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Monitoring of shallow groundwater in Lower Saxony, Germany—spatial variability of redox conditions and benefit of the redox proxy ∆Mn-Fe.

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Title: Monitoring of shallow groundwater in Lower Saxony, Germany—spatial variability of redox conditions and benefit of the redox proxy ∆Mn-Fe.
Authors: Hamer, K.1 (AUTHOR) khamer@uni-bremen.de, Ritter, J.1 (AUTHOR) johannes.ritter95@web.de
Source: Environmental Monitoring & Assessment. Oct2025, Vol. 197 Issue 10, p1-19. 19p.
Subject Terms: *Groundwater, *Trend analysis, *Water management, *Environmental monitoring, *Reduction potential, *Spatial variation
Geographic Terms: Lower Saxony (Germany), Germany
Abstract: Surveillance monitoring of shallow groundwater revealed that redox conditions can vary on a small scale. Therefore, the aim of this study was to categorize redox conditions in the groundwater of Lower Saxony, Germany, and to analyze the spatial distribution and trends of parameters related to redox conditions during surveillance monitoring from 1957 to 2015 in Lower Saxony, Germany. Methodically, trends were considered by applying the Mann-Kendall test and redox conditions of groundwater were classified according to the scheme of Jurgens et al. (2009). While the porous aquifers were dominated by anoxic redox conditions, the karst and joint aquifers presented a high percentage of the oxic redox category. A third of the monitoring wells showed trends with respect to redox conditions. Positive ΔMn-Fe values, indicating manganese-reducing conditions, were observed in 17% of the samples, which were mostly taken in areas of high groundwater recharge. Remarkably, different redox regimes were sampled in close neighborhoods within areas that were assumed to be homogeneous with respect to recharge rate, usage, and hydrogeology. In conclusion, parameters that are sensitive to redox conditions should be investigated stepwise; first, monitoring wells should be categorized according to the redox conditions and second, only wells with the same redox conditions should be compared. Third, the parameter ∆Mn-Fe should serve as a proxy for potential changes of the redoxcline, e.g., due to nitrate emissions to shallow groundwater. This stepwise procedure allows the assessment of groundwater and can serve as a basis for the design of measures to reach environmental aims according to the European Water Framework Directive. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
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  Availability: 0
Header DbId: enr
DbLabel: Energy & Power Source
An: 188714804
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Data: Monitoring of shallow groundwater in Lower Saxony, Germany—spatial variability of redox conditions and benefit of the redox proxy ∆<subscript>Mn-Fe</subscript>.
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  Data: <searchLink fieldCode="AR" term="%22Hamer%2C+K%2E%22">Hamer, K.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> khamer@uni-bremen.de</i><br /><searchLink fieldCode="AR" term="%22Ritter%2C+J%2E%22">Ritter, J.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> johannes.ritter95@web.de</i>
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  Data: <searchLink fieldCode="JN" term="%22Environmental+Monitoring+%26+Assessment%22">Environmental Monitoring & Assessment</searchLink>. Oct2025, Vol. 197 Issue 10, p1-19. 19p.
– Name: Subject
  Label: Subject Terms
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  Data: *<searchLink fieldCode="DE" term="%22Groundwater%22">Groundwater</searchLink><br />*<searchLink fieldCode="DE" term="%22Trend+analysis%22">Trend analysis</searchLink><br />*<searchLink fieldCode="DE" term="%22Water+management%22">Water management</searchLink><br />*<searchLink fieldCode="DE" term="%22Environmental+monitoring%22">Environmental monitoring</searchLink><br />*<searchLink fieldCode="DE" term="%22Reduction+potential%22">Reduction potential</searchLink><br />*<searchLink fieldCode="DE" term="%22Spatial+variation%22">Spatial variation</searchLink>
– Name: SubjectGeographic
  Label: Geographic Terms
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Lower+Saxony+%28Germany%29%22">Lower Saxony (Germany)</searchLink><br /><searchLink fieldCode="DE" term="%22Germany%22">Germany</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Surveillance monitoring of shallow groundwater revealed that redox conditions can vary on a small scale. Therefore, the aim of this study was to categorize redox conditions in the groundwater of Lower Saxony, Germany, and to analyze the spatial distribution and trends of parameters related to redox conditions during surveillance monitoring from 1957 to 2015 in Lower Saxony, Germany. Methodically, trends were considered by applying the Mann-Kendall test and redox conditions of groundwater were classified according to the scheme of Jurgens et al. (2009). While the porous aquifers were dominated by anoxic redox conditions, the karst and joint aquifers presented a high percentage of the oxic redox category. A third of the monitoring wells showed trends with respect to redox conditions. Positive ΔMn-Fe values, indicating manganese-reducing conditions, were observed in 17% of the samples, which were mostly taken in areas of high groundwater recharge. Remarkably, different redox regimes were sampled in close neighborhoods within areas that were assumed to be homogeneous with respect to recharge rate, usage, and hydrogeology. In conclusion, parameters that are sensitive to redox conditions should be investigated stepwise; first, monitoring wells should be categorized according to the redox conditions and second, only wells with the same redox conditions should be compared. Third, the parameter ∆Mn-Fe should serve as a proxy for potential changes of the redoxcline, e.g., due to nitrate emissions to shallow groundwater. This stepwise procedure allows the assessment of groundwater and can serve as a basis for the design of measures to reach environmental aims according to the European Water Framework Directive. [ABSTRACT FROM AUTHOR]
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=enr&AN=188714804
RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.1007/s10661-025-14557-7
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 19
        StartPage: 1
    Subjects:
      – SubjectFull: Groundwater
        Type: general
      – SubjectFull: Trend analysis
        Type: general
      – SubjectFull: Water management
        Type: general
      – SubjectFull: Environmental monitoring
        Type: general
      – SubjectFull: Reduction potential
        Type: general
      – SubjectFull: Spatial variation
        Type: general
      – SubjectFull: Lower Saxony (Germany)
        Type: general
      – SubjectFull: Germany
        Type: general
    Titles:
      – TitleFull: Monitoring of shallow groundwater in Lower Saxony, Germany—spatial variability of redox conditions and benefit of the redox proxy ∆Mn-Fe.
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            NameFull: Hamer, K.
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            NameFull: Ritter, J.
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            – D: 01
              M: 10
              Text: Oct2025
              Type: published
              Y: 2025
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              Value: 197
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              Value: 10
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            – TitleFull: Environmental Monitoring & Assessment
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