823 resultados para Photometry


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In this monograph on the basis of materials obtained by the author and his colleagues in Arctic expeditions of 1991-2005 and of published data results of studies effect of aerosols on environmental conditions and marine sedimentation in the Arctic are summarizes. Processes of aeolian transport and transformation of sedimentary material from sources to places of its accumulation in bottom sediments are described. Results of this study can be used to assess current state of ecosystem of Arctic seas and as a background for evaluation of possible human impact on nature during exploration of mineral resources of the Arctic shelf. For oceanographers, geochemists, geoecologists.

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The dataset provides detailed information on the study that was conducted in Lahore's 7 major towns. The sample was taken from 472 tubewells and analyzed for major cations and anions using APHA 2012 techniques as explained herein. Besides, E.coli determination was done to check for microbial contamination. The data includes results from PHREEQC modeling of As(III)/ As(V) species and saturation indices as well as Aquachem's computed hydrochemical water facies. The WHO (2011) and EPA standards included in Aquachem identified the parameters that where in violation. Bicarbonates dominated the groundwater types with 50.21% of the samples exceeding the EPA maximum permissible limit of 250 mg/L in drinking water. Similarly, 30.51% of the samples had TDS values greater than 500 mg/L while 85.38 % of the samples exceed 10 µg/L threshold limit value of arsenic. Also, instances of high magnesium hazard values were observed which requires constant assessment if the groundwater is used for irrigation. Higher than 50% MH values are detrimental to crops which may reduce the expected yields. The membrane filtration technique using m-Endo Agar indicated that 3.59% samples had TNC (too numerous to count) values for E.coli while 5.06% showed values higher than 0 cfu/ 100 ml acceptable value in drinking water. Any traces of E-coli in a groundwater sample indicate recent fecal contamination. Such outcomes signify presence of enteric pathogens. If the groundwater is not properly dosed with disinfectants it may cause harm to human health. It is concluded that more studies are needed and proper groundwater management implement to safeguard the lives of communities that depend solely on groundwater in the city.

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A new microtiter-plate dilution method was applied during the expedition ANTARKTIS-XI/2 with RV Polarstern to determine the distribution of copiotrophic and oligotrophic bacteria in the water columns at polar fronts. Twofold serial dilutions were performed with an eight-channel Electrapette in 96-wells plates by mixing 150 µl of seawater with 150 µl of copiotrophic or olitrophic Trypticase-Broth, three times per well. After incubation of about 6 month at 2 °C, turbidities were measured with an eight-channel photometer at 405 nm and combinations of positive test results for three consecutive dilutions chosen and compared with a Most Probable Number table, calculated for 8 replicates and twofold serial dilutions. Densities of 12 to 661 cells/ml for copiotrophs, and 1 to 39 cells/ml for oligotrophs were found. Colony Forming Units on copiotrophic Trypticase-Agar were between 6 and 847 cells/ml, which is in the same range as determined with the MPN method.

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Results of geological research carried out by V.I. Il'ichev Pacific Oceanological Institute (Far East Division of the Russian Academy of Sciences) and P.P. Shirshov Institute of Oceanology (Russian Academy of Sciences) on the submarine Vityaz Ridge during Cruise 37 of R/V Akademik Lavrentyev in 2005 are discussed. Various rocks composing the basement and the sedimentary cover of the ridge were dredged in three areas. Based on isotope geochronology, petrogeochemical, petrographic, and paleontological data and comparison with similar rocks available from the adjacent land and the Sea of Okhotsk, they are subdivided into several age complexes. Late Cretaceous, Eocene, Late Oligocene, Miocene, and Pliocene-Pleistocene complexes are defined among igneous rocks, while volcanogenic-sedimentary rocks are united into Late Cretaceous - Early Paleocene (Late Campanian - Danian), undivided Paleogene (Paleocene-Eocene?), Oligocene - Early Miocene, and Pliocene-Pleistocene complexes. Obtained data on age and formation settings of the defined complexes allowed to reconstruct geological evolution of the central Pacific slope of the Kurile Island arc.

