Using stable isotopes as tracers of water masses and nutrient cycling processes in the Gulf of Maine

Whitney, Nina M.; Wanamaker, Alan D.; Switzer, Megan E.; Pettigrew, Neal R.

doi:10.1016/j.csr.2020.104210

Cited by 6 publications

(9 citation statements)

References 58 publications

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“…During the mid to late 1800s, the region experienced a rapid shift in hydrographic properties resulting in relatively high δ 18 O (indicative of colder or more saline waters), high δ 15 N (potentially indicative of the increased presence of LSW), and low Δ 14 C (again potentially indicative of the increased presence of LSW) 17 waters. This hydrographic composition peaks in the 1870s, as shown by segmented regression analysis on the δ 18 O record (which produces a breakpoint of 1875). From the 1870s until present day, waters in the region have gradually shifted towards a composition with larger contributions from waters with low δ 18 O, low δ 15 N, and higher Δ 14 C (this latter record only contains data up until 1935 due to atomic bombing testing in the 1950s), suggesting increasing WSW in the region.…”

Section: Resultsmentioning

confidence: 88%

“…Two separate proxy records of water mass variability (δ 18 O and δ 15 N) 27 are reconstructed (Fig. 2) from shells collected in the western Gulf of Maine (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…To assess the utility of using δ 18 O as a sea surface temperature proxy in the Gulf of Maine, we compared this record to various Gulf of Maine instrumental temperature records and gridded data products. Table 1 shows the maximum Pearson correlation coefficients, after accounting for autocorrelation, between the δ 18 O record presented in this study and an instrumental dataset (the BBH SST record 30 ) as well as various gridded data products (Extended Reconstructed Sea Surface Temperature -ERSST -v5 31 , Hadley Center Sea Ice and Sea Surface Temperature -HadISST-v1.1 32,33 , Optimum Interpolation Sea Surface Temperature -OISST-v2.1 34,35 , EN4.2.1 data product 36,37 for surface and 35 m) for the time period of overlap between all datasets . Supplementary Table 1 shows the Pearson correlation coefficients for the full range of overlap between the oxygen isotope record and each individual data product.…”

Section: Resultsmentioning

confidence: 99%

“…The reconstructed water properties in this study are derived from chemical proxies from A. islandica shells (Supplementary Fig. 1): oxygen isotopes (δ 18 O) as a proxy for seawater hydrography (temperature and salinity) and nitrogen isotopes (δ 15 N) as a proxy for water mass source. Additionally, these water properties are compared to a previously published record of age-corrected radiocarbon (Δ 14 C) 17 measured in the same A. islandica shells as those measured for δ 18 O and δ 15 N 18 .…”

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confidence: 99%

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Rapid 20th century warming reverses 900-year cooling in the Gulf of Maine

Whitney

Wanamaker

Ummenhofer

et al. 2022

Commun Earth Environ

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The Gulf of Maine, located in the western North Atlantic, has undergone recent, rapid ocean warming but the lack of long-term, instrumental records hampers the ability to put these significant hydrographic changes into context. Here we present multiple 300-year long geochemical records (oxygen, nitrogen, and previously published radiocarbon isotopes) measured in absolutely-dated Arctica islandica shells from the western Gulf of Maine. These records, in combination with climate model simulations, suggest that the Gulf of Maine underwent a long-term cooling over most of the last 1000 years, driven primarily by volcanic forcing and North Atlantic ocean dynamics. This cooling trend was reversed by warming beginning in the late 1800s, likely due to increased atmospheric greenhouse gas concentrations and changes in western North Atlantic circulation. The climate model simulations suggest that the warming over the last century was more rapid than almost any other 100-year period in the last 1000 years in the region.

