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Mackenzie, FT, Andersson A.  2010.  Biological control on diagenesis: influence of bacteria and relevance to ocean acidification. Encyclopedia of Geobiology. Abstract
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Mackenzie, FT, Lerman A, Andersson AJ.  2004.  Past and present of sediment and carbon biogeochemical cycling models. Biogeosciences. 1:11-32. AbstractWebsite

The global carbon cycle is part of the much more extensive sedimentary cycle that involves large masses of carbon in the Earth's inner and outer spheres. Studies of the carbon cycle generally followed a progression in knowledge of the natural biological, then chemical, and finally geological processes involved, culminating in a more or less integrated picture of the biogeochemical carbon cycle by the 1920s. However, knowledge of the ocean's carbon cycle behavior has only within the last few decades progressed to a stage where meaningful discussion of carbon processes on an annual to millennial time scale can take place. In geologically older and pre-industrial time, the ocean was generally a net source of CO2 emissions to the atmosphere owing to the mineralization of land-derived organic matter in addition to that produced in situ and to the process of CaCO3 precipitation. Due to rising atmospheric CO2 concentrations because of fossil fuel combustion and land use changes, the direction of the air-sea CO2 flux has reversed, leading to the ocean as a whole being a net sink of anthropogenic CO2. The present thickness of the surface ocean layer, where part of the anthropogenic CO2 emissions are stored, is estimated as of the order of a few hundred meters. The oceanic coastal zone net air-sea CO2 exchange flux has also probably changed during industrial time. Model projections indicate that in preindustrial times, the coastal zone may have been net heterotrophic, releasing CO2 to the atmosphere from the imbalance between gross photosynthesis and total respiration. This, coupled with extensive CaCO3 precipitation in coastal zone environments, led to a net flux of CO2 out of the system. During industrial time the coastal zone ocean has tended to reverse its trophic status toward a non-steady state situation of net autotrophy, resulting in net uptake of anthropogenic CO2 and storage of carbon in the coastal ocean, despite the significant calcification that still occurs in this region. Furthermore, evidence from the inorganic carbon cycle indicates that deposition and net storage of CaCO3 in sediments exceed inflow of inorganic carbon from land and produce CO2 emissions to the atmosphere. In the shallow-water coastal zone, increase in atmospheric CO2 during the last 300 years of industrial time may have reduced the rate of calcification, and continuation of this trend is an issue of serious environmental concern in the global carbon balance.

Mackenzie, FT, Andersson AJ, Arvidson RS, Guidry MW, Lerman A.  2011.  Land-sea carbon and nutrient fluxes and coastal ocean CO(2) exchange and acidification: Past, present, and future. Applied Geochemistry. 26:S298-S302.   10.1016/j.apgeochem.2011.03.087   AbstractWebsite

Epochs of changing atmospheric CO(2) and seawater CO(2)-carbonic acid system chemistry and acidification have occurred during the Phanerozoic at various time scales. On the longer geologic time scale, as sea level rose and fell and continental free board decreased and increased, respectively, the riverine fluxes of Ca, Mg, DIC, and total alkalinity to the coastal ocean varied and helped regulate the C chemistry of seawater, but nevertheless there were major epochs of ocean acidification (OA). On the shorter glacial-interglacial time scale from the Last Glacial Maximum (LGM) to late preindustrial time, riverine fluxes of DIC, total alkalinity, and N and P nutrients increased and along with rising sea level, atmospheric PCO(2) and temperature led, among other changes, to a slightly deceasing pH of coastal and open ocean waters, and to increasing net ecosystem calcification and decreasing net heterotrophy in coastal ocean waters. From late preindustrial time to the present and projected into the 21st century, human activities, such as fossil fuel and land-use emissions of CO(2) to the atmosphere, increasing application of N and P nutrient subsidies and combustion N to the landscape, and sewage discharges of C, N, P have led, and will continue to lead, to significant modifications of coastal ocean waters. The changes include a rapid decline in pH and carbonate saturation state (modern problem of ocean acidification), a shift toward dissolution of carbonate substrates exceeding production, potentially leading to the "demise" of the coral reefs, reversal of the direction of the sea-to-air flux of CO(2) and enhanced biological production and burial of organic C, a small sink of anthropogenic CO(2), accompanied by a continuous trend toward increasing autotrophy in coastal waters. (C) 2011 Elsevier Ltd. All rights reserved.

