Finding the clues – inputs and lake sediments
Dust, nutrients, other natural and human-made materials enter lakes over many years. They settle to the lakebed to form sediments. This interactive explores different inputs.
Select here to view the full transcript and copyright information.
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
Water catchments – article
Water flows and catchments – interactive that curates catchment resources
Water quality in Rotorua Lakes – article about human impacts
Lake catchments – video featuring Professor David Hamilton, a limnologist who also works on Lakes380
Microplastics – article about tiny plastic pieces in the environment
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
Freshwater macroinvertebrates – article about tiny animals that live in lakes and streams
Wetland animals – article describing the diverse species that live in freshwater environments
New Zealand’s freshwater fish – article curating resources in te reo Māori and English
Pest plants – video about the impacts of pest species in aquatic ecosystems
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
Farming and environmental pollution – article about impacts on water quality
Dairy farming and the nitrogen cycle – article about inputs and outputs
Focusing on phosphorus – article about inputs and outputs
Constructing an aquifer model – activity and demonstration video that show the relationship between groundwater and surface water
Groundwater contamination – activity and demonstration videos that show how pollutants are dissolved and/or carried into groundwater and surface water
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.
Note the website is now Our Lakes, Our Future.
Lakes380 – Our lakes’ health: past, present, future
Lakes380 is a national project to gain in-depth understanding of the current and historical health of lakes in Aotearoa New Zealand. The project was co-led by GNS Science and Cawthron Institute and funded by the New Zealand Ministry of Business, Innovation and Employment (C05X1707; Our lakes, Or future (previously Lakes380.com)).
