Site For Sequestration Research Articles

Sub-seafloor Carbon Dioxide Storage Potential on the Juan de Fuca Plate, Western North America

The Juan de Fuca plate, off the western coast of North America, has been suggested as a site for geological sequestration of anthropogenic carbon dioxide because of its many attractive characteristics (high permeability, large storage capacity, reactive rock types). Here we model CO2 injection into fractured basalts comprising the upper several hundred meters of the sub-seafloor basalt reservoir, overlain with low-permeability sediments and a thick saline water column, to examine the feasibility of this reservoir for CO2 storage. Our simulations indicate that the sub-seafloor basalts of the Juan de Fuca plate may be an excellent CO2 storage candidate, as multiple trapping mechanisms (hydrodynamic, density inversions, and mineralization) act to keep the CO2 isolated from terrestrial environments. Questions remain about the lateral extent and connectivity of the high permeability basalts; however, the lack of wells or boreholes and thick sediment cover maximize storage potential while minimizing potential leakage pathways. Although promising, more study is needed to determine the economic and sociological viability of this option.

Application of simplified models to CO2 migration and immobilization in large-scale geological systems

Long-term stabilization of injected carbon dioxide (CO2) is an essential component of risk management for geological carbon sequestration operations. However, migration and trapping phenomena are inherently complex, involving processes that act over multiple spatial and temporal scales. One example involves centimeter-scale density instabilities in the dissolved CO2 region leading to large-scale convective mixing that can be a significant driver for CO2 dissolution. Another example is the potentially important effect of capillary forces, in addition to buoyancy and viscous forces, on the evolution of mobile CO2. Local capillary effects lead to a capillary transition zone, or capillary fringe, where both fluids are present in the mobile state. This small-scale effect may have a significant impact on large-scale plume migration as well as long-term residual and dissolution trapping. Computational models that can capture both large and small-scale effects are essential to predict the role of these processes on the long-term storage security of CO2 sequestration operations. Conventional modeling tools are unable to resolve sufficiently all of these relevant processes when modeling CO2 migration in large-scale geological systems. Herein, we present a vertically-integrated approach to CO2 modeling that employs upscaled representations of these subgrid processes. We apply the model to the Johansen formation, a prospective site for sequestration of Norwegian CO2 emissions, and explore the sensitivity of CO2 migration and trapping to subscale physics. Model results show the relative importance of different physical processes in large-scale simulations. The ability of models such as this to capture the relevant physical processes at large spatial and temporal scales is important for prediction and analysis of CO2 storage sites.

Giant Fornix Syndrome

To describe the demographics, characteristics, and treatment of giant fornix syndrome, a rare cause of chronic purulent conjunctivitis in the elderly. Retrospective chart review of five patients with giant fornix syndrome evaluated by the Cornea Service, Oculoplastics and Orbital Surgery Service and the Department of Pathology at the Wills Eye Institute. The median age of the 5 female patients was 75 years (mean 80, range 70-95). The median duration of eye symptoms before presentation was 2 years (mean 2.4, range 1-4). Before referral, the chronic conjunctivitis was treated with topical antibiotics in all 5 cases and with additional dacryocystorhinostomy in one case. The right eye was affected in 2 cases, and the left eye was affected in the other 3 cases. Floppy eyelids were present in 2 cases. The superior fornix was involved in 4 cases, and the inferior fornix was involved in one case. Pseudomembranes and superficial punctate keratitis (SPK) were seen in 3 cases. Diagnosis of giant fornix syndrome was made in all 5 cases. Conjunctival culture grew methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and S. aureus in singular cases. Case 1 was treated with topical moxifloxacin, Case 2 was treated with topical vancomycin and repair of the upper eyelid, Case 3 was treated with topical besifloxacin, and Case 4 was treated with dacryocystorhinostomy and topical vancomycin. Case 5 was treated with reconstruction of the left upper eyelid. The median duration of follow up was 4 months (mean 21.6, range 1-84). Giant fornix syndrome can lead to chronic relapsing conjunctivitis in the elderly. Deep conjunctival fornices in affected patients can be a site for prolonged sequestration of bacteria causing recurrent infections. Removing the infected debris from the superior fornix and reconstruction of the upper eyelid may prevent the recurrent chronic persistent infection.

