Aquatic systems compounds

Under equiUbrium or near-equiUbrium conditions, the distribution of volatile species between gas and water phases can be described in terms of Henry s law. The rate of transfer of a compound across the water-gas phase boundary can be characterized by a mass-transfer coefficient and the activity gradient at the air—water interface. In addition, these substance-specific coefficients depend on the turbulence, interfacial area, and other conditions of the aquatic systems. They may be related to the exchange constant of oxygen as a reference substance for a system-independent parameter reaeration coefficients are often known for individual rivers and lakes. 

Solubihties of 1,3-butadiene and many other organic compounds in water have been extensively studied to gauge the impact of discharge of these materials into aquatic systems. Estimates have been advanced by using the UNIFAC derived method (19,20). Similarly, a mathematical model has been developed to calculate the vapor—Hquid equiUbrium (VLE) for 1,3-butadiene in the presence of steam (21). 

Rate constants for a large number of atmospheric reactions have been tabulated by Baulch et al. (1982, 1984) and Atkinson and Lloyd (1984). Reactions for the atmosphere as a whole and for cases involving aquatic systems, soils, and surface systems are often parameterized by the methods of Chapter 4. That is, the rate is taken to be a linear function or a power of some limiting reactant - often the compound of interest. As an example, the global uptake of CO2 by photosynthesis is often represented in the empirical form d[C02]/df = —fc[C02] ". Rates of reactions on solid surfaces tend to be much more complicated than gas phase reactions, but have been examined in selected cases for solids suspended in air, water, or in sediments. 

Loss of nitrogen compounds from soils is also a major pathway into the atmosphere for some compounds (e.g., N2O, NO, and NH3). As in the aquatic systems, parameters that play an important role in this process include the nature of the compound soil temperature, water content, pH, aeration of the soil and a concentration gradient of the gas in question. 

Fewer controlled experiments have been carried out for purely aquatic systems. Montmorillonite complexes with benzylamine at concentrations below 200 pg/L decreased the extent of mineralization in lake-water samples, although a similar effect was not noted with benzoate (Snbba-Rao and Alexander 1982). Even in apparently simple systems, general conclusions cannot therefore be drawn even for two structurally similar aromatic compounds, both of which are readily degradable nnder normal circumstances in the dissolved state. 

The identification of an allelopathic compound(s) and its mode of action may eventually permit the economical use of spikerush as a biological control measure in aquatic systems too fragile for chemical control, e.g. recreational water, drinking water, and certain irrigation canals. 

Diisopropyl methylphosphonate does not undergo direct or indirect photolysis in aquatic systems, as demonstrated by the stability of the compound in distilled water or in a natural water sample after 232 hours of reaction time with the mercury lamp filtered to exclude all wavelengths below 290 nm (Spanggord et al. 1979). 

Tin concentrations in water, air, soils, sediments, and other nonbiological materials are documented, but information is scarce except for aquatic systems (Maguire 1991 Table 8.6). In aquatic systems, several trends were evident. First, tin and organotin compounds tend to concentrate in... 

Papadopouluo-Mourkidou E. et al., 2001. Use of an automated online SPE-HPLC method to monitor caffeine and selected aniline and phenol compounds in aquatic systems of Macedonia-Thrace, Greece. Frese-nius J Anal Chem 371 491. 

Baughman, G.L., and T.A.Perenich. 1988. Fate of dyes in aquatic systems I. Solubility and partitioning of some hydrophobia dyes and related compounds. Environ. Toxicol. Chem. 7 183-200. 

No experimental information could be found in the available literature on bioconcentration or bioaccumulation of endrin aldehyde or endrin ketone. Estimated BCFs indicate some potential for bioaccumulation for both compounds. No information was found on concentrations of either of these compounds in aquatic systems, but it would be expected that levels would be nondetectable or very low, and that they would continue to decline. Therefore, additional information is not needed at this time. 

Several factors govern the transport and fate of hydrophobic organic chemicals in sediment/water environments microbially mediated reactions and sorption are major processes affecting the fate of these compounds in aquatic systems [166,366-368]. Aryl halides have been shown to undergo microbially-mediated dehalogenation under anaerobic conditions [38, 52, 68, 105, 116,... 

Soil Metabolites of endosulfan identified in seven soils were endosulfan diol, endosulfanhydroxy ether, endosulfan lactone, and endosulfan sulfate (Dreher and Podratzki, 1988 Martens, 1977). Endosulfan sulfate was the major biodegradation product in soils under aerobic, anaerobic, and flooded conditions. In flooded soils, endolactone was detected only once, whereas endodiol and endohydroxy ether were identified in all soils under these conditions. Under anaerobic conditions, endodiol formed in low amounts in two soils (Martens, 1977). These compounds, including endosulfan ether, were also reported as metabolites identified in aquatic systems (Day, 1991). Endosulfan sulfate was the major biodegradation product in soils under aerobic, anaerobic, and flooded conditions (Martens, 1977). In flooded soils, endolactone was detected only once whereas endodiol and endohydroxy ether were identified in all soils under these conditions. Under anaerobic conditions, endodiol formed in low amounts in two soils (Martens, 1977). 

Hustert, K., Mansour, M., Parlar, H., and Korte, F. The EPA test - A method to determine the photochemical degradation of organic compounds in aquatic systems, Chemosphere, 10(9) 995-998, 1981. 

Simmons, M.S. and Zepp, R.G. Influence of humic substances on photolysis of nitroaromatic compounds in aquatic systems. Water Res., 20(7) 899-904, 1986. 

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