Variations In Nutrient Concentrations Research Articles

Nature and nurture in the dynamics of C, N and P during litter decomposition in Canadian forests

We measured changes in carbon (C), nitrogen (N) and phosphorus (P) concentrations and mass of 10 foliar litters decomposing over 12 years at 21 sites across Canada, ranging from subarctic to temperate, to evaluate the influence of litter quality (nature) and forest floor (nurture) on N and P dynamics. Most litters lost P faster than N, relative to C, except in one litter which had a high initial C:P quotient (2,122). Net N loss occurred at mass C:N quotients of between 33 and 68, positively correlated with the C:N quotient in the original litter, and net P loss likely occurred at C:P quotients between 800 and 1,200. Forest floor properties also influenced N and P dynamics: the higher the C:N or C:P quotient in the surface soil organic matter, the smaller the proportion of initial N or P left in the decomposing litter, relative to C. There was a convergence of C:N and C:P quotients as the litters decomposed, with an overall mass ratio of 427:17:1 when the litters reached 20% original C remaining. These results, covering a wide range of sites and litters and thus decomposition rates, showed that the C:N:P quotients followed similar trajectories and converged as the litters decomposed. The relative loss of N and P was affected by both the initial litter nutrient concentration and the chemistry of the site forest floor, with the former being more important than the latter, resulting in spatial variations in nutrient content of the forest floor.

Leaf nutrient concentration as an indicator of Populus and Tamarix response to flooding

Plants growing in infertile environments are able to produce more biomass per unit of nutrient taken up than plants of fertile habitats, and also to minimize nutrients loss by resorbing them from senescing leaves. The leaf nutrient concentration variability of two co-existing riparian tree genera (Populus and Tamarix) along a flood inundation gradient was examined to infer nutrient limitation and to compare nutrient use strategies in the two genera. To that end, seasonal and spatial variability in leaf nitrogen (N) and phosphorus (P) concentration (i.e., % dry mass of N and P) were analyzed in 720 samples of leaves (2 tree genera × 3 seasons × 12 sites × 10 tree replicates). Both Populus and Tamarix showed strong seasonal variability in leaf N and P concentrations, with values decreasing throughout the growing season. However, while N:P atomic ratio remained seasonally constant in Populus (N:P = 33), Tamarix shifted from N:P = 29 in spring to N:P = 36 and 37 in summer and fall. %N, %P and N:P atomic ratios were also spatially variable, but leaf litter N and P concentration (i.e., nutrient resorption proficiency) and leaf litter N:P generally followed the local flood inundation gradient as shown by linear mixed effects models. In particular, nutrient resorption was usually less proficient (higher terminal nutrient concentrations) at higher flood durations (in gravel bars and natural levees), whereas N:P increased in the drier sites (floodplain terrace). At floodplain level, a P-limitation that is higher than N-limitation seems to characterize the plant nutrient circulation in the riparian ecosystem studied. Tamarix was slightly more proficient in P resorption than Populus. The study shows that leaf nutrient concentration (e.g., N and P) derived from nutrient availability is partly controlled by the flood inundation regime and can be used as an indicator of nutrient limitation in forested floodplains. Subtle differences between tree genera provide an additional, novel explanation for the recent expansion of Tamarix in many arid and semi-arid rivers with altered hydrogeomorphic regimes.

Dynamics of seagrass and macroalgal assemblages in Saipan Lagoon, Western Pacific Ocean: disturbances, pollution, and seasonal cycles

Abstract Despite a wealth of laboratory experiments describing seagrass growth and competitive interactions with macroalgae under varying nutrient concentrations, there is limited information available from field studies conducted in complex natural environments. We examined ecological change over time in the Saipan Lagoon, Western Pacific Ocean. Here, seagrass (Halodule uninervis) canopy cover was quantified monthly at relatively small spatial scales over a 3-year period. Where watershed size and human population were low, there was a significant relationship with seasonal environmental cycles; cooler temperatures correlated with increased drift, red algal abundance and freshwater input increased green algae. Following cyclical macroalgal overgrowth, however, seagrass again became the dominant canopy. Conversely, in the presence of high human population and urbanization, seasonal cycles were absent and a seagrass-to-macroalgal transition was evident. Adjacent to a large watershed with moderate pollution, significant ties were found between seagrass emergence and winter-time disturbance events (large swells), as detached macroalgae that formed during summer months were removed annually. In summary, seagrass systems associated with Saipan Lagoon appear to be hierarchically controlled, following: 1) disturbances, 2) land-based pollution, and 3) seasonal environmental cycles.

