Biogeochemical Provinces Research Articles

Comparative analysis of bacterioplankton and phytoplankton in three ecological provinces of the northern South China Sea

The association between heterotrophic bacterioplankton and phytoplankton was exam- ined in the northern region of the South China Sea where 3 marine biogeochemical provinces adjoin. The relationship between bacterial abundance and total chlorophyll a concentration was significant in the oceanic Archipelagic Deep Basin Province and in the China Sea Coastal Province, but not so in the Beibu Gulf (Sunda-Arafura Shelves Province). The importance of different phytoplankton groups (netplankton, nanoplankton and picoplankton, Synechococcus spp., Prochlorococcus spp. and pico- eukaryotes) to bacteria was examined by multiple linear regression analysis. We found that bottom- up control on bacteria depended strongly on the picoplankton size class of the phytoplankton, and particularly on the picocyanobacteria Synechococcus spp. Possible carbon transfer mechanisms suggest a plausible basis for the linkage of Synechococcus spp. to bacteria.

Macroecological limits of heterotrophic bacterial abundance in the ocean

The global association between heterotrophic bacteria and phytoplankton in the open ocean was examined to identify the macroecological limits of bacterial abundance. A consolidated dataset was constructed using 13,973 paired measurements of bacterial abundance and chlorophyll concentration from 15 years of observation in various biogeochemical provinces covering the Atlantic, Pacific, Arctic and Antarctic Oceans as well as the Arabian Sea. The bivariate relationship between bacteria and chlorophyll is a filled polygon whose upper boundary undergoes a change in slope from positive to negative at about 1 mgChl m−3, suggesting a transition from bottom-up to top-down control of bacteria along a resource supply gradient. The upper limit of bacterial abundance in the ocean is everywhere set by phytoplankton, but the limit is not realized in productive waters because of mortality losses. A carrying capacity of about 7 trillion bacteria for 1 mg of chlorophyll is indicated by empirical observations, consistent with theoretical considerations and predictions from food web modelling.

Macroecological limits of heterotrophic bacterial abundance in the ocean

The global association between heterotrophic bacteria and phytoplankton in the open ocean was examined to identify the macroecological limits of bacterial abundance. A consolidated dataset was constructed using 13,973 paired measurements of bacterial abundance and chlorophyll concentration from 15 years of observation in various biogeochemical provinces covering the Atlantic, Pacific, Arctic and Antarctic Oceans as well as the Arabian Sea. The bivariate relationship between bacteria and chlorophyll is a filled polygon whose upper boundary undergoes a change in slope from positive to negative at about 1mgChlm−3, suggesting a transition from bottom-up to top-down control of bacteria along a resource supply gradient. The upper limit of bacterial abundance in the ocean is everywhere set by phytoplankton, but the limit is not realized in productive waters because of mortality losses. A carrying capacity of about 7 trillion bacteria for 1mg of chlorophyll is indicated by empirical observations, consistent with theoretical considerations and predictions from food web modelling.

Mapping global fisheries: sharpening our focus

AbstractMapping global landings is an important prerequisite for examining causal relationships between fishing and ecological change. Landing statistics, typically provided with poor spatial precision, can be disaggregated into a grid system of spatial cells (30 min ×30 min) using a rule‐based approach and ancillary data about distributions of fished taxa and fishing access of reporting countries. Presentation of time series catch composition is then possible for many types of marine areas including biogeochemical provinces, large marine ecosystems and exclusive economic zones.

Aquatic ecosystems: effects of solar ultraviolet radiation and interactions with other climatic change factors.

Aquatic ecosystems are a key component of the Earth's biosphere. A large number of studies document substantial impact of solar UV radiation on individual species, yet considerable uncertainty remains with respect to assessing impacts on ecosystems. Several studies indicate that the impact of increased UV radiation appears relatively low when considering overall ecosystem response, while, in contrast, effects on individual species show considerable responses. Ecosystem response to climate variability incorporates both synergistic and antagonistic processes with respect to UV-related effects, significantly complicating understanding and prediction at the ecosystem level. The impact of climate variability on UV-related effects often becomes manifest via indirect effects such as reduction in sea ice, changes in water column bio-optical characteristics, changes in cloud cover and shifts in oceanographic biogeochemical provinces.

