As urbanization progresses around lakes and ponds and industrial activities and development works become more prevalent, the pollution of lakes and ponds is worsening. The most typical example of this is lake pollution caused by eutrophication. When large amounts of urban sewage, industrial wastewater, agricultural and livestock wastewater, etc., which contain nitrogen and phosphorus, which are nutrients for phytoplankton, flow into a lake, the occurrence of phytoplankton increases rapidly. As a result, transparency decreases significantly and light cannot reach the depths, causing a decrease in submerged plants such as charophyte, eelgrass, and hydrilla, and instead, floating-leaf plants such as water chestnut, water chestnut, and floating heartfish flourish. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
湖沼の周辺で都市化が進み,産業活動や開発工事が盛んになるにつれ,湖沼の汚濁が進んでいる。その中で最も代表的な例が富栄養化による湖沼の汚濁である。植物プランクトンの栄養源となる窒素やリンを含む都市下水,工業廃水,農業・畜産業排水などが湖に大量に流入すると植物プランクトンの発生が急激に増加する。その結果,透明度は著しく低下するので,深いところまで光が届かなくなり,このため,シャジクモ,エビモ,クロモなどの沈水植物は減少し,代わりにヒシ,ガガブタ,アサザなどの浮葉植物が繁茂する。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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