Theoretical Background

In terrestrial ecosystems, photosynthesis by vegetation is the major sink of atmospheric CO2, while microbial respiration is the major source of CO2 into the atmosphere. Since these two processes behave independently under changing environmental conditions, it is ideal to estimate both the net photosynthesis and the microbial respiration separately at high temporal and geospatial resolution for quantitative assessment of carbon budget. Nevertheless, this has never been realized to date even...

Effects of Burning on the Availability of Nutrients of the Topsoil

One of the main advantages of slash-and-burn agriculture for crop growth is the rapid release of mineral nutrients stored in the litter and soil organic matter (SOM). The nutrient most effectively enhanced through burning at this site was phosphorus (Fig. 3a), which is consistent with results reported from a number of studies in tropical regions (Nakano, 1978 Tulaphitak et al., 1985a Romanya et al., 1994 Juo and Manu, 1996). The exchangeable cations in the topsoils also significantly increased...

Carbon Fixation Rate

A depth and time resolved primary productivity model was proposed to estimate primary productivity from satellite measurement (Asanuma et al., 2000, 2001a, b). A vertical distribution of PAR is defined by an empirical equation as a function of the chlorophyll a concentration in the surface. A vertical distribution of chlorophyll a concentration is also defined by an empirical equation as a function of the vertical distribution of PAR. A carbon fixation rate is defined as a function of PAR and...

Coral 18O Record of SST at Ishigaki Island

The Porites australiensis colony (IU96-07) in Urasoko Bay, Ishigaki Island, is only 300 m from a long-term daily temperature monitoring station (Yaeyama Station, Japan Sea-Farming Association). Therefore, this coral specimen was considered a good material for the calibration of the skeletal 818Oc response to changes in SST (Figs. 3 and 4). Suzuki et al. (1999) proposed the following skeletal 818Oc-SST relationship (Fig. 5) 818Oc( ) - -0.611 - 0.165T ( C). (1) The seasonal variation of SST...

Definition of Waters

Oyashio waters (subarctic), the Oyashio-Kuroshio transition, and Kuroshio waters (subtropic) were distinguished according to Kawai's (1972) definition, using the temperature at a depth of 100 or 200 m. This study uses the term Oyashio-transition waters'' to describe the area including Oyashio waters and the Kuroshio-Oyashio transition. A fixed station (lat 33 12'54''N, long 133 23'36E) in Tosa Bay with a bottom depth of 100 m was located inshore northwest of Kuroshio waters. The East China Sea...

References

M., Morel, A., 1996. Oceanic primary production. 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll. Global Biogeochemical Cycles 10 (1), 57-69. Cho, B. C., Azam, F., 1988. Major role of bacteria in biogeochemical fluxes in the ocean's interior. Nature 332, 441-443. Cowie, G. L., Hedges, J. I., 1994. Biochemical indicators of diagenetic alteration in natural organic matter mixtures. Nature 369, 304-307. Dauwe, B., Middelburg, J. J.,...

Discussion and Conclusion

Upper ocean temperature variability within the Indonesian seas and southeast Indian Ocean has been described on the basis of repeat high-quality XBT data collected since 1983. The observations have been compared to results from an eddy-permitting ocean circulation model. Besides strong annual variability in the seasonal thermocline and in the thermoclines off the Arafura and Java shelf breaks in both data sets, interannual variability dominates much of the thermocline variability elsewhere....

Production of Atmospheric DMS by Oceanic Phytoplankton

Dimethylsulfide (DMS) is the most abundant form of volatile sulfur (S) in the ocean and is the main source of biogenic reduced S to the global atmosphere (Andreae and Crutzen, 1997). The sea-to-air flux of S due to DMS is currently estimated to be in the range (15-33) Tg S yr-1, constituting about 40 of the total atmospheric sulfate burden (Chin and Jacob, 1996). At the hemispheric scale (Gondwe et al., 2003) estimate that seawater DMS contributes 43 of the mean annual column burden of...

Sediment Trap

Since 1986, mark 6 and mark 7 sediment traps (Honjo and Doherty, 1988) have been deployed at water depths of approximately 3,000 m in the WAST (15 310N 68 430E Fig. 1 Table 1). Sampling intervals were set between 12 and 26 days. Prior to the deployment, the sampling cups were filled with sea water collected at the mooring depth and enriched with sodium chloride (35 gl-1) and mercury (II) chloride (3.3gl 1) to prevent degradation of trapped material (Lee et al., 1992). After recovery, the...

Soil CO2 Efflux and Remotely Sensed Surface Temperature

As described in the previous section, CO2 efflux from the soil surface has been expressed as a function of soil temperature, soil moisture, or air temperature (Grant and Rochette, 1994 Maisongrande et al., 1995 Nakadai et al., 1996). Nevertheless, since the activity of soil microorganisms is related to temperature, water, oxygen, and organic matter in the soil (Paul and Clark, 1989), it may be related to remotely sensed data in the optical, thermal, or microwave domains via information on the...

