In October 2015, GBF’s David Sweetnam met University of Toronto Associate Professor Maria Dittrich in Honey Harbour to help her research measuring the make-up of the sediment, and its capacity to release Phosphorous into the water.
It’s important research as freshwater with high Phosphorous is linked with an increased risk in toxic algal blooms.
We asked Professor Dittrich some questions about her research, and have included extra information marked GBF to explain some of the details.
How does your research support protecting and enhancing the waters of Georgian Bay?Professor Dittrich:
Phosphorus is the typical limiting nutrient for primary production or algae growth in freshwater ecosystems, where high Phosphorus inputs are linked with an increased risk of algal blooms dominated by potentially harmful cyanobacteria (CHABs).
We are using field and modelling studies to predict sediment Phosphorus mobilization and its impact on water quality and the risk of CHABs, based on robust measures and a modelling framework that we have successfully developed and applied elsewhere.
GBF help info:
Nutrients like Phosphorus and Nitrogen are essential for the development of algae, which forms the basis of the aquatic plant and animal food chain. However, when there are excessive nutrients present, too much algae and other aquatic plants thrive uneaten.
This has several negative affects including:
- Algal blooms. What are they? A speedy growth in the density of algae. Some algal blooms are comprised largely of cyanobacteria (blue-green algae). Some of these blooms can be toxic, while some aren’t.Non-toxic algae can also be problematic due to…
- Lack of Oxygen. When the over abundance of algae and plants die, oxygen in the water is consumed by the micro-organisms that break it down. Lack of oxygen can lead to the death of a lot of aquatic life.
This study provides the first direct measures of internal nutrient loading and sediment chemistry in Georgian Bay embayments, and assess links with anoxia and CHABs.
GBF help info:
- What is internal nutrient loading? It is the releasing of nutrients into the water from lake sediment, or the muddy bottom layer. While excess nutrients (eutrophication) can come from external sources like wastewater, agriculture, drainage water, and erosion – a large part can come from the sediment layer release. Nutrients build in the sediment from the past decay of algae and other organic materials.
- What is anoxia? Not enough oxygen.
- What are CHABs again? Cyanobacteria, sometimes called blue-green algae – which in certain conditions can be toxic.
2. How do you do your work? What is the process? What are you collecting?Professor Dittrich:
We are collecting and analyzing samples from both sediment-water interfaces and sediment. In particular, we focus on the depth profiles of concentration of alkalinity, dissolved Phosphorus, nitrate, Fe, Al, Mn, Ca and Si in the upper 30 cm sediment at the cm-scale and oxygen, pH, and redox potential at the sediment water interface at the micrometer scale.
Pore water data in the upper sediment are collected using so-called “Rhizons”, while the sediment cores are collected with a gravity corer (UWITEC) and Plexiglas core tubes, 5.5 cm in diameter. High-resolution profiles will be obtained using a Mini Profilter from Unisense (Denmark), which has a high spatial resolution (50 μm) and includes oxygen, pH, and redox potential microsensors. The Phosphorus fractionation of selected sediment layers will be performed based on “Psenner” method following the Dittrich’s (2013) protocol.
3. What do you hope to achieve from this work beyond Georgian Bay?Professor Dittrich:
In combination with external loading data from other studies, our results will allow an evaluation of the relative importance of internal loading and how this may affect and/or /delay responses to management/remedial action. Our study addresses an important knowledge gap, and will contribute to more effective management of this region – with direct relevance to Lake Simcoe and other water bodies.
The model will predict both Phosphorus fluxes from sediment and sediment depth profiles of oxygen, total Phosphorus, Phosphorus binding forms (e.g., bioavailable and redox-sensitive Phosphorus) and total carbon.
A direct and accurate estimation of nutrient fluxes from sediments and sediment-oxygen demand will significantly improve the ability of managers to assess and implement management strategies to control nutrients and hypoxia.
GBF Help info:
What is hypoxia? Not enough oxygen, in this case in the aquatic environment.
Data collected through this project is important for model development and validation. This study addresses the knowledge gap surrounding the factors that contribute to bloom events and nutrient fluxes from sediment into water column in embayments of Georgian Bay.
4. How has the partnership with Georgian Bay Forever helped facilitate your work?Professor Dittrich:
This partnership is critical and essential for both field and modelling parts of our research program.
Due to our cooperation with GBF, we were able to collect our samples and perform the microsensor measurements in Honey Harbor, which will be impossible without our partnership.
Furthermore, the data from the GBF paleolimnological study was used to calibrate the diagenetic model, and to develop a Phosphorus balance estimation.
5. When do you anticipate finalizing the results of your research?Professor Dittrich:
Our research project is funded for three years that started in 2014. We are going to publish the results of our field studies during first two years in 2016. The final report will be submitted by May 2017.
Our thanks to Associate Professor Maria Dittrich and her associates Stefan Markovic, Research Assistant at University of Toronto, Sandra Cadena, PHD student, and Dr. Phoung Doan who is in charge of modelling.
Most of all, thank you for your support of Georgian Bay Projects that help to protect the water.
You can support projects like these by making a donation to Georgian Bay Forever.
Get to know Professor Maria Dittrich:
Maria Dittrich received a Master Degree in Physics with distinction from Moscow State University Russia and PhD in Aquatic Ecology, Institute for Freshwater Ecology and Fisheries, Berlin, Germany. She is now Associate Professor at the University of Toronto Scarborough, Canada. Over the past several years, Professor Dittrich both initiated and collaborated on several projects focused on biogeochemistry. She has published about 50 papers, wrote two book chapters, among them Application of an infrared spectroscopy for cell-minerals interfaces, 2012, Ali Navid (ed.), Microbial Systems Biology: Methods and Protocols, Methods in Molecular Biology, Vol. 881, Springer, 187-211. Professor Dittrich’s research approach involves a combination of a wide range of analytical tools with field and modelling studies of freshwater ecosystems. Her research group applies Atomic Force and electron microscopy, as well as conventional and synchrotron-based spectroscopy (infra-red, electron energy loss; EELS, near-edge x-ray absorption fine-structure; NEXAFS). She teaches various courses related to Geomicrobiology at the University of Toronto, as well as a private-docent at the ETH (Swiss Federal Institute of Technology), Zurich, Switzerland. Recently, she has been invited to teach a course in Geobiology for Petrobras, the Brazilian state-owned oil company.
Sources used by Georgian Bay Forever in this post:
“Where Nutrients Come From and How they Cause Entrophication”. United Nations Environment Program. Retrieved October 15, 2015 at https://www.unep.or.jp/ietc/publications/short_series/lakereservoirs-3/3.asp
“Nutrients in Lakes and Streams”. Water Encyclopedia. Retrieved October 15, 2015 at https://www.waterencyclopedia.com/Mi-Oc/Nutrients-in-Lakes-and-Streams.html
“Understanding algal blooms”. St.John’s River Water Management District. Retrieved October 15, 2015 at http://floridaswater.com/algae/