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class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Causes of <i>δ</i><sup>13</sup>C variations</span> </div> </a> <ul id="toc-Causes_of_δ13C_variations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Geologic_significance" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Geologic_significance"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Geologic significance</span> </div> </a> <button aria-controls="toc-Geologic_significance-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Geologic significance subsection</span> </button> <ul id="toc-Geologic_significance-sublist" class="vector-toc-list"> <li id="toc-Positive_and_negative_excursions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Positive_and_negative_excursions"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Positive and negative excursions</span> </div> </a> <ul id="toc-Positive_and_negative_excursions-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lacustrine_environments" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Lacustrine_environments"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Lacustrine environments</span> </div> </a> <ul id="toc-Lacustrine_environments-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Major_excursion_events" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Major_excursion_events"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Major excursion events</span> </div> </a> <ul id="toc-Major_excursion_events-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> 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class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><i>δ</i><sup>13</sup>C</h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. 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German" lang="de" hreflang="de" data-title="Δ13C" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/%CE%9413C" title="Δ13C – Spanish" lang="es" hreflang="es" data-title="Δ13C" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/%CE%9413C" title="Δ13C – French" lang="fr" hreflang="fr" data-title="Δ13C" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/%CE%9413C" title="Δ13C – Indonesian" lang="id" hreflang="id" data-title="Δ13C" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/%CE%9413C" title="Δ13C – Portuguese" lang="pt" hreflang="pt" data-title="Δ13C" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%CE%9413C" title="Δ13C – Russian" lang="ru" hreflang="ru" data-title="Δ13C" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/%CE%9413C" title="Δ13C – Finnish" lang="fi" hreflang="fi" data-title="Δ13C" data-language-autonym="Suomi" data-language-local-name="Finnish" 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src="//upload.wikimedia.org/wikipedia/commons/thumb/1/10/Benthic_foraminifera.jpg/200px-Benthic_foraminifera.jpg" decoding="async" width="200" height="194" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/10/Benthic_foraminifera.jpg/300px-Benthic_foraminifera.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/10/Benthic_foraminifera.jpg/400px-Benthic_foraminifera.jpg 2x" data-file-width="427" data-file-height="414" /></a><figcaption><a href="/wiki/Foraminifera" title="Foraminifera">Foraminifera</a> samples</figcaption></figure> <p>In <a href="/wiki/Geochemistry" title="Geochemistry">geochemistry</a>, <a href="/wiki/Paleoclimatology" title="Paleoclimatology">paleoclimatology</a>, and <a href="/wiki/Paleoceanography" title="Paleoceanography">paleoceanography</a> <b><i>δ</i><sup>13</sup>C</b> (pronounced "delta thirteen c") is an <a href="/wiki/Isotopic_signature" title="Isotopic signature">isotopic signature</a>, a measure of the ratio of the two <a href="/wiki/Stable_isotope" class="mw-redirect" title="Stable isotope">stable isotopes</a> of <a href="/wiki/Carbon" title="Carbon">carbon</a>—<a href="/wiki/Carbon-13" title="Carbon-13"><sup>13</sup>C</a> and <a href="/wiki/Carbon-12" title="Carbon-12"><sup>12</sup>C</a>—reported in <a href="/wiki/Parts_per_thousand" class="mw-redirect" title="Parts per thousand">parts per thousand</a> (per mil, ‰).<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The measure is also widely used in archaeology for the reconstruction of past diets, particularly to see if marine foods or certain types of plants were consumed.