Variations in paleoproductivity and the environmental implications over the past six decades in the Changjiang Estuary

Total organic carbon and organic carbon stable isotope, biogenic silica, chlorin were measured from a high resolution sediment core to indicate the variation in paleoproductivity and the environmental implications over the past decades (1942 to 1997) in the Changjiang Estuary. Based on these biomarkers, the shift in the phytoplankton community structure in the past decades was discussed in response to the long-term variations in nutrient concentrations and nutrient ratios. The results showed that the δ 13C values varied from −26.15‰ to −19.5‰, suggesting the combined organic carbon sources of riverine and marine organisms. Based on the biogenic proxies, paleoproductivity changes were categorized into three stages: low production before 1950; an increase in production with the dominance of diatoms during 1950 to 1980, consistent with increasing of nutrient concentrations; a decrease in production after 1980 when the diatom production decreased while the production of non-silicious phytoplankton increased due to high nutrient inputs, and high N/P and P/Si ratios in the Changjiang Estuary. The sedimentation records also indicated that the riverine organic carbon increased since 1980.

Nitrogen and phosphorous concentrations in runoff from a purple soil in an agricultural watershed

Abstract Nutrient loss from purple soils has been reported to increase pollution of the Yangtze River. However, few studies have addressed the variations of nutrient concentration in runoff during natural rainstorms in the regions. Nitrogen and phosphorus concentrations in runoff waters from a small agricultural watershed, in the purple soil region of southwest China, were investigated for four natural rainstorms occurred in a conventional double cropping system (wheat–corn) and another six rainstorms in a new triple cropping system (wheat–corn–sweet potato). The NO 3 − concentrations in runoff for the observed rainstorms generally varied from 1.0 to 3.5 g m −3 , which were noticeably affected by flow rates. A significant logarithmic correlation between NO 3 − concentrations and flow rates for each rainstorm was identified. In contrast, the concentrations of NH 4 + and dissolved reactive phosphorus (DRP) in runoff fluctuated substantially without a noticeable trend for each rainstorm. Positive linear correlation between the concentrations of DRP and sediment for each rainstorm tested was found under the circumstances of double cropping system. In addition, the ratios of NO 3 − to NH 4 + for the loss amount in 10 rainstorms varied from 1 to 7 for the triple cropping system and 16–29 for the double cropping system. Furthermore, the ratios of the sum of NO 3 − and NH 4 + to DRP for the loss amount in 10 rainstorms ranged from 12 to 79 depending on the cropping systems. Nitrate nitrogen was proved to be the main form of inorganic nitrogen loss in runoff water in the purple soil region. Compared with the conventional double cropping system, the new triple cropping system tends to cause more NH 4 + loss. These findings would help develop the effective erosion control strategies and select a suitable cropping system to reduce potential pollution hazards.

Relationships between local stand density and local species composition and nutrient content in the topsoil of pure and mixed stands of silver fir (Abies alba Mill.)

