Research Projects
- Tropical Climate &
Hydrology Since the Last Glacial Maximum
- Tropical Pacific climate changes during the last
2,000 years
- Holocene changes in the Intertropical Convergence
Zone (ITCZ)
- Paleohydrologic reconstructions from
molecular & isotopic changes in tropical Pacific
lake, bog & ocean sediments
- El Niño-Southern Oscillation variations since the
last
glacial maximum
- SST reconstructions from alkenones
in Eastern Equatorial Pacific sediments
- Leduc,
Sachs, Kawka, Schneider (in press). “Holocene changes in eastern
equatorial Atlantic salinity as estimated by water
isotopologues.” Earth and
Planetary Science Letters.
- Smittenberg, Saenger, Dawson, Sachs (2011) Compound-specific
D/H ratios of the marine lakes of Palau as proxies for West Pacific
Warm Pool hydrologic variability. Quaternary
Science Reviews Vol. 30: 921-933.
- Carré, Azzoug, Bentaleb, Chase, Fontugne, Jackson,
Ledru, Maldonado, Sachs, Schauer (2012) Mid-Holocene
mean climate in the south eastern Pacific and its influence on South
America. Quaternary International.
- Sachs & Myhrvold (2011) "A
shifting band of rain." Scientific
American Vol. 304: 60-65.
- Zhang, Metzger, Sachs (2011) "Co-occurrence
of long chain diols, keto-ols, hydroxy acids and keto acids in recent
sediments of Lake El Junco, Galapagos Islands." Organic Geochemistry Vol. 42:
823-837.
- Sachs & Ladd (2010) "Climate
and oceanography of the Galapagos in the 21st century: expected changes
and research needs." Galapagos
Research Vol. 67: 50-54.
- Sachs, Sachse, Smittenberg,
Zhang, Battisti, Golubic (2009) "Southward
movement of the Pacific intertropical convergence zone AD 1400-1850."
Nature
Geoscience, 2(7): 519-525.
- Koutavas
& Sachs (2008) Northern
timing of deglaciation in the
eastern equatorial Pacific from alkenone paleothermometry, Paleoceanography
Vol. 23: PA4205, doi:10.1029/2008PA001593.
- Sachse & Sachs (2008) Inverse
relationship between D/H fractionation in cyanobacterial lipids and
salinity in Christmas Island saline ponds. Geochimica et Cosmochimica Acta
Vol.72: 793-806.
- Pahnke,
Sachs, Keigwin, Timmermann, Xie
(2007) Eastern
tropical Pacific
hydrologic changes during the past 27,000 years from D/H ratios in
alkenones, Paleoceanography
Vol. 22, PA4214, doi:10.1029/2007PA001468.
- Smittenberg & Sachs (2007) Purification
of dinosterol for hydrogen isotopic analysis using high-performance
liquid chromatography–mass spectrometry Journal of Chromatography A
Vol. 1169: 70-76.
- Zhang, Metzger & Sachs
(2007) Biomarker
evidence for the co-occurrence of three races (A,
B and L) of Botryococcus braunii in El Junco Lake,
Galápagos, Organic
Geochemistry Vol. 38: 1459-1478.
- Saenger, Smittenberg, Miller, Sachs (2006) A
Physico-chemical survey of inland lakes and saline ponds: Christmas
Island (Kiritimati) and Washington (Teraina) Islands, Republic of
Kiribati Saline
Systems Vol. 2(1): 8
- Sachs
& Smittenberg (2005) Reconstructing the History of El
Niño from Galapagos Lakes EAPSpeaks,
MIT-EAPS Newsletter Vol. 1(1).
- Koutavas, Lynch-Stieglitz,
Marchitto, Sachs (2002) "El
Niño–like pattern in Ice Age tropical
Pacific sea surface temperature." Science
Vol. 297:
226-230.
- Hydrogen and
carbon isotopes in algal & plant lipids and their
application to paleoclimatology
- Phytoplankton Continuous cultures
We are growing mangroves in order to quantify the
hydrogen and carbon isotope fractionation during lipid synthesis across
a range of salinities. This research was motivated by graduate
student Nemiah Ladd's observation that hydrogen
isotope ratios in lipids from the leaves of the gray mangrove, Avicennia marina, decreased as
salinity increased
in the Brisbane River (SE Queensland, Australia). This is
opposite the fractionation response observed in phytoplankton, whose
lipids are characterized by an increase in their deuterium-to-hydrogen
ratio as salinity increases (see our studies from Christmas Island and the Chesapeake Bay).
