|Water is commonly thought of as just H2O, but groundwater contains a wide range of dissolved chemical elements from the surrounding environment. Most of these occur naturally, and many are present only in small quantities. These elements can tell us a lot about the source of the water, its quality and possible uses.|
In most groundwater, typically only seven ions make up nearly 95% of all ions present. These are calcium, magnesium, sodium, potassium, chloride, sulphate, and bicarbonate. In addition, other chemical elements known as minor and trace elements usually exist in small quantities, as do particular isotopes.
What is groundwater hydrochemistry used for? The hydrochemistry of any groundwater sample has a distinct chemical signature. This signature reflects the sum of all processes that affected the water from the time it began as rainfall, infiltrated the soil above the water table, passed into the aquifer (body of permeable rock which contains and transmits groundwater), and traveled (sometimes over great distances and depth), to the point of sample collection or discharge from the aquifer.
Processes that affect hydrochemistry can provide a powerful tool for tracking groundwater flow and managing groundwater in a sustainable way. Hydrochemistry can help to answer many questions, such as ...
1. Can this water be used for drinking, irrigation or stock and domestic needs?
2. Where does this groundwater come from?
3. How long ago was the groundwater replenished?
4. How old is the groundwater?
Hydrochemistry analysis has played a major role in increasing our understanding of groundwater processes in Australia largest groundwater basin, the Great Artesian Basin. It has been used to determine the rate of groundwater flow, recharge mechanisms and rates, the age of groundwater, inter-aquifer connectivity, and to delineate flow systems within the basin. This information has been integral for the development of appropriate management of groundwater.
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