A framework for assessing the role of karst conduit morphology, hydrology, and evolution in the transport and storage of carbon and associated sediments

Karst aquifers and conduits form by dissolution of carbonate minerals and the slow release of inorganic carbon to the surface environment. As conduits evolve in size, morphology, and position within the aquifer, their function and capacity change relative to the storage and transport of inorganic and organic carbon as sediment. Conduits serve mostly as transport mechanisms in relation to sediments. Quantified data are sparse, but for conduits to function effectively there must be at least equilibrium in the amount of sediment entering and exiting the aquifer. If sediment discharge exceeds input, little sediment will remain underground. When natural declines in base level cease removing sediments and only deposit calcite speleothems, these materials are stored until the rock mass is denuded. While sediment storage is mostly transient in hydrologically active conduits, relative differences occur. Aquifers with conduits developed at multiple levels or as floodwater mazes store proportionately greater volumes of sediment. Hypogenic systems should store greater volumes of sediment than epigenic aquifers because they mostly discharge a dissolved load as opposed to both dissolved and suspended clastic loads. However, some hypogenic aquifers are diffusely recharged and receive and store little sediment from the surface. The global volume of sediment and organic carbon stored in karst aquifers is estimated in this study to be on the order of 2x104 km3and 2x102 km3, respectively. The amount of organic carbon stored in paleokarst is not estimated, but available data indicate it is substantially greater than that stored in modern karst aquifers. Development of such data may suggest that paleokarst petroleum reservoirs might serve as efficient carbon sinks for global carbon sequestration. Hydrocarbon-depleted paleokarst reservoirs should provide substantially more storage per injection well than sequestration in non-paleokarstic rocks.Keywords: Sediment, carbon, paleokarst, conduit morphology, karst hydrology, sequestration.DOI: 10.3986/ac.v42i2-3.66

Effects of Urbanization on the Quantity and Quality of Storm Water Runoff Recharging Through Caves into the Edwards Aquifer, Bexar County, Texas

Eighty-nine caves and sinkholes were investigated in the Edwards Aquifer recharge zone in Bexar County, Texas. The study examined their hydrogeologic and topographic origins and distribution, relationships to major fracture traces, quantity of recharge into the aquifer and degree of sensitivity towards degradation of the aquifer’s water quality. Groundwater traces were attempted to determine aquifer flow routes, time of groundwater travel, groundwater volume within conduits, and the aquifer’s capacity for dilution and dispersion of recharged contaminants. Trends in water quality were examined to quantify the volume and variety of contaminants recharged into the aquifer and to determine the effects of urbanization upon the Edwards Aquifer. The Edwards recharge zone was hydrogeologically assessed to rate the sensitivity of its areas. Socio-political impacts on recharge zone development were also examined. Based on the results of the above outlined research method, the conclusions of this investigation are that caves and sinkholes contribute substantial recharge into the Edwards Aquifer, rapidly transmit that recharge to the aquifer and are sensitive sites for potential contamination. The entire recharge zone was determined to be very sensitive to contamination. No significant differences were found between areas within the recharge zone to scale their degree of sensitivity. Major conduit flow networks were found to exist within the aquifer and their groundwater flow paths could be traced. Urban development of the Edwards recharge zone was shown to decrease the volume of recharge and degrade the aquifer’s water quality. No significant detrimental effects on the aquifer were observed. The volume of diminished recharge and the concentration of recharged contaminants that were necessary to produce significant adverse effects on the aquifer were not determined due to lack of precipitation during the study period and inconclusive groundwater tracings. It was recommended that further development of the recharge zone be suspended until the effects of urbanization are quantified

Global distribution of carbonate rocks and karst water resources

Karstregionen beinhalten eine Vielzahl natürlicher Ressourcen, wie Süßwasser und Biodiversität, sowie zahlreiche kulturelle und historische Ressourcen. Die Welt-Karstaquifer-Karte (WOKAM) ist die erste detaillierte und vollständige globale Datenbasis über die Verbreitung von verkarstungsfähigen Gesteinen (Carbonate und Evaporite), welche potentielle Karstaquifere darstellen. Diese Studie präsentiert eine statistische Auswertung von WOKAM, mit dem Fokus auf Karst in Carbonatgesteinen, und adressiert vier wesentliche Aspekte: (i) globales Vorkommen und geografische Verteilung von Karst; (ii) Karst in verschiedenen topografischen Settings und in Küstengebieten; (iii) Karst in verschiedenen Klimazonen; und (iv) Bevölkerung in Karstgebieten. Die Analyse ergibt, dass 15,2 % der globalen, eisfreien Kontinentalfläche durch Carbonatgesteine charakterisiert sind. Der höchste prozentuale Anteil tritt in Europa auf (21,8 %); die größte absolute Fläche in Asien (8,35 Mio. km²). Weltweit treten 31,1 % aller anstehenden Carbonatgesteine in Ebenen auf, 28,1 % im Hügelland und 40,8 % in Gebirgen; 151,400 km oder 15,7 % der globalen marinen Küstenlinie wird von Carbonatgesteinen geprägt. Etwa 34,2 % aller Carbonatgesteine kommen im ariden Klima vor, gefolgt von 28,2 % in kalten und 15,9 % in gemäßigten Klimaten, während nur 13,1 % bzw. 8,6 % im tropischen bzw. polaren Klima anzutreffen sind. Global leben etwa 1,18 Milliarden Menschen (16,5 % der Weltbevölkerung) in Karstgebieten. Die höchste absolute Anzahl wurde in Asien ermittelt (661,7 Mio.), während die höchsten prozentualen Anteile in Europa (25,3 %) und Nordamerika (23,5 %) auftreten. Diese Ergebnisse zeigen die globale Bedeutung von Karst und dienen als Basis für weitere Forschung und internationale Wassermanagement-Strategien