This study examined topsoil samples from the humic mineral horizon in four pure silver fir (Abies alba Mill.) and five mixed stands with beech (Fagus sylvatica L.), spruce (Picea abies L.; Karst.) and pine (Pinus sylvestris L.). In every stand, 60–70 sampling locations were chosen using a stratified random scheme that represented a gradient in local stand density and local species composition. One working hypothesis was that stand density and species composition affect the content of nutrients in the mineral humic soil horizon. Specifically, the analysis statistically tested for relationships between general and species-specific local stand density measures (basal area, sum of tree diameters weighted by distance, canopy openness) and the contents of total C, total N (in four stands), base cations (Ca2+, Mg2+, K+, Na+) and Mn2+ (in nine stands). A considerable variation in nutrient concentrations was observed; the coefficients of variation ranged from 0.21 to 0.38 for N, from 0.20 to 0.94 for the sum of base cations and from 0.56 to 0.95 for Mn. However, no clear relationship emerged between local stand density and the concentration of N and base cations; in five stands, manganese showed a negative correlation with local stand density. In the mixed fir-beech stand, significantly higher concentrations of Ca, K and Mn were found in the vicinity of beeches, and species-specific stand density explained up to 15, 29 and 34% of total variation in the content of these elements, respectively. Similar tendencies also appeared in the mixed stands with pine, although the relationships were weak. The results obtained for two fir-spruce stands were ambiguous. In sum, in the stands studied, small canopy gaps and inter-crown openings might not be considered ‘‘nutrient hot spots’’, and the admixed species, except for beech, had an insignificant effect on nutrient content in the humic mineral horizon.

Spatial and temporal variation of the nutrients in the sediment and leaves of two Brazilian mangrove species and their role in the retention of environmental heavy metals

Spatial and temporal variation of the nutrient concentrations in leaves and sediment between the roots of Laguncularia racemosa (L.) Gaertn. f and Rhizophora mangle L. was analyzed in the mangrove forest of the estuary of São Mateus River, Espírito Santo, Brazil. In leaves, the nutrients followed the sequence: N> Ca> K> Mg> S> P> Fe> Mn> Zn> Cu, and there were significant differences between species and sites studied. In general, the levels of K were higher in the dry season compared to the rainy season for both species analyzed while Ca and Cu showed higher concentrations in the rainy season for Laguncularia racemosa. In the sediment, the nutrients followed the sequence: Mg> Ca> Fe> K> Mn> P> Zn> Cu, in general, with lower concentrations at the site where the sediment was sandier. We observed a significant variation of nutrient concentrations in the sediment between the periods analyzed, but the seasonal pattern was not clear for all nutrients. Nutrient concentration profile found in leaves of both plant species was not correlated with concentrations found in the respective sediments. The concentration factor was less than 1.0 for Fe and between 1.0 and 3.7 for Mn, Zn and Cu. These results provide physiological evidences about the relevance of these tree species for the role of mangroves as biogeochemical barriers to the transit of heavy metals.

The Influence of Microtopography on Soil Nutrients in Created Mitigation Wetlands

AbstractThis study explores the relationship between microtopography and soil nutrients (and trace elements), comparing results for created and reference wetlands in Virginia, and examining the effects of disking during wetland creation. Replicate multiscale tangentially conjoined circular transects were used to quantify microtopography both in terms of elevation and by two microtopographic indices. Corresponding soil samples were analyzed for moisture content, total C and N, KCl‐extractable NH4–N and NO3–N, and Mehlich‐3 extractable P, Ca, Mg, K, Al, Fe, and Mn. Means and variances of soil nutrient/element concentrations were compared between created and natural wetlands and between disked and nondisked created wetlands. Natural sites had higher and more variable soil moisture, higher extractable P and Fe, lower Mn than created wetlands, and comparatively high variability in nutrient concentrations. Disked sites had higher soil moisture, NH4–N, Fe, and Mn than did nondisked sites. Consistently low variances (Levene test for inequality) suggested that nondisked sites had minimal nutrient heterogeneity. Across sites, low P availability was inferred by the molar ratio (Mehlich‐3 [P/(Al + Fe)] < 0.06); strong intercorrelations among total C, total N, and extractable Fe, Al, and P suggested that humic–metal–P complexes may be important for P retention and availability. Correlations between nutrient/element concentrations and microtopographic indices suggested increased Mn and decreased K and Al availability with increased surface roughness. Disking appears to enhance water and nutrient retention, as well as nutrient heterogeneity otherwise absent from created wetlands, thus potentially promoting ecosystem development.

