Aquatic organism

Toxicity to aquatic organisms is also low [43], data on fish, barnacle nauplii and unicellular algae are presented in Table 9. 

As a herbicide, acrolein is most effective in conholling dense accumulations of submerged weeds in habitats where water flow is rapid and uniform, such as irrigation canals and rapidly flowing streams. Acrolein is lethal to various genera of 

In addition to weeds, acrolein is used to control fouling organisms in cooling water systems. Effective control was established in a once-through cooling system of a steel mill with continuous application of 200.0 p,g 

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Figure 10.1-6. Simplified model of a higher aquatic organism and of the toxicokinetic processes taking place.

In a battery of tests, which determine the tendency of chemicals to inhibit aquatic organisms, accumulate in such organisms, and degrade in the environment, 2-hydroxy-2-nitro-l,3-propanediol was found to have low potential for harm in the environment (7). 

Eield tests for aquatic organisms, simulated, actual... 

Pesticide Assessment Guidelines, Data Requirements Subdivision D, Product Chemistry E, Ha ard Evaluation—Wildlife and Aquatic Organisms F, Ha ard Evaluation—Human and Domestic Animals G, Product Peformance H, Eabeling , Experimental Use Permits J, Ha ard Evaluation—Nontafget Plants K,... 

The majority of studies on the acute and chronic toxicity of phthalates to aquatic organisms show no toxic effects at concentrations 200—1000 times the water solubiUty. However, there are some studies iadicatiag higher toxicity which are beheved to be due to the flotation and entrapment effects outlined above. 

Thermal effects on aquatic organisms have been given critical scientific review. Annual reviews of the thermal effects Hterature have been pubUshed beginning in 1968 (12). Water temperature criteria for protection of aquatic life were prepared by the NAS in 1972, and these criteria have formed the basis of the EPA recommendations for estabUshing water temperature standards for specific water bodies (13,14). 

Fig. 7. Toxicity of chlorine to aquatic organisms, (a) Time-dependent mortaUty (50%) of four example species in various levels of total residual chlorine in the laboratory, where for A, A.losa aestivalis and B, Salmogairdnerii r (correlation coefficient of the curve) = —0.96 and for C, P/euroneetesplatessa and D, Salmo trutta r = —0.98. (b) A summary of chlorine toxicity to freshwater species, indicating overall no-effect thresholds for acute and chronic exposures. Numbers indicate where more than one test yielded the same result. A different summary figure appHes to marine organisms because of differences in the...

Aquatic organisms, such as fish and invertebrates, can excrete compounds via passive diffusion across membranes into the surrounding medium and so have a much reduced need for specialised pathways for steroid excretion. It may be that this lack of selective pressure, together with prey-predator co-evolution, has resulted in restricted biotransformation ability within these animals and their associated predators. The resultant limitations in metabolic and excretory competence makes it more likely that they will bioacciimiilate EDs, and hence they may be at greater risk of adverse effects following exposure to such chemicals. 

The LC50 is the lethal concentration of chemical (e.g. in air or water) that will cause the death of 50% of the sample population. This is most appropriate as an indicator of the acute toxicity of chemicals in air breathed (or in water, for aquatic organisms). Table 5.11 illustrates the use of LD50 values to rank the toxicity of substances. 

Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment... 

Seine net A net designed to collect aquatic organisms inhabiting natural waters from the shoreline to 3 depths is called a seine net. Most often a plankton seine. Selvage A loom finished edge that prevents cloth unravelling. 

Lindstrom and Schubert63 applied GC-MS, GC-MS-MS and direct inlet MS-MS to determine 1,1-dichlorodimethyl sulfone (201, DDS) in aquatic organisms outside a pulp mill bleach plant. Both GC-MS-MS and direct inlet MS-MS of tissue extracts of fish and mussel appeared to be sensitive, selective and fast techniques for the determination of DDS. 

Almost all aquatic organisms rely on the presence of dissolved oxygen for respiration. Although oxygen is nonpolar, it is very slightly soluble in water and the extent to which it dissolves depends on its pressure. We have already seen (in Section 4.2) that the pressure of a gas arises from the impacts of its molecules. When a gas is introduced into the same container as a liquid, the gas molecules can burrow into the liquid like meteorites plunging into the ocean. Because the number of impacts increases as the pressure of a gas increases, we should expect the solubility of the gas—its molar concentration when the dissolved gas is in dynamic equilibrium with the free gas—to increase as its pressure increases. If the gas above the liquid is a mixture (like air), then the solubility of each component depends on that component s partial pressure (Fig. 8.21). 

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