Hydrogeochemical characterization of fluoride rich groundwater of Wailpalli watershed, Nalgonda District, Andhra Pradesh, India

The groundwater of Nalgonda district is well known for its very high fluoride content for the past five decades. Many researchers have contributed their scientific knowledge to unravel causes for fluoride enrichment of groundwater. In the present paper, an attempt has been made to relate the high fluoride content in the groundwater to hydrogeochemical characterization of the water in a fracture hard rock terrain—the Wailpally watershed. Groundwater samples collected from all the major geomorphic units in pre- and post-monsoon seasons were analyzed for its major ion constituents such as Ca^2?+?, Mg^2?+?, Na^?+?, K^?+?, CO $_{3}^{-}$ , HCO $_{3}^{-}$ , Cl^???, SO $_{4}^{-2}$ , NO $_{3}^{-}$ , and F^???. The groundwaters in the watershed have the average fluoride content of 2.79 mg/l in pre-monsoon and 2.83 mg/l in post-monsoon. Fluoride concentration in groundwater does not show perceptible change neither with time nor in space. The ionic dominance pattern is in the order of Na^?+? > Ca^2?+??> Mg^2?+??> K^??? among cations and HCO $_{3}^{-}\:\,>$ Cl^????> SO $_{4}^{-2} >$ NO $_{3}^{-} >$ F^??? among anions in pre-monsoon. In post-monsoon, Mg replaces Ca^2?+? and NO $_{3}^{-}$ takes the place of SO $_{4}^{-2}$ . The Modified Piper diagram reflect that the water belong to Ca^?+?2–Mg^?+?2–HCO $_{3}^{-}$ to Na^?+?–HCO $_{3}^{-}$ facies. Negative chloralkali indices in both the seasons prove that ion exchange between Na^?+? and K^?+? in aquatic solution took place with Ca^?+?2 and Mg^?+?2 of host rock. The interpretation of plots for different major ions and molar ratios suggest that weathering of silicate rocks and water–rock interaction is responsible for major ion chemistry of groundwater in Wailpally watershed. Chemical characteristics and evolution of this fluoride-contaminated groundwater is akin to normal waters of other hard rock terrain; hence, it can be concluded that aquifer material play an important role in the contribution of fluoride in to the accompanying water. High fluoride content in groundwater can be attributed to the continuous water–rock interaction during the process of percolation with fluorite-bearing country rocks under arid, low precipitation, and high evapotranspiration conditions.     

The effects of salinity,temperature and sediment on the toxicity of copper to juvenile Hediste (Nereis) diversicolor (O. F. Muller)

Without sediment, increasing salinity (7.3 to 29.2) and increasing temperature (12 to 22 °C) reduced the toxicity of copper to juvenile Hediste diversicolor. The LC₅₀ values ranged from 357 gL^-1 in 7.3 to 513 g L^-1 in 29.2 at 12°C and from 247 to 500 g L^-1 at 22°C. In deionized water all the juvenile were dead in all solutions to which copper was added (100 to 600 g L^-1). Dead worms were swollen and everted their pharynxs. In higher doses of copper (500 to 600 g L^-1) the worms were abnormal in behaviour in all salinities (0 to 29.2). The ability to swim or crawl was disturbed.With sediments increasing temperature and increasing salinity increased the toxicity of copper to the worms. The LC₅₀ values ranged from 3200 to 4100 g L^-1 at 22°C. The response of the juvenile to copper was antagonistic to increasing temperature and salinity and synergistic to increasing salinity and increasing temperature without and with the sediment respectively.     

The effect of temperature and salinity on copper body-burden and copper toxicity to Hediste (Nereis) diversicolor

Temperature from 12 to 22°C and salinity from 30.5 to 7.6 increased accumulation of copper in Hediste diversicolor. Copper accumulated ranged from 85.83 to 217.14 g g^-1. Sediments reduced accumulation of copper under temperature-salinity combinations. Accumulated copper ranged from 90.19 to 153.26 g g^-1.However, mortality of the worms was not solely dependent upon copper body-burden. It ranged from 34 to 45% and from 38 to 80% in the presence of sediment. A combination of osmoregulatory and thermal stresses increased the toxic effect of copper to the worms.     

A model for the maximum credible hourly impact on any ground receptor from point sources with momentumdominated plume rise

A pollutant dispersion model is developed, allowing rapid evaluation of the maximum credible one-hour-average concentration on any given ground-level receptor, along with the corresponding critical meteorological conditions (wind speed and stability class) for stacks with momentum-dominated plume rise in urban or rural areas under buoyancy or no buoyancy induced dispersion. Site-specific meteorological data are not required, as the computed concentrations are maximized against all credible combinations of wind speed, stability class, and mixing height.The analysis is based on the dispersion relations of Pasquill-Gifford and Briggs for rural and urban settings respectively, the buoyancy induced dispersion correlation of Pasquill, the wind profile exponent values suggested by Irwin, the momentum plume rise relations of Briggs, as well as the Benkley and Schulman's model for the minimum mixing heights.The model is particularly suited for air pollution management studies, as it allows fast screening of the maximum impact on any selected receptor and evaluation of the ways to have this impact reduced. Also, for regulatory purposes, as it allows accurate setting of minimum stack height requirements as function of the exit gas volume and velocity, the pollutant emission rates and their hourly concentration standards, as well as the source location relative to sensitive receptors.     

