17:
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processes. The first process is oxidation and methylation of inorganic and organic selenium by plant roots and microorganisms. The second process is biological mixing and associated oxidation of sediments from the burrowing of benthic invertebrates and feeding of fish and wildlife. The third
75:
Evidence for a selenium cycle is found through the study of selenium accumulator plants. These plants are found in semi-arid, seleniferous soils. The plants biosynthesize forms of organic selenium compounds and release the compounds into the soil when they decay. If the compounds were not
26:
Overview of selenium species, pathways and transformations in soil, water, atmosphere and their interfaces. Abiotic and biotic fluxes and transformations are indicated in italics at the corresponding arrows. Potential immobilization processes in soils are listed in the
745:
process is represented by physical movement and chemical oxidation from water circulation and mixing, such as current, wind, precipitation, and upwelling. The fourth process is from oxidation by plant photosynthesis.
701:
or sediments; or 3. it can remain in free solution. Over time, most of the selenium is taken in by organisms or bound to other solids. As the suspended material settles, the selenium accumulates in the top layer of
731:
by chemical or microbial activity in the water and sediment or by direct release from plants. Immobilization processes effectively remove selenium from the ecosystem, especially in slow-moving or still-water areas.
722:
or settling. After selenium is in the sediment, other chemical and microbial reduction may occur, causing insoluble organic, mineral, elemental, or adsorbed selenium. Some organic forms may be released into the
714:
Selenium can be removed from the ecosystem and bound in sediment through natural processes of chemical and microbial reduction of the selenate form to the selenite form. The reduction is followed by
680:
973:
920:
Lemly, A. Dennis (1999). "Selenium
Transport and Bioaccumulation in Aquatic Ecosystems: A Proposal for Water Quality Criteria Based on Hydrological Units".
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706:. Due to the dynamic flow in an aquatic ecosystem, selenium is usually only in the sediments temporarily before being cycled back into the system.
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form of the element and different organisms complete the cycle by oxidizing the reduced element to the initial state.
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152:
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oxidized, then an increase in organic selenium would be seen, but selenium in these areas is mainly inorganic.
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Winkel, Lenny; Vriens, Bas; Jones, Gerrad; Schneider, Leila; Pilon-Smits, Elizabeth; Bañuelos, Gary (2015).
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similar to the cycles of carbon, nitrogen, and sulfur. Within the cycle, there are organisms which
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In the selenium cycle it has been found that bacteria, fungi, and plants, especially species of
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881:. United States: National Fisheries Contaminant Research Center, Columbia, MO (USA).
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764:"Selenium Cycling Across Soil-Plant-Atmosphere Interfaces: A Critical Review"
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may be able to oxidize selenium of valence zero to selenium of valence +6.
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65:
57:
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36:
951:
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Selenium is made available to the food chain through four oxidation and
697:: 1. it can be absorbed or ingested by organisms; 2. it can bind with
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Material was copied from this source, which is available under a
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Aquatic cycling of selenium: implications for fish and wildlife
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Creative
Commons Attribution 4.0 International License
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823:Shrift, A. (1964). "A Selenium Cycle in Nature?".
693:There are three fates of dissolved selenium in an
56:, metabolize the most oxidized forms of selenium,
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718:to clay, reaction with iron species, and
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922:Ecotoxicology and Environmental Safety
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22:Selenium pathways and transformations
7:
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589:Biogeochemical planetary boundaries
1245:Human impact on the nitrogen cycle
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877:Lemly, A.D.; Smith, G.L. (1988).
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1292:
804:
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647:
99:
1:
1250:Lichens and nitrogen cycling
1105:Marine biogeochemical cycles
334:Marine biogeochemical cycles
68:. It is also thought that
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1288:
35:is a biological cycle of
1238:Arctic methane emissions
1233:clathrate gun hypothesis
1004:carbonate–silicate cycle
710:Immobilization processes
402:Arctic methane emissions
397:clathrate gun hypothesis
312:Carbonate–silicate cycle
1270:Phosphorus assimilation
1172:environmental chemistry
556:environmental chemistry
934:10.1006/eesa.1998.1737
736:Mobilization processes
28:
1265:Nitrogen assimilation
983:Biogeochemical cycles
93:Biogeochemical cycles
19:
1319:Biogeochemical cycle
1280:Planetary boundaries
1184:carbon sequestration
1014:oceanic carbon cycle
239:nitrogen and lichens
1275:Sulfur assimilation
1216:Ocean acidification
837:1964Natur.201.1304S
831:(4926): 1304–1305.
577:Ocean acidification
387:Atmospheric methane
87:Part of a series on
80:Aquatic ecosystems
29:
1306:
1305:
1260:Nitrogen fixation
1228:Methane clathrate
1209:mycorrhizal fungi
1162:geochemical cycle
1009:deep carbon cycle
845:10.1038/2011304a0
781:10.3390/nu7064199
695:aquatic ecosystem
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690:
546:geochemical cycle
392:Methane clathrate
190:mycorrhizal fungi
180:deep carbon cycle
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1179:Biosequestration
1167:chemical cycling
1098:deep water cycle
1068:Phosphorus cycle
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774:(6): 4199–4239.
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563:Biosequestration
551:chemical cycling
261:Phosphorus cycle
124:deep water cycle
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1051:Nutrient cycle
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1046:Nitrogen cycle
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1021:Chlorine cycle
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928:(2): 150–156.
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379:Methane cycle
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170:Sequestration
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34:
23:
18:
1088:Sulfur cycle
1083:Silica cycle
1077:
1056:Oxygen cycle
999:Carbon cycle
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921:
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878:
828:
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771:
767:
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739:
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510:
506:ozone–oxygen
418:Other cycles
326:Marine cycle
307:Silica cycle
278:assimilation
273:Sulfur cycle
266:assimilation
256:Oxygen cycle
249:assimilation
229:human impact
140:Carbon cycle
74:
51:
49:
32:
30:
27:frame-inset.
21:
1204:viral shunt
1194:soil carbon
1189:carbon sink
1093:Water cycle
903:|work=
742:methylation
353:viral shunt
185:soil carbon
175:carbon sink
158:terrestrial
153:atmospheric
119:Water cycle
111:Water cycle
1313:Categories
1073:Rock cycle
1031:Iron cycle
749:References
725:atmosphere
716:adsorption
294:Rock cycle
53:Astragalus
1221:acid rain
1126:GEOTRACES
905:ignored (
895:cite book
768:Nutrients
614:GEOTRACES
582:acid rain
496:manganese
43:the most
1324:Selenium
1298:Category
942:10051364
853:14151413
800:26035246
704:sediment
654:Category
516:vanadium
511:selenium
466:fluorine
456:chromium
451:chlorine
426:aluminum
244:fixation
66:selenide
62:selenite
58:selenate
45:oxidized
37:selenium
887:7253805
861:4169144
833:Bibcode
791:4488781
501:mercury
491:lithium
446:cadmium
441:bromine
431:arsenic
163:oceanic
24:
991:Cycles
940:
885:
859:
851:
825:Nature
798:
788:
652:
476:iodine
461:copper
148:Global
41:reduce
1141:SOLAS
1131:IMBER
1061:ozone
857:S2CID
727:from
633:SOLAS
623:IMBER
436:boron
64:, to
1136:NOBM
1121:DAAC
938:PMID
907:help
883:OSTI
849:PMID
796:PMID
628:NOBM
609:DAAC
521:zinc
486:lead
481:iron
471:gold
31:The
930:doi
841:doi
829:201
786:PMC
776:doi
60:or
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893:{{
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
