In situ#Earth and atmospheric sciences

The term in situ is not found in Classical Latin. Its earliest recorded use is in Late Latin during the 4th century, with the first known instance by Augustine of Hippo. The term was widely used in Medieval Latin.{{rp|page=1536}} The term's earliest known use in the English language dates back to the mid-17th century. The Oxford English Dictionary cites the first English-language appearance of in situ in 1648 in the writings of William Molins, author of the anatomical text Myskotomia. The usage of in situ in scientific literature increased from the late 19th century onward, initially in medicine and engineering, including geological surveys and petroleum extraction. During this period, the term described analyses conducted within the living human body or inside oil wells, among other applications.{{rp|page=1534}} In situ entered French medical discourse by 1877 in the {{lang|fr|Journal de médecine et de chirurgie pratiques}} ({{translation|Journal of Practical Medicine and Surgery}}).{{Cite web|url=https://stella.atilf.fr/Dendien/scripts/tlfiv5/advanced.exe?8;s=2172540075; |title=in situ |website=Trésor de la langue française informatisé |publisher=ATILF – Analyse et traitement informatique de la langue française |access-date=18 April 2025 |lang=fr }} The compound term carcinoma in situ, referring to abnormal cells that confined to their original location without invasion of surrounding tissue, was first used in a 1932 paper by U.S. surgical pathologist Albert C. Broders.{{Cite OED|carcinoma in situ|1023159588}}{{cite journal |last=Wright |first=James R. Jr. |title=Albert C. Broders' paradigm shifts involving the prognostication and definition of cancer |journal=Archives of Pathology & Laboratory Medicine |date=2012 |volume=136 |issue=11 |pages=1437–1446 |doi=10.5858/arpa.2011-0567-HP |pmid=23106590 }}

The concept of in situ in contemporary art emerged as a framework in the late 1960s and 1970s, referring to artworks created specifically for a particular space.{{rp|pages=160–162}} By the mid-1980s, the term was adopted in materials science, particularly in the field of heterogeneous catalysis, where a catalyst in one phase facilitates a chemical reaction in a different phase. Its usage later expanded beyond catalysis and is now applied across various disciplines within materials science.{{cite journal |last1=Peterson |first1=Vanessa K. |author-link=Vanessa Peterson |last2=Bianchini |first2=Matteo |last3=Chapman |first3=Karena W. |author-link3=Karena Chapman |last4=Elice |first4=Martina |last5=Hibbert |first5=David Brynn |title=Terms of Latin origin relating to sample characterization (IUPAC Technical Report) |journal=Pure and Applied Chemistry |date=2024 |volume=96 |issue=11 |pages=1531–1540 |doi=10.1515/pac-2022-1103 |doi-access=free |publisher=De Gruyter}}{{rp|page=1534}} {{As of|August 2022}}, the term in{{nbsp}}situ had been used in more than 910,000 scientific publications since 1874, while ex{{nbsp}}situ had appeared in over 29,000 scientific publications since 1958.{{rp|page=1535}} In{{nbsp}}situ remains one of the most widely used and versatile Latin terms in contemporary medical discourse.

In astronomy, in situ measurement involves collecting data directly at or near a celestial object using spacecraft or instruments physically present at the location.{{cite book |last=Casoli |first=Fabienne |author-link=Fabienne Casoli |editor-last=Lasota |editor-first=Jean-Pierre |chapter=10. The Future of Space Astronomy |title=Astronomy at the Frontiers of Science |publisher=Springer Netherlands |year=2011 |pages=175–176 |isbn=978-94-007-1658-2 |url=https://books.google.com/books?id=XGwTsKteQAkC |via=Google Books |access-date=23 February 2025}} For example, the Parker Solar Probe conducts in situ studies of Sun's atmosphere,{{cite journal |last=Phan |first=T. D. |author2=Bale, S. D. |author3=Eastwood, J. P. |author4=Larson, D. E. |author5=MacDowall, R. J. |author6=Pulupa, M. |author7=Whittlesey, P. |author8=Mozer, F. S. |author9=Drake, J. F. |author10=Oieroset, M. |author11=Shay, M. A. |author12=Haggerty, C. C. |author13=Halekas, J. S. |author14=McManus, M. D. |author15=Verniero, J. L. |author16=Case, A. W. |author17=Kasper, J. C. |author18=Korreck, K. E. |author19=Stevens, M. L. |author20=Szabo, A. |author21=MacDowall, R. J. |author22=Malaspina, D. M. |author23=Bonnell, J. W. |author24=Dudok de Wit, T. |author25=Goetz, K. |author26=Harvey, P. R. |author27=Horbury, T. S. |author28=Livi, R. |author29=Paulson, K. |author30=Raouafi, N. E. |author31=Velli, M. |title=Parker Solar Probe In Situ Observations of Magnetic Reconnection Exhausts during Encounter 1 |journal=The Astrophysical Journal Supplement Series |volume=246 |issue=2 |pages=34 |date=February 2020 |doi=10.3847/1538-4365/ab55ee |doi-access=free |arxiv=2001.06048 |bibcode=2020ApJS..246...34P}} while the Cassini–Huygens mission similarly analyzed Saturn's magnetosphere.{{cite web |title=Cassini Orbiter |url=https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/ |quote=The fields and particles instruments took "in situ" (on site) direct sensing measurements [...] |website=NASA Science |date=21 August 2018 |publisher=NASA |access-date=23 February 2025 |archive-date=16 February 2025 |archive-url=https://web.archive.org/web/20250216153855/https://science.nasa.gov/mission/cassini/spacecraft/cassini-orbiter/ |url-status=live }} In situ formation refers to astronomical objects that formed at their current locations without significant migration. Some theories propose that planets, such as Earth, formed in their present orbits rather than moving from elsewhere. Star clusters may form within their host galaxy, rather than being accreted from external sources.{{cite journal |last1=Chiang |first1=Eugene |last2=Laughlin |first2=Gregory P. |author-link2=Gregory P. Laughlin |title=The minimum-mass extrasolar nebula: in situ formation of close-in super-Earths |journal=Monthly Notices of the Royal Astronomical Society |date=June 2013 |volume=431 |issue=4 |pages=3444–3455 |doi=10.1093/mnras/stt424 |doi-access=free |bibcode=2013MNRAS.431.3444C |arxiv=1211.1673 }}{{cite journal |last1=D'Angelo |first1=Gennaro |last2=Bodenheimer |first2=Peter |title=In Situ and Ex Situ Formation Models of Kepler 11 Planets |journal=The Astrophysical Journal |date=September 2016 |volume=828 |issue=1 |pages=33 |doi=10.3847/0004-637X/828/1/33 |doi-access=free |arxiv=1606.08088 |bibcode=2016ApJ...828...33D }}

{{Further|In situ hybridization}}

File:HCR-FISH visualization of collagen expression in P. waltl.jpg of collagen in Iberian ribbed newt, via Hybridization Chain Reaction RNA Fluorescence In Situ Hybridization]]

In cell biology, in situ techniques allow the examination of cells or tissues within their native environment, preserving their natural structure and context. These approaches contrast with techniques requiring the extraction or isolation of cellular components. One example is in situ hybridization (ISH), a technique designed to identify and localize specific nucleic acid sequences within intact cells or tissue sections. {{Abbr|ISH|In situ hybridization}} employs labeled probes, which are strands of nucleic acids engineered to bind selectively to target sequences. These probes are tagged with detectable markers, such as fluorophores or radioactive isotopes, enabling visualization of the precise spatial distribution of the targeted DNA or RNA. By maintaining the structural integrity of the sample, the technique facilitates mapping of genetic material within its original cellular or tissue framework.{{cite journal |last=Jensen |first=Ellen |title=Technical Review: In Situ Hybridization |journal=The Anatomical Record |volume=297 |issue=8 |pages=1349–1353 |date=August 2014 |doi=10.1002/ar.22944|pmid=24810158 }}{{cite book |last1=Lehmann|first1=Ruth|title=Chapter 30 in Situ Hybridization to RNA |date=1994 |url=https://www.sciencedirect.com/science/article/pii/S0091679X08609334|volume=44|pages=575–598|editor-last=Goldstein|editor-first=Lawrence S. B.|publisher=Academic Press |doi=10.1016/s0091-679x(08)60933-4 |access-date=26 February 2025 |last2=Tautz|first2=Diethard|series=Methods in Cell Biology|pmid=7535885|isbn=9780125641456|editor2-last=Fyrberg|editor2-first=Eric A.}}