Temporal variability of nutrient concentration in marine biofilm developed on acrylic panels

The quantification of chemical and biochemical composition is one of the common approaches to measure the biomass in biofilms. In the present study, temporal changes in the concentration of chemical and biochemical components like carbohydrate, protein, nitrate, nitrite, phosphate, calcium and magnesium were analysed for a period of one year by suspending acrylic panels at the Kudankulam waters in the Southeast Coast of India. Considerable variation in the concentration was observed in relation to exposure duration and also between sampling months. Carbohydrates showed the highest concentration of 2.32 mg cm − 2 on 10-day-old panels submerged during December 2005. Protein concentration reached a maximum of 0.676 mg cm − 2 during August 2005. Nitrate and nitrite showed their maximum concentration during April 2005. Except carbohydrate, all other compounds showed significant monthly variation, which indicates strong temporal variability in the organic and inorganic composition of biofilms. Carbohydrate concentration showed a significant decrease over exposure time in October and June. Results suggest that the observed temporal variability may be partly influenced by the concentration of these nutrients in the surrounding medium. A significant conclusion of this study is that biofilm development should be assessed over a range of temporal scales for advancing our understanding of biofilms.

Nutrient dynamics of field-weathered Delmarva poultry litter: implications for land application

To develop phosphorus-based agronomic application rates of phytase-diet, bisulfate-amended Delmarva poultry litter in conservation tillage systems, nutrient release dynamics of the organic fertilizer under local weather conditions were investigated. Delmarva poultry litter was placed in polyvinyl chloride columns to a depth of 5 cm and weathered in the field for 570 days. Leachate from the columns was collected and measured for concentrations of various nutrients. Cumulative release of the nutrients as a function of weathering time was modeled, and the nutrient supply capacity was determined. Poultry litter leachate contained high contents of dissolved organic carbon (15–31,500 mg L−1), nitrogen (N 5–7,070 mg L−1), phosphorus (P 5–230 mg L−1), potassium (K+ 2–7,140 mg L−1), and other nutrients. Release of most nutrients occurred principally in the first 100 days, but for P and calcium (Ca2+), it would last for years. The release kinetics of N followed a logarithm equation, while P and K demonstrated a sigmoidal logistic pattern. The nutrient supply capacity of surface-applied Delmarva poultry litter was predicted at 10.9 kg N Mg−1, 6.5 kg P Mg−1, 34.7 kg K+ Mg−1, 5.4 kg Ca2+ Mg−1, and 14.0 kg SO42− Mg−1. The results suggest that Delmarva poultry litter should be applied to conservation tillage systems at 6.6 Mg ha−1 that would furnish 25 kg P ha−1 and 63 kg N ha−1 to seasonal crops. In repeated annual applications, the rate should be reduced to 5.2 Mg ha−1, with supplemental N fertilization to meet crop N requirements.

Variation in Nutrient Content of Microbrewers Grains and Effect on Performance and Carcass Composition When Fed Wet to Growing-Finishing Swine

<h2>ABSTRACT</h2> The number of microbreweries and brew pubs producing craft beers is increasing. A survey of New Jersey microbrewery establishments was conducted to identify sources, types, and volumes of microbrewers grains (MBG) produced. Almost 1 million kilograms of wet MBG were produced annually in New Jersey. Nutrient content of MBG did not vary with site (brewing facility) or type of brew produced. The CP content of MBG (n = 142) was 25% less than that reported for brewers grains in the NRC or Dairy One Forage Laboratory database sets (20.9 vs. 28% CP; respectively), which may be due to the lower efficiency with which microbrewers remove starch from grains. Using wet MBG to replace 50% of the supplemental protein in a corn- and soybean meal-based diet tended (<i>P</i> = 0.07) to reduce ADG (0.83 vs. 0.92 kg/d) of growing-finishing hogs even though DMI was the same (3.0 kg/d). Brewers grains are low in Lys. Adequate protein and amino acid nutrition is critical in all swine diets for optimal performance.

