ISSN 1028334X, Doklady Earth Sciences, 2016, Vol. 466, Part 1, pp. 78–81. © Pleiades Publishing, Ltd., 2016. Original Russian Text © A.P. Lisitzin, A.A. Klyuvitkin, V.I. Burenkov, M.D. Kravchishina, N.V. Politova, A.N. Novigatsky, V.P. Shevchenko, T.S. Klyuvitkina, 2016, published in Doklady Akademii Nauk, 2016, Vol. 466, No. 2, pp. 221–224.
OCEANOLOGY
Distribution and Composition of Suspended Particulate Matter in the Atlantic Ocean: Direct Measurements and Satellite Data Academician A. P. Lisitzina, A. A. Klyuvitkina, V. I. Burenkova, M. D. Kravchishinaa,
N. V. Politovaa, A. N. Novigatskya, V. P. Shevchenkoa, and T. S. Klyuvitkinab Received April 9, 2015
Abstract—The main purpose of this work is to study the real distribution and spatial–temporal variations of suspended particulate matter and its main components in surface waters of the Atlantic Ocean on the basis of direct and satellite measurements for development of new and perfection of available algorithms for convert ing satellite data. The distribution fields of suspended particulate matter were calculated and plotted for the entire Atlantic Ocean. It is established that its distribution in the open ocean is subordinate to the latitudinal climatic zonality. The areas with maximum concentrations form latitudinal belts corresponding to highpro ductivity eutrophic and mesotrophic waters of the northern and southern temperate humid belts and with the equatorial humid zone. Phytoplankton, the productivity of which depends primarily on the climatic zonality, is the main producer of suspended particulate matter in the surface water layer. DOI: 10.1134/S1028334X16010116
colour scanner by standard algorithms and results of direct onboard investigation of water samples. The main purpose of this work is to study the real distribution and spatial–temporal variations of sus pended sedimentary matter and its main components in surface waters of the Atlantic Ocean on the basis of direct (field) and satellite measurements for develop ment of new and improvement of available algorithms for converting satellite data. This purpose predetermined the following tasks: targeted (using preliminary satellitebased images) sampling of suspended particulate matter (SPM) in field conditions; analytical investigation of its compo sition; selection and processing of satellitebased data for the period and area of field investigations; correla tion of direct and satellite measurements for develop ment of algorithms for calculating distribution fields of suspended particulate matter and its main compo nents; and establishment of spatial–temporal varia tions in the SPM distribution. The study of suspended particulate matter along transects across the Atlantic Ocean by direct methods was carried out in the period of 2001 to 2010 (Cruise 18 of the R/V Akademik Fedorov, Cruises 48 and 49 of the R/V Akademik Mstislav Keldysh, Cruises 11, 16, and 26 of the R/V Akademik Ioffe, Cruises 17, 19, 20, and 31 of the R/V Akademik Sergei Vavilov). Surface water samples for SPM extraction were taken with the motion of the ship several times a day during the satel lite overflight. Water was filtered through a preliminar ily weighted 47mm nuclear pore filter with pores 0.4 µm in diameter for determining the concentra
The study of the system of formation and distribu tion of suspended particulate matter (SPM) is of importance for understanding the processes of mod ern sedimentation and interpretation of biological, chemical, and geological processes occurring in the ocean. Suspended matter is the primary material for accumulation of bottom sediments, and the matter being deposited takes part in the geological evolution of the ocean [1, 2]. The main source of the sedimen tary material, so to say, the zone of the matter mobili zation, is the upper active layer of the ocean. The data on distribution of concentration and composition of the suspended material derived from satellite coastal zone color scanner are of importance. This technique allows us to monitor the surface distri bution of the suspended material not only in a single observation site, but simultaneously over the ocean surface and to study changes in concentration and composition on various scale of time. The concentra tion values of different constituents of the suspended matter (chlorophyll, suspended organic carbon, etc.), calculated on the basis of standard algorithms, are available on the NASA website (http://oceanolog. gsfc.nasa.gov). However, large differences are recorded between the data derived from satellite
a
Shirshov Institute of Oceanology, Russian Academy of Sciences, Nakhimovskii pr. 36, Moscow, 117218 Russia b Department of Geography, Moscow State University, Moscow, Russia email:
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tions and composition of suspended particulate matter and separately through Whatman GF/F fiberglass fil ters for determining the particulate organic carbon (POC) and calcium carbonate (CaCO3) contents. The main SPM components were determined in laboratories of the Institute of Oceanology: lithogenic matter (LM) on the basis of Al (LM = Al × 10) [5]; particulate organic matter: (POM) = 2POM) [6]; CaCO3 , and amorphous silica (SiO2amorph). Biogenic matter was determined as the sum of three biogenic components of suspended particulate matter, or its biogenic triad (BM = POM + CaCO3 + SiO2amorph). The Ocean Color Web system (http://ocean color.gsfc.nasa.gov) was used for collecting satellite data, which were used for calculating the chlorophyll concentrations (Chl) and the coefficient of light back scattering by suspended particulate matter (bbp). These data were processed using software of the Institute of Oceanology [7]. Development of reliable algorithms for converting satellite data into real values for different seasons and different natural zones is one of the most important tasks of our longterm investigations. The available
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Fig. 1. Correlation between bbp derived from satellite observations (m–1) and SPM concentrations determined by direct measurements (mg/L).