In biological field research, the term in situ refers to the study of living organisms within their natural habitat. This includes collecting biological samples, conducting experiments, measuring abiotic factors, and documenting ecological or behavioral observations without relocating the subject.{{cite journal |last1=Ramírez-Castañeda |first1=Valeria |last2=Westeen |first2=Erin P. |last3=Frederick |first3=Jeffrey |last4=Amini |first4=Sina |last5=Wait |first5=Daniel R. |last6=Achmadi |first6=Anang S. |last7=Andayani |first7=Noviar |last8=Arida |first8=Evy |title=A set of principles and practical suggestions for equitable fieldwork in biology |journal=Proceedings of the National Academy of Sciences of the United States of America |year=2022 |volume=119 |issue=34 |pages=e2122667119 |doi=10.1073/pnas.2122667119|doi-access=free |pmid=35972961 |pmc=9407469 |bibcode=2022PNAS..11922667R }}{{cite journal |last1=Brown |first1=Culum |last2=Jones |first2=Felicity |last3=Braithwaite |first3=Victoria A. |title=In situ examination of boldness–shyness traits in the tropical poeciliid, Brachyraphis episcopi |journal=Animal Behaviour |volume=70 |issue=5 |pages=1003–1009 |date=November 2005 |doi=10.1016/j.anbehav.2004.12.022}}

In organic chemistry, in situ refers to processes that take place within the reaction mixture without isolating intermediates. This approach is useful for handling unstable compounds that decompose rapidly, and enhances laboratory safety by eliminating the need to isolate potentially hazardous intermediates. In one-pot synthetic sequences, in{{nbsp}}situ work-up modifications enable multiple reaction steps to proceed within a single vessel, reducing exposure to unstable or hazardous substances, such as azide intermediates,{{efn|Sodium azide and its conjugate acid—hydrazoic acid—are both referred to as azide.{{rp|page=683}} Azides are explosophores{{cite journal |last1=Treitler |first1=Daniel S. |last2=Leung |first2=Simon |title=How Dangerous is too Dangerous? A Perspective on Azide Chemistry |journal=The Journal of Organic Chemistry |date=2 September 2022 |volume=87 |issue=17 |pages=11293–11295 |doi=10.1021/acs.joc.2c01402 |pmid=36052475 |s2cid=252009657 |url=https://pubs.acs.org/doi/10.1021/acs.joc.2c01402 |access-date=27 February 2025 |issn=0022-3263 |archive-date=17 November 2023 |archive-url=https://web.archive.org/web/20231117135658/https://pubs.acs.org/doi/10.1021/acs.joc.2c01402 |url-status=live |url-access=subscription }} and respiratory poisons.{{cite journal | last1=Tat | first1=John | last2=Heskett | first2=Karen | last3=Satomi | first3=Shiho | last4=Pilz | first4=Renate B. | last5=Golomb | first5=Beatrice A. | last6=Boss | first6=Gerry R. | title=Sodium azide poisoning: A narrative review |journal=Clinical Toxicology | date=2021 | volume=59 | issue=8 | issn=1556-3650 | pmid=34128439 | pmc=8349855 | doi=10.1080/15563650.2021.1906888 | pages=683–697}}{{rp|page=684}}}} which may pose safety risks if isolated.{{cite journal|last= Hayashi | first = Yujiro |date = 2016 |title = Pot economy and one-pot synthesis |journal= Chemical Science | volume = 7 | issue = 2 | pages = 866–880 |doi = 10.1039/C5SC02913A | pmid = 28791118 | pmc = 5529999 }}{{rp|page=872}} Another example is the Corey–Chaykovsky reagent, a sulfur ylide, is generated in{{nbsp}}situ by deprotonating sulfonium halides with a strong base.{{cite web |title=Corey–Chaykovsky reaction |url=https://www.organic-chemistry.org/namedreactions/corey-chaykovsky-reaction.shtm |website=Organic Chemistry Portal |access-date=24 February 2025 |archive-url=https://web.archive.org/web/20241013015827/https://www.organic-chemistry.org/namedreactions/corey-chaykovsky-reaction.shtm |archive-date=13 October 2024 }}{{cite journal|last1= Xiang | first1 = Y. | last2 = Fan | first2 = X. | last3 = Cai | first3 = P.-J. | last4 = Yu | first4 = Z.-X. | date = 2019 |title = Understanding regioselectivities of Corey–Chaykovsky reactions of dimethylsulfoxonium methylide (DMSOM) and dimethylsulfonium methylide (DMSM) toward enones: A DFT study |journal= European Journal of Organic Chemistry | volume = 2019 | issue = 3 | pages = 582–590 |doi = 10.1002/ejoc.201801216 }} This approach is used because unstablized sulfur ylides are highly reactive. If isolated, the ylide could decompose or lose reactivity, making its direct generation and use in the reaction mixture more practical.{{cite journal| last1 = Bisag | first1 = Giorgiana Denisa | last2 = Ruggieri | first2 = Silvia | last3 = Fochi | first3 = Mariafrancesca | last4 = Bernardi | first4 = Luca |title = Sulfoxonium ylides: simple compounds with chameleonic reactivity | journal = Organic & Biomolecular Chemistry | volume = 18 | issue = 43 | pages = 8793–8809 | year = 2020 |doi = 10.1039/D0OB01822H | pmid = 33084717 | hdl = 11585/787170 | url = https://pubs.rsc.org/en/content/articlelanding/2020/ob/d0ob01822h | hdl-access = free }}

Analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, Raman spectroscopy, and mass spectrometry facilitate real-time monitoring of in{{nbsp}}situ reactions. These methods enable researchers to detect short-lived substances that form during a reaction, such as intermediates that might not be stable enough to isolate, and adjust conditions to improve the process—all without disturbing the reaction itself.{{cite journal |title=In situ Spectroscopy: Delineating the mechanistic understanding of electrochemical energy reactions |author1-first=Jayaraman |author1-last=Theerthagiri |author2-first=K. |author2-last=Karuppasamy |author3-first=C.|author3-last=Justin Raj|author4-first=M.L.|author4-last=Aruna Kumari|author5-first=L.|author5-last=John Kennedy|author6-first=Gilberto|author6-last=Maia|author7-first=Neshanth|author7-last=Vadivel|author8-first=Arun Prasad|author8-last=Murthy|author9-first=Akram|author9-last=Alfantazi|author10-first=Soorathep|author10-last=Kheawhom |author11-first=Myong Yong |author11-last=Choi |journal=Progress in Materials Science |volume=152 |year=2025 |doi=10.1016/j.pmatsci.2025.101451 |issn=0079-6425}}{{cite journal| last1 = Zhang | first1 = Dongao | last2 = Liu | first2 = Xuan | last3 = Zhao | first3 = Yu | last4 = Zhang | first4 = Hua | last5 = Rudnev | first5 = Alexander V. | last6 = Li | first6 = Jian-Feng |title = In situ Raman spectroscopic studies of CO₂ reduction reactions: from catalyst surface structures to reaction mechanisms |journal = Chemical Science | year = 2025 | volume = 16 | issue = 12 | pages = 4916–4936 | doi = 10.1039/D5SC00569H | pmid = 40007664 | pmc = 11848642 }}{{cite journal | last1 = Buser | first1 = Jonas Y. | last2 = McFarland | first2 = Adam D. | title = Reaction characterization by flow NMR: quantitation and monitoring of dissolved H₂ via flow NMR at high pressure | journal = Chemical Communications | volume = 50 | issue = 32 | pages = 4234–4237 | year = 2014 | doi = 10.1039/C4CC00055B | pmid = 24633225 | url = https://pubs.rsc.org/en/content/articlelanding/2014/cc/c4cc00055b | archive-date = 14 October 2024 | access-date = 27 February 2025 | archive-url = https://web.archive.org/web/20241014032133/https://pubs.rsc.org/en/Content/ArticleLanding/2014/CC/C4CC00055B | url-status = live | url-access = subscription }}

