Biological Sequestration Research Articles

Enhanced algal CO 2 sequestration through calcite deposition by Chlorella sp. and Spirulina platensis in a mini-raceway pond

Biological CO 2 sequestration using algal reactors is one of the most promising and environmentally benign technologies to sequester CO 2. This research study was taken up to alleviate certain limitations associated with the technology such as low CO 2 sequestration efficiency and low biomass yields. The study demonstrates an increase in CO 2 sequestration efficiency by maneuvering chemically aided biological sequestration of CO 2. Chlorella sp. and Spirulina platensis showed 46% and 39% mean fixation efficiency, respectively, at input CO 2 concentration of 10%. The effect of acetazolamide, a potent carbonic anhydrase inhibitor, on CO 2 sequestration efficiency was studied to demonstrate the role of carbonic anhydrase in calcite deposition. Calcite formed by both species was characterized by scanning electron microscopy coupled electron dispersive spectroscopy and X-ray diffraction. The overall scheme of calcite deposition coupled CO 2 fixation with commercially utilizable biomass as a product seems a viable option in the efforts to sequester increasing CO 2 emissions.

The cost of carbon abatement through community forest management in Nepal Himalaya

This paper estimates the economic returns to carbon abatement through biological sequestration in community managed forest under future REDD policy, and compares these for three possible management scenarios. For the estimation, the research relies on forest inventory data together with other socio-economic and resources use data collected from forest users in three sites of Nepal Himalaya. The paper estimates the incremental carbon from forest enhancement on a yearly basis over a five-year period using the value of $ 1 and $ 5 per tCO2 for conservative analysis. The results based on the three sites indicate that community forest management may be one of the least cost ways to abate carbon with a break-even price under Scenario 2 which ranges from $ 0.55 to $ 3.70 per tCO2. However, bringing community forests into the carbon market may entail high opportunity costs as forests provide numerous non-monetary benefits to the local population, who regard these as the main incentive for conservation and management. An important finding of the research is that if forest resources use by local communities is not permitted, then carbon trading will not be attractive to them as revenue from carbon will not cover the cost foregone by not harvesting forest resources.

Bio-sequestration of carbon dioxide using carbonic anhydrase enzyme purified from Citrobacter freundii

The increase in the atmospheric concentrations of one of the vital green house gasses, carbon dioxide, due to anthropogenic interventions has led to several undesirable consequences such as global warming and related changes. In the global effort to combat the predicted disaster, several CO2 capture and storage technologies are being deliberated. One of the most promising biological carbon dioxide sequestration technologies is the enzyme catalyzed carbon dioxide sequestration into bicarbonates which was endeavored in this study with a purified C. freundii SW3 β-carbonic anhydrase (CA). An extensive screening process for biological sequestration using CA has been defined. Six bacteria with high CA activity were screened out of 102 colonies based on plate assay and presence of CA in these bacteria was further emphasized by activity staining and Western blot. The identity of selected bacteria was confirmed by 16S rDNA analysis. CA was purified to homogeneity from C. freundii SW3 by subsequent gel filtration and ion exchange chromatography which resulted in a 24 kDa polypeptide and this is in accordance with the Western blot results. The effect of host on metal ions, cations and anions which influence activity of the enzyme in sequestration studies suggests that mercury and HCO3 − ion almost completely inhibit the enzyme whereas sulfate ion and zinc enhances carbonic anhydrase activity. Calcium carbonate deposition was observed in calcium chloride solution saturated with carbon dioxide catalyzed by purified enzyme and whereas a sharp decrease in calcium carbonate formation has been noted in purified enzyme samples inhibited by EDTA and acetazolamide.