Phytoplankton community in the tropical lake of Lagoa Santa (Brazil): Conditions favoring a persistent bloom of Cylindrospermopsis raciborskii

This study presents data on seasonal changes of the phytoplanktonic community of a small tropical lake, Lagoa Santa, in the Brazilian cerrado. Temporal variation in the community structure was small and we observed a permanent dominance of the cyanobacteria Cylindrospermopsis raciborskii. This dominance could be associated to the stability of several environmental conditions. Especially water temperature, always within the optimal growth range for C. raciborskii, and the constant mixed water column may have been important factors driving to the long term dominance of this species in the lake. Remarkable seasonal variation in rainfall, as well as the occasional and non-seasonal variation in nutrient concentrations, were important to explain changes in environmental and biological variables, but were not related to the dominance of C. raciborskii. Pearson's correlation and PCA could just in part explain the stable dominance of this cyanobacterium. Meteorological and chemical factors seem to have no clear control on the variability of the phytoplankton dynamics in Lagoa Santa. The weak relationship between C. raciborskii abundance and environmental variables points to additional intrinsic factors associated to this species that may be important in structuring the phytoplankton assemblage.

A 3D Hybrid Model for Tissue Growth: The Interplay between Cell Population and Mass Transport Dynamics

To provide theoretical guidance for the design and in vitro cultivation of bioartificial tissues, we have developed a multiscale computational model that can describe the complex interplay between cell population and mass transport dynamics that governs the growth of tissues in three-dimensional scaffolds. The model has three components: a transient partial differential equation for the simultaneous diffusion and consumption of a limiting nutrient; a cellular automaton describing cell migration, proliferation, and collision; and equations that quantify how the varying nutrient concentration modulates cell division and migration. The hybrid discrete-continuous model was parallelized and solved on a distributed-memory multicomputer to study how transport limitations affect tissue regeneration rates under conditions encountered in typical bioreactors. Simulation results show that the severity of transport limitations can be estimated by the magnitude of two dimensionless groups: the Thiele modulus and the Biot number. Key parameters including the initial seeding mode, cell migration speed, and the hydrodynamic conditions in the bioreactor are shown to affect not only the overall rate, but also the pattern of tissue growth. This study lays the groundwork for more comprehensive models that can handle mixed cell cultures, multiple nutrients and growth factors, and other cellular processes, such as cell death.

The Relationship between the Skeletonema costatum Red Tide and Environmental Factors in Hongsha Bay of Sanya, South China Sea

Abstract The red tide in Hongsha Bay caused by Skeletonema costatum (S. costatum) from April 27 to May 4, 2006, was monitored in this study. The dynamic variety of environmental factors, including chlorophyll a (chl a), temperature, salinity, pH, dissolved oxygen, chemical oxygen demand, nitrate, ammonium, nitrite, phosphate (PO43−), silicate, and iron (Fe), was observed and analyzed during the red tide in Hongsha Bay for the first time. The results indicated that the concentration of dissolved inorganic nitrogen was high (26.34 μmol/L) in Hongsha Bay. Because of the heavy rainfall from April 13 to 15, a large input of nutrients surged into the bay, causing an increase in the concentration of various nutrients, especially PO43−, which showed an obvious increase (from 0.72 to 1.45 μmol/L). The abundant nutrients provided fundamental nutrient supply for the rapid proliferation of S. costatum. Three critical environmental factors, including water temperature, and PO43− and Fe concentration, played an importa...