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The definition is, in <a href="/wiki/Per_mille" title="Per mille">per mille</a>: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \delta {\ce {^{13}C}}=\left({\frac {({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {sample} }}{({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {standard} }}}-1\right)\times 1000}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>δ</mi> <mrow class="MJX-TeXAtom-ORD"> <mmultiscripts> <mtext>C</mtext> <none></none> <none></none> <mprescripts></mprescripts> <none></none> <mn>13</mn> </mmultiscripts> </mrow> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mmultiscripts> <mtext>C</mtext> <none></none> <none></none> <mprescripts></mprescripts> <none></none> <mn>13</mn> </mmultiscripts> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mmultiscripts> <mtext>C</mtext> <none></none> <none></none> <mprescripts></mprescripts> <none></none> <mn>12</mn> </mmultiscripts> </mrow> <msub> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">p</mi> <mi mathvariant="normal">l</mi> <mi mathvariant="normal">e</mi> </mrow> </mrow> </msub> </mrow> <mrow> <mo stretchy="false">(</mo> <mrow class="MJX-TeXAtom-ORD"> <mmultiscripts> <mtext>C</mtext> <none></none> <none></none> <mprescripts></mprescripts> <none></none> <mn>13</mn> </mmultiscripts> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mmultiscripts> <mtext>C</mtext> <none></none> <none></none> <mprescripts></mprescripts> <none></none> <mn>12</mn> </mmultiscripts> </mrow> <msub> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">s</mi> <mi mathvariant="normal">t</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">d</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">d</mi> </mrow> </mrow> </msub> </mrow> </mfrac> </mrow> <mo>−</mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> <mo>×</mo> <mn>1000</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \delta {\ce {^{13}C}}=\left({\frac {({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {sample} }}{({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {standard} }}}-1\right)\times 1000}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ad4a2fc51a8f08aebed2a6cac104da521542659d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.171ex; width:40.168ex; height:7.509ex;" alt="{\displaystyle \delta {\ce {^{13}C}}=\left({\frac {({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {sample} }}{({\ce {^{13}C}}/{\ce {^{12}C}})_{\mathrm {standard} }}}-1\right)\times 1000}" /></span></dd></dl> <p>where the standard is an established <a href="/wiki/Reference_materials_for_stable_isotope_analysis" title="Reference materials for stable isotope analysis">reference material</a>. </p><p><i>δ</i><sup>13</sup>C varies in time as a function of productivity, the signature of the inorganic source, <a href="/wiki/Oceanic_carbon_cycle#Burial" title="Oceanic carbon cycle">organic carbon burial</a>, and vegetation type. Biological processes preferentially take up the lower mass <a href="/wiki/Isotope" title="Isotope">isotope</a> through <a href="/wiki/Kinetic_fractionation" title="Kinetic fractionation">kinetic fractionation</a>. However some abiotic processes do the same. For example, <a href="/wiki/Methane" title="Methane">methane</a> from hydrothermal vents can be depleted by up to 50%.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Reference_standard">Reference standard</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=1" title="Edit section: Reference standard"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The standard established for carbon-13 work was the Pee Dee Belemnite (PDB) and was based on a <a href="/wiki/Cretaceous" title="Cretaceous">Cretaceous</a> marine fossil, <i><a href="/wiki/Belemnitella_americana" class="mw-redirect" title="Belemnitella americana">Belemnitella americana</a></i>, which was from the <a href="/wiki/Peedee_Formation" title="Peedee Formation">Peedee Formation</a> in <a href="/wiki/South_Carolina" title="South Carolina">South Carolina</a>. This material had an anomalously high <sup>13</sup>C:<sup>12</sup>C ratio (0.0112372<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>), and was established as <i>δ</i><sup>13</sup>C value of zero. </p><p>Since the original PDB specimen is no longer available, its <sup>13</sup>C:<sup>12</sup>C ratio can be back-calculated from a widely measured carbonate standard NBS-19, which has a <i>δ</i><sup>13</sup>C value of +1.95‰.