https://elementalcycles.org/about daily 0.75 2025-09-03 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/f4bef6fb-dde5-4863-9af5-d3eb5ab5a6b1/IMG_8548.jpeg about https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604268623541-0HA82EUD1N7RX6NET7NX/TethysDeer.jpeg about https://elementalcycles.org/publications daily 0.75 2026-03-13 https://elementalcycles.org/service daily 0.75 2025-05-01 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604255307838-9IAV5MTXH7UKGRVW5ZVG/SchoolLecture.jpg service Giving a lecture on isotope biogeochemistry in Blair High School’s biology class. Depending on the classroom and curriculum, topics include taphonomy and the history of life, glacial-interglacial cycles, isotope ratios in natural materials, the age of the Earth, what college is like, and my day-to-day life as a professional researcher. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604255542853-PC5V4M84OHB3110JPAUT/BoothCPASTEM2.jpg service Making comets out of dry ice, dirt (organic molecules!) and water during the Caltech “Science for March” event. Another demo at our booth was blowing into a cup of water with a pH meter to demonstrate ocean acidification, and adding carbonate to the cup to demonstrate buffering. https://elementalcycles.org/home daily 1.0 2022-09-09 https://elementalcycles.org/researchoverview daily 0.75 2022-08-21 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604185437886-4LOUPD6TFVAJRL783OXG/IMG_0476.JPG research overview https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604362728766-ERMYR9FJ1UGAOCX11FXV/IceBoat.jpg research overview https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/169829f1-8c44-446d-be46-da873d37f29c/ALKDICschematic_website.png research overview https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604185775968-QMZYGV7KKA7AKVN1CTVL/FocusQuad_1.jpg research overview https://elementalcycles.org/river-geochemistry daily 0.75 2024-03-14 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604197060829-O1ODV7AU7Y1DPC7NV295/103_DJI_0342.JPG river geochemistry The upper valley and headwaters of the Efri Haukadalsá catchment in Western Iceland. Our sampling transect ranges from the snowpack visible in the top-right to Haukadalsvatn, a lake at the end of the river. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604251657704-S4UDN4Y7HIYR9ISLJPFL/Piper_cut.png river geochemistry Calcium, magnesium, and sodium+potassium ternary diagram for samples from the Langtang-Trisuli-Narayani River system (large points) and samples published previously (smaller gray triangles). https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604196399983-Q0V4X6CDT7GGISM085DG/Alaska_Koy.png river geochemistry Elevation map of the Koyukuk River, hosted in discontinuous permafrost near Huslia, AK, with indicated sampling locations. https://elementalcycles.org/global-carbon-cycle daily 0.75 2024-03-14 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/9314d683-ffd7-4846-bedf-625cb2dfa101/Matrix1_v11_website.png carbon cycle - Make it stand out Matrix representation of biogeochemical reactions (Ax=b). Columns of the matrix A correspond to individual reactions and rows correspond to chemical species. Entries in A reflect stoichiometric coefficients (moles/reaction), entries in x describe reaction rates (reaction/time), and entries of b are time derivatives of chemical reservoirs (moles/time). https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604416676476-CAKXDYBPM5A7J5VTMA4D/MEANDIRlogo.png carbon cycle https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1631578402624-TU4S6XLGTFQXHWT2RPLK/RZC_Mackenzie4.png carbon cycle Results from MEANDIR inversion of river observations from the Mackenzie River (Horan et al., 2019). R is the fraction of carbonate weathering, Z is the fraction of weathering with sulfuric acid, and C tracks organic carbon oxidation relative to silicate and carbonate weathering. Color is the median ALK/DIC of inversion results. All samples have ALK/DIC ratios less than 2, implying that weathering upstream of the sampling site is associated with long-term increases in the atmospheric concentration of carbon dioxide. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/122d1a1c-736f-4f4d-bf2d-d0be6c494fe5/ALKDICschematic_website.png carbon cycle Some of the inputs and outputs to ocean-atmosphere dissolved inorganic carbon and alkalinity. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/8db25652-e5c9-4069-9d0e-4afbe90071b0/ALKDICcross.png carbon cycle - Make it stand out Geochemical processes alter the concentration of atmospheric carbon dioxide by altering ocean-atmosphere dissolved inorganic carbon and alkalinity. Note that, near modern conditions, contours of pCO2 have slopes approximately equal to 1. https://elementalcycles.org/ice-ages daily 0.75 2020-11-03 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604252300193-UMF0Y27GDDJ4TR2VJSIN/NO2d15Nwitherror.png ice ages Calculated nitrogen isotope ratios of nitrite in the Southern Ocean surface. These low values were interpreted as indicating exchange of N between nitrate and nitrite catalyzed by the nitrite oxidoreductase enzyme of organisms excavated into the surface ocean during seasonal mixed layer deepening. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604250347806-387SCUL351IRI1K9W5F9/ModelSchematicAZ201101.png ice ages The architecture of the seasonal model. Nitrate and ammonium are supplied to the photic zone and cycled among biological reservoirs, with isotopic fractionation, and sink into a synthetic sediment core. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604199571659-E4369EVGQ4CYSMLL3480/DSCN1663.jpg ice ages Yuzhen Yan standing outside the drill tent after a 5-day storm during the 2015-2016 field season. Note that the top of the drill has punctured the tent. Drilling continued after removing the snow and bending back a few poles. https://elementalcycles.org/other-interesting-ideas daily 0.75 2024-03-14 https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604252463814-R9IV8390IL5RVHGTMLRE/Backend_3.jpg other ideas Inside the detector housing of the Neptune plus, with visible Faraday cups and heating elements, from the perspective of looking through the exit of the flight tube. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604272409271-TE8FFMAL6039LL8RC611/LoadCoil2.jpg other ideas Changing the load coil of our Neptune Plus. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604254003290-QRMG8CZTN2386206MGG7/UBM.png other ideas A simplified version of the calculations of Urey, Bigeleisen, and Mayer, for determining isotopic distributions at thermodynamic equilibrium. Is there a set of fractionating processes dominated by pressure, or other thermodynamic variables, that can form the basis of new proxies? https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604363087793-ET6JOJA9SK0EVIA3KLYI/Seawater.jpg other ideas A float in the Southern Ocean. The interpretation of isotopic records is currently hindered by having few constraints on the concentration of marine elements through time. https://images.squarespace-cdn.com/content/v1/5f9db500e529e27a47041ea5/1604426694147-C6Z534QK9NK9GKKHG682/IsotopicTable.png other ideas Nuclide mass, coded by log-10 natural abundance. Orange boxes indicate nuclides with odd numbers of neutrons. Several monoisotopic systems are polyisotonic. The most abundant isotope of each element is indicated.