Oxygen minimum zones (OMZs) in the modern ocean

In the modern ocean, oxygen minimum zones (OMZs) are potential traces of a primitive ocean in which Archean bacteria lived and reduced chemical anomalies occurred. But OMZs are also keys to understanding the present unbalanced nitrogen cycle and the oceans’ role on atmospheric greenhouse control. OMZs are the main areas of nitrogen loss (as N 2, N 2O) to the atmosphere through denitrification and anammox, and could even indirectly mitigate the oceanic biological sequestration of CO 2. It was recently hypothesized that OMZs are going to spread in the coming decades as a consequence of global climate change. Despite an important OMZ role for the origin of marine life and for the biogeochemical cycles of carbon and nitrogen, there are some key questions on the structure of OMZs at a global scale. There is no agreement concerning the threshold in oxygen that defines an OMZ, and the extent of an OMZ is often evaluated by denitrification criteria which, at the same time, are O 2-dependent. Our work deals with the identification of each OMZ, the evaluation of its extent, volume and vertical structure, the determination of its seasonality or permanence and the comparison between OMZs and denitrification zones at a global scale. The co-existence in the OMZ of oxic (in its boundaries) and suboxic (even anoxic, in its core) conditions involves rather complex biogeochemical processes such as strong remineralization of the organic matter, removal of nitrate and release of nitrite. The quantitative OMZ analysis is focused on taking into account the whole water volume under the influence of an OMZ and adapted to the study of the specific low oxygen biogeochemical processes. A characterization of the entire structure for the main and most intense OMZs (O 2 < 20 μM reaching 1 μM in the core) is proposed based on a previously published CRIO criterion from the eastern South Pacific OMZ and including a large range of O 2 concentrations. Using the updated global WOA2005 O 2 climatology, the four known tropical OMZs in the open ocean have been described: the Eastern South Pacific and Eastern Tropical North Pacific, in the Pacific Ocean; the Arabian Sea and Bay of Bengal, in the Indian Ocean. Moreover, the Eastern Sub-Tropical North Pacific (25–52°N) has been identified as a lesser known permanent deep OMZ. Two additional seasonal OMZs at high latitude have also been identified: the West Bering Sea and the Gulf of Alaska. The total surface of the permanent OMZs is 30.4 millions of km 2 (∼8% of the total oceanic area), and the volume of the OMZ cores (10.3 millions of km 3) corresponds to a value ∼7 times higher than previous evaluations. The volume of the OMZ cores is about three times larger than that of the associated denitrification zone, here defined as NMZ (‘nitrate deficit or NDEF > 10 μM’ maximum zone). The larger OMZ, relative to the extent of denitrification zone, suggests that the unbalanced nitrogen cycle on the global scale could be more intense than previously recognized and that evaluation of the OMZ from denitrification could underestimate their extent.

Photochemical Mineralization of Europium, Titanium, and Iron Oxyhydroxide Nanoparticles in the Ferritin Protein Cage

The Fe storage protein ferritin was used as a size-constrained reaction vessel for the photoreduction and reoxidation of complexed Eu, Fe, and Ti precursors for the formation of oxyhydroxide nanoparticles. The resultant materials were characterized by dynamic light scattering, gel electrophoresis, UV-vis spectroscopy, and transmission electron microscopy. The photoreduction and reoxidation process is inspired by biological sequestration mechanisms observed in some marine siderophore systems.

Forestry and the carbon market response to stabilize climate

This paper investigates the potential contribution of forestry management in meeting a CO 2 stabilization policy of 550 ppmv by 2100. In order to assess the optimal response of the carbon market to forest sequestration, we couple two global models. An energy–economy–climate model for the study of climate policies is linked with a detailed forestry model through an iterative procedure to provide the optimal abatement strategy. Results show that forestry is a determinant abatement option and could lead to significantly lower policy costs if included. Linking forestry management to the carbon market has the potential to alleviate the policy burden of 50 ppmv or equivalently of 1 4 ∘ C , and to significantly decrease the price of carbon. Biological sequestration will mostly come from avoided deforestation in tropical-forest-rich countries. The inclusion of this mitigation option is demonstrated to crowd out some of the traditional abatement in the energy sector and to lessen induced technological change in clean technologies.

