Showing papers on "Carbon cycle published in 1989"

Photochemical source of biological substrates in sea water: implications for carbon cycling

Abstract: DISSOLVED organic carbon (DOC) in sea water represents one of the largest reservoirs of carbon on the earth1. The main fraction of this DOC is generally believed to be composed of old2, biologi-cally refractory material3 such as humic substances, for which the removal mechanisms remain largely unknown. One potentially important removal process in the ocean that has not been investi-gated is the photochemical breakdown of this DOC in the photic zone to form biologically labile organic products. Here we show that biological uptake of pyruvate is highly correlated to its rate of photochemical production in sea water (r = 0.964), and that the photochemical precursor(s) of pyruvate is from the fraction of DOC having a nominal molecular weight of 500. This is the first evidence that photochemical breakdown of high-molecular-weight marine DOC, which is presumably biologically refractory, results in the production of a compound that is used by plankton as a substrate. Our results have important implications for the oceanic carbon cycle, particularly with respect to planktonic-food-web dynamics and the global carbon budget.

Pelagic-benthic coupling on the shelf of the northern Bering and Chukchi Seas. Ill Benthic food supply and carbon cycling

Abstract: Benthic carbon c y c h g in the northern Bering and Chukchi Seas was hypothesized to be regulated by variable primary production regimes in the overlying water: the highly productive (-250 to 300 g C m-2 yr-l) Bering Shelf-Anadyr Water (BSAW) and the less productive (-50 g C m-2 yr-l) Alaska Coastal Water (ACW). Sediment oxygen uptake was correlated with water column parameters and surface sediment C/N ratios characteristic of each water type. Total sediment oxygen uptake rates decreased from a mean 19.2 mm01 O2 m-2 d-' in BSAW to a mean 8.7 mm01 O2 m-' d-' in ACW. Mean benthic aerobic respiration rates significantly varied interannually in BSAW, although they were consistently 2 to 3 times greater in BSAW than in ACW within any one year, indicating that interannual variability in water column primary production may have a direct influence on the availability of organic carbon to the benthos. The explanation for higher respiration rates in the benthos beneath BSAW negates an expected reduction due to colder temperatures. A reduction in organic matter to the benthos in ACW apparently limits benthic metabolism even at higher temperatures. Macrofaunal respiration and bioturbation in high benthic biomass regions were important components in benthic carbon cycling.

C-Isotope stratigraphy, a monitor of paleoenvironmental change: A case study from the early cretaceous

Abstract: Today's disturbance of the global carbon cycle induced by anthropogenic processes has raised new interest in the history of the global carbon cycle and its relationship to climate and other geochemical cycles. Carbon-isotope stratigraphy proves to be most useful as a monitor of the history of the carbon-cycle during the last 200 million years. In the introductory paragraphs of this review the mode of functioning of the global carbon-cycle is summarized and the connection between carbon-cycle and carbon isotope geochemistry is documented. A case study on the disturbance of the global carbon cycle during the Aptian-Albian is presented. The disturbance of the carbon cycle lasting up to millions of years is recorded in the carbon-isotope stratigraphy of pelagic sediments. It is superimposed on high frequency sedimentological cycles, related to climate and oceanographic cycles of 20, 40 or 100 ky duration. The data reviewed suggest that the change in the global carbon system was linked to a global acceleration of geochemical cycles triggered by a long-term change in atmospheric CO2 controlled by the rate of sea-floor formation and by volcanic activity. Increased accumulation rates of terrestrial material and terrestrial organic matter in marine sediments may be used as an indicator of an intensified hydrological cycling resulting in higher water-discharge rates. An intensification of the Aptian-Albian water cycle is further reflected in continental sediments monitoring a period of elevated humidity. An increase in water discharge rates should have affected the transfer rate of dissolved nutrients from continents to oceans. Elevated concentrations of phosphorus may have led to an increase in Aptian-Albian oceanic productivity enhancing the transfer of marine organic matter from the oceanic into the sedimentary reservoir. Increased productivity, increased bulk sedimentation rates and poorly oxygenated deep-water led to increased preservation of marine and terrestrial organic matter in marine sediments. The accelerated output of marine organic carbon from the oceanic reservoir is ultimately registered in the positive carbon-isotope excursion of the marine carbonate carbon-isotope stratigraphy.

