AbstractWe estimated long-term trends of ocean acidification in surface waters in latitudinal zones from 3°N to 33°N along the repeat hydrographic line at 137°E in the western North Pacific Ocean. Estimates were based on the observational records of oceanic CO2 partial pressure and related surface properties over the last two decades. The computed pH time series both for 25 yr in winter (late January.early February) and for 21 yr in summer (June.July) exhibited significant decreasing trends in the extensive subtropical to equatorial zones, with interannual variations that were larger in summer. The calculated rates of pH decrease ranged from 0.0015 to 0.0021 yr-1 (average, 0.0018 ± 0.0002 yr-1) in winter and from 0.0008 to 0.0019 yr-1 (average, 0.0013 ) 0.0005 yr-1) in summer. The thermodynamic effects of rising sea surface temperature (SST) accounted for up to 44% (average, 15%) of the trend of pH decrease in the subtropical region in winter, whereas a trend of decreasing SST slowed the pH decrease in the northern subtropical region (around 25°N) in summer. We used the results from recent trends to evaluate future possible thermodynamic changes in the upper ocean carbonate system.
During 1968 to 72, scientists of the Meteorological Research Institute/Japan Meteorological Agency measured CO2 in the surface seawater and overlying air in the Pacific Ocean quasicontinuously to examine CO2 exchange between the sea and the atmosphere. From the data remaining in our laboratory from that time, we re-evaluated the partial pressure of CO2 in surface seawater (pCOs2) by taking into account pressure broadening effects due to the use of CO2-in-N2 standards, the use of chemical desiccant (Mg(ClO4)2), calibration using background air data, seawater temperature rise between the equilibrator and sea surface, the WMO CO2 mole fraction scale, and differences in pressure during the oceanic CO2 measurements from those of standards and background air in the nondispersive infra-red gas analyser cell. The overall uncertainty of pCOs2 measurements for the cruises from 1968 to 1970 was estimated to be less than 3.6 ¼atm, which allowed us to evaluate temporal variations in the carbonate system over a few decades, but uncertainty was higher (¾ 10 ¼atm) for the cruise from 1971 to 1972 because of serious malfunctions of the system. The re-evaluated pCOs2 data from 1968 to 1970 exhibit patterns similar to those observed at the same place and time of year (within 30 days) in 1982/83, 1988, 1995 and 1996, but compared with levels in the 1980s and 1990s the pCOs2 level was clearly lower in the wide area of the Pacific except south of the Subtropical Front (STF; 47°S) in the Australian sector. The observed pCOs2 increased by 34 ±5 ¼atm (n = 133) for the area 7°N to 35°N, 138°E to 147°E from February 1969 to February 1995, 29 ±5 ¼atm (n = 247) for the area 9°N to 35°N, 138°E to 165°E from February 1970 to February/March 1996, 26 ±7 ¼atm (n = 224) for the area 29°N to 51°N, 170°W from April 1970 to April 1988, and 41 ±9 ¼atm (n = 165) for the area 10°S to 45°S, 148°E to 166°E from January/February 1969 to January/February 1995. In the northern subtropics (7°N to 35°N, 138°E to 147°E), we estimated the long-term increase (35 ±6 ¼atm, n= 133) after removing seasonal variations that were obtained from the pCOs2-sea surface temperature (SST) relationship. Observed and seasonally adjusted increases were nearly equal to those of the partial pressure of CO2 in the air (1.4 ¼atm yr-1) over the same time intervals. South of the STF, pCOs2 increase as found in the subtropics was not detected, mostly due to the large variability of pCOs2 (250 to 380 ¼atm in 1968/69) on small spatial scales. The average pCOs2 south of the STF showed large variations on time scales of months and years that affect the estimation of the growth rate of atmospheric CO2.
