Inorganic Nitrogen Compounds Research Articles

Effects on inorganic nitrogen compounds release of contaminated sediment treatment with in situ calcium nitrate injection.

Notable releases of nitrate, nitrite, and ammonia are often observed in contaminated sediment treatment works implementing in situ calcium nitrate injection. In order to provide extended information for making best decision of employing this in situ sediment remediation technology, in this study the releases of nitrate, nitrite, and ammonia from the sediment after the calcium nitrate addition operation was investigated in column setups designed to simulate the scenarios of a stagnant water (e.g., a pound or small lake) and a tidal-influenced water (e.g., a river mouth), respectively. Comparison with published aquatic toxicity data or authorized criteria was conducted to assess if there is any toxic effect that might be induced. Along with the vigorous N2 emission due to the denitrification reactions which occurred in the treated sediment, external loaded nitrate, intermediately produced nitrite, and indigenous ammonia in the sediment showed being mobilized and released out. Their promoted release and fast buildup in the overlying water to an excessive level probably cause toxic effects to sensitive freshwater living species. Among them, the potential ecological risk induced by the promoted sediment ammonia release is the greatest, and cautions shall be raised for applying the calcium nitrate injection in ammonia-rich sediments. The caused impacts shall be less violent in a tidal-influenced water body, and comparatively, the continuous and fast accumulation of the released inorganic nitrogen compounds in a stagnant water body might impose severer influences to the ecosystem until being further transferred to less harmful forms.

Partitioning between benthic and pelagic nitrate reduction in the Lake Lugano south basin

We evaluated the seasonal variation of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) rates in the sediments and the integrative N (and O) isotopic signatures of dissolved inorganic nitrogen (DIN) compounds in the overlying water column of the monomictic Lake Lugano south basin. Denitrification was the dominant NO−3 reduction pathway, whereas the contribution of anammox and DNRA to total benthic NO−3 reduction was < 6% and < 12%, respectively. Sedimentary denitrification rates were highest (up to 57.2 ± 16.8 µmol N m−2 h−1) during fully oxic bottom water conditions. With the formation of seasonal bottom water anoxia, NO−3 reduction was partitioned between water column and sedimentary processes. Total benthic NO−3 reduction rates determined in 15N‐label experiments and sediment—water interface N2 fluxes as calculated from water column N2 : Ar gradients revealed that sedimentary denitrification still accounted for ∼ 40% of total N2 production during bottom water anoxia. The partitioning between water column and sedimentary denitrification was further evaluated by the natural abundance stable N isotope composition of dissolved NO−3 in the water column. With anaerobic bottom water conditions, water column NO−3 concentrations gradually decreased, paralleled by an increase in δ15N— and δ18O— NO−3 from approximately 7‰ to 20‰ and from 2‰ to 14‰, respectively. Using a closed‐system (Rayleigh) model, the N and O isotope effects associated with community NO−3 consumption were 15ε ≈ 13.7‰ and 18ε ≈ 11.3‰, respectively. With the assumptions of a relatively low net N isotope effect associated with sedimentary denitrification (i.e., 15εsed = 1.5–3‰) vs. a fully expressed biological N isotope fractionation during water column denitrification (i.e., 15εwater = 20–25‰), our results confirm that 36–51% of reduction occurred within the sediment. The general agreement between the indirect (isotopic) approach and the flux and rate measurements suggests that water column nitrate isotope measurements can be used to distinguish between benthic and pelagic denitrification quantitatively.

Assessment of nitrate-N contamination in the Chunnakam aquifer system, Jaffna Peninsula, Sri Lanka.

Jaffna peninsula in Sri Lanka is an area of intensive agriculture using extensive organic and inorganic nitrogenous compounds and hence, this study was focused on assessing vulnerability of karstic aquifer system with specific focus on nitrate contamination, and compare loads of nitrate from agriculture. The total number of the wells sampled in the Chunnakam aquifer is 44. The coverage of wells with measurements of nitrate and nitrite concentrations in the database covering the study period from Januray, 2011 to August, 2011. The intrinsic vulnerability of the area is estimated by the DRASTIC model and the modified DRASTIC method was used to determine the nitrate-specific vulnerability of the aquifers. Average concentrations of nitrate-N and nitrite-N during the study period were 4.869 and 0.014 mg/L respectively. The average number of wells exceeding permissible level of NO3–N is approximately 6–12, which means that about 14-28% out of the 44 wells. Modified DRASTIC (DI) index value computed as explained above increased from DI = 177 to a range of 182 to 197. In spite of the increase, the Modified DI values show that the aquifer vulnerability specific to nitrate contamination remains in “high” category. Although nitrogen loading at the domestic sources and irrigation is of the same order of magnitude, the loading from fertilizer input is much larger which is about 15 times higher. This finding suggests that the fertilizer input in agricultural areas constitute a significant contribution to the nitrogen content in the groundwater and soils in agricultural areas of Jaffna.

