Pesticides are substances that are meant to control pests, including weeds. The term pesticide includes all of the following: herbicide, insecticides nematicide, piscicide, rodenticide, insect repellent, animal repellent and fungicide; the most common of these are herbicides which account for 80% of all pesticide use. Most pesticides are intended to serve as plant protection products, which in general, protect plants from weeds, fungi, or insects. In general, a pesticide is a chemical or biological agent that deters, kills, or otherwise discourages pests. Target pests can include insects, plant pathogens, molluscs, mammals, fish and microbes that destroy property, cause nuisance, or spread disease, or are disease vectors. Along with these benefits, pesticides have drawbacks, such as potential toxicity to humans and other species; the Food and Agriculture Organization has defined pesticide as: any substance or mixture of substances intended for preventing, destroying, or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals, causing harm during or otherwise interfering with the production, storage, transport, or marketing of food, agricultural commodities and wood products or animal feedstuffs, or substances that may be administered to animals for the control of insects, arachnids, or other pests in or on their bodies.
The term includes substances intended for use as a plant growth regulator, desiccant, or agent for thinning fruit or preventing the premature fall of fruit. Used as substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport. Pesticides can be classified by target organism, chemical structure, physical state. Biopesticides include biochemical pesticides. Plant-derived pesticides, or "botanicals", have been developing quickly; these include the pyrethroids, nicotinoids, a fourth group that includes strychnine and scilliroside. Many pesticides can be grouped into chemical families. Prominent insecticide families include organochlorines and carbamates. Organochlorine hydrocarbons could be separated into dichlorodiphenylethanes, cyclodiene compounds, other related compounds, they operate by disrupting the sodium/potassium balance of the nerve fiber, forcing the nerve to transmit continuously. Their toxicities vary but they have been phased out because of their persistence and potential to bioaccumulate.
Organophosphate and carbamates replaced organochlorines. Both operate through inhibiting the enzyme acetylcholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely and causing a variety of symptoms such as weakness or paralysis. Organophosphates are quite toxic to vertebrates and have in some cases been replaced by less toxic carbamates. Thiocarbamate and dithiocarbamates are subclasses of carbamates. Prominent families of herbicides include phenoxy and benzoic acid herbicides, triazines and Chloroacetanilides. Phenoxy compounds tend to selectively kill broad-leaf weeds rather than grasses; the phenoxy and benzoic acid herbicides function similar to plant growth hormones, grow cells without normal cell division, crushing the plant's nutrient transport system. Triazines interfere with photosynthesis. Many used pesticides are not included in these families, including glyphosate; the application of pest control agents is carried out by dispersing the chemical in a solvent-surfactant system to give a homogeneous preparation.
A virus lethality study performed in 1977 demonstrated that a particular pesticide did not increase the lethality of the virus, however combinations which included some surfactants and the solvent showed that pretreatment with them markedly increased the viral lethality in the test mice. Pesticides can be classified based upon their biological mechanism application method. Most pesticides work by poisoning pests. A systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is upward and outward. Increased efficiency may be a result. Systemic insecticides, which poison pollen and nectar in the flowers, may kill bees and other needed pollinators. In 2010, the development of a new class of fungicides called; these work by taking advantage of natural defense chemicals released by plants called phytoalexins, which fungi detoxify using enzymes. The paldoxins inhibit the fungi's detoxification enzymes, they are believed to be greener.
Since before 2000 BC, humans have utilized pesticides to protect their crops. The first known pesticide was elemental sulfur dusting used in ancient Sumer about 4,500 years ago in ancient Mesopotamia; the Rig Veda, about 4,000 years old, mentions the use of poisonous plants for pest control. By the 15th century, toxic chemicals such as arsenic and lead were being applied to crops to kill pests. In the 17th century, nicotine sulfate was extracted from tobacco leaves for use as an insecticide; the 19th century saw the introduction of two more natural pesticides, derived fr
Logwood redirects here. It may refer to members of the genus Xylosma, part of the willow family, Salicaceae. Haematoxylum campechianum is a species of flowering tree in the legume family, native to southern Mexico and northern Central America; the tree was of great economic importance from the 17th century to the 19th century, when it was logged and exported to Europe for use in dyeing fabrics. The modern nation of Belize developed from 17th- and 18th-century logging camps established by the English; the tree's scientific name means "bloodwood". Logwood was used for a long time as a natural source of dye. Logwood chips are still used as an important source of haematoxylin, used in histology for staining; the bark and leaves are used in various medical applications. In its time, logwood was considered a versatile dye, was used on textiles and for paper; the extract was once used as a pH indicator. Brownish when neutral, it purple when alkaline. In a small demonstrative experiment, if two drops, one of concentrated ammonia and one of logwood extract, are placed close enough, the NH3 vapours will change the color of the extract to a purple shade.
