Groundwater travel times predict DOC in streams and riparian soils across a heterogeneous boreal landscape

The Science of The Total Environment, Год журнала: 2022, Номер 849, С. 157398 - 157398

Опубликована: Июль 21, 2022

Dissolved organic carbon (DOC) in surface waters is an important component of the boreal landscape budget and a critical variable water quality. A dominant terrestrial DOC source riparian zone. These near stream areas play key role regulating transport between land aquatic ecosystems. The groundwater dynamics at this interface have been considered major controlling for export to streams. This study focuses on levels mean travel times (MTT) concentrations and, subsequently, DOC. done by comparing them as explanatory variables capture spatial intra-annual variability We used physically based 3D hydrological model, Mike SHE, simulate zones 14 sub-catchments within Krycklan catchment (Sweden). model concept assumes that will be higher moving through shallow flow paths. In can linked position table point observation or time, which generally shorter has travelled more conductive soil layers. compared results with both observed concentrations. analysis revealed correlation modelled annual averages increased from r = 0.08 0.87 using MTT instead level. also better captured successfully represented seasonal We, therefore, suggest predictor than level concentration because it greater variety heterogeneities, such variation properties, size, input deep sources.

Язык: Английский

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Bridging the gap from hydrological to biogeochemical processes using tracer-aided hydrological models in a tropical montane ecosystem

Journal of Hydrology, Год журнала: 2023, Номер 619, С. 129328 - 129328

Опубликована: Март 3, 2023

Язык: Английский

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Stable water isotopes and tritium tracers tell the same tale: no evidence for underestimation of catchment transit times inferred by stable isotopes in StorAge Selection (SAS)-function models

Hydrology and earth system sciences, Год журнала: 2023, Номер 27(16), С. 3083 - 3114

Опубликована: Авг. 24, 2023

Abstract. Stable isotopes (δ18O) and tritium (3H) are frequently used as tracers in environmental sciences to estimate age distributions of water. However, it has previously been argued that seasonally variable tracers, such δ18O, generally systematically fail detect the tails water therefore substantially underestimate ages compared radioactive 3H. In this study for Neckar River basin central Europe based on a >20-year record hydrological, δ18O 3H data, we scrutinized above postulate together with potential role spatial aggregation effects exacerbating underestimation ages. This was done by comparing inferred from total 21 different model implementations, including time-invariant, lumped-parameter sine-wave (SW) convolution integral (CO) models well StorAge Selection (SAS)-function (P-SAS) integrated hydrological combination SAS functions (IM-SAS). We found that, indeed, commonly SW CO mean transit times (MTTs) ∼ 1–2 years lower than those obtained same models, reaching MTTs ∼10 years. contrast, several implementations P-SAS IM-SAS not only allowed simultaneous representations storage variations streamflow stream signals, but these were, 11–17 years, also much higher similar 3H, which suggested 11–13 Characterized parameter posterior distributions, particular parameters control age, individually constrained or observations exhibited limited differences magnitudes parts temporal variability time (TTDs) response changing wetness conditions. suggests both lead comparable descriptions how is routed through system. These findings provide evidence us reject hypothesis tracer “cannot see older about 4 years” truncates corresponding leading underestimations Instead, our results broad equivalence systems characterized at least 15–20 The question degree heterogeneity can further adversely affect estimates remains unresolved lumped distributed provided inconclusive results. Overall, demonstrates reported most likely result use other per se. Rather, largely be attributed choices approaches complexity considering transient conditions next aspects. Given additional vulnerability due potentially still unknown effects, advocate avoiding type if possible instead adopting SAS-based time-variant formulations models.

Язык: Английский

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Net landscape carbon balance of a tropical savanna: Relative importance of fire and aquatic export in offsetting terrestrial production

Global Change Biology, Год журнала: 2020, Номер 26(10), С. 5899 - 5913

Опубликована: Июль 20, 2020

Abstract The magnitude of the terrestrial carbon (C) sink may be overestimated globally due to difficulty accounting for all C losses across heterogeneous landscapes. More complete assessments net landscape balances (NLCB) are needed that integrate both emissions by fire and transfer aquatic systems, two key loss pathways C. These can particularly significant in wet–dry tropics, where plays a fundamental part ecosystems intense rainfall seasonal flooding result considerable export (ΣF aq ). Here, we determined NLCB lowland catchment (~140 km 2 ) tropical Australia over years evaluating productivity (NEP), fire‐related ΣF (comprising downstream transport gaseous evasion) main components, is, savanna woodland wetlands. We found was large (NLCB 334 Mg −2 year −1 ), wetland areas contributed 84% 16% this sink, respectively. Annually, (−56 (−28 reduced NEP 13% 7%, Savanna burning shifted source several months during dry season, while significantly offset wet with disproportionate contribution single major monsoonal events—up 39% annual exported one event. hypothesize wetter hotter conditions tropics future will increase emissions, potentially further reducing current region. long‐term studies upscale first estimate less productive, yet hydrologically dynamic regions our indicating not hold.