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The <sup>13</sup>C:<sup>12</sup>C ratio of NBS-19 was reported as <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 0.011078/0.988922=0.011202}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>0.011078</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mn>0.988922</mn> <mo>=</mo> <mn>0.011202</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 0.011078/0.988922=0.011202}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d1fd0376c4ada0b08d4499b5408c750ade1eda22" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:30.613ex; height:2.843ex;" alt="{\displaystyle 0.011078/0.988922=0.011202}" /></span>.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Therefore, one could calculate the <sup>13</sup>C:<sup>12</sup>C ratio of PDB derived from NBS-19 as <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 0.011202/(1.95/1000+1)=0.011202/1.00195=0.01118}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>0.011202</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mo stretchy="false">(</mo> <mn>1.95</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mn>1000</mn> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> <mo>=</mo> <mn>0.011202</mn> <mrow class="MJX-TeXAtom-ORD"> <mo>/</mo> </mrow> <mn>1.00195</mn> <mo>=</mo> <mn>0.01118</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 0.011202/(1.95/1000+1)=0.011202/1.00195=0.01118}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2d8263bffe466026ef258d5f2827f1886be0e76b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:57.092ex; height:2.843ex;" alt="{\displaystyle 0.011202/(1.95/1000+1)=0.011202/1.00195=0.01118}" /></span>. </p><p>Note that this value differs from the widely used PDB <sup>13</sup>C:<sup>12</sup>C ratio of 0.0112372 used in isotope forensics<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> and environmental scientists;<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> this discrepancy was previously attributed by a Wikipedia author to a sign error in the interconversion between standards, but no citation was provided. Use of the PDB standard gives most natural material a negative <i>δ</i><sup>13</sup>C.<sup id="cite_ref-UGa_9-0" class="reference"><a href="#cite_note-UGa-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> A material with a ratio of 0.010743 for example would have a <i>δ</i><sup>13</sup>C value of −44‰ from <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (0.010743\div 0.01124-1)\times 1000}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mo stretchy="false">(</mo> <mn>0.010743</mn> <mo>÷</mo> <mn>0.01124</mn> <mo>−</mo> <mn>1</mn> <mo stretchy="false">)</mo> <mo>×</mo> <mn>1000</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle (0.010743\div 0.01124-1)\times 1000}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/9d5852b63555094d9f9cb7e7f4f6a3b680a2892d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:32.548ex; height:2.843ex;" alt="{\displaystyle (0.010743\div 0.01124-1)\times 1000}" /></span>. </p><p>The standards are used for verifying the accuracy of <a href="/wiki/Mass_spectroscopy" class="mw-redirect" title="Mass spectroscopy">mass spectroscopy</a>; as isotope studies became more common, the demand for the standard exhausted the supply. Other standards calibrated to the same ratio, including one known as VPDB (for "Vienna PDB"), have replaced the original.<sup id="cite_ref-BO_186_10-0" class="reference"><a href="#cite_note-BO_186-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> The <sup>13</sup>C:<sup>12</sup>C ratio for VPDB, which the <a href="/wiki/International_Atomic_Energy_Agency" title="International Atomic Energy Agency">International Atomic Energy Agency</a> (IAEA) defines as a <i>δ</i><sup>13</sup>C value of zero is 0.01123720.<sup id="cite_ref-IAEA_11-0" class="reference"><a href="#cite_note-IAEA-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Causes_of_δ13C_variations"><span id="Causes_of_.CE.B413C_variations"></span>Causes of <i>δ</i><sup>13</sup>C variations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=2" title="Edit section: Causes of δ13C variations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Methane has a very light <i>δ</i><sup>13</sup>C signature: biogenic methane of −60‰, thermogenic methane −40‰. The release of large amounts of <a href="/wiki/Methane_clathrate" title="Methane clathrate">methane clathrate</a> can affect global <i>δ</i><sup>13</sup>C values, as at the <a href="/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum" title="Paleocene–Eocene Thermal Maximum">Paleocene–Eocene Thermal Maximum</a>.