Free CO2 Concentrations Research Articles

Biotic and Abiotic Components of The River

This study offers a comprehensive analysis of the physico-chemical parameters of the Sarodha Dam in Kabirdham, Chhattisgarh, over three distinct periods: pre-autumn, autumn, and post-autumn of 2007. Key parameters examined include temperature, velocity, total solids, total suspended solids, total dissolved solids, turbidity, pH levels, dissolved oxygen content, free CO2 concentration, biochemical oxygen demand (BOD), chemical oxygen demand (COD), alkalinity, chlorides, sulphate levels, and fish species identification. The research identified 36 distinct fish species within the dam, underscoring the biodiversity present. Historically, water has been a crucial resource for human survival and development, with rivers playing a vital role globally. However, pollution from sewage and industrial effluents threatens these vital water bodies, leading to significant environmental and health issues. Despite advances in water treatment, urban piped water often remains contaminated, resulting in waterborne diseases such as jaundice, cholera, typhoid, and gastroenteritis. Pollution impacts rivers through chemical degradation and disruption of ecosystems, highlighting the need for interdisciplinary approaches to monitor and manage water quality effectively.

Assessment of the CO2 water bath therapy effectiveness on diabetic foot ulcers through VEGF and TNF-α levels

Vasculopathy is typically seen in diabetic patients, and can lead to foot ulcerations. Carbon dioxide (CO2) therapy was found to improve chronic wound healing in patients with vascular impairment. This type of therapy refers to the transcutaneous and subcutaneous application of CO2 as well as CO2 water baths for therapeutic purposes. In the method used herein, artificial CO2-containing water for foot bathing was generated by dissolving Carbothera® (MRE-SPA-MD; Mitsubishi Rayon Engineering, Tokyo, Japan) and generating CO2 (free CO2 concentration: 1,000–1,200 mg/L; pH 4.6). The foot of each patient was immersed in CO2-enriched water (depth of 20–30 cm, 37–38°C, 30-min duration) three times per week, for the next three months. Dramatic clinical improvement was observed in the CO2 water bath therapy group before and after the treatment, while both the blood levels of the vascular endothelial growth factor and of the tumour necrosis factor-alpha in these patients exhibited significant changes. The advantages of this method are the absence of pain and the protection against infection, while the improved angiogenesis and oxygena¬tion can result in healing of the chronic wound.

Imaging of CO2 and Dissolved Inorganic Carbon via Electrochemical Acidification-Optode Tandem.

Dissolved inorganic carbon (DIC) is a key component of the global carbon cycle and plays a critical role in ocean acidification and proliferation of phototrophs. Its quantification at a high spatial resolution is essential for understanding various biogeochemical processes. We present an analytical method for 2D chemical imaging of DIC by combining a conventional CO2 optode with localized electrochemical acidification from a polyaniline (PANI)-coated stainless-steel mesh electrode. Initially, the optode response is governed by local concentrations of free CO2 in the sample, corresponding to the established carbonate equilibrium at the (unmodified) sample pH. Upon applying a mild potential-based polarization to the PANI mesh, protons are released into the sample, shifting the carbonate equilibrium toward CO2 conversion (>99%), which corresponds to the sample DIC. It is herein demonstrated that the CO2 optode-PANI tandem enables the mapping of free CO2 (before PANI activation) and DIC (after PANI activation) in complex samples, providing high 2D spatial resolution (approx. 400 μm). The significance of this method was proven by inspecting the carbonate chemistry of complex environmental systems, including the freshwater plant Vallisneria spiralis and lime-amended waterlogged soil. This work is expected to pave the way for new analytical strategies that combine chemical imaging with electrochemical actuators, aiming to enhance classical sensing approaches via in situ (and reagentless) sample treatment. Such tools may provide a better understanding of environmentally relevant pH-dependent analytes related to the carbon, nitrogen, and sulfur cycles.