We estimated long-term trends of ocean acidification in surface waters in latitudinal zones from 3°N to 33°N along the repeat hydrographic line at 137°E in the western North Pacific Ocean.Estimates were based on the observational records of oceanic CO 2 partial pressure and related surface properties over the last two decades.The computed pH time series both for 25 years in winter (late January to early February) and for 21 years in summer (June to July) exhibited significant decreasing trends in the extensive subtropical to equatorial zones, with interannual variations that were larger in summer.The calculated rates of pH decrease ranged from 0.0015 to 0.0021 yr -1 (average, 0.0018 ± 0.0002 yr -1 ) in winter and from 0.0008 to 0.0019 yr -1 (average, 0.0013 ± 0.0005 yr -1 ) in summer.The thermodynamic effects of rising sea surface temperature (SST) accounted for up to 44% (average, 15%) of the trend of pH decrease in the subtropical region in winter, whereas a trend of decreasing SST slowed the pH decrease in the northern subtropical region (around 25°N) in summer.We used the results from recent trends to evaluate future possible thermodynamic changes in the upper ocean carbonate system.
Poly[( R )-3-hydroxybutyrate- co -( R )-3-hydroxyhexanoate] [P(3HB- co -3HHx)] is a practical kind of bacterial polyhydroxyalkanoates (PHAs). A previous study has established an artificial pathway for the biosynthesis of P(3HB- co -3HHx) from structurally unrelated sugars in Ralstonia eutropha , in which crotonyl-CoA carboxylase/reductase (Ccr) and ethylmalonyl-CoA decarboxylase (Emd) are a key combination for generation of butyryl-CoA and the following chain elongation. This study focused on the installation of the artificial pathway into Escherichia coli . The recombinant strain of E. coli JM109 harboring 11 heterologous genes including Ccr and Emd produced P(3HB- co -3HHx) composed of 14 mol% 3HHx with 41 wt% of dry cellular weight from glucose. Further investigations revealed that the C 6 monomer ( R )-3HHx-CoA was not supplied by ( R )-specific reduction of 3-oxohexanoyl-CoA but by ( R )-specific hydration of 2-hexenoyl-CoA formed through reverse β-oxidation after the elongation from C 4 to C 6 . While contribution of the reverse β-oxidation to the conversion of the C 4 intermediates was very limited, crotonyl-CoA, a precursor of butyryl-CoA, was generated by dehydration of ( R )-3HB-CoA. Several modifications previously reported for enhancement of bioproduction in E. coli were examined for the copolyester synthesis. Elimination of the global regulator Cra or PdhR as well as the block of acetate formation resulted in poor PHA synthesis. The strain lacking RNase G accumulated more PHA but with almost no 3HHx unit. Introduction of the phosphite oxidation system for regeneration of NADPH led to copolyester synthesis with the higher cellular content and higher 3HHx composition by two-stage cultivation with phosphite than those in the absence of phosphite.
Spatial and temporal variations in the concentration of phosphorus pools, including total phosphorus (TP), reactive phosphorus (RP), and nonreactive phosphorus (NP), were evaluated in subtropical regions (10–30°N) of the western North Pacific Ocean along 137°E through eight sampling periods from summer 2003 to spring 2005. RP was depleted at the water surface throughout our observation, varying less than 0.1 μ M. The low concentration of RP was restricted to the surface mixing layer, and the concentration obviously increased concomitant with the decrease in water temperature. NP concentration was generally highest at the water surface and gradually decreased with increasing depth, but the depth and temporal variations were not definite compared with those of RP. NP was further divided into two fractions depending on its reactivity to specific ultraviolet (UV) irradiation. The concentration of UV labile organic phosphorus (UVL OP) was consistently low, being comparable with that of RP; their inventories from 0 to 50 m of RP and UVL OP fluctuated with in the range of 0.9–3.2 and 2.0–3.1 mmol m −2 , respectively. As for incubation experiments in coastal waters using glucose‐1‐phosphate, which is fractionated into UVL OP, the UVL OP most likely has a short turnover time due to rapid utilization by microorganisms, indicating a significant role in the phosphorus cycle through the microbial food web. Inventory of the UV stable OP (UVS OP), on the other hand, varied nearly eightfold in the upper 50 m, and the temporal change in TP inventory was exclusively due to that of UVS OP.