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Section: Resultsmentioning

confidence: 88%

“…Two separate proxy records of water mass variability (δ 18 O and δ 15 N) 27 are reconstructed (Fig. 2) from shells collected in the western Gulf of Maine (Fig.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Rapid 20th century warming reverses 900-year cooling in the Gulf of Maine

Whitney

Wanamaker

Ummenhofer

et al. 2022

Commun Earth Environ

Self Cite

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show abstract

“…2). De este modo, las variaciones pueden reflejar diferencias en la entrada de agua dulce y de mezcla vertical (Whitney et al 2020). En las Figuras 1 y 3, se observa que las muestras más empobrecidas se presentaron en la parte norte del área de los CHPS, especialmente en las muestras superficiales (Fig.…”

Section: Resultados Y Discusiónunclassified

Primeras mediciones de isótopos estables de agua y su comportamiento en fiordos de los Campos de Hielo Patagónico Sur, Chile

Rodrigo

López

Cifuentes

et al. 2022

Rev. biol. mar. oceanogr.

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Stable isotope measurements of seawater from fjords in the Southern Patagonian Icefields area are presented for the first time. Stable water isotope variability was associated with physiographic and oceanographic factors. Isotope depletion and lower salinity were observed at lower depths, which is consistent with shallow estuarine waters. At greater depths, the characteristics of the modified Subantarctic water mass are inferred, and the glacier proximity and temperature do not show a clear relationship with the isotopic contents. These results could be a robust basis for a possible new proxy associated with changes in water masses, freshwater mixing, and paleoclimatic studies.

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Contrasting nitrogen dynamics across the Mid‐Atlantic Bight shelfbreak front: Insights from nitrate dual isotopes and nitrifier gene abundance

Zhu,

Mulholland,

Selden

et al. 2024

Limnology & Oceanography

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Observations and model studies suggest that front dynamics can enhance phytoplankton productivity. This study tested whether frontal systems also increase the abundance of nitrifying microbes and nitrogen recycling during repeat sampling transects across the Mid‐Atlantic Bight shelfbreak in July 2019. We measured ammonium concentrations, nitrate dual isotopes (δ15N, δ18O), and ammonia monooxygenase subunit A (amoA) genes of ammonia‐oxidizing archaea (AOA) and bacteria (AOB). In subsurface shelf waters, ammonium concentrations exceeded 2 μmol L−1, due to a temporary imbalance in regeneration from sinking particles and subsequent nitrification. The inverse correlation between nitrate δ15N values and ammonium concentrations confirmed nitrate was partially or entirely from local nitrification on the shelf. In contrast, the shelfbreak frontal zone and slope sea subsurface waters had much lower ammonium concentrations (0.1–0.2 μmol L−1) due to tight coupling between ammonium regeneration and nitrification. The deviation of nitrate δ15N and δ18O from algal uptake‐driven 1 : 1 ratio suggests concurrent nitrification in the euphotic zone. The shelfbreak front acted as an ecological boundary where AOA and AOB amoA gene numbers were partitioned, with AOAs abounding in slope waters and AOBs in shelf waters, likely due to ammonium availability. At certain slope stations, deep‐water nutrient inputs via isopycnal lifting induced by Gulf Stream intrusions caused unexpectedly high phytoplankton biomass, which doubled nitrifier abundance and potentially stimulated both ammonium regeneration and nitrification. These findings demonstrate distinct distributions of nitrifying microbes along the salinity gradient from shelf to slope and highlight the significant influence of coastal ocean‐western boundary current interactions on nitrogen biogeochemistry.

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Using stable isotopes as tracers of water masses and nutrient cycling processes in the Gulf of Maine

Cited by 6 publications

References 58 publications

Rapid 20th century warming reverses 900-year cooling in the Gulf of Maine

Rapid 20th century warming reverses 900-year cooling in the Gulf of Maine

Primeras mediciones de isótopos estables de agua y su comportamiento en fiordos de los Campos de Hielo Patagónico Sur, Chile

Contrasting nitrogen dynamics across the Mid‐Atlantic Bight shelfbreak front: Insights from nitrate dual isotopes and nitrifier gene abundance

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