Hydrochemistry of Kupinde Lake at the Lesser Himalaya in Karnali Province, Nepal

Hydrochemical assessment of the freshwater lakes provides important insights into the sources of dissolved ions, geochemical processes, and anthropogenic activities taking place in the environment. This study focuses on the assessment of hydrochemistry and water quality of Kupinde Lake, Karnali Province, Nepal. Surface water samples were collected from 24 different locations of the lake in October 2021 and analyzed for 18 different physico-chemical parameters. The pH, temperature, electrical conductivity and total dissolved solids were measured on-site, and concentration of major ions (Ca2+, Mg2+, Na+, K+, NH4+, HCO3-, Cl-, SO42-, PO43-, NO3-), including hardness and free CO2 were measured in the laboratory. The results revealed that lake water was alkaline with abundance of the major ions in the following order: Ca2+ > Mg2+ > Na+> K+ > NH4+ and HCO3- > Cl- > SO42- > PO43- > NO3- for the cations and anions, respectively. The lake water was dominated by Ca-HCO3, indicating calcium carbonate dominated lithology in the area. Gibb’s plot and Piper diagram illustrated rock weathering as the most dominant process in controlling the hydrochemistry of the lake basin. The suitability of water for drinking and irrigation was determined using geochemical indices and WHO standards. The results indicated that the Kupinde Lake water could be used for drinking and irrigation purposes in terms of measured hydrochemical variables.

The “Oxygen Sink” of Bamboo Shoots Regulates and Guarantees the Oxygen Supply for Aerobic Respiration

The amazingly rapid growth of bamboo shoots requires strong respiration and provides a large amount of energy and intermediate metabolites. Strong aerobic respiration requires a large amount of O2. This raises the following question: What is the source and mechanism of O2 supply to meet aerobic respiration? However, currently, this remains unknown. The underground buds (US), the 2-m-high overground buds (AS), and the 8-m-high growth arrest buds (HS) of bamboo (Phyllostachys prominens) were collected to represent their different stages of growth and development. The fifth bamboo shoot node at each stage was sealed by two membranes, and treated in a polyethylene zip-lock bag filled with air (21% O2 + 79% N2) and nitrogen (100% N2) for 1.5 h. The concentrations of free O2 and CO2 in the shoot cavities in polyethylene zip-lock bags, and the ethanol content in the shoot body before and after treatment were determined. In addition, the photosynthetic rates of the fifth bamboo internodes of 1 y/o, 2 y/o and 3 y/o bamboo in the field were measured. The results indicated that: (1) When treated with air and nitrogen, US, AS and HS mainly exhibited aerobic respiration, and there was almost no anaerobic respiration; (2) When treated with air, 59.66%, 54.47% and 45.84% of the O2 in the aerobic respiration of US, AS and HS came from the polyethylene zip-lock bag, 0.06%, 0.57% and 0.650% came from the shoot cavity, but 40.28%, 44.96% and 53.51% of the O2 was of an unknown source; (3) Treated by nitrogen, 0.19%, 4.71% and 4.79% of O2 in aerobic respiration of US, AS and HS came from shoot cavity, while the other 99.808%, 95.290% and 95.21% of O2 came from unknown sources; and (4) The photosynthesis of the fifth internodes of 1 y/o, 2 y/o and 3 y/o bamboo generated little oxygen that could not absolutely meet the huge O2 supply for aerobic respiration. It was concluded that the respiration of P. prominens shoots in its different growth and development stages was dominated by aerobic respiration. O2 supply pathways were mainly via the sheath stomata; however, there was little absorption from dissolved O2 in the soil water and little supply produced by shoot/stem photosynthesis. It was found that the large supply of oxygen in the aerobic respiration of bamboo shoots and young bamboo was of an unknown source under air treatment and nitrogen treatment, i.e., 40.28%–53.51% and 95.21%–99.81% of oxygen in the aerobic respiration of bamboo shoots and young bamboo was of unknown origin, respectively. Therefore, we proposed that bamboo shoots may exhibit the phenomenon of acting as an “oxygen sink”, which can provide a large amount of O2 from unknown sources to ensure the rapid growth of bamboo shoots and young bamboo.

Dissolved inorganic carbon export from rivers of Great Britain: Spatial distribution and potential catchment-scale controls