Abstract Spatiotemporal variations in air‐sea CO 2 fluxes in the Kuroshio region were evaluated using measurements made by voluntary cargo ships and research vessels. The data were re‐gridded to produce a 1° × 1° horizontal grid and 0.1‐year timesteps. Spatial clustering showed that the area north of approximately 30°N was the strongest atmospheric CO 2 sink. The spatial differences were largest in winter and insignificant in summer. The oceanic CO 2 uptake in the Kuroshio region increased from 2000 to 2019. Changes in the wind speed and total alkalinity affected the decadal increase in CO 2 absorption. The spatial distributions of the air‐sea CO 2 fluxes were affected by the Kuroshio large meander (KLM). This effect was likely caused by the change in seawater fCO 2 via the change in the Kuroshio Extension Path during the KLM period. The Fourier regression technique used in the data analysis was expected to facilitate analyses of the carbonate system in coastal waters, where comprehensive on‐site measurements and satellite analyses are difficult.
Characteristics of temporal variation in the vertical profile of total organic carbon (TOC) were investigated in the upper layer of the ocean at various latitudes (10–30°N) of 137°E in the western North Pacific subtropical gyre. Bulk TOC was divided into labile and stable fractions by the specific UV irradiation to evaluate their contributions to the temporal fluctuation of TOC. Authentic specimens and dissolved organic carbon collected from coastal waters were used to examine the correspondence between the photochemical reactivity to the specific UV irradiation and biological reactivity. The concentration of TOC in the upper layer was higher in summer when the surface layer is well stratified and was lower in winter when the mixed layer deepened. Although the winter mixed layer is shallower in lower latitudes, the amplitude of the seasonal variations in the top 50 m weighted mean TOC concentration (19.5–27.7 μ M) did not vary considerably over the subtropical zones we studied. A major fraction (51.9–89.8%) of TOC was stable against specific UV irradiation and was thought to be mainly composed of biologically stable organic compounds, but the seasonal variation of TOC at each latitude was mainly attributable to the variation of UV labile fraction. This finding suggests that the seasonal variation of TOC in the upper layer is explained by the biological production of TOC in summer surface water and its vertical mixing with low UV, labile TOC in winter. Upward advection of subsurface water due to the passage of cyclonic eddies and changes in the geostrophic current are also likely to affect the temporal TOC variation, in particular, in the lower latitudes where winter mixed layer and permanent thermocline are shallower.
Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2005–2014), EFF was 9.0 ± 0.5 GtC yr−1, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 4.4 ± 0.1 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1, and SLAND was 3.0 ± 0.8 GtC yr−1. For the year 2014 alone, EFF grew to 9.8 ± 0.5 GtC yr−1, 0.6 % above 2013, continuing the growth trend in these emissions, albeit at a slower rate compared to the average growth of 2.2 % yr−1 that took place during 2005–2014. Also, for 2014, ELUC was 1.1 ± 0.5 GtC yr−1, GATM was 3.9 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 4.1 ± 0.9 GtC yr−1. GATM was lower in 2014 compared to the past decade (2005–2014), reflecting a larger SLAND for that year. The global atmospheric CO2 concentration reached 397.15 ± 0.10 ppm averaged over 2014. For 2015, preliminary data indicate that the growth in EFF will be near or slightly below zero, with a projection of −0.6 [range of −1.6 to +0.5] %, based on national emissions projections for China and the USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the global economy for the rest of the world. From this projection of EFF and assumed constant ELUC for 2015, cumulative emissions of CO2 will reach about 555 ± 55 GtC (2035 ± 205 GtCO2) for 1870–2015, about 75 % from EFF and 25 % from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2015).
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