Influence of phytoplankton taxonomic profile on the distribution of dimethylsulfide and dimethylsulfoniopropionate in the northwest Atlantic

Distributions of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were surveyed in surface waters of the NW Atlantic in May 1998, a few weeks after the spring bloom. A tri- angular transect extending from Nova Scotia to Bermuda and northeast toward Newfoundland encompassed 4 major oceanic biogeochemical provinces: Northwest Atlantic Continental Shelves (NWCS), Gulf Stream (GFST), North Atlantic Subtropical Gyre (NAST) and the North Atlantic Drift (NADR). Surface concentrations of DMS and DMSP were highest in the NADR, with peaks up to 8.9 nM DMS, 44.1 nM dissolved DMSP (DMSPd) and 240 nM particulate DMSP (DMSPp). The phyto- plankton assemblage throughout the study area was dominated by dinoflagellates and prymnesio- phytes. Statistically significant correlations were observed between the abundance of dinoflagellates and prymnesiophytes and the concentrations of DMS and DMSP along the transect. Size-fractionation of DMSPp revealed the 2 to 11 µm fraction to be the most important contributor to total DMSP (mean 72%, range 27% to 91% of total). In the region of the highest DMS(P) concentrations, the phyto- plankton assemblage was dominated by prymnesiophytes and dinoflagellates, with Chrysochro- mulina spp. and Gyrodinium flagellare being the most abundant. The abundance of these taxa showed a marked correlation with total DMSPp and with the 2 to 11 µm size fraction of DMSP in which these cells are found. This plankton assemblage was observed both early and late in the transect, which may indicate that it is a persistent feature along the northern side of the Gulf Stream at this time of year. Sea-air flux of DMS was calculated based on 2 different models. The results showed peaks in flux corresponding to the peaks in DMS concentration in surface water. Pooling and averaging the values for each biogeochemical province reveals DMS concentrations lower than the average values of an existing global DMS database for the same regions and times.

Basin-scale variability in plankton biomass and community metabolism in the sub-tropical North Atlantic Ocean

Abstract Three trans-Atlantic oceanographic surveys (Nova Scotia to Canary Islands) were carried out during fall 1992 and spring 1993 to describe the large-scale variability in hydrographic, chemical and biological properties of the upper water column of the subtropical gyre and adjacent waters. Significant spatial and temporal variability characterized a number of the biological pools and rate processes whereas others were relatively invariant. Systematic patterns were observed in the zonal distribution of some properties. Most notable were increases (eastward) in mixed-layer temperature and salinity, depths of the nitracline and chlorophyll- a maximum, regenerated production (NH 4 uptake) and bacterial production. Dissolved inorganic carbon (DIC) concentrations, phytoplankton biomass, mesozooplankton biomass and new production (NO 3 uptake) decreased (eastward). Bacterial biomass, primary production, and community respiration exhibited no discernible zonal distribution patterns. Seasonal variability was most evident in hydrography (cooler/fresher mixed-layer in spring), and chemistry (mixed-layer DIC concentration higher and nitracline shallower in spring) although primary production and bacterial production were significantly higher in spring than in fall. In general, seasonal variability was greater in the west than in the east; seasonality in most properties was absent west of Canary Islands (∼20°W). The distribution of autotrophs could be reasonably well explained by hydrography and nutrient structure, independent of location or season. Processes underlying the distribution of the microheterophs, however, were less clear. Heterotrophic biomass and metabolism was less variable than autotrophs and appeared to dominate the upper ocean carbon balance of the subtropical North Atlantic in both fall and spring. Geographical patterns in distribution are considered in the light of recent efforts to partition the ocean into distinct “biogeochemical provinces”.

