Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater?
The fluxes of water and solutes in the subsurface compartment of the Critical Zone are temporally dynamic and it is unclear how this impacts microbial mediated nutrient cycling in the spatially heterogeneous subsurface. To investigate this, we undertook numerical modeling, simulating the transport i...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-03-01
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| Series: | Frontiers in Water |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/frwa.2022.780297/full |
| _version_ | 1818774667379343360 |
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| author | Swamini Khurana Falk Heße Falk Heße Anke Hildebrandt Anke Hildebrandt Anke Hildebrandt Martin Thullner |
| author_facet | Swamini Khurana Falk Heße Falk Heße Anke Hildebrandt Anke Hildebrandt Anke Hildebrandt Martin Thullner |
| author_sort | Swamini Khurana |
| collection | DOAJ |
| description | The fluxes of water and solutes in the subsurface compartment of the Critical Zone are temporally dynamic and it is unclear how this impacts microbial mediated nutrient cycling in the spatially heterogeneous subsurface. To investigate this, we undertook numerical modeling, simulating the transport in a wide range of spatially heterogeneous domains, and the biogeochemical transformation of organic carbon and nitrogen compounds using a complex microbial community with four (4) distinct functional groups, in water saturated subsurface compartments. We performed a comprehensive uncertainty analysis accounting for varying residence times and spatial heterogeneity. While the aggregated removal of chemical species in the domains over the entire simulation period was approximately the same as that in steady state conditions, the sub-scale temporal variation of microbial biomass and chemical discharge from a domain depended strongly on the interplay of spatial heterogeneity and temporal dynamics of the forcing. We showed that the travel time and the Damköhler number (Da) can be used to predict the temporally varying chemical discharge from a spatially heterogeneous domain. In homogeneous domains, chemical discharge in temporally dynamic conditions could be double of that in the steady state conditions while microbial biomass varied up to 75% of that in steady state conditions. In heterogeneous domains, the interquartile range of uncertainty in chemical discharge in reaction dominated systems (log10Da > 0) was double of that in steady state conditions. However, high heterogeneous domains resulted in outliers where chemical discharge could be as high as 10–20 times of that in steady state conditions in high flow periods. And in transport dominated systems (log10Da < 0), the chemical discharge could be half of that in steady state conditions in unusually low flow conditions. In conclusion, ignoring spatio-temporal heterogeneities in a numerical modeling approach may exacerbate inaccurate estimation of nutrient export and microbial biomass. The results are relevant to long-term field monitoring studies, and for homogeneous soil column-scale experiments investigating the role of temporal dynamics on microbial redox dynamics. |
| first_indexed | 2024-12-18T10:44:47Z |
| format | Article |
| id | doaj.art-65cb0d65f8fd4bc383c37bcc742a96f8 |
| institution | Directory Open Access Journal |
| issn | 2624-9375 |
| language | English |
| last_indexed | 2024-12-18T10:44:47Z |
| publishDate | 2022-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Water |
| spelling | doaj.art-65cb0d65f8fd4bc383c37bcc742a96f82022-12-21T21:10:33ZengFrontiers Media S.A.Frontiers in Water2624-93752022-03-01410.3389/frwa.2022.780297780297Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater?Swamini Khurana0Falk Heße1Falk Heße2Anke Hildebrandt3Anke Hildebrandt4Anke Hildebrandt5Martin Thullner6Geomicrobial Reactive Transport Systems Group, Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, GermanyInstitute of Earth and Environmental Sciences-Geoecology, University Potsdam, Potsdam, GermanyDepartment of Computational Hydrosystems, Helmholtz Centre for Environmental Research—UFZ, Leipzig, GermanyDepartment of Computational Hydrosystems, Helmholtz Centre for Environmental Research—UFZ, Leipzig, GermanyInstitute of Geoscience, Friedrich-Schiller-University Jena, Jena, GermanyGerman Centre for Integrative Biodiversity Research, Leipzig, GermanyGeomicrobial Reactive Transport Systems Group, Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, GermanyThe fluxes of water and solutes in the subsurface compartment of the Critical Zone are temporally dynamic and it is unclear how this impacts microbial mediated nutrient cycling in the spatially heterogeneous subsurface. To investigate this, we undertook numerical modeling, simulating the transport in a wide range of spatially heterogeneous domains, and the biogeochemical transformation of organic carbon and nitrogen compounds using a complex microbial community with four (4) distinct functional groups, in water saturated subsurface compartments. We performed a comprehensive uncertainty analysis accounting for varying residence times and spatial heterogeneity. While the aggregated removal of chemical species in the domains over the entire simulation period was approximately the same as that in steady state conditions, the sub-scale temporal variation of microbial biomass and chemical discharge from a domain depended strongly on the interplay of spatial heterogeneity and temporal dynamics of the forcing. We showed that the travel time and the Damköhler number (Da) can be used to predict the temporally varying chemical discharge from a spatially heterogeneous domain. In homogeneous domains, chemical discharge in temporally dynamic conditions could be double of that in the steady state conditions while microbial biomass varied up to 75% of that in steady state conditions. In heterogeneous domains, the interquartile range of uncertainty in chemical discharge in reaction dominated systems (log10Da > 0) was double of that in steady state conditions. However, high heterogeneous domains resulted in outliers where chemical discharge could be as high as 10–20 times of that in steady state conditions in high flow periods. And in transport dominated systems (log10Da < 0), the chemical discharge could be half of that in steady state conditions in unusually low flow conditions. In conclusion, ignoring spatio-temporal heterogeneities in a numerical modeling approach may exacerbate inaccurate estimation of nutrient export and microbial biomass. The results are relevant to long-term field monitoring studies, and for homogeneous soil column-scale experiments investigating the role of temporal dynamics on microbial redox dynamics.https://www.frontiersin.org/articles/10.3389/frwa.2022.780297/fullreactive transport modelingspatio-temporal heterogeneityuncertaintygeomicrobial activitynutrient export |
| spellingShingle | Swamini Khurana Falk Heße Falk Heße Anke Hildebrandt Anke Hildebrandt Anke Hildebrandt Martin Thullner Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? Frontiers in Water reactive transport modeling spatio-temporal heterogeneity uncertainty geomicrobial activity nutrient export |
| title | Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? |
| title_full | Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? |
| title_fullStr | Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? |
| title_full_unstemmed | Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? |
| title_short | Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater? |
| title_sort | should we worry about surficial dynamics when assessing nutrient cycling in the groundwater |
| topic | reactive transport modeling spatio-temporal heterogeneity uncertainty geomicrobial activity nutrient export |
| url | https://www.frontiersin.org/articles/10.3389/frwa.2022.780297/full |
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