Study Sites Tropical Northwestern Pacific

The main area sampled for corals in the present study was the tropical northwestern Pacific, where published coral records are still rare compared with other areas in the tropics and subtropics (Fig. 1 Table 1). The study area covers a relatively wide range of latitude, from Pohnpei Island (7 N) in the equatorial Pacific to Ishigaki Island (24 N) in the Kuroshio Current region of the northwestern Pacific. The western equatorial Pacific is one of the hottest and wettest tropical ocean regions on...

Deposition of Aeolian Dust on the Ocean by the Atmosphere

Aeolian dust deposition over the oceans provides a biogeochemical link between climate change and terrestrial and marine ecosystems (Ridgwell, 2002). A major natural source of new iron to open ocean surface waters is continentally derived aeolian dust, which supplies about three times the Figure 7 Contemporary annual mean dust deposition rate (Ginoux et al., 2001 (For colour version, see Colour Plate Section)). Figure 7 Contemporary annual mean dust deposition rate (Ginoux et al., 2001 (For...

Comparisons with Other Results from The Northern Indian Ocean

Since it is generally assumed that there are problems with the trapping efficiency at water depths of approximately < 1,200 m (Scholten et al., 2005 Yu et al., 2001), sediment trap results obtained from shallower water depths were excluded from the following discussion. A comparison of sediment trap results obtained from the northern Indian Ocean shows the highest annual mean POC PIC ratio in the northern Bay of Bengal (1.75 Fig. 5). Within the Bay of Bengal, the POC PIC ratios decrease from...

Results and Discussion

The first set of sediment trap data obtained from the Arabian Sea, covering the years 1986 and 1987, showed a strong monsoon-driven seasonality with enhanced fluxes during the NE and SW monsoon (Nair et al., 1989). The 10 years' records on deep ocean fluxes generated subsequently have further confirmed the strong monsoon-driven seasonality (Fig. 2a). In order to produce an average record covering the annual cycle, the time-series data have been converted into bi-weekly means (Fig. 2b). It may...

Chemical Analysis

Total carbon and nitrogen were determined with a Carlo Erba Nitrogen Analyzer 1500 that measures CO2 and N2 in a constant helium flow with a thermal conductivity detector after a catalytic high-temperature combustion of the sample. The reproducibility of the determined total carbon and nitrogen concentration is 70.05 and 7 0.02 , respectively. Carbonate carbon concentration was derived from the conductivity change of a sodium hydroxide solution while injecting CO2 released from the acid-treated...

Ocean Biotic Feedbacks with Centennial Climate Change

Our ability to predict the impacts of global warming is limited by a number of key uncertainties, significant among which is the role of biotic feedbacks (IPCC, 2001). The response of biota in the surface ocean is particularly pertinent and still not well understood. However, the potential for multiple feedbacks between climate, ocean circulation and mixing, and photosyn-thetic primary production has been manifestly evident for some time (Falkowski et al., 2000 Gildor and Follows, 2002)....

Absorption of Radiation by Phytoplankton in the Upper Ocean

The effect of the absorption of solar energy by phytoplankton on upper-ocean thermal properties has been the subject of research for the past 20 years. While absorption of solar energy is dominated by absorption from seawater itself in many open ocean regions, the variability in the absorption and distribution of solar energy into the upper layers of the open ocean is controlled primarily by phytoplankton pigment concentrations (Platt, 1969 Smith and Baker, 1978). Lewis et al. (1983) were the...

Observed Transports through Major Straits of the Indonesian Throughflow

Large-scale observation-based studies (including inverse solutions) reveal significant Pacific export of mass, heat, and freshwater into the Indian Ocean (Piola and Gordon, 1984, 1986 Toole and Raymer, 1985 Wijffels et al., 1992 Toole and Warren, 1993 MacDonald and Wunsch, 1996 Ganachaud et al., 2000 Ganachaud and Wunsch, 2000). The uncertainty in the size of such a warm, fresh throughflow is the dominant source of error in analyses of the basin-wide budgets of heat and freshwater for the...

Introduction

Earth environmental problems involve feedbacks between the ecosystem and the climate. Concerning global warming, one may assume that potential feedbacks between marine ecosystem and physical processes will increase or decrease the concentration of carbon dioxide in the atmosphere than the sum of the component systems themselves. Because of the complexity of the earth environmental problems in terms of scales in time and space as well as its interconnectivity between multidisciplines in...

Development and Problems Associated with Coral Paleo Temperature Proxies

The oxygen isotopic (S18O) and strontium calcium (Sr Ca) ratios of massive coral skeletons have been widely used as proxies for past changes in SST of the tropical and subtropical oceans, because both the geochemical parameters are believed to depend on the temperature of the ambient seawater. The temperature dependency of the oxygen isotopic composition in inorganically precipitated carbonates was established by Urey (1947), but it was realized early on that the 818O of biogenic carbonates...

Estimating NPP at an Ecosystem Scale based on fAPAR from Remotely Sensed Information A Case Study

A comparative study on the relationship between the fAPAR of various plant canopies and seven vegetation indices was conducted based on airborne remote sensing data Inoue et al., 2001 . During this experiment, well-calibrated airborne optical measurements at fine spatial resolution were obtained simultaneously with ground-based hyperspectral and detailed plant measurements. This may be a useful case study that investigates the realistic relationship between vegetation indices and fAPAR, since...