Organic Contaminants in Aquatic Macrophytes.

MENONE. ML Y MORENO, VJ.

Wissenschaftliche Zusammenarbeit mit Argentinien: Begrenzung und Zuversicht. Arbeits- und Diskussionspapier 5/2006. Fundación Alexander von Humboldt- Alemania.

Año: 2005 p. 71 - 78

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are some of the more ubiquitous and toxic organic pollutants worldwide. The first group has been used in agriculture and health and the second ones in the industry, mainly in electrical transformers and as fireproofing agents in paints and plastics. Given these uses, the principal sources of PCBs encountered in the environment include open burning or incomplete combustion of PCB-containing solid waste, vaporization in open applications, accidental spills from transformers and disposal into sewage sludge systems (Connell, 1997). Why are we interested in plants? Emergent, submergent, and floating leaved macrophytes, algae, periphyton, and phytoplankton form the base of most aquatic food chains. They are important in nutrient cycling and respond rapidly to water quality changes. *They act as an important global sink for environmental chemicals*The plant biomass can act as a vehicle for soil persistence of xenobiotics * They play an important role in the persistence and bioaccumulation of lipophilic xenobiotics in food chains. The "Green Liver" concept. Plants may function as the "green livers" since it was discovered that they exhibit nearly the same set of detoxication enzymes which can be found in animal liver (Sandermann et al., 1977). The exposure of plants to stressors, either natural or those introduced by man, usually induces specific biochemical responses in plants. Many examples of plant metabolic sequences of transformation mostly done by cytochrome P-450 monooxygenases (phase I), conjugation mostly done by glutatione S- transferases and glucosyltransferases (phase II) and internal compartmentation reactions mostly in cell wall fractions or in the vacuole (phase Ill) have been summarized (Sandermann, 1994). What are the approaches we use to study contaminants? (A) Biomonitoring of organic contaminants: The use of indicator organisms (biomonitors) in situ to identify and quantify toxicants in an environment. (B) 8iomarkers of organic contaminants (e.g. detoxication and oxidative stress enzymes) (C) Use of biomarkers for biomonitoring As an example of the study of biomarkers (B) I present part of the results obtained during my fellowship period in Germany, at the Leibniz Institute of Freshwater Ecology and Inland Fisheries, AG Biogeochemical Regulation, Muggelseedamm 301, Berlin 12587. The main objectives of the study were to investigate the effects of 3-chlorobiphenyl in the C. demersum and to assess the capacity of detoxication systems in this macrophyte. The particular aims were a) to establish dose- response curves after short time heavy exposure of 3-chlorobiphenyl, b) to measure effects on photosynthetic oxygen production and total glutathione content, c) to determine glutathione Stransferases and glutathione reductase activities. C. demersum showed different sensitivity or different routes of detoxication to compounds like 3- chlorobiphenyl and the insecticide cypermethrin.