Dissolved inorganic carbon (DIC) fluxes from the land to ocean have been quantified for many rivers globally. However, CO2 fluxes to the atmosphere from inland waters are quantitatively significant components of the global carbon cycle that are currently poorly constrained. Understanding, the relative contributions of natural and human-impacted processes on the DIC cycle within catchments may provide a basis for developing improved management strategies to mitigate free CO2 concentrations in rivers and subsequent evasion to the atmosphere. Here, a large, internally consistent dataset collected from 41 catchments across Great Britain (GB), accounting for ∼36% of land area (∼83,997 km2) and representative of national land cover, was used to investigate catchment controls on riverine dissolved inorganic carbon (DIC), bicarbonate (HCO3−) and free CO2 concentrations, fluxes to the coastal sea and annual yields per unit area of catchment. Estimated DIC flux to sea for the survey catchments was 647 kt DIC yr−1 which represented 69% of the total dissolved carbon flux from these catchments. Generally, those catchments with large proportions of carbonate and sedimentary sandstone were found to deliver greater DIC and HCO3− to the ocean. The calculated mean free CO2 yield for survey catchments (i.e. potential CO2 emission to the atmosphere) was 0.56 t C km−2 yr−1. Regression models demonstrated that whilst river DIC (R2 = 0.77) and HCO3− (R2 = 0.77) concentrations are largely explained by the geology of the landmass, along with a negative correlation to annual precipitation, free CO2 concentrations were strongly linked to catchment macronutrient status. Overall, DIC dominates dissolved C inputs to coastal waters, meaning that estuarine carbon dynamics are sensitive to underlying geology and therefore are likely to be reasonably constant. In contrast, potential losses of carbon to the atmosphere via dissolved CO2, which likely constitute a significant fraction of net terrestrial ecosystem production and hence the national carbon budget, may be amenable to greater direct management via altering patterns of land use.

Plankton composition of Hakaluki Haor of Moulvibazar, Bangladesh

In the present study, physicochemical and biological variables related to the water quality of Hakaluki Haor were studied. Three study stations viz. Bakshimul, Jalabeel and Dudhai were investigated because of an event of mass scale of dead fish and other aquatic organisms were reported. The stations had water depths from 2.74 - 5.13 m and Secchi Disc Transparency were 0.74 - 1.91 m. The air and water temperature among the three stations ranged from 28.2 - 30.4°C and 21.8 - 28.8°C, respectively. TDS ranged from 35 - 42 mg/l, while the electric conductivity of water showed 40 - 50 μS/cm. SRP, nitrate and SRS ranged from 10.68 - 12.32 μg/l, 0.116 - 0.122 mg/l and, 16.08 - 35.42 mg/l, respectively. The concentration of DO was very poor which ranged from 2.8 - 5.4 mg/l. In all the three studied stations, the free CO2 concentration was 0.096 mg/l. Chlorophyll-a value was moderate in all the three stations (ranged within 34.67 and 40.60 μg/l). The phaeopigment concentration was low and ranged from 1.51- 8.72 μg/l among the studied stations. Concentration of ammonia was much higher (1.03 - 1.72 mg/l) than the standard value for Bangladesh (0.5 mg/l). From this analysis, it is observed that during fish kill event the concentration of ammonia was higher with low DO content which might have resulted because of the decomposition of upper foliar parts of the rice plant due to the sudden inundation. Gross α and β counts were found to be 0.01 and 0.10 Bq/l in the Haor water at the time of fish kill. From the planktonic community, 16 phytoplanktons from green algae, 14 euglenoids, 5 diatoms, 5 dinoflagellates and 12 zooplankton species were recorded. A shift in the pH of the Haor water from acidic to alkaline might have occurred during the last 3 decades. A detailed limnological study covering the climatic seasons of Bangladesh has been recommended to be carried out for Hakaluki Haor.
 Dhaka Univ. J. Biol. Sci. 30(1): 69-78, 2021 (January)

Effects of water quality on phytoplankton biomass in Balu river, Dhaka, Bangladesh

The Balu River is a peripheral river of Dhaka Metropolis and like other rivers its water quality is also highly vulnerable towards pollution. In the present study, effects of water quality parameters on the phytoplankton biomass have been studied for six climatic seasons of the year. The results obtained were compared with two other rivers of Dhaka Metropolis namely, Buriganga and Turag. Balu River showed water quality characters almost comparable with two other rivers. The phytoplankton biomass as chlorophyll a (chl-a) was found to be correlated directly with air and water temperature and alkalinity of the water. However, a weak positive correlation was obtained between chl-a and Secchi depth and free CO2 concentration. Nitrate nitrogen showed weak negative correlation with chl-a and phaeopigment and phytoplankton total density. High fluctuation was observed in the concentration of DO (0.20 - 4.50 mg/l) and free CO2 (0.06 - 2.90 mg/l) throughout the seasons. Soluble reactive phosphorus ranged from 30 - 1248 μg/l and chl-a ranged from 6.77 - 32.60 μg/l. Phytoplankton density ranged 1178 - 7409×103 ind./l over the study year. Water color ranged from light blue to dark black. The depth of visibility as Secchi depth varied from 15.24 - 81.28 cm whilst the water depth of the studied station Paschim Gaon of Balu River ranged from 4.57 - 7.92 m. Air and water temperature ranged from 25.4 - 36.5°C and 23.4 - 32.3°C, respectively.
 J. Biodivers. Conserv. Bioresour. Manag. 2020, 6(1): 37-46