<sup id="cite_ref-Panchuk2008_12-0" class="reference"><a href="#cite_note-Panchuk2008-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p><p>More commonly, the ratio is affected by variations in <a href="/wiki/Primary_productivity" class="mw-redirect" title="Primary productivity">primary productivity</a> and organic burial. Organisms preferentially take up light <sup>12</sup>C, and have a <i>δ</i><sup>13</sup>C signature of about −25‰, depending on their <a href="/wiki/Metabolic_pathway" title="Metabolic pathway">metabolic pathway</a>. Therefore, an increase in <i>δ</i><sup>13</sup>C in marine fossils is indicative of an increase in the abundance of vegetation.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2019)">citation needed</span></a></i>]</sup> </p><p>An increase in primary productivity causes a corresponding rise in <i>δ</i><sup>13</sup>C values as more <sup>12</sup>C is locked up in plants. This signal is also a function of the amount of carbon burial; when organic carbon is buried, more <sup>12</sup>C is locked out of the system in sediments than the background ratio. </p> <div class="mw-heading mw-heading2"><h2 id="Geologic_significance">Geologic significance</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=3" title="Edit section: Geologic significance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/C3_carbon_fixation" title="C3 carbon fixation">C<sub>3</sub></a> and <a href="/wiki/C4_carbon_fixation" title="C4 carbon fixation">C<sub>4</sub></a> plants have different signatures, allowing the abundance of C<sub>4</sub> grasses to be detected through time in the <i>δ</i><sup>13</sup>C record.<sup id="cite_ref-Retallack2001_13-0" class="reference"><a href="#cite_note-Retallack2001-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Whereas C<sub>4</sub> plants have a <i>δ</i><sup>13</sup>C of −16 to −10‰, C<sub>3</sub> plants have a <i>δ</i><sup>13</sup>C of −33 to −24‰.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Positive_and_negative_excursions">Positive and negative excursions</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=4" title="Edit section: Positive and negative excursions"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Positive <i>δ</i><sup>13</sup>C excursions are interpreted as an increase in burial of organic carbon in sedimentary rocks following either a spike in primary productivity, a drop in decomposition under anoxic ocean conditions or both.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> For example, the <a href="/wiki/Evolution_of_plants#Evolution_of_trees" class="mw-redirect" title="Evolution of plants">evolution of large land plants</a> in the late <a href="/wiki/Devonian" title="Devonian">Devonian</a> led to increased organic carbon burial and consequently a rise in <i>δ</i><sup>13</sup>C.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p><p>Negative <i>δ</i><sup>13</sup>C anomalies, which are thought to represent a decrease in primary productivity and release of plant-based carbon, often mark <a href="/wiki/Mass_extinction" class="mw-redirect" title="Mass extinction">mass extinctions</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Lacustrine_environments">Lacustrine environments</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=5" title="Edit section: Lacustrine environments"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Other important applications of <i>δ</i><sup>13</sup>C involves understanding its signatures from soft sediments especially in lacustrine environments. This depends on the system from which it is extracted (open system, closed system, etc.). Temporal variations in <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> in organic matter are influenced by diverse internal and external processes:<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p> <ol><li>Changes in the Dominant Source of Dissolved Inorganic Carbon: In stratified lakes, the accumulation of 13C-depleted carbon in deep water is common as sinking and degrading phytoplankton cells contribute to this pool. Recirculating this water to the surface can lead to a significant decrease in <span class="texhtml">δ</span><sup>13</sup>C<sub></sub>. Prolonged stratification enriches the dissolved inorganic carbon (DIC) pool in the epilimnion with 13C. Long-term variations in factors affecting upwelling intensity or depth, such as windiness, water temperature, or salinity-related stratification, manifest as shifts between more negative and positive <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> values.