Fe and Nutrients in Coastal Antarctic Streams

95 Pages·2017·3.68 MB·English

Fe
 and
 Nutrients
 in
 Coastal
 Antarctic
 Streams:
 Implications
 for
 Marine
 Primary

Production
 in
 the
 Ross
 Sea

THESIS

Presented
 in
 Partial
 Fulfillment
 of
 the
 Requirements
 for
 the
 Degree
 Master
 of
 Science
 in

the
 Graduate
 School
 of
 the
 Ohio
 State
 University

By

Sydney
 A.
 Olund,
 B.S.

Graduate
 Program
 in
 Earth
 Sciences

The
 Ohio
 State
 University

2017

Thesis
 Committee:

Dr.
 W.
 Berry
 Lyons,
 Advisor

Dr.
 Yu-­‐Ping
 Chin

Dr.
 Michael
 Durand
Copyright
 by

Sydney
 Olund

2017
ABSTRACT

The
 Southern
 Ocean
 (SO)
 has
 been
 an
 area
 of
 much
 biogeochemical
 interest
 due

to
 the
 role
 of
 Fe
 limitation
 for
 primary
 production.
 Primary
 production
 is
 associated
 with

increased
 carbon
 sequestration,
 making
 it
 important
 to
 characterize
 and
 quantify
 the

fluxes
 of
 Fe
 and
 other
 nutrients
 to
 the
 ocean.
 Water
 samples
 were
 collected
 in
 the

McMurdo
 Dry
 Valleys,
 Antarctica
 (MDV)
 from
 four
 subaerial
 streams
 flowing
 into
 the

Ross
 Sea.
 They
 were
 analyzed
 for
 macronutrients
 (N,
 P,
 Si)
 and
 Fe
 to
 determine
 the

potential
 impact
 of
 terrestrial
 water
 input
 on
 the
 biogeochemistry
 of
 coastal
 oceanic

waters.
 Our
 stream
 data
 yield
 an
 average
 filterable
 composition
 of
 N3P1
 Si100Fe0.8,

which
 is
 substantially
 different
 from
 the
 planktonic
 composition
 as
 demonstrated
 by

empirical
 measurements,
 and
 suggests
 that
 these
 streams
 are
 a
 potential
 source
 of
 Fe

and
 P,
 relative
 to
 N
 and
 Si,
 to
 coastal
 phytoplankton
 communities.

The
 behavior
 and
 potential
 colloidal/nanoparticulate
 speciation
 of
 the
 Fe
 in

these
 streams
 was
 investigated
 through
 analysis
 of
 three
 physiochemical
 forms
 of
 Fe
 -­‐

environmentally
 active
 Fe
 (acid-­‐soluble/no
 filtration),
 filterable
 Fe
 (filtered
 through
 0.4

µm),
 and
 dissolved
 Fe
 (filtered
 through
 0.2
 µm).
 It
 has
 been
 suggested
 that
 the
 dissolved

ii
fraction
 is
 mainly
 nanoparticulate
 and
 represents
 a
 more
 bioavailable
 form
 of
 Fe,
 as

compared
 with
 colloids
 and
 particles.
 Overall,
 the
 combined
 average
 annual
 flux
 from

two
 MDV
 streams
 is
 approximately
 240
 moles
 fFe
 yr-­‐1,
 which
 is
 consistent
 with

previously
 predicted
 values.
 The
 dissolved
 fraction
 of
 Fe
 (<0.2
 µm)
 was
 between
 18%

and
 27%
 percent
 of
 the
 fFe,
 meaning
 the
 fFe
 pool
 is
 mostly
 colloidal.
 While
 the
 Fe
 flux

from
 these
 streams
 is
 several
 orders
 of
 magnitude
 less
 than
 aeolian
 and
 iceberg
 sources,

terrestrial
 streams
 are
 expected
 to
 become
 a
 more
 significant
 source
 of
 Fe
 to
 the
 Ross