Elevated co2 has Differential Effects on Five Species of Microalgae from a Subtropical Freshwater Lake: Possible Implications for Phytoplankton Species Composition.

Rising atmospheric CO2 concentrations are predicted to have a significant impact on global phytoplankton populations. Of particular interest in freshwater systems are those species that produce toxins or impact water quality, though evidence for how these species, and many others, will respond is limited. This study investigated the effects of elevated CO2 (1,000ppm) relative to current atmospheric CO2 partial pressures (400ppm), on growth, cell size, carbon acquisition, and photophysiology of five freshwater phytoplankton species including a toxic cyanophyte, Raphidiopsis raciborskii, from Lake Wivenhoe, Australia. Effects of elevated CO2 on growth rate varied between species; notably growth rate was considerably higher for Staurastrum sp. and significantly lower for Stichococcus sp. with a trend to lower growth rate for R.raciborskii. Surface area to volume ratio was significantly lower with elevated CO2 , for all species except Cyclotella sp. Timing of maximum cell concentrations of those genera studied in monoculture occurred in the lake in order of CO2 affinity when free CO2 concentrations dropped below air equilibrium. The results presented here suggest that as atmospheric levels of CO2 rise, R.raciborskii may become less of a problem to water quality, while some species of chlorophytes may become more dominant. This has implications for stakeholders of many freshwater systems.

Comparative analysis of physico-chemical parameters of some river systems of Ebonyi State, Nigeria

The study comparatively analyzed the general physico-chemical parameters of five different water bodies to assess their suitability for fish production. Four water bodies (Enyigba, Mkpuma, Ameka and Ebonyi) close to quarry sites were selected while the fifth was a culture pond water which served as the control experiment. The water parameters: pH, temperature, dissolved oxygen (DO), free CO2 and transparency were examined using standard methods for 24 months. The results showed that the pattern of temperature variation in all the water bodies examined followed a similar trend with the lowest value observed between December and January. The pond water showed slightly varied pH levels compared to the natural water bodies. The DO contents of Ebonyi, Mkpuma and Enyigba were higher than those recorded from Ameke and pond. Relatively, lower concentrations of free CO2 were recorded in the pond water and Ebonyi river during the harmattan period (December to January) and below the detectable levels. The variation of Sechi disc depth was higher in Enyigba when compared with other water bodies all through the period of the experiment. The trend of transparency was the same in all the water bodies.
 Keywords: Physico-chemical parameters, natural water bodies, pond water, fish production, Ebonyi State

Structure and function of an inorganic carbon transporter that captures CO2 in green algae.

Structure and function of an inorganic carbon transporter that captures CO2 in green algae.

Phytoplankton in relation to water quality of Tanguar Haor ecosystem, Bangladesh: 2. Watch tower station

