A Seasonal to Interannual View of Inorganic and Organic Carbon and pH in Western Lake Superior

Research output: Contribution to journalArticle

Abstract

To investigate the carbon cycle of Lake Superior, Earth's largest freshwater lake by surface area, we performed total organic carbon, dissolved organic carbon, chlorophyll, spectrophotometric pH, total inorganic carbon, and alkalinity measurements on seasonal samples from the western lake. The last three parameters, along with in situ temperature, were used to calculate the partial pressure of carbon dioxide in surface water (pCO2(w)) using the CO2SYS algorithm. There was a strong positive correlation between pH and water temperature and a weaker but significant positive correlation between pH and chlorophyll concentration. Total organic carbon exhibited higher nearshore concentrations (as determined by a negative correlation with total water column depth); such a spatial relationship did not appear in the inorganic carbon parameters (total inorganic carbon, pH, or pCO2(w)). Western Lake Superior exhibited net outgassing in spring, little net gas transfer in summer, and some outgassing in the fall. The pCO2(w) values were negatively correlated with both water temperature and chlorophyll concentration. Seasonal differences in pCO2(w) in Lake Superior appeared more strongly driven by biology and terrestrial inputs as compared to direct effects of temperature on CO2 solubility. Interannual data from the long-term Great Lakes Environmental Database data set indicated that lake alkalinity has been increasing over the past 20 years, and lake surface water pH appeared relatively stable. Modeling pH change over the same time frame in CO2SYS shows that increases in alkalinity and lake surface water temperature counteract the increase in atmospheric carbon dioxide concentration, leading to a relatively constant pH, consistent with observational data.

Original languageEnglish (US)
Pages (from-to)405-419
Number of pages15
JournalJournal of Geophysical Research: Biogeosciences
Volume124
Issue number2
DOIs
StatePublished - Feb 1 2019

Fingerprint

Lake Superior
inorganic carbon
Organic carbon
Lakes
organic carbon
lakes
carbon
alkalinity
lake
water temperature
chlorophylls
surface water
Chlorophyll
Carbon
chlorophyll
Alkalinity
Surface waters
outgassing
carbon dioxide
lake water

Keywords

  • Lake Superior
  • alkalinity
  • inorganic carbon
  • organic carbon
  • pCO2
  • pH

Cite this

A Seasonal to Interannual View of Inorganic and Organic Carbon and pH in Western Lake Superior. / Austin-Minor, Elizabeth C; Tennant, Cody James; Brown, Erik T.

In: Journal of Geophysical Research: Biogeosciences, Vol. 124, No. 2, 01.02.2019, p. 405-419.

Research output: Contribution to journalArticle

@article{b5ab50ba857f48959df3b3f2a96770d7,
title = "A Seasonal to Interannual View of Inorganic and Organic Carbon and pH in Western Lake Superior",
abstract = "To investigate the carbon cycle of Lake Superior, Earth's largest freshwater lake by surface area, we performed total organic carbon, dissolved organic carbon, chlorophyll, spectrophotometric pH, total inorganic carbon, and alkalinity measurements on seasonal samples from the western lake. The last three parameters, along with in situ temperature, were used to calculate the partial pressure of carbon dioxide in surface water (pCO2(w)) using the CO2SYS algorithm. There was a strong positive correlation between pH and water temperature and a weaker but significant positive correlation between pH and chlorophyll concentration. Total organic carbon exhibited higher nearshore concentrations (as determined by a negative correlation with total water column depth); such a spatial relationship did not appear in the inorganic carbon parameters (total inorganic carbon, pH, or pCO2(w)). Western Lake Superior exhibited net outgassing in spring, little net gas transfer in summer, and some outgassing in the fall. The pCO2(w) values were negatively correlated with both water temperature and chlorophyll concentration. Seasonal differences in pCO2(w) in Lake Superior appeared more strongly driven by biology and terrestrial inputs as compared to direct effects of temperature on CO2 solubility. Interannual data from the long-term Great Lakes Environmental Database data set indicated that lake alkalinity has been increasing over the past 20 years, and lake surface water pH appeared relatively stable. Modeling pH change over the same time frame in CO2SYS shows that increases in alkalinity and lake surface water temperature counteract the increase in atmospheric carbon dioxide concentration, leading to a relatively constant pH, consistent with observational data.",
keywords = "Lake Superior, alkalinity, inorganic carbon, organic carbon, pCO2, pH",
author = "Austin-Minor, {Elizabeth C} and Tennant, {Cody James} and Brown, {Erik T}",
year = "2019",
month = "2",
day = "1",
doi = "10.1029/2018JG004664",
language = "English (US)",
volume = "124",
pages = "405--419",
journal = "Journal of Geophysical Research D: Atmospheres",
issn = "0148-0227",
publisher = "American Geophysical Union",
number = "2",