The Effect of Indole and Similar Compounds on Yvc1P and Vacuolar Calcium Release in Saccharomyces Cerevisiae

Transient Receptor Potential (TRP) channels act as environmental sensors in eukaryotic cells. TRP channels frequently respond to more than one signal, yet the mechanism of this integration is poorly understood.The S. cerevisiae genome contains a single TRP channel gene, encoding the 78 kDa vacuolar protein Yvc1p. The vacuole serves as the primary site for calcium sequestration in Saccharomyces cerevisiae. Calcium ions are released from the vacuole into the cytosol through TRP channel homologue, Yvc1p. Yvc1p is known to be activated directly by both hyperosmotic shock1 and cytoplasmic Ca2+2, and recently John Haynes et al have shown that activation by hyperosmotic can be enhanced by indole and related compounds3.In this study, we detail the effects of indole-related compounds in modulating the activity of Yvc1p in vivo through a luminescence assay_aequorin is utilized as a reporter of cytoplasmic calcium concentration. Like John Haynes et al, we find these compounds augment hyperosmotic shock-induced Yvc1p activity. Further, we find that several compounds may work to directly enhance Yvc1p activity, independent of hyperosmotic shock. The compounds act in a concentration and species dependent manner, and have no effect in a delta Yvc1 strain, indicating that they mediate their response through Yvc1p.1Zhou XL et al (2003) Proc Natl Acad Sci U S A 100: 7105-7110.2Bertl A, Slayman CL (1990) Proc Natl Acad Sci U S A 87: 7824-7828.3John Haynes W. et al (2008) FEBS Letters. 582: 1514.

A drawdown solution for constant-flux pumping in a confined anticline aquifer

An anticline, known as a convex-upward fold in layers of rock, commonly is formed during lateral compression, which may be elected as a potential site for carbon sequestration. A mathematical model is developed in this study for describing the steady-state drawdown distribution in an anticline aquifer in response to the constant-flux pumping. The topographical shape of the anticline is mimicked by three successive blocks. The solution is obtained by applying the infinite Fourier transform and the finite Fourier cosine transform in each blocks and acquiring the hydraulic continuities between the blocks. Simulated results reveal that the introduction of a thin-limbs or narrow-ridged anticline would produce a much greater head drop in the ridge zone. For a well of constant pumping rate, the dimensionless drawdown around the well increases with decreasing well screen length or/and aquifer anisotropy ratio. An examination of the effect of well location on the drawdown reveals that the partially penetrating well located at the top-middle of the ridge zone produces the largest drawdown. The simulation of the flow in an anticline aquifer based on MODFLOW results in slightly smaller drawdown values in most regions when compared with those predicted by the present solution. The present solution can also be used to simulate the flow in a slab-shaped aquifer or a hillslope aquifer. It can be applied to determine the aquifer parameters if coupled with an optimization scheme and to provide the basis for selecting a potential site for carbon sequestration in the future as well.

Spontaneous Postpartum Clearance of Plasmodium falciparum Parasitemia in Pregnant Women, Benin

The question of malaria in the postpartum period is controversial. Malaria was investigated during a randomized trial of intermittent preventive treatment in pregnancy in Benin. Women infected at delivery were tested for parasitemia in the early postpartum period; they had not received treatment unless they were symptomatic. Among the 35 of 1,346 infected women, parasitologic follow-up results could not be interpreted in 15 because they were treated for symptoms, 18 cleared parasitemia spontaneously within five days postpartum, and 2 had a strong decrease in parasitemia before being treated. Because the placenta is the privileged site for sequestration of parasites, it facilitates their persistence during pregnancy, and its elimination may rapidly induce their clearance.

