FORMBLOOM: FORecasting tools and Mitigation options for diverse BLOOM-affected lakes (2017-2023) Freshwater lakes and reservoirs across Canada provide numerous services for local communities ranging from drinking water to recreation. Unfortunately, these same ecosystems are susceptible to a changing climate and nutrient loading. Cyanobacteria, a common photosynthetic group of microbes in freshwater lakes, are known to grow in excess (or bloom) when nutrients loads are high. Under these conditions, cyanobacteria may have detrimental effects on human, animal, and ecosystem health.

Solving the problem of blooms requires an understanding of how the physical environment links to geochemistry and bloom ecology, and this understanding must exist on the timescale upon which blooms develop and collapse – minutes to hours to weeks. And while solving blooms is a grand challenge, managing their impact is a key interim goal. This project is designed to address key environmental factors that drive bloom onset, duration, and cessation while also evaluting the impact blooms have on ecosystem services. This is a GWF-funded project.

Natural Stable Isotopes of Iron: A new tool to trace Fe cycling for management of risk from harmful cyanobacterial blooms in lakes and reservoirs (2016-2020)

Natural stable isotopes of iron contain information about the source of iron required to fuel cyanobacteria blooms. Our recent work has shown the importance of reduced iron to cyanobacteria in embayments along Georgian bay in support of our conceptual model that links anoxia, phosphorus, nitrogen , iron, and sulphate to cyanobacteria blooms. Following the surprising results in our 2017 paper that showed intriguing patterns between the a) terrestrial and lake surface waters, b) between dissolved and particulate pahses throughout the lake waer column, and c) between the lake surface and bottom, we are employing iron (and carbon and nitrogen) isotopes to look at the relative importance and timing of Fe sources and processes in Canadian shield lakes. This is an NSERC-funded project.

SAMMS: Sub-Arctic Metal Mobility Study (2018-2021) There is legacy metal pollution from mining across the Northwest Territories. Changes in dissolved organic matter and hydrology due to climate change will alter how these metals move through the environment. SAMMS will trace the transport and behaviour of dissolved organic matter and metals through terrestrial and aquatic ecosystems in headwater catchments along a 200 km airshed transect between the Giant Mine in Yellowknife, NWT and Whatì, an area of concentrated mining activity. Findings will inform improved decision-making by multiple stakeholders in the NWT, including Indigenous peoples, about the both legacy of mining activities and implications of new mining developments on water quality in a changing environment. This is a GWF-funded project.

Nitrate Cycling in Streams, Rivers, and Lakes (ongoing)

The ubiquity of nitrogen pollution in rivers and lakes has caused water quality to decline and altered the ecological structure and function of water therein. Many nitrogen species, e.g. (NH4+), nitrate (NO3-) and nitrite (NO2-) are harmful to aquatic organisms and can make disinfection of potable water difficult. A combination of factors, such as population growth, agricultural intensification and changing precipitation patterns, has lead to increased nitrogen loading to surface waters.

In the Grand River, Ontario, Canada, some of this nitrogen is lost to denitrification since high observed N2O concentrations are strongly linked to low O2 concentrations. Metabolic rates, primary production and respiration, are very high and diel ranges in both O2 concentrations and stable isotopes (18O/16O) of O2 values are large. Together these results indicate nitrogen turnover rates are rapid but vary at different points in rivers. Recent work on the isotope systematics of the nitrogen cycle demonstrate that greater understanding is required on nitrogen isotope fractionation during uptake and assimilation and new experimental approaches are required to decipher oxygen isotopes because of the role of H2O molecules in altering the δ18O values of NO3-. The δ18O values of NO3- in rivers are lower than traditional calculations would suggest for NO3- This makes interpreting these δ18O values difficult, at face value, because they are often used together as an indicator of denitrification. This is NSERC- and IAEA-funded research.