Nutrient release from bisulfate-amended phytase-diet poultry litter under simulated weathering conditions

Poultry litter generated on the Delmarva Peninsula is from phytase-modified bird diet and bisulfate amendment. To establish agronomic application rates in conservation tillage systems, bisulfate-amended phytase-diet poultry litter was investigated for its nutrient release kinetics and supply capacity under simulated weathering conditions. Delmarva poultry litter was packed in PVC columns (15 cm i.d. x 25 cm height) to a depth of 5 cm and leached intermittently with 600 mm of water for 190 days. Concentrations of various nutrients in leachate were analyzed and nutrient release kinetics were modelled. Poultry litter leachate contained high contents of dissolved organic carbon (DOC, 35-11,800 mg L(-1)), nitrogen (N 6-2690 mg L(-1)), phosphorus (P 45-225 mg L(-1)), potassium (K 20-6060 mg L(-1)), and other nutrients. Release of the nutrients occurred primarily in the starting 5 weeks and mostly followed a first order Exponential-Rise-to-Maximum model. Under the specified conditions, the poultry litter demonstrated a nutrient supply capacity of 11.7 kg N Mg(-1), 5.4 kg P Mg(-1), and 36.8 kg K Mg(-1). Release of the potentially plant-available N and K was nearly finalized within 190 days of leaching/weathering, but it would require two years for full release of the leachable P. The results indicate that with consideration of field conditions, surface application of bisulfate-amended phytase-diet Delmarva poultry litter at recommended 6.6 Mg ha(-1) to conservation tillage systems would largely provide P 25.0 kg ha(-1), N 106.6 kg ha(-1), and K 245.5 kg ha(-1) to seasonal crops.

Mussel isotope signature as indicator of nutrient pollution in a freshwater eutrophic lake: species, spatial, and seasonal variability

Stable nitrogen isotope ratios of five mussel species from littoral and pelagic areas were investigated with different trophic states in the eutrophic Lake Taihu, the third largest lake in China. Interpopulation variability for these mussels was relatively small in foot tissues because of the slow turnover time. Seasonal and spatial variations among the delta (15)N values of mussels might be due in part to the natural variation in delta (15)N values of potential food sources and the variation in the amount of human pollutions discharged into various locations of the lake. Although the increase of mussel delta (15)N values was accompanied by the increase of nutrient concentrations in most situations in this study, statistically significant correlations were only 22% of the total correlations in this survey, which might be attributed to the different time-scale variations in nutrient concentrations and isotope signatures and the unknown details of the trophic pathways and metabolism for incorporation of these nutrients.

Temporal variability in water quality of agricultural tailwaters: Implications for water quality monitoring

Accurate assessments of non-point source pollution and the associated evaluation of mitigation strategies depend on effective water quality monitoring programs. Intensive irrigation season water quality monitoring was conducted on three agricultural drains (6 h to daily sampling) along with analysis of decade long records from two larger agricultural drains (biweekly to monthly sampling) in the San Joaquin Valley, California. Analyses revealed significant temporal variability in concentrations of nutrients, salts, and turbidity over short time-scales (<1 day), as well as significant differences in monthly and annual mean concentrations. Statistical techniques were used to evaluate the sampling intensity required to meet rigorous confidence and accuracy criteria, as well as to evaluate the efficacy of different sampling strategies (e.g. grab samples versus composite samples). The number of samples required to determine mean constituent concentrations within 20% of the mean at a 95% confidence level ranged from 2 to 39 samples per month (SPM) for total phosphorus, 1–16 SPM for total nitrogen, 5–25 SPM for turbidity, and 1–3 SPM for electrical conductivity. Using a daily composite sample (4 subsamples per composite) instead of discrete samples was shown to maintain the same accuracy and confidence standards, while reducing the required sample number by up to 50%. This study emphasizes the value of a statistical approach for evaluating water quality monitoring strategies, and provides a framework through which cost–benefit analysis can be implemented in the development of monitoring plans.

EFFECT OF CARBONIC ANHYDRASE INHIBITORS ON THE INORGANIC CARBON UPTAKE BY PHYTOPLANKTON NATURAL ASSEMBLAGES(1).

