Interactive

Finding the clues – inputs and lake sediments

Find out how different materials – known as inputs – make their way into a lakebed and become sediments. Scientists can sample the sediments to look for clues to the lake’s past and find out how it has changed over hundreds and sometimes thousands of years. This interactive also has links to Hub resources that provide background information about some of the inputs.

To use this interactive, move your mouse or finger over any of the labelled boxes and select to obtain more information. The article Lake sediment cores – exploring the past provides additional background information.

Interactive background image, all pop-up images and some of the text are courtesy of Lakes380 – Our lakes’ health: past, present, future.

Transcript

Atmosphere inputs

Pollen, dust, charcoal, volcanic ash and chemicals suspended in the atmosphere fall into the lake and over time sink to the lakebed.

Particulates can come from natural sources or they can be artificially produced.

Related resources

  • Air quality – article about particulates suspended in the air

  • Exploding Taupō – article about eruptions that sent out ash and pumice, which are used as evidence when dating sediment cores

  • Ice ages unearthed – article about using pollen and volcanic ash to date sediment cores

Atmosphere inputs illustration by Lakes380 is licensed under CC BY-NC-SA 4.0.

Catchment inputs

Rivers wash soil, nutrients (nitrogen and phosphorus), natural materials (leaves), toxins (herbicides) and human-made materials (microplastics) into lakes. Over time, these sink to the bottom.

A lake catchment is an area of land and the water that flows into a lake. A catchment is often bordered by hills or mountains.

Catchments influence the biodiversity and ecology of a lake system. Light, water temperature, pH, nutrient levels and substrate affect the plants and animals living in the water. Some of these features change naturally over time. Human influences – like making changes to the catchment area – often have substantial impacts.

Related resources

Catchment inputs illustration by Lakes380 is licensed under CC BY-NC-SA 4.0.

Lake inputs

Dead plants and organisms – for example, bacteria, algae, fish and zooplankton – that once lived in the lake sink to the bottom where they start breaking down.

Related resources

Lake inputs illustration by Lakes380 is licensed under CC BY-NC-SA 4.0.

Groundwater inputs

Nutrients and toxins from the land filter through the soil into the groundwater. These inputs travel in the groundwater, and once in the lake, the nutrients and toxins sink to the lakebed.

Wai and whenua are interconnected. Water moves down through the soil via a process called leaching – carrying the contaminants with it. Groundwater eventually discharges to surface water such as a lake.

Related resources

Groundwater inputs illustration by Lakes380 is licensed under CC BY-NC-SA 4.0.

Acknowledgement

This resource has been developed in collaboration with Lakes380 – Our lakes’ health: past, present, future (C05X1707), Cawthron Institute and GNS Science.

Rights: The University of Waikato Te Whare Wānanga o Waikato
Published:09 February 2023