In electrochemistry, in situ experiments are performed under the normal operating conditions of an electrochemical cell, with the electrode maintained at a controlled potential (typically by a potentiostat).{{cite book|last1=Kolb |first1=Dieter M. | last2=Simeone | first2=Felice C. | chapter=Characterization and Modification of Electrode Surfaces by In Situ STM | title=Scanning Tunneling Microscopy in Surface Science, Nanoscience and Catalysis | editor1-last=Bowker | editor1-first=Michael | editor2-last=Davies | editor2-first=Philip R. |url=https://books.google.com/books?id=5K16aBTAmMYC |via=Google Books | publisher=Wiley-VCH | year=2009 | pages=119–122 | isbn=9783527319824 }} By contrast, ex situ experiments occur outside those operating conditions, usually without potential control—for example, after the electrode has been removed from the cell or left at open-circuit. Maintaining potential control in in situ measurements preserves the electrochemical environment at the electrode–electrolyte interface, ensuring that the double layer and ongoing electron-transfer reactions remain intact at a given electrode potential.{{cite journal|last1=Brummel | first1=Olaf | last2=Lykhach | first2=Yaroslava | last3=Ralaiarisoa | first3=Maryline |title=A Versatile Approach to Electrochemical In Situ Ambient-Pressure X-ray Photoelectron Spectroscopy: Application to a Complex Model Catalyst | journal=The Journal of Physical Chemistry Letters | year=2022 | volume=13 | issue=47 | pages=11015–11022| doi=10.1021/acs.jpclett.2c03004 | pmid=36411106 | hdl=11311/1229225 | hdl-access=free }}{{cite journal| last1=Brimaud | first1=Sylvain | last2=Jusys | first2=Zenonas | last3=Behm | first3=R. Jürgen | title=Shape-selected nanocrystals for in situ spectro-electrochemistry studies on structurally well defined surfaces under controlled electrolyte transport: A combined in situ ATR-FTIR/online DEMS investigation of CO electrooxidation on Pt | journal=Beilstein Journal of Nanotechnology | year=2014 | volume=5 | pages=735–746 | doi=10.3762/bjnano.5.86 | pmid=24991511 | pmc=4077536 }}

{{Broader|Structural health monitoring}}

{{Further|In situ resource utilization}}

In aerospace structural health monitoring, in situ inspection involves diagnostic techniques that assess components within their operational environments, avoiding the need for disassembly or service interruptions. The nondestructive testing (NDT) methods commonly used for in situ damage detection include infrared thermography, which measures thermal emissions to identify structural anomalies but is less effective on low-emissivity materials;{{cite web | url=https://www.flir.com/discover/professional-tools/how-does-emissivity-affect-thermal-imaging/?srsltid=AfmBOopyv0S_iwA3Cz9ssDWC8GJny8SnmJWj-ytZ4VzunW6git0eJ1aD |archive-url=https://web.archive.org/web/20250218180532/https://www.flir.com/discover/professional-tools/how-does-emissivity-affect-thermal-imaging/?srsltid=AfmBOopyv0S_iwA3Cz9ssDWC8GJny8SnmJWj-ytZ4VzunW6git0eJ1aD |archive-date=18 February 2025 | title=How Does Emissivity Affect Thermal Imaging? | date=1 November 2021 |access-date=2024-10-12 |publisher=Teledyne FLIR }} speckle shearing interferometry (shearography), which analyzes surface deformation patterns but requires carefully controlled environmental conditions;{{cite book | chapter-url=https://doi.org/10.1007/978-3-319-26553-7_3 | doi=10.1007/978-3-319-26553-7_3 | chapter=Shearography | title=Handbook of Advanced Nondestructive Evaluation | date=2019 | last1=Yang | first1=Lianxiang | last2=Li | first2=Junrui | pages=383–384 | isbn=978-3-319-26552-0 }} and ultrasonic testing, which uses sound waves to detect internal defects in composite materials but can be time-intensive for large structures.{{cite book | chapter-url=https://doi.org/10.1016/B978-0-08-102706-6.00018-0 | doi=10.1016/B978-0-08-102706-6.00018-0 | chapter=Sensing solutions for assessing and monitoring underwater systems | title=Sensor Technologies for Civil Infrastructures | date=2022 | last1=Rizzo | first1=P. | pages=362–363 | isbn=978-0-08-102706-6 }} Despite these individual limitations, the integration of these complementary techniques enhances overall diagnostic accuracy. Another approach involves real-time monitoring using alternating current (AC) and direct current (DC) sensor arrays. These systems detect structural degradation, including matrix discontinuities, interlaminar delaminations, and fiber fractures, by analyzing variations in electrical resistance and capacitance within composite laminate structures.{{cite journal |last1=Addepalli |first1=Sri |last2=Roy |first2=Rajkumar |last3=Axinte |first3=Dragoş |last4=Mehnen |first4=Jörn |title='In-situ' Inspection Technologies: Trends in Degradation Assessment and Associated Technologies |journal=Procedia CIRP |date=2017 |volume=59 |page=37 |doi=10.1016/j.procir.2016.10.003 }}

File:Orion Artemis I Selfie 1.jpg]]

Future space exploration and terraforming efforts may depend on in situ resource utilization, reducing reliance on Earth-based supplies. Proposed missions, such as Orion and Mars Direct, have explored this approach by leveraging locally available materials. The Orion space vehicle was once considered for propulsion using fuel extracted from the Moon, while Mars Direct relies on the Sabatier reaction to synthesize methane and water from atmospheric carbon dioxide and hydrogen on Mars.{{cite journal | last1 = Zubrin | first1 = Robert M. |author-link1=Robert Zubrin | last2 = Muscatello | first2 = Anthony C. | last3 = Berggren | first3 = Michael | title = Integrated Mars In Situ Propellant Production System | journal =Journal of Aerospace Engineering | volume = 26 | issue = 1 | pages = 44–56 | year = 2013 | doi = 10.1061/(ASCE)AS.1943-5525.0000201 }}{{cite web | last = Sercel | first = Joel | author-link = Joel C. Sercel | title = Lunar Polar Propellant Mining Outpost (LPMO): A Breakthrough for Lunar Exploration & Industry | website = NASA | date = 7 April 2020 | url = https://www.nasa.gov/general/lunar-polar-propellant-mining-outpost-lpmo-a-breakthrough-for-lunar-exploration-industry/ | access-date = 2 March 2025 | archive-date = 30 January 2025 | archive-url = https://web.archive.org/web/20250130122447/https://www.nasa.gov/general/lunar-polar-propellant-mining-outpost-lpmo-a-breakthrough-for-lunar-exploration-industry/ | url-status = live }}

{{Further|In situ polymerization}}

In biological engineering, in situ describes experimental treatments applied to cells or tissues while they remain intact, rather than using extracts. It also refers to assays or manipulations performed on whole tissues without disrupting their natural structure.{{cite book |last=Goyal |first=M. R. |author-link=Megh R. Goyal |year=2018 |title=Scientific and Technical Terms in Bioengineering and Biological Engineering |publisher=Apple Academic Press, Taylor & Francis |isbn=9781351360357 }}{{rp|pages=295–296}}

In biomedical engineering, in situ polymerization is used to produce protein nanogels, which serve as a versatile platform for the storage and release of therapeutic proteins. This approach has applications in cancer treatment, vaccination, diagnostics, regenerative medicine, and therapies for loss-of-function genetic diseases.{{cite journal|last1=Ye|first1=Yanqi|last2=Yu|first2=Jicheng|last3=Gu|first3=Zhen|year=2015|title=Versatile Protein Nanogels Prepared by In Situ Polymerization|journal=Macromolecular Chemistry and Physics|volume=217|issue=3|pages=333–343|doi=10.1002/macp.201500296}}

{{Further|Cast-in-place concrete}}

In construction engineering, in situ construction refers to building work carried out directly on-site using raw materials, as opposed to prefabrication, where components are manufactured off-site and assembled on-site. In situ concrete is poured at its final location, offering structural stability compared to precast construction.{{rp|pages=117–119}} In wall construction, reinforcing bars are assembled first, followed by the installation of formwork to contain the poured concrete. Once the concrete has cured, the formwork is removed, leaving the wall in place.{{cite book |last=Collum |first=Bill |title=Nuclear Facilities: A Designer's Guide |chapter=Chapter 5. Structural |year=2016 |publisher=Elsevier Science |location=Netherlands |series=Woodhead Publishing Series in Energy |volume=112 |isbn=9780081019399}}{{rp|page=117}} Prefabrication, by contrast, enhances efficiency by reducing on-site labor and accelerating project timelines, though it requires precise pre-planning and incurs higher manufacturing and transportation costs.{{cite journal |last1=Tavares |first1=V. |last2=Soares |first2=N. |last3=Raposo |first3=N. |last4=Marques |first4=P. |last5=Freire |first5=F. |title=Prefabricated versus conventional construction: Comparing life-cycle impacts of alternative structural materials |journal=Journal of Building Engineering |volume=41 |year=2021 |pages=102705 |issn=2352-7102 |doi=10.1016/j.jobe.2021.102705}}{{cite journal |last1=Zhang |first1=Wei |last2=Lee |first2=Ming Wai |last3=Jaillon |first3=Lara |last4=Poon |first4=Chi-Sun |title=The hindrance to using prefabrication in Hong Kong's building industry |journal=Journal of Cleaner Production |volume=204 |year=2018 |pages=70–81 |issn=0959-6526 |doi=10.1016/j.jclepro.2018.08.190 |bibcode=2018JCPro.204...70Z }}{{cite journal |last1=Chen |first1=Ying |last2=Okudan |first2=Gül E. |last3=Riley |first3=David R. |title=Decision support for construction method selection in concrete buildings: Prefabrication adoption and optimization |journal=Automation in Construction |volume=19 |issue=6 |year=2010 |pages=665–675 |issn=0926-5805 |doi=10.1016/j.autcon.2010.02.011}}

