Groundwater Quality


August Weather Event 2022

Information relating to the recent weather event in Marlborough

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Groundwater Quality

The pages below feature graphs showing the distribution of various parameters in Marlborough groundwater.

  • Alkalinity

    Alkalinity is a measure of the ability of a groundwater to neutralise acids.

  • Ammoniacal Nitrogen

    Under anaerobic aquifer conditions, nitrate nitrogen changes its form and is converted chemically to ammoniacal nitrogen (NH3+ and NH4+).

  • Arsenic

    The presence of high levels of arsenic in Marlborough groundwater has only been discovered as recently as 2001.

  • Calcium

    Calcium is one of the most common dissolved solids in Marlborough groundwaters. This reflects its natural occurrence in many local rocks, and in particular the coastal marine sedimentary formations.

  • Chloride

    Most chloride in inland groundwaters originates indirectly from evaporated seawater that falls to earth as rain and recharges aquifers.

  • Electrical Conductivity

    Conductivity is widely used as an indicator of the total dissolved solids in groundwater.

  • Iron

    Iron and manganese are commonly found together in anaerobic groundwaters in Marlborough. Both are derived from natural water-rock processes rather than land use activities.

  • Magnesium

    The main source of magnesium in Marlborough groundwaters is likely to be from minerals in local rocks that have been eroded and then dissolved through interaction with water over geological time.

  • Manganese

    Manganese dioxide is a distinct black colour compared to the orange-brown of iron oxide, commonly known as rust.

  • Nitrate-nitrogen

    The nutrients nitrogen, sulphate, potassium and phosphorus generally occur naturally in local groundwaters to varying degrees, but can also be added by manmade processes.

  • pH

    pH is a measure of the acidity or alkalinity of a fluid.

  • Potassium

    Potassium can be added to groundwater through fertiliser use and the breakdown of animal or human waste products.

  • Sulphate

    Sulphate exists at relatively low levels in groundwaters.