Logwood played an important role in the lives of 17th-century buccaneers and into the Golden Age of Piracy. Spain claimed all of Central and South America as its sovereign territory through the 17th and 18th centuries. Spain periodically sent privateers to capture the logwood cutters – for example, Juan Corso's 1680 cruise – sometimes in retaliation for buccaneer raids on Spanish cities. Logwood cutters, now out of work joined onto pirate and buccaneer crews to raid the Spanish in return, as Edmund Cooke did after losing two logwood-hauling ships to the Spanish; when Spanish forces ejected a great many logwood cutters in 1715, they flocked to Nassau and swelled the already-considerable numbers of pirates gathering there. By the mid-1720s logwood cutters had themselves become targets of pirates such Francis Spriggs, Edward Low, George Lowther. Logwood cutting was profitable – "According to a government report, in the four years 1713 to 1716, some 4,965 tons of logwood were exported to England at not less than £60,000 per annum" – but only brought in a fraction of the profits from tobacco and other legal exports, "was always a minor industry carried on by a few hundred ex-seamen and pirates in a remote corner of the globe".
Wayne's Word: "Logwood and Brazilwood, Trees That Spawned 2 Nations" Media related to Haematoxylum campechianum at Wikimedia Commons Data related to Haematoxylum campechianum at Wikispecies
Water quality refers to the chemical, physical and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose, it is most used by reference to a set of standards against which compliance achieved through treatment of the water, can be assessed. The most common standards used to assess water quality relate to health of ecosystems, safety of human contact, drinking water. In the setting of standards, agencies make political and technical/scientific decisions about how the water will be used. In the case of natural water bodies, they make some reasonable estimate of pristine conditions. Natural water bodies will vary in response to environmental conditions. Environmental scientists work to understand how these systems function, which in turn helps to identify the sources and fates of contaminants. Environmental lawyers and policymakers work to define legislation with the intention that water is maintained at an appropriate quality for its identified use.
The vast majority of surface water on the Earth is neither toxic. This remains true. Another general perception of water quality is that of a simple property that tells whether water is polluted or not. In fact, water quality is a complex subject, in part because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial and commercial activities are a major cause of water pollution as are runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage; the parameters for water quality are determined by the intended use. Work in the area of water quality tends to be focused on water, treated for human consumption, industrial use, or in the environment. Contaminants that may be in untreated water include microorganisms such as viruses and bacteria. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a heat sink, overuse; the United States Environmental Protection Agency limits the amounts of certain contaminants in tap water provided by US public water systems.
The Safe Drinking Water Act authorizes EPA to issue two types of standards: primary standards regulate substances that affect human health. The U. S. Food and Drug Administration regulations establish limits for contaminants in bottled water that must provide the same protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants; the presence of these contaminants does not indicate that the water poses a health risk. In urbanized areas around the world, water purification technology is used in municipal water systems to remove contaminants from the source water before it is distributed to homes, businesses and other recipients. Water drawn directly from a stream, lake, or aquifer and that has no treatment will be of uncertain quality. Dissolved minerals may affect suitability of water for a range of domestic purposes; the most familiar of these is the presence of ions of calcium and magnesium which interfere with the cleaning action of soap, can form hard sulfate and soft carbonate deposits in water heaters or boilers.
Hard water may be softened to remove these ions. The softening process substitutes sodium cations. Hard water may be preferable to soft water for human consumption, since health problems have been associated with excess sodium and with calcium and magnesium deficiencies. Softening may increase cleaning effectiveness. Various industries' wastes and effluents can pollute the water quality in receiving bodies of water. Environmental water quality called ambient water quality, relates to water bodies such as lakes and oceans. Water quality standards for surface waters vary due to different environmental conditions and intended human uses. Toxic substances and high populations of certain microorganisms can present a health hazard for non-drinking purposes such as irrigation, fishing, rafting and industrial uses; these conditions may affect wildlife, which use the water for drinking or as a habitat. Modern water quality laws specify protection of fisheries and recreational use and require, as a minimum, retention of current quality standards.