}

TY - JOUR

T1 - A Seasonal to Interannual View of Inorganic and Organic Carbon and pH in Western Lake Superior

AU - Austin-Minor, Elizabeth C

AU - Tennant, Cody James

AU - Brown, Erik T

PY - 2019/2/1

Y1 - 2019/2/1

N2 - To investigate the carbon cycle of Lake Superior, Earth's largest freshwater lake by surface area, we performed total organic carbon, dissolved organic carbon, chlorophyll, spectrophotometric pH, total inorganic carbon, and alkalinity measurements on seasonal samples from the western lake. The last three parameters, along with in situ temperature, were used to calculate the partial pressure of carbon dioxide in surface water (pCO2(w)) using the CO2SYS algorithm. There was a strong positive correlation between pH and water temperature and a weaker but significant positive correlation between pH and chlorophyll concentration. Total organic carbon exhibited higher nearshore concentrations (as determined by a negative correlation with total water column depth); such a spatial relationship did not appear in the inorganic carbon parameters (total inorganic carbon, pH, or pCO2(w)). Western Lake Superior exhibited net outgassing in spring, little net gas transfer in summer, and some outgassing in the fall. The pCO2(w) values were negatively correlated with both water temperature and chlorophyll concentration. Seasonal differences in pCO2(w) in Lake Superior appeared more strongly driven by biology and terrestrial inputs as compared to direct effects of temperature on CO2 solubility. Interannual data from the long-term Great Lakes Environmental Database data set indicated that lake alkalinity has been increasing over the past 20 years, and lake surface water pH appeared relatively stable. Modeling pH change over the same time frame in CO2SYS shows that increases in alkalinity and lake surface water temperature counteract the increase in atmospheric carbon dioxide concentration, leading to a relatively constant pH, consistent with observational data.

AB - To investigate the carbon cycle of Lake Superior, Earth's largest freshwater lake by surface area, we performed total organic carbon, dissolved organic carbon, chlorophyll, spectrophotometric pH, total inorganic carbon, and alkalinity measurements on seasonal samples from the western lake. The last three parameters, along with in situ temperature, were used to calculate the partial pressure of carbon dioxide in surface water (pCO2(w)) using the CO2SYS algorithm. There was a strong positive correlation between pH and water temperature and a weaker but significant positive correlation between pH and chlorophyll concentration. Total organic carbon exhibited higher nearshore concentrations (as determined by a negative correlation with total water column depth); such a spatial relationship did not appear in the inorganic carbon parameters (total inorganic carbon, pH, or pCO2(w)). Western Lake Superior exhibited net outgassing in spring, little net gas transfer in summer, and some outgassing in the fall. The pCO2(w) values were negatively correlated with both water temperature and chlorophyll concentration. Seasonal differences in pCO2(w) in Lake Superior appeared more strongly driven by biology and terrestrial inputs as compared to direct effects of temperature on CO2 solubility. Interannual data from the long-term Great Lakes Environmental Database data set indicated that lake alkalinity has been increasing over the past 20 years, and lake surface water pH appeared relatively stable. Modeling pH change over the same time frame in CO2SYS shows that increases in alkalinity and lake surface water temperature counteract the increase in atmospheric carbon dioxide concentration, leading to a relatively constant pH, consistent with observational data.

KW - Lake Superior

KW - alkalinity

KW - inorganic carbon

KW - organic carbon

KW - pCO2

KW - pH

UR - http://www.scopus.com/inward/record.url?scp=85062356600&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85062356600&partnerID=8YFLogxK

U2 - 10.1029/2018JG004664

DO - 10.1029/2018JG004664

M3 - Article

VL - 124

SP - 405

EP - 419

JO - Journal of Geophysical Research D: Atmospheres

JF - Journal of Geophysical Research D: Atmospheres

SN - 0148-0227

IS - 2

ER -