Carbon cycle in the coastal zone: effects of global perturbations and change in the past three centuries

Ver, Leah May; Mackenzie, Fred T.; Lerman, Abraham

doi:10.1016/s0009-2541(99)00042-x

Cited by 90 publications

(68 citation statements)

References 54 publications

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“…Although efforts have been made to evaluate the parameters that affect the carbon cycle and to model past and future 6534 C.-T. A. Chen et al: Air-sea exchanges of CO 2 in the world's coastal seas changes in carbon fluxes (Friederich et al, 2002;Fransson et al, 2006;Macpherson et al, 2008;Ver et al, 1999b, a;Mackenzie et al, 2000Mackenzie et al, , 2004Thomas et al, 2007;Borges, 2011), whether the size of the estuarine source and the continental shelf sink for CO 2 changes with time has not been determined because too few data are available. As stated above, the fact that the shelves are a sink rather than a source of CO 2 has only been established in the last few years.…”

Section: Temporal Changesmentioning

confidence: 99%

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

et al. 2013

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Abstract. The air-sea exchanges of CO 2 in the world's 165 estuaries and 87 continental shelves are evaluated. Generally and in all seasons, upper estuaries with salinities of less than two are strong sources of CO 2 (39 ± 56 mol C m −2 yr −1 , positive flux indicates that the water is losing CO 2 to the atmosphere); mid-estuaries with salinities of between 2 and 25 are moderate sources (17.5 ± 34 mol C m −2 yr −1 ) and lower estuaries with salinities of more than 25 are weak sources . Mixing with low-pCO 2 shelf waters, water temperature, residence time and the complexity of the biogeochemistry are major factors that govern the pCO 2 in estuaries, but wind speed, seldom discussed, is critical to controlling the air-water exchanges of CO 2 . The total annual release of CO 2 from the world's estuaries is now estimated to be 0.10 Pg C yr −1 , which is much lower than published values mainly because of the contribution of a considerable amount of heretofore unpublished or new data from Asia and the Arctic. The Asian data, although indicating high pCO 2 , are low in sea-to-air fluxes because of low wind speeds. Previously determined flux values rely heavily on data from Europe and North America, where pCO 2 is lower but wind speeds are much higher, such that the CO 2 fluxes are higher than in Asia. Newly emerged CO 2 flux data in the Arctic reveal that estuaries there mostly absorb rather than release CO 2 .Most continental shelves, and especially those at high latitude, are undersaturated in terms of CO 2 and absorb CO 2 from the atmosphere in all seasons. Shelves between 0 and 23.5 • S are on average a weak source and have a small flux per unit area of CO 2 to the atmosphere. Water temperature, the spreading of river plumes, upwelling, and biological production seem to be the main factors in determining pCO 2 in the shelves. Wind speed, again, is critical because at high latitudes, the winds tend to be strong. Since the surface water pCO 2 values are low, the air-to-sea fluxes are high in regions above 50 • N and below 50 • S. At low latitudes, the winds tend to be weak, so the sea-to-air CO 2 flux is small. Overall, the world's continental shelves absorb 0.4 Pg C yr −1 from the atmosphere.

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Section: Temporal Changesmentioning

confidence: 99%

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

et al. 2013

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“…The model describes the biogeochemical and physical transport behavior of these elements in the four domains of the Earth's surface: land, atmosphere, coastal ocean, and open ocean (Mackenzie and others, 1993;Ver, Mackenzie, and Lerman, 1994;Ver, Mackenzie, and Lerman, 1999). As defined in the model, the global surface environment is comprised of thirteen reservoirs ( fig.…”

Section: Model Structure and Analysismentioning

confidence: 99%

“…Many details of the model have been reported elsewhere (Mackenzie and others, 1993;Ver, Mackenzie, and Lerman, 1994;Ver, 1998). In the following sections, we describe only those model relationships and parameters that are particularly relevant to terrestrial and oceanic processes that redistribute anthropogenic CO 2 .…”

Section: Model Structure and Analysismentioning

confidence: 99%

“…T and T 1700 are the global temperatures at times t and in the year 1700, in units of°C. Although it is recognized that there are data, however sparse, to support values of Q 10 other than 2.0, the value of 2.0 is adopted as a working approximation in TOTEM (Ver, Mackenzie, and Lerman, 1994;Ver, 1998). Because the focus of interest with respect to changing temperature is the magnitude of change from the initial, steady-state condition, the temperature difference, ⌬T ϭ T Ϫ T 1700 , determines the change in the rate of photosynthesis.…”

Section: The Carbon Cycle To Natural and Human Perturbationsmentioning

confidence: 99%

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Biogeochemical responses of the carbon cycle to natural and human perturbations; past, present, and future