Phytoplankton biomass in relation to some environmental and nutritional parameters at Watch Tower Station of Tanguar and Rauar Station has been studied. Since the Haor is a Ramsar Site, it is a globally important aquatic ecosystem. In the present investigation, the structure of the phytoplankton and the water quality factors were worked out and the data were compared Rauar Station with having the same ecosystem. Though weaker, a difference among alkalinity, total dissolved solids (TDS), conductivity, dissolved oxygen (DO), Secchi disc transparency, soluble reactive phosphorous (SRP), soluble reactive silicate (SRS), NO3-N, NH4+, chlorophyll-a and phytoplankton population density was found between the Watch Tower and the Rauar Station of Tanguar Haor. The mean values of the aforsaid parameters were found to some extent higher in the Watch Tower Station. The Watch Tower Station was deeper and perennial, where the depth of water varied from 3.0 - 9.5 m annually with a mean of 6.72 m. In the studied station, air and water temperature varied from 22.6 - 30.6 and 22.7 - 30.3°C, respectively. Water transparency ranged from 2.08 - 3.0 m. From December to March the pH remained 8.1-9.7 and alkalinity from 0.73 - 1.35 meq/l. However, from April to September these two parameters ranged from 7.5 - 7.7 and 0.33 - 1.35 meq/l, respectively. Dissolved oxygen (DO) and free CO2 concentration ranged from 2.5 - 6.09 and 0.084 - 0.087 mg/l, respectively. During April to September the Chlorophyll-a value ranged from 5.5 - 7.5 μg/l while the range of SRP was 24.23 - 30.05 μg/l during the same period. At the latter part of the study year i.e., during the dry period (December to March) those two parameters were relatively low in concentration. In April a high concentration of NH4+ (1380 μg/l) was reported from the haor, at other times this parameter ranged from 690 - 820 μg/l. The NO3-N ranged from 0.25 - 0.75 mg/l. High density of phytoplankton population (2690 ind./l) was reported at the time of high concentration of SRP (30.05 μg/l ) of the haor water. The chlorophyll-a value (7.5 μg/l) was also highest at that time. So, it could be said that SRP concentration in Tanguar haor has been playing a vital role in regulating the standing crop of phytoplankton. To find the variation on a spatial scale, the data of the present investigation were compared with another study station of the haor namely, Rauar Station. No significant difference was observed among the concentrations of different parameters. However, a slight increasing trend in the concentrations of DO, alkalinity, SRP, NO3-N, SRS, NH4+ and total phytoplankton density was observed in the Watch Tower Station compared to Rauar Station. Watch Tower Station is also relatively deeper with an improved light climate as it had been revealed by the mean value of the Secchi depth. The water quality of Tanguar Haor has been classified as mesotrophic.
 Dhaka Univ. J. Biol. Sci. 29(1): 9-18, 2020 (January)

Transcriptome Reveals the Rice Response to Elevated Free Air CO2 Concentration and TiO2 Nanoparticles.

Increasing CO2 levels are speculated to change the effects of engineered nanomaterials in soil and on plant growth. How plants will respond to a combination of elevated CO2 and nanomaterials stress has rarely been investigated, and the underlying mechanism remains largely unknown. Here, we conducted a field experiment to investigate the rice (Oryza sativa L. cv. IIyou) response to TiO2 nanoparticles (nano-TiO2, 0 and 200 mg kg-1) using a free-air CO2 enrichment system with different CO2 levels (ambient ∼370 μmol mol-1 and elevated ∼570 μmol mol-1). The results showed that elevated CO2 or nano-TiO2 alone did not significantly affect rice chlorophyll content and antioxidant enzyme activities. However, in the presence of nano-TiO2, elevated CO2 significantly enhanced the rice height, shoot biomass, and panicle biomass (by 9.4%, 12.8%, and 15.8%, respectively). Furthermore, the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that genes involved in photosynthesis were up-regulated while most genes associated with secondary metabolite biosynthesis were down-regulated in combination-treated rice. This indicated that elevated CO2 and nano-TiO2 might stimulate rice growth by adjusting resource allocation between photosynthesis and metabolism. This study provides novel insights into rice responses to increasing contamination under climate change.

Aquatic plant diversity and physicochemical characteristics of headwater stream Bal Ganga, Garhwal Himalaya

The headwater stream Bal Ganga is a famous perennial, snow-fed tributary of the River Bhilangana. It emanates from the Khatling glacier and then mixed with the Dharam Ganga in Chamiyala and ultimately merges with the River Bhilangana in Muniprayag near the Ghansali town. The altitudinal gradient of Bal Ganga stream is not very high. The total basin reflects a network of various streams, rivulets of various dimensions beautifully representing a dendritic drainage or river system pattern. A total of three sites were identified for the collection of water samples in the study area. Analysis of physicochemical profile of mountain fluvial system of Bal Ganga had been undertaken for a time span of 12 months during October, 2016 to September, 2017. A total of thirteen physicochemical parameters were recorded during the study period. The water velocity was recorded between 0.47 and 2.24 m s−1. Hydro median depth was recorded within a range of 3.14–4.89 m. Total dissolved solids were found within a range of 84.3–101.1 mg l−1. Turbidity was found between 10.3 and 27.3 NTU. The concentration of dissolved oxygen was recorded within a range of 7.06–11.6 mg l−1. Concentration of free CO2 was recorded within a range between 2.2 and 13.2 mg l−1. Concentration of chlorides was recorded within a range between 2.84 and 9.66 mg l−1, and hardness concentration was recorded within a range of 14–28 mg l−1. A total of 15 species from two major groups of phytoplanktons and periphytons were identified that were Cocconeis, Cymbella, Diatoma, Fragilaria, Gomphonema, Navicula, Nitzschia, Synedra, Tabellaira, Cosmarium, Ulothrix, Spirogyra, Zygnema, Chlamydomonas and Cladophora.