Characteristics of CO2 sequestration in saline aquifers

Storage of CO2 in saline aquifers is a viable option for reducing the amount of CO2 released to the atmosphere. This paper provides an overall review of CO2 sequestration in saline aquifers. First, the principles of CO2 sequestration are presented, including CO2 phase behavior, CO2-water-rock interaction, and CO2 trapping mechanisms. Then storage capacity and CO2 injectivity are discussed as the main determinants of the storage potential of saline aquifers. Next, a site section process is addressed considering basin characteristics, reservoir characteristics, and economic and social concerns. Three main procedures are then presented to investigate the suitability of a site for CO2 sequestration, including site screening, detailed site characterization, and pilot field-scale test. The methods for these procedures are also presented, such as traditional site characterization methods, laboratory experiments, and numerical simulation. Finally, some operational aspects of sequestration are discussed, including well type, injection rate, CO2 purity, and injection strategy.

The impact of CO2 on shallow groundwater chemistry: observations at a natural analog site and implications for carbon sequestration

In a natural analog study of risks associated with carbon sequestration, impacts of CO2 on shallow groundwater quality have been measured in a sandstone aquifer in New Mexico, USA. Despite relatively high levels of dissolved CO2, originating from depth and producing geysering at one well, pH depression and consequent trace element mobility are relatively minor effects due to the buffering capacity of the aquifer. However, local contamination due to influx of brackish waters in a subset of wells is significant. Geochemical modeling of major ion concentrations suggests that high alkalinity and carbonate mineral dissolution buffers pH changes due to CO2 influx. Analysis of trends in dissolved trace elements, chloride, and CO2 reveal no evidence of in situ trace element mobilization. There is clear evidence, however, that As, U, and Pb are locally co-transported into the aquifer with CO2-rich brackish water. This study illustrates the role that local geochemical conditions will play in determining the effectiveness of monitoring strategies for CO2 leakage. For example, if buffering is significant, pH monitoring may not effectively detect CO2 leakage. This study also highlights potential complications that CO2 carrier fluids, such as brackish waters, pose in monitoring impacts of geologic sequestration.

Assessing risk to fresh water resources from long term CO2 injection–laboratory and field studies

Abstract In developing a site for geologic sequestration, one must assess potential consequences of failure to adequately contain injected carbon dioxide (CO2). Upward migration of CO2 or displacement of saline water because of increased pressure might impact protected water resources 100s to 1000s of meters above a sequestration interval. Questions posed are: (1) Can changes in chemistry of fresh water aquifers provide evidence of CO2 leakage from deep injection/sequestration reservoirs containing brine and or hydrocarbons? (2) What parameters can we use to assess potential impacts to water quality? (3) If CO2 leakage to freshwater aquifers occurs, will groundwater quality be degraded and if so, over what time period? Modeling and reaction experiments plus known occurrences of naturally CO2-charged potable water show that the common chemical reaction products from dissolution of CO2 into freshwater include rapid buffering of acidity by dissolution of calcite and slower equilibrium by reaction with clays and feldspars. Results from a series of laboratory batch reactions of CO2 with diverse aquifer rocks show geochemical response within hours to days after introduction of CO2. Results included decreased pH and increased concentrations of cations in CO2 experimental runs relative to control runs using argon (Ar). Some cation (Ba, Ca, Fe, Mg, Mn, and Sr) concentrations increased over and an order of magnitude during CO2 runs. Results are aquifer dependant in that experimental vessels containing different aquifer rocks showed different magnitudes of increase in cation concentrations. Field studies designed to improve understanding of risk to fresh water are underway in the vicinity of (1) SACROC oilfield in Scurry County, Texas, USA where CO2 has been injected for enhanced oil recovery (EOR) since 1972 and (2) the Cranfield unit in Adams County, Mississippi, USA where CO2 EOR is currently underway. Both field studies are funded by the U.S. Department of Energy (DOE) regional carbon sequestration partnership programs and industrial sponsors. Preliminary results of groundwater monitoring are currently available for the SACROC field study where researchers investigated 68 water wells and one spring during five field excursions between June 2006 and July 2008. Results to date show no trend of preferential degradation below drinking water standards in areas of CO2 injection (inside SACROC) as compared to areas outside of the SACROC oil field.