Ver

Mackenzie

Lerman

1999

American Journal of Science

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ABSTRACT. In the past three centuries, human perturbations of the environment have affected the biogeochemical behavior of the global carbon cycle and that of the other three nutrient elements closely coupled to carbon: nitrogen, phosphorus, and sulfur. The partitioning of anthropogenic CO 2 among its various sinks in the past, for the present, and for projections into the near future is controlled by the interactions of these four elemental cycles within the major environmental domains of the land, atmosphere, coastal oceanic zone, and open ocean. We analyze the past, present, and future behavior of the global carbon cycle using the Terrestrial-Ocean-aTmosphere Ecosystem Model (TOTEM), a unique process-based model of the four global coupled biogeochemical cycles of carbon, nitrogen, phosphorus, and sulfur. We find that during the past 300 yrs, anthropogenic CO 2 was mainly stored in the atmosphere and in the open ocean. Human activities on land caused an enhanced loss of mass from the terrestrial organic matter reservoirs (phytomass and humus) mainly through deforestation and consequently increased humus remineralization, erosion, and transport to the coastal margins by rivers and runoff. Photosynthetic uptake by the terrestrial phytomass was enhanced owing to fertilization by increasing atmospheric CO 2 concentrations and supported by nutrients remineralized from organic matter. TOTEM results indicate that through most of the past 300 yrs, the loss of C from deforestation and other land-use activities was greater than the gain from the enhanced photosynthetic uptake. During the decade of the 1980s, the terrestrial organic reservoirs were in rough carbon balance. Organic and carbonate carbon accumulating in coastal marine sediments is a small but significant sink for anthropogenic CO 2 . Increasing inputs of terrestrial organic matter and its subsequent oxidation in the coastal margin (increasing heterotrophy) were significant sources of CO 2 in coastal waters in the 20th century. However, the coastal ocean did not evolve into a greater net source of CO 2 to the atmosphere during this period because of the opposing pressure from rising atmospheric CO 2 . Since pre-industrial time (since 1700), the net flux of CO 2 from the coastal waters has decreased by 40 percent, from 0.20 Gt C/yr to 0.12 Gt C/yr. TOTEM analyses of atmospheric CO 2 concentrations for the 21st century were based on the fossil-fuel emission projections of IPCC (''business as usual'' scenario) and of the more restrictive UN 1997 Kyoto Protocol. By the mid-21st century, the projected atmospheric CO 2 concentrations range from about 550 ppmv (TOTEM, based on IPCC projected emissions) to 510 ppmv (IPCC projection) and to 460 ppmv (TOTEM, based on the Kyoto Protocol reduced emissions). The difference of about 40 ppmv between the IPCC and TOTEM estimates by the year 2050 reflects the different mechanisms within the C-N-P-S cycles on land that are built into our model. The effects of the reduced emissions prescribed by the Kyoto Protocol begin to sho...

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“…However, the intertidal is a significant component of the shallow-water ocean margin, is important in the global carbon cycle (Gattuso et al 1998b, Ver et al 1999, Chen et al 2003 and is a key habitat for many calcifying organisms. As yet, there is no published account of experimental apparatus that enables the combined effects of higher seawater temperatures and lower pH on intertidal habitats/organisms to be investigated.…”

Section: Introductionmentioning

confidence: 99%

Novel microcosm system for investigating the effects of elevated carbon dioxide and temperature on intertidal organisms

Findlay¹,

Kendall²,

Spicer³

et al. 2008

Aquat. Biol.

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In addition to the predicted rise in temperature, a recognised consequence of increased atmospheric CO 2 is ocean acidification. The response of marine organisms to the stresses associated with acidification is still not understood, and a number of recent experiments have addressed this problem. The starting point for many of these studies has been the development of a system by which seawater pH can be altered and then maintained. The current paper presents details of a temperature-and pH-controlled microcosm system, which enables the establishment of a tidal regime, for the experimental investigation of intertidal organisms. . The temperature and seawater carbonate chemistry were reliably maintained for 30 d during which time newly settled barnacle cyprids were allowed to metamorphose into juveniles, then grow and develop. The pH and [CO 2 ] had 95% confidence intervals of ± 0.03 units and ±17 ppm, respectively, under low [CO 2 ] conditions, and of ± 0.02 units and ± 43 ppm, respectively, under high [CO 2 ] conditions. The tidal regime is fully adjustable, and on this occasion was set to a 6 h cycle. These microcosms have proved ideal for studying benthic organisms from a variety of near-surface environments and at different stages of their life-cycle.

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Carbon cycle in the coastal zone: effects of global perturbations and change in the past three centuries

Cited by 90 publications

References 54 publications

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Biogeochemical responses of the carbon cycle to natural and human perturbations; past, present, and future

Novel microcosm system for investigating the effects of elevated carbon dioxide and temperature on intertidal organisms

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Carbon cycle in the coastal zone: effects of global perturbations and change in the past three centuries

Cited by 90 publications

References 54 publications

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Air–sea exchanges of CO&lt;sub&gt;2&lt;/sub&gt; in the world's coastal seas

Biogeochemical responses of the carbon cycle to natural and human perturbations; past, present, and future

Novel microcosm system for investigating the effects of elevated carbon dioxide and temperature on intertidal organisms

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Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas

Air–sea exchanges of CO<sub>2</sub> in the world's coastal seas