planes, coinage and jewellery. They are also used as alloying additives for enhancing the properties of other metals. Of the two dozen elements that have been used in the world's monetised coinage only two, carbon and aluminium, are not heavy metals. Gold, silver, and platinum are used in jewellery as are, for example, nickel, copper, indium, and cobalt in coloured gold . Low-cost jewellery and children's toys may be made, to

9592-406: The many sites of geological interest along the Merri valley is the rocky cliff face on the eastern side of Merri Creek visible from the shared path in Clifton Hill. Its tall, cracked (or jointed) basalt columns, formed by cooling lava, are clearly visible and the weathering evident in the rocky riffles midstream where columns have collapsed and tumbled into the stream. Some of the vertical fractures at

9701-508: The metals involved are not always consistently defined. As well as being relatively dense, heavy metals tend to be less reactive than lighter metals and have far fewer soluble sulfides and hydroxides . While it is relatively easy to distinguish a heavy metal such as tungsten from a lighter metal such as sodium , a few heavy metals, such as zinc, mercury, and lead, have some of the characteristics of lighter metals; and lighter metals such as beryllium , scandium , and titanium, have some of

9810-407: The next two elements, polonium and astatine, which decay to bismuth or lead. The r-process is so fast it can skip this zone of instability and go on to create heavier elements such as thorium and uranium. Heavy metals condense in planets as a result of stellar evolution and destruction processes. Stars lose much of their mass when it is ejected late in their lifetimes, and sometimes thereafter as

9919-426: The other 95% of the crust. Despite their overall scarcity, heavy metals can become concentrated in economically extractable quantities as a result of mountain building , erosion , or other geological processes . Heavy metals are found primarily as lithophiles (rock-loving) or chalcophiles (ore-loving). Lithophile heavy metals are mainly f-block elements and the more reactive of the d-block elements. They have

10028-506: The past to make conductive coatings and to introduce electron density into biological specimens by staining , negative staining , or vacuum deposition . In nuclear science, nuclei of heavy metals such as chromium, iron, or zinc are sometimes fired at other heavy metal targets to produce superheavy elements ; heavy metals are also employed as spallation targets for the production of neutrons or isotopes of non-primordial elements such as astatine (using lead, bismuth, thorium, or uranium in

10137-599: The plume of seeds to close up and reduce the chance to separate from the stem, waiting for optimal conditions that will maximize dispersal and germination. Many similar plants in the family Asteraceae with yellow flowers are sometimes known as false dandelions . Dandelion flowers are very similar to those of cat's ears ( Hypochaeris ). Both plants carry similar flowers, which form into windborne seeds. However, dandelion flowers are borne singly on unbranched, hairless and leafless, hollow stems, while cat's ear flowering stems are branched, solid, and carry bracts. Both plants have

10246-525: The point where there is insufficient food. However, the first platypus sighting in decades occurred between Thornbury and Coburg in September 2010. Platypus sightings have continued, albeit on a "few and far between" basis, ever since. Parks Victoria manages some of the established parklands on the banks of Merri Creek. Facilities include football and cricket ovals, tennis courts and playgrounds. The Merri Creek Trail shared pathway has been established along

10355-556: The risk is mild. Latex containing sesquiterpene lactones are present in high concentrations in the main root and stems of the common dandelion. However, only a few researchers have mentioned the possible risk of mild allergic contact dermatitis for people with lactone hypersensitivity . Dandelion has been used in traditional medicine in Europe, North America, and China. Dandelions do not depend on wildlife for distribution or pollination; however much of wildlife benefits from

10464-461: The same way as spinach . Dandelion greens have been a part of traditional Kashmiri cuisine , Lebanese cuisine , Spanish cuisine , Italian cuisine , Albanian cuisine , Slovenian , Sephardic Jewish , Chinese , Greek cuisine ( χόρτα ) and Korean cuisines . In Crete , the leaves of a variety called 'Mari' ( Μαρί ), 'Mariaki' ( Μαριάκι ), or 'Koproradiko' ( Κοπροράδικο ) are eaten by locals, either raw or boiled, in salads. T. megalorhizon ,

10573-495: The sections Palustria and Spectabilia . Between the pappus and the achene is a stalk called a beak, which elongates as the fruit matures. The beak breaks off from the achene quite easily, separating the seed from the parachute. The species of Taraxacum are tap-rooted , perennial , herbaceous plants, native to temperate areas of the Northern Hemisphere. The genus contains many species, which usually (or in

10682-407: The seedhead and glide by wind, dispersing. The seeds are able to cover large distances when dispersed due to the unique morphology of the pappus which works to create a unique type of vortex ring that stays attached to the seed rather than being sent downstream. In addition to the creation of this vortex ring, the pappus can adjust its morphology depending on the moisture in the air. This allows

