Freshwater eutrophication

Chlorophylls are produced by all photosynthetic organisms — and even by some nonphotosynthetic bacteria — and details of their structures depend on their source. Collectively they represent a considerable reserve of organic carbon and nitrogen, although little seems to have been established on their persistence. A wide range of transformation products of chlorophylls has been recovered from the sediments of a freshwater eutrophic lake, and these included the unusual sterol esters of pyrophaeophorbides (Eckardt et al. 1995). It is also presumable that such chlorophyll transformation products produce the pyrroles and indoles that have been described in sediment pyrolysates noted above. 

Midpoint indicatois Climate change. Ozone depletion. Photochemical oxidant formation. Particulate matter formation. Ionising radiation. Terrestrial acidification. Human toxicity. Terrestrial ecotoxicity. Freshwater ecotoxicity. Marine ecotoxicity. Metal depletion. Fossil depletion. Water depletion. Freshwater eutrophication. Marine eutrophication. Agricultural land occupation. Urban land occupation and Natural land transformation. Endpoint indicators Human health. Ecosystem diversity and Resource availability. 

Resource availability Ecosystem diversity Human health Natural land transformation Urban land occupation Agricultural land occupation Marine eutrophication Freshwater eutrophication Water depletion Fossil depletion Metal depletion Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Human toxicity Terrestrial acidification Ionising radiation Particulate matter formation Photochemical oxidant formation Ozone depletion Climate change L -10%... 

Climate change Ozone layer depletion Terrestrial acidification Human toxicity Terrestrial ecotoxicity Freshwater ecotoxicity Freshwater eutrophication Agricultural land occupation... 

To cover a wider spectrum of potential environmental impacts, several indicators from different impact assessment methods were employed, as implemented in Simapro v8.0.2 global warming potential over 100 years (GWPioo) (IPCC, 2006), renewable and nonrenewable cumulative energy demand (CED) [v 1.08] (Hischier et al., 2010), ecotoxicity [USEtox vl.03] (Rosenbaum et al., 2008), agricultural land occupation (ALO) and freshwater eutrophication (EE) [ReCIPe v.1.09] (Goedkoop et al., 2013). 

In this study the ReCiPe methodology (Goedkoop et al., 2008) [3] was adopted. The following midpoint impact categories are included climate change, ozone depletion, human toxicity, photochemical oxidant, particulate matter formation, ionizing radiation, acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity. 

H. Bernhardt, in Eutrophication Research and Application to Water Supply, ed. D. W. Sutcliffe and J. G. Jones, Freshwater Biologieal Assoeiation, Ambleside, 1992, p. 1. 

D. M. Harper, Eutrophication of Freshwaters, Chapman and Hall, London, 1992. 

Ocean prevents eutrophication. Much more water flows into the Mediterranean Sea than is required to replace evaporation from it. The excess, high salinity water exits Gibraltar below the water flowing in af fhe surface. Nufrients that enter the Mediterranean Sea from pollution sources are utilized by marine phytoplankton that sinks and exits with the outflow. Another example is that estuaries often have lower salinity or even freshwater at the surface with a denser saline layer at the bottom. An estuarine circulation occurs with nutrients being trapped in the saline bottom water. 

Rural Exodus Syndrome Environmental degradation through abandonment of traditional agricultural practices Loss of ecosystems and species diversity, genetic erosion, eutrophication, acid rain, greenhouse effect, contamination of water bodies and air, freshwater scarcity, soil degradation, marginalization, rural exodus... 

