The Sitemap XML protocol is also extended to provide a way of listing multiple Sitemaps in a 'Sitemap index' file. The maximum Sitemap size of 50 MiB or 50,000 URLs means this is necessary for large sites. An example of Sitemap index referencing one separate sitemap follows.
Cultural or artificial eutrophication occurs when human activity introduces increased amounts of these nutrients, which speed up plant growth and eventually choke the lake of all of its animal life.n nature, eutrophication is a common phenomenon in freshwater ecosystems and is really a part of the normal aging process of many lakes and ponds. Some never experience it because of a lack of warmth and light, but many do.
The main causes of eutrophication are. 1  natural run-off of nutrients from the soil and the weathering of rocks. 2  run-off of inorganic fertiliser (containing nitrates and phosphates). 3  run-off of manure from farms (containing nitrates, phosphates and ammonia).