D10: Impact of Contaminants - Hydromod

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Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants Atrazine FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Page 48 of 136 Atrazine is used as a nonselective herbicide [EXTOXNET]. Atrazine inhibits the photosynthesis in plants. The plants ingest the substance by the roots and the leaves [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. In 1987 the estimated world-wide production amounted 70 000 t [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. In 1990 more than 64 million acre of cropland were treated with atrazine in the USA [EXTOXNET]. Field of Application: In agriculture atrazine is used in agriculture for the weed control in corn and millet for more than 30 years [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. Primarily it is used in corn cultivation and the main input takes place between May and June. In Switzerland 60 t/a are used, in the catchment of the Mississippi 20 000 t and in the whole USA together 30 000 t [FENT 1998]. In Austria the increase of atrazine occurs with the enlargement of the corn cultivation. In former times, atrazine was used in amounts of 8 kg/ha. It was used in mixture with other herbicides for the weed control at rail facilities, industry and traffic areas. Here, the dosages mounted up to more than 20 kg/ha. This was a significant reason for the pollution of waters with atrazine and its metabolites [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. Elimination from the Sewage: Most of the communal sewage treatment plants does not eliminate atrazine out of the water. But by means of activated carbon filters they can be eliminated trouble-free [COMFORT and ROETH 1996]. Pollution Sources: Atrazine reaches the environment from agricultural areas (corn cultivation) during the application between May and June. Because of a great mobility atrazine reaches the ground water via infiltration and the surface waters via surface rainwash [FENT 1998]. A long distance transport of atrazine is possible by dust particles, fog and rain [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. In consequence of driftage or evaporation it attains the atmosphere and with the rainfall it reaches the waters and ground again [FENT 1998]. Environmental behaviour: In Austria's waters atrazine and its by-product desethylatrazine cause important residual problems. It was detected in the rain, ground water, surface water and the soil. The main problems of the atrazine usage are caused in the great prevalence in the environment and the persistence of atrazine an its metabolites in the ground water and the soil [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. In
Integrated Water Resource Management for Important Deep European Lakes and their Catchment Areas EUROLAKES D10: Impact of Contaminants FP5_Contract No.: EVK1-CT1999-00004 Version: 4.0 Date: 25/07/01 File: D10-vers.4.0.doc Page 49 of 136 the soil atrazine is predominantly metabolised microbial but also abiotically e. g. by sunlight and hydrolysis [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. The hydrolysis is fast in acidic or basic environments and rather slower in a neutral pH range. The average half-life period is 45 days. In soils with a low part of loam or low content of organic substances atrazine is moderate to highly volatile [EXTOXNET]. Under moist and warm conditions, the half-life period of atrazine in the topsoil is about 60 days. In subsurface soil or in water the half-life period is generally longer [COMFORT and ROETH 1996]. Under dry or cold conditions atrazine can persist more than a year. Because it does not adsorb strongly at soil particles atrazine has a high potential to contaminate the ground water despite its moderate water solubility [EXTOXNET]. The biodegradation in water and ground water is slower because here atrazine and its metabolites are very persistent [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. By the feeders the herbicide attains the epilimnion where it is subject to the different processes of water mixing. Between April and November (stratified lake) atrazine is spread in the epilimnion within some days. A continuos elimination takes place by the lake outflow. The vertical water mixing is significantly slower and transports a small amount into the metalimnion and the hypolimnion. During the winter circulation between December and March the residual amount of atrazine is spread in the whole lake [FENT 1998]. He also points out, that some by-products have also a small herbicide effect. Due to the low vapour pressure and a small henry-constant the volatility into the atmosphere is negligible. The relatively high water solubility of atrazine and the small distribution coefficient causing a relative high mobility from the soil into surface and ground water. Therefore atrazine sorbs hardly at sediment and soil particles. The microbial degradability is low. Atrazine is relatively persistent but there is no important bio-accumulation in organisms. Because the photochemical and biological degradation is also low, the disposition of atrazine in the lake is caused by the disposition and transport processes. Concentration in the Environment: During the application period highest values are measured. In the 1980's atrazine was measured in concentrations of more than 0.1 µg/l in many drinking water reservoirs. In the period of three weeks 0.5 - 9.1 µg/l and maximum values of 23 µg/l are measured in American rivers. Here the medium atrazine concentrations lie between 0.3 - 4.7 µg/l. In small lakes the values are specifically high. Surface runoff from agricultural fields continue approximately one month after the use and have values up to 250 µg/l. In May/June up to 0.15 µg/l are measured in the rain in Switzerland [FENT 1998]. Ecotoxicological Effects: For birds, beneficial animals (e. g. bees) and soil-dwelling organisms atrazine is extensively harmless. Atrazine does not accumulate itself in the food chain. The acute toxicity of atrazine for humans is low. Sporadically irritations of skin, eyes and the respiratory tract are recognised. Human toxicologically it is almost harmless. It is not safe to say that atrazine has a mutagenic res. teratogenic effect. In long-term studies an increased rate of breast cancer has been recognised. The EPA classified atrazine to be a "Possible Human Carcinogen". It is suspected to have an unwanted estrogene effect [FEDERAL ENVIRONMENT AGENCY, AUSTRIA]. Atrazine represses the photosynthesis and is an environmental chemical with a herbicide effect. In the water it mainly impairs algae and water plants but between related groups of organisms high species differences occur [FENT 1998]. For fishes atrazine is
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D10: Impact of Contaminants - Hydromod

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