A Chlorine-36 and Carbon-14 Study of the Role of Chlorine in the Forest Ecosystem

0079023 - ÚEB 2007 RIV GB eng J - Journal Article
Matucha, Miroslav - Gryndler, Milan - Forczek, Sándor - Schröder, P. - Bastviken, D. - Rohlenová, Jana - Uhlířová, H. - Fuksová, Květoslava
A Chlorine-36 and Carbon-14 Study of the Role of Chlorine in the Forest Ecosystem.
[Studie role chloru v lesním ekosystému za užití chloru 36 a uhlíku 14.]
Journal of Labelled Compounds and Radiopharmaceuticals. Roč. 50, č. 1 (2007), s. 1-3. ISSN 0362-4803. E-ISSN 1099-1344
R&D Projects: GA ČR GA522/02/0874; GA ČR GA526/05/0636
Institutional research plan: CEZ:AV0Z50380511
Keywords : [14C]-synthesis * labeled compounds * tetrahydrocyclopenta[b]indol-3-yl acetic acid
Subject RIV: EF - Botanics
Impact factor: 1.142, year: 2007

Radioisotopes carbon 14 and chlorine 36 were used to elucidate the environmental role of trichloroacetic acid (TCA) formerly taken to be a herbicide and a secondary air pollutant with phytotoxic effects. However, use of 14C-labeling posed again known analytical problems, especially in TCA extraction from the sample matrix. Therefore--after evaluation of available methods--a new procedure using decarboxylation of [1,2-14C]TCA combined with extraction of the resultant 14C-chloroform with a non-polar solvent and its subsequent radiometric measurement was developed. The method solves previous difficulties and permits an easy determination of amounts between 0.4 and 20 kBq (10 - 500 ng g(-1)) of carrier-less [1,2-14C]TCA in samples from environmental investigations. The procedure is, however, not suitable for direct [36Cl]TCA determination in chlorination studies with 36Cl. Because TCA might be microbially degraded in soil during extraction and sample storage and its extraction from soil or needles is never complete, the decarboxylation method--i.e. 2 h TCA decomposition to chloroform and CO2 in aqueous solution or suspension in closed vial at 90 degrees C and pH 4.6 with subsequent CHCl3 extraction-is recommended here, estimated V < 7%. Moreover, the influence of pH and temperature on the decarboxylation of TCA in aqueous solution was studied in a broad range and its environmental relevance is shown in the case of TCA decarboxylation in spruce needles which takes place also at ambient temperatures and might amount more than 10-20% after a growing season. A study of TCA distribution in spruce needles after below-ground uptake shows the highest uptake rate into current needles which have, however, a lower TCA content than older needle-year classes, TCA biodegradation in forest soil leads predominatingly to CO2.

V článku je přehledně ukázána role chloru v lesním ekosystému. Chlorid není inertní, ale reaguje především za účasti mikroorganismů s půdní organickou hmotou za vzniku chlorovaných látek, kupř. chloroctových kyselin (CAA). Je presentován jejich vznik v lesní půdě spolu s jejich mikrobiální degradací, CAA tedy představují degradační půdní intermediáty. V lesní půdě dochází rovněž k chloraci fulvokyselin a dalších huminových látek i jejich dehalogenaci.
Permanent Link: http://hdl.handle.net/11104/0143924