Our ākonga/students continue to learn more about water chemistry. Exactly how this relates to floating wetlands is becoming clear as we explore the different aspects of this work.
Whakatane Intermediate School finished the first part of their experiment – looking at three different growing mediums. Medium A, B and C all have 50% coco-fibre and 10% compost; the remaining 40% is pumice sand [A]; high carbon organic matter [B]; local topsoil [C]. Students are monitoring what effect each growing medium has on the water quality (chemistry) of water from the Otamakaukau/Awatapu lagoon.
The Intermediate students now will join the other schools in growing wetland plants as part of their experiment. The water in the tubs will be changed regularly, and samples will be analysed for water chemistry and bacteria at each change. Their questions are: What impact might plant species have lagoon water quality; How do growing mediums impact plant growth.
Te Kura o Te Paroa ākonga are carrying on with measuring plant growth in each of the soil mediums (the same mix as for the Intermediate school). Despite winter chills, the plants have grown.
They will now look at what impact the plants have on water. At Paroa we are growing the plants in tap water, so we starts with no measurable contaminants - if we find contaminants after a couple of weeks of the plants sitting in the water, we have three possible sources – plants, growing medium or the atmosphere. Previous research gives us guidance on what can be expected to be deposited from the atmosphere, so we hopefully can account for this.
The findings from the Intermediate school will guide our understanding of changes in water quality as a result of the plants and/or mediums.
Both schools have had the Bay of Plenty Regional Council scientists Vanessa Cotterill and Rigo Medina come and work with them. This was great for all of us giving students access to working scientists and the scientists the ability to work with engaged and eager to learn students.
Te Kauwhata College students have been really busy. Plants are growing and water testing has intensified. Senior students have a lot on this term to get ready for completing their NCEA work. This hasn’t stopped us all from making the most of the time we have spent together in person.
Students learnt a lot about water quality, and what impacts water quality in their local catchment. We have had a huge amount of help and information from Mat Allan, the Waikato Regional Council Lakes Scientist, to give us the full picture of what is happening in the shallow lowland lakes of the Waikato.
An experiment is being run with “pilot wetlands”, plants growing in semi-controlled conditions, using Ta Kauwhata Pond water (which we sample every month) in a simulation of a floating wetland. There is water beneath and all around the plants, but they are held in big plastic tubs. All the plants are being grown in medium A [50% cocofibre, 10% compost, 40% pumice] as we try to isolate the impact of the plants on the water. We are testing mānuka and a carex/juncus mix.
We tested intensively (6 samples in the first week, weekly samples there after) during a 4-week period in July-August, to establish the rate of natural die-off of E.coli. At the EcoQuest Lab we used Colilert-18 as a reagent, and incubated all samples at 35 degrees C for 18 hours in Quantitray 2000 trays. We hope to find out how long it takes E.coli to die off naturally, and if there is a difference in time of die-off with/without plants in the water, particularly the mānuka (as this has been shown to remove bacteria from subsurface water in experiments run by ESR). Remember, mānuka is known as a potential phytoremediation plant because of its ability to kill off bacteria in freshwater😊. Later this year we repeat this whole process so that we have a winter and spring/summer round of intensive sampling.
The students are now focused on evaluating the methods used, presenting, and interpreting the results. This all needs to be done this term so that the students can use the work for part of their NCEA assessment. Mat Allan and Liz Tupuhi will be working with teacher McKenzie Holman and the students as they go through this process.
Sadly, due to their NCEA commitments we won’t see much of the senior students for the remainder of the Term. But we are taking the opportunity to bring the year 7 and 8 students into the project so that they can become our tuakana as the project develops over the next few years. Of course, for those senior students who come back next year (please come back – you know you want to and I’ll cook more cake) we can have some more time with you all.