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Renewable Energy in the Context of Sustainable Development

Effects of a thermal discharge from a nuclear power plant on phytoplankton and periphyton in subtropical coastal waters

Progression of biofilm formation was monitored at two stations near a nuclear power plant, Kalpakkam, located near coastal waters of Bay of Bengal. These stations are natural marine environment, station 1; and the condenser outfall area of the power plant the modified marine environment station 2. The biofilm formed on plexiglas panels was analysed in triplicates at 24 h intervals for various physical, chemical and biological parameters for 120 h (5 days). The biofilm formation showed both temporal and spatial variation in various parameters assayed. Among the water-quality parameters analysed, seawater temperature showed significant increase (~5°C) at station 2. The increase in water temperature enhanced the metabolism and influenced most of the biofilm parameters assayed at station 2. Biofilm formed at station 2 was very thick (113 μm) than that of at station 1 (22 μm). The distribution of parameters like biofilm thickness, biomass, chlorophyll a, particulate organic carbon, hexose sugar and diatom counts showed similar trend (i.e., a sharp increase after 96 h of biofilm growth) in the biofilm formed at station 2. Moderately high ammonia levels (44 μg l−1) were detected in the biofilm formed at station 2. The biofilm microbiota was diverse at both the stations: it constituted bacteria [nitrate reducers (NRB), ammonia oxidizers (AOB) and culturable aerobic heterotrophic bacteria (CAHB)], algae and macrofoulants. The various bacterial types assayed showed a population range from 102 to 106 cfu cm−2. The final community after 120 h at station 1 comprised CAHB, NRB, diatoms, barnacle cyprids and juvenile bryozoans. At station 2, the biofilm initially consisted of CAHB, NRB and diatoms but after 120 h, AOB, cyanobacteria and filamentous algae were dominant. The plausible factors that influenced biofilm formation were temperature, nutrients and organic matter. The biofilm phenomenon in natural and modified marine environment was hypothesized and discussed.

Comparative effect of temperature on biofilm formation in natural and modified marine environment

study, which varied between 1.7 x 10 5 and 1.5 x 10 6 cells l -1 . Another important feature of this study was the observation of Trichodesmium erythraeum bloom in the coastal waters. Concomitant with the bloom, a drastic fall in the number of phytoplankton species was noticed. The change in phytoplankton assemblages (density and species composition) during different seasons was significant and was found to be regulated by the change in water characteristics associated with monsoon. Diatoms dominated the phytoplankton assemblage followed by dinoflagellates. Asterionellopsis glacialis and Thalassionema nitzschioides were found to be dominant species among diatoms and dinoflagellates respectivaly, Prorocentrum micans and Protoperidinium sp. were the dominant forms. Salinity was found to be an important parameter influencing the species composition, standing stock and succession of phytoplankton at this location. Salinity apparently influenced the phytoplankton density positively. Nitrate was found to be the limiting factor for phytoplankton growth during late summer and pre-monsoon periods, whereas, the role of silicate and phosphate remained insignificant in this regard.

/pdf/variations-in-community-structure-of-phytoplankton-in-38k8hla14q.pdf

Variations in community structure of phytoplankton in relation to physicochemical properties of coastal waters, southeast coast of India

In ecotoxicological studies involving environmental contaminants, rapid and multi-parametric optical detection based methods have definite advantages over traditional growth inhibition assays. In this context, a confocal laser scanning microscopy (CLSM) based method to assess ecotoxicity arising out of biocide insult to marine microalgae is reported. Using this technique, the effect of in-use concentrations of chlorine (an oxidizing biocide) on a marine diatom (Cocconeis scutellum Ehrenb) was determined based on inhibition of chlorophyll autofluorescence and esterase activity (probed by fluorescein diacetate (FDA) staining). Determination of mean fluorescence intensity (MFI) per cell by collecting auto-fluorescence from single cells in x, y and z dimensions permitted reproducible toxicity evaluation at single-cell level. Chlorine-induced inhibition of autofluorescence in laboratory cultures was dose-dependent. Additional data on metabolic activity of the diatom cells following chlorine exposure was collec...

V.N.R. Rao

Papers

Impact of thermal discharge from a tropical coastal power plant on phytoplankton

Use of coastal waters as condenser coolant in electric power plants: Impact on phytoplankton and primary productivity

Phytoplankton growth under temperature stress: Laboratory studies using two diatoms from a tropical coastal power station site