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53-470: Gokyo Lakes are oligotrophic lakes in Nepal 's Sagarmatha National Park , located at an elevation of 4,700–5,000 m (15,400–16,400 ft). They were named after Gokyo Ri peak. These lakes are the world's highest freshwater lake system comprising six main lakes, of which Thonak Lake is the largest. In September 2007, Gokyo and its associated wetlands of 7,770 ha (77.7 km) have been designated

106-491: A or b . Since chlorophyllide a can be converted to chlorophyllide b and the latter can be re-esterified to chlorophyll b , these processes allow cycling between chlorophylls a and b . Moreover, chlorophyll b can be directly reduced (via 7 -hydroxychlorophyll a ) back to chlorophyll a , completing the cycle. In later stages of senescence, chlorophyllides are converted to a group of colourless tetrapyrroles known as nonfluorescent chlorophyll catabolites (NCC's) with

159-564: A Ramsar site . Gokyo Lakes are located in the Khumjung Village Development Committee of Solukhumbu District in the Sagarmatha Zone in north-eastern Nepal . Gokyo Cho, also called Dudh Pokhari, is the main lake with an area of 42.9 ha (106 acres), and the village of Gokyo lies on its eastern shore. Thonak Cho is the largest lake with an area of 65.07 ha (160.8 acres). Gyazumpa Cho

212-728: A are at 465 nm and 665 nm. Chlorophyll a fluoresces at 673 nm (maximum) and 726 nm. The peak molar absorption coefficient of chlorophyll a exceeds 10  M  cm , which is among the highest for small-molecule organic compounds. In 90% acetone-water, the peak absorption wavelengths of chlorophyll a are 430 nm and 664 nm; peaks for chlorophyll b are 460 nm and 647 nm; peaks for chlorophyll c 1 are 442 nm and 630 nm; peaks for chlorophyll c 2 are 444 nm and 630 nm; peaks for chlorophyll d are 401 nm, 455 nm and 696 nm. Ratio fluorescence emission can be used to measure chlorophyll content. By exciting chlorophyll

265-419: A fluorescence at a lower wavelength, the ratio of chlorophyll fluorescence emission at 705 ± 10 nm and 735 ± 10 nm can provide a linear relationship of chlorophyll content when compared with chemical testing. The ratio F 735 / F 700 provided a correlation value of r 0.96 compared with chemical testing in the range from 41 mg m up to 675 mg m . Gitelson also developed

318-409: A considerable difference in the absorption spectrum, allowing plants to absorb a greater portion of visible light. The structures of chlorophylls are summarized below: Chlorophyll e is reserved for a pigment that has been extracted from algae in 1966 but not chemically described. Besides the lettered chlorophylls, a wide variety of sidechain modifications to the chlorophyll structures are known in

371-473: A formula for direct readout of chlorophyll content in mg m . The formula provided a reliable method of measuring chlorophyll content from 41 mg m up to 675 mg m with a correlation r value of 0.95. The Dualex is an optical sensor used in plant science and agriculture for the assessment of chlorophyll contents in leaves. This device allows researchers to perform real-time and non-destructive measurements. In some plants, chlorophyll

424-416: A given light intensity is small. Thus, the other chlorophylls in the photosystem and antenna pigment proteins all cooperatively absorb and funnel light energy to the reaction center. Besides chlorophyll  a , there are other pigments, called accessory pigments , which occur in these pigment–protein antenna complexes. Several chlorophylls are known. All are defined as derivatives of the parent chlorin by

477-457: A holomictic lake, during the fall, the cooling of the epilimnion reduces lake stratification, thereby allowing for mixing to occur. Winds aid in this process. Thus it is the deep mixing of lakes (which occurs most often during the fall and early winter, in holomictic lakes of the monomictic subtype) that allows oxygen to be transported from the epilimnion to the hypolimnion. In this way, oligotrophic lakes can have significant oxygen down to

530-657: A holy bath in the lakes during the Janai Purnima festival , which usually occurs in the month of August. On an average 7,000 tourists annually visit the Gokyo Lakes. The site is worshipped as the residing place of 'Nag Devata' (Snake God); a temple of the Hindu deities Vishnu and Shiva is situated at the western corner of the lake. The belief that birds and wildlife in the area should not be harmed has traditionally protected fauna. Oligotrophic lake The TSI of