The role of mesoscale variability on plankton dynamics in the North Atlantic

The intensive field observational phase of JGOFS in the North Atlantic Ocean has shown the importance of oceanic mesoscale variability on biogeochemical cycles and on the strength of the ocean biological pump. Mesoscale physical dynamics govern the major time/space scales of bulk biological variability (biomass, production and export). Mesoscale eddies seem to have a strong impact on the ecosystem structure and functioning, but observational evidence is rather limited. For the signature of the mesoscale features to exist in the ecosystem, the comparison of temporal scales of formation and evolution of mesoscale features and reaction of the ecosystem is a key factor. Biological patterns are driven by active changes in biological source and sink terms rather than simply by passive turbulent mixing. A first modelling assessment of the regional balances between horizontal and vertical eddy-induced nutrient supplies in the euphotic zone shows that the horizontal transport predominates over the vertical route in the subtropical gyre, whereas the reverse holds true for the other biogeochemical provinces of the North Atlantic. Presently, despite some difference in numbers, the net impact of modelled eddies yields an enhancement of the biological productivity in most provinces of the North Atlantic Ocean. Key issues remaining include variation on the mesoscale of subsurface particle and dissolved organic matter remineralization, improved knowledge of the ecological response to patterns of variability, synopticity in mesoscale surveys along with refining measures of biogeochemical time/space variability. Eventual success of assimilation of in situ and satellite data, still in its infancy in coupled physical/biogeochemical models, will be crucial to achieve JGOFS synthesis in answering which data are most informative, standing stocks or rates, and which ones are relevant. Depending on which end of the spectrum quantification of the effect of mesoscale features on production and community structure is required, complementary strategies are offered. Either one may choose to increase resolution of models up to the very fine mesoscale features scale (a few kms) for the high end, or to include a parametric representation of eddies for the low end.

Organic carbon fluxes in the Atlantic and the Southern Ocean: relationship to primary production compiled from satellite radiometer data

Fluxes of organic carbon normalised to a depth of 1000 m from 18 sites in the Atlantic and the Southern Ocean are presented, comprising nine biogeochemical provinces as defined by Longhurst et al. (1995. Journal of Plankton Research 17, 1245–1271). For comparison with primary production, we used a recent compilation of primary production values derived from CZCS data (Antoine et al., 1996. Global Biogeochemical Cycles 10, 57–69). In most cases, the seasonal patterns stood reasonably well in accordance with the carbon fluxes. Particularly, organic carbon flux records from two coastal sites off northwest and southwest Africa displayed a more distinct correlation to the primary production in sectors (1×1°) which are situated closer to the coastal environments. This was primarily caused by large upwelling filaments streaming far offshore, resulting in a cross-shelf carbon transport. With respect to primary production, organic carbon export to a water depth of 1000 m, and the fraction of primary production exported to a depth of 1000 m (export fraction=EF 1000), we were able to distinguish between: (1) the coastal environments with highest values (EF 1000=1.75–2.0%), (2) the eastern equatorial upwelling area with moderately high values (EF 1000=0.8–1.1%), (3) and the subtropical oligotrophic gyres that yielded lowest values (EF 1000=0.6%). Carbon export in the Southern Ocean was low to moderate, and the EF 1000 value seems to be quite low in general. Annual organic carbon fluxes were proportional to primary production, and the export fraction EF 1000 increased with primary production up to 350 gC m −2 yr −1 . Latitudinal variations in primary production were reflected in the carbon flux pattern. A high temporal variability of primary production rates and a pronounced seasonality of carbon export were observed in the polar environments, in particular in coastal domains, although primary production (according to Antoine et al., 1996. Global Biogeochemical Cycles 10, 57–69), carbon fluxes, and the export fraction remained at low.

Sensitivity of ecosystem parameters to simulated satellite ocean color data using a coupled physical-biological model of the North Atlantic

A means of assimilating simulated satellite ocean color data with a coupled physical-biological model of the North Atlantic Ocean is implemented, allowing the relative sensitivities of different biological parameters to those data to be investigated. The model consists of an eddy-permitting general circulation model derived from the WOCE Community Modeling Effort and a nitrogen-based, four-compartment NPZD marine ecosystem model. Many of the parameters in marine ecosystem models are poorly known and via assimilation, we hope to better constrain their values. The control parameters chosen for the variational assimilation are the model parameters involved in parameterizations of recycling as these are the most poorly known. Simulated observations are taken while following several floats seeded in varying dynamical biogeochemical provinces of the North Atlantic model domain over a six-month period. Twin experimental results show that, for the given functional forms of growth, mortality and grazing, the following parameters can be successfully recovered from simulated satellite ocean color data: nitrate and detrital recycling parameters in the trade wind domain, zooplankton parameters at higher latitudes (westerly wind and polar domains), and the phytoplankton mortality rate in all regions. By simultaneously assimilating ocean color data in different biological provinces, it becomes possible to successfully constrain all ecosystem parameters at once.