Forestry and the Carbon Market Response to Stabilize Climate

This paper investigates the potential contribution of forestry management in meeting a CO2 stabilization policy of 550 ppmv by 2100. In order to assess the optimal response of the carbon market to forest sequestration we couple two global models. An energy-economy-climate model for the study of climate policies is linked with a detailed forestry model through an iterative procedure to provide the optimal abatement strategy. Results show that forestry is a determinant abatement option and could lead to significantly lower policy costs if included. Linking forestry management to the carbon market has the potential to delay the policy burden, and is expected to reduce the price of carbon of 40% by 2050. Biological sequestration will mostly come from avoided deforestation in tropical forests rich countries. The inclusion of this mitigation option is demonstrated to crowd out some of the traditional abatement in the energy sector and to lessen induced technological change in clean technologies.

Forestry and the Carbon Market Response to Stabilize Climate

This paper investigates the potential contribution of forestry management in meeting a CO2 stabilization policy of 550 ppmv by 2100. In order to assess the optimal response of the carbon market to forest sequestration we couple two global models. An energy-economy-climate model for the study of climate policies is linked with a detailed forestry model through an iterative procedure to provide the optimal abatement strategy. Results show that forestry is a determinant abatement option and could lead to significantly lower policy costs if included. Linking forestry management to the carbon market has the potential to delay the policy burden, and is expected to reduce the price of carbon of 40% by 2050. Biological sequestration will mostly come from avoided deforestation in tropical forests rich countries. The inclusion of this mitigation option is demonstrated to crowd out some of the traditional abatement in the energy sector and to lessen induced technological change in clean technologies.

Investigating the Application of Enzyme Carbonic Anhydrase for CO2 Sequestration Purposes

Biological sequestration of carbon dioxide (CO2) in geological formations is one of the proposed methods to reduce the carbon dioxide released into the atmosphere. In this method, an enzyme is used to enhance the hydration and subsequent precipitation of CO2. In the present work, the effect of bovine carbonic anhydrase on the hydration of CO2, and its precipitation in the form of calcium carbonate, was studied. The enzyme enhanced the hydration reaction. The rate of hydration reaction increased with both the enzyme concentration and temperature. The precipitation of calcium carbonate was promoted in the presence of the enzyme. The concentration of the enzyme did not affect the precipitation; however, temperature impacted the precipitation of calcium carbonate. At higher temperatures, less calcium carbonate was formed. Also, in the presence of the enzyme, calcium carbonate settled more quickly. The enzyme activity was not influenced by the pH of the reaction mixture. In contrast, the formation of calcium c...

Curbing the U.S. carbon deficit

The U.S. emitted approximately 1.58 petagrams (Pg) of fossil fuel carbon in 2001, approximately one-quarter of global CO(2) production. With climate change increasingly likely, strategies to reduce carbon emissions and stabilize climate are needed, including greater energy efficiency, renewable energy sources, geoengineering, decarbonization, and geological and biological sequestration. Two of the most commonly proposed biological strategies are restoring organic carbon in agricultural soils and using plantations to sequester carbon in soils and wood. Here, we compare scenarios of land-based sequestration to emissions reductions arising from increased fuel efficiency in transportation, targeting ways to reduce net U.S. emissions by 10% ( approximately 0.16 Pg of carbon per year). Based on mean sequestration rates, converting all U.S. croplands to no-till agriculture or retiring them completely could sequester approximately 0.059 Pg of carbon per year for several decades. Summary data across a range of plantations reveal an average rate of carbon storage an order of magnitude larger than in agricultural soils; in consequence, one-third of U.S. croplands or 44 million hectares would be needed for plantations to reach the target of approximately 0.16 Pg of carbon per year. For fossil fuel reductions, cars and light trucks generated approximately 0.31 Pg of carbon in U.S. emissions in 2001. To reduce net emissions by 0.16 Pg of carbon per year, a doubling of fuel efficiency for cars and light trucks is needed, a change feasible with current technology. Issues of permanence, leakage, and economic potentials are discussed briefly, as is the recognition that such scenarios are only a first step in addressing total U.S. emissions.