583-649: A molecular formula of C 55 H 70 O 6 N 4 Mg and a structure of (2- formyl )-chlorophyll a were deduced based on NMR, optical and mass spectra. Chlorophyll is vital for photosynthesis , which allows plants to absorb energy from light . Chlorophyll molecules are arranged in and around photosystems that are embedded in the thylakoid membranes of chloroplasts . In these complexes, chlorophyll serves three functions: The two currently accepted photosystem units are photosystem I and photosystem II , which have their own distinct reaction centres, named P700 and P680 , respectively. These centres are named after

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636-468: A nutrient-rich region with high net primary productivity may be naturally eutrophic. Nutrients carried into water bodies from non-point sources such as agricultural runoff, residential fertilisers, and sewage will all increase the algal biomass , and can easily cause an oligotrophic lake to become hypereutrophic. Although there is no absolute consensus as to which nutrients contribute the most to increasing primary productivity, phosphorus concentration

689-563: A rough estimate of biological condition of water bodies. Carlson's index was proposed by Robert Carlson in his 1977 seminal paper, "A trophic state index for lakes". It is one of the more commonly used trophic indices and is the trophic index used by the United States Environmental Protection Agency . The trophic state is defined as the total weight of biomass in a given water body at the time of measurement. Because they are of public concern,

742-593: A water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: The quantities of nitrogen , phosphorus , and other biologically useful nutrients are the primary determinants of a water body's TSI. Nutrients such as nitrogen and phosphorus tend to be limiting resources in standing water bodies, so increased concentrations tend to result in increased plant growth, followed by corollary increases in subsequent trophic levels . Consequently, trophic index may sometimes be used to make

795-470: A water body's trophic index should be. Chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants . Its name is derived from the Greek words χλωρός ( khloros , "pale green") and φύλλον ( phyllon , "leaf"). Chlorophyll allows plants to absorb energy from light. Chlorophylls absorb light most strongly in

848-528: Is 29 ha (72 acres) in size, followed by Tanjung Cho with an area of 16.95 ha (41.9 acres), and Ngojumba Cho with an area of 14.39 ha (35.6 acres). As sources of permanent fresh water they have high hydrological value. They feed on waters from various sources, such as seepage from the Ngozumpa glacier , a stream coming from the Renjo La pass from the north-west and another stream originating from

901-416: Is also applied to terrestrial habitats. Mesotrophic soils have moderate nutrient levels. A eutrophic water body, commonly a lake or pond, has high biological productivity. Due to excessive nutrients, especially nitrogen and phosphorus, these water bodies are able to support an abundance of aquatic plants. Usually, the water body will be dominated either by aquatic plants or algae. When aquatic plants dominate,

954-422: Is bound to proteins . Protochlorophyllide , one of the biosynthetic intermediates, occurs mostly in the free form and, under light conditions, acts as a photosensitizer , forming free radicals , which can be toxic to the plant. Hence, plants regulate the amount of this chlorophyll precursor. In angiosperms, this regulation is achieved at the step of aminolevulinic acid (ALA), one of the intermediate compounds in

1007-443: Is derived from glutamate and is synthesised along a branched biosynthetic pathway that is shared with heme and siroheme . Chlorophyll synthase is the enzyme that completes the biosynthesis of chlorophyll a : This conversion forms an ester of the carboxylic acid group in chlorophyllide a with the 20-carbon diterpene alcohol phytol . Chlorophyll b is made by the same enzyme acting on chlorophyllide b . The same

1060-404: Is known for chlorophyll d and f , both made from corresponding chlorophyllides ultimately made from chlorophyllide a . In Angiosperm plants, the later steps in the biosynthetic pathway are light-dependent. Such plants are pale ( etiolated ) if grown in darkness. Non-vascular plants and green algae have an additional light-independent enzyme and grow green even in darkness. Chlorophyll

