Aquatic gill

It should be noted that the BCF can also be determined solely from the uptake curve of the chemical in the organisms. The method and equations for calculating the BCF values in this way were recently published by Wang et al. [23]. An important paper on different compartment models and the mathematical descriptions of uptake, elimination and bioconcentration of xenobiotics in fish and other aquatic gill-breathing organisms was given by Butte [24]. 

Equation (16) can be used to predict the half-life of organic chemicals in fish and other aquatic gill-breathing organisms if the chemical does not form bound residues. In case that the organic chemical is metabolized only to a minimal extent or not at all the bioconcentration factor on a lipid basis (BCFl) is equal to the n-octanol/water partition coefficient (Kqw) (see Sect. 7) so that Eq. (16) gives... 

It was found that adverse effects, disease and mortality in both treated and control fish can influence the kinetics of the chemical in fish. Mortality, therefore, should normally be <10% at the end of the test. Geyer et al. [29] found that the elimination rate of a chemical in aquatic gill-breathing animals is greater, if toxic effects occur and especially if the lipid content is decreasing during the test. That means that the half-life (ti/2) and the bioconcentration factor of a chemical is smaller if the concentration in the water is so high that toxic effects occur. Therefore, the concentration of the test chemical in the water has to be so low that... 

The major routes of uptake of xenobiotics by animals and plants are discussed in Chapter 4, Section 4.1. With animals, there is an important distinction between terrestrial species, on the one hand, and aquatic invertebrates and fish on the other. The latter readily absorb many xenobiotics directly from ambient water or sediment across permeable respiratory surfaces (e.g., gills). Some amphibia (e.g., frogs) readily absorb such compounds across permeable skin. By contrast, many aquatic vertebrates, such as whales and seabirds, absorb little by this route. In lung-breathing organisms, direct absorption from water across exposed respiratory membranes is not an important route of uptake. 

Nonpolar gases are only slightly soluble in water. For example, water in contact with the Earth s atmosphere contains O2 at a concentration of only about 2.5 x 10 M and CO2 at about 1 x 10 M. Nevertheless, these small concentrations are essential for aquatic life. Fish and other aquatic animals use their gills to extract O2 dissolved in water, and unless that oxygen is replenished, these species die. Submerged green plants carry out photosynthesis using dissolved carbon dioxide, which also must be replenished for these plants to survive. 

Absorption across biological membranes is often necessary for a chemical to manifest toxicity. In many cases several membranes need to be crossed and the structure of both the chemical and the membrane need to be evaluated in the process. The major routes of absorption are ingestion, inhalation, dermal and, in the case of exposures in aquatic systems, gills. Factors that influence absorption have been reviewed recently. Methods to assess absorption include in vivo, in vitro, various cellular cultures as well as modelling approaches. Solubility and permeability are barriers to absorption and guidelines have been developed to estimate the likelihood of candidate molecules being absorbed after oral administration. ... 

Bainy ACD, Saito E, Carvalho PSM, Junqueira VBC (1996) Oxidative stress in gill, erythrocytes, liver and kidney of Nile tilapia (Oreochromis niloticus) from a polluted site. Aquat Toxicol 34 151-162... 

Van der Putte, I. and P. Part. 1982. Oxygen and chromium transfer in perfused gills of rainbow trout Salmo gairdneri) exposed to hexavalent chromium at two different pH levels. Aquat. Toxicol. 2 31-45. 

Playle, R.C., D.G. Dixon, and K. Bumison. 1993a. Copper and cadmium binding to fish gills modification by dissolved organic carbon and synthetic ligands. Canad. Jour. Fish. Aquat. Sci. 50 2667-2677. 

Crespo, S., R. Flos, J. Balasch, and G. Alonso. 1979. Zinc in the gills of dogfish (Scyliorhinus canicula L.) related to experimental aquatic zinc pollution. Comp. Biochem. Physiol. 63C 261-266. 

Gill, K. A. and P.J. Walsh. 1990. Effects of temperature on metabolism of benzo[a]pyrene by toadfish (Opsanus tau) hepatocytes. Canad. Jour. Fish. Aquat. Sci. 47 831-837. 

McCloskey, J.T. and T.T. Oris. 1993. Effect of anthracene and solar ultraviolet radiation exposure on gill ATPase and selected hematologic measurements in the bluegill sunfish (Lepomis macrochirus). Aquat. Toxicol. 24 207-218. 

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