We would like to quantify this response with controlled
experiments with a variety of mangrove species so that we can
calibrate a paleosalinity proxy from mangrove lipids in sediment
cores. These experiments are being
performed by graduate student Nemiah Ladd with assistance from UW
Biology undergraduate June Landenburger.
Our first mangroves were planted in our lab
in July, 2011 with propagules of Rhizophera
apiculata that we collected in Pohnpei, Micronesia. The figure on the left shows
the outside
of 3 of the growing tanks, covered with plastic to maintain high
humidity.
There is a mock tidal cycle with two high and two low tides per
day. The figure on the right
shows the inside of the 15 PSU salinity tank on
October 3, 2011. The largest plants are Rhizophera apiculata. There
are also Rhizophera mangle
and Laguncularia racemosa
plants growing in this tank, from propagules and seeds from
Florida. If you look closely you can also see some Xylocarpus granatum
seeds that have roots, but no shoots yet. These were collected in
Kosrae, Micronesia in September, 2011.
 
In order to expand the number of plants and salinities we
could maintain, and better control temperature and humidity, we moved
our mangrove experiments to the University of
Washington Botany Greenhouse in mid-2012. As of December,
2012 we have 6 species of mangroves growing at 6 different salinities
(see below images).
The large number of species are required in order to evaluate the
mechanisms responsible for hydrogen isotope fractionation in mangrove
lipids as a function of salinity since three different strategies for
managing salt are employed by mangroves, alone or in combination.
The images below are from October 11, 2012. Below left you can see tall shoots
of Heritiera littoralis (from
Honolulu, HI) and young Rhizophera apiculata (from
Pohnpei, FSM) plants. Below
right you can see shoots of Xylocarpus
granatum amongst young
Rhizophera apiculata plants,
both of which were collected in Pohnpei, Micronesia in August 2012.
- Field Studies: Yap,
Chuuk, Pohnpei & Guam (2012), Station ALOHA Cruise, R/V Thomas G. Thompson (2012), NE
Pacific Cruise, R/V Point Sur
(2012), Brisbane
River (2010), Saline
Lakes of Canada's Western Great Plains & Utah's Great Salt Lake
(2007), Cargill-Newark
Salt Works (2008), Christmas
Island (2005), Chesapeake
Bay (2006)
- Publications:
- Ladd & Sachs (2012) Inverse
relationship between salinity and n-alkane δD values in the mangrove Avicennia marina. Organic Geochemistry Vol. 48: 25-36.
- Atwood & Sachs (2012) Purification
of dinosterol from complex mixtures of sedimentary lipids for hydrogen
isotope analysis. Organic
Geochemistry Vol. 48: 37-46.
- Sachse et al. (2012). Molecular
paleohydrology: Interpreting the hydrogen-isotopic composition of lipid
biomarkers from photosynthesizing organisms. Annual Review of Earth and Planetary
Sciences, 40: 221-249
- Sachs & Schwab (2011) Hydrogen
isotopes in dinosterol from the Chesapeake Bay estuary. Geochimica et Cosmochimica Acta
Vol. 75(2): 444-459.
- Schwab & Sachs (2011) Hydrogen isotopes in
individual alkenones from the Chesapeake Bay estuary. Geochimica et Cosmochimica Acta,
75(23): 7552–7565.
- Schwab & Sachs (2009) The
measurement of D/H ratios in alkenones and their isotopic heterogeneity.
Organic
Geochemistry Vol. 40: 111-118.
- Zhang, Z., J.P. Sachs, A. Marchetti
(2009) Hydrogen
isotope fractionation in freshwater and marine algae: II. Temperature
and nitrogen-limited-growth-rate effects. Organic Geochemistry
Vol. 40(3): 428-439.
- Bühring, S.I., R.H. Smittenberg, D. Sachse, J.S.
Lipp, S. Golubic, J.P. Sachs, K.-U. Hinrichs, R.E. Summons (2009) "A
hypersaline microbial mat from the Pacific Atoll Kiritimati: insights
into composition and carbon fixation using biomarker analyses and a
13C-labeling approach." Geobiology
7: 1-16.