Nitrogen assimilation and the f-ratio in the northwestern Indian Ocean during an intermonsoon period

Rates of nitrogen assimilation by phytoplankton were measured at 13 stations along a transect in the northwestern Indian Ocean, from the Gulf of Oman, southwards to approximately 8°N, during November and December 1994. Nitrate (NO 3), ammonium (NH 4) and urea assimilation were measured using simulated in situ 15N incubation techniques. These measurements were supported by simultaneous rate measurements of primary production using 14C incubation techniques and detailed vertical distributions of temperature and chlorophyll concentrations. Euphotic zone integrated nitrogen assimilation rates varied between 1.1 and 23.6 mmol N m -2 day -1, with generally higher rates occurring at the northern and southern ends of the transect. At the majority of stations ammonium was the preferred nitrogen substrate assimilated; the average integrated assimilation rate of ammonium being 3.7 mmol N m -2 day -1 compared to 1.6 and 1.8 mmol N m -2 day -1 for urea and nitrate respectively. This general preference is reflected in the low f-ratios, which were ⩽0.52 for all stations and in the relative preference indices (RPI) values which were consistently >1 for ammonium and <1 for nitrate. A further examination of the data has lead to an apparent partitioning of the northwestern Indian Ocean into 2 regions; a region north of 17°30′N and a region south of this, to about 8°N. This division is based on: (i) the relationship between the f-ratio and ambient nitrate levels; (ii) nitrogen assimilation and primary production and (iii) the biomass distribution. It is suggested that this partitioning should be investigated further with the development of biogeochemical provinces in mind and the estimation of f-ratios on much larger, horizontal scales.

Depth-integrated primary production in the eastern tropical and subtropical North Atlantic basin from ocean colour imagery

Existing satellite numerical models and data interpolation methods were used to evaluate the scales of variation in the vertical distribution of the phytoplankton biomass and the daily rate of primary production within the subtropical and tropical NE Atlantic Ocean (5-40 N; 6-30 W). The choice of this area was dictated principally by its economical importance, as it represents a large fishing ground due to upwelling activities along the coast of Morocco and Mauritania. After geographical partition of the area of study into 'bio-geochemical provinces' based on bathymetry and surface circulation, up to 300 satellite scenes obtained from the defunct Coastal Zone Color Scanner (CZCS) and covering the full year 1983 were processed into maps of surface chlorophyll and were further analysed into integrated primary production. Analyses of satellite data included a specific method to account for the sensitivity loss of the sensor during the studied period. The results of the productivity model are presented in terms of seasonal variations in the daily and annual photosynthetic carbon production in the various provinces and their contribution to the productivity of the overall study area. A total of 0.82 GtC y-1 was computed for the subtropical and tropical NE Atlantic. One third of this is produced within the coastal zone although it accounts for only 14% of the total area.

Photosynthetic parameters of phytoplankton from 50°N to 50°S in the Atlantic Ocean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 176:191-203 (1999) - doi:10.3354/meps176191 Photosynthetic parameters of phytoplankton from 50°N to 50°S in the Atlantic Ocean Emilio Marañón*, Patrick M. Holligan School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, Southampton SO14 3ZH, United Kingdom *Present address: Departamento de Ecología y Biología Animal, Campus Lagoas-Marcosende, Universidad de Vigo, E-36200 Vigo, Spain. E-mail: em@uvigo.es ABSTRACT: We conducted 150 photosynthesis-irradiance (P-E) experiments along 2 Atlantic meridional transects from 50°N to 50°S in April-May and October-November 1996. The latitudinal and vertical distributions of the maximum chlorophyll a-normalized rate of photosynthesis (PBm) and the initial slope of the P-E curve (αB) were examined in relation to the variations in relevant physical, chemical and biological variables. PBm ranged from <1 mgC mgchl-1 h-1 in the central oligotrophic gyres to >10 mgC mgchl-1 h-1 in temperate regions and the upwelling area off Mauritania. The dynamic range of the observed variations in the P-E parameters was 3 to 4 times higher than assumed in productivity models that divide the ocean into biogeochemical provinces. Variability in the physiological parameters of phytoplankton was as high as that of chlorophyll concentration. We obtained a model of multiple linear regression to calculate integrated primary productivity from data of surface temperature, chlorophyll a and PBm. Changes in PBm accounted for 30% of the total variability in productivity, whereas variations in chlorophyll a explained only 5%, which indicates that phytoplankton photophysiology is more relevant than biomass in the control of primary productivity. We found a significant, negative correlation between the latitudinal changes in PBm and those in the depth of the nitracline, suggesting an important role for the nutrient supply from below the thermocline in the regulation of photosynthetic efficiency over large spatial scales. A large degree of temporal variability was observed in the subtropical gyres: PBm and αB varied by a factor of 3 between the 2 cruises, whereas phytoplankton biomass remained constant. The differences in the photosynthetic parameters between seasons were larger than between biogeochemical provinces. We emphasize the need to include nutrient-driven changes of phytoplankton photophysiology in models of primary productivity. KEY WORDS: P-E relationships · Photosynthesis · Phytoplankton · Nutrients · Temporal variability · Atlantic Ocean Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 176. Publication date: January 18, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Regional distribution of diffusive phosphate and silicate fluxes through the sediment–water interface: the eastern South Atlantic