Sea.
 As
 the
 Antarctic
 climate
 warms,
 ice-­‐free
 regions
 similar
 to
 the
 MDV
 should
 increase

in
 extent
 and
 glacier
 melt.
 This
 study
 questions
 how,
 and
 in
 what
 quantities,
 Fe
 is

solubilized
 and
 transported
 from
 the
 landscape
 into
 the
 SO
 to
 better
 inform
 predictions

of
 Fe
 fluxes
 following
 continued
 warming

ii i
ACKNOWLEDGEMENTS

First
 and
 foremost,
 I
 would
 like
 to
 thank
 Dr.
 Berry
 Lyons
 for
 providing
 the

opportunity
 to
 experience
 the
 wonders
 of
 Antarctic
 fieldwork,
 the
 encouragement
 to

“do
 good
 things”,
 and
 the
 guidance
 I
 needed
 to
 succeed
 in
 my
 graduate
 career.
 I
 will
 be

forever
 grateful
 for
 the
 experiences
 you
 provided
 me
 during
 these
 past
 two
 years.
 I’d
 like

to
 give
 a
 huge
 thanks
 to
 Elsa
 Saelens
 for
 assisting
 with
 fieldwork
 and
 being
 my
 Antarctic

confidant
 throughout
 our
 adventures
 on
 the
 ice
 and
 in
 the
 lab.
 Thank
 you
 to
 the
 2015-­‐
16
 LTER
 field
 crew
 for
 introducing
 me
 to
 “the
 dude”
 and
 providing
 fieldwork
 assistance,

conversation,
 laughs,
 and
 advice.
 A
 special
 thanks
 to
 Adam
 Wlostowski,
 for
 letting
 me

tag
 along
 on
 an
 impromptu
 helicopter
 tour
 of
 the
 Dry
 Valleys
 and
 for
 being
 a
 model
 of

scientific
 enthusiasm
 that
 encouraged
 me
 to
 keep
 questioning
 and
 learning
 throughout

the
 past
 year
 and
 a
 half.
 Thank
 you
 to
 Chris
 Jaros
 and
 Christa
 Torrens
 for
 answering
 my

many
 flow-­‐related
 questions,
 and
 specifically
 for
 the
 use
 of
 Chris’s
 flow
 model
 outputs.

Thank
 you
 to
 the
 Trace
 Element
 Research
 Lab,
 especially
 Anthony
 Lutton,
 for
 help
 and

support
 with
 my
 Fe
 analyses.
 Thanks
 to
 Kathy
 Welch
 for
 teaching
 me
 everything
 from

how
 to
 use
 a
 pipette
 to
 how
 to
 communicate
 science
 effectively.
 Your
 assistance
 with
 lab

work,
 field
 work,
 presentations
 of
 data,
 and
 life
 have
 been
 invaluable
 to
 me.
 Thanks
 to

Sue
 Welch
 for
 your
 help
 with
 nutrient
 analyses,
 SEM
 analyses,
 and
 feedback
 on

iv
presentations.
 Thanks
 to
 Chris
 Gardner
 for
 your
 straightforward
 and
 extremely
 helpful

review
 on
 multiple
 posters
 and
 talks.
 Thank
 you
 to
 Melisa
 Diaz
 for
 being
 a
 great
 friend,

office
 mate
 and
 science
 coach.
 Thank
 you
 to
 my
 committee
 for
 providing
 feedback
 on

this
 research.
 Thank
 you
 to
 NSF
 ANT
 1115245
 for
 funding
 support,
 to
 ASC
 for
 logistical

support,
 and
 to
 PHI
 for
 helicopter
 support.
 Lastly,
 thank
 you
 to
 my
 family
 for
 your
 love

and
 support.
 You
 mean
 the
 world
 to
 me.

v
VITA

April
 25,
 1992…………………………………………….
 Born
 –
 Evanston,
 Illinois

May
 2014……………………………………………………
 B.S.
 Geology
 and
 Earth
 Systems,

  Environment,
 and
 Society,
 University
 of

  Illinois
 at
 Urbana-­‐Champaign

August
 2015
 to
 present………………………………
 Graduate
 Research
 and
 Teaching
 Associate,