Effects of arbuscular mycorrhiza and phosphorus application on artemisinin concentration in Artemisia annua L.

Annual wormwood (Artemisia annua L.) produces an array of complex terpenoids including artemisinin, a compound of current interest in the treatment of drug-resistant malaria. However, this promising antimalarial compound remains expensive and is hardly available on the global scale. Synthesis of artemisinin has not been proved to be feasible commercially. Therefore, increase in yield of naturally occurring artemisinin is an important area of investigation. The effects of inoculation by two arbuscular mycorrhizal (AM) fungi, Glomus macrocarpum and Glomus fasciculatum, either alone or supplemented with P-fertilizer, on artemisinin concentration in A. annua were studied. The concentration of artemisinin was determined by reverse-phase high-performance liquid chromatography with UV detection. The two fungi significantly increased concentration of artemisinin in the herb. Although there was significant increase in concentration of artemisinin in nonmycorrhizal P-fertilized plants as compared to control, the extent of the increase was less compared to mycorrhizal plants grown with or without P-fertilization. This suggests that the increase in artemisinin concentration may not be entirely attributed to enhanced P-nutrition and improved growth. A strong positive linear correlation was observed between glandular trichome density on leaves and artemisinin concentration. Mycorrhizal plants possessed higher foliar glandular trichome (site for artemisinin biosynthesis and sequestration) density compared to nonmycorrhizal plants. Glandular trichome density was not influenced by P-fertilizer application. The study suggests a potential role of AM fungi in improving the concentration of artemisinin in A. annua.

Fidelity and spatio-temporal control in MAP kinase (ERKs) signalling.

The mitogen activated protein (MAP) kinase module: (Raf -->MEK-->ERKs) is central to the control of cell growth, cell differentiation and cell survival. The fidelity of signalling and the spatio-temporal activation are key determinants in generating precise biological responses. The fidelity is ensured by scaffold proteins - protein kinase 'insulators' - and by specific docking sites. The duration and the intensity of the response are in part controlled by the compartmentalization of the signalling molecules. Growth factors promote rapid nuclear translocation and persistent activation of p42/p44 MAP kinases, respectively and ERK2/ERK1, during the entire G1 period with an extinction during the S-phase. These features are exquisitely controlled by the temporal induction of the MAP kinase phosphatases, MKP1-3. MKP1 and 2 induction is strictly controlled by the activation of the MAP kinase module providing evidence for an auto-regulatory mechanism. This negative regulatory loop is further enhanced by the capacity of p42/p44 MAPK to phosphorylate MKP1 and 2. This action reduces the degradation rate of MKPs through the ubiquitin-proteasomal system. Whereas the two upstream kinases of the module (Raf and MEK) remain cytoplasmic, ERKs (anchored to MEK in the cytoplasm of resting cells) rapidly translocate to the nucleus upon mitogenic stimulation. This latter process is rapid, reversible and controlled by the strict activation of the MAPK cascade. Following long-term MAPK stimulation, p42/p44 MAPKs progressively accumulate in the nucleus in an inactive form. Therefore we propose that the nucleus represents a site for ERK action, sequestration and signal termination. With the generation of knockdown mice for each of the ERK isoforms, we will illustrate that besides controlling cell proliferation the ERK cascade also controls cell differentiation and cell behaviour.

