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Practical analysis and data interpretation for water

Using resources • Earth's resources and potable water

Key concepts

What you'll likely be quizzed about

  • Representative sampling selects a sample that accurately reflects the water source.
  • Incorrect sampling methods can lead to biased results, especially when sampling near point sources or after rainfall.
  • Clean, labeled containers help avoid contamination, which can alter ion concentrations and pH.
  • Recording the location, time, and visible conditions affects data interpretation.
  • Safety procedures are crucial to minimize risks during analysis, including using personal protective equipment, proper waste disposal, and knowing emergency actions.

Flashcards

Test your knowledge with interactive flashcards

Define representative sampling and explain one cause of biased water samples.

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Representative sampling selects a sample that reflects the source composition. Bias can arise from sampling near point sources or after rainfall, leading to concentration variations.

Key notes

Important points to keep in mind

Collect samples in clean, labeled containers; record time, location, and visible conditions.

Calibrate pH and conductivity meters before use; note standards and calibration date.

Treat pH as logarithmic; a unit change signifies a tenfold change in [H+].

Use conductivity as a fast proxy for TDS, but confirm specific ion composition when critical.

Conduct gravimetric residue measurements for accurate TDS when volatile solutes are absent.

Expect distillation to effectively remove non-volatile solutes; watch for co-distillation of volatile contaminants.

Check axes, units, and scale (linear or logarithmic) when interpreting graphs and charts.

Compare values with common units and consider sampling times to avoid misleading trends.

Apply orders of magnitude to prioritize actions; differences of ≥2 orders often indicate major significance.

Account for measurement uncertainty and detection limits before forming conclusions.

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