DOI: 10.5061/dryad.ghx3ffbzz
title: A 140-year paleolimnological record of climatically and anthropogenically driven eutrophication in Utikuma Lake, Alberta, Canada

description: Eutrophication brings a plethora of environmental and economic
 consequences to lakes, including ecosystem degradation, increased health
 risk due to the emergence of harmful algal blooms, and disrupts tourism,
 recreation and fishing industries. A 140-year core record from Utikuma
 Lake, Alberta, Canada (55.87° N, 115.42°W), uncovered the mechanisms
 contributing to the lake's current hypereutrophic state. ITRAX X-ray
 fluorescence (XRF) element/ratios and end-member modeling analysis (EMMA)
 of the core sediment grain size data identified variation in the core
 profile linked to specific sedimentological processes. XRF results
 exhibited changes in precipitation, weathering, and catchment runoff (Ti,
 Fe, K/Rb, Ca/Sr) and in lake productivity over time (P, S, Si/Ti). Five
 derived end members (EMs) were identified: EM01 (mode = 1 µm), low-energy
 catchment erosion from moderate precipitation events; EM02 (mode = 9 µm),
 warm spring low-energy freshet; EM03 (mode = 44 µm), cold spring
 high-energy freshet; EM04 (primary mode = 84 µm, secondary mode = 42 µm),
 major storm events; and EM05 (mode = 146 µm), catchment disturbances
 related to construction earth moving. CONISS clustering analysis of EMMA
 and XRF data identified five distinct depositional phases (Zones 1–5)
 spanning from the late 19th century to the present, characterized by
 varying levels of productivity, rainfall, weathering, and runoff
 associated with both natural and anthropogenic factors. Spectral and
 wavelet time series analysis showed that Utikuma Lake's spring
 freshet has similar spectral content to time series representating the
 Arctic Oscillation (AO), El-Niño Southern Oscillation (ENSO), North
 Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO), while
 rainfall-driven sedimentary processes are mainly affected by ENSO and PDO.
 The most notable change in the record took place in 1996, characterized by
 a sudden and significant rise in both biological productivity and runoff
 from the catchment area. This shift pushed the lake beyond a trophic
 tipping point, leading to the development of hypereutrophic conditions
 that persist to this day. This limnological shift was primarily triggered
 by a significant discharge from a decommissioned sewage treatment lagoon
 into the lake. Contributing factors also included catchment runoff
 disturbances linked to phase shifts in the PDO and ENSO teleconnections.
description: Gravity cores were collected with a UWITEC corer in June 2022.
 Cores were subsampled at 1-mm resolution using a portable, high-resolution
 sediment core extruder. Subsamples were refrigerated and transferred to
 Carleton University for analysis. The subsamples were preprocessed for
 grain size analysis using a three-step digestion process to dissolve
 carbonates (addition of 10% HCl), oxidize organic matter (addition of 30%
 H<sub>2</sub>O<sub>2</sub>), and remove biogenic
 silica (addition of 0.2 M NaOH). The subsamples were then analyzed using a
 Beckman Coulter LS 13 320 laser diffraction particle size analyzer
 equipped with a universal liquid module to yield a grain size distribution
 ranging from 0.375 μm to 2,000 μm. This data subsequently used for End
 Member Modelling Analysis (EMMA), which produced five end members. The
 core material was also scanned by a Cox ITRAX XRF Core Scanner at McMaster
 University. The subsamples were homogenized and loaded into sequential
 sediment reservoir trays. They trays were then fitted into the core
 scanner and scanned using the Mo tube. 
description: # A 140-year paleolimnological record of climatic and anthropogenically
 driven eutrophication in Utikuma Lake, Alberta, Canada ---
 Paleolimnological data from Utikuma Lake, Alberta, Canada (55.87° N,
 115.42°W) is presented. This data was derived from analysis of gravity
 cores retrieved from the lake using UWITEC core barrels in June 2022.
 Grain size and End Member Modelling Analysis (EMMA) and ITRAX-XRF analysis
 were carried out on 1-mm subsamples of core BU-1. Five robust end members
 (EMs) were found. Pb-210 dating of the core BU-4 indicated that the upper
 20 cm of the cores span approximately 140 years. The sedimentary record
 from Utikuma Lake archives both natural and anthropogenically driven
 changes, including the shift towards hypereutrophication that began in the
 mid 1990s. ## Description of the data and file structure File list: File 1
 name: BU1_PSA.csv File 1 description: particle size analysis bins in
 microns and associated calendar dates for Utikuma Lake core BU-1. Grain
 size bins (n=93) range from 0.375 μm to 2,000 μm. Row 1 of the CSV file
 contain the upper limit of the grain size bin (in microns) as headers.
 File 2 name: BU1_EMMA.csv File 2 description: End Member Modelling
 Analysis (EMMA) results and associated calendar dates for Utikuma Lake
 core BU-1 subsamples. EMMA results are in percentage; all EM columns (EM01
 to EM05) for a given sample will sum to 100. Modal grain size for each end
 member is listed in the header. File 3 name: BU1_ITRAX.csv File 3
 description: ITRAX X-Ray Fluorescence results and associated calendar
 dates for Utikuma Lake core BU-1. Data includes counts per second (cps) of
 various elements, total cps, and other instrument readouts. Columns 3-12
 list instrument quality control parameters for each sample. Columns 13-74
 list cps of various elements for each sample. ## Sharing/Access
 information N/A