Background

The Werribee River is a perennial river running from Daylesford to Werribee South, where it enters Port Phillip. It supports a variety of animal and plant life, including the endangered Growling grass frog, and is used for irrigation in the food producing region of Bacchus Marsh. Therefore, water quality tests are conducted regularly by water agencies to ensure the ongoing health of the waterway. A variety of parameters may be measured to provide an overall water quality rating including pH, salinity, temperature, dissolved oxygen, nitrogen (as nitrates), phosphorus (as phosphates), turbidity and metal concentrations.

Metals play an important role in water chemistry and water quality. Some metals are toxic at high concentrations whilst others play an essential role in water systems. Atomic absorption spectrometry (AAS), developed by Australian scientist Sir Alan Walsh, may be used to detect unknown concentrations of ~70 metals by comparing with calibration curves constructed using standard solutions. Analytical chemistry techniques used in the field and the laboratory compliment each other to provide comprehensive water quality datasets.

Prior Knowledge

No prior knowledge required.

Learning Intentions

In this program students will:

• Learn about the potential sources of contaminants in our waterways.
• Use a variety of equipment and techniques to undertake quantitative analyses of water samples from the Werribee River.
• Develop an appreciation of how field- and laboratory-based chemists can use different and complimentary testing methods to determine water quality.
• Consolidate their understanding of the properties of metallic ions by undertaking qualitative analysis of metals using flame tests.
• Use their stoichiometry and graphing skills to make up standards and plot a calibration curve to determine the concentration of sodium in water samples.
• Develop their laboratory skills and identify common sources of experimental error.

Activities

In this program students will:

• Use field based (pH and conductivity meters, colorimetry, titration kits) and laboratory based (atomic absorption spectrometry) techniques to analyse water samples from the Werribee River.
• Perform calculations to prepare sodium standards and use these standards to construct a calibration curve.
• Interpret and comment on their results by comparing them with published water quality standards.

Learn Online

Ecolinc Learn Online is a virtual outreach learning management system (LMS) offering interactive online courses for students and teachers. These courses can be undertaken either as a pre-visit, post-visit or stand-alone.

Students are encouraged to do the pre-learning course on Ecolinc Learn Online called Safe Labs prior to coming to Ecolinc. In this course students will cover all the necessary aspects of laboratory safety during their time at Ecolinc. When planning any work in a laboratory the risk of exposure to laboratory hazards is an important consideration. This course is part of Ecolinc’s risk minimisation for student safety.

VCE links

Area of Study 2: How are chemicals measured and analysed?