Modeling the geochemical carbon cycle

Abstract: The authors have modeled the slow, long-term cycle in which geochemical processes transfer carbon among land, sea, and atmosphere. The model suggests that the earth may have been warmed in the past when buildups of atmospheric carbon dioxide enhanced the greenhouse effect. The model predicts that the slow natural fluctuations of atmospheric carbon dioxide may rival or even exceed the much faster changes that arise from human activities or from the biological carbon cycle. The main purpose in modeling the geochemical carbon cycle is to expose how little is known about the rates of important global processes and how seemingly unrelated processes (such as tectonism and climate) are linked.

AMS 14C measurements of fractionated soil organic-matter - an approach to deciphering the soil carbon-cycle

Abstract: [RADIOCARBON, VOL 31, No. 3, 1989, P 644-654] AMS 14C MEASUREMENTS OF FRACTIONATED SOIL ORGANIC MATTER: AN APPROACH TO DECIPHERING THE SOIL CARBON CYCLE S E TRUMBORE Department of Geological Sciences, Columbia University and Lamont-Doherty Geological Observatory, Palisades, New York 10964 J S VOGEL and J R SOUTHON Department of Archaeology, Simon Fraser University, Burnaby, British Columbia, V5A IS6 Canada ABSTRACT. 14C measurements are reported for fractionated soil organic matter from a genetic soil sequence which was sampled several times during the period of atmospheric nuclear weapons testing. Fractionation of the soils by density followed by acid hydrolysis was successful in separating the organic matter into components with mean residence times for carbon ranging from 5 to 20 years (low density fraction) to several thousand years (residue after acid hydrolysis). Comparison of the infiltration of bomb 14C into the vertical soil profile with the distribution of 137Cs, gives clues as to the mechanism (most probably dissolved transport) for importing carbon into deeper soil layers. INTRODUCTION An estimated 1300 to 1500 x 1015g of carbon is sequestered as organic matter in soils (Schlesinger, 1977; Post et a1, 1982). This is roughly twice the amount of carbon present either in the atmosphere as CO2 or as land bios- phere (Whittaker & Likens, 1973), and 200 times the amount of CO2 added to the atmosphere annually by fossil fuel burning (Rotty, 1977). To under- stand the evolution of soil humic material, and to better incorporate the organic matter in soils into models of the global carbon cycle, it is necessary to quantify the relative amounts and turnover times of labile and refractory carbon in soil organic matter, and how these vary with parameters such as climate, vegetation and geography. 14C dating of bulk soil organic matter gives 14 C ages which range from over-modern (containing 14C produced by atmospheric nuclear weapons testing) to > 10,000 yr. Because many of the published 14C measurements of soil organic material were made since the 1960s, the reported ages reflect varying degrees of bomb 14C contamination. To correctly interpret the radiocarbon age of soil organic matter as a mean residence time, 14C mea- surements must be made of pre-bomb soils. The rate of infiltration of the 14C produced by atmospheric nuclear weapons testing into the soil carbon reservoir can be a useful tool for deciphering carbon turnover in soils on time scales of decades to hundreds of years. O'Brien & Stout (1978), O'Brien (1984,1986) and Harkness, Har- rison & Bacon (1986) have shown that the increase in 14C content in bulk soil organic matter can only be explained if soil organic matter is a mixture of components that accumulate and decay at different rates. Fractionation of soil organic matter by chemical or physical means separates soil organic matter into components with different ages (eg, Campbell et al, 1967; Scharpenseel, Ronzani & Pietig,1968; Martel & Paul,

Evidence from Lewisian limestones for isotopically heavy carbon in two-thousand-million-year-old sea water

Abstract: A number of 2,000-million-year-old marbles have extraordinarily heavy carbon isotope signatures (δ13C ≈+12%0, PDB) 1,2, suggesting that there was a worldwide excursion in the carbon isotope composition of sea water at this time. To test this hypothesis we have measured the carbon isotope signatures of 2,000-million-year-old amphibolite facies marbles from the Scottish Lewisian. The occurrence of a major isotope excursion is confirmed by the heavy carbon isotope signatures of these rocks (δ13C up to +13%0 PDB), which we attribute to an origin contemporaneous with sedimenta-tion. This excursion coincides with a major change in the redox state of the oceans which is likely to have induced considerable changes in the carbon cycle. We suggest that the excursion was due to increased rates of organic carbon deposition resulting from an increase in organic productivity.