Review - Roger A. Sedjo (2003): Economics of Forestry

Review - Roger A. Sedjo (2003): Economics of Forestry

ROLE OF TERRESTRIAL SEQUESTRATION IN MEETING KYOTO TARGETS

There is strong scientific consensus that the concentration of greenhouse gases in the atmosphere is increasing due to human activities and that this is leading to changes in the Earth’s climate. Fluxes between terrestrial ecosystems and the atmosphere are a significant component of the global carbon cycle and actions to increase net storage in terrestrial ecosystems (often called sinks) will delay the build up of greenhouse gases in the atmosphere. There is still political debate as to which sinks may be accounted in compliance with the Kyoto Protocol. The decisions made will affect the total costs of compliance with the Kyoto Protocol by a factor or two to four. Geological sequestration may also reduce emissions by an amount of the same order as sequestration in terrestrial sinks. Biological and geological sequestration offer a significant opportunity to buy several decades of time to make an efficient transition to technologies and economies that release less greenhouse gasses to the atmosphere from energy production and industrial processes.

Phosphate Depletion in the Western North Atlantic Ocean

Surface waters of the subtropical Sargasso Sea contain dissolved inorganic phosphate (DIP) concentrations of 0.2 to 1.0 nanomolar, which are sufficiently low to result in phosphorus control of primary production. The DIP concentrations in this area (which receives high inputs of iron-rich dust from arid regions of North Africa) are one to two orders of magnitude lower than surface levels in the North Pacific (where eolian iron inputs are much lower and water column denitrification is much more substantial). These data indicate a severe relative phosphorus depletion in the Atlantic. We hypothesize that nitrogen versus phosphorus limitation of primary production in the present-day ocean may be closely linked to iron supply through control of dinitrogen (N2) fixation, an iron-intensive metabolic process. Although the oceanic phosphorus inventory may set the upper limit for the total amount of organic matter produced in the ocean over geological time scales, at any instant in geological time, oceanic primary production may fall below this limit because of a persistent insufficient iron supply. By controlling N2 fixation, iron may control not only nitrogen versus phosphorus limitation but also carbon fixation and export stoichiometry and hence biological sequestration of atmospheric carbon dioxide.

Evolution of the nitrogen cycle and its influence on the biological sequestration of CO2 in the ocean

Over geological time, photosynthetic carbon fixation in the oceans has exceeded respiratory oxidation of organic carbon. The imbalance between the two processes has resulted in the simultaneous accumulation of oxygen in, and drawdown of carbon dioxide from, the Earth's atmosphere, and the burial of organic carbon in marine sediments1–3. It is generally assumed that these processes are limited by the availability of phosphorus4,5, which is supplied by continental weathering and fluvial discharge5–7. Over the past two million years, decreases in atmospheric carbon dioxide concentrations during glacial periods correlate with increases in the export of organic carbon from surface waters to the marine sediments8–11, but variations in phosphorus fluxes appear to have been too small to account for these changes12,13. Consequently, it has been assumed that total oceanic primary productivity remained relatively constant during glacial-to-interglacial transitions, although the fraction of this productivity exported to the sediments somehow increased during glacial periods12,14. Here I present an analysis of the evolution of biogeochemical cycles which suggests that fixed nitrogen, not phosphorus, limits primary productivity on geological timescales. Small variations in the ratio of nitrogen fixation to denitrification can significantly change atmospheric carbon dioxide concentrations on glacial-to-interglacial timescales. The ratio of these two processes appears to be determined by the oxidation state of the ocean and the supply of trace elements, especially iron.

Role of the marine biosphere in the global carbon cycle

The geochemical disequilibrium of our planet is due mainly to carbon sequestration by marine organisms over geological time. Changes in atmospheric CO, during interglacial-glacial transitions require biological sequestration of carbon in the oceans. Nutrient-limited export flux from new production in surface waters is the key process in this sequestration. The most common model for export flux ignores potentially important nutrient sources and export mechanisms. Export flux occurs as a result of biological processes whose complexity appears not to bc accommodated by the principal classes of simulation models, this being especially true for food webs dominated by single-celled protists whose trophic function is more dispersed than among the multicelled metazoa. The fashionable question concerning a hypothetical “missing sink” for CO2 emissions is unanswerable because of imprecision in our knowledge of critical flux rates. This question also diverts attention from more relevant studies of how the biological pump may be perturbed by climatic consequences of CO, emissions. Under available scenarios for climate change, such responses may seem more likely to reinforce, rather than mitigate, the rate of increase of atmospheric CO,.