10791-690: The site. The phrase is said to originate from the Woiwurrung language , but its authenticity is disputed by historians and Indigenous Elders. Over 400 million years ago. the sea covering the area receded, leaving behind a layer of yellowish marine siltstone and sandstone rocks. Around 66 million years ago, non-marine sediments left a sandy layer behind. Over time, the ancestral valley of the Merri Creek developed, eroding through these sediments. Then, from 4.6 to 0.8 million years ago, volcanoes such as Hayes Hill (about 5 km east of Donnybrook ) and Mount Fraser (near Beveridge ) erupted, sending lava on

10900-464: The species T. officinale is listed as a noxious weed . It can also be considered invasive in protected areas such as national parks . For example, Denali National Park and Preserve in Alaska lists Taraxacum officinale as the most common invasive species in the park and hosts an annual "Dandelion Demolition" event where volunteers are trained to remove the plant from the park's roadsides. With

11009-404: The speed of metabolic reactions. The resulting sulfur-metal bonds inhibit the proper functioning of the enzymes involved; human health deteriorates, sometimes fatally. Chromium (in its hexavalent form) and arsenic are carcinogens ; cadmium causes a degenerative bone disease ; and mercury and lead damage the central nervous system . Lead is the most prevalent heavy metal contaminant. Levels in

11118-506: The strongest type of permanent magnet commercially available. They are key components of, for example, car door locks, starter motors , fuel pumps , and power windows . Heavy metals are used in lighting , lasers , and light-emitting diodes (LEDs). Flat panel displays incorporate a thin film of electrically conducting indium tin oxide . Fluorescent lighting relies on mercury vapour for its operation. Ruby lasers generate deep red beams by exciting chromium atoms in aluminum oxide ;

11227-455: The top of the cliff appear to be leaning, forming a striking radial pattern. As native vegetation has been regenerated, some species of native wildlife have returned to the creek. These include kookaburras , kingfishers , yellow-tailed Black Cockatoos , echdidnas and frogs . There have also been reports of platypuses in the upper northern regions and further south in Coburg. Merri Creek

11336-701: The turf. The higher the projectile density, the more effectively it can penetrate heavy armor plate ... Os , Ir , Pt , and Re  ... are expensive ... U offers an appealing combination of high density, reasonable cost and high fracture toughness. AM Russell and KL Lee Structure–property relations in nonferrous metals (2005, p. 16) Heavy metals are used for ballast in boats, aeroplanes, and motor vehicles; or in balance weights on wheels and crankshafts , gyroscopes , and propellers , and centrifugal clutches , in situations requiring maximum weight in minimum space (for example in watch movements ). In military ordnance, tungsten or uranium

11445-608: The unceded land of the Wurundjeri-willam people. During the first years of European colonisation, the Wurundjeri were represented by influential senior men such as Billibellary . His clan lived on the northern bank of the Yarra and their territory extended from Yarra Bend northwards along the Merri Creek. The creek supplied the Wurundjeri-willam with an abundance of food such as eel, fish, and duck. Women waded through

11554-458: The various competitors. In golf , tungsten, brass , or copper inserts in fairway clubs and irons lower the centre of gravity of the club making it easier to get the ball into the air; and golf balls with tungsten cores are claimed to have better flight characteristics. In fly fishing , sinking fly lines have a PVC coating embedded with tungsten powder, so that they sink at the required rate. In track and field sport, steel balls used in

11663-741: The walls of such ovens helps oxidise carbon -based cooking residues). In soap chemistry, heavy metals form insoluble soaps that are used in lubricating greases , paint dryers, and fungicides (apart from lithium, the alkali metals and the ammonium ion form soluble soaps). The colours of glass , ceramic glazes , paints , pigments , and plastics are commonly produced by the inclusion of heavy metals (or their compounds) such as chromium, manganese, cobalt, copper, zinc, zirconium , molybdenum, silver, tin, praseodymium , neodymium , erbium , tungsten, iridium, gold, lead, or uranium. Tattoo inks may contain heavy metals, such as chromium, cobalt, nickel, and copper. The high reflectivity of some heavy metals

11772-605: The world's oceans. Recent examples of heavy metal contamination and health risks include the occurrence of Minamata disease , in Japan (1932–1968; lawsuits ongoing as of 2016); the Bento Rodrigues dam disaster in Brazil, high levels of lead in drinking water supplied to the residents of Flint , Michigan, in the north-east of the United States and 2015 Hong Kong heavy metal in drinking water incidents . Heavy metals up to

11881-531: Was also commonly used to make the traditional British soft drink dandelion and burdock , and is one of the ingredients of root beer . Dandelions were once considered delicacies by the Victorian gentry, who used them mostly in salads and sandwiches. The yellow flowers can be dried and ground into a yellow-pigmented powder and used as a dye . Dandelions may cause allergic reactions for sensitive individuals when consumed or coming into contact with skin, but

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