Observations on the geographic variation of the marine coastal fish Spinachia spinachia

Spinachia spinachia L., the fifteen-spined or sea stickleback, is a little known annual fish widely distributed throughout European coastal waters. Although known to be morphologically variable, no studies of the extent or patterns of population differentiation had as yet been undertaken. Investigation of over 30 well-scattered samples revealed meristic differences which correlate well with breeding season temperatures. This relationship is probably complex, for although temperature changes linearly, meristic counts showed evidence of a V-shaped (or curvilinear) pattern. Comparison with studies on other European stickleback species suggests that selection rather than phenetic induction has produced this trend in variation. Some information on the diet of this species is also presented.     

Studies on 14CO2-assimilation in marine rhodophyceae

Experiments on enzymatic (in vitro) and in vivo CO₂-fixation using a variety of marine Rhodophyceae such as Porphyra umbilicalis (L.) J.Ag., Rhodomela confervoides (Huds.) Silva, Corallina officinalis L. and Chondrus crispus Stackh. revealed that carbon assimilation in the Rhodophyceae is almost exclusively performed by photosynthesis via ribulose-1, 5-di-phosphate carboxylase, whereas light-independent CO₂-fixation via -carboxylation by phosphoenolpyruvate carboxykinase scarcely exceeds 1% of the total carbon fixation potential of the plants. Activity of phosphoenolpyruvate carboxylase could not be detected. With respect to the main accumulation products of photosynthetic CO₂-fixation, the Rhodophyceae investigated are not uniform: Corallina officinalis L., Rhodymenia palmata (L.) Grev., and Gigartina stellata (Stackh.) Batt. have been found to accumulate ¹⁴C in the neutral compound floridoside (=2-O-glycerol--D-galactopyranose), whereas Delesseria sanguinea (Huds.) Lamour., Ceramium cubrum (Huds,) C.Ag., and Rhodomela confervoides (Huds.) Silva, representing members of the Delesseriaceae, Ceramiaceae and Rhodomelaceae, respectively, do not photosynthesize floridoside, but show intense ¹⁴C-labelling in an acidic constituent, mannosidoglycerate (= digeneaside). This compound is reported for the first time as a rapidly ¹⁴C-labelled and accumulated photosynthate in a variety of red algal species exclusively belonging to the Ceramiales.     

Lysosomal responses to experimentally injected anthracene in the digestive cells of Mytilus edulis

Experimentally injected anthracene (10 to 100 g mussel^-1) has been shown to induce dose-dependent lysosomal destabilisation and release of hexosaminidase in the digestive cells of Mytilus edulis after 24 h. This destabilisation was accompanied by cytological evidence of cytolysis of the digestive cells. The destabilising effect of 100 g of injected anthracene persisted for 96 h with a return to the control condition by 168 h. These results are discussed in the context of environmental contamination by polycyclic aromatic hydrocarbons.     

Feeding rate and duration of daily activity of Astropecten aranciacus (Echinodermata: Asteroidea) in relation to prey density

In a feeding experiment, 16 individuals of Astropecten aranciacus were kept in two enclosures on the sea floor, and were provided with a surplus of food. Feeding at a daily rate of 1.3% of their dry tissue weight, their food intake was four times higher than that of free-living sea stars. The periods of daily activity were shorter than in control individuals kept in enclosures without additional food.     

Benthic invertebrate assemblages of Delaware Bay

During two consecutive summers, the first quantitative bay-wide survey (207 stations) of benthic invertebrates was conducted in Delaware Bay (USA). In 1972, 109 species were collected at 105 stations; and in 1973, 125 species were collected at 102 stations. A total of 169 different species were collected for both summers. The number of species and number of individuals increased with increasing salinity and increasing median grain size. These relationships were compared and were found similar to those in estuaries and bays throughout the world. Average density was 722 individuals m², which is low compared to other estuaries. The relationship of low secondary production to pollution, macroscopic algae, sediment transport, predation, and hydrography is discussed. Deposit feeders comparised the major feeding type. Local species composition was similar to that in Chesapeake Bay, and dominant species occurred in estuaries throughout the Mid-Atlantic Bight. The benthic invertebrates of Delaware Bay were related to the cosmopolitan mode of estuarine faunas. Faunal assemblages were identified by cluster analysis. The assemblages were associated with sediment type and salinity. It was concluded that Delaware Bay comprises a mosaic of animal assemblages, some of which have relatively sharp boundaries similar to classical level bottom type communities, whereas the boundaries of others are almost impossible to detect, and these represent species distributed along an environmental continum.     

Composition biochimique des copépodes de l'hyponeuston de Méditerranée Nord occidentale. Poids sec et analyse élémentaire du carbone,de l'hydrogène et de l'azote

Dry weight, total carbon, hydrogen and nitrogen contents were studied in Anomalocera patersoni, Pontella mediterranea, P. lo biancoï and Labidocera wollastoni as a function of sex and developmental stage. 629 individuals were analysed over the year. Protein content was calculated from the nitrogen values, and results are presented as percent dry weight. C:H and C:N ratios were also determined. The lowest contents of carbon (32.4%) and nitrogen (9.3%) were determined for female L. wollastoni, the highest carbon content (43.3%) for female P. lo biancoï, and the highest nitrogen content (11.5%) for female P. lo biancoï and male A. patersoni. This range agrees with the data in the literature for marine copepods. According to available data on biochemical composition of zooplankton in relation to depth, the Pontellidae contain a high amount of proteins. The carbon:nitrogen ratio displays great stability within a species, indicating a constant elementary composition during development from copepodite to adult. Nevertheless, there is a statistically significant discrepancy between the C:N ratios for A. patersoni and P. mediterranea which is due to a higher rate of increase in carbon content in A. patersoni. As a whole, interspecific variations were small (C:N ranged between 3.4 and 3.8) compared to those recorded in true planktonic species. This appears to be an important characteristic of the Pontellidae, in contrast with other, more widely distributed copepods, and probably is related to the peculiarities of their biotope, the ultrasuperficial layer.