Biogeochemistry Commons^™

Carbonate Chemistry And Carbon Sequestation Driven By Inorganic Carbon Outwelling From Mangroves And Saltmarshes, Gloria M. S. Reithmaier, Alex Cabral, Anirban Akhand, Matthew J. Bogard, Alberto V. Borges, Steven Bouillon, David J. Burdige, Mitchell Call, Nengwang Chen, Xiaogang Chen, Luiz C. Cotovicz Jr., Meagan J. Eagle, Erik Kristensen, Kevin D. Kroeger, Zeyang Lu, Damien T. Maher, J. Lucas Pérez-Lloréns, Raghab Ray, Pierre Taillardat, Joseph J. Tamborski, Rob C. Upstill-Goddard, Faming Wang, Zhaohui Aleck Wang, Kai Xiao, Yvonne Y.Y. Yau, Isaac R. Santos

OES Faculty Publications

Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that >70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing the pH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m^{−2 …}

Beaver Dam Analogs (Bdas) Alter Carbon Pools, Fluxes, And Concentrations Of Intermountain Headwater Streams, Hilary Schultz

Graduate Student Theses, Dissertations, & Professional Papers

Beaver dam analogs (BDAs) have emerged as a climate adaptation and restoration strategy for water resource management in the drought-prone Western U.S., yet the focus has been on their influence on water quantity, overlooking effects on broader ecological components. By increasing water residence time and facilitating sediment retention, BDAs have the potential to influence carbon pools, fluxes, and concentrations. To examine the influence of BDAs on instream and riparian organic C and trace gases, we studied three intermountain headwater streams restored with BDAs two years after restoration during the summer of 2021. We found that there were subtle differences in …

Food Waste Storage Gaseous Emissions Detection And Quantification Using Infrared Spectroscopy, Ryley A. Burton-Tauzer

Cal Poly Humboldt theses and projects

A growing interest in sustainable waste management and the implementation of new policies have prompted a shift towards alternative resource recovery methods for organic waste, including food waste. To effectively assess alternative food waste treatment scenarios, it is important to evaluate the life cycle impacts associated with each scenario. The storage phase of food waste, encompassing its accumulation in kitchens, and storage in bins for collection and transportation, has been overlooked as a source of greenhouse gases in previous studies. This investigation aimed to identify the greenhouse gases emitted during the initial five-day period of low-oxygen storage. An open dynamic …

Controls On Carbon Gas Fluxes From A Temperate Forest Soil, Natalie A. White, Ruth K. Varner, Clarice R. Perryman

Honors Theses and Capstones

Forest soils consume atmospheric methane (CH₄), serving as a major global CH₄ sink that uptake an estimated 22 ± 12 Tg of CH₄ per year. Temperature and soil moisture have been identified as key controls of the microbial consumption of CH₄ in forest soils. Climate-driven warming and changing moisture regimes may impact forest soils’ role in the carbon cycle, and recent works suggests that forests could become weaker CH₄ sinks. Long-term monitoring sites can capture these changes, leading to better predictions of CH₄ exchange between the atmosphere and soils under climate change. This study …

The Variability Of Seawater Carbonate Chemistry In Two Florida Urban Mangrove Ecosystems, Alexandrina R. Rangel

All HCAS Student Capstones, Theses, and Dissertations

Anthropogenic carbon dioxide (CO₂) emissions into the atmosphere are yielding serious impacts across the world’s ocean, including ocean acidification, sea level rise, and increasing seawater temperature. However, these changes are not occurring uniformly across all marine ecosystems. Coastal ecosystems, such as mangroves, already experience extreme and variable environmental conditions due to natural biogeochemical and physical processes. The goal of this study was to document small-scale variability in two urban mangrove ecosystems to gain insight into how ocean acidification will manifest within these systems. Using a stand-up paddleboard, a suite of sensors, and traditional bottle sampling techniques, we measured …

Investigation Of Biogeochemical Mechanisms Of Greenhouse Gas Production In The Urban Hudson River Estuary, Brian Alan Brigham

