Eutrophication Subject

Note that the maintenance of water quaUty and hence stream standards are not static, but subject to change with the municipal and industrial environment. For example, as the carbonaceous organic load is removed by treatment, the detrimental effect of nitrification in the receiving water increases. Eutrophication may also become a serious problem in some cases. These considerations require an upgrading of the required degree of treatment. 

The introduction of surfactant products into the environment, after use by consumers or as part of waste disposed during manufacture, is regulated by the Clean Water Act, the Clean Air Act, and the Resource Conservation and Recovery Act. In this respect, surfactants are subject to the same regulations as chemicals in general. There are, however, two areas of specific relevance to surfactants and detergent products, ie, biodegradabiUty and eutrophication. 

Dobolyi and Bidlo [76] determined the phosphorus-containing minerals in Balatien lake sediment, and thus the forms in which the phosphorus responsible for the accelerating eutrophication of the lake are present. Samples were subjected to chemical, electron microscope and X-ray analysis. Hydroxylapatite was identified, but no proof of the presence of other phosphorus minerals was obtained. 

Table 11.5 shows that sedimentation rates of 0.1 - 2 g nr2 d 1 are typically observed in lakes still higher values are found in very eutrophic lakes. The settling material can be collected in sediment traps it can then be characterized in terms of chemical composition, morphology, and size distribution of the particles. The composition is subject to seasonal variations caused primarily by different biological activities in the various seasons. Representative examples for Lakes Zurich and Constance are given in Fig. 11.10. These two lakes are prealpine lakes, located in regions of predominantly calcareous rocks, both are under the influence of eutrophication. 

The effects of N supply on uptake and growth rates in phytoplankton and periphyton are the subject of volumes of literature, a summary of which is beyond the scope of this chapter. However, certain aspects of the limitation of algal growth by the supply of N and other nutrients will be discussed later in the section on eutrophication by N deposition. Other details on algal nutrition can be found in reviews by Goldman and Glibert (31), Button (32), Kilham and Hecky (33), and Hecky and Kilham (34). 

The importance of redox effects on coupled iron-phosphorus cycling in freshwater systems has been the subject of study in applied environmental science, where phosphate removal from eutrophic natural waters and wastewaters, by sorption onto Fe-oxyhydroxide phases, has been explored as a remediation measure. Phosphate also has a pronounced tendency to sorb onto Al-oxyhydroxides, and these phases have been used in remediation of phosphate overenriched aquatic systems, as well (e.g., Leckie and Stumm, 1970). 

The entire biosphere is today subjected to the consequences of human activities and to their combined impacts on the enviromnent and biodiversity. These impacts often translate into modifications of the chemical properties of the enviromnent which are notably observed in the most remote areas of the globe (contamination by organic pollutants persisting in polar regions, acidification and anoxia of deep water of certain oceanic regions, eutrophication and/or soil erosion). Despite this, the concepts and tools to imderstand the impacts of these multiple abiotic constraints at different spatio-temporal scales, on diversified communities and in interactions are missing. 

---