There is some desire among the public to return water bodies to pristine, or pre-industrial conditions. Most current environmental laws focus on the designation of particular uses of a water body. In some countries these designations allow for some water contamination as long as the particular type of contamination is not harmful to the designated uses. Given the landscape changes in the watersheds of many freshwater bodies, returning to pristine conditions would be a significant challenge. In these cases, environmental scientists focus on achieving goals for maintaining healthy ecosystems and may concentrate on the protection of populations of endangered species and protecting human health; the complexity of water quality as a subject is reflected in the many types of measu
Deforestation, clearcutting or clearing is the removal of a forest or stand of trees from land, converted to a non-forest use. Deforestation can involve conversion of forest land to ranches, or urban use; the most concentrated deforestation occurs in tropical rainforests. About 31% of Earth's land surface is covered by forests. Deforestation can occur for several reasons: trees can be cut down to be used for building or sold as fuel, while cleared land can be used as pasture for livestock and plantation; the removal of trees without sufficient reforestation has resulted in habitat damage, biodiversity loss, aridity. It has adverse impacts on biosequestration of atmospheric carbon dioxide. Deforestation has been used in war to deprive the enemy of vital resources and cover for its forces. Modern examples of this were the use of Agent Orange by the British military in Malaya during the Malayan Emergency and by the United States military in Vietnam during the Vietnam War; as of 2005, net deforestation rates had ceased to increase in countries with a per capita GDP of at least US$4,600.
Deforested regions incur significant adverse soil erosion and degrade into wasteland. Disregard of ascribed value, lax forest management, deficient environmental laws are some of the factors that lead to large-scale deforestation. In many countries, deforestation–both occurring and human-induced–is an ongoing issue. Deforestation causes extinction, changes to climatic conditions and displacement of populations, as observed by current conditions and in the past through the fossil record. More than half of all plant and land animal species in the world live in tropical forests. Between 2000 and 2012, 2.3 million square kilometres of forests around the world were cut down. As a result of deforestation, only 6.2 million square kilometres remain of the original 16 million square kilometres of tropical rainforest that covered the Earth. An area the size of a football pitch is cleared from the Amazon rainforest every minute, with 136 million acres of rainforest cleared for animal agriculture overall.
According to the United Nations Framework Convention on Climate Change secretariat, the overwhelming direct cause of deforestation is agriculture. Subsistence farming is responsible for 48% of deforestation. Experts do not agree on whether industrial logging is an important contributor to global deforestation; some argue that poor people are more to clear forest because they have no alternatives, others that the poor lack the ability to pay for the materials and labour needed to clear forest. One study found that population increases due to high fertility rates were a primary driver of tropical deforestation in only 8% of cases. Other causes of contemporary deforestation may include corruption of government institutions, the inequitable distribution of wealth and power, population growth and overpopulation, urbanization. Globalization is viewed as another root cause of deforestation, though there are cases in which the impacts of globalization have promoted localized forest recovery. In 2000 the United Nations Food and Agriculture Organization found that "the role of population dynamics in a local setting may vary from decisive to negligible", that deforestation can result from "a combination of population pressure and stagnating economic and technological conditions".
The degradation of forest ecosystems has been traced to economic incentives that make forest conversion appear more profitable than forest conservation. Many important forest functions have no markets, hence, no economic value, apparent to the forests' owners or the communities that rely on forests for their well-being. From the perspective of the developing world, the benefits of forest as carbon sinks or biodiversity reserves go to richer developed nations and there is insufficient compensation for these services. Developing countries feel that some countries in the developed world, such as the United States of America, cut down their forests centuries ago and benefited economically from this deforestation, that it is hypocritical to deny developing countries the same opportunities, i.e. that the poor shouldn't have to bear the cost of preservation when the rich created the problem. Some commentators have noted a shift in the drivers of deforestation over the past 30 years. Whereas deforestation was driven by subsistence activities and government-sponsored development projects like transmigration in countries like Indonesia and colonization in Latin America, Java, so on, during the late 19th century and the earlier half of the 20th century, by the 1990s the majority of deforestation was caused by industrial factors, including extractive industries, large-scale cattle ranching, extensive agriculture.