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Study sites. Samples of surface water were taken from 4 coastal lagoons on the Yucatan Peninsula in Mexico: Celestun (20° 45' N - 90° 22' W), Chelem (21° 15' N - 89° 45' W), Rosada Lagoon (21º 19' N - 89º 19' W), and Sabancuy Estuary (18° 58' N - 91° 12' W). The sampling was performed from august to October of 2011 (Chelem 08/24; Laguna Rosada 09/06; Celestún 09/28; Sabancuy 10/25). The sampling was random without replacement and 10 samples of surface water were collected along a transect parallel to the coastal axis. Samples were deposited in sterile plastic bottles and conserved in refrigeration at 4°C. All samples were processed within 24 hours after sampling. According to the Mexican laws and regulations no permissions are required to obtain water and sediment samples from open public areas. Analysis of environmental and physicochemical parameters. Determinations of the environmental parameters were performed with a Hach 5465000 model 156 multi-parameter measuring instrument. The Lorenzen method was used to determine chlorophyll-a (21) with 90% acetone and the concentration was calculated according to the formula: Chla= 27.63 (OD665o - OD665a)(VA)/VM x L Where, OD665o: absorbance at 665 nm before acidification; OD665a: absorbance at 665 nm after acidification; VA: volume (ml) of acetone for extraction; VM: volume (ml) of filtered water; L: length (cm) of the photometric cell. Determinations of the physicochemical parameters (silicates, phosphates, nitrates, nitrites and ammonia) were performed using the spectrophotometric techniques described and modified by Strickland and Parsons (1972).

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A study of chemical and isotopic composition of coastal thermal springs and waters of the Kraternaya Bay, Yankicha Island, revealed that the total mineralization and concentrations of d18O and d2H decrease from the thermal spring site I to V. These waters are of marine origin with various proportions of local meteoric water. Thermal waters of the site VI have considerably altered chemical and isotopic composition due to high temperatures of surrounding rocks. Base temperatures calculated for this area were 130-200°C. Coastal thermal springs affect isotopic composition of water throughout the bay.

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Concentrations of sulfide, S°, and thiosulfate were determined in waters of the Baltic Sea. Microquantities of these compounds were observed in oxic waters. Concentration levels of reduced sulfur compounds in Baltic oxic waters were very close to levels of the Black Sea oxic zone. Thiosulfate and S° were predominate compounds in oxic water whereas sulfide was a predominant compound of Baltic waters high in hydrogen sulfide. Conclusion was made that during sedimentation in oxic waters anaerobic microorganisms along with aerobic bacteria take part in mineralization of organic matter. They exist on surfaces and in microniches of particles of organic detritus.

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The main stages of the sedimentary cycle of uranium in modern marine basins are under consideration in the book. Annually about 18 thousand tons of dissolved and suspended uranium enters the ocean with river runoff. Depending on a type of a marine basin uranium accumulated either in sediments of deep-sea basins, or in sediments of continental shelves and slopes. In the surface layer of marine sediments hydrogenic uranium is predominantly bound with organic matter, and in ocean sediments also with iron, manganese and phosphorus. In diagenetic processes there occurs partial redistribution of uranium in sediments, as well as its concentration in iron-manganese, phosphate and carbonate nodules and biogenic phosphate detritus. Concentration of uranium in marine sediments of various types depending on their composition, as well as on forms of its entering, degree of differentiation and of sedimentation rates, on hydrochemical regime and water circulation, and on intensity of diagenetic processes.

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Four strains of the coccolithophore E. huxleyi (RCC1212, RCC1216, RCC1238, RCC1256) were grown in dilute batch culture at four CO2 levels ranging from ~200 µatm to ~1200 µatm. Growth rate, particulate organic carbon content, and particulate inorganic carbon content were measured, and organic and inorganic carbon production calculated. The four strains did not show a uniform response to carbonate chemistry changes in any of the analysed parameters and none of the four strains displayed a response pattern previously described for this species. We conclude that the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis. We propose that this can explain apparently contradictory results reported in the literature.