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Fig. 2. The typical SPM distribution in the surface water layer of the Atlantic Ocean during different seasons (spring and autumn of the Northern Hemisphere). Dots indicate sampling sites. Dashed lines show structural zones of the ocean [13]: (SPD) Subpo lar Divergence, (NPF) Northern Polar Front, (NSTC) Northern Subtropical Convergence, (NTF) Northern Tropical Front, (STF) Southern Tropical Front, (NTD) Northern Tropical Divergence, (STD) Southern Tropical Divergence, (STF) Southern Tropical Front, (SSTC) Southern Subtropical Convergence, (SAF) Subantarctic Front, (SPF) Southern Polar Front. DOKLADY EARTH SCIENCES
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Fig. 3. The zonal distribution of SPM, LM, and BM concentrations along two characteristic submeridional transects across the main natural zones of the Atlantic Ocean on the basis of field observations during autumn of the Northern Hemisphere. (1–3) Concentrations: (1) SPM, (2) LM, (3) BM.
algorithms for calculating the Chl concentrations are widely used now [8, 9], while development of algo rithms for calculating SPM concentrations is still in progress [7, 10, 11]. For each point of SPM sampling, we selected the data obtained by the MODISAqua sea color scanner. The comparison between obtained pairs of data (satellite and direct parallel measure ments in field conditions, Fig. 1) provided the ratio that was used for compiling maps of the SPM distribu tion in the surface water layer for the entire Atlantic Ocean with account for the data obtained in different expeditions (10 in total) and during different seasons in 2001–2010 (Fig. 2). The correlation of the Chl (and BM) concentrations with SiO2amorph and CaCO3 con tents is insignificant due to variations in the propor tions of carbonate and silicasecreting species in planktonic communities of different natural zones (0.54 and 0.45, respectively). A single LM ratio for the entire ocean is still unavailable because of its low con centrations (up to 10% of total suspended particulate matter). High LM concentrations were registered only in coastal areas of the ocean (up to 80%) and in areas
influenced by flows of atmospheric aerosols from arid zones of Africa (up to 20%) [2, 12]. Figure 3 presents the zonal distribution of SPM, LM, and BM concentrations along two characteristic submeridional transects across the main natural zones of the Atlantic Ocean derived from field observations during the autumn season of the Northern Hemi sphere. The analysis of data obtained in ten expeditions revealed that the SPM concentrations in the surface water layer of the Atlantic Ocean vary from trace (0.02 mg/L) to maximum values of 35.1 mg/l. Its typ ical concentrations in open areas of the ocean range from 0.1 to 0.5 mg/L. The elevated SPM concentra tors in the ocean are recorded near river mouths, in coastal areas (particularly, upwelling zones), and in marginal seas (Baltic, North, and others). Away from the shore, its concentrations decrease reflecting the circumcontinental zonality [2]. In the open ocean, the maximum concentrations of suspended particulate matter are observable in areas occupied by highproductivity eutrophic and mesotrophic waters of the northern and southern DOKLADY EARTH SCIENCES
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humid belts reflecting, thus, the latitudinal climatic zonality. In the northern and southern belts, the max imum SPM concentrations are as high as 0.7 and 0.6 mg/l, respectively. The third SPM maximum in the pelagic realm of the Atlantic Ocean corresponds to the equatorial humid belt, where its high concentrations of 0.13– 0.46 mg/l (0.27 mg/l on average) are confined to trop ical divergences. Thus, maximum concentrations of suspended par ticulate matter are characteristic of humid zones. The minimal SPM concentrations are observable in the northern and southern arid