  School
 of
 Earth
 Sciences,
 The
 Ohio
 State

  University

Fields
 of
 Study

Major
 Field:
 Earth
 Sciences

v i
TABLE
 OF
 CONTENTS

ABSTRACT……………..….……………..………………....…………………….…………………………………………ii

ACKNOWLEDGEMENTS.……….………………………………….….…………………………………………….....iv

VITA……………………………………..………………………….………………….………………………………………...vi

LIST
 OF
 TABLES………………………..….………………………….…..….……………….…………………..……….ix

LIST
 OF
 FIGURES…….………………………..….………..….…………………..…………………….…………..…...xi

1
 INTRODUCTION..………………………..………………..….………………………………………………….………1

1.1
 Rationale
 for
 work..….…….……..….………………………..….……………………………….…..1

2
 STUDY
 AREA..
 ……………………….………..….………………………..……………..………………………..……6

2.1
 Site
 Description….…………………………………………………………...….………………………..6

3
 METHODS……....……….………………..….………………….…..….………………………….………..…………11

3.1
 Cleaning.
 ………………………..….………..…..……………….…………..….….………….……….11

3.2
 Sampling….……………………….……………..……………………………...….……………………..11

3.3
 Processing…...………………..….………………………..….…………….…………….……………..12

3.4
 Analysis………………..…….………………………..….………………….……………………….......12

4
 RESULTS…..….…………….……………..….………………………..….………………………………….………….15

vi i
4.1
 Fe
 and
 nutrients
 along
 stream
 transects
 and
 partial
 diels…………..….….……….15

4.2
 Hysteretic
 behavior
 in
 Commonwealth….………………………..………………..……..…18

4.3
 Nutrient
 Stoichiometry……………….….…..………..….…………………….………...…..…..20

4.4
 Physiochemical
 forms
 of
 Fe.
 ………………………..….…….……………………………….….21

4.5
 Fe
 flux.
 ………………………..….…………….……………………..…....….……………….………...22

5
 DISCUSSION….…..….………………………..….…………………….……………..….………………………..….23

5.1
 Fe
 and
 nutrient
 ratios
 in
 terrestrial
 stream
 and
 the
 Southern
 Ocean…....…….23

5.2
 Comparison
 to
 previously
 studied
 fluxes……….………………………..………………….25

5.3
 Potential
 impacts
 of
 climate
 change
 on
 streamflow
 in
 the
 MDVs.…...............26

5.4
 Fate
 of
 Fe
 in
 the
 Southern
 Ocean…..………….………………………………………………..27

6
 CONCLUSIONS……………………………………………………………………………………………………………29

6.1
 Summary
 of
 research……………………….…………....…….………………………………….…29

6.2
 Future
 work……………………………………………………………….………….…………………...29

7
 REFERENCES
 CITED…………………….……………………………………………………….…………………….31

APPENDIX
 A:
 TABLES
 AND
 FIGURES…………………………..………………………….………………………39

APPENDIX
 B:
 MAJOR
 CATIONS
 AND
 MAJOR
 ANIONS.……….………………………….…….………..73

APPENDIX
 C:
 TITRATION
 ALKALINITY
 AND
 pH……………..………………………………………………..80

vi ii
LIST
 OF
 TABLES

Table
 1.
 Precision
 and
 accuracy
 of
 major
 ion
 and
 nutrient
 data….…………………………………40

Table
 2.
 Precision
 and
 accuracy
 for
 three
 Fe
 analyses
 using
 inductively
 coupled

plasma………………………………………………………………………………………………………………………….41

Table
 3.
 Previously
 calculated
 Fe
 fluxes
 from
 various
 sources
 to
 the
 Southern

Ocean…………………………………………..…………………………………………………………….…………...…..42

Table
 4.
 Stream
 characteristics
 of
 coastal
 MDV
 streams………………..............………………….43

Table
 5.
 Annual
 discharge
 for
 the
 Commonwealth,
 Wales,
 Garwood,
 and
 Miers

Streams……………………………………………………………………………………………………….……………....44

Table
 6.
 Average
 Fe
 concentrations
 in
 four
 coastal
 MDV
 streams……………..…..……………..46

Table
 7.
 Average
 Fe
 flux
 from
 Commonwealth
 and
 Wales…..…………..….………………………..47

Table
 8.
 Ratios
 of
 average
 molar
 concentrations
 of
 filterable
 (<
 0.4
 µm)
 nutrients
 N,
 P,
 Si,

and
 Fe
 for
 3
 streams………………………..……..….………………………..….………………………..…………48

Table
 9.
 Major
 cation
 concentrations
 for
 all
 samples
 collected……………………………………..74

Table
 10.
 Major
 anion
 concentrations
 for
 all
 samples
 collected……………………………………77

ix