In geotechnical engineering, the term in situ describes soil in its natural, undisturbed state,{{cite web | author = New Zealand Geotechnical Society Inc. | editor1-last = Burns | editor1-first = David | editor2-last = Farqhuar | editor2-first = Geoffrey | editor3-last = Mills | editor3-first = Mandy | editor4-last = Williams | editor4-first = Ann | date = December 2005 | title = Field Description of Soil and Rock: Guideline for the Field Classification and Description of Soil and Rock for Engineering Purposes | url = https://www.geoengineer.org/storage/education/64/general_file_collection/17735/NZGS-2005-Field-description-of-soil-and-rock.pdf | access-date = 27 February 2025 | website = geoengineer.org | archive-date = 18 May 2024 | archive-url = https://web.archive.org/web/20240518155651/https://www.geoengineer.org/storage/education/64/general_file_collection/17735/NZGS-2005-Field-description-of-soil-and-rock.pdf | url-status = live }}{{rp|page=15}} as opposed to fill material, which has been excavated and relocated. The differences between undisturbed soil and fill material affect how well a site can support structures, install underground utilities, and manage water drainage. Proper assessment of soil conditions is necessary to prevent issues such as uneven settling, unstable foundations, and poor water infiltration.{{cite encyclopedia |last1=Nimmo |first1=John R. |last2=Shillito |first2=Rose M. |title=Infiltration of Water Into Soil |encyclopedia=Oxford Research Encyclopedia of Environmental Science |date=2023 |publisher=Oxford University Press |doi=10.1093/acrefore/9780199389414.013.768 |isbn=978-0-19-938941-4 }}{{cite journal |last1=Cardarelli |first1=Ettore |last2=Cercato |first2=Michele |last3=Di Filippo |first3=Gerardina |title=Assessing foundation stability and soil-structure interaction through integrated geophysical techniques: a case history in Rome (Italy) |journal=Near Surface Geophysics |volume=5 |issue=2 |pages=141–147 |date=December 2007 |doi=10.3997/1873-0604.2006026 |bibcode=2007NSGeo...5..141C }}

{{Further|In-situ processing|In-place algorithm}}

In computer science, in situ refers to the use of technology and user interfaces to provide continuous access to situationally relevant information across different locations and contexts.{{cite journal |last1=Ens |first1=Barrett |last2=Irani |first2=Pourang |title=Spatial Analytic Interfaces: Spatial User Interfaces for In Situ Visual Analytics |journal=IEEE Computer Graphics and Applications |date=March 2017 |volume=37 |issue=2 |pages=66–79 |doi=10.1109/MCG.2016.38 |pmid=28113834 }}{{cite journal |last1=Willett |first1=Wesley |last2=Jansen |first2=Yvonne |last3=Dragicevic |first3=Pierre |title=Embedded Data Representations |journal=IEEE Transactions on Visualization and Computer Graphics |date=January 2017 |volume=23 |issue=1 |pages=461–470 |doi=10.1109/TVCG.2016.2598608 |pmid=27875162 |url=https://hal.inria.fr/hal-01377901/file/embedded-data-representations.pdf |archive-date=24 September 2019 |access-date=24 September 2019 |archive-url=https://web.archive.org/web/20190924161116/https://hal.inria.fr/hal-01377901/file/embedded-data-representations.pdf |url-status=live }} Examples include athletes viewing biometric data on smartwatches to improve their performance{{cite book |doi=10.1145/3154862.3154879 |chapter=Data representations for in-situ exploration of health and fitness data |title=Proceedings of the 11th EAI International Conference on Pervasive Computing Technologies for Healthcare |date=2017 |last1=Amini |first1=Fereshteh |last2=Hasan |first2=Khalad |last3=Bunt |first3=Andrea |last4=Irani |first4=Pourang |pages=163–172 |isbn=978-1-4503-6363-1 }} or a presenter looking at tips on a smart glass to reduce their speaking rate during a speech.{{cite book |doi=10.1145/2678025.2701386 |chapter=Rhema: A Real-Time In-Situ Intelligent Interface to Help People with Public Speaking |title=Proceedings of the 20th International Conference on Intelligent User Interfaces |date=2015 |last1=Tanveer |first1=M. Iftekhar |last2=Lin |first2=Emy |last3=Hoque |first3=Mohammed (Ehsan) |pages=286–295 |isbn=978-1-4503-3306-1 }}

An algorithm is said to be an in situ algorithm, or in-place algorithm, if the extra amount of memory required to execute the algorithm is O(1),{{cite journal |last1=Munro |first1=J. Ian |last2=Raman |first2=Venkatesh |last3=Salowe |first3=Jeffrey S. |title=Stable in situ sorting and minimum data movement |journal=BIT |date=June 1990 |volume=30 |issue=2 |pages=220–234 |doi=10.1007/BF02017344 }} that is, does not exceed a constant no matter how large the input. Typically such an algorithm operates on data objects directly in place rather than making copies of them.

With big data, in situ data would mean bringing the computation to where data is located, rather than the other way like in traditional RDBMS systems where data is moved to computational space.{{Cite web|url=https://www.flashmemorysummit.com/English/Collaterals/Proceedings/2014/20140806_202E_Alves.pdf|title=In-Situ Processing Presentation|last=Alves|first=Vladimir|date=August 2014|access-date=24 May 2018|archive-date=28 November 2019|archive-url=https://web.archive.org/web/20191128024544/https://www.flashmemorysummit.com/English/Collaterals/Proceedings/2014/20140806_202E_Alves.pdf|url-status=live}} This is also known as in-situ processing.

In Earth sciences, particularly in geomorphology, in situ refers to natural materials or processes occurring at their point of origin without being transported. An example is weathering, in which rocks undergo physical or chemical disintegration in place,{{cite book |last=Twidale |first=C.R. |author-link=Charles Rowland Twidale |year=1968 |chapter=Weathering |editor-last=Fairbridge |editor-first=R.W. |title=Geomorphology |series=Encyclopedia of Earth Science |publisher=Springer Nature |location=Berlin, Heidelberg |doi=10.1007/3-540-31060-6_405 |quote=Weathering may be defined as the disintegration or decomposition of rocks in situ. [...] But the main mass of the rock remains in situ and is not transported. |page=1228 |isbn=0-442-00939-9 }} in contrast to erosion, which involves the removal and relocation of materials by agents such as wind, water, or ice.{{cite book |last=Thornbury |first=William David |chapter=3. An Analysis of the Geomorphic Processes |title=Principles of Geomorphology |year=1954 |publisher=Wiley |pages=36–37 |url=https://books.google.com/books?id=_ywtAAAAIAAJ |via=Google Books |oclc=1036826231 }} Soil formed from the weathering of underlying bedrock is an example of an in situ formation.{{cite book |last1=Troeh |first1=F.R. |last2=Donahue |first2=R.L. |title=Dictionary of Agricultural and Environmental Science |year=2003 |publisher=Iowa State Press |isbn=9780813802831 |url=https://books.google.com/books?id=doNtQgAACAAJ |via=Google Books }}{{rp|page=246}} In situ measurements, such as those of soil moisture, rock stress, groundwater trends, or radiation levels, are conducted on-site to provide direct data. These measurements are often essential for validating remote sensing data, such as satellite imagery, which is widely used for large-scale environmental monitoring but may require in situ confirmation to ensure accuracy.{{cite journal |last1=Pause |first1=Marion |last2=Schweitzer |first2=Christian |last3=Rosenthal |first3=Michael |last4=Keuck |first4=Vanessa |last5=Bumberger |first5=Jan |last6=Dietrich |first6=Peter |last7=Heurich |first7=Marco |last8=Jung |first8=András |last9=Lausch |first9=Angela |title=In Situ/Remote Sensing Integration to Assess Forest Health—A Review |journal=Remote Sensing |volume=8 |issue=6 |pages=471 |year=2016 |doi=10.3390/rs8060471 |doi-access=free |bibcode=2016RemS....8..471P }}{{cite journal |last1=Babaeian |first1=E. |last2=Sadeghi |first2=M. |last3=Jones |first3=S. B. |last4=Montzka |first4=C. |last5=Vereecken |first5=H. |last6=Tuller |first6=M. |year=2019 |title=Ground, proximal, and satellite remote sensing of soil moisture |journal=Reviews of Geophysics |volume=57 |issue=2 |pages=530–616 |doi=10.1029/2018RG000618 |doi-access=free |bibcode=2019RvGeo..57..530B }}{{cite journal |last1=Xiao |first1=R. |last2=He |first2=X. |last3=Zhang |first3=Y. |last4=Ferreira |first4=V. G. |last5=Chang |first5=L. |year=2015 |title=Monitoring Groundwater Variations from Satellite Gravimetry and Hydrological Models: A Comparison with in-situ Measurements in the Mid-Atlantic Region of the United States |journal=Remote Sensing |volume=7 |issue=1 |pages=686–703 |doi=10.3390/rs70100686 |doi-access=free |bibcode=2015RemS....7..686X }}

