Developing and applying control charts to detect changes in water chemistry parameters measured in the Athabasca River near the oil sands: A tool for surveillance monitoring

Abstract

Control charting is a simple technique to identify change and is well suited for use in water quality programs. Control charts accounting for covariation associated with discharge and in some cases time were used to explore example and representative variables routinely measured in the Athabasca River near the oil sands area for indications of change. The explored variables include 5 major ions (chloride, sodium, sulfate, calcium, magnesium), 5 total metals (aluminum, iron, thallium, molybdenum, vanadium), and total suspended solids at two sites straddling the developments north of Fort McMurray. Regression equations developed from reference data (1988-2009) were used to predict observations and calculate residuals from later test data (2010-2016). Evidence of change was sought in the deviation of residual errors from the test period compared with the patterns expected and defined from probability distributions of the reference residuals using the odds ratio. In most cases, the patterns in test residuals were not statistically different from those expected from the reference period at either site, especially when data were examined annually. However, differences were found at both locations, more were found at the downstream site, and more differences emerged as data accumulated and were analyzed over time. In sum, the analyses at the downstream site suggest higher concentrations than predicted in most major ions, but the source of the changes is uncertain. In contrast, the concentrations of most metals at during the test period were lower than expected, which may be related to deposition patterns of materials or weathering of minerals during construction activities of the 2000s which influence the reference data used. The analyses also suggest alternative approaches may be necessary to understand change in some variables. Despite this, the results support the use of control charts to detect changes in water chemistry parameters and the value of the tool in surveillance phases of long-term and adaptive monitoring programs. Environ Toxicol Chem 2018;37:2296-2311. © 2018 SETAC.

Long‐Term Studies of Fish Health before and after the Closure of a Bleached Kraft Pulp Mill in Northern Ontario, Canada

“…This may be most clearly demonstrated by the greater than expected gonad weight observed in females at all sites sampled in 2011. Similar challenges have been identified in other analyses over time (Arciszewski et al 2018) and have implications for retrospective investigations of cause using indicators sensitive to environmental covariates (Arciszewski et al 2017) and separating sources of variation into "assignable" and "unassignable" categories (Montgomery 2007). However, accounting for some factors, such as climatic influence, can be anticipated and addressed prospectively.…”

“…Following the example of Walshe et al (2007) and the statistical evaluation of odds ratios (e.g., Arciszewski et al 2018), 2 criteria were used to ascribe the status of the measurements of fish population performance used in the present study ( Figure 2). The 2 attributes of the observations are the position of the observed median of residuals and the magnitude of its 95% CIs relative to the expected ranges of the medians of residuals calculated from the relevant reference set.…”

Potential Influence of Sewage Phosphorus and Wet and Dry Deposition Detected in Fish Collected in the Athabasca River North of Fort McMurray

“…This contention is supported by additional research [35,83] and by additional data available for the region. On average, 90% of flow present in the Athabasca River at the Embarras Airport gauging station (DD001) which is downstream of all development [84] is already present in the channel when river water reaches the gauging station at Fort McMurray (Supplementary Figure S5). However, this value ranges from 33 to 129% (Supplementary Figure S5).…”

Overview of Existing Science to Inform Oil Sands Process Water Release: A Technical Workshop Summary

“…For example, monitoring of potential impacts of discharges will require understanding conditions in the receiving environment, including both discharge and reference areas, prior to any release. Consideration of the appropriateness of the data set to understand the statistical power to detect differences, to support interpretation of environmental effects monitoring, and to define tiers and triggers for various measurement and assessment endpoints (e.g., Arciszewski et al ; Somers et al ) is necessary for the design and implementation of the monitoring programs (Arciszewski et al ).…”