Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake
Abstract Arsenic (As), a harmful contaminant present in many urban lakes, can negatively impact lake ecosystem health when aqueous concentrations are elevated. We observed repeated diel oscillations in As concentrations in the bottom waters of a shallow, temperate lake during a weeklong period. In t...
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| Format: | Article |
| Language: | English |
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Wiley
2024-03-01
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| Series: | Water Resources Research |
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| Online Access: | https://doi.org/10.1029/2023WR035842 |
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| author | Samantha R. Fung Erin A. Hull James E. Gawel Alexander R. Horner‐Devine Rebecca B. Neumann |
| author_facet | Samantha R. Fung Erin A. Hull James E. Gawel Alexander R. Horner‐Devine Rebecca B. Neumann |
| author_sort | Samantha R. Fung |
| collection | DOAJ |
| description | Abstract Arsenic (As), a harmful contaminant present in many urban lakes, can negatively impact lake ecosystem health when aqueous concentrations are elevated. We observed repeated diel oscillations in As concentrations in the bottom waters of a shallow, temperate lake during a weeklong period. In this work, we explore four mechanistic hypotheses to explain the diel As cycles based on the physical and biogeochemical processes that were investigated during the study. Despite pH being known to control diel As cycles in rivers, we determined that this mechanism was inconsistent with As dynamics observed in Lake Killarney. Instead, we found that iron and manganese concentrations oscillated simultaneously with As concentrations and that redox conditions adjacent to the lakebed likely controlled the near‐bed availability of these three elements. However, based on timescale analysis, we determined that biogeochemical processes at the sediment water interface alone could not have led to the daily oscillations in bottom water concentrations. Rather, turbulence from convective mixing was necessary to transport dissolved species. Notably, we saw that the timing and intensity of peaks in convectively driven turbulence were consistent with observed diel fluctuations in bottom water As. Our results indicate that physical mixing is key in controlling As transport and concentrations on diel timescales within shallow lakes. Understanding the daily cycling of As in shallow lakes is essential for predicting the degree to which lake biota are exposed to this contaminant. Diel oscillations in As concentrations should be considered when designing sampling methods to assess the water quality of contaminated sites. |
| format | Article |
| id | doaj-art-7be2984ec2574dcfbd925a291d58d8d6 |
| institution | OA Journals |
| issn | 0043-1397 1944-7973 |
| language | English |
| publishDate | 2024-03-01 |
| publisher | Wiley |
| record_format | Article |
| series | Water Resources Research |
| spelling | doaj-art-7be2984ec2574dcfbd925a291d58d8d62025-08-20T02:36:42ZengWileyWater Resources Research0043-13971944-79732024-03-01603n/an/a10.1029/2023WR035842Short‐Term Arsenic Cycling in a Shallow, Polymictic LakeSamantha R. Fung0Erin A. Hull1James E. Gawel2Alexander R. Horner‐Devine3Rebecca B. Neumann4Department of Civil and Environmental Engineering University of Washington Seattle WA USASciences and Mathematics Division School of Interdisciplinary Arts and Sciences University of Washington Tacoma Tacoma WA USASciences and Mathematics Division School of Interdisciplinary Arts and Sciences University of Washington Tacoma Tacoma WA USADepartment of Civil and Environmental Engineering University of Washington Seattle WA USADepartment of Civil and Environmental Engineering University of Washington Seattle WA USAAbstract Arsenic (As), a harmful contaminant present in many urban lakes, can negatively impact lake ecosystem health when aqueous concentrations are elevated. We observed repeated diel oscillations in As concentrations in the bottom waters of a shallow, temperate lake during a weeklong period. In this work, we explore four mechanistic hypotheses to explain the diel As cycles based on the physical and biogeochemical processes that were investigated during the study. Despite pH being known to control diel As cycles in rivers, we determined that this mechanism was inconsistent with As dynamics observed in Lake Killarney. Instead, we found that iron and manganese concentrations oscillated simultaneously with As concentrations and that redox conditions adjacent to the lakebed likely controlled the near‐bed availability of these three elements. However, based on timescale analysis, we determined that biogeochemical processes at the sediment water interface alone could not have led to the daily oscillations in bottom water concentrations. Rather, turbulence from convective mixing was necessary to transport dissolved species. Notably, we saw that the timing and intensity of peaks in convectively driven turbulence were consistent with observed diel fluctuations in bottom water As. Our results indicate that physical mixing is key in controlling As transport and concentrations on diel timescales within shallow lakes. Understanding the daily cycling of As in shallow lakes is essential for predicting the degree to which lake biota are exposed to this contaminant. Diel oscillations in As concentrations should be considered when designing sampling methods to assess the water quality of contaminated sites.https://doi.org/10.1029/2023WR035842urban lakeshallow lake biogeochemistryshallow lake mixinglegacy arsenic contaminationdiel cyclingconvective mixing |
| spellingShingle | Samantha R. Fung Erin A. Hull James E. Gawel Alexander R. Horner‐Devine Rebecca B. Neumann Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake Water Resources Research urban lake shallow lake biogeochemistry shallow lake mixing legacy arsenic contamination diel cycling convective mixing |
| title | Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake |
| title_full | Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake |
| title_fullStr | Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake |
| title_full_unstemmed | Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake |
| title_short | Short‐Term Arsenic Cycling in a Shallow, Polymictic Lake |
| title_sort | short term arsenic cycling in a shallow polymictic lake |
| topic | urban lake shallow lake biogeochemistry shallow lake mixing legacy arsenic contamination diel cycling convective mixing |
| url | https://doi.org/10.1029/2023WR035842 |
| work_keys_str_mv | AT samantharfung shorttermarseniccyclinginashallowpolymicticlake AT erinahull shorttermarseniccyclinginashallowpolymicticlake AT jamesegawel shorttermarseniccyclinginashallowpolymicticlake AT alexanderrhornerdevine shorttermarseniccyclinginashallowpolymicticlake AT rebeccabneumann shorttermarseniccyclinginashallowpolymicticlake |