File:CTD-me-details hg.jpg, showing pressure housing, sensor cage, connectors, and internal electronics with sensors for conductivity, temperature, and pressure]]

In oceanography, in situ observational methods involve direct measurements of oceanic conditions, typically conducted during shipboard surveys. These methods employ specialized instruments, such as the Conductivity, Temperature, and Depth (CTD) device, which records parameters such as salinity, temperature, pressure, and biogeochemical properties like oxygen saturation.{{cite web |url=https://oceanexplorer.noaa.gov/technology/ctd/ctd.html |title=Conductivity, Temperature, and Depth (CTD) |website=NOAA Ocean Explorer |publisher=National Oceanic and Atmospheric Administration (NOAA) |access-date=21 February 2025 |archive-date=7 February 2025 |archive-url=https://web.archive.org/web/20250207080104/https://oceanexplorer.noaa.gov/technology/ctd/ctd.html |url-status=live }} Historically, oceanographers used reversing thermometers, which were inverted at specific depths to trap mercury and preserve temperature readings for subsequent analysis.{{cite book |last1=Affholder |first1=M. |last2=Valiron |first2=F. |title=Descriptive Physical Oceanography |chapter=Oceanographic Instruments and Methods |publisher=CRC Press |year=2001 |pages=61–63 |isbn=9780203969274 |url=https://books.google.com/books?id=2NC3JmKI7mYC |access-date=21 February 2025 |via=Google Books }} These instruments have been largely replaced by {{Abbr|CTD|Conductivity, Temperature, and Depth}} devices and expendable bathythermographs.{{Cite web |title=History: Timeline |website=NOAA Ocean Explorer |publisher=National Oceanic and Atmospheric Administration (NOAA) |url=https://oceanexplorer.noaa.gov/history/timeline/?page=3 |access-date=21 February 2025}}

{{Anchor|atmospheric science}}

In atmospheric sciences, in situ measurements refer to observations of atmospheric properties obtained using instruments placed within the environment being studied. Aircraft, balloons, and rockets are used to carry some of these instruments, allowing for direct interaction with the air to collect data.{{cite book |last=Robinson |first=Rod |editor1-last=Jackson |editor1-first=Andrea V. |editor2-last=Hewitt |editor2-first=C. Nick |chapter=Atmospheric Monitoring Techniques |title=Handbook of Atmospheric Science: Principles and Applications |edition=1st illustrated |date=2003 |page=464 |publisher=Wiley |isbn=9780632052868 |url=https://books.google.com/books?id=f51QCiiAWYQC |access-date=21 February 2025 |via=Google Books }} For example, radiosondes, carried aloft by weather balloons, measure atmospheric parameters such as temperature, humidity, and pressure as they ascend through the atmosphere,{{rp|page=396}} while anemometers, typically positioned at ground level or on towers, record wind speed and direction at specific locations.{{cite book |last1=Strahler |first1=Alan H. |title=Introducing Physical Geography |edition=6th |publisher=Wiley |year=2013 |isbn=978-111-839620-9 |page=156 |chapter=Chapter 5. Winds and Global Circulation }} In contrast, remote sensing techniques, such as weather radar and satellite observations, collect atmospheric data from a distance by using electromagnetic radiation to infer properties without direct contact with the atmosphere.{{cite journal |last1=Bluestein |first1=H. B. |last2=Carr |first2=F. H. |last3=Goodman |first3=S. J. |year=2022 |title=Atmospheric Observations of Weather and Climate |journal=Atmosphere-Ocean |publisher=Taylor & Francis |volume=60 |issue=3–4 |pages=149–187 |doi=10.1080/07055900.2022.2082369 |bibcode=2022AtO....60..149B }}

{{Further|In situ electron microscopy}}

By the mid-1980s, the term in situ was adopted in materials science, particularly in the field of heterogeneous catalysis, where a catalyst in one phase facilitates a chemical reaction in a different phase. The term later expanded beyond catalysis and is now applied across various disciplines of materials science, alongside the opposite designation ex situ.{{rp|page=1534}} For example, in situ describes the study of a sample maintained in a steady state{{efn|In sample characterization terminology, a system is in a steady state condition when one or more of its characteristics remain constant over time. This condition does not necessarily correspond to thermodynamic equilibrium.{{rp|page=1533}}}}

condition within a controlled environment, where specific parameters such as temperature or pressure are regulated. This approach allows researchers to observe materials under conditions that replicate their functional states. Examples include a sample held at a fixed temperature inside a cryostat, an electrode material operating within an electric battery, or a specimen enclosed within a sealed container to protect it from external influences.{{rp|page=1532}}

In transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), in situ refers to the observation of materials as they are exposed to external stimuli within the microscope, under conditions that mimic their natural environments. This enables real-time observation of material behavior at the nanoscale. External stimuli in in situ {{Abbr|TEM|Transmission electron microscopy}}/{{Abbr|STEM|Scanning transmission electron microscopy}} experiments may include mechanical loading, pressure, temperature variation, electrical biasing, radiation, and environmental exposure to gases, liquids, or magnetic fields, individually or in combination. These conditions allow researchers to study atomic-level processes—such as phase transformations, chemical reactions, or mechanical deformations—thereby providing insights into material properties and behavior essential for advances in materials science.{{cite book |doi=10.1002/9783527834822.ch1 |page=3 |title=In-Situ Transmission Electron Microscopy Experiments |chapter=Chapter 1. In-Situ TEM |date=2023 |last1=Sharma |first1=Renu |isbn=978-3-527-34798-8 }}{{cite journal |last1=Sharma |first1=Renu |last2=Yang |first2=Wei-Chang David |title=Perspective and prospects of in situ transmission/scanning transmission electron microscopy |journal=Microscopy |date=8 April 2024 |volume=73 |issue=2 |page=79 |doi=10.1093/jmicro/dfad057 |pmid=38006307 }}

{{anchor|cancer}}

{{Further|Carcinoma in situ}}

{{Seealso|List of medical roots, suffixes and prefixes}}

In medical terminology, in{{nbsp}}situ belongs to a group of two-word Latin expressions, including in vitro ('within the glass', e.g., laboratory experiments), in vivo ('within the living', e.g., experiments on living organisms), and ex vivo ('out of the living', e.g., experiments on extracted tissues), which facilitate communication of experimental or clinical contexts. Like abbreviations, these terms convey essential information concisely. In{{nbsp}}situ is a widely employed term in the medical field, used to describe phenomena or processes as they occur in their original location. It is applied in diverse contexts such as oncology, measurement acquisition, medical simulation, and anatomical examination. Because of its versatility across these varied applications, in{{nbsp}}situ is considered one of the most productive Latin expressions in contemporary medical discourse.{{cite journal | doi=10.1186/s13256-018-1562-x | doi-access=free | title=The use of Latin terminology in medical case reports: Quantitative, structural, and thematic analysis | date=2018 | last1=Lysanets | first1=Yuliia V. | last2=Bieliaieva | first2=Olena M. | journal=Journal of Medical Case Reports | volume=12 | issue=1 | page=45 | pmid=29471882 | pmc=5824564 }}

File:In situ carcinoma-en.svg, not having invaded beyond the basement membrane]]