Influence of productivity variations on long-term atmospheric CO2

Abstract: Evidence from ice cores1 and deep-sea sediments2 shows that atmospheric CO2 concentration has varied by up to 40% over the past few hundred thousand years. As most of the exchangeable carbon resides in the deep sea, large changes in the atmosphere must have their source here. The distribution of carbon in the ocean is linked to biological productivity, the sinking and degradation of organic matter and calcium carbonate, and ocean circulation3. Carbon-cycle models predict different (and sometimes conflicting) shifts in productivity, and estimates of past productivity constrain the range of possible solutions. Here I use planktonic foraminifera species data in modern and ice-age Atlantic sediments to assess spatial patterns of changes in productivity. Ice-age export productivity was higher than at present by nearly 40% for the whole Atlantic, and by 90% under the Equator. These changes, if extrapolated to the global ocean, support models in which a significant portion of CO2 changes are driven by variations in biological productivity.

Tethyan carbonate carbon isotope stratigraphy across the Jurassic-Cretaceous boundary: An indicator of decelerated global carbon cycling?

Abstract: The carbon isotope record in four pelagic carbonate sections from the Southern Alps (northern Italy) across the Jurassic-Cretaceous boundary has been correlated to biostratigraphy and magnetostratigraphy. The carbon isotope curve from bulk carbonates shows a decrease from Kimmeridgian to Early Tithonian (CM24–CM22) values of δ13C=+2.07 (± 0.14)‰ to Late Tithonian and Berriasian (CM18–CM14) values of δ13C=+1.26 (± 0.16)‰. The change in the carbon isotope record coincides with changes in Tethyan calcite and silica accumulation rates, with a drop in the calcite compensation depth in the Atlantic and Tethys oceans and with changes in organic carbon burial along the Eurasian margin of the Tethys. Reduced surface water productivity due to diminished transfer rates of biolimiting elements into the Atlantic and Tethys oceans can explain these observations. The decreased transfer rates of elements such as silica or phosphorus from continents into the oceans resulted from drier climatic conditions and decreased water runoff on continents bordering the Tethys and Atlantic oceans. The proposed changes in Tithonian - Berriasian ocean chemistry and paleoclimate suggest that variations in the global carbon cycle were coupled with changes in the global hydrological cycle and in associated material cycles.

Food chain structure of the North Sea plankton communities: Seasonal variations of the role of the microbial loop

Abstract: Carbon flow in the plankton community was examined in various regions of the North Sea from 24 February to 4 March 1988. At this time, the spring phytoplankton bloom had begun in southern but not in northern regions. Bacterial abundance and production were highest in the Dogger Bank region where the spring bloom was under development, but there was no evidence of substantial carbon flow through the 'microbial loop' at this or any other station sampled. However, comparisons between ratios of bacterial carbon to phytoplankton carbon obtained on thls and a subsequent (May/June) cruise, show that the 'microbial loop' contributes substantially to carbon cycling during summer. During the Februarymarch cruise, copepod production rates were substantially higher in the southern than in the northern North Sea. For all stations it was estimated that < 5 % of total daily primary production was grazed by the copepod community. The bulk of the primary production occumng in the North Sea at this time of the year is, therefore, transferred directly to the benthos.

Modelling the seasonal contribution of a CO2 fertilization effect of the terrestrial vegetation to the amplitude increase in atmospheric CO2 at Mauna Loa Observatory