Cyanobacterial toxins (both marine and freshwater) are functionally and chemically a diverse group of secondary chemicals. They show structure and function similarities to higher plant and algal toxins. Of particular importance to this publication is the production of toxins which appear to be identical with saxitoxin and neosaxitoxin. Since these are the primary toxins involved in cases of paralytic shellfish poisons, these aphantoxins could be a source of PSP standards and the study of their production by Aphanizomenon can provide information on the biosynthesis of PSP s. The cyanobacteria toxins have not received extensive attention since they have fewer vectors by which they come in contact with humans. As freshwater supplies become more eutrophicated and as cyanobacteria are increasingly used as a source of single cell protein toxic cyanobacteria will have increased importance (39). The study of these cyanobacterial toxins can contribute to a better understanding of seafood poisons. 

Malley, D. F. Chang, P. S. S. Schindler, D. W. Decline of Zooplankton Populations following Eutrophication of Lake 227, Experimental Lakes Area, Ontario 1969-1974 Dept. Fisheries Oceans, Freshwater Institute, Winnipeg, Manitoba, 1977. 

Estimates of denitrification rates range from 54 to 345 xmol/m2 per hour in streams with high rates of organic matter deposition, 12 to 56 xmol/m2 per hour in nutrient-poor oligotrophic lakes, and 42 to 171 xmol/m2 per hour in eutrophic lakes (62). Rudd et al. (64) reported an increase in the rate of denitrification from less than 0.1 to over 20 xmol/m2 per hour in an oligotrophic lake when nitric acid was added in a whole-lake experimental acidification. This result suggests that freshwater denitrification may be limited by N03" availability. In deep muds of slow-flowing streams, the process can effectively reduce N03" concentrations in... 

The potential for N deposition to contribute to the eutrophication of freshwater lakes is probably quite limited. Eutrophication by atmospheric inputs of N is a concern only in lakes that are chronically N-limited. This condition occurs in some lakes that receive substantial inputs of anthropogenic P and in many lakes where both P and N are found in low concentrations (e.g., Table III). In the former case the primary dysfunction of the lakes is an excess supply of P, and controlling N deposition would be an ineffective method of water-quality improvement. In the latter case the potential for eutrophication by N addition (e.g., from deposition) is limited by low P concentrations additions of N to these systems would soon lead to N-sufficient, and phosphorus-deficient, conditions. The results of the NSWS shown in Table III, for example, can be used to calculate the increase in N concentration that would be required to push N-limited lakes into P limitation (assuming total P concentrations do not change). An increase of only... 

Cyanobacterial (Blue-Green Bacteria) Toxins. Cyanobacterial poisonings were first recognized in the late 1800s. Human poisonings are rare however, kills of livestock, other mammals, birds, fish, and aquatic invertebrates are common. It is caused by a variety of biotoxins and cytotoxins, including anatoxin, microcystin, and nodularin produced by several species of cyanobacteria, including Anabaena, Aphanizomenon, Nodularia, Oscillatoria, and Microcystis. The main contamination problems include all eutrophic freshwater rivers, lakes, and streams. 

Here we present one example to illustrate the utility of 15N for providing information about the source of dissolved organic nitrogen in a freshwater ecosystem. The 15N contents of fulvic acid fractions of different size varied slightly and were similar to the value for the 15N content of the synfulvic acid fraction in a eutrophic coastal pond in Antarctica (Table I) (Brown et al., 2002). Continuous production of mucilage by the chlorophyte population in the pond and diffusion of DOM from the sediments are the two main DOM sources these data suggest that the same source predominates for all of these fulvic acid fractions. 

Sinsabaugh, R. L., and C. M. Foreman. 2001. Activity profiles of bacterioplankton in a eutrophic river. Freshwater Biology 46 1-12. 

Eutrophication reduces the 02 content and increases the presence of NH4 in freshwater. These changes can affect the processes of transformation of carbon and nitrogen giving CH4 and N20, which are emitted to the atmosphere. Liikanen and Martikainen (2003) studied these processes in Finland and showed that in the case of a eutrophicated lake the bottom sediment can emit up to 7.9 mmol m-2 da-1 of CH4 and 7.6 pmol m 2 da 1 of N20, with oxygen being a key factor in the regulation of these fluxes through N03 formation. 

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