Since 2001, commodity-driven deforestation, more to be permanent, has accounted for about a quarter of all forest disturbance, this loss has been concentrated in South America and Southeast Asia. Deforestation is shaping climate and geography. Deforestation is a contributor to global warming, is cited as one of the major causes of the enhanced greenhouse effect. Tropical deforestation is responsible for 20% of world greenhouse gas emissions. According to the Intergovernmental Panel on Climate Change deforestation in tropical areas, could account for up to one-third of total anthropogenic carbon d
Spaniards, or the Spanish people, are a Romance ethnic group that are indigenous to Spain. They share a common Spanish culture, history and language. Within Spain, there are a number of nationalisms and regionalisms, reflecting the country's complex history and diverse culture. Although the official language of Spain is known as "Spanish", it is only one of the national languages of Spain, is less ambiguously known as Castilian, a standard language based on the medieval romance speech of the Kingdom of Castile in north and central Spain; the Spanish people's heritage includes the pre-Celts and Celts. There are several spoken regional languages, most notably Basque and Galician. There are many populations outside Spain with ancestors who emigrated from Spain and who share a Hispanic culture; the Roman Republic conquered Iberia during the 2nd and 1st centuries BC. As a result of Roman colonization, the majority of local languages, with the exception of Basque, stem from the Vulgar Latin; the Germanic Vandals and Suebi, with part of the Iranian Alans under King Respendial conquered the peninsula in 409 AD.
In turn, the Visigoths established themselves in Spain. The Iberian Peninsula was conquered and brought under the rule of the Arab Umayyads in 711 and by the Berber North African dynasties the Almohads and the Almoravids in the 11th and 12th centuries. Following the eight century Christian Reconquista against the Moors, the modern Spanish state was formed with the union of the Kingdoms of Castille and Aragon, the conquest of the last Muslim Nasrid Kingdom of Granada and the Canary Islands in the late 15th century. In the early 16th century the Kingdom of Navarre was conquered; as Spain expanded its empire in the Americas, religious minorities in Spain such as Jews and Muslims were either converted or expelled and the Catholic church fiercely persecuted heresy during a period known as the Spanish Inquisition. A small number of Spaniards descend from converted Jewish and North Africans, as a result of the 800 years of Moorish occupation of the Iberian Peninsula. In parallel, a wave of emigration to the Americas began, with over 1.86 million Spaniards emigrating to the Spanish Americas during the colonial period and the population of the Spanish Empire had risen to 16.8 million by the end of the 18th century In the post-colonial period, a further 3.5 million Spanish left for the Americas Argentina, Mexico, Chile, Puerto Rico and Cuba.
Spain is home to one of the largest communities of Romani people. The Government's statistical agency CIS estimated in 2007 that the number of Gitanos present in Spain is around one million; the Spanish Roma, which belong to the Iberian Kale subgroup, are a formerly-nomadic community, which spread across Western Asia, North Africa, Europe, first reaching Spain in the 15th century. The population of Spain is becoming diverse due to recent immigration. From 2000 to 2010, Spain had among the highest per capita immigration rates in the world and the second highest absolute net migration in the World and immigrants now make up about 10% of the population; the prolonged economic crisis between 2008 and 2015 reduced both immigration rates and the total number of foreigners in the country, Spain becoming once more a net emigrant country. The earliest modern humans inhabiting Spain are believed to have been Neolithic peoples who may have arrived in the Iberian Peninsula as early as 35,000–40,000 years ago.
In more recent times the Iberians are believed to have arrived or developed in the region between the 4th millennium BC and the 3rd millennium BC settling along the Mediterranean coast. Celts settled in Spain during the Iron Age; some of those tribes in North-central Spain, which had cultural contact with the Iberians, are called Celtiberians. In addition, a group known as the Tartessians and Turdetanians inhabited southwestern Spain and who are believed to have developed a separate civilization of Phoenician influence; the seafaring Phoenicians and Carthaginians successively founded trading colonies along the Mediterranean coast over a period of several centuries. The Second Punic War between the Carthaginians and Romans was fought in what is now Spain and Portugal; the Roman Republic conquered Iberia during the 2nd and 1st centuries BC transformed most of the region into a series of Latin-speaking provinces. As a result of Roman colonization, the majority of local languages, with the exception of Basque, stem from the Vulgar Latin, spoken in Hispania, which evolved into the modern languages of the Iberian Peninsula, including Castilian, which became the main lingua franca of Spain, is now known in most countries as Spanish.