Estimation and impact of carbon dioxide capture on drinking water: Tillmans equilibrium diagram

Abstract The increase of CO2 in the atmosphere may produce some effects on drinking water because water tends to naturally capture CO2 species. The main purpose was the study of the impact of capture of free CO2 and its transformation to carbonic acid (H2CO3) and bicarbonate ions (HCO−3). The study used a Tillmans equilibrium diagram obtained from the modified Mojmir Mach model as a function of water temperature and considered the effects on anion and cation composition. Three wells located in different zones were selected, with similar characteristics (capture of CO2). Samples were taken in different seasons of the year and the amount of CO2 in the drinking water was calculated. It was found that with increasing concentrations of free CO2 the pH decreases, and this process makes the water acid and susceptible to dissolve some elements (Ca, Na, K, Si) and other species (HCO−3). The capture of CO2 has important effects on the anion and cation composition of drinking water and on the variation of pH by more than one unit, which may affect the health of consumers. The method presented in this study is an excellent user-friendly alternative to determine the impact of natural capture of total CO2 by water.

Nontuberculous mycobacteria in the environment of Hranice Abyss, the world's deepest flooded cave (Hranice karst, Czech Republic).

Nontuberculous mycobacteria (NTM) are widely distributed in the environment. On one hand, they are opportunistic pathogens for humans and animals, and on the other hand, they are effective in biodegradation of some persistent pollutants. Following the recently recorded large abundance of NTM in extreme geothermal environments, the aim of the study was to ascertain the occurrence of NTM in the extreme environment of the water zone of the Hranice Abyss (HA). The HA mineral water is acidic, with large concentrations of free CO2, and bacterial slimes creating characteristic mucilaginous formations. Both culture and molecular methods were used to compare the mycobacterial diversity across the linked but distinct ecosystems of HA and the adjacent Zbrašov Aragonite Caves (ZAC) with consideration of their pathogenic relevance. Six slowly growing NTM species (M. arupense, M. avium, M. florentinum, M. gordonae, M. intracellulare) and two rapidly growing NTM species (M. mucogenicum, M. sediminis) were identified in the water and in the dry zones at both sites. Proteobacteria were dominant in all the samples from both the HA and the ZAC. The bacterial microbiomes of the HA mineral water and HA slime were similar, but both differed from the microbiome in the ZAC mineral water. Actinobacteria, a phylum containing mycobacteria, was identified in all the samples at low proportional abundance. The majority of the detected NTM species belong among environmental opportunistic pathogens.

Cylindrospermopsis raciborskii and Microcystis aeruginosa competing under different conditions of pH and inorganic carbon

Based on the fact that the intense photosynthetic activity of blooms causes a marked decrease in free CO2 concentrations and increase in pH of the water, the aim of the present study was to investigate the competitive relationship between Cylindrospermopsis raciborskii and Microcystis aeruginosa under different pH and inorganic carbon conditions. Our hypothesis is that C. raciborskii is a better competitor than M. aeruginosa in alkaline pH and when bicarbonate (HCO3−) is the main source of carbon. Semi-continuous cultures were conducted in a factorial experiment with three different pH conditions (free [unbuffered], 6.8 and 8.2), with and without aeration, and with and without the addition of a bicarbonate source. Both species demonstrated a good performance under high pH, but the interaction between the factors determined significant differences in the competitive responses of the C. raciborskii and M. aeruginosa strains, with a change in dominance in the different scenarios. Whilst C. raciborskii was favoured by aeration, the addition of bicarbonate improved the growth of M. aeruginosa. The results suggest that affinity and efficiency in bicarbonate use may be a determinant of dominance and competitive success in potentially toxic cyanobacteria, such as the genus Microcystis.