Inhibition of the de novo synthesis of PCDD/Fs on model fly ash by sludge drying gases

Sludge drying gases (SDG), evolving from drying and mild thermal decomposition (<300°C) of raw sewage sludge contain NH3 and SO2 as well as other N- and S-compounds. All of these are potential PCDD/Fs suppressants. It is indeed observed that these SDG suppress 2,3,7,8-substitued PCDD/Fs formation on Model Fly Ash (MFA) with an efficiency up to 97.6% in wt. units and 96% in I-TEQ, respectively. This suppression is strong for (the bulk of) PCDD/Fs, adsorbed on the model fly ash; conversely, sludge drying gases enhance PCDD/Fs desorption from MFA. Moreover, TCDD/Fs are suppressed least, possibly following stepwise dechlorination of higher chlorinated PCDD/Fs. Characteristics, such as the type, origins and amount of sludge, its moisture-, nitrogen- and sulfur content and the nature of the thermal treatment applied are all expected to influence upon the suppression capabilities. In this study three types of dry sludge are tested and applied as suppressant in four different amounts or modes. The quality of the sludge drying gases is continuously monitored: the Gasmet results reveal that NH3 and SO2 are the most important components of SDG. The MFA reaction residue is scrutinized by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analysis. A large number of particles attaching to the surface of model fly ash are observed by SEM. Moreover, EDS analysis reveals that part of the chlorine in MFA is carried away with the SDG and replaced by sulfur, so that eliminating chlorine may be part of the inhibition mechanism. However, further research is still needed to establish the optimum operating modes and to confirm the role of both inorganic and organic nitrogen and sulfur compounds in the suppression of PCDD/Fs formation on model fly ash.

Effects of ageing on elution behaviour of nitrogenous compounds in disposed wastes from landfill sites

Comparative studies of elution and cation exchange capacity (CEC) tests were applied to aged and fresh municipal and industrial solid wastes to examine the effects of ageing on the long-term elution behaviour of nitrogen on leachate in municipal and industrial solid waste landfill sites. Nitrogen in the leachate gradually eluted as organic nitrogen, but not upon transformation of organic nitrogen to elutable inorganic nitrogen compounds in the solid waste. Ammonium in the solid waste, retained similar to its interaction with clay minerals in soil, elutes when exposed to leachate by being replaced with highly concentrated cations or loses its positive charge in high pH in the leachate, which percolates down from the upper layer of the disposed waste. The quantity of ammonium adsorbed into the aged wastes through CEC measurement process by replacement with ammonium acetate was higher than that onto the fresh wastes. That difference in quantities can serve as an index of the ability of the solid waste to withhold ammonium in the leachate that percolates down the landfill layer. Those results demonstrate that ammonification of organic nitrogen in the waste is not the crucial step of the elution of nitrogenous compounds into leachate.

Macroalgae mitigation potential for fish aquaculture effluents: an approach coupling nitrogen uptake and metabolic pathways using Ulva rigida and Enteromorpha clathrata

Aquaculture effluents are rich in nitrogen compounds that may enhance local primary productivity, leading to the development of algae blooms. The goal of this study was to assess the potential use of naturally occurring green macroalgae (Ulva and Enteromorpha) as bioremediators for nitrogen-rich effluents from a fish aquaculture plant, by evaluating their respective uptake dynamics under controlled conditions. Ulva and Enteromorpha were incubated separately in aquaculture effluent from a local pilot station. Algae tissue and water samples were collected periodically along 4 h. For each sample, nitrate, nitrite, and ammonia concentrations were quantified in the effluent, while internal algae reserve pools and nitrate reductase activity (NRA) were determined within the algae tissues. Both macroalgae absorbed all dissolved inorganic nitrogen compounds in less than 1 h, favoring ammonia over nitrate. Ulva stored nitrate temporarily as an internal reserve and only used it after ammonia availability decreased, whereas Enteromorpha stored and metabolized ammonia and nitrate simultaneously. These distinct dynamics of ammonia and nitrate uptake supported an increase in NRA during the experiment. This study supports the hypothesis that Ulva or Enteromorpha can be used as bioremediators in aquaculture effluents to mitigate excess of dissolved inorganic nitrogen.