- Bowman
& Sachs (2008) Chemical
and physical properties of some saline lakes in Alberta and Saskatchewan,
Saline
Systems. Vol. 4:3.
- Sachse
& Sachs (2008) Inverse
relationship between D/H fractionation in cyanobacterial lipids and
salinity in Christmas Island saline ponds, Geochimica et Cosmochimica Acta
Vol.72: 793-806.
- Zhang & Sachs (2007) Hydrogen
isotope fractionation in freshwater algae: I. Variations
among lipids and species, Organic
Geochemistry
Vol. 38: 582-608.
- Smittenberg & Sachs (2007) Purification
of dinosterol for hydrogen isotopic analysis using high-performance
liquid chromatography-mass spectrometry. Journal of Chromatography A,
1169(1-2), 70-76.
- Englebrecht & Sachs (2005) Determination
of sediment provenance at drift sites using hydrogen isotopes and
unsaturation ratios in alkenones, Geochimica et Cosmochimica Acta
Vol. 69(17): 4253-4265
- El Niño & Peru Upwelling from Mollusks
JISAO Postdoctoral Fellow, Matthieu Carré
(now CNRS Chargés de Recherche at Univ. of Montpellier, France), is
using oxygen and carbon stable isotopes in mollusk shells from middens
along the coast of Peru to reconstruct the history of upwelling and El
Niño during the Holocene.
- Carré, Sachs, Schauer, Rodriguez (in press).
“Reconstructing El Niño-Southern Oscillation activity and ocean
temperature seasonality from short-lived marine mollusk shells from
Peru.” Palaeogeography,
Palaeoclimatology, Palaeoecology.
- Carré, Azzoug, Bentaleb, Chase, Fontugne, Jackson,
Ledru, Maldonado, Sachs, Schauer (2012) Mid-Holocene
mean climate in the south eastern Pacific and its influence on South
America. Quaternary International,
253: 55-66.
- Sadler, Carré, Azzoug, Schauer, Ledesma, Cardenas,
Chase, Bentaleb, Müller, Mandeng, Rohling, Sachs (2012). Reconstructing
past upwelling intensity and the seasonal dynamics of primary
productivity along the Peruvian coastline from mollusk shell stable
isotopes. Geochemistry,
Geophysics, Geosystems, 13(1): Q01015. doi:10.1029/2011GC003595.
- Carré, Sachs, Wallace, Favier (2012). Exploring
errors in paleoclimate proxy reconstructions using Monte Carlo
simulations: paleotemperature from mollusk and coral geochemistry. Climate of the Past, 8: 433-450.
- Deep ocean oxygen,
carbon storage & the
biological pump
- Carré, Azzoug, Bentaleb, Chase, Fontugne, Jackson,
Ledru, Maldonado, Sachs, Schauer (2011) Mid-Holocene
mean climate in the south eastern Pacific and its influence on South
America. Quaternary International
In Press, Corrected Proof.
- Koutavas
& Sachs (2008) Northern
timing of deglaciation in the
eastern equatorial Pacific from alkenone paleothermometry, Paleoceanography
Vol. 23: PA4205, doi:10.1029/2008PA001593.
- Pahnke
& Sachs (2006) "Sea
surface temperatures of southern
middle-latitudes 0-160 ky BP."
Paleoceanography
Vol. 21: PA2003, doi:10.1029/2005PA001191
- Sachs
& Anderson (2003) "Fidelity
of alkenone paleotemperature
reconstructions in southern Cape Basin sediment drifts" Paleoceanography
Vol. 18(4): 1082.
- Stenni
et al. (2003)
"A
late-glacial high resolution site and source temperature record
derived from the EPICA Dome C isotope records (East Antarctica)." Earth and Planetary Science
Letters Vol. 217: 183-195.
- Koutavas, Lynch-Stieglitz,
Marchitto, Sachs (2002) "El
Niño–like pattern in Ice Age tropical
Pacific sea surface temperature." Science
Vol. 297:
226-230.
- Lehman, Sachs, Crotwell, Keigwin, Boyle (2002). "Relation
of subtropical Atlantic temperature, high latitude ice rafting, deep
water formation, and European climate 135,000-60,000 years ago."
Quaternary Science Reviews 21: 1917-1924.