In oncology, in situ is commonly applied in the context of carcinoma in situ (CIS), a term describing abnormal cells confined to their original location without invasion of surrounding tissue.{{cite encyclopedia |title=carcinoma in situ |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/carcinoma-in-situ |encyclopedia=NCI Dictionary of Cancer Terms |publisher=National Cancer Institute |access-date=2024-11-05 |archive-date=15 October 2024 |archive-url=https://web.archive.org/web/20241015055152/https://www.cancer.gov/publications/dictionaries/cancer-terms/def/carcinoma-in-situ |url-status=live }} The earliest known use of the term dates back to 1932 in the writing of U.S. surgical pathologist Albert C. Broders. Broders introduced both the term and the concept, and the concept of carcinoma in{{nbsp}}situ was initially controversial.{{cite journal |last=Wright |first=James R. Jr. |title=Albert C. Broders' paradigm shifts involving the prognostication and definition of cancer |journal=Archives of Pathology & Laboratory Medicine |date=2012 |volume=136 |issue=11 |pages=1437–1446 |doi=10.5858/arpa.2011-0567-HP |pmid=23106590 }} {{Abbr|CIS|Carcinoma in situ}} is a critical term in early cancer diagnosis, as it signifies a non-invasive stage, allowing for more targeted interventions such as localized excision or monitoring—before potential progression to invasive cancer.{{cite journal |last=Allred |first=D. C. |date=2010 |title=Ductal carcinoma in situ: terminology, classification, and natural history |journal=Journal of the National Cancer Institute Monographs |issue=41 |pages=134–138 |doi=10.1093/jncimonographs/lgq035|pmid=20956817 |pmc=5161057 }}{{cite journal | doi=10.1038/s41392-024-01779-3 | title=Progression from ductal carcinoma in situ to invasive breast cancer: Molecular features and clinical significance | date=2024 | last1=Wang | first1=Jing | last2=Li | first2=Baizhou | last3=Luo | first3=Meng | last4=Huang | first4=Jia | last5=Zhang | first5=Kun | last6=Zheng | first6=Shu | last7=Zhang | first7=Suzhan | last8=Zhou | first8=Jiaojiao | journal=Signal Transduction and Targeted Therapy | volume=9 | issue=1 | page=83 | pmid=38570490 | pmc=10991592 }} Melanoma in{{nbsp}}situ is an early, localized form of melanoma, a type of malignant skin cancer. In this stage, the cancerous melanocytes—the pigment-producing cells that give skin its color—are confined to the epidermis, the outermost layer of the skin. The melanoma has not yet penetrated into the deeper dermal layers or metastasized to other parts of the body.{{cite book|title=Histological Diagnosis of Nevi and Melanoma |url=https://books.google.com/books?id=G_zEBAAAQBAJ |first1=Guido |last1=Massi |first2=Philip E. |last2=LeBoit |year=2013 |via=Google Books |isbn=9783642373114 |publisher=Springer |page=421 |chapter=Chapter 28. Melanoma in Situ }}

Beyond oncology, in situ is used in fields where maintaining natural anatomical or physiological positions is essential. In orthopedic surgery, the term refers to procedures that preserve the natural alignment or position of bones or joints. For example, orthopedic plates or screws may be placed without altering the bone's original structure, as in "[the patient] was treated operatively with an in situ cannulated hip screw fixation".{{cite journal | doi=10.1186/1752-1947-6-136 | doi-access=free | title=A novel diagnostic sign of hip fracture mechanism in ground level falls: Two case reports and review of the literature | date=2012 | last1=Kelly | first1=Douglas W. | last2=Kelly | first2=Brian D. | journal=Journal of Medical Case Reports | volume=6 | page=136 | pmid=22643013 | pmc=3423009 }} In cardiothoracic surgery, in situ often describes techniques where blood vessels are utilized in their original anatomical position for surgical purposes. For example, the internal thoracic artery can be left attached to the subclavian artery while rerouting blood flow to bypass occluded coronary arteries and improve heart circulation.{{cite journal |last1=Fukui |first1=Toshihiro |last2=Takanashi |first2=Shuichiro |last3=Hosoda |first3=Yasuyuki |last4=Suehiro |first4=Shigefumi |title=In situ bilateral skeletonized internal thoracic arterial grafting for left-side myocardial revascularization using an off-pump technique |journal=Interactive CardioVascular and Thoracic Surgery |volume=5 |issue=4 |pages=413–417 |date=August 2006 |doi=10.1510/icvts.2006.128512 |pmid=17670604 |url=https://doi.org/10.1510/icvts.2006.128512 |access-date=23 February 2025}}{{cite journal |last1=Kawajiri |first1=Hidetake |last2=Grau |first2=Juan B |last3=Fortier |first3=Jacqueline H |last4=Glineur |first4=David |title=Bilateral internal thoracic artery grafting: in situ or composite? |journal=Annals of Cardiothoracic Surgery |volume=7 |issue=5 |pages=673–680 |date=September 2018 |doi=10.21037/acs.2018.05.16 |doi-access=free |pmc=6219951 |pmid=30505752 }} In organ transplantation, in situ is used to describe procedures performed within the donor's body to preserve organ viability. In situ perfusion is a technique employed during organ retrieval to restore blood flow to organs while they remain in their original location. This method minimizes ischemic injury and preserves organ viability for transplantation. In contrast, ex situ machine perfusion involves perfusing the organ outside the donor's body, typically after it has been removed.{{cite journal |last1=Jochmans |first1=I. |last2=Akhtar |first2=M. Z. |last3=Nasralla |first3=D. |last4=Kocabayoglu |first4=P. |last5=Boffa |first5=C. |last6=Kaisar |first6=M. |last7=Brat |first7=A. |last8=O'Callaghan |first8=J. |last9=Pengel |first9=L. H. M. |last10=Knight |first10=S. |last11=Ploeg |first11=R. J. |title=Past, Present, and Future of Dynamic Kidney and Liver Preservation and Resuscitation |journal=American Journal of Transplantation |volume=16 |issue=9 |pages=2545–2555 |date=September 2016 |doi=10.1111/ajt.13778 |pmid=26946212}}{{cite journal |last1=Reznik |first1=O. |last2=Skvortsov |first2=A. |last3=Loginov |first3=I. |last4=Ananyev |first4=A. |last5=Bagnenko |first5=S. |last6=Moysyuk |first6=Y. |title=Kidney from uncontrolled donors after cardiac death with one hour warm ischemic time: resuscitation by extracorporal normothermic abdominal perfusion "in situ" by leukocytes-free oxygenated blood |journal=Clinical Transplantation |volume=25 |issue=4 |pages=511–516 |date=July–August 2011 |doi=10.1111/j.1399-0012.2010.01333.x |pmid=20626704}}{{efn|See ex vivo.}}

{{Further|Steam-assisted gravity drainage}}

In petroleum engineering, in situ techniques involve the application of heat or solvents to extract heavy crude oil or bitumen from reservoirs located beneath the Earth's surface. Several in situ methods exist, but those that utilize heat, particularly steam, have proven to be the most effective for oil sands extraction. The most widely used in situ technique is steam-assisted gravity drainage (SAGD).{{cite web |title=Oil Sands Extraction and Processing |url=https://natural-resources.canada.ca/energy-sources/fossil-fuels/oil-sands-extraction-processing |url-status=live |archive-url=https://web.archive.org/web/20250303185847/https://natural-resources.canada.ca/energy-sources/fossil-fuels/oil-sands-extraction-processing |website=Natural Resources Canada |date=16 January 2025 |archive-date=3 March 2025 |access-date=3 March 2025 }} This method employs two horizontal wells: the upper well injects steam to heat the bitumen, reducing its viscosity, while the lower well collects the mobilized oil for extraction.{{cite web |last1=Ahtian |first1=Sourabh |last2=Irani |first2=Mazda |last3=de Haas |first3=Tom |last4=Abedini |first4=Ali |title=In Situ Methods for Bitumen Extraction: An Overview |url=https://www.interfacefluidics.com/in-situ-methods-for-bitumen-extraction-an-overview/ |website=Interface Fluidics |access-date=3 March 2025 |archive-date=3 November 2024 |archive-url=https://web.archive.org/web/20241103041805/https://www.interfacefluidics.com/in-situ-methods-for-bitumen-extraction-an-overview/ |url-status=live }} {{Abbr|SAGD|Steam-assisted gravity drainage}} has gained prominence in the Canadian province of Alberta, due to its efficiency in recovering bitumen from deep reservoirs. Approximately 80% of Alberta's oil sands deposits are located at depths that render open-pit mining impractical, making in situ techniques such as {{Abbr|SAGD|Steam-assisted gravity drainage}} the primary method of extraction.{{cite web | title = Steam Assisted Gravity Drainage: Facts and Stats | url = https://open.alberta.ca/dataset/f7c779ea-9776-4d59-a1b3-178d533f0ebc/resource/aac73d46-3ae0-478e-9b19-e64afa41b1f2/download/fssagd.pdf |website = open.alberta.ca | publisher = Government of Alberta |date=November 2013 |access-date = 24 February 2025 |archive-url=https://web.archive.org/web/20240304205256/https://open.alberta.ca/dataset/f7c779ea-9776-4d59-a1b3-178d533f0ebc/resource/aac73d46-3ae0-478e-9b19-e64afa41b1f2/download/fssagd.pdf |archive-date=4 March 2024 }}