1113-610: Is naturally vulnerable, as it lies in an ecologically fragile and unstable zone. The outburst of the Ngozumpa glacier is always a threat to the existence of the lakes. The Gokyo lake system of 19 lakes is spread over an area of 196.2 ha (485 acres) lying between 4,600 and 5,100 m (15,100 and 16,700 ft). The wetland lies at the head of the Dudh Kosi , which descends from Cho Oyu . The Gokyo Lakes are considered sacred by both Hindus and Buddhists . About 500 Hindus take

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1166-487: Is not soluble in water, and it is first mixed with a small quantity of vegetable oil to obtain the desired solution . In years 1950–1953 in particular, chlorophyll was used as a marketing tool to promote toothpaste, sanitary towels, soap and other products. This was based on claims that it was an odor blocker — a finding from research by F. Howard Westcott in the 1940s — and the commercial value of this attribute in advertising led to many companies creating brands containing

1219-443: Is sufficient for their needs. Anoxia is more common in the hypolimnion during the summer when mixing does not occur. In the absence of oxygen from the epilimnion, decomposition can cause hypoxia in the hypolimnion. Mesotrophic lakes are lakes with an intermediate level of productivity. These lakes are commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients. The term mesotrophic

1272-456: Is thought to be the main limiting factor in freshwater lakes. This is likely due to the prevalence of nitrogen-fixing microorganisms in these systems, which can compensate for a lack of readily available fixed nitrogen. In some coastal marine ecosystems, research has found nitrogen to be the key limiting nutrient, driving primary production independently of phosphorus. Nitrogen fixation cannot adequately supply these marine ecosystems, because

1325-590: Is usually classified as being in one of three possible classes: oligotrophic , mesotrophic or eutrophic . Lakes with extreme trophic indices may also be considered hyperoligotrophic or hypereutrophic (also "hypertrophic"). The table below demonstrates how the index values translate into trophic classes. Oligotrophic lakes generally host very little or no aquatic vegetation and are relatively clear, while eutrophic lakes tend to host large quantities of organisms, including algal blooms. Each trophic class supports different types of fish and other organisms, as well. If

1378-420: The blue portion of the electromagnetic spectrum as well as the red portion. Conversely, it is a poor absorber of green and near-green portions of the spectrum. Hence chlorophyll-containing tissues appear green because green light, diffusively reflected by structures like cell walls, is less absorbed. Two types of chlorophyll exist in the photosystems of green plants: chlorophyll a and b . Chlorophyll

1431-413: The stereochemistry of chlorophyll a was known, Robert Burns Woodward published a total synthesis of the molecule. In 1967, the last remaining stereochemical elucidation was completed by Ian Fleming , and in 1990 Woodward and co-authors published an updated synthesis. Chlorophyll f was announced to be present in cyanobacteria and other oxygenic microorganisms that form stromatolites in 2010;

1484-718: The Carlson index uses the algal biomass as an objective classifier of a lake or other water body's trophic status. According to the US EPA, the Carlson Index should only be used with lakes that have relatively few rooted plants and non-algal turbidity sources. Because they tend to correlate, three independent variables can be used to calculate the Carlson Index: chlorophyll pigments , total phosphorus and Secchi depth . Of these three, chlorophyll will probably yield

1537-450: The Mg center are often omitted for clarity. Appended to the chlorin ring are various side chains, usually including a long phytyl chain ( C 20 H 39 O ). The most widely distributed form in terrestrial plants is chlorophyll a . The only difference between chlorophyll a and chlorophyll b is that the former has a methyl group where the latter has a formyl group. This difference causes

1590-508: The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite. Land is dark gray, and places where MODIS could not collect data because of sea ice, polar darkness, or clouds are light gray. The highest chlorophyll concentrations, where tiny surface-dwelling ocean plants are, are in cold polar waters or in places where ocean currents bring cold water to the surface, such as around

1643-691: The Ngozumpa glacier in the east. These are glacier-fed freshwater wetlands and discharge water to the Dudh Kosi headway via Taujon Lake and Longabanga Lake. These lakes are deeper than previously assumed by the researchers. Fourth Lake (Thonak Cho) is the deepest lake (62.4 m) followed by Gokyo Lake which is 43 m. A direct connection between the Gokyo Lake and the upper Thonak Cho and the Ngozumpa Cho has not been observed, but these lakes may be connected via underground seepage water. The Gokyo Lake system