</li> <li>Changes in Productivity/Eutrophication: Increased productivity accelerates the transfer of organic matter with negative <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> values to the hypolimnion, affecting the <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> of residual epilimnetic DIC. This impact, combined with mixing effects, results in variations in the <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> signal.</li> <li>Changes in Metabolic Pathways for Carbon Fixation: Major changes in lake alkalinity influence benthic and planktonic primary production. Shifts in the dominant source of DIC for photosynthesis, driven by pH changes, can lead to trends toward more positive <span class="texhtml">δ</span><sup>13</sup>C<sub></sub>, particularly in lakes dominated by autochthonous organic matter and exhibiting evidence of high alkalinity.</li> <li>Changes in Availability of Dissolved CO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub>: Cool water can dissolve higher concentrations of CO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub> than warmer water, affecting <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> in organic matter during cooling events. Changes in atmospheric CO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub> concentrations also influence <span class="texhtml">δ</span><sup>13</sup>C<sub></sub>, with lower pCO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub> during glacial periods causing isotopic discrimination in plants using dissolved CO<sub style="font-size: 80%;vertical-align: -0.35em">2</sub>.</li> <li>Changes in Dominant Vegetation Within the Watershed: Shifts in watershed vegetation, especially transitions between C3 and C4 photosynthetic pathways, significantly alter the carbon isotopic composition in lake sediments. These changes can be indicative of broader paleoclimatic shifts.</li> <li>Diagenetic Trends: Diagenetic processes, such as the loss of reactive components like amino acids, result in sustained shifts in <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> in organic matter. Marsh sediments, rich in carbon, exhibit shifts towards more negative bulk organic matter. These diagenetic trends should be considered when interpreting isotopic changes accompanying major Total Organic Carbon (TOC) changes or methanogenesis.</li></ol> <p>Understanding these processes is crucial for interpreting <span class="texhtml">δ</span><sup>13</sup>C<sub></sub> variations in lake sediments and reconstructing paleoenvironmental conditions. </p> <div class="mw-heading mw-heading2"><h2 id="Major_excursion_events">Major excursion events</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=6" title="Edit section: Major excursion events"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Lomagundi-Jatuli_event" class="mw-redirect" title="Lomagundi-Jatuli event">Lomagundi-Jatuli event</a> (2,300–2,080 Ma) <a href="/wiki/Paleoproterozoic" title="Paleoproterozoic">Paleoproterozoic</a> - Positive excursion</li></ul> <ul><li><a href="/w/index.php?title=Shunga-Francevillian_event&action=edit&redlink=1" class="new" title="Shunga-Francevillian event (page does not exist)">Shunga-Francevillian event</a> (2,080 Ma) <a href="/wiki/Paleoproterozoic" title="Paleoproterozoic">Paleoproterozoic</a> - Negative excursion</li></ul> <ul><li><a href="/wiki/Shuram_excursion" title="Shuram excursion">Shuram-Wonoka excursion</a> (570–551 Ma) <a href="/wiki/Neoproterozoic" title="Neoproterozoic">Neoproterozoic</a> - Negative excursion</li></ul> <ul><li><a href="/wiki/Steptoean_positive_carbon_isotope_excursion" title="Steptoean positive carbon isotope excursion">Steptoean positive carbon isotope excursion</a> (494.6-492 Ma) <a href="/wiki/Paleozoic" title="Paleozoic">Paleozoic</a> - Positive excursion</li></ul> <ul><li><a href="/wiki/Ireviken_event" title="Ireviken event">Ireviken event</a> (433.4 Ma) <a href="/wiki/Paleozoic" title="Paleozoic">Paleozoic</a> - Positive excursion</li></ul> <ul><li><a href="/wiki/Mulde_event" title="Mulde event">Mulde event</a> (427 Ma) <a href="/wiki/Paleozoic" title="Paleozoic">Paleozoic</a> - Positive excursion</li></ul> <ul><li><a href="/wiki/Lau_event" title="Lau event">Lau event</a> (424 Ma) <a href="/wiki/Paleozoic" title="Paleozoic">Paleozoic</a> - Positive