A study on biological Co<sub>2</sub> fixation in the sea on the earth

A study on biological Co₂ fixation in the sea on the earth

Shintaor Goto
Kanazawa Institute of Technology, Japan

Shunji Murai
Institute of Industrial Science University of Tokyo, Japan

Abstract
This study deals with the role of satellite Remote Sensing for monitoring global environment, and the analysis the places of the Co₂ fixation in the sea. The chlorophyll distribution produced from NIMBUS/CZCS data was used for estimation of the total capacity of Co₂ fixation in the sea area. It is the first trial to estimate the ability of Co₂ fixation as the result of human activity using satellite data.

Introduction
From the statistics of fossil fuel consumption from Rotty & Marland (1986) we know that its consumption has increased from the middle of the last century to the present with about 3% annually with the present value of about 5.6 Gtc/year. On the other hand the atmospheric Co₂ concentration is 2.7Gtc/year. But the sink of the other Co₂ concentration is not known, it is called as a problem of missing sink.

May proposal to control global worming locally by fixing Co₂ concentration is presented. But the total balance of Co₂ in not cleared now. Especially the capacity of Co₂ fixation in the sea is estimated by the in situ observation data in these 30 years. So, we can't estimate the future capacity of Co₂ fixation by these data used now.

In this study, the new model to estimate the capacity of biological Co₂ fixation in the sea area using NIMBUS7/CZCS data is yield. After that the result from above is checked to the result of other studies.

Method
The data used in this study is NIMBUS/CZCS-level 3 (monthly averaged chlorophyll density), provided from NASA (Feldman et al., (1989)). Chlorophyll density is estimated by Gordon's algorithm (Gordon and Morel (1983)).

The calculation process of the capacity of Co₂ fixation in the sea is shown in Fig. 1.

The capacity of biological Co₂ fixation in the sea is estimated by net primary productivity of plankton. The process to estimate the distribution of plankton is shown in Fig. 2.

The chlorophyll distribution from Nimbus7/CZCS by Gordon's algorithm (See Fig. 3) is not effective in the region where aerosol density is high such as the region near Japan. But eh value is relatively effective in the small blocks such as each sea region.

Fig 1 Flow chart of estimation of Co₂ fixation capacity.

Fig. 2 Flowchart to produce plankton map

Fig. 3. Chlorophyll distribution by Gordon's algorith
To estimate the primary from the chlorophyll density the correlation between chlorophyll density and primary productivity. But there is only one correlation made by Epply et al (1985) in near south and north America continent. Fig. 4 shows the relation between primary productivity : p (mgCm-2d-1) and chlorophyll density Ck : (mgm-3). And the correlation is as follows ;

Log (p) = 3 + 0.5log (Ck)………………………………1)

In this study, firstly, Epply's correlation between density and net primary productivity is corrected by the observational data of primary productivity by Ryther (1963) and Koblentz-Minishke et al (1970). Table 1 shows the corrected correlation in each sea region where the in situ observation data exist. Secondly, using the new correlation, the primary productivity in each mesh is yield, and after summing up the capacity of Co₂ fixation in the sea is yield.

Table 1 Correlation primary productivity (p: mgCm-2s-1) vs. chlorophyll density (Ck: mgm-3) in each sea area.

Result
Table 2 shows the capacity of COs fixation in each sea region where Epply's correlation inc corrected. From this table the total capacity of Co₂ fixation fro original correlated is three times the value of corrected correlation. The capacity of Co₂ fixation in the sea is 31.1 GtC/year. Table 2 shows the result of comparison with the result from observational data.

Through the process above the primary productivity in the sea is calculated. Fig. 5 shows the distribution of the primary productivity in this study and Fig. 6 shows the result by Koblentz-Minshke et al. (1970)for comparison. These two result is similar except for the value in the North Atlantic Ocean. In this region the primary productivity is very high in this study. And the other problem in this study is the discontinuity of the primary productivity in each sea region.

Table 2 : PP : Primary Productivity (Gtc/year) from new correlation vs. Epply's original correlation.

Table 3 Comparison the capacity of Co₂ fixation (Gtc/year) in this study with the observational data in the sea.

Conclusion
The following conclusions were obtained. Using the chlorophyll density map by Nimbus7/CZCS, capacity of biological Co₂ fixation was estimated and it agreed with the studies before. Ti shows the potential availability of using satellite data for estimation of Co₂ fixation of changing global environment. The father research will pay attention to checking the distribution locally and to removing the discontinuity of primary productivity.

References

Box, E, 1975. Quantitative Evaluation of Global Primary Productivity Models Generated by Computers, Primary Productivity of the Biosphere (ed. Lieth, H and Whittaker, H.), Springer - Verlag New York Inc., pp265-283.0
Epply, R.W. Stewart, E. Abbot.M.R. and Heyman, U., 1985. Estimating ocean primary production from satellite chlorophyll, introduction to regional differences and statistics for the Southern California
Bight, Journal of Plankton Research, Vol. 7, no. 1 pp57-70.
McClain, J. Erold, N. Mayanrad, D. Endres, R. Evans, J. Brown, S. Walsh, M. Carle and G. Podestra, 1989. Ocean color : Availability of the global data set.
Gordon.H.R. and A.Y. Morel, 1983. Remote Assessment of Ocean color for Interpretation of satellite visible imagery, Springer - Verlag, New York.
Koblentz-Minshike, O.J., V.V. Volkovinsky, and J.C. Kabanova, 1970. Plankton primary production of the world ocean in scientific exploration of the southern pacific, edited by W.S. Wooster, National Academy of Science, Washington D.C, pp 183-193.
Rotty R.M. and Marland G., 1986. fossil fuel combustion : recent amounts, patterns and trends of Co₂. In; the changing carbon cycle: A global analysis (eds Trabalka J & Reichele D). Springer Berlin Heidelberg, New York, pp 484-500.
Ryther, J.H., 1963. The seas.11.(ed. Hill M.N), Interscience Publ., pp 347-380.
Shintaro Goto, Shunji Murai, Yoshiati Honda and Kengo Asakura, 1992.A study on the relationships between human activities and biosphere using satellite data, proc. of XVII ISPRS Congress, Washington D.C (in printing)