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1696-473: The Secchi depth. By translating the Secchi transparency values to a log base 2 scale, each successive doubling of biomass is represented as a whole integer index number. The Secchi depth, which measures water transparency, indicates the concentration of dissolved and particulate material in the water, which in turn can be used to derive the biomass. This relationship is expressed in the following equation: A lake

1749-493: The algal biomass in a lake or other water body reaches too high a concentration (say >80 TSI), massive fish die-offs may occur as decomposing biomass deoxygenates the water. Limnologists use the term " oligotrophic " or "hipotrophic" to describe lakes that have low primary productivity due to nutrient deficiency. (This contrasts against eutrophic lakes, which are highly productive due to an ample supply of nutrients, as can arise from human activities such as agriculture in

1802-416: The biosynthesis pathway. Plants that are fed by ALA accumulate high and toxic levels of protochlorophyllide; so do the mutants with a damaged regulatory system. The process of plant senescence involves the degradation of chlorophyll: for example the enzyme chlorophyllase ( EC 3.1.1.14 ) hydrolyses the phytyl sidechain to reverse the reaction in which chlorophylls are biosynthesised from chlorophyllide

1855-432: The depth to which the aforementioned seasonal mixing occurs, but they will be oxygen deficient below this depth. Therefore, oligotrophic lakes often support fish species such as lake trout , which require cold, well- oxygenated waters. The oxygen content of these lakes is a function of their seasonally mixed hypolimnetic volume. Hypolimnetic volumes that are anoxic will result in fish congregating in areas where oxygen

1908-412: The desired trophic index differs between stakeholders. Water-fowl enthusiasts (e.g. duck hunters) may want a lake to be eutrophic so that it will support a large population of waterfowl. Residents, though, may want the same lake to be oligotrophic, as this is more pleasant for swimming and boating. Natural resource agencies are generally responsible for reconciling these conflicting uses and determining what

1961-647: The environment . Eutrophic comes from the Greek eutrophos meaning "well-nourished", from eu meaning good and trephein meaning "to nourish". Hypertrophic or hypereutrophic lakes are very nutrient-rich lakes characterized by frequent and severe nuisance algal blooms and low transparency. Hypereutrophic lakes have a visibility depth of less than 3 feet (90 cm), they have greater than 40 micrograms/litre total chlorophyll and greater than 100 micrograms/litre phosphorus . The excessive algal blooms can also significantly reduce oxygen levels and prevent life from functioning at lower depths creating dead zones beneath

2014-417: The equator and along the shores of continents. It is not the cold water itself that stimulates the phytoplankton. Instead, the cool temperatures are often a sign that the water has welled up to the surface from deeper in the ocean, carrying nutrients that have built up over time. In polar waters, nutrients accumulate in surface waters during the dark winter months when plants cannot grow. When sunlight returns in

2067-521: The general structure: These compounds have also been identified in ripening fruits and they give characteristic autumn colours to deciduous plants. Chlorophyll maps from 2002 to 2024, provided by NASA , show milligrams of chlorophyll per cubic meter of seawater each month. Places where chlorophyll amounts are very low, indicating very low numbers of phytoplankton , are blue. Places where chlorophyll concentrations are high, meaning many phytoplankton were growing, are yellow. The observations come from

2120-440: The most accurate measures, as it is the most accurate predictor of biomass. Phosphorus may be a more accurate estimation of a water body's summer trophic status than chlorophyll if the measurements are made during the winter. Finally, the Secchi depth is probably the least accurate measure, but also the most affordable and expedient one. Consequently, citizen monitoring programs and other volunteer or large-scale surveys will often use

2173-438: The nitrogen fixing microbes are themselves limited by the availability of various abiotic factors like sunlight and dissolved oxygen. However, marine ecosystems are too broad a range of environments for one nutrient to limit all marine primary productivity. The limiting nutrient may vary in different marine environments according to a variety of factors like depth, distance from shore, or availability of organic matter. Often,

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2226-509: The oxidation of water into O 2 and H through several intermediates. This reaction is how photosynthetic organisms such as plants produce O 2 gas, and is the source for practically all the O 2 in Earth's atmosphere. Photosystem I typically works in series with Photosystem II; thus the P700 of Photosystem I is usually reduced as it accepts the electron, via many intermediates in