excursion</li></ul> <ul><li><a href="/wiki/Cenomanian-Turonian_boundary_event" title="Cenomanian-Turonian boundary event">Cenomanian-Turonian boundary event</a> (93.9 Ma) <a href="/wiki/Mesozoic" title="Mesozoic">Mesozoic</a> - Positive excursion</li></ul> <ul><li><a href="/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum" title="Paleocene–Eocene Thermal Maximum">Paleocene–Eocene Thermal Maximum</a> (55.5 Ma) <a href="/wiki/Cenozoic" title="Cenozoic">Cenozoic</a> - Negative excursion</li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=7" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/%CE%9418O" title="Δ18O"><span class="texhtml">δ</span><sup>18</sup>O</a></li> <li><a href="/wiki/%CE%9415N" title="Δ15N"><span class="texhtml">δ</span><sup>15</sup>N</a></li> <li><a href="/wiki/%CE%9434S" title="Δ34S"><span class="texhtml">δ</span><sup>34</sup>S</a></li> <li><a href="/wiki/Isotopic_signature" title="Isotopic signature">Isotopic signature</a></li> <li><a href="/wiki/Isotope_analysis" title="Isotope analysis">Isotope analysis</a></li> <li><a href="/wiki/Isotope_geochemistry" title="Isotope geochemistry">Isotope geochemistry</a></li> <li><a href="/wiki/Isotopic_labeling" title="Isotopic labeling">Isotopic labeling</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=%CE%9413C&action=edit&section=8" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFLibes1992" class="citation book cs1">Libes, Susan M. 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(2016-01-01). <a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fpac-2015-0503">"Isotopic compositions of the elements 2013 (IUPAC Technical Report)"</a>. <i>Pure and Applied Chemistry</i>. <b>88</b> (3): <span class="nowrap">293–</span>306. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1515%2Fpac-2015-0503">10.1515/pac-2015-0503</a></span>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/11858%2F00-001M-0000-0029-C408-7">11858/00-001M-0000-0029-C408-7</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1365-3075">1365-3075</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Pure+and+Applied+Chemistry&rft.atitle=Isotopic+compositions+of+the+elements+2013+%28IUPAC+Technical+Report%29&rft.volume=88&rft.issue=3&rft.pages=%3Cspan+class%3D%22nowrap%22%3E293-%3C%2Fspan%3E306&rft.date=2016-01-01&rft_id=info%3Ahdl%2F11858%2F00-001M-0000-0029-C408-7&rft.issn=1365-3075&rft_id=info%3Adoi%2F10.1515%2Fpac-2015-0503&rft.aulast=Meija&rft.aufirst=Juris&rft.au=Coplen%2C+Tyler+B.&rft.au=Berglund%2C+Michael&rft.au=Brand%2C+Willi+A.&rft.au=De+Bi%C3%A8vre%2C+Paul&rft.au=Gr%C3%B6ning%2C+Manfred&rft.au=Holden%2C+Norman+E.&rft.au=Irrgeher%2C+Johanna&rft.au=Loss%2C+Robert+D.&rft_id=https%3A%2F%2Fdoi.org%2F10.1515%252Fpac-2015-0503&rfr_id=info%3Asid%2Fen.wikipedia.org%3A%CE%9413C" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFMeier-Augenstein2017" class="citation book cs1">Meier-Augenstein, Wolfram (28 September 2017). <a rel="nofollow" class="external text" href="https://www.worldcat.org/oclc/975998493"><i>Stable isotope forensics : methods and forensic applications of stable isotope analysis</i></a> (Second ed.). Hoboken, NJ. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-119-08022-0" title="Special:BookSources/978-1-119-08022-0"><bdi>978-1-119-08022-0</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/975998493">975998493</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Stable+isotope+forensics+%3A+methods+and+forensic+applications+of+stable+isotope+analysis&rft.place=Hoboken%2C+NJ&rft.edition=Second&rft.date=2017-09-28&rft_id=info%3Aoclcnum%2F975998493&rft.isbn=978-1-119-08022-0&rft.aulast=Meier-Augenstein&rft.aufirst=Wolfram&rft_id=https%3A%2F%2Fwww.worldcat.org%2Foclc%2F975998493&rfr_id=info%3Asid%2Fen.wikipedia.org%3A%CE%9413C" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_book" title="Template:Cite book">cite book</a>}}</code>: CS1 maint: location missing publisher (<a href="/wiki/Category:CS1_maint:_location_missing_publisher" title="Category:CS1 maint: location missing publisher">link</a>)</span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFMichenerLajtha2007" class="citation book cs1">Michener, Robert; <a href="/wiki/Kate_Lajtha" title="Kate Lajtha">Lajtha, Kate</a>, eds. 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Miller (2012) [2003]. <i>Biological Oceanography</i> (2nd ed.). Oxford: John Wiley & Sons. