Classification of hydrological regimes of northern floodplain basins (Peace–Athabasca Delta, Canada) from analysis of stable isotopes (δ¹⁸O, δ²H) and water chemistry

Abstract

Abstract:We used stable isotopes (υ 18 O and υ 2 H) and water chemistry to characterize the water balance and hydrolimnological relationships of 57 shallow aquatic basins in the Peace-Athabasca Delta (PAD), northern Alberta, Canada, based on sampling at the end of the 2000 thaw season. Evaporation-to-inflow ratios (E/I) were estimated using an isotope mass-balance model tailored to accommodate basin-specific input water compositions, which provided an effective, first-order, quantitative framework for identifying water balances and associated limnological characteristics spanning three main, previously identified drainage types. Open-drainage basins (E/I < 0Ð4; n D 5), characterized by low alkalinity, low concentrations of nitrogen, dissolved organic carbon (DOC) and ions, and high minerogenic turbidity, include large, shallow basins that dominate the interior of the PAD and experience frequent or continuous river channel connection. Closed-drainage basins (E/I ½ 1Ð0; n D 16), in contrast, possess high alkalinity and high concentrations of nitrogen, DOC, and ions, and low minerogenic turbidity, and are located primarily in the relict and infrequently flooded landscape of the northern Peace sector of the delta. Several basins fall into the restricted-drainage category (0Ð4 # E/I < 1Ð0; n D 26) with intermediate water chemistries and are predominant in the southern Athabasca sector, which is subject to active fluviodeltaic processes, including intermittent flooding from riverbank overflow. Integration of isotopic and limnological data also revealed evidence for a new fourth drainage type, mainly located near the large open-drainage lakes that occupy the central portion of the delta but within the Athabasca sector (n D 10). These basins were very shallow (<50 cm deep) at the time of sampling and isotopically depleted, corresponding to E/I characteristic of restricted-and open-drainage conditions. However, they are limnologically similar to closed-drainage basins except for higher conductivity and higher concentrations of Ca 2C and Na C , and lower concentrations of SiO 2 and chlorophyll c. These distinct features are due to the overriding influence of recent summer rainfall on the basin water balance and chemistry. The close relationships evident between water balances and limnological conditions suggest that past and future changes in hydrology are likely to be coupled with marked alterations in water chemistry and, hence, the ecology of aquatic environments in the PAD.

Spatial and temporal variability of prairie lake hydrology as revealed using stable isotopes of hydrogen and oxygen

“…Caveats to the use of isotope models-Stable isotope mass-balance models are subject to several assumptions that can influence the reliability of interpretations related to lake hydrology (Gibson 2002;Gibson et al 2005;Wolfe et al 2007). In our case, we assumed that prairie lakes were influenced mainly by precipitation and evaporation (i.e., steady state) because each lake lacked visible river influence (terminal or isolated basins), remained permanently inundated (no intermittent wetlands), and exhibited residence times .10 yr, when known.…”

“…We approximated the relative influence of summer precipitation vs. winter precipitation by determining the perpendicular distance of each basin to the theoretical LEL using the 2004 spatial survey data and following the procedures of Wolfe et al (2007). In lakes without groundwater, positive values represent conditions in which surface waters are more similar to the isotopic values of summer rainfall (d Psummer ) than would be expected from the amount-weighed input of precipitation, whereas negative values suggest that lake water is more characteristic of winter precipitation (d Pwinter ; Fig.…”

“…In principle, analysis of stable isotopes of hydrogen (d 2 H) and oxygen (d 18 O) can be used to quantify the main fluxes of water to and from lake basins (Gibson et al 1993;Gibson and Edwards 2002;Wolfe et al 2007). In this approach, ratios of light ( 1 H, 16 O) and heavy isotopes ( 2 H, 18 O) are measured in regional precipitation (summer, winter), groundwater, and surface waters (rivers, lakes, wetlands) to determine the relative importance of source waters to the hydrology of individual basins, as well as the relative influence of evaporation and water inflow in maintaining a steady-state mass-balance of water in closed basins (reviewed in Gibson et al 2005).…”

Water stable isotopes in the Yarlungzangbo headwater region and its vicinity of the southwestern Tibetan Plateau

“…The extent of heavyisotope enrichment in residual liquid phase during evaporation and the slope of the local evaporation line (LEL) are primarily controlled by local atmospheric conditions (e.g. temperature, relative humidity and isotopes in ambient atmospheric moisture) (Craig and Gordon, 1965;Gat, 1996;Gibson, 2002Gibson, , 2016Wolfe et al, 2007). The predicted LEL can be defined using an isotope mass balance model and can be potentially used to assess the connectivity of various water bodies and changes in input.…”

Clusterization of Surface Water Quality and Its Relation to Climate and Land Use/Cover

“…PC-2 indicated three correlated parameters (i.e., TC, DOC, and TP). This could be an indi- cator of natural and anthropogenic mineralization of water quality [26,27]. In this category, two parameters (i.e.…”