Abstract: An observed increase of the amplitude of the seasonal cycle of atmospheric CO 2 at Mauna Loa Observatory has been examined. Previous global carbon cycle studies seemed to suggest, at least qualitatively, that the observed increase may be entirely due to a CO 2 fertilization effect on the terrestrial biota. The present detailed theoretical investigation shows that a pure CO 2 stimulation of the net primary production may indeed lead to an amplitude increase of 0.15 plus 0.17% yr -1 and minus 0.10% yr -1 as compared to the measured value of 0.67 ± 0.25% yr -1 for the period between AD 1958 and AD 1987. This result is based on the assumption of a long term fertilization factor β with a range between 0.15 and 0.60, taken to be equal to the mesaured short term fertilization factor β, obtained in CO 2 enrichment studies with exposure times generally smaller than 1 year. The experimental evaluation of the difference between the relative increase of the summer (peak to trough) and winter (trough to peak) amplitude gives information on the carbon sequestered annually by the terrestrial ecosystems. With the estimated respiration response factor, which characterizes the fraction of the additional production that is consumed by ecosystem respiration, equal to 0.75, and an assumed long-term CO 2 fertilization factor, β, equal to 0.375, acceptable agreement between prediction and measurements is obtained, amounting to a mean annual increase in living biomass of 0.7 Gt C, while a corresponding portion may be stored in soils. The fact that the fertilization alone predicts the observed difference but not the absolute value of both the summer and winter amplitude, leads to the conclusion that other external effects are operative, which are not directly related to the fertilization phenomenon of the vegetation and which influence to an equal extent the summer and winter amplitude. Two such external contributions have been identified; they are both related to the increased fossil fuel carbon input into the Northern Hemisphere: (1) the seasonality of the fossil fuel consumption in the Northern Hemisphere is approximately in phase with the relative uptake or release of CO 2 by the land vegetation and leads to a small contribution to the increase in amplitude, in the range between 0.01 and 0.08% yr -1 ; (2) the seasonally different transequatorial transport of fossil fuel carbon creates a seasonal behavior which again is approximately in phase with the biota and leads to an additional contribution in the range of 0 to 0.31% per year depending on the wind fields used. DOI: 10.1111/j.1600-0889.1989.tb00137.x

Phytomass and detrital carbon storage during forest regrowth in the southeastern United States Piedmont

Abstract: Carbon in soil, forest floor, and phytomass was estimated for two chronosequences of loblolly pine (Pinustaeda L.) plantations, as well as agricultural fields and natural Virginia pine (P. virginia...

Bacteria and heterotrophic flagellates in the pelagic carbon cycle in the northern Baltic Sea

Abstract: The annual course of phytoplankton and bacterial productivity and the carbon requirement of heterotrophic flagellates were studied in the Tvamlinne area, northern Baltic Sea, during 1986. Phytoplankton productivity had a strong spring maximum, which was followed by a bacterial productivity peak formed by cold-adapted bacteria. In summer bacterial productivity was positively correlated with water temperature. Annual bactenal productivity was 15 % of net primary productivity. According to our calculations algal exudation could fulfil 50 to 65 % of the annual bacterial carbon requirement. Bacterial production could satisfy only about half to the flagellate carbon requirement Thls suggests that in order to meet their carbon requirement, heterotrophic flagellates also have to graze on small algae. Of the total net primary production, about 35 % was utilized directly by bacteria or heterotrophic flagellates. This emphasizes the importance of heterotrophic microbes in the pelagic carbon cycle of the northern Baltic Sea.

Evolution of the Global Biogeochemical Sulphur Cycle

Abstract: Part 1 Evolution of the sulphur cycle through geoloogical time: evolution of the sulphur cycle in the Precambrian, M.Schidlowski modelling the natural cycle of sulphur through Phanorozoic Time, W.T.Holser et al local and global aspects of the sulpher isotope age curve of oceanic sulphate, H.Nielsen contribution of endogenous sulphur to the global biogeochemical cycle in the geological past, A.Yu.Lein and M.V.Ivanov evolution of the sulpher cycle in recent millennia, P.Brimblecombe et al. Part 3 Interaction of sulphur and carbon cycles in some modern ecosystems: interaction of sulphur and carbon cycles in marine sediments, G.W.Skyring et al sulphur emission and transformations at deep sea hydrothermal vents, H.W.Jannasch interaction of sulphur and carbon cycles in microbial mate, Y.Cohen et al.

Soil respiration in relation to abiotic factors, forest floor litter, root biomass and litter quality in forest ecosystems of Siwaliks in Northern India

Abstract: Soil water and litter moisture had significant effect on CO 2 rates (r=0.64 to 0.87, P<0.01). Under laboratory conditions, carbon mineralization in amended soil was influenced by nitrogen, lignin and C:N ratio of litter. Mean annual carbon output from the soil was 667, 519 and 345 g C m −2 yr −1 for mixed, pine and scrub forests, respectively. CO 2 −C output in soil respiration exceeded the input of carbon in litter deposition by 2 to 30% and was 1.76 to 3.40 times higher than the estimated loss of carbon in litter decomposition

Effect of model structure on the response of terrestrial biosphere models to CO2 and temperature increases