Regulation of Nitrogen Assimilation in Green Microalgae

AbstractGreen microalgae have evolved a diversity of regulatory mechanisms for assimilating inorganic and organic nitrogen compounds. Ammonium, which is a preferred nitrogen source under most conditions, is usually assimilated via the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle. However, some green microalgae assimilate ammonium via NADP-dependent glutamate dehydrogenase (GDH) under high ammonium conditions (e.g., Chlorella species), or under conditions of restricted nitrogen supply (Stichococcus bacillaris, which possesses a high-affinity NADP-GDH). NAD-dependent glutamate dehydrogenase appears to function mainly under heterotrophic conditions, and when amino acids serve as sources of nitrogen, thus suggesting a catabolic role for this enzyme. In S. bacillaris, when ammonium assimilation occurs chiefly via the GS/GOGAT cycle, GS1 (cytosolic isozyme) appears to be responsible for glutamine synthesis in the dark, and GS2 (chloroplastic isozyme) in the light. S. bacillaris synthesizes GS2 and N...

Cultural characteristics of Cordyceps militaris strain 'Yedang 3' on various media and nutritional conditions

The effects of environmental and nutritional requirement such as temperature, pH, different media, carbon, nitrogen, and carbon-to-nitrogen ratio on the mycelial growth of Cordyceps militaris strain 'Yedang 3' were studied. The optimum temperature and pH for the growth of mycelium were <TEX>$20-25^{\circ}C$</TEX> and pH 6-7, respectively. Out of ten media tested, mushroom complete media (MCM) was the best medium for fast mycelial growth, and Sabouraud's dextrose agar yeast extract (SDAY), malt extract yeast extract agar (YMA) also were favored. The color and shape of colonies varied in different media. The best carbon sources for mycelial growth were fructose, mannitol, and sucrose, whereas the best nitrogen sources were tryptone and peptone. However, mycelia grew slowly in inorganic nitrogen compounds such as <TEX>$NH_4Cl$</TEX>, <TEX>$(NH_4)_2SO_4$</TEX>, <TEX>$NH_4NO_3$</TEX>, and <TEX>$NaNO_3$</TEX>. The optimum C:N ratio observed on the culture media was 30-40 range. These results provided basic information on cultural characteristics of vegetative growth and might be useful for spawn production in Cordyceps militaris.

Evaluation of the microbial diversity of denitrifying bacteria in batch reactor

Microbial communities in an industrial activated sludge plant may contribute to the denitrification process, but the information on the microorganisms present in denitrifying reactors is still scarce. Removal of inorganic nitrogen compounds can be accomplished by the addition of carbon sources to the biological process of denitrification. Ethanol is an economically viable alternative as a carbon source in tropical countries like Brazil, with large-scale production from sugarcane. This paper reports the successful aplication of activated sludge with nitrate and ethanol in a batch anaerobic reactor. The operation lasted 61.5 h with total consumption of nitrate in 42.5 h, nitrite generation (2.0 mg/L) and ethanol consumption (830.0 mg/L) in 23.5 h. Denitrifying cell counts by the most probable number at the start of the operation were lower than at the end, confirming the ability of the inoculum from activated sludge for the denitrification process. The samples from cell counts were identified as Acidovorax sp., Acinetobacter sp., Comamonas sp. and uncultured bacteria. Therefore, these species may be involved in nitrate reduction and ethanol consumption in the batch reactor.