Hispania emerged as an important part of the Roman Empire and produced notable historical figures such as Trajan, Hadrian and Quintilian. The Germanic Vandals and Suebi, with part of the Iranian Alans under King Respendial, arrived in the peninsula in 409 AD. Part of the Vandals with the remaining Alans, now under Geiseric in personal union removed themselves to North Africa after a few conflicts with another Germanic tribe, the Visigoths, who established in Toulouse supported Roman campaigns against the Vandals and Alans in 415–19 AD and became the dominant power in Iberia for three centuries; the Visigoths were romanized in the eastern Empire and Christians, so their integration withi
The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and south west, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, to the south by the north coast of South America; the entire area of the Caribbean Sea, the numerous islands of the West Indies, adjacent coasts, are collectively known as the Caribbean. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2; the sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria and Gulf of Honduras; the Caribbean Sea has the Mesoamerican Barrier Reef. It runs 1,000 km along the coasts of Mexico, Belize and Honduras; the name "Caribbean" derives from the Caribs, one of the region's dominant Native American groups at the time of European contact during the late 15th century.
After Christopher Columbus landed in the Bahamas in 1492, the Spanish term Antillas applied to the lands. During the first century of development, Spanish dominance in the region remained undisputed. From the 16th century, Europeans visiting the Caribbean region identified the "South Sea" as opposed to the "North Sea"; the Caribbean Sea had been unknown to the populations of Eurasia until 1492, when Christopher Columbus sailed into Caribbean waters on a quest to find a sea route to Asia. At that time the Western Hemisphere in general was unknown to most Europeans, although it had been discovered between the years 800 and 1000 by the vikings. Following the discovery of the islands by Columbus, the area was colonized by several Western cultures. Following the colonization of the Caribbean islands, the Caribbean Sea became a busy area for European-based marine trading and transports, this commerce attracted pirates such as Samuel Bellamy and Blackbeard; as of 2015 the area is home to borders 12 continental countries.
The International Hydrographic Organization defines the limits of the Caribbean Sea as follows: On the North. In the Windward Channel – a line joining Caleta Point and Pearl Point in Haïti. In the Mona Passage – a line joining Cape Engaño and the extreme of Agujereada in Puerto Rico. Eastern limits. From Point San Diego Northward along the meridian thereof to the 100-fathom line, thence Eastward and Southward, in such a manner that all islands and narrow waters of the Lesser Antilles are included in the Caribbean Sea as far as Galera Point. From Galera Point through Trinidad to Galeota Point and thence to Baja Point in Venezuela. Note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea; the Caribbean Sea is an oceanic sea situated on the Caribbean Plate. The Caribbean Sea is separated from the ocean by several island arcs of various ages; the youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad and Tobago off the coast of Venezuela.
This arc was formed by the collision of the South American Plate with the Caribbean Plate and includes active and extinct volcanoes such as Mount Pelee, the Quill on Sint Eustatius in the Caribbean Netherlands and Morne Trois Pitons on Dominica. The larger islands in the northern part of the sea Cuba, Hispaniola and Puerto Rico lie on an older island arc; the geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a horizontal fracture that split the supercontinent called Pangea in the Mesozoic Era. It is assumed the proto-caribbean basin existed in the Devonian period. In the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size; the next stage of the Caribbean Sea's formation began in the Triassic. Powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool.
The emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these basins marked the beginning of the Atlantic Ocean and contributed to the destruction of Pangaea at the end of the late Jurassic. During the Cretaceous the Caribbean acquired the shape close to that seen today. In the early Paleogene due to Marine regression the Caribbean became separated from the Gulf of Mexico and the Atlantic Ocean by the land of Cuba and Haiti; the Caribbean remained like this for most of the Cenozoic until the Holocene when rising water levels of the oceans restored communication with the Atlantic Ocean. The Caribbean's floor is composed of sub-oceanic sediments of deep red clay in the deep basins and troughs. On continental slopes and ridges calcareous silts are found. Clay minerals having been deposited by the mainland river Orinoco and the Magdalena River. Deposits on th