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Stratification of reactivity determines nitrate removal in groundwater

Title data

Kolbe, Tamara ; de Dreuzy, Jean-Raynald ; Abbott, Benjamin W. ; Aquilina, L. ; Babey, T. ; Green, C. ; Fleckenstein, Jan ; Labasque, T. ; Laverman, A.M. ; Marçais, Jean ; Peiffer, Stefan ; Thomas, Zahra ; Pinay, G.:
Stratification of reactivity determines nitrate removal in groundwater.
In: Proceedings of the National Academy of Sciences of the United States of America. Vol. 116 (12 February 2019) Issue 7 .
ISSN 1091-6490
DOI: https://doi.org/10.1073/pnas.1816892116

Abstract in another language

Biogeochemical reactions occur unevenly in space and time, but this heterogeneity is often simplified as a linear average due to sparse data, especially in subsurface environments where access is limited. For example, little is known about the spatial variability of groundwater denitrification, an important process in removing nitrate originating from agriculture and land use conversion. Information about the rate, arrangement, and extent of denitrification is needed to determine sustainable limits of human activity and to predict recovery time frames. Here, we developed and validated a method for inferring the spatialorganization of sequential biogeochemical reactions in an aquifer in France. We applied it to five other aquifers in different geological settings located in the United States and compared results among 44 locations across the six aquifers to assess the generality of reactivity trends. Of the sampling locations, 79% showed pronounced increases of reactivity with depth. This suggests that previous estimates of denitrification have underestimated the capacity of deep aquifers to remove nitrate, while overestimating nitrate removal in shallow flow paths. Oxygen and nitrate reduction likely increases with depth because there is relatively little organic carbon in agricultural soils and because excess nitrate input has depleted solid phase electron donors near the surface. Our findings explain the long-standing conundrum of why apparent reaction rates of oxygen in aquifers are typically smaller than those of nitrate, which is energetically less favorable. This stratified reactivity framework is promising for mapping vertical reactivity trends in aquifers, generating new understanding of subsurface ecosystems and their capacity to remove contaminants.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER149589
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Hydrology
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Hydrology > Chair Hydrology - Univ.-Prof. Dr. Stefan Peiffer
Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 25 Mar 2019 13:01
Last Modified: 25 Mar 2019 13:01
URI: https://eref.uni-bayreuth.de/id/eprint/48082