Abstract: The sensitivity of a number of different globally aggregated models of the terrestrial biosphere to changes of atmospheric CO2 and temperature is investigated. Net primary production (NPP) or net photosynthesis (NP) is modeled as a logistic function, with enhancement due to increased CO2 using the β factor widely used in global carbon cycle models. NPP also increases with temperature using a Q10 of 1.4, while respiration and coefficients for translocation and for detritus to soil, and soil to soil, carbon transfers increase with a Q10 of 2.0. The pathway of carbon flow to the slowly overturning soil reservoir has a significant effect on equilibrium sensitivity of total carbon mass to temperature increases if the transfer coefficient from the rapidly to slowly overturning soil reservoir is fixed; maximum sensitivity occurs if all the carbon entering the slowly overturning reservoir first passes through the rapidly overturning reservoir. If the transfer coefficient increases in parallel with the increase of soil respiration coefficient, the carbon pathway has no effect on equilibrium sensitivity, although the transient response depends strongly on the subdivision of the soil reservoir. Allowing the detritus to soil transfer coefficient to increase in parallel with the coefficient for detrital respiration reduces the equilibrium sensitivity of total carbon mass to temperature increases by about half. The variation in model response to CO2 and temperature increases using different model structures is generally comparable to the variation resulting from uncertainty in feedback parameters.

Managing atmospheric CO2

Abstract: A coupled carbon cycle-climate model is used to compute global atmospheric CO2 and temperature variation that would result from several future CO2 emission scenarios. The model includes temperature and CO2 feedbacks on the terrestrial biosphere, and temperature feedback on the oceanic uptake of CO2. The scenarios used include cases in which fossil fuel CO2 emissions are held constant at the 1986 value or increase by 1% yr−1 until either 2000 or 2020, followed by a gradual transition to a rate of decrease of 1 or 2% yr−1. The climatic effect of increases in non-CO2 trace gases is included, and scenarios are considered in which these gases increase until 2075 or are stabilized once CO2 emission reductions begin. Low and high deforestation scenarios are also considered. In all cases, results are computed for equilibrium climatic sensitivities to CO2 doubling of 2.0 and 4.0 °C. Peak atmospheric CO2 concentrations of 400–500 ppmv and global mean warming after 1980 of 0.6–3.2 °C occur, with maximum rates of global mean warming of 0.2–0.3 °C decade−1. The peak CO2 concentrations in these scenarios are significantly below that commonly regarded as unavoidable; further sensitivity analyses suggest that limiting atmospheric CO2 to as little as 400 ppmv is a credible option. Two factors in the model are important in limiting atmospheric CO2: (1) the airborne fraction falls rapidly once emissions begin to decrease, so that total emissions (fossil fuel + land use-induced) need initially fall to only about half their present value in order to stabilize atmospheric CO2, and (2) changes in rates of deforestation have an immediate and proportional effect on gross emissions from the biosphere, whereas the CO2 sink due to regrowth of forests responds more slowly, so that decreases in the rate of deforestation have a disproportionately large effect on net emission. If fossil fuel emissions were to decrease at 1–2% yr−1 beginning early in the next century, emissions could decrease to the rate of CO2 uptake by the predominantly oceanic sink within 50–100 yrs. Simulation results suggest that if subsequent emission reductions were tied to the rate of CO2 uptake by natural CO2 sinks, these reductions could proceed more slowly than initially while preventing further CO2 increases, since the natural CO2 sink strength decreases on time scales of one to several centuries. The model used here does not account for the possible effect on atmospheric CO2 concentration of possible changes in oceanic circulation. Based on past rates of atmospheric CO2 variation determined from polar ice cores, it appears that the largest plausible perturbation in ocean-air CO2 flux due to changes of oceanic circulation is substantially smaller than the permitted fossil fuel CO2 emissions under the above strategy, so tieing fossil fuel emissions to the total sink strength could provide adequate flexibility for responding to unexpected changes in oceanic CO2 uptake caused by climatic warming-induced changes of oceanic circulation.

Global Biogeochemical Cycles and Climate

Abstract: This paper highlights some important questions and problems involving greenhouse gas global cycles and climate response. Simplified biogeochemical cycles of the greenhouse gases CO2, CH4 and N2O, and of the atmospheric compounds of sulfur are presented with particular emphasis on exchange fluxes involving Earth’s surface and the atmosphere, where possible long-term natural fluxes are compared to gas fluxes resulting from human activities. It is demonstrated that the geological cycling behavior of these gases has been perturbed significantly by anthropogenic fluxes.

