Isoscape

An isoscape is a map of isotope distributions. It is a spatially explicit prediction of elemental isotope ratios (δ) that is produced by executing process-level models of elemental isotope fractionation or distribution in a geographic information system (GIS).

The word isoscape is derived from isotope landscape and was first coined by Jason B. West.[1][2]

Isoscapes of hydrogen, carbon, oxygen, nitrogen, strontium and sulfur[3] have been used to answer scientific or forensic questions regarding the sources, partitioning, or provenance of natural and synthetic materials or organisms via their isotopic signatures. These include questions about Earth's element cycles, human water use, climate, archaeological reconstructions, forensic science, pollution, organismal migration patterns and food web dynamics. Isoscapes of hydrogen and oxygen isotopes, modeling precipitation,[4][5] surface water,[6][7] groundwater,[8][9] and tap water[10] have been developed to better understand the water cycle at regional to global scales. Isoscapes of carbon and nitrogen isotopes have also been developed terrestrially and oceanographically[11][12] to help understand ecosystem dynamics.

Marine Isoscapes

Carbon Isoscapes[12][7]

Scientists are able to map carbon isotope ratios (δ13C) due to the predictable sorting of two stable isotopes of carbon: 13C and 12C. This sorting is known as isotope fractionation. In the ocean, δ13C changes due to many environmental factors including water temperature, upwelling of deep ocean water, diffusion of CO₂ from the air into the ocean and the burning of fossil fuels. Carbon fixation by primary producers also greatly influences δ13C at the oceans surface. Different groups of primary producers such as phytoplankton and macroalgae have different strategies for fixing carbon during photosynthesis and can further alter δ13C. As a result carbon isoscapes in the ocean largely reflect global patterns of temperature and primary production.

Since δ13C is influenced by so many factors, isoscapes are powerful for visualizing spatial or temporal patterns and provide baseline context for applications of stable isotope analysis in marine systems. Carbon isoscapes can be used in conjunction with stable isotope analysis of marine consumers or apex predators to determine the relative contributions of different primary producers to a food web or infer migration patterns of a consumer between isotopically distinct locations.

Nitrogen Isoscapes [11][7]

Like carbon, scientists are able to map nitrogen isotope ratios (δ15N) due to the fractionation of two stable isotopes of nitrogen: 14N and 15N. Marine nitrogen is sourced from diffusion of N₂ from the air into the ocean, freshwater run-off from continents including fertilizers and other land-based nutrients, and nitrogen fixation by primary producers like cyanobacteria which can all influence the baseline δ15N of the ocean in a given area. From there, nitrogen fractionation is mainly controlled through biological processes that utilize nitrogen, further detailed in the marine nitrogen cycle. For example the process of denitrification and the use of NH4+ (ammonia), NO2-, and NO3- (nitrate) by marine organisms alters the δ15N in the water. As a result, δ15N patterns in the ocean reflect areas where nitrogen is being heavily altered through denitrification or by organismal use within a food web. It is important to note that seasonality influencing primary productivity also plays a role in δ15N patterns at certain times of the year. For an example of marine nitrogen isoscape... [11].

Due to the large role of biological reactions on the fractionation of nitrogen, δ15N isoscapes provide valuable information for stable isotope analysis in marine ecology. Nitrogen isoscapes provide spatial and temporal δ15N baselines that can be used to inform food web studies. Due to the alteration of nitrogen as it is passed up the food chain, stable isotope analysis of marine consumers can be paired with δ15N isoscapes to place a consumer at a trophic level within a food web.