In urban planning, in situ upgrading is an approach to and method of upgrading informal settlements.{{cite journal|last1=Huchzermeyer|first1=Marie|title=The struggle for in situ upgrading of informal settlements: A reflection on cases in Gauteng|journal=Development Southern Africa |date=2009|volume=26|issue=1|pages=59–74|doi=10.1080/03768350802640099|s2cid=153687182}}

File:Hohokam Arrowhead Sahuarita Arizona 2014.jpg arrowhead in situ]]

In archaeology, the term in situ has been used variably to describe artifacts or features discovered in a presumed original context, yet its precise definition remains contested. Scholars distinguish between a broad usage—denoting materials recovered through controlled excavation—and a stricter usage reserved for those found in undisturbed, primary depositional settings. Between these poles lies a continuum of depositional scenarios, from sealed habitation floors to slope or fluvial deposits, meaning that whether an object is truly in situ depends on site-specific formation processes and the degree to which stratigraphic as well as spatial relationships can be reconstructed.{{cite journal |last1=Archer |first1=Will |last2=Aldeias |first2=Vera |last3=McPherron |first3=Shannon P. |title=What is 'in situ'? A reply to Harmand et al. (2015) |journal=Journal of Human Evolution |date=2020 |volume=142 |doi=10.1016/j.jhevol.2020.102740 |pmid=32247106 |bibcode=2020JHumE.14202740A }} Recording the exact spatial coordinates, stratigraphic position, and surrounding matrix of depositional materials is necessary for understanding past human activities and historical processes. While artifacts are often removed for analysis, certain archaeological features—such as hearths, postholes, and architectural foundations—have to be thoroughly documented in place to preserve their contextual information during excavation.{{cite book |title=Archaeology: Theories, Methods and Practice |first1=Colin |last1=Renfrew |author-link1=Colin Renfrew |first2=Paul |last2=Bahn |date=2020 |author-link2=Paul Bahn |isbn=978-0-500-29424-6 |edition=8th |publisher=Thames & Hudson |location=London }}{{rp|page=121}} This documentation relies on various methods, including detailed field notes, scaled technical drawings, cartographic representation, and high-resolution photographic records. Current archaeological practice incorporates advanced digital technologies, including 3D laser scanning, photogrammetry, unmanned aerial vehicles, and Geographic Information Systems (GIS), to capture complex spatial relationships.{{Cite journal|title=An Innovative System for Enhancing Archaeological In Situ Excavation through Geospatial Integration|first1=Asimina|last1=Dimara|first2=Sotirios|last2=Tsakiridis|first3=Doukas|last3=Psarros|first4=Alexios|last4=Papaioannou|first5=Dimitrios|last5=Varsamis|first6=Christos-Nikolaos|last6=Anagnostopoulos|first7=Stelios|last7=Krinidis|date=24 May 2024 |journal=Heritage|volume=7|issue=5|pages=2586–2619|doi=10.3390/heritage7050124 |doi-access=free }} Artifacts found outside their original context or ex situ, often due to natural disturbances or unrecorded excavations, have less interpretive value. However, these displaced materials can still provide clues about the spatial distribution and typological characteristics of unexcavated in situ deposits, guiding future excavation efforts.{{Cite web|url=https://archdenk.rkarl.org/2019/01/an-empirical-examination-of.html?m=1 |archive-url=https://web.archive.org/web/20240511051111/https://archdenk.rkarl.org/2019/01/an-empirical-examination-of.html?m=1 |archive-date=11 May 2024 |title=An empirical examination of archaeological damage caused by unprofessional extraction of archaeology ex situ ('looting'): A case study from Austria |first=Raimund |last=Karl |author-link=Raimund Karl |date=2 January 2019 |publisher=Archäologische Denkmalpflege |pages=1–2 |access-date=2024-10-24 }}{{Cite journal|title=Coastal curios? An analysis of ex situ beach finds for mapping new Palaeolithic sites at Happisburgh, UK|first1=Rachel|last1=Bynoe|first2=Nick M.|last2=Ashton|first3=Tim|last3=Grimmer|first4=Peter|last4=Hoare|first5=Joanne|last5=Leonard|first6=Simon G.|last6=Lewis|first7=Darren|last7=Nicholas|first8=Simon|last8=Parfitt|date=February 24, 2021|journal=Journal of Quaternary Science |volume=36|issue=2|pages=191–210|doi=10.1002/jqs.3270|bibcode=2021JQS....36..191B |doi-access=free}}

The Convention on the Protection of the Underwater Cultural Heritage sets mandatory guidelines for signatory states regarding the treatment of underwater shipwrecks. One of its key principles is that in situ preservation is the preferred approach.{{rp|page=558}}{{cite web |title=The UNESCO Convention on the Protection of the Underwater Cultural Heritage |url=https://unesdoc.unesco.org/ark:/48223/pf0000152883 |year=2007 |access-date=2024-10-12 |website=UNESCO Digital Library |publisher=UNESCO |archive-date=28 August 2024 |archive-url=https://web.archive.org/web/20240828104155/https://unesdoc.unesco.org/ark:/48223/pf0000152883 |url-status=live }}{{rp|page=13}} This policy is based on the unique conditions of underwater environments, where low oxygen levels and stable temperatures help preserve artifacts over long periods. Removing artifacts from these conditions and exposing them to the atmosphere often accelerates deterioration, particularly the oxidation of iron-based materials.{{rp|page=5}}

In mortuary archaeology, in situ documentation involves systematically recording and cataloging human remains in their original depositional positions. These remains are often embedded in complex matrices of sediment, clothing, and associated artifacts. Excavating mass graves presents additional challenges, as they may contain hundreds of individuals. Before identifying individuals or determining causes of death, archaeologists must carefully document spatial relationships and contextual details to preserve forensic and historical information.{{cite journal |last1=Tuller |first1=Hugh |last2=Đurić’ |first2=Marija |title=Keeping the pieces together: Comparison of mass grave excavation methodology |journal=Forensic Science International |date=January 2006 |volume=156 |issue=2–3 |page=193 |doi=10.1016/j.forsciint.2004.12.033 |pmid=15896937 }}

{{Further|Site-specific art|Land art}}

{{Broader|Installation art}}

File:"The Mastaba" massive sculpture, floating in the Serpentine (geograph 5815024).jpg's temporary installations, such as The London Mastaba (pictured), exemplify in situ approach in art.]]

The concept of in situ in contemporary art emerged as a framework in the late 1960s and 1970s, referring to artworks created specifically for a particular space. These works integrate the site's physical, historical, political, and sociological characteristics as essential elements of their composition.{{rp|pages=160–162}} This approach contrasts with autonomous artistic production, where artworks are independent of their eventual display locations.{{cite encyclopedia|encyclopedia=Dictionary of Untranslatables: A Philosophical Lexicon |editor-first=Barbara |editor-last=Cassin |editor-link=Barbara Cassin |title=IN SITU (LATIN) |last=Riout |first=Denys |date=9 February 2014 |publisher=Princeton University Press |page=484 |isbn=9781400849918 }} Theoretical discussions, particularly in the writings and practice of French conceptual artist and sculptor Daniel Buren, have emphasized the dynamic relationship between artistic intervention and its surrounding environment.{{cite book|title=Arts, Ecologies, Transitions: Constructing a Common Vocabulary |first=Lorraine |last=Verner |editor-last1=Barbanti |editor-first1=Roberto |editor-last2=Ginot |editor-first2=Isabelle |editor-last3=Solomos |editor-first3=Makis |editor-last4=Sorin |editor-first4=Cécile |chapter=40. Site Specificity |isbn=9781003852407 |publisher=Taylor & Francis |year=2024 |url=https://books.google.com/books?id=J2fwEAAAQBAJ |via=Google Books |access-date=2024-10-24 }}{{rp|page=161}}

The site-specific installations of Christo and Jeanne-Claude exemplify the application of in situ principles in art. Their large-scale interventions such as The Pont Neuf Wrapped (1985) and Wrapped Reichstag (1995) involved the systematic wrapping of buildings and landscape elements in fabric, temporarily transforming familiar spaces and altering public perception. The concept of in situ art further evolved with the land art movement, wherein artists such as Robert Smithson and Michael Heizer integrated their works directly into natural landscapes and created an inseparable connection between the artwork and its environment. In contemporary aesthetic discourse, in situ has expanded into a broader theoretical construct, describing artistic practices that reinforce the fundamental unity between a work and its site.{{rp|pages=160–161}}