Язык: Английский

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Tracing Water Sources and Fluxes in a Dynamic Tropical Environment: From Observations to Modeling

Frontiers in Earth Science, Год журнала: 2020, Номер 8

Опубликована: Ноя. 6, 2020

Tropical regions cover approximately 36% of the Earth's landmass. These are home to 40% world's population, which is projected increase over 50% by 2030 under a remarkable climate variability scenario often exacerbated El Niño Southern Oscillation (ENSO) and other teleconnections. In tropics, ecohydrological conditions typically influence complex land-ocean-atmosphere interactions that produce dynamic cycling mass energy reflected in clear partition water fluxes. Here, we present review seven years concerted continuous stable isotope monitoring across Costa Rica, including key insights learned, main methodological advances limitations (both experimental designs data analysis), potential gaps, future research opportunities with humid tropical perspective. The uniqueness geographic location Rica within mountainous Central America Isthmus, receiving moisture inputs from Caribbean Sea (windward) Pacific Ocean (complex leeward topography), experiencing strong ENSO events, poses advantage for use isotopic variations underpin drivers responses. sequential approach, analyzed transport, rainfall generation, groundwater/surface connectivity Bayesian rainfall-runoff modeling. overarching goal this provide robust example progressive escalation common observations more modeling outputs applications enhance resource management tropics.

Язык: Английский

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Gross primary productivity and water use efficiency are increasing in a high rainfall tropical savanna

Global Change Biology, Год журнала: 2021, Номер 28(7), С. 2360 - 2380

Опубликована: Дек. 2, 2021

Despite their size and contribution to the global carbon cycle, we have limited understanding of tropical savannas current trajectory with climate change anthropogenic pressures. Here examined interannual variability externally forced long-term changes in water exchange from a high rainfall savanna site seasonal tropics north Australia. We used an 18-year flux data time series (2001-2019) detect trends drivers fluxes water. Significant positive gross primary productivity (GPP, 15.4 g C m2 year-2 ), ecosystem respiration (Reco , 8.0 net (NEE, 7.4 ) use efficiency (WUE, 0.0077 kg H2 O-1 year-1 were computed. There was weaker, non-significant trend latent energy (LE, 0.34 W m-2 ). Rainfall nearby increased statistically over 45-year period during observation period. To examine dominant GPP WUE, random forest approach terrestrial biosphere model conduct attribution experiment. Radiant driver wet season fluxes, whereas soil content dominated dry fluxes. The suggested that [CO2 ], precipitation Tair accounting for 90% modelled WUE. Positive largest implying tree components larger contributor than grassy understorey. Fluxes environmental not significant season, when grasses are active. is potentially still recovering cyclone 45 years ago regrowth this event may also be contributing observed sequestration, highlighting need understand sub-diurnal decadal scales.

Язык: Английский

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Nitrate isotopes in catchment hydrology: Insights, ideas and implications for models

Journal of Hydrology, Год журнала: 2023, Номер 626, С. 130326 - 130326

Опубликована: Окт. 20, 2023

Язык: Английский

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Recent Developments and Emerging Challenges in Tracer‐Aided Modeling

Wiley Interdisciplinary Reviews Water, Год журнала: 2025, Номер 12(2)

Опубликована: Март 1, 2025

ABSTRACT During the last decade, tracer‐aided hydrological models (TAMs) have been applied in numerous studies and successfully evolved for different purposes. Such confirmed value of tracer data modeling, offering insights into internal storages, water sources, flow pathways, mixing processes, ages, which cannot be derived from hydrometric alone. The direct coupling tracers flux tracking balance can reduce model uncertainty through increased biogeochemical process knowledge. More specifically, such simultaneously capture celerity responses with velocities (and age) particles. As a result availability high‐resolution characterizing functioning across Critical Zone entire landscapes, together rapid improvement computing capacity, four major advances reshaped capability TAMs, we review this paper: (1) enhanced representation spatial heterogeneity, (2) more explicit conceptualization ecohydrological partitioning, (3) application to larger catchment scales, (4) incorporation non‐conservative coupled quality modeling. However, persistent challenges also emerged, particularly relation acquisition, mismatches between information content scale application, uncertainties structures, as well adaptation multi‐criteria calibration. In review, recent remaining TAMs summarized discussed particular focus on conservative models.

Язык: Английский

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Stream respiration exceeds CO₂ evasion in a low‐energy, oligotrophic tropical stream

Limnology and Oceanography, Год журнала: 2023, Номер 68(5), С. 1132 - 1146

Опубликована: Март 12, 2023

Abstract Carbon dioxide (CO 2 ) can be either imported to streams through groundwater and subsurface inputs of soil‐respired CO or produced internally stream metabolism. The contribution each source the evasion flux from is not well quantified, especially in tropics, an underrepresented region carbon (C) cycling studies. We used high‐frequency measurements dissolved O concentrations estimate potential metabolism a tropical lowland headwater stream. found that was heterotrophic all year round, with net ecosystem productivity (NEP) values ranging 0.84 4.06 g C m −2 d −1 (median 1.29 ; here we expressed gross primary (GPP) as negative respiration (ER) positive flux). Positive NEP were result relatively low stable GPP seasons, compared higher more variable ER favored by high temperatures organic matter availability, particularly during wet season. due turbulence (median: 1.09 ). As result, daily rates exceeded 129% (median; 120–175% interquartile range), despite strong seasonal changes flow regime landscape connectivity. excess likely transported downstream, where it ultimately emitted atmosphere. Our results highlight overwhelming importance cycle low‐energy, oligotrophic streams.

Язык: Английский

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Revealing the positive influence of young water fractions derived from stable isotopes on the robustness of karst water resources predictions

Journal of Hydrology, Год журнала: 2023, Номер 621, С. 129549 - 129549

Опубликована: Апрель 23, 2023

Язык: Английский

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