Mackenzie, FT, Andersson A, et al.  2004.  Boundary exchanges in the global coastal margin: implications for the organic and inorganic carbon cycles. Sea Volume. 13, the global coastal oceanocean: multiscale interdisciplinary processes. ( Robinson A, Brinks K, Eds.)., MA: Harvard University press Abstract
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Mackenzie, FT, Andersson AJ.  2013.  The marine carbon system and ocean acidification during Phanerozoic time. Geochemical Perspectives. 2:1-227.   10.7185/geochempersp.2.1   AbstractWebsite

The global CO2-carbonic acid-carbonate system of seawater, although certainly a well-researched topic of interest in the past, has risen to the fore in recent years because of the environmental issue of ocean acidification (often simply termed OA). Despite much previous research, there remain pressing questions about how this most important chemical system of seawater operated at the various time scales of the deep time of the Phanerozoic Eon (the past 545 Ma of Earth's history), interglacial-glacial time, and the Anthropocene (the time of strong human influence on the behaviour of the system) into the future of the planet. One difficulty in any analysis is that the behaviour of the marine carbon system is not only controlled by internal processes in the ocean, but it is intimately linked to the domains of the atmosphere, continental landscape, and marine carbonate sediments.

Marshall, J, Andersson A, Bates N, Dewar W, Doney S, Edson J, Ferrari R, Forget G, Fratantoni D, Gregg M, Joyce T, Kelly K, Lozier S, Lumpkin R, Maze G, Palter J, Samelson R, Silverthorne K, Skyllingstad E, Straneo F, Talley L, Thomas L, Toole J, Weller R, Climode G.  2009.  The CLIMODE FIELD CAMPAIGN Observing the Cycle of Convection and Restratification over the Gulf Stream. Bulletin of the American Meteorological Society. 90:1337-1350.   10.1175/2009bams2706.1   AbstractWebsite
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McLeod, E, Anthony KRN, Andersson A, Beeden R, Golbuu Y, Kleypas J, Kroeker K, Manzello D, Salm RV, Schuttenberg H, Smith JE.  2013.  Preparing to manage coral reefs for ocean acidification: lessons from coral bleaching. Frontiers in Ecology and the Environment. 11:20-27.   10.1890/110240   AbstractWebsite

Ocean acidification is a direct consequence of increasing atmospheric carbon dioxide concentrations and is expected to compromise the structure and function of coral reefs within this century. Research into the effects of ocean acidification on coral reefs has focused primarily on measuring and predicting changes in seawater carbon (C) chemistry and the biological and geochemical responses of reef organisms to such changes. To date, few ocean acidification studies have been designed to address conservation planning and management priorities. Here, we discuss how existing marine protected area design principles developed to address coral bleaching may be modified to address ocean acidification. We also identify five research priorities needed to incorporate ocean acidification into conservation planning and management: (1) establishing an ocean C chemistry baseline, (2) establishing ecological baselines, (3) determining species/habitat/community sensitivity to ocean acidification, (4) projecting changes in seawater carbonate chemistry, and (5) identifying potentially synergistic effects of multiple stressors.

