News

A research paper by ERG group member Danielle Green published in Frontiers in Environmental Science examines the effects of winter pulsed warming and snowmelt on nitrogen cycling in agricultural soils. The field-scale lysimeter experiment results show that increased winter pulsed warming and snowmelt over the non-growing season causes increased loss of nitrogen from agricultural soils as nitrous oxide emissions in silt loam soils and nitrate leaching in loamy sand soils.

The dissolution of amorphous silica (SiO₂), including biogenic silica produced by algae and higher plants, is the key process controlling the recycling of nutrient silicon in terrestrial and aquatic environments. The rate at which amorphous silica dissolves in a particular environmental setting depends on the prevailing physical and geochemical conditions. In anoxic environments, such as water saturated soils or sediments in deeper parts of lakes, ferrous iron (Fe²⁺) ions are ubiquitous.

A new paper entitled “Pore-Scale Heterogeneities Improve the Degradation of a Self- Inhibiting Substrate: Insights from Reactive Transport Modeling” uses reactive transport modeling to analyze contaminant bioremediation in natural porous media such as soils and groundwater. The model accounts for the potential impact of substrate self-inhibition, that is, when microbial activity becomes inhibited at high concentrations of the contaminant. The results show that pore-scale heterogeneities enhance the bioremediation rate, compared to simulations in a homogeneous porous medium.

Ecohydrology Research Group (ERG) members presented their research virtually at the 49^th International Association of Hydrogeologists (IAH) Congress. Philippe Van Cappellen gave a Keynote Lecture on “Global Impacts of River Damming on Carbon and Nutrient Cycles: A Synthesis” on the final day of the congress, which was held fully online.

The first annual meeting of the Microplastics Fingerprinting project was held on the CIGI campus in downtown Waterloo. The aim of the workshop was to review the progress of the work so far and exchange ideas about further integration among the different work packages, as well as deepening collaborations with our external partners. Below is the program of the meeting.

Microplastics Annual Meeting 2022 Program

A new paper in Frontiers in Environmental Science, co-authored by Ecohydrology Research Group member Fereidoun Rezanezhad assess the impact of freezing and thawing cycles on hydro-physical properties and dissolved organic carbon fluxes from peat soils. This study illustrates how the changes in peat physical and hydrological properties during the winter conditions play important roles in water flow and nutrients export in peatlands.

A new paper is published in Water Resources Research by Anna Störiko who was a visiting PhD student in ERG in 2019. The paper is co-authored by Philippe and Adrian Mellage, formerly a PhD student in ERG. The paper presents a reactive transport model that can simultaneously predict the rates, functional-gene transcripts, and enzymes of denitrification.

Research presented in a paper authored by ERG member Jovana Radosavljevic published in Science of the Total Environment demonstrates that increasing lake salinization linked to urban growth causes water quality deterioration usually ascribed to the proliferation of algae driven by nutrient enrichment. Salinization strengthens water column stratification which, in turn, results in more oxygen depletion of the hypolimnion, and more internal phosphorus loading in the lake.

Professors Philippe Van Cappellen and Fereidoun Rezanezhad discuss how they are developing methods to better understand winter soil processes.

Read the full article here.

A paper by ERG group member Konrad Krogstad published in Frontiers in Environmental Science examines the effects of freeze-thaw cycles on nitrogen, sulfate, and chloride leaching from fertilized and unfertilized soil columns. Experiment and model results show that freeze-thaw cycles promote nitrifying conditions in the upper oxidized portion of the fertilized soil columns. The findings indicate that unwanted nitrogen enrichment in agroecosystems caused by pre-winter nitrogen fertilizer application may be exacerbated by changing freeze-thaw activity.