Browsing by Subject "carbon dioxide"

Now showing 1 - 7 of 7
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    Acoustic and chemical conditioning and retention for behavioral deterrence in invasive bigheaded carps (Hypophthalmichthys molitrix and H. nobilis)
    (2023-05) Culotta, Jackie
    Invasive bigheaded carps (Hypophthalmichthys molitrix and H. nobilis) are two aquatic invasive species that are expanding their range throughout the Mississippi River Basin. These carp display negative phonotaxis to broadband sound and thus acoustic deterrents have shown promise for managing their populations. Numerous dams block direct upstream access for the carp; however, fish can bypass these physical obstructions by swimming though navigational locks. Nonphysical acoustic deterrents have the advantage of not effecting navigation, are relatively inexpensive, and could be tuned above the hearing range of non-ostariophysian fishes. Fish also react negatively to high levels of carbon dioxide, and it has been proposed to combine these two stimuli into one deterrent system to reduce potential habituation to long term acoustic playbacks and increase barrier efficacy. Here, the possible synergies of combining these two stimuli into integrated deterrent systems are evaluated.
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    Carbon and Phosphorus Dynamics in Restored Minnesota Peatlands
    (2022-04) Wille, Emilie
    While many peatlands have been drained for anthropogenic purposes across the world, there is currently high interest in restoring peatlands for carbon and nutrient cycling benefits. Peat holds a disproportionate amount of the world’s soil carbon, making peatlands promising ecosystems for mitigating greenhouse gas emissions and climate change. Additionally, peatlands can sequester phosphorus (P) and prevent it from causing eutrophication in downstream waters, but they can also act as a P source under high runoff conditions. This study aimed to investigate the factors impacting 1) peat carbon dioxide (CO2) flux and 2) mobilization of peat P to porewater in a restored bog and fen in Minnesota. Peat CO2 flux was monitored in-situ throughout the growing season in conjunction with peat type, water table depth, and temperature. Peat columns from each site were saturated and subjected to controlled laboratory incubations to relate porewater ortho-P content to temperature and porewater aluminum (Al), calcium (Ca), and iron (Fe) content. A higher water table was significantly related to lower peat CO2 flux in the fen, and peat CO2 flux across both sites was higher in regions with more decomposed peat. During the peak of the growing season, CO2 flux was much higher in the fen than the bog, but both sites had similarly low CO2 flux at the end of the growing season. It is important that restoration ecologists consider a peatland’s water table when restoring a site’s hydrological, ecological, and biogeochemical functioning in order to achieve the greatest carbon benefit. Higher porewater ortho-P corresponded to higher dissolved porewater Al, Ca, and Fe. Additionally, higher initial peat Ca was significantly related to lower porewater P. These ions play a role in binding and mobilizing P, and their dynamics can help researchers predict and mitigate P release and subsequent export.
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    Direct and indirect effects of CO2, nitrogen, and community diversity on plant–enemy interactions
    (Ecological Society of America, 2008) Lau, Jennifer A; Strengbom, Joachim; Stone, Laurie R; Reich, Peter B; Tiffin, Peter
    Resource abundance and plant diversity are two predominant factors hypothesized to influence the amount of damage plants receive from natural enemies. Many impacts of these environmental variables on plant damage are likely indirect and result because both resource availability and diversity can influence plant traits associated with attractiveness to herbivores or susceptibility to pathogens. We used a long-term, manipulative field experiment to investigate how carbon dioxide (CO2) enrichment, nitrogen (N) fertilization, and plant community diversity affect plant traits and the amount of herbivore and pathogen damage experienced by the common prairie legume Lespedeza capitata. We detected little evidence that CO2 or N affected plant traits; however, plants growing in high-diversity treatments (polycultures) were taller, were less pubescent, and produced thinner leaves (higher specific leaf area). Interestingly, we also detected little evidence that CO2 or N affect damage. Plants growing in polycultures compared to monocultures, however, experienced a fivefold increase in damage from generalist herbivores, 64% less damage from specialist herbivores, and 91% less damage from pathogens. Moreover, within diversity treatments, damage by generalist herbivores was negatively correlated with pubescence and often was positively correlated with plant height, while damage by specialist herbivores typically was positively correlated with pubescence and negatively associated with height. These patterns are consistent with changes in plant traits driving differences in herbivory between diversity treatments. In contrast, changes in measured plant traits did not explain the difference in disease incidence between monocultures and polycultures. In summary, our data provide little evidence that CO2 or N supply alter damage from natural enemies. By contrast, plants grown in monocultures experienced greater specialist herbivore and pathogen damage but less generalist herbivore damage than plants grown in diverse communities. Part of this diversity effect was mediated by changes in plant traits, many of which likely are plastic responses to diversity treatments, but some of which may be the result of evolutionary changes in response to these long-term experimental manipulations.