2279-472: The photon is transferred to an electron in a process called charge separation. The removal of the electron from the chlorophyll is an oxidation reaction. The chlorophyll donates the high energy electron to a series of molecular intermediates called an electron transport chain . The charged reaction center of chlorophyll (P680 ) is then reduced back to its ground state by accepting an electron stripped from water. The electron that reduces P680 ultimately comes from

2332-482: The presence of a fifth, ketone-containing ring beyond the four pyrrole-like rings. Most chlorophylls are classified as chlorins , which are reduced relatives of porphyrins (found in hemoglobin ). They share a common biosynthetic pathway with porphyrins, including the precursor uroporphyrinogen III . Unlike hemes, which contain iron bound to the N4 center, most chlorophylls bind magnesium . The axial ligands attached to

2385-410: The production of ATP (stored chemical energy) or to reduce NADP to NADPH . NADPH is a universal agent used to reduce CO 2 into sugars as well as other biosynthetic reactions. Reaction center chlorophyll–protein complexes are capable of directly absorbing light and performing charge separation events without the assistance of other chlorophyll pigments, but the probability of that happening under

2438-409: The spring and summer, the plants flourish in high concentrations. Synthetic chlorophyll is registered as a food additive colorant, and its E number is E140 . Chefs use chlorophyll to color a variety of foods and beverages green, such as pasta and spirits. Absinthe gains its green color naturally from the chlorophyll introduced through the large variety of herbs used in its production. Chlorophyll

2491-403: The surface. Likewise, large algal blooms can cause biodilution to occur, which is a decrease in the concentration of a pollutant with an increase in trophic level . This is opposed to biomagnification and is due to a decreased concentration from increased algal uptake. Both natural and anthropogenic factors can influence a lake or other water body's trophic index. A water body situated in

2544-421: The thylakoid membrane, by electrons coming, ultimately, from Photosystem II. Electron transfer reactions in the thylakoid membranes are complex, however, and the source of electrons used to reduce P700 can vary. The electron flow produced by the reaction center chlorophyll pigments is used to pump H ions across the thylakoid membrane, setting up a proton-motive force a chemiosmotic potential used mainly in

2597-409: The water tends to be clear. When algae dominate, the water tends to be darker. The algae engage in photosynthesis which supplies oxygen to the fish and biota which inhabit these waters. Occasionally, an excessive algal bloom will occur and can ultimately result in fish death, due to respiration by algae and bottom-living bacteria. The process of eutrophication can occur naturally and by human impact on

2650-499: The watershed.) Oligotrophic lakes are most common in cold, sparsely developed regions that are underlain by crystalline igneous , granitic bedrock. Due to their low algal production, these lakes consequently have very clear waters, with high drinking-water quality. Lakes that have intermixing of their layers are classified into the category of holomictic , whereas lakes that do not have interlayer mixing are permanently stratified and thus are termed meromictic . Generally, in

2703-404: The wavelength (in nanometers ) of their red-peak absorption maximum. The identity, function and spectral properties of the types of chlorophyll in each photosystem are distinct and determined by each other and the protein structure surrounding them. The function of the reaction center of chlorophyll is to absorb light energy and transfer it to other parts of the photosystem. The absorbed energy of

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2756-537: The wild. For example, Prochlorococcus , a cyanobacterium, uses 8-vinyl Chl a and b . Chlorophylls can be extracted from the protein into organic solvents. In this way, the concentration of chlorophyll within a leaf can be estimated. Methods also exist to separate chlorophyll a and chlorophyll b . In diethyl ether , chlorophyll a has approximate absorbance maxima of 430 nm and 662 nm, while chlorophyll b has approximate maxima of 453 nm and 642 nm. The absorption peaks of chlorophyll

2809-428: Was first isolated and named by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817. The presence of magnesium in chlorophyll was discovered in 1906, and was the first detection of that element in living tissue. After initial work done by German chemist Richard Willstätter spanning from 1905 to 1915, the general structure of chlorophyll a was elucidated by Hans Fischer in 1940. By 1960, when most of

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