From pore water concentration profiles and calculations of the corresponding diffusive fluxes, regional distribution patterns of benthic phosphate and silicate release rates were studied in the eastern South Atlantic. Comparisons among nutrient recycling rates and their control parameters, such as primary production and water depth, give evidence for significant differences in the benthic environment. Varying influences of these control parameters to decomposition and dissolution within surficial sediments are used to characterize single biogeochemical provinces within the study area. Maximum pore water concentrations (>0.4 mmol/l H 4SiO 4 and >10 μmol/l) and diffusive release rates (>400 mmol/m 2 a H 4SiO 4 and >4 mmol/m 2 a PO 3- 4 were observed in sediments off Namibia. Compared to benthic recycling rates in this upwelling regime, those in other regions of intensified primary production seem to be minor. While early diagenetic phosphate release is related to water depth and organic carbon flux to the sea floor, the benthic silicate flux is influenced by the general primary production and other parameters, such as the chemistry and rain rate of biogenic opal. These, again, depend on the oceanographic situation. With respect to the oceanic nutrient cycling and the role of marine deposits as geochemical sink, the presented data confirm the importance of degradation and dissolution processes at the sediment–water interface. At approximately 6.2×10 11 mol/a the benthic silicate re-flux is about three times greater than the dissolved silicate discharge of the Zaire River, which is the dominant terrestrial source in this region.

Seasonal variations in physiological parameters of phytoplankton across the North Atlantic

Variations in the shapes of the action and absorption spectra, and the physiological parameters of phytoplankton (a, the biomass (B)-specific initial slope of the photosynthesis-irradi- ance curve; PS,, the plateau of the curve; m, the maximum quantum yield of photosynthesis), were studied. Data were collected in the North Atlantic in five biogeochemical provinces for two seasons: in fall of 1992 and spring of 1993. Further, some nine independent variables were tested for their ability to predict the physiological parameters, using linear regression analyses. It was found that the parameters were more variable between seasons than between provinces, although the differences in the spectral shapes between provinces were significant. It was also shown that several independent variables (alone or in combination) were able to predict a significant fraction of the total variance in the parameters. However, the correlation between variables and parameters differed unsystemati- cally both between provinces and seasons. The results suggest that predicting a parameter from an independent variable would have to be carried out at a province level: the relationship changed or disappeared when data from two or more provinces were pooled.

Pelagic biogeography of the South Atlantic Ocean

The biogeography of the South Atlantic was investigated using presence/absence data for euphausiids. Records were taken from recent and historic, as well as published and unpublished data sets. The resulting biogeography is the most complete to date and can be usefully compared with the biogeochemical provinces for the region. A total of six biogeographic provinces were identified from similarity analyses of the 246 five-degree grid squares. These correspond to Antarctic, sub-Antarctic, cold temperate, warm temperate (subtropical) and tropical waters, as well as the Agulhas Current. Congruence with the biogeochemistry of the region is good in the south and emphasises the important determinate role of temperature. However, the biogeography fails to identify coastal and tropical biogeochemical provinces. This can be attributed to the fact that while adjoining areas may share many species in common, their assemblages differ in their quantitative composition. This serves to emphasise differences in provincial functioning.