Inorganic Nitrogen Compounds in Water Mains in Northern Poland and Their Implication for Health Risk

AbstractThe presence of nitrogen compounds significantly affects the quality of water intended for human consumption. The maximum contaminant level (MCL) of nitrogen in potable water in Poland was set up as follows: NO2−–0.5 and NO3––50 mg/L, NH4+–0.50 mg/L. For this reason, the objective of the study was to monitor the chemical composition of water as a priority basis for the water quality information system to provide consumers with water that meets the appropriate health and quality standards. The results of a multiyear study (1992–2003) carried out in four regions and at 12 monitoring sites in northern Poland showed NO2− and NO3− levels significantly below MCL limits. Low nitrate concentrations in water drawn from Quaternary water-bearing horizons indicate the absence of point sources of pollution. Ammonia levels exceeded MCL values at every monitoring site. Supernormal ammonia concentrations in raw water are indicative of the natural origin of ammonia ions. They are correlated with the depth of the...

Heterotrophic nitrification and aerobic denitrification by a novel Halomonas campisalis

A novel halophilic strain that could carry out heterotrophic nitrification and aerobic denitrification was isolated and named as Halomonas campisalis ha3. It removed inorganic nitrogen compounds (e.g. NO3 (-), NO2 (-) and NH4 (+)) simultaneously, and grew well in the medium containing up to 20 % (w/v) NaCl. PCR revealed four genes in the genome of ha3 related to aerobic denitrification: napA, nirS, norB and nosZ. The optimal conditions for aerobic denitrification were pH 9.0, at 37 °C, with 4 % (w/v) NaCl and sodium succinate as carbon source. The nitrogen removal rate was 87.5 mg NO3 (-)-N l(-1 )h(-1). Therefore, this strain is a potential aerobic denitrifier for the treatment of saline wastewater.

Influence of drying of the samples on the transformation of nitrogen and carbon compounds in mountain-meadow alpine soils

The drying of samples of mountain-meadow soils characterized by their permanently high moisture under natural conditions fundamentally changes the concentrations of the labile nitrogen and carbon compounds, as well as the patterns of their microbial transformation. When the soil samples are dried, a four- to fivefold increase in the content of the extractable organic nitrogen compounds, carbon compounds, and inorganic nitrogen compounds is observed, while the content of nitrogen and carbon of the microbial biomass decreases by two-three times. The rewetting of the dried soil launches the process of the replenishment of the nitrogen and carbon reserves in the microbial biomass. However, even after two weeks of incubation, their values were 1.5–2 times lower than the initial values typical of the natural soil. The restoration of the microbial community in the samples of the previously dried soils occurs in the absence of a deficiency of labile organic compounds and is accompanied by their active mineralization and the low uptake of ammonium nitrogen by the microorganisms.

Effects of addition of tilapia on the abundance of periphyton in freshwater prawn culture ponds with periphyton substrates

An experiment was conducted to evaluate the effect of addition of tilapia on abundance of periphyton in freshwater prawn, Macrobrachium rosenbergii (de Man) in periphyton based culture system for a period of 120 days at Fisheries Field Laboratory Complex, Bangladesh Agricultural University, Mymensingh. A large pond (83×8.9 m) was drained completely and partitioned by galvanized iron sheet into 18 small ponds of 40 m2 each; of which 6 ponds were used for this experiment. The experimental ponds were divided into 2 treatments each with 3 randomly selected ponds. The absence and presence (0 and 0.5 individual m-2) of tilapia (Oreochromis niloticus) were investigated in 40 m2 ponds stocked with 3 prawn juveniles (5±0.05 g) m-2 with added substrates for periphyton development. A locally formulated and prepared feed containing 30% protein was supplied considering the body weight of prawn only. Addition of periphyton substrates significantly reduced the inorganic N-compounds (TAN, NO2-N, and NO3-N) in water column. Forty six genera of periphyton were identified belonging to the Bacillariophyceae (10), Chlorophyceae (21), Cyanophyceae (7), Euglenophyceae (2), Crustacea (1) and Rotifera (5) with significant difference (P&lt;0.05) of phyto-periphyton except Euglenophyceae and without significant difference (P&gt;0.05) of zoo-periphyton between the treatments. The abundance of periphyton biomass in terms of dry matter, ash, ash free dry matter and chlorophyll-a were significantly higher in tilapia-free ponds comparing to tilapia added ponds. Benthic organisms had no significant difference (p&gt;0.05) between the treatments. Addition of tilapia in periphyton-based system benefited the freshwater prawn culture through (i) reducing toxic inorganic nitrogenous compounds in water (ii) reducing demand for supplemental feed (iii) using periphyton as additional natural feed and, (iv)improving survival and production of prawn and tilapia.DOI: http://dx.doi.org/10.3329/jbau.v10i2.14924 J. Bangladesh Agril. Univ. 10(2): 313-324, 2012

