71 resultados para chemical profiling


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This report contains results from the second cruise of the Modis Optical Characterization Experiment (MOCE). Data presented here were obtained on the Mexican Research Vessel El Puma between 29 March and 13 April along the Pacific coast of Baja California and in the Gulf of California. Three types of data are reported: high spectral resolution radiometry at three depths for 13 stations; salinity, temperature beam attenuation and chlorophyll-a fluorescence, profiles at the same stations; and total suspended matter and suspended organic carbon and nitrogen.(PDF is 90 pages.)

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This report contains CTD profiling results from the seventh cruise to the Marine Optics Buoy (MOBY) site near the Island of Lanai. Data presented here were obtained on the University of Hawaii Research Vessel Moana Wave between 26 and 30 June 1994. Two types of data are reported: vertical profile observations of salinity, temperature beam attenuation and chlorophyll-a fluorescence, profiles; and total suspended matter and suspended organic carbon and nitrogen taken from water samplers at those stations.

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This report contains results from the third cruise of the Marine Optical Characterization Experiment (Fig. 1). A variety of spectroradiometric observations of the upper water column and atmosphere were made by investigators from the University of Miami, NOAA, CHORS and MLML. Data presented here were obtained by oceanographic CTD profiler: salinity, temperatllre, dissolved oxygen, beam attenuation and chlorophyll-a fluorescence; and by water samplers: total suspended matter and suspended organic carbon and nitrogen, salinity, and dissolved oxygen.

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This study looks at the distribution and magnitude of acidification and eutrophication in south-east England where there are no natural lakes but a large number of shallow artificial ponds. The study area is defined as the region lying within a 100 km radius of central London but excluding the area within the M25 motorway. Water samples were taken from 120 sites between mid-January and the end of February 1990, with a subsequent monthly survey of a subset of 31 of these waters. Twelve chemical variables were measured in the laboratory using standard techniques. PH values for the full dataset ranged from 3.2 to 8.4, although the majority of sites had pH values in the range 7.0 to 8.5; only five sites had a pH of less than 6.0. The five low pH sites expectedly had low alkalinities and are the only sites with values below 0.1 meq per litre. Concentrations of calcium, sodium, potassium, magnesium, chloride, sulphate and nitrate had normal distributions. The majority of sites had total phosphorus concentrations in the range 25 to 200 mu g per litre, although 10 sites had concentrations above 400 mu g per litre. The low number of acid sites suggests that surface water acidity is not a widespread regional problem in south-east England. However the survey shows that a large number of standing waters in the region have high total phosphorus and nitrate concentrations, and 89% may be considered moderately to considerably eutrophic.

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This abbreviated translation summarises the chemical composition of Iraq water resources. Among the described water bodies are the River Euphrates, Shatt al Arab River and a number of standing waters.

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A progress report on research undertaken on the chemical budget of a lake, outlining the importance of nitrogen and phosphorus in governing the production of life in freshwater. The report uses the Rivers Brathay and Leven, which flow into Windermere, as examples. The report also refers to the Rivers Rothay, Troutbeck and Cunsey. A table is including which shows the monthly average nitrate content (mg per litre) of the River Brathey and River Leven for 1937 into 1938. The report also includes a figure showing Windermere lake levels, discharge and rainfall during 1937. It also briefly considers possible anthropogenic influences on water quality.

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An article reviewing the work undertaken looking at the seasonal variation of chemical conditions in water at various depths in lakes. The laboratory tests undertaken for the research is outlined, as well as details of the sampling locations and the staff involved with the work. One figure shows the seasonal variation in the amounts of dissolved substances in the surface water of Windermere during 1936. Another figure shows seasonal varation inthe dry weight of phyto- and zooplankton in Windermere. Seasonal changes are discussed further and a table is included showing chemical conditions in winter and summer for Windermere.

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The area studied was the River Frome system below Dorchester. The main river has its origins mainly in chalk springs, although some of its tributaries have surface run-off from farm lands and heath-lands. Thus the chemistry of the river is affected by changes in land practice and differences in the geology of the catchment area. Regular chemical analysis of chalk waters started at the River Laboratory in 1964, Regular weekly analyses have been carried out since 1965 at Bere Stream (a small chalk stream) and the River Frome (a large chalk stream); also single samples have been analysed to provide preliminary information. In 1970-71 an attempt was made to discover the contribution each main source made to the flow and chemical composition of the River Frome. Results of these investigations are presented in the paper.

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The chemical speciation of both metals and non-metals, the use of polarographic techniques, and application to the study of the chemistry of anoxic waters are considered. In the first part of the paper unfamiliar terminology is explained and then an example of simple lake chemistry is presented to illustrate why the concept of speciation is necessary.

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The overall goal of the joint research project is to relate the chemical reactions involved in the formation of organo-aluminium complexes under acid conditions to their toxic effects on the physiology of aquatic organisms. Finally, this research is intended to predict toxic effects arising from acidity and aluminium under varying environmental conditions. This interim report examines the chemical modelling of ion-binding by humic substances where a computer model has been developed and is being tested using field data, and conditions required for the precipitation of aluminium in surface waters.

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Analyses of pond water and mud samples show that nitrifying bacteria (including ammonifying bacteria, nitrite bacteria, nitrobacteria and denitrifying bacteria) are in general closely correlated with various physico-chemical factors, ammonifying bacteria are mainly correlated with dissolved oxygen; denitrifying bacteria are inversely correlated with phosphorus; nitrite bacteria are closely correlated with nitrites, nitrobacteria are inversely correlated with ammoniac nitrogen. The nitrifying bacteria are more closely correlated with heterotrophic bacteria. Nitrobacteria are inversely correlated with anaerobic heterotrophic bacteria. The correlation is quite weak between all the nitrite bacteria which indicates that the nitrite bacteria have a controlling and regulating function in water quality and there is no interdependence as each plays a role of its own. The paper also discusses how the superficial soil (pond mud down to 3.5 cm deep) and different layers of the mud affect the biomass of bacteria. The study shows that the top superficial layer (down to 1.5 cm deep) is the major area for decomposing and converting organic matter.

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This report is the second in a series from a project to assess land-based sources of pollution (LBSP) and effects in the St. Thomas East End Reserves (STEER) in St. Thomas, USVI, and is the result of a collaborative effort between NOAA’s National Centers for Coastal Ocean Science, the USVI Department of Planning and Natural Resources, the University of the Virgin Islands, and The Nature Conservancy. Passive water samplers (POCIS) were deployed in the STEER in February 2012. Developed by the US Geological Survey (USGS) as a tool to detect the presence of water soluble contaminants in the environment, POCIS samplers were deployed in the STEER at five locations. In addition to the February 2012 deployment, the results from an earlier POCIS deployment in May 2010 in Turpentine Gut, a perennial freshwater stream which drains to the STEER, are also reported. A total of 26 stormwater contaminants were detected at least once during the February 2012 deployment in the STEER. Detections were high enough to estimate ambient water concentrations for nine contaminants using USGS sampling rate values. From the May 2010 deployment in Turpentine Gut, 31 stormwater contaminants were detected, and ambient water concentrations could be estimated for 17 compounds. Ambient water concentrations were estimated for a number of contaminants including the detergent/surfactant metabolite 4-tert-octylphenol, phthalate ester plasticizers DEHP and DEP, bromoform, personal care products including menthol, indole, n,n-diethyltoluamide (DEET), along with the animal/plant sterol cholesterol, and the plant sterol beta-sitosterol. Only DEHP appeared to have exceeded a water quality guideline for the protection of aquatic organisms.