Carbon flows in the biosphere: present and future

Abstract: The atmosphere, biosphere and ocean surface layers contain approximately equal amounts of carbon (the deep ocean contains over 50 times as much). The flux of carbon between these pools is dominated by the process of photosynthesis which is itself influenced by the CO 2 concentration of the atmosphere. Over the last 200 years deforestation and now fossil fuel combustion have added CO 2 to the atmosphere to increase the concentration by 27%—half the increase occurred over the last 30 years. The resulting greenhouse effect has been accompanied by an increase in the global average temperature of about 0.5°; other 9greenhouse gases9 (N 2 O 1 O 3 , CFCs, CH 4 ) are also contributing to the warming. Present uncertainties with estimating carbon flows result from the disputed contribution of deforestation, the level of increased plant productivity and carbon storage due to CO 2 fertilization, and problems with estimating net primary production. Uncertainties in estimating future carbon balances arise from the extent of fossil fuel use especially by USA, USSR and China, the degree of control of greenhouse gas emissions, the CO 2 fertilization effect on plant productivity and vegetation responses (including moisture availability) and the rate of change of the climatic factors resulting from changing carbon fluxes.

Carbon content of sediments of small reservoirs

Abstract: Carbon content was measured in sediments deposited in 58 small reservoirs across the US Reservoirs varied from 02 to 4,000 km{sup 2} in surface area The carbon content of sediment ranged from 03 to 56 percent, with a mean of 19 {plus minus} 11 percent No significant differences between the soil and sediment carbon content were found using a paired t-test or ANOVA The carbon content of sediments in reservoirs was similar to the carbon content of surface soils in the watershed, except in watersheds with shrub or steppe (desert) vegetation Based on the sediment accumulation rates measured in each reservoir, the calculated organic carbon accumulation rates among reservoirs ranged from 26 to 3,700 gC m{sup {minus}2} yr{sup {minus}1}, with a mean of 675 {plus minus} 739 gC m{sup {minus}2} yr{sup {minus}1} The carbon content and accumulation rates were highest in sediments from grassland watersheds High variability was found in carbon content, carbon accumulation, and sediment accumulation rates due to individual watershed and reservoir characteristics rather than to any broad physiographic patterns The carbon accumulation rates in these reservoir sediments indicate that reservoir sediments could be a significant sink of organic carbon

Permian‐triassic carbon‐isotope anomaly in Greenland and in the southern Alps

Abstract: A carbon isotopic study of selected samples of apparently continuous Permian‐Triassic boundary sections from Jameson Land (Greenland) and from the Southern Alps (Italy) revealed a negative δ1 3C sh...

Estimating a carbon/chlorophyll ratio in nannoplankton (Creteil Lake, S-E Paris, France)

Abstract: The phytoplankton biomass of the Creteil Lake was characterized through 47 paired measurements of particulate organic carbon and chlorophyll. When determining the tranfers of organic carbon in the lake, the need to convert the phytoplankton biomass into carbon units led to the estimation of a carbon to chlorophyll ratio using regression analyses. An average C:Chl ratio of 80 was found. C:Chl has been found to be highly variable but the value commonly used is C:Chl = 40. In Creteil Lake, the high C:Chl value would characterize the nannoplankton that dominated in the lake. No general conversion factor apparently exists for natural populations; thus, more studies may be necessary for a better knowledge of the carbon budget in lakes.

Modelling biospheric control of carbon fluxes between atmosphere, ocean and land in view of climatic change

Abstract: The amount of carbon in the atmosphere is less than in the terrestrial biosphere and much less than in the ocean. The level of atmospheric CO2 is the result of a delicate balance in exchange fluxes with ocean and biosphere. Climatic change has the potential to alter this balance.

Environmental Chemical Stress Effects Associated with Carbon and Phosphorus Biogeochemical Cycles

Abstract: Primary biological productivity on land and in waters forms organic materials made of six main elements—C, H, O, N, S, and P—and about a dozen minor elements that are important to the maintenance of organic structures and physiological functions of living organisms. The main elements are present in different proportions in aquatic and land plants. In the surface environment of the Earth, the elements carbon, sulfur, nitrogen and phosphorus mostly are found as separate chemical forms. Primary biological productivity represents a coupling mechanism that joins the biogeochemical cycles of the individual elements one to another.

