Preconcentration and determination of trace elements in fresh water and sea water

1978 ◽  
Vol 291 (4) ◽  
pp. 273-277 ◽  
Author(s):  
P. Burba ◽  
K. H. Lieser ◽  
V. Neitzert ◽  
H. -M. Röber
Keyword(s):  
Trace Elements ◽  
Fresh Water ◽  
Sea Water

Comparison of the performance of FI-ICP-MS and FI-ETV-ICP-MS systems for the determination of trace elements in sea water

2001 ◽  
Vol 438 (1-2) ◽  
pp. 215-225 ◽  
Author(s):  
Dirce Pozebon ◽  
Valderi Luiz Dressler ◽  
Adilson José Curtius
Keyword(s):  
Trace Elements ◽  
Sea Water ◽  
Icp Ms

Preparation of U(VI) and Th(IV) alpha-sources from sea and fresh water samples by combining coprecipitation, solvent extraction and electrodeposition procedures

2004 ◽  
Vol 92 (3) ◽  
Author(s):  
R. Zarki ◽  
A. Elyahyaoui ◽  
A. Chiadli
Keyword(s):  
Solvent Extraction ◽  
Fresh Water ◽  
Water Samples ◽  
Sea Water ◽  
Accurate Determination ◽  
Simple Method ◽  
Considerable Saving ◽  
Initial Aqueous Solution ◽  
Initial Ph

SummaryA simple method combining coprecipitation, solvent extraction and electrodeposition for determining uranium and thorium in sea water and fresh water samples is developed. It offers a considerable saving in time, minimising chemical treatment and costs. The analytical procedure consists of enrichment of U and Th by coprecipitation with iron(III) hydroxides and subsequent extraction by diethylether solution and electrodeposition of each actinide in the extracting organic phase in which it was separated.The dependence of the coprecipitation, the extraction-electrodeposition and the overall yields of the above mentioned elements is examined in relation to the initial aqueous solution acidity and various amounts of iron carrier. At an initial pH between 6 and 10, quantitative coprecipitation of U and Th requires use of an Fe(III) quantity which depends on the acidity of these solutions. This quantity varies, under explored conditions, between 10 and 110mg/L. At a starting pH of 11, this coprecipitation becomes almost independent of Fe(III) amounts.The proposed procedure was used to analyse the content of U and Th isotopes in water samples. Recoveries of 60%-93% are obtained for uranium and 63%-86% for thorium. Good resolutions (37-56.5keV) are also achieved under optimum conditions. These resolutions allow to make accurate determination of U and Th isotopes in various water samples.

Osmotic Regulation in Mosquito Larvae

1950 ◽  
Vol 27 (2) ◽  
pp. 145-157 ◽  
Author(s):  
J. A. RAMSAY
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
External Medium ◽  
Freezing Point ◽  
Anterior Part ◽  
Osmotic Regulation ◽  
Opposite Process ◽  
Normal Environment ◽  
Different Parts

1. The processes of osmotic regulation in the larvae of Aedes aegypti and of A. detritus have been studied by determination of the freezing-point of samples of fluid collected from different parts of the gut. 2. In A. aegypti, kept in fresh water (its normal environment), the fluid passing down the intestine to the rectum is isotonic with the haemolymph. In the rectum it becomes strongly hypotonic before being eliminated. 3. In A. detritus, kept in sea water (its normal environment), the opposite process is observed, the fluid in the rectum becoming hypertonic to the haemolymph and approximately isotonic with the external medium before being eliminated. 4. In A. detritus, which is able to live in dilute media as well as in sea water, the only two specimens from fresh water available for examination were found to have the rectal fluid hypotonic to the haemolymph. 5. The ability of A. detritus, not possessed by A. aegypti, to produce an hypertonic fluid in the rectum is tentatively associated with a region in the anterior part of the rectum and lined with an epithelium distinctly different from that in the remainder of the rectum. This anterior region has not been found in A. aegypti.

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