The role of carbonic anhydrase (CA) in inorganic carbon acquisition (dissolved inorganic carbon, DIC) was examined in Alboran Sea phytoplankton assemblages. The study area was characterized by a relatively high variability in nutrient concentration and in abundance and taxonomic composition of phytoplankton. Therefore, the relationship between environmental variability and capacity for using HCO3 (-) via external CA (eCA) was examined. Acetazolamide (AZ, an inhibitor of eCA) inhibited the primary productivity (PP) in 50% of the samples, with inhibition percentages ranging from 13% to 60%. The AZ effect was more prominent in the samples that exhibited PP >1 mg C · m(-3) · h(-1) , indicating that the contribution of eCA to the DIC photosynthetic flux was irrelevant at low PP. The inhibition of primary productivity by AZ was significantly correlated to the abundance of diatoms. However, there was no a relationship between AZ effect and CO2 partial pressure (pCO2 ) or nutrient concentration, indicating that the variability in the PP percentage supported by eCA was mainly due to differences in taxonomic composition of the phytoplankton assemblages. Ethoxyzolamide (EZ, an inhibitor of both external and internal CA) affected 13 of 14 analyzed samples, with PP inhibition percentages varying from 50% to 95%. The effects of AZ and EZ were partially reversed by doubling DIC concentration. These results imply that CA activity (external and/or internal) was involved in inorganic carbon acquisition in most the samples. However, EZ effect was not correlated with pCO2 or taxonomic composition of the phytoplankton.

The significance of oxbow lakes for the ecosystem of afforested river valleys

The interest in significance of forest areas in water quality improvement has been increasing since creation of biogeochemical barriers became effective tools against the input of pollutants to surface water from diffuse sources. Along meandering river valleys, numerous floodplain lakes often appear as valuable water ecosystems but of advanced eutrophy. Their trophic status depends not only on the hydrological connectivity with the river but also land use in the direct vicinity of the reservoir. Research on water ecosystems in the postglacial river valleys in northern Poland contributed to identification of the role of woodland area in pollutants migration in the valley of the Łyna River. The study on the ecosystem concerned seasonal variation in nutrient concentrations (N and P) and bottom sediments properties in relation to hydrological conditions (water level fluctuations). Based on the collected data we attempted prediction of the reservoir lifetime. Depending on hydrological, geological and topographic conditions the origin of water supply of the basin is changing. Annual water level fluctuations in the range of 200 cm cause the basin capacity variation as much as 5 times. Nevertheless, water quality in the lake was conditioned by the riverine supply, the significant share in the lake feeding has groundwater supply from hillslope aquifer and seepage through alluvial aquifer. Contribution of every origin supply depends on river flow rate and valley water level, it depends on alluvial ground formations permeability and relief. Hillslope erosion of the concave bank was responsible for high nitrogen and phosphorus outflows. The research showed that primary and secondary production and freshets contributed to intensive deposition of bottom sediments in oxbow lake. The increase rate of sediment determined on the base of matter balance was 10 times higher than deposition rate of bottom sediments in glacial lakes. The accelerated processes of silting-up and shallowing and terrestialization of the valuable ecosystems indicate the necessity of floodpain lakes protection due to ecological functions they play in forestry landscape.

Nutrition induced pleomorphism and budding mode of reproduction in Deinococcus radiodurans

BackgroundMorphological adaptation is an important biological function of a microorganism to cope with its environment. Pleomorphism (to exist in a number of morphological forms) took centre stage in many discussions wherein a bacterium exhibits morphological transition and altered mode of reproduction in response to an environmental condition.FindingsTo strengthen the concept on pleomorphism in bacteria, we report here different cell morphologies of Deinococcus radiodurans in response to variation in nutrient concentration. From our studies we attempt primary evidence towards the presence of significant population of monomer cells of D. radiodurans in specific culture condition. In this report we also illustrate with scanning electron micrographs an unusual budding mode of reproduction in D. radiodurans which was not reported till date for this group of bacteria.ConclusionIn a holistic view the study reflects on bacterial shape (morphotypes) and the physiological adaptation to a particular nutrient environment. The discovery of budding mode of reproduction in Deinococcus will be of interest to microbiologists. It can serve as a model system to understand the mechanism of budding process at molecular level.