Dissertations, Theses, and Capstone Projects

Coastal megacities deposit significant amounts of carbon (C), nitrogen (N) and other pollutants into surrounding waters. These inputs, including wastewater and surface water runoff, may affect estuarine and adjacent wetland biogeochemical cycles, microbial production and ultimately greenhouse gas (GHG) efflux. In many megacities pollutant loading is typically greatest after periods of precipitation when the volume of wastewater and storm water runoff exceeds local sanitation capacity, resulting in the discharge of raw sewage into adjacent waters. These combined sewage overflow (CSO) events have received considerable attention primarily due to their potential impact on human health and eutrophication. However, whether these events …

Biogeochemical Cycling In A Headwater Stream And Riparian Zone, A. Capri Gillam

Graduate Theses & Non-Theses

Several teams of researchers at multiple universities are currently measuring annual and seasonal fluxes of carbon dioxide and other greenhouses gases (nitrous oxide and methane) in riparian wetlands and upland forests in the Tenderfoot Creek Experimental Forest (TCEF), a subalpine watershed in the Little Belt Mountains, Montana. In the current thesis, the author characterized the geochemistry and stable carbon isotope composition of shallow groundwater, soil water, and stream water in upper Stringer Creek, near sites that are being investigated for gas chemistry and microbial studies. It was hypothesized that if methanogenesis were a dominant process in the riparian wetlands of …

Carbon Sequestration In Tidal Salt Marshes And Mangrove Ecosystems, Carlos Eduardo Quintana-Alcantara

Master's Projects and Capstones

Wetlands are dynamic systems that provide support to vital environmental functions and services. Wetlands take part in the global carbon cycle by holding organic carbon in biomass, soils and sediments. In recent years, the wetland carbon sequestration capacity has been researched worldwide due to the increase of the concentrations of greenhouse gasses implicated in global warming and climate change. Although coastal wetlands release the greenhouse gasses carbon dioxide, methane and nitrous oxide, these ecosystems maintain high performance in offsetting significant amounts of atmospheric carbon. This paper investigated the carbon sequestration capacity of coastal wetland ecosystems summarizing the environmental conditions and …

Surface Production Fuels Deep Heterotrophic Respiration In Northern Peatlands, J. Elizabeth Corbett, David J. Burdige, Malak M. Tfaily, Angela R. Dial, William T. Cooper, Paul H. Glaser, Jeffrey P. Chanton

OES Faculty Publications

Multiple analyses of dissolved organic carbon (DOC) from pore waters were conducted to define the processes that govern carbon balance in peatlands: (1) source, reactivity, and transport of DOC with respect to vegetation, peat, and age of carbon substrate, (2) reactivity of DOC with respect to molecular size, and (3) lability to photoxidation of surficial DOC. We found that surface organic production fuels heterotrophic respiration at depth in advection-dominated peatlands, especially in fens. Fen DOC was Δ¹⁴Cenriched relative to the surrounding fen peat, and fen respiration products were similar to this enriched DOC indicating that DOC was the …

The Impact Of Decadal Land Cover Change On The Global Warming Potential Of Beringian Arctic Tundra, David Hwei-Len Lin

Open Access Theses & Dissertations

Arctic terrestrial ecosystems play an important role in the global carbon cycle. If arctic warming continues to rise as projected, large amounts of soil carbon stored in these ecosystems could be released to the atmosphere as carbon dioxide or methane and positively enhance greenhouse warming. Thus, improving understanding of the likely future state and fate of arctic soil carbon, and the carbon uptake potential of arctic terrestrial ecosystems are well recognized research priorities.