{{Seealso|Situs (law)}}

In legal contexts, in situ is often used for its literal sense, meaning 'in its original place'. In Hong Kong, in-situ land exchange refers to a mechanism whereby landowners can swap their existing or expired land leases for new grants covering the same land parcel. This approach facilitates redevelopment—such as modernizing buildings or increasing land usage density—in a crowded, land-scarce environment without displacing ownership from the original location. The Hong Kong government, through the Development Bureau and Lands Department, has implemented arrangements to expedite lease modifications and land exchanges.{{cite journal|last= Fong | first = Peter K. W. | title = Issues in Urban Redevelopment: The Land Development Corporation | journal = Built Environment | volume = 11 | issue = 4 | year = 1985 |pages= 283–293 |publisher=Alexandrine Press |jstor = 23286194 }}{{rp|pages=283–285}}{{Cite web|url=https://www.devb.gov.hk/en/publications_and_press_releases/press/index_id_12712.html |archive-url=https://web.archive.org/web/20250122025215/https://www.devb.gov.hk/en/publications_and_press_releases/press/index_id_12712.html |archive-date=22 January 2025 |url-status=live |title=DEVB Press Releases: Revised in-situ land exchange arrangements for Northern Metropolis to enhance speed and efficiency by leveraging market forces |website=devb.gov.hk |year=2021 |access-date=6 November 2024 |publisher=Development Bureau }}{{cite web |title=In-situ land exchange to enable harbourfront development at Quarry Bay by private lot owner |url=https://www.info.gov.hk/gia/general/202103/03/P2021030300443.htm |publisher=The Government of the Hong Kong Special Administrative Region |date=3 March 2021 |access-date=3 March 2025 |archive-date=30 December 2022 |archive-url=https://web.archive.org/web/20221230205956/https://www.info.gov.hk/gia/general/202103/03/P2021030300443.htm |url-status=live }}

In public international law, the term in situ is used to distinguish between a government that exercises effective control over a state's territory and population and a government-in-exile, which operates from outside its national borders. A government in situ is the de facto governing authority, while a government-in-exile may still claim legitimacy despite lacking territorial control. The recognition of a government generally depends on its ability to maintain authority over its state, though exceptions exist, particularly when a government-in-exile is displaced due to unlawful foreign occupation.{{cite book |last=Pavlopoulos |first=Niko |chapter=The International Legal Criteria for Governmental Status |title=The Identity of Governments in International Law |date=2024 |pages=94–141 |chapter-url=https://www.ilsa.org/Jessup/Jessup2025/Basic%20Materials/Chapter%204.pdf |url-status=live |archive-url=https://web.archive.org/web/20241005031527/https://www.ilsa.org/Jessup/Jessup2025/Basic%20Materials/Chapter%204.pdf |archive-date=5 October 2024 |publisher=Oxford University Press |doi= 10.1093/9780191991509.003.0004 |isbn=978-0-19-199150-9 |via=www.ilsa.org |access-date=3 March 2025}}{{rp|pages=115–117}}{{cite book |last=Talmon |first=Stefan |author-link=Stefan Talmon |title=Recognition of Governments in International Law: With Particular Reference to Governments in Exile |series=Oxford Monographs in International Law |year=2001 |chapter=Preliminary Considerations |publisher=Oxford University Press |isbn=978-0-19-924839-1}}{{rp|page=2}}

{{Broader|English interrogative words}}

In linguistics, particularly in syntax, an element is described as in situ when it is pronounced in the same position where it receives its semantic interpretation. This concept is especially relevant in the analysis of wh- questions across languages. For example, in Mandarin Chinese and Kurdish, wh-elements remain in situ, producing structures analogous to "John bought what?" where the interrogative word occupies the same syntactic position as the direct object would in a declarative sentence ("John bought bread").{{Cite journal |last = Liu |first = Chi-Ming Louis | date = January 2023 | title = (Embedded) short answers to wh-questions in Mandarin Chinese | journal = Journal of East Asian Linguistics | volume = 31 | issue = 3 | pages = 351–399 | doi = 10.1007/s10831-022-09242-6 }}{{Cite journal | last = Toma | first = Shivan | date = March 2020 | title = From Wh-Movement to Wh-In-Situ Acquisition of I-To-C Movement in English Interrogative Constructions by Kurdish Learners | journal = Humanities Journal of University of Zakho | volume = 8 | issue = 1 | pages = 159–171 | doi = 10.26436/hjuoz.2020.8.1.585 | doi-access = free }} By contrast, languages like English and French typically employ wh-movement, where the interrogative element is displaced from its base position to the beginning of the clause, as in "What did John buy?" Here, the wh-word {{linktext|what}} has moved from its original post-verbal position to the sentence-initial position, leaving behind a trace or gap in the object position. This typological distinction between in situ wh-elements and moved wh-elements represents one of the fundamental parameters of variation in natural language syntax and has been extensively studied within generative grammar frameworks.

In economics, in situ storage refers to the practice of retaining a product, usually a natural resource, in its original location rather than extracting and storing it elsewhere. This method avoids direct out-of-pocket costs, such as those for transportation or storage facilities, with the primary expense being the opportunity cost of delaying potential revenue. It applies to resources like oil and gas left unextracted in wells, minerals and gemstones remaining underground, and timber left standing until extraction is economically favorable. Certain agricultural products, such as hay, can be stored in situ under suitable conditions.{{cite book |last=Dorfman |first=Jeffrey |chapter=5. The economics of storage |title=Economics and Management of the Food Industry |series=Routledge Textbooks in Environmental and Agricultural Economics |publisher=Routledge |year=2014 |isbn=9781134456567 |url=https://books.google.com/books?id=b-4jAwAAQBAJ |via=Google Books |access-date=3 March 2025 }}{{rp|page=54}}{{cite book |last1=Barbosa-Cánovas |first1=Gustavo V. |author-link1=Gustavo V. Barbosa-Cánovas |last2=Fernández-Molina |first2=Juan J. |last3=Alzamora |first3=Stella M. |last4=Tapia |first4=Maria S. |last5=López-Malo |first5=Aurelio |title=Handling and Preservation of Fruits and Vegetables by Combined Methods for Rural Areas |url=https://books.google.com/books?id=IKsaRY9sb_AC |publisher=Food and Agriculture Organization of the United Nations |year=2003 |isbn=9789251048610 |via=Google Books |access-date=3 March 2025 }}{{rp|page=35}}

In psychology, in situ typically refers to studies conducted in a natural or real-world setting, as opposed to a controlled laboratory environment. This approach allows researchers to observe and measure psychological processes as they occur, increasing ecological validity—though often at the expense of experimental control over variables.{{cite book |last=Stevenson |first=Andrew |year=2010 |title=Cultural Issues in Psychology: A Student's Handbook |publisher=Routledge |isbn=9781135239848 |url=https://books.google.com/books?id=1cCNAgAAQBAJ |access-date=4 March 2025 |via=Google Books }}{{rp|pages=84–85}}

In gastronomy, in situ refers to the art of cooking with the different resources that are available at the site of the event. Here a person is not going to the restaurant, but the restaurant comes to the person's home.{{cite book|last1=Gillespie|first1=Cailein|last2=Cousins|first2=John A.|title=European Gastronomy into the 21st Century|date=2001|publisher=Elsevier|location=Oxford, UK|isbn=978-0-7506-5267-4|pages=72|url=https://books.google.com/books?id=2G5cihKVlOIC&q=in+situ+gastronomy&pg=PA72|access-date=16 June 2014}}

{{Main|In situ leach}}

In situ leaching or in situ recovery refers to the mining technique of injecting lixiviant underground to dissolve ore and bringing the pregnant leach solution to surface for extraction. Commonly used in uranium mining but has also been used for copper mining.{{cite web |url=http://www.world-nuclear.org/info/inf27.html |title=In Situ Leach (ISL) Mining of Uranium |website=World Nuclear Association |publisher=world-nuclear.org |date=March 2008 |archive-url=https://web.archive.org/web/20090424213134/http://www.world-nuclear.org/info/inf27.html |archive-date=24 April 2009 |access-date=19 February 2025}}

{{Wiktionary}}

• In situ conservation
• Ex situ conservation
• List of colossal sculptures in situ
• List of Latin phrases
• {{annotated link|Neoclassical compound}}
• {{lookfrom}}

{{notelist}}

{{reflist}}

{{Reflist|group=†}}

Category:Latin words and phrases

Category:Latin legal terminology

Category:Latin biological phrases

Category:Latin medical words and phrases

Category:Animal test conditions

Category:Scientific terminology