See also

Notes

  1. ^ "First appearance of "isoscapes" at a scientific meeting".
  2. ^ Bowen, Gabriel J.; West, Jason B.; Vaughn, Bruce H.; Dawson, Todd E.; Ehleringer, James R.; Fogel, Marilyn L.; Hobson, Keith; Hoogewerff, Jurian; Kendall, Carol; Lai, Chun-Ta; Miller, C. C.; Noone, David; Schwarcz, Henry; Still, Christopher J. (2009). "Isoscapes to Address Large-Scale Earth Science Challenges". Eos, Transactions, American Geophysical Union. 90 (13): 109–116. Bibcode:2009EOSTr..90..109B. doi:10.1029/2009EO130001.
  3. ^ Clément Bataille; Klervia Jaouen (2021). "Triple sulfur-oxygen-strontium isotopes probabilistic geographic assignment of archaeological remains using a novel sulfur isoscape of western Europe". PLOS One. 16 (5) e0250383. Bibcode:2021PLoSO..1650383B. doi:10.1371/journal.pone.0250383. PMC 8099095. PMID 33951062. Open access.
  4. ^ Dutton, Andrea; Wilkinson, Bruce H.; Welker, Jeffrey M.; Bowen, Gabriel J.; Lohmann, Kyger C. (2005-12-30). "Spatial distribution and seasonal variation in 18 O/ 16 O of modern precipitation and river water across the conterminous USA". Hydrological Processes. 19 (20): 4121–4146. Bibcode:2005HyPr...19.4121D. doi:10.1002/hyp.5876. hdl:2027.42/49284. S2CID 54706113.
  5. ^ Bowen, Gabriel J.; Wassenaar, Leonard I.; Hobson, Keith A. (April 2005). "Global application of stable hydrogen and oxygen isotopes to wildlife forensics". Oecologia. 143 (3): 337–348. Bibcode:2005Oecol.143..337B. doi:10.1007/s00442-004-1813-y. ISSN 0029-8549. PMID 15726429. S2CID 1762342.
  6. ^ Kendall, Carol; Coplen, Tyler B. (May 2001). "Distribution of oxygen-18 and deuterium in river waters across the United States". Hydrological Processes. 15 (7): 1363–1393. Bibcode:2001HyPr...15.1363K. doi:10.1002/hyp.217. ISSN 0885-6087. S2CID 27744095.
  7. ^ a b c "Ocean ecogeochemistry: a review", Oceanography and Marine Biology, CRC Press, pp. 335–398, 2013-08-28, ISBN 978-0-429-09951-9, retrieved 2025-10-09
  8. ^ Stahl, Mason O.; Gehring, Jaclyn; Jameel, Yusuf (2020-07-30). "Isotopic variation in groundwater across the conterminous United States – Insight into hydrologic processes". Hydrological Processes. 34 (16): 3506–3523. Bibcode:2020HyPr...34.3506S. doi:10.1002/hyp.13832. ISSN 0885-6087. S2CID 219743798.
  9. ^ Wassenaar, L. I.; Van Wilgenburg, S. L.; Larson, K.; Hobson, K. A. (2009-09-01). "A groundwater isoscape (δD, δ18O) for Mexico". Journal of Geochemical Exploration. 102 (3): 123–136. doi:10.1016/j.gexplo.2009.01.001. ISSN 0375-6742.
  10. ^ Bowen, Gabriel J.; Ehleringer, James R.; Chesson, Lesley A.; Stange, Erik; Cerling, Thure E. (March 2007). "Stable isotope ratios of tap water in the contiguous United States: STABLE ISOTOPE RATIOS OF TAP WATER". Water Resources Research. 43 (3). doi:10.1029/2006WR005186. S2CID 129888952.
  11. ^ a b c Somes, Christopher J.; Schmittner, Andreas; Galbraith, Eric D.; Lehmann, Moritz F.; Altabet, Mark A.; Montoya, Joseph P.; Letelier, Ricardo M.; Mix, Alan C.; Bourbonnais, Annie; Eby, Michael (2010). "Simulating the global distribution of nitrogen isotopes in the ocean". Global Biogeochemical Cycles. 24 (4). doi:10.1029/2009GB003767. ISSN 1944-9224.
  12. ^ a b Magozzi, S.; Yool, A.; Vander Zanden, H. B.; Wunder, M. B.; Trueman, C. N. (2017). "Using ocean models to predict spatial and temporal variation in marine carbon isotopes". Ecosphere. 8 (5): e01763. doi:10.1002/ecs2.1763. ISSN 2150-8925.
  13. ^ Magozzi, S.; Yool, A.; Vander Zanden, H. B.; Wunder, M. B.; Trueman, C. N. (2017). "Using ocean models to predict spatial and temporal variation in marine carbon isotopes". Ecosphere. 8 (5): e01763. doi:10.1002/ecs2.1763. ISSN 2150-8925.


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