🌊Long Term Benthic Research Program

Understanding the impact of adding material to the benthic region is crucial. To address this, we established a long-term benthic research program. This program focused on quantifying the degradation rates and other impacts of introduced biomass on benthic ecosystems, which is essential for verifying carbon removal and understanding the broader ecological effects of our interventions. Our research involved several key experiments and work that we discuss below.

Iceland Coastal Benthic Experiment

Started in June 2023, this experiment monitors the impact of deposited biomass on the benthic environment at Hvalfjörður. Water and sediment samples are collected routinely to analyze the effects on ocean and sediment chemistry, microbial communities, and local fauna. The purpose of doing an experiment in shallow waters was not only to understand the impacts on the benthic environment, but also to better develop experiment designs, refine sampling procedures, and establish collaborations with institutions for sample processing. Preliminary results show no significant impacts on pH, total alkalinity, calcium, or organic carbon levels.

AWI Collaboration:

Initiated in June 2023, this experiment intended to test the degradation rate of carbon buoy materials at approximately 4000 meters depth in the Arctic. In collaboration with the Alfred Wegener Institute, this study was designed to assess environmental impacts of placing macroalgae in the benthic environment after one year, with potential for further studies based on initial findings.

We paused planning for this experiment due to regulatory uncertainty.

Clayoquot Slope Experiment:

Since September 2023, this experiment actively monitors the degradation and ecological impact of carbon buoy materials at approximately 1300 meters depth. Using real-time data transmission, we analyze macrofauna and microbial community composition. In collaboration with Ocean Networks Canada, we have a sampling procedure designed to capture changes in carbon and nutrient content in surrounding sediment.

Modeling of terminal density of deployed materials

As part of our Ocean Modeling work, we used a lagrangian simulator called Ocean Parcels to determine the terminal distribution of deployed material on the seafloor.

Final modeled densities from our first deployment season provided a starting point for future research.

Modeling of benthic biogeochemistry

Running Tide engaged NIVA (The Norwegian Research Institute for Water and the Environment) to assess the biogeochemical impact of our planned deployments. The institute wrote a model- and literature-based assessment for Running Tide, which was then presented at the European Geosciences Union General Assembly in 2024. The goal of this work was to assess the environmental impact of woodchip and calcium carbonate deployments in the Norwegian Sea as a marine carbon dioxide removal (mCDR) approach. For this the 2-Dimensional Benthic Pelagic Model (2DBP) was used, coupled with biogeochemical Bottom RedOx Model (BROM). In this study the maximum weight of wood chips that can be accumulated on the seafloor without dramatic changes was evaluated, focusing on the oxygen regime, acidification and biogeochemistry that can negatively affect the local ecosystem. The report consisted of three efforts:

  1. A review of the available literature as it relates to specific risks (Sections 1.2, 1.3 and summarized in Table 7.2)

  2. The development and application of a biogeochemical model (Sections 0 and 3)

  3. Discussion of the model results.

The model was used to evaluate the maximum amount of wood chips that could be added to the benthic (or seafloor) environment before leading to adverse impacts to oxygen and acidification in benthic water. The model was conservative, as it did not account for drifting in the surface water before sinking (Running Tide wood chips float and disperse on the surface for hours to weeks before sinking). The model shows that deploying 2000 metric tonnes of wood chips in 24 hours in 1 km2 surface area with no dispersion is the recommended threshold for the studied area. The results show a benthic density of 3600 gC/m2 and 5 mm deep is still within good water quality. For reference, the density of wood chips on the seafloor during the 2023 deployments from Iceland was modeled to be, at a maximum, 30 gC/m2 and ~0.06 mm deep.

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