- Sachs,
Anderson & Lehman (2001) "Glacial
surface temperatures of the
southeast Atlantic Ocean." Science
Vol. 293:
2077-2079.
- Sachs & Lehman (1999) "Subtropical
North Atlantic temperatures 60,000 to 30,000 years ago." Science Vol. 286: 756-759.
- Holocene cooling of
the Northwest Atlantic Ocean
- The origin of fine
particles in sediment
drifts
-
- Eastern Mediterranean sapropels
- Nitrogen & carbon isotopes in chlorophyll
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People
Julian
Sachs -
Principal Investigator
 Dr. Josh Gregersen - Research Scientist/
Engineer 3 & Lab Manager
 Dan Nelson - Graduate Student
 Alyssa
Atwood - Graduate Student,
NSF Graduate Fellow, DOE Graduate Fellow
 Nemiah Ladd
- Graduate Student, NSF Graduate Fellow
 Ashley
Maloney - Graduate Student, UW Program on Climate Change Fellow, Global
Change IGERT Fellow
 Johnny Huynh - UW Oceanography Undergraduate, Mary
Gates Scholar
 Ariel Townsend - UW Oceanography
Undergraduate
 Chris Paschall - UW Oceanography
Undergraduate
 June Landenburger - UW Biology
Undergraduate
Ryan D'Jay - UW Oceanography Undergraduate
Lab Alumni
Kathleen Hemeon -
Research Aide I, Phytoplankton Specialist
 Dr. Julie Richey - NOAA Postdoctoral Fellow
 Dr.
Avery Cook Shinneman - Postdoctoral Investigator
 Dr. Ines
Mügler -
Humboldt Postdoctoral Fellow
 Dr.
Orest Kawka - Lab Manager / Research Scientist II
 Amanda Chomos, Laboratory
Assistant
 Dr. Juzhi Hou - UW PCC
Postdoctoral Fellow
 Dr. Matthieu
Carre - JISAO Postdoctoral Fellow
 Brittany Demianew - Research Scientist I
 Dr. Valerie Schwab - Swiss NSF Postdoctoral Fellow
 Dr.
Dirk
Sachse - Humboldt Postdoctoral Fellow
Dr.
Katharina
Pahnke - Comer Postdoctoral Fellow
Dr.
Zhaohui
Zhang - Comer Postdoctoral Fellow
Casey
Saenger - Graduate Student
Recent
Undergraduate Researchers
 Conor Myhrvold - Princeton
Undergrad., MIT Science
Writing Graduate Student
 Tory Johnson - UW Undergraduate
 Thien-Y, Le - UW Undergraduate
 Jake Zaragoza - JISAO Summer Intern /
Gonzaga Univ. Undergraduate
 Kyle Thomas - Texas Southern
University Undergraduate, NOAA/JISAO Intern
 Fran Janny - UW Undergraduate
 Jeff Bowman
- Levinson & Mary Gates Scholar
Jane Lee
Eric Battisti
Brittany Demianew
Carie Frantz
Evan Howard
Brittany Kimball
Daniel Luksic
Jen Nomura
Recent High
School Interns
 David Golub - Interlake
High School Gifted Student Intern
 Nathan Kato - Interlake High
School Gifted Student Intern
Lab Photos
(We like to snowboard & ski!)
 Mount Baker - March 25, 2012
L to R: Dan, Ashley, Julian, Josh
Crystal Mountain - March 29, 2011
L to R: Julian, Dan, Avery, Julie, Mat, Ashley
Ashley & Julie on SHENDA - Nov 2, 2010
 Crystal Mountain - March
15, 2010
L to R: Alyssa, Julian, Dan, Nemiah, Sarah, Jesse
 Crystal Mountain -
April 5, 2009
L to R: Julian, Dan, Mt. Rainier, Alyssa, Orest
 Mt. Baker Powder Day - March 31,
2008
L to R: Alyssa, Julian, Dan
 Mt. Baker Powder
Day - April 11, 2007
L to R: Orest, Rienk, Valerie, Matthieu, Julian, Dirk
 Steven's Pass Powder Day - March 9, 2006
L to R: Luzzi, Valerie, Julian, Dirk, Rienk
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Chesapeake
Bay: May 2006
Preparing a
Filtration System
Inside of batch culturing
chamber
Chemostat Culture of 
