DOI: 10.5061/dryad.0zpc8675s
title: Data for: Stable isotope-inferred hydrology of ponds created by the Mount St. Helens eruption

description: Freshwater ponds are prevalent globally and provide critical ecosystem
 functions (e.g., water storage and groundwater recharge), yet little is
 known of their hydrological features immediately following
 formation.  We analysed stable isotopes of water (δ2H, δ18O) to
 characterize spatio-temporal hydrologic variation in ponds created by the
 Mount St. Helens eruption.  We also examined how climate and
 landscape features interact to regulate local hydrology.  Ponds
 were sampled for isotopic analysis in spring (2015, 2017, 2018) and summer
 (2018).  Mass balance models characterized the water balance of
 ponds (evaporation: inflow; E:I), as well as water sources (rain,
 snow).  Other variables were measured in situ (temperature,
 conductance), collected from data sources (meteorology), or quantified
 with remote sensing (vegetation).  Bayesian estimates of standard
 ellipse areas (SEAB) were used to compare isotopic values among years,
 whereas linear models were used to examine local and regional drivers of
 E:I, as well as intra-annual isotopic shifts.  We observed high
 inter-annual variability (as SEAB), suggesting that snow was the main
 water source in wet years, but that the proportion of rain and snow varied
 among sites in dry years.  Spring E:I was negatively correlated
 with total precipitation, whereas the importance of evaporation in summer
 varied with pond morphology, with large shallow ponds exhibiting the
 greatest evaporation. Evaporation regulated the hydrology of ponds with
 higher dissolved organic carbon (DOC; as residuals of DOC and
 chlorophyll).  We show that simple metrics of basin morphometry
 can predict seasonal variability in pond hydrology, allowing managers to
 better estimate pond sensitivity to future climate conditions.
description: There are two datasets included: 1) environmental data; and 2)
 isotope data.  Variables in the environmental dataset
 were collected several ways, including in situ measurements (water
 temperature, specific conductance), analyzed in a laboratory following
 sampling (dissolved organic carbon), compiled from outside data sources
 (meteorological variables), or quantified with remote sensing (normalized
 difference vegetation index).  Data processing is described in the
 manuscript. Variables in the isotope dataset were
 analyzed in a laboratory following sampling (δ<sup>2</sup>H
 and δ<sup>18</sup>O), compiled from outside data sources
 (meteorological variables), or represent intermediate calculations. 
 Briefly, water samples were collected by immersing high-density
 polyethylene bottles, which were then sealed tightly to prevent water
 evaporation.  Samples were filtered through glass fiber filters (VWR,
 0.45-µm pore size) on the day of collection, and the filtrate frozen until
 for further chemical analysis.  Water samples were analyzed for
 δ<sup>2</sup>H and δ<sup>18</sup>O values using a
 Picarro L2120-I cavity ring-down spectrometer (CRDS), at the Institute of
 Environmental Change and Society (IECS), University of Regina,
 Saskatchewan, Canada (http://www.iecs-uregina.ca/).  All isotope results are reported in δ notation in per mil units (‰) relative to local and international standards, including Vienna Standard Mean Ocean Water 2 (VSMOW2) and Standard Light Antarctic Precipitation 2 (SLAP2).  
description: # Data for: Stable isotope-inferred hydrology of ponds created by the
 Mount St. Helens eruption
 [https://doi.org/10.5061/dryad.0zpc8675s](https://doi.org/10.5061/dryad.0zpc8675s) Datasets consist of environmental data and isotope data. ## Description of the data and file structure Missing data indicated with NA. **environmental_data_final.csv** uniqueID – a unique sample identifier to join environmental dataset with isotopic dataset      date – sample date; MM/DD/YYYY year - sample year         pond – name of pond (M: Maratta region; H: Hummocks region)            region – Hummocks or Maratta               elev_m - elevation of ponds, derived from GPS measurements taken from pond shore; meters lat – latitude of ponds, from GPS coordinates taken from pond shore; decimal degree               long – latitude of ponds, from GPS coordinates taken from pond shore; decimal degree                           hydroperiod – categorical classification of pond hydroperiod  depth_cm – maximum depth of ponds; centimeters    area_m2 – surface area of ponds; meters^2     temp_water_C - surface water temperature of ponds, collected with a YSI ProPlus; degrees Celsius spC – surface specific conductance of ponds, collected with a YSI ProPlus; μSiemens/centimeter    avg_wind_m_sec_1mo – average wind speed in the 1 month prior to sampling, obtained from US Forest Service Canyon Creek, Washington, weather station; meters/second avg_temp_C_1mo - average daily air temperature in the 1 month prior to sampling, obtained from US Forest Service Canyon Creek, Washington, weather station; meters/second tot_ppt_mm_1mo - total cumulative precipitation in the 1 month prior to sampling, obtained from US Forest Service Canyon Creek, Washington, weather station; millimeters mean_ndvi – mean normalized difference vegetation index (NDVI) of the nearshore region within a 100-m buffer; unitless               DOC_ppm – surface dissolved organic carbon concentration from ponds; mg/L pond_cc_pct – pond canopy cover; % **isotopes_final.csv** uniqueID – a unique sample identifier to join environmental dataset with isotopic dataset      date – sample date; MM/DD/YYYY         year - sample year         pond – name of pond (M: Maratta region; H: Hummocks region)            region – Hummocks or Maratta top – isotope sample taken from pond surface (y: yes; n: no) bottom – isotope sample taken from near pond bottom (y: yes; n: no) season – season that sampling occurred; spring or summer H - δ2H of pond sample; per mille (‰) O - δ18O of pond sample; per mille (‰) d.excess – index of evaporation (see text for details); unitless lc.excess – line-conditioned excess, an index of evaporation (see text for details); unitless gmwl.H – global meteoric water line; δ2H = 8*δ18O + 10; per mille (‰) deltaP.H - δP the isotopic composition of precipitation for δ2H, values vary based on season (see text for details); per mille (‰) deltaP.O -  δP the isotopic composition of precipitation for δ18O, values vary based on season (see text for details); per mille (‰) avg.temp.K – average daily air temperature in the month that sampling occurred, obtained from US Forest Service Canyon Creek, Washington, weather station; Kelvins (K) avg.RH.pct – average daily relative humidity in the month that sampling occurred, obtained from US Forest Service Canyon Creek, Washington, weather station; percent (%) EI – evaporation:inflow ratio; unitless