Occurrence in environment

Helmig D, J Arey, WP Harger, R Atkinson, J Lopez-Cancio (1992a) Formation of mutagenic nitrodibenzopy-ranones and their occurrence in ambient air. Environ Sci Technol 26 622-624. 

Prediction of chemical occurrence is a difficult task that depends on multitude of factors (i.e., physical-chemical properties, climate conditions, amount of product, mode of application, and exchange processes), but these models in combination with laboratory analysis can be a powerful tool for evaluating the chemical occurrence in the environment. 

As mentioned before, environmental exposure is the first key aspect to develop risk characterization from a defined scenario (see Fig. 1). Experimental analysis is the most obvious and classical procedure for determining the chemical occurrence in the environment. Measuring environmental concentrations (MECs) is more accurate and reflects the reality better than any other method, but the main drawback is the large amount of resources required for these laboratory measurements. Field environmental monitoring programs have become increasingly expensive as... 

Postigo C, Lopez de Alda MJ, Barcelo D (2010) Drugs of abuse and their metabolites in the Ebro river basin occurrence in sewage and surface water, sewage treatment plants removal efficiency, and collective drug usage estimation. Environ Int 36(l) 75-84... 

Chlordanes and their metabolites are ubiquitous in the environment at low concentrations, but at a high occurrence in samples analyzed. Atmospheric transport is considered to be the major route of global dissemination. Some chlordane isomers persist in soils for 3 to 15 years, although there seems to be little accumulation of chlordanes by crop plants grown in these soils. Lengthy persistence of various chlordane isomers, especially m-chlordane and trans-nonachlor, has been reported in certain organisms, but this has varied greatly between species and tissues. 

Levander, O.A. 1984. The importance of selenium in total parenteral nutrition. Bull. N. Y. Acad Med 60 144-155. Lo, M.T. and E. Sandi. 1980. Selenium occurrence in foods and its toxicological significance. A review. Jour. Environ. Pathol. Toxicol. 4 193-218. 

Very low levels are found in water and air. High levels in soils, sediments and animals. Occurrence in the environment related to chlorination degree obtained by photolysis >chlorination degree> persistence... 

Iron and its various oxidation state species are common components of the environment. In addition to the oxides FeO and Fe203, it is found in minerals such as hematite, goethite, and ferrihydrite, and in a number of hydroxy and oxy compounds. Because of its common occurrence in the environment in general, and in soil in particular, the total iron content of soil is usually not a useful piece of information. 

Andreozzi R, Caprio V, Ciniglia C et al (2004) Antibiotics in the environment occurrence in Italian STPs, fate, and preliminary assessment on algal toxicity of amoxicillin. Environ Sci Technol 38 6832-6838... 

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