At the pan-arctic scale, decadal increases in NDVI (Normalized Difference Vegetation Index), an index of vegetation productivity, have been observed from satellite imagery, indicating a general greening …

Landscape-Level Controls On Dissolved Carbon Flux From Diverse Catchments Of The Circumboreal, Suzanne E. Tank, Karen E. Frey, Robert G. Striegl, Peter A. Raymond, Robert M. Holmes, James W. Mcclelland, Bruce J. Peterson

Geography

While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3-) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO 3-. We explored landscape-level controls on DOC and HCO3- flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on riverine dissolved C flux. To do this, we undertook a multivariate analysis that partitioned the variance attributable to known, key regulators of dissolved C flux (runoff, lithology, and vegetation) prior to examining the effect of permafrost, …

Co2 Sensitivity Of Southern Ocean Phytoplankton, Philippe D. Tortell, Christopher D. Payne, Yingyu Li, Scarlett Trimborn, Bjorn Rost, Walker O. Smith, Christina Riesselman, Robert B. Dunbar, Peter Sedwick, Giacomo R. Ditullio

OES Faculty Publications

The Southern Ocean exerts a strong impact on marine biogeochemical cycles and global air-sea CO₂ fluxes. Over the coming century, large increases in surface ocean CO₂ levels, combined with increased upper water column temps. and stratification, are expected to diminish Southern Ocean CO₂ uptake. These effects could be significantly modulated by concomitant CO₂-dependent changes in the region's biol. carbon pump. Here we show that CO₂ concentrations affect the physiology, growth and species composition. of phytoplankton assemblages in the Ross Sea, Antarctica. Field results from in situ sampling and ship-board incubation experiments demonstrate that inorganic …

Interactions Between Changing Pco2, N2 Fixation, And Fe Limitation In The Marine Unicellular Cyanobacterium Crocosphaera, Fei-Xue Fu, Margaret R. Mulholland, Nathan S. Garcia, Aaron Beck, Mark E. Warner, Sergio A. Sañudo, David A. Hutchins

OES Faculty Publications

We examined the physiological responses of steady-state iron (Fe)-replete and Fe-limited cultures of the biogeochemically critical marine unicellular diazotrophic cyanobacterium Crocosphaera at glacial (19 Pa; 190 ppm), current (39 Pa; 380 ppm), and projected year 2100 (76 Pa; 750 ppm) CO₂ levels. Rates of N₂ and CO₂ fixation and growth increased in step with increasing partial pressure of CO₂ (pCO₂), but only under Fe- replete conditions. N₂) and carbon fixation rates at 75 Pa CO₂ were 1.4-1.8-fold and 1.2-2.0-fold higher, respectively, relative to those at present day and glacial pCO_{2 …}

Iron In East Antarctic Snow: Implications For Atmospheric Iron Deposition And Algal Production In Antarctic Waters, Ross Edwards, Peter N. Sedwick

OES Faculty Publications

To evaluate the deposition and solubility of aerosol iron in the Antarctic seasonal sea ice zone (SSIZ), iron was measured in snow samples collected from three areas in the SSIZ (Prydz Bay, Dumont d'Urville Sea and Ross Sea) and one continental area (Princess Elizabeth Land) of East Antarctica. Concentrations of total-dissolvable iron (that soluble at pH ~2) ranged from 20-2950 pg g^-1, with the lowest concentrations measured in snow from the Dumont d'Urville Sea. Using estimates of snow accumulation rates, we calculate atmospheric iron deposition fluxes of 0.017-0.11 mg m^-2 yr^-1(0.30-2.0 μmol m^-2 yr …

Data Report: Carbon Isotopic Composition Of Dissolved Co2, Co2 Gas, And Methane, Blake-Bahama Ridge And Northeast Bermuda Rise, Odp Leg 172, Walter S. Borowski, Namik Cagatay, Y Tournois, Charles K. Paull

EKU Faculty and Staff Scholarship

Carbon isotopic data of interstitial dissolved CO2 (ΣCO2), CO2 gas, and methane show that a variety of microbial diagenetic processes produce the observed isotopic trends. Anaerobic methane oxidation (AMO) is an important process near the sulfate-methane interface (SMI) that strongly influences the isotopic composition of ΣCO2 in the sulfate reduction and upper methanogenic zones, which in turn impacts methane isotopic composition. Dissolved CO2 and methane are maximally depleted in 3C near the SMI, where C values are as light as –31.8‰ and –101‰ PDB for ΣCO2 and methane, respectively. CO2 reduction links the CO2 and methane pools in the methanogenic …