Global distribution of carbonate rocks and karst water resources

Karstregionen beinhalten eine Vielzahl natürlicher Ressourcen, wie Süßwasser und Biodiversität, sowie zahlreiche kulturelle und historische Ressourcen. Die Welt-Karstaquifer-Karte (WOKAM) ist die erste detaillierte und vollständige globale Datenbasis über die Verbreitung von verkarstungsfähigen Gesteinen (Carbonate und Evaporite), welche potentielle Karstaquifere darstellen. Diese Studie präsentiert eine statistische Auswertung von WOKAM, mit dem Fokus auf Karst in Carbonatgesteinen, und adressiert vier wesentliche Aspekte: (i) globales Vorkommen und geografische Verteilung von Karst; (ii) Karst in verschiedenen topografischen Settings und in Küstengebieten; (iii) Karst in verschiedenen Klimazonen; und (iv) Bevölkerung in Karstgebieten. Die Analyse ergibt, dass 15,2 % der globalen, eisfreien Kontinentalfläche durch Carbonatgesteine charakterisiert sind. Der höchste prozentuale Anteil tritt in Europa auf (21,8 %); die größte absolute Fläche in Asien (8,35 Mio. km²). Weltweit treten 31,1 % aller anstehenden Carbonatgesteine in Ebenen auf, 28,1 % im Hügelland und 40,8 % in Gebirgen; 151,400 km oder 15,7 % der globalen marinen Küstenlinie wird von Carbonatgesteinen geprägt. Etwa 34,2 % aller Carbonatgesteine kommen im ariden Klima vor, gefolgt von 28,2 % in kalten und 15,9 % in gemäßigten Klimaten, während nur 13,1 % bzw. 8,6 % im tropischen bzw. polaren Klima anzutreffen sind. Global leben etwa 1,18 Milliarden Menschen (16,5 % der Weltbevölkerung) in Karstgebieten. Die höchste absolute Anzahl wurde in Asien ermittelt (661,7 Mio.), während die höchsten prozentualen Anteile in Europa (25,3 %) und Nordamerika (23,5 %) auftreten. Diese Ergebnisse zeigen die globale Bedeutung von Karst und dienen als Basis für weitere Forschung und internationale Wassermanagement-Strategien

Allele-Specific HLA Loss and Immune Escape in Lung Cancer Evolution

Immune evasion is a hallmark of cancer. Losing the ability to present neoantigens through human leukocyte antigen (HLA) loss may facilitate immune evasion. However, the polymorphic nature of the locus has precluded accurate HLA copy-number analysis. Here, we present loss of heterozygosity in human leukocyte antigen (LOHHLA), a computational tool to determine HLA allele-specific copy number from sequencing data. Using LOHHLA, we find that HLA LOH occurs in 40% of non-small-cell lung cancers (NSCLCs) and is associated with a high subclonal neoantigen burden, APOBEC-mediated mutagenesis, upregulation of cytolytic activity, and PD-L1 positivity. The focal nature of HLA LOH alterations, their subclonal frequencies, enrichment in metastatic sites, and occurrence as parallel events suggests that HLA LOH is an immune escape mechanism that is subject to strong microenvironmental selection pressures later in tumor evolution. Characterizing HLA LOH with LOHHLA refines neoantigen prediction and may have implications for our understanding of resistance mechanisms and immunotherapeutic approaches targeting neoantigens. Video Abstract [Figure presented] Development of the bioinformatics tool LOHHLA allows precise measurement of allele-specific HLA copy number, improves the accuracy in neoantigen prediction, and uncovers insights into how immune escape contributes to tumor evolution in non-small-cell lung cancer

Fc-Optimized Anti-CD25 Depletes Tumor-Infiltrating Regulatory T Cells and Synergizes with PD-1 Blockade to Eradicate Established Tumors

CD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (FcγR) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating FcγRs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology

Fc Effector Function Contributes to the Activity of Human Anti-CTLA-4 Antibodies.

With the use of a mouse model expressing human Fc-gamma receptors (FcγRs), we demonstrated that antibodies with isotypes equivalent to ipilimumab and tremelimumab mediate intra-tumoral regulatory T (Treg) cell depletion in vivo, increasing the CD8+ to Treg cell ratio and promoting tumor rejection. Antibodies with improved FcγR binding profiles drove superior anti-tumor responses and survival. In patients with advanced melanoma, response to ipilimumab was associated with the CD16a-V158F high affinity polymorphism. Such activity only appeared relevant in the context of inflamed tumors, explaining the modest response rates observed in the clinical setting. Our data suggest that the activity of anti-CTLA-4 in inflamed tumors may be improved through enhancement of FcγR binding, whereas poorly infiltrated tumors will likely require combination approaches

Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies

Brazilian cave heritage under siege

info:eu-repo/semantics/publishe