pH stands for Potential Hydrogen and is a measure used to express the acidity or basicity of an aqueous solution, on a logarithmic scale. pH of 7 is a denotation of “neutral” in that the solution is neither acidic nor basic.
In environmental systems, pH is extremely important as the flora and fauna in the system will be adapted to a “normal” pH range; if the water starts experiencing pH outside of this range this can cause stress to the system and death of aquatic life.
pH is also important as it changes the solubility and toxicity properties of both chemicals and heavy metals in the water. For example, research has shown that lower pH levels increase the solubility of heavy metals in soil sediments, therefore allowing them to propagate into the water and become bioavailable, causing them to be propagated into the food chain.
Even slight changes in pH can affect the solubility of nutrients such as nitrogen and phosphorus, making them more available for use in plant growth which can cause eutrophication.
pH is also an important consideration in drinking water with the general accepted pH level for consumption is 6.5-8.5.
pH measurement will typically involve measuring the hydrogen ion activity of the solution under question to a stable reference solution. pH is measured using electrodes to detect hydrogen ion concentration and the compare this to a reference solution.
The Proteus uses a glass bulb sensor where the glass surface detects hydrogen ion concentration, transforming this to a voltage. This is then compared with a refillable reference electrode solution. The reading is also temperature corrected.
The Proteus offers the option of including a platinum ORP sensor with the pH sensor.