Solubility of the labile forms of soil carbon and nitrogen in K2SO4 of different concentrations

The general pattern of the changes in the solubility of the labile carbon and nitrogen compounds with the changes in the concentration of the salt extractant (0.05 and 0.5 M K2SO4) has been determined for soils differing in their acidity and in their contents of organic matter and nitrogen. Different forms of extracted compounds react differently to changes in the salt concentration. The solubility of inorganic nitrogen compounds (NH4+ and NO3−) does not depend on the concentration of K2SO4. In most cases, the carbon and nitrogen of the microbial biomass manifest a tendency for increasing extractability with an increase in the concentration of the K2SO4 solution. A fundamental difference is characteristic of the organic carbon and nitrogen compounds, the solubility of which in 0.5 M K2SO4 increases in different soils by 1.5–3.9 times in comparison with their solubility in 0.05 M K2SO4.

Dissolved organic matter uptake in a temperate seagrass ecosystem

We assessed the utilization of inorganic and organic nitrogen compounds of different complexity by primary producers and bacteria in a seagrass ecosystem. Using double-labeled ( 13 C and 15 N) substrates, the net transfers from the dissolved nitrogen and carbon pools to phytoplank- ton, planktonic bacteria, epiphytes, seagrasses (Zostera noltii and Cymodocea nodosa), and a macroalga (Caulerpa prolifera) were quantified in field incubations. Phytoplankton was the largest nitrogen sink, followed by the epiphytic community. In contrast, carbon fixation was dom- inated by the macrophytes. Although compartment-specific variations existed, NH4 + was gener- ally preferred over NO3 � and urea. Specific uptake rates of individual amino acids were inversely related to their C:N ratio and their structural complexity (glycine > L-leucine > L-phenylalanine). In addition, biomarker-specific measurements (polar lipid-derived fatty acids and D-alanine) indi- cated increasing bacterial contributions to carbon uptake with increasing amino acid structural complexity. All primary producers acquired nitrogen from a complex pool of algae-derived dis- solved organic matter (DOM), but algae-derived dissolved organic carbon (DOC) was almost exclusively used by the planktonic compartment. In contrast, a similar complex pool of bacteria- derived DOM was not taken up in significant quantities by any of the primary producers. Our results illustrate that dissolved organic nitrogen (DON) can provide bioavailable nitrogen to pri- mary producers and bacteria in seagrass ecosystems on very short time-scales, and DON and DOC dynamics are largely uncoupled and must be investigated as 2 separate interacting pools.

Phytoplankton of the Middle Section of the Southern Bug River as the Index of Its Ecological State

The ecological state of the middle section of the Southern Bug River was assessed using the comprehensive approach. Relationship between the characteristics of phytoplankton (species number, diversity, numbers, and biomass) and the content of inorganic compounds of nitrogen and phosphorus in the water of the studied section of the river was analyzed. The factors significantly influencing phytoplankton species number were not revealed. However, several stations invite further monitoring.

Trends in salinity and inorganic nitrogen compounds in the Berre lagoon (1994–2011) bacterial activities and nitrogen budgets

The Berre lagoon receives freshwater from two natural rivers but the implementation of the hydroelectric power plant led to strong changes in the ecosystem structure and functioning. Sediments are important sites for nitrogen cycling because the O2 sharp gradient allows oxic nitrification as well as anoxic denitrification and anammox to operate in close proximity. Seasonal and short-term variations in the coastal nitrogen processes were quantified at two stations: SA1 located in the northern part of the lagoon directly under the inflows of freshwater and SA3 in the southern part of the lagoon influenced mainly by the marine water inflows. Results revealed that most of the nitrate formed by nitrification was denitrified. Total denitrification was the main N2 removal process. The high primary production based on N–NH4+ might be explained by mineralization rates, while the primary production based on N–NO3- was not fully explained by nitrification.