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4443-3301-5" title="Special:BookSources/978-1-4443-3301-5"><bdi>978-1-4443-3301-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Biological+Oceanography&rft.place=Oxford&rft.edition=2nd&rft.pub=John+Wiley+%26+Sons&rft.date=2012&rft.isbn=978-1-4443-3301-5&rft.aulast=Miller&rft.aufirst=Charles+B.&rft.au=Patricia+A.+Miller&rfr_id=info%3Asid%2Fen.wikipedia.org%3A%CE%9413C" class="Z3988"></span></li> <li><a href="/wiki/Wim_Mook" title="Wim Mook">Mook, W. G.</a>, & Tan, F. C. (1991). Stable carbon isotopes in rivers and estuaries. Biogeochemistry of major world rivers, 42, 245–264.</li></ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Δ13C&oldid=1273754767">https://en.wikipedia.org/w/index.php?title=Δ13C&oldid=1273754767</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Bioindicators" title="Category:Bioindicators">Bioindicators</a></li><li><a href="/wiki/Category:Carbon" title="Category:Carbon">Carbon</a></li><li><a href="/wiki/Category:Isotopes_of_carbon" title="Category:Isotopes of carbon">Isotopes of carbon</a></li><li><a href="/wiki/Category:Environmental_isotopes" title="Category:Environmental isotopes">Environmental isotopes</a></li><li><a href="/wiki/Category:Geochemistry" title="Category:Geochemistry">Geochemistry</a></li><li><a href="/wiki/Category:Paleoclimatology" title="Category:Paleoclimatology">Paleoclimatology</a></li><li><a href="/wiki/Category:Isotope_excursions" title="Category:Isotope excursions">Isotope excursions</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:CS1_maint:_location_missing_publisher" title="Category:CS1 maint: location missing publisher">CS1 maint: location missing publisher</a></li><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_matches_Wikidata" title="Category:Short description matches Wikidata">Short description matches Wikidata</a></li><li><a href="/wiki/Category:All_articles_with_unsourced_statements" title="Category:All articles with unsourced statements">All articles with unsourced statements</a></li><li><a href="/wiki/Category:Articles_with_unsourced_statements_from_April_2019" title="Category:Articles with unsourced statements from April 2019">Articles with unsourced statements from April 2019</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 3 February 2025, at 21:38<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. 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mw-ui-icon-wikimedia-history mw-ui-icon-wikimedia-wikimedia-history"></span> <span></span> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only mw-watchlink" id="ca-watchstar-sticky-header" tabindex="-1" data-event-name="watch-sticky-header"><span class="vector-icon mw-ui-icon-wikimedia-star mw-ui-icon-wikimedia-wikimedia-star"></span> <span></span> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-edit-sticky-header" tabindex="-1" data-event-name="wikitext-edit-sticky-header"><span class="vector-icon mw-ui-icon-wikimedia-wikiText mw-ui-icon-wikimedia-wikimedia-wikiText"></span> <span></span> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-ve-edit-sticky-header" tabindex="-1" data-event-name="ve-edit-sticky-header"><span class="vector-icon mw-ui-icon-wikimedia-edit mw-ui-icon-wikimedia-wikimedia-edit"></span> <span></span> </a> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only" id="ca-viewsource-sticky-header" tabindex="-1" data-event-name="ve-edit-protected-sticky-header"><span class="vector-icon mw-ui-icon-wikimedia-editLock mw-ui-icon-wikimedia-wikimedia-editLock"></span> <span></span> </a> </div> <div class="vector-sticky-header-buttons"> <button class="cdx-button cdx-button--weight-quiet mw-interlanguage-selector" id="p-lang-btn-sticky-header" tabindex="-1" data-event-name="ui.dropdown-p-lang-btn-sticky-header"><span class="vector-icon mw-ui-icon-wikimedia-language mw-ui-icon-wikimedia-wikimedia-language"></span> <span>11 languages</span> </button> <a href="#" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive" id="ca-addsection-sticky-header" tabindex="-1" data-event-name="addsection-sticky-header"><span class="vector-icon mw-ui-icon-speechBubbleAdd-progressive mw-ui-icon-wikimedia-speechBubbleAdd-progressive"></span> <span>Add topic</span> </a> </div> <div class="vector-sticky-header-icon-end"> <div class="vector-user-links"> </div> </div> </div> </div> </div> <div class="mw-portlet mw-portlet-dock-bottom emptyPortlet" id="p-dock-bottom"> <ul> </ul> </div> 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