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    Lake Superior inorganic carbon cycling reconstruction 2019-2023
    (2025-04-14) Sandborn, Daniel E; Minor, Elizabeth C; Austin, Jay A; sandb425@umn.edu; Sandborn, Daniel; University of Minnesota Duluth, Large Lakes Observatory
    A gap-filling reconstruction of Lake Superior pCO2 was trained on underway observations utilizing machine learning regression. The output fields in this repository accompany the publication "A neural network-based estimate of the seasonal to inter-annual variability of the Lake Superior carbon cycle" by Sandborn et al. (in review).
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    Species interactions in a changing environment: Elevated CO2 alters the ecological and potential evolutionary consequences of competition
    (Evolutionary Ecology, 2010) Lau, Ja; Shaw, R G; Reich, Peter B; Tiffin, P
    Question: How will global changes impact the ecological and evolutionary outcomes of competition? Hypothesis: Global changes that alter resource availability, such as rising atmospheric carbon dioxide (CO2) concentrations, will alter the effects of competition on mean fitness and patterns of natural selection. Because species exhibit different growth responses to elevated CO2 and because different traits may aid in competition against different taxa. these ecological and evolutionary effects may depend on the Identity of the competitor Organism: Arabidopsis thaliana grown under intraspecific competition or interspecific competition with the C3 grass Biomus inermis or the C4 grass Andropogon gerardu Field site: BioCON (Biodiversity, CO2, and Nitrogen) experiment at Cedar Creek Ecosystem Science Reserve. Minnesota, USA Methods: Manipulate the presence and type of competition experienced by A thaliana populations growing under ambient or elevated CO2 conditions. Measure the interactive effects of CO2 and competition on mean fitness and on patterns of natural selection Conclusions: Elevated CO2 reduces the effects of competition on mean fitness, alters the relative fitness effects of different competition treatments, and minimizes the strength of competition as a selective agent
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    Supporting Data for Ring-Opening Copolymerizations of a CO2-derived δ-Valerolactone with ε-Caprolactone and L-Lactide
    (2024-05-30) Anderson, Ryan A; Fine, Rachel F; Rapagnani, Rachel M; Tonks, Ian A; itonks@umn.edu; Tonks, Ian; University of Minnesota, Tonks group
    These files contain primary data along with associated output from instrumentation supporting all results reported in Anderson et. al. Ring-Opening Copolymerizations of a CO2-derived δ-Valerolactone with ε-Caprolactone and L-Lactide. This work has expanded the synthetic polymer chemistry of the CO2-derived lactone EtVP through ring-opening co-polymerizations with ε-CL and LLA. Polymer properties and microstructures could be tuned through concurrent and se-quential copolymerization strategies, which led to the formation of either block, gradient, or random copolymers. ε-CL block copolymers resulted in semi-crystalline polymers regardless of the molar ratio employed. For LLA, copolymers remained amorphous, and mechanical testing showed improved elasticity relative to PLLA. Furthermore, ε-CL and LLA copolymers could be chemically recycled back to monomer utilizing Sn(Oct)2. While this work lays the foundation for EtVP-based copolymers, investigation into triblocks and other end-of-life options may further improve the potential ap-plications of these CO2-based (co)polymers.
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    Supporting Data for Tunable and Recyclable Polyesters from CO2 and Butadiene
    (2021-10-22) Rapagnani, Rachel M; Dunscomb, Rachel J; Fresh, Alexandra A; Tonks, Ian A; itonks@umn.edu; Tonks, Ian A; University of Minnesota, Department of Chemistry, Tonks group
    These files contain primary data along with associated output from instrumentation supporting all results reported in the referenced manuscript. Findings include: an alternate route to tunable, recyclable polyesters derived from CO2 and butadiene via an intermediary lactone, 3-ethyl-6-vinyltetrahydro-2H-pyran-2-one. Catalytic ring-opening polymerization of the lactone by 1,5,7-triazabicyclo[4.4.0]dec-5-ene yields polyesters with molar masses up to 13.6 kg/mol and pendent vinyl sidechains that can undergo post-polymerization functionalization. The polymer has a low ceiling temperature of 138 ºC, allowing for facile chemical recycling. These results mark the first example of a well-defined polyester derived solely from CO2 and olefins, expanding access to new feedstocks that were once considered unfeasible.