Impact of declining atmospheric deposition on forest soil solution chemistry in Flanders, Belgium

Throughout Europe and the USA, forest ecosystem functioning has been impacted by long-term excessive deposition of acidifying compounds. In this study, we report on trends in stand deposition and soil solution fluxes of inorganic nitrogen (N) and sulphur (S) compounds over a 17-year period (1994–2010) in five ICP Forests monitoring plots in Flanders, northern Belgium. Deposition was dominated by N, and primarily NH4+. Deposition of SO42− and NH4+ declined by 56–68% and 40–59% respectively. Deposition of NO−3 decreased by 17–30% in deciduous forest plots, but remained stable in coniferous forest plots. The decrease of N and S deposition was parallelled by a simultaneous decline in base cation (BC = Ca2+ + K+ + Mg2+) deposition, resulting in a 45–74% decrease of potentially acidifying deposition. Trends in soil solution fluxes of NH4+, NO3−, SO42− and BC mirrored declining depositions. Nitrate losses below the rooting zone were eminent in both coniferous forest plots and in one deciduous forest plot, while net SO42− release was observed in two deciduous forest plots. Critical limits for BC/Al ratio were exceeded at the three plots on sandy soils with lower cation exchange capacity and base saturation. Soil solution acid neutralizing capacity increased but remained negative, indicating that soil acidification continued, as the start of recovery was delayed by a simultaneous decrease of BC depositions and short-term soil buffering processes. Despite substantial reductions, current N deposition levels still exceed 4–8 times the critical load for safeguarding sensitive lichen species, and are still 22–69% above the critical load for maintaining ground vegetation diversity.

Biodegradation of nitrophenol compounds and the membrane fouling trends in different submerged membrane bioreactors

Abstract Phenolic compounds are commonly used in industry and discharged into water. The objectives of this study were to evaluate the performance of submerged membrane bioreactors (MBRs) to simultaneously remove nitrophenols (metabolic uncouplers) and inorganic nitrogen compounds from wastewater and to determine the membrane fouling trends in two different types of MBRs: CSTR-MBR (continuous stirred tank reactor MBR) and MLE-MBR (modified Ludzack Ettinger MBR). At a target solids retention time of 110 day, a mixture of nitrophenol compounds (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol) was continuously dosed to the MBRs at the influent concentrations of 0.05 mM each. The nitrophenol removal efficiencies ranged from 87% to 96% while the total inorganic nitrogen removal efficiencies were 52% and 75% for the CSTR-MBR and MLE-MBR, respectively. The metabolic uncoupling by nitrophenols resulted in lower adenosine triphosphate (ATP) yield of 0.06 mg/g VSS and bound extracellular polymeric substances (EPS) of 20.5 mg/g VSS from the CSTR-MBR compared to the values of 0.10 mg ATP/g VSS and 30.7 mg EPS/g VSS from the MLE-MBR. There was a direct relationship between the EPS content and fouling, as membranes were less susceptible to fouling in the CSTR-MBR because of the reduced release of EPS due to the metabolic uncoupling by nitrophenols. These results suggest that both MBRs are effective in removing nitrophenols. While the MLE operation resulted in more efficient nitrogen removal, the CSTR-MBR configuration appears to be superior with less membrane fouling, an added benefit to the CSTR process, which is capable of reducing the toxicity of chemicals due to rapid mixing and dilution and widely used in industrial operations.

Ecological aspects of carbon and nitrogen isotope ratios of cyanobacteria

Variation in the δ13C of a cultured marine cyanobacterium (Agmenellum quadruplicatum, strain PR-6) is described with an emphasis on the relationships between growth rate, pCO2, and δ13C. An average nitrogen isotope fractionation of 1.0017 was obtained during N2 fixation by cultured marine cyanobacteria. This result suggests that nitrogen supply via N2 fixation may be characterized by a low δ15N, down to ca. -2‰ in marine environments, where the average δ15N is higher (at ca. 6‰) for major inorganic nitrogenous compounds such as nitrate. The natural abundances of nitrogen and carbon isotope ratios for cyanobacteria collected from the McMurdo Dry Valleys, Antarctica, were characterized by extremely low δ15N and widely ranging δ13C. Summarizing these and other data obtained, an isotopic map of cyanobacteria and other plankton in aquatic ecosystems was constructed and the ecological implications are discussed. Our results suggest that the δ13C of marine phytoplankton is positively correlated with sea surface temperature and can be a useful parameter for estimating in situ growth rates in the open ocean.