Taxonomic and functional classifications of phytoplankton in tropical reservoirs with different trophic states

Ecological approaches, such as functional groups (sensu Reynolds, FG) and exclusively morphological-based groups (sensu Kruk, MBFG), have provided a reliable tool for understanding phytoplankton responses to environmental conditions. Our study evaluated the concordance and the response of these two-functional classifications of the phytoplankton community to environmental variables in reservoirs of different trophic states (ultra-oligotrophic to meso-eutrophic). We also investigated the spatial and temporal concordance of the functional classifications with the taxonomic-based classification (species). Integrated water samples were collected in the euphotic zone in two climatic periods (summer and winter) to determine physical and chemical variables and phytoplankton. Higher water temperature and thermal stratification were observed in the summer, whereas higher free CO2 concentrations and mixing regime of water column in the winter. The 35 descriptors species showed a greater relationship to the trophic conditions of the reservoirs. The functional classifications revealed that the 17 FGs and 7 MBFGs were influenced primarily by seasonal variation of limnological conditions (water temperature, CO2 concentration, Zmix depth) and secondarily by trophic state of the reservoirs. Stronger similarity (higher than 0.70) was verified between species and FGs matrices (Mantel test, mainly) than between species and MBFGs ones. Procrustes and Mantel tests also evidenced high concordance between FGs and MBFGs matrices, exhibiting similar spatial and temporal distribution to environmental conditions. Thus, these ecological classifications demonstrated to be complementary tools, besides their particular degrees of detailing, to elucidate the functional responses of numerous phytoplankton species in studied tropical reservoirs.

Carbon dioxide and submersed macrophytes in lakes: linking functional ecology to community composition.

Evaluating plant community response to atmospheric CO2 rise is critical to predicting ecosystem level change. Freshwater lakes offer a model system for examining CO2 effects as submersed macrophyte species differ greatly in their growth responses to CO2 enrichment, and free CO2 concentrations among these habitats show a wide range of natural, spatial variation. We determined free CO2 concentrations in the water column and sediment porewater in littoral zones with pH<6.0 in Adirondack Mountain (New York, USA) lakes, and derived a community CO2 responsiveness index (CCRI) based on quantitative sampling of 15 submersed macrophyte communities coupled with greenhouse-derived growth responses to CO2 enrichment of constituent species to test two hypotheses: (1) CCRI, which is higher for communities dominated by species with greater growth responses to CO2 enrichment, is positively correlated to free [CO2 ] in the water column, and (2) in natural communities, the percent of sediment CO2 -using species, which are relatively unresponsive to CO2 enrichment, is negatively correlated to free [CO2 ]. A significant positive correlation (P=0.003) between our physiologically based CCRI and the concentration of free CO2 in the water column supported our primary hypothesis that sites with higher levels of free CO2 are dominated by species with greater growth responses to CO2 enrichment. Our CCRI is also highly significantly correlated (P<0.001) to the first axis scores for the same vegetation data from polar ordination. Finally, the relative importance of species that use sediment CO2 as a photosynthetic carbon source is significantly negatively correlated (P=0.029) with the concentration of free CO2 in the water column. Our results indicate that natural variations in CO2 levels are important determinants of submersed macrophyte community composition. Further, we demonstrate the utility of a physiologically-based index of community composition, our CCRI, as an ecologically valid measure of community response to CO2 .

Study of Physico-Chemical Parameter of Deepang lake in Pokhara Valley, Nepal

The present study on Physico-chemical Parameter of Deepang lake in Pokhara valley, Nepal was performed for six months from August 2009 to January 2010. The study included various physico-chemistry parameter like transparency, temperature, PH, free carbondioxide, dissolve oxygen and total alkalinity. The maximum transparency 2.5 m was recorded in January and minimum 1.4 m in August. In other months the transparency were slightly changeable. The maximum temperature 25.6°C was recorded in August and minimum 17.7°C in January. The temperature gradually decreased. The PH values were found mostly alkaline and were generally between 6.7 and 7.5 during the investigation period. The highest PH 7.5 was recorded in January and lowest 6.7 in August. Dissolved oxygen value gradually increased from 6.4 mg/l in August to 8.7 mg/l in January. The concentration of free CO2 ranged between 1.8 mg/l and 5.6 mg/l during the investigation period. The maximum value was 5.6 mg/l in August and 1.8 mg/l in January. The maximum alkaline value 114 mg/l was recorded in January and minimum value 105 mg/l in August. All these Physico-chemical parameter meet WHO Standard of Water Quality. Janapriya Journal of Interdisciplinary Studies Vol. 2, No.1 (December 2013), page: 90-95