Particle flux in deep seas: regional characteristics and temporal variability

Particle flux data have been collated from the literature representing most areas of the open ocean to determine regional trends in deep water flux and its seasonal variability. Organic carbon flux data normalised to a depth of 2000 m exhibits a range of an order of magnitude in areas outside the polar domains (0.38 to 4.2 g/m2/y). In polar regions the range is wider (0.01–5.9 g/m2/y). Latitudinal trends are not apparent for most components of the flux although calcite flux exhibits a poleward decrease. Limited data from polar regions show fluxes of opaline silica not significantly higher than elsewhere.The variability of flux over annual cycles was calculated and expressed as a Flux Stability Index (FSI) and the relationship between this and vertical flux of material examined. Somewhat surprisingly there is no significant relationship between FSI and fluxes of dry mass, organic carbon, inorganic carbon or opaline silica. At each site, net annual primary production was determined using published satellite derived estimates. There is a negative but weak relationship between FSI and the proportion of primary production exported to 2000 m (e2000 ratio). The most variable of the non-polar environments export to 2000 m about twice as much of the primary production as the most stable ones. Polar environments have very low e2000 ratios with no apparent relationship to FSI.At primary production levels below 200 g C/m2/y there is a positive correlation between production and organic carbon flux at 2000 m but above this level, flux remains constant at about 3.5g C/m2/y. A curve derived to describe this relationship was applied to estimates of annual primary production in each of 34 of the open ocean biogeochemical provinces proposed by Longhurst et al. (1995). Globally, open ocean flux of organic carbon at 2000 m is 0.34 Gt/yr which is 1% of the total net primary production in these regions. This flux is nearly equally divided between the Atlantic, Pacific and Southern Oceans. The Indian and Arctic oceans between them only contribute 5% to the total.The eight planktonic climatological categories proposed by Longhurst (1995) provide a most useful means of examining the data on flux and its variability. A characteristic level of FSI was found in each category with highest levels in the tropics and lowest levels in the Antarctic. There is also a characteristic level of export ratio in each category with the highest in monsoonal environments (1.7%) and the lowest in Antarctica (0.1%).

Seasonal variability of light availability and utilization in the Sargasso Sea

A 2 year time series of optical, biogeochemical, and physical parameters, taken near the island of Bermuda, is used to evaluate the sources of temporal variability in light availability and utilization in the Sargasso Sea. Integrated assessments of light availability are made by examining the depth of constant percent incident photosynthetically available radiation (%PAR) isolumes. To first order, changes in the depth of %PAR isolumes were caused by physical processes: deep convective mixing in the winter which led to the spring bloom and concurrent shallowing of %PAR depths and the occurrence of anomalous thermohaline water masses during the summer and fall seasons. Spectral light availability variations are assessed using determinations of diffuse attenuation coefficient spectra which illustrate a significant seasonal cycle in colored detrital paniculate and/or dissolved materials that is unrelated to changes in chlorophyll pigment concentrations. Temporal variations in the photosynthetic light utilization index Ψ are used to assess vertically integrated light utilization variations. Values of Ψ are highly variable and show no apparent seasonal pattern which indicates that Ψ is not simply a “biogeochemical constant” Determinations of in situ primary production rates and daily mean PAR fluxes are used to diagnose the relative role of light limitation in determining vertically integrated rates of primary production ∫PP. The mean depth of the light‐saturated zone (the vertical region where the daily mean PAR flux was greater than or equal to the saturation irradiance Ik) is only ∼40 m, although more than one half of ∫PP occurred within this zone. Production model results illustrate that accurate predictions of ∫PP are dependent upon rates of light‐saturated production rather than upon indices of light limitation. It seems unlikely that significant improvements in simple primary production models will come from the partitioning of the Earth's seas into biogeochemical provinces.

An estimate of global primary production in the ocean from satellite radiometer data

An estimate of global net primary production in the ocean has been computed from the monthly mean near-surface chlorophyll fields for 1979–1986 obtained by the Nimbus 7 CZCS radiometer. Our model required information about the subsurface distribution of chlorophyll, the parameters of the photosynthesis-light relationship, the sun angle and cloudiness. The computations were partitioned among 57 biogeochemical provinces that were specified from regional oceanography and by examination of the chlorophyll fields. Making different assumptions about the overestimation of chlorophyll by the CZCS in turbid coastal areas, the global net primary production from phytoplankton is given as 45–50 Gt C year−1. This may be compared with current published estimates for land plants of 45–68 Gt C year−1 and for coastal vegetation of 1.9 Gt C year−1.

Advances in medico-chemical geography in China

We have made progress in medico-chemical geography as follows: the correlative law of organism with geochemical environment; the geochemico-ecological classification of chemical elements; the types of formative cause of biogeochemical provinces in China; the parabolic correlation between contents of iodine in drinking water and prevalence rate of endemic goiter; the discover and proof of the low selenium zone in China; the successive discovery of endemic fluorosis of the types of pollution from burning coal, drinking high fluoride tea and high fluoride table salt from the year 1978; the study on chemical geography of schistosomiasis and the compilation of the Atlas of Endemic Diseases and Their Environments in the People’s Republic of China.