Fidelity and spatio-temporal control in MAP kinase (ERKs) signalling

Extracellular signals transduced via receptor tyrosine kinases, G-protein-coupled receptors or integrins activate Ras, a key switch in cellular signalling. Although Ras can activate multiple downstream effectors (PI3K, Ral…) one of the major activated pathway is a conserved sequential protein kinase cascade referred to as the mitogen activated protein (MAP) kinase module: Raf>MEK>ERK. The fidelity of signalling among protein kinases and the spatio-temporal activation are certainly key determinants for generating precise biological responses. The fidelity is ensured by scaffold proteins, a sort of protein kinase “insulators” and/or specific docking sites among the members of the signalling cascade. These docking sites are found in upstream and downstream regulators and MAPK substrates [Nat Cell Biol 2 2000 110]. The duration and the intensity of the response are in part controlled by the compartmentalisation of the signalling molecules. Growth factors promote nuclear accumulation and persistent activation of ERK (p42/p44 MAP kinases) during the entire G1 period with an extinction during S-phase. These features are exquisitely well controlled by (i) the temporal induction of the MAP kinase phosphatases, MKP1-3, and (ii) the compartmentalisation of the signalling molecules. We have shown that MKP1-2 induction is strictly controlled by the activation of the MAP kinase module providing evidence for an autoregulatory mechanism. This negative regulatory loop was further enhanced by the capacity of ERK to phosphorylate MKP1 and 2. This action reduced the degradation rate of these MKPs through the ubiquitin–proteasomal system [Science 286 1999 2514].Whereas the two upstream kinases of the module, Raf and MEK remained cytoplasmic, ERK anchored to MEK in the cytoplasm of resting cells, rapidly translocated to the nucleus upon mitogenic stimulation. This process was rapid, reversible, and controlled by the strict activation of the MAPK cascade. Prevention of this nuclear translocation, by overexpression of a cytoplasmic ERK-docking molecule (inactive MKP3) prevented growth factor-stimulated DNA replication [EMBO J 18 1999 664]. Following long term stimulation, ERK progressively accumulated in the nucleus in an inactive form. This nuclear retention relied on the neosynthesis of short-lived nuclear anchoring proteins. Nuclear inactivation and sequestration was likely to be controlled by MAP kinase phosphatases 1 and 2. Therefore we propose that the nucleus represents a site for ERK action, sequestration and signal termination [J Cell Sci 114 2001 3433].In addition, with the generation of mice invalidated for each of the ERK isoforms, we will illustrate that besides controlling cell proliferation the ERK cascade also controls cell differentiation and cell behaviour [Science 286 1999 1374].

Human cytomegalovirus genome sequences in lymph nodes

Human cytomegalovirus (CMV) is a major cause of morbidity in heart and lung transplant patients, resulting from immunosuppression-mediated reactivation of latent CMV originating either from the transplanted tissue, or the recipient. We showed that out of eight donor/recipient pairs, the lymph nodes (LNs) of three donors and four recipients, all CMV seropositive, harboured CMV DNA at exceeding levels compared with those of matched blood samples, as well as CMV RNA otherwise undetectable in patients' blood. On follow-up, patients positive for CMV DNA and RNA in LNs developed viraemia 4 to 5 weeks earlier than those initially polymerase chain reaction-negative for CMV. Our results indicate that LN are a significant site for sequestration and persistence of CMV and that LN may be important in seeding of CMV-infected cells into the circulation.

The Endothelial Cell and the Factor VIII Bypassing Activity of Prothrombin Complex Concentrate

Some classical hemophiliacs have a paradoxical hemostatic response to prothrombin complex concentrate (PCC). We hypothesized that vascular endothelial cells (EC) may contribute to this "factor VIII bypassing activity". When PCC were incubated with suspensions or monolayer cultures of EC, they acquired the ability to partially bypass the defect of factor VIII deficient plasma. This factor VIII bypassing activity distributed with EC and not with the supernatant PCC, and was not a general property of intravascular cells. The effect of PCC was even more dramatic on fixed EC monolayers, which became procoagulant after incubation with PCC. The time courses of association and dissociation of the PCC-derived factor VIII bypassing activity of fixed and viable EC monolayers were both rapid. We conclude that EC may provide a privileged site for sequestration of constituents of PCC which express coagulant activity and which bypass the abnormality of factor VIII deficient plasma.

Fetal Hematopoiesis—Case Report

Abstract An unusually well-preserved eleven-week, 4.7 cm. human fetus exhibited active erythropoiesis in liver, and myelopoiesis in femur and humerus; the spleen was the site for sequestration and destruction of primitive erythrocytes, and the yolk sac was fibrotic. High proportions of adult type hemoglobin (A) were found in liver homogenate, and an electrophoretically distinctive fetal form of G6PD was observed.