Environmental Problems And Solutions: Greenhouse Effect, Acid Rain, Pollution

Abstract: GREENHOUSE EFFECT Observational and Theoretical Studies of Greenhouse Climate Effects, K.E. Taylor and S.L. Grotch Atmospheric Carbon Dioxide and the Global Carbon Cycle: The Key Uncertainties, T.H. Peng, W.M. Post, D.L. DeAngelis, V.H. Dale, and M.P. Farrell Uncertainty in the Projection of Carbon Dioxide Emissions, G.W. Yohe Ambient Air Co-Modeling in Alaska, R.A. Johnson, M. Anderson, and E. Lilly Influence of Green Plants on the World Carbon Budget, A.E. Lugo The Effects of Land Use Alteration on Tropical Carbon Exchange, J. Molofsky, E.S. Menges, C.A.S. Hall, T.V. Armentano, and K.A. Ault The Challenge of Sustaining Productivity in the Face of CO2-Induced Change, J.S. Hoffman ACID RAINS Acid Precipitation: A Review, U.M. Cowgill Effects of Acid Rain on Epiphytic Orchid Growth, Sr. J.K. Frei, C. Orenic, N. Smith, and H. Jeffer Design of an Economic and Efficient Treatment of Station for Acidic Streams, H.T. Gencsoy, J.G. Pappajohn, G.A. Clites, and P.E. Zurbuch ATMOSPHERIC POLLUTION Clean Fuels Prices Dependent on Regional Air Quality Standards, R.G. Thompson and F.D. Singleton, Jr. Environmental Control Impacts of Selected Alternate Fuels on Existing Power Plants, E.W. Stenby, W.W. Hoskins, and A.W. Donaldson Effect of NOx Control Technology on Efficient Utilization of Fuel, O.I. Ogunsola and M. Rashid Khan Industrial Energy Use, Nonattaintment and the Clean Air Act Reauthorization, P.J. Grogan, D.B. Garvey, and D.G. Streets A Utility Planning Model for the Study of Air Pollution Reduction, N. Tyle Mathematical Modelling for Sulphur Dioxide Removal from Stack Gases in a Fluidized Bed of Activated Sodium Carbonate, H. El. Abd and F. El Diwani I.C. ENGINE EMISSIONS Pollutant Emissions from Internal Combustion Engines Using Ethyl Alcohol-Water Blends and Gasoline as Fuels, R.S. Queioz, A.F. Orlando, and A.M.B. Bittencourt Control of the Emitted Pollutants of a High Speed Compression Ignition Engine by Supplementary Vapor-Gasoline Fueling, D.A. Kouremenos, C.D. Rakopoulos, and P. Kostiopoulos MICROPOLLUTANTS Environment Impact Evaluation of Micropollutants from Combustion Phenomena, L. Cassitto Destruction of the Organo-Chlorinated Micropollution in Combustion Processes, L. Cassitto RADIOACTIVE POLLUTANTS Comparison of Observed and Predicted Kr-85 Air Concentrations, M. Yildiran and C.W. Miller Analysis of Global Ultraviolet Radiation Measurements at Futhaulia, Baghdad, M. Al-Riahi, A. Akrawi, and S. Hikmat Energy and Radiative Precursor Emissions, J.A. Emonds, D.L. Wuebbles, and M.J. Scott Radionucleotides in U.S. Coals and Their Implications with Respect to Energy Development, C.A. Bissell and R.D. Brown OIL SPILLS Oil Transport Management and Marine Pollution Control: Oil Spill Prevention, E.L. Bourodimos and C.C. Carvounis WATER QUALITY Relationship of Regional Water Quality to Aquifer Thermal Energy Storage, R.D. Allen and J.R. Raymond Comparative Physico-Chemical Analysis of Drinking, Ground, and Industrial Waste Water of Jodhpur, R.C. Kapoor, J. Kishan, K.C.K. Mathur, and P. Sharma ENERGY AND ENVIRONMENT The Energy Transformation-Ecology Interface form a Nonlinear, Noneqilibrium Thermodynamic Perspective, A.A. Oni Alternative Gaseous Fuels Safety Assessment, M.C. Krupka, A.R. Peaslee, Jr., and H.L. Laquer National Estimates of Residential Firewood and Air Pollution Emissions, F.W. Lipfert and J.L. Dungan Air Quality Effects of Solar Energy Development, L. Habegger, F. Lipfert, and K.J. Allwine, Jr. Cleaner and Economically Self-Sustaining Energy for Developing Countries, A.V.K. Suryanarayana Coal Gasification Plant for Philadelphia - A Case History of Environmental Consideration Impacting Design, R.P. Stringer Index