MeQuaid, JB, Kustka AB, Obornik M, Horak A, McCrow JR, Karas BJ, Zheng H, Kindeberg T, Andersson AJ, Barbeau KA, Allen AE.  2018.  Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms. Nature. 555:534-+.   10.1038/nature25982   AbstractWebsite

In vast areas of the ocean, the scarcity of iron controls the growth and productivity of phytoplankton(1,2). Although most dissolved iron in the marine environment is complexed with organic molecules(3), picomolar amounts of labile inorganic iron species (labile iron) are maintained within the euphotic zone(4) and serve as an important source of iron for eukaryotic phytoplankton and particularly for diatoms(5). Genome-enabled studies of labile iron utilization by diatoms have previously revealed novel iron responsive transcripts(6,7), including the ferric iron-concentrating protein ISIP2A(8), but the mechanism behind the acquisition of picomolar labile iron remains unknown. Here we show that ISIP2A is a phytotransferrin that independently and convergently evolved carbonate ion-coordinated ferric iron binding. Deletion of ISIP2A disrupts high-affinity iron uptake in the diatom Phaeodactylum tricornutum, and uptake is restored by complementation with human transferrin. ISIP2A is internalized by endocytosis, and manipulation of the seawater carbonic acid system reveals a second order dependence on the concentrations of labile iron and carbonate ions. In P. tricornutum, the synergistic interaction of labile iron and carbonate ions occurs at environmentally relevant concentrations, revealing that carbonate availability co-limits iron uptake. Phytotransferrin sequences have a broad taxonomic distribution(8) and are abundant in marine environmental genomic datasets(9,10), suggesting that acidification-driven declines in the concentration of seawater carbonate ions will have a negative effect on this globally important eukaryotic iron acquisition mechanism.

Morse, JW, Andersson AJ, Mackenzie FT.  2006.  Initial responses of carbonate-rich shelf sediments to rising atmospheric pCO(2) and "ocean acidification": Role of high Mg-calcites. Geochimica Et Cosmochimica Acta. 70:5814-5830.   10.1016/j.gca.2006.08.017   AbstractWebsite

Carbonate-rich sediments at shoal to shelf depths (< 200 m) represent a major CaCO(3) reservoir that can rapidly react to the decreasing saturation state of seawater with respect to carbonate minerals, produced by the increasing partial pressure of atmospheric carbon dioxide (pCO(2)) and "acidification" of ocean waters. Aragonite is usually the most abundant carbonate mineral in these sediments. However, the second most abundant (typically similar to 24 wt%) carbonate mineral is high Mg-calcite (Mg-calcite) whose solubility can exceed that of aragonite making it the "first responder" to the decreasing saturation state of seawater. For the naturally occurring biogenic Mg-calcites, dissolution experiments have been used to predict their "stoichiometric solubilities" as a function of mol% MgCO(3). The only valid relationship that one can provisionally use for the metastable stabilities for Mg-calcite based on composition is that for the synthetically produced phases where metastable equilibrium has been achieved from both under- and over-saturation. Biogenic Mg-calcites exhibit a large offset in solubility from that of abiotic Mg-calcite and can also exhibit a wide range of solubilities for biogenic Mg-calcites of similar Mg content. This indicates that factors other than the Mg content can influence the solubility of these mineral phases. Thus, it is necessary to turn to observations of natural sediments where changes in the saturation state of surrounding waters occur in order to determine their likely responses to the changing saturation state in upper oceanic waters brought on by increasing pCO(2). In the present study, we investigate the responses of Mg-calcites to rising pCO(2) and "ocean acidification" by means of a simple numerical model based on the experimental range of biogenic Mg-calcite solubilities as a function of Mg content in order to bracket the behavior of the most abundant Mg-calcite phases in the natural environment. In addition, observational data from Bermuda and the Great Bahama Bank are also presented in order to project future responses of these minerals. The numerical simulations suggest that Mg-calcite minerals will respond to rising pCO(2) by sequential dissolution according to mineral stability, progressively leading to removal of the more soluble phases until the least soluble phases remain. These results are confirmed by laboratory experiments and observations from Bermuda. As a consequence of continuous increases in atmospheric CO, from burning of fossil fuels, the average composition of contemporary carbonate sediments could change, i.e., the average Mg content in the sediments may slowly decrease. Furthermore, evidence from the Great Bahama Bank indicates that the amount of abiotic carbonate production is likely to decline as pCO(2) continues to rise. (c) 2006 Elsevier Inc. All rights reserved.