zones, which repre sent “tropical deserts” of the ocean. The SPM mini mums are confined to the Northern and Southern Atlantic tropical gyres, where its contents vary from 0.04 to 0.3 mg/l. The analysis of the SPM distribution made it possi ble to calculate and plot, for the first time, the distri bution fields of suspended particulate matter and its main components for the entire Atlantic Ocean on the basis of satellite data with their verification by direct field measurements in ten expeditions organized by Institute of Oceanology. In the open ocean, their dis tribution reflects best of all the latitudinal climatic zonality in natural processes. The areas with maxi mum SPM concentrations extend along latitudinal belts and correspond to the northern and southern temperate humid belts with highbioproductivity eutrophic and mesotrophic waters and to the equato rial humid zone. The main producer of suspended par ticulate matter in the surface water layer is represented by phytoplankton, the distribution of which in the World Ocean is characterized by zonal patterns [14]. Thus, our tenyearlong investigation has made it possible to establish the distribution of suspended par ticulate matter and chlorophyll along several meridi onal transects and to verify the satellite data, which cover the entire ocean many times. The distribution of suspended particulate matter and its biogenic compo nents (on the basis of chlorophyll) along transects may be extrapolated onto the entire pelagic zone of the ocean as well as onto shelves and drainage areas taking into consideration the circumcontinental zonality. Previously, zonal patterns in the distribution of bottom sediments were established for the Pacific and Indian oceans [1]. All these direct field and satellite observa tions cast doubt on the previous standpoint wide spread among lithologists that no zonality exists in the DOKLADY EARTH SCIENCES
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distribution and composition of suspended particulate matter in the World Ocean. ACKNOWLEDGMENTS Analysis of the material was supported by the Rus sian Science Foundation (grant no. 145000095). Interpretation of the data was supported in part by the State Scientific Program of the Institute of Oceanol ogy, Russian Academy of Sciences, for 2015–2017, theme no. 014920140026. REFERENCES 1. A. P. Lisitsyn, Processes of Oceanic Sedimentation. Lithology and Geochemistry (Nauka, Moscow, 1978) [in Russian]. 2. A. P. Lisitsyn, in World Ocean, Ed. by L. I. Lobkovskii and R. I. Nigmatulin (Nauchn. Mir, Moscow, 2014), Vol. 2, pp. 331–571 [in Russian]. 3. V. I. Burenkov, V. I. Vedernikov, S. V. Ershova, et al., Oceanology 41 (4), 461–468 (2001). 4. M. D. Kravchishina, V. I. Burenkov, O. V. Kopelevich, et al., Dokl. Earth Sci. 448 (1), 120–125 (2013). 5. J. Kuss and K. Kremling, Mar. Chem. 68, 71–86 (1999). 6. S. Krishnaswami and M. M. Sarin, Earth Planet. Sci. Lett. 32, 430–440 (1976). 7. V. I. Burenkov, A. A. Klyuvitkin, and S. V. Sheberstov, in Proc. 4th Int. Conf. on Current Problems in Optics of Natural Waters (ONW’ 2007) (Nizhny Novgorod, 2007), pp. 154–156. 8. J. E. O’Reilly, S. Maritorena, B. G. Mitchell, et al., J. Geophys. Res. 103 (C11), 24937–24953 (1998). 9. A. B. Demidov, V. I. Vedernikov, and S. V. Sheberstov, Oceanology 47 (4), 507–518 (2007). 10. V. I. Burenkov, S. V. Ershova, O. V. Kopelevich, et al., Oceanology 41 (5), 622–628 (2001). 11. A. A. Klyuvitkin, V. I. Burenkov, and S. V. Sheberstov, Priroda, No. 6, 35–39 (2009). 12. A. A. Klyuvitkin, Dokl. Earth Sci. 421 (5), 848–852 (2008). 13. V. A. Burkov, Total Circulation of the World Ocean (Gidrometeoizdat, Leningrad, 1980) [in Russian]. 14. M. E. Vinogradov, “Biological produñtivity of oceanic ecosystems,” in New Ideas in Oceanology, Vol. 1: Physics. Chemistry. Biology, Ed. by M. E. Vinogradov and S. S. Lappo (Nauka, Moscow, 2004), pp. 237–263 [in Russian].
Translated by I. Basov
