The impact of nitrogen contamination and river modification on a Mississippi River floodplain lake.

摘要: Abstract Anthropogenic nitrogen contamination has increased in ecosystems around the world (frequently termed “nitrogen cascade”). Coke production for steel manufacturing is often overlooked as a source of to natural ecosystems. We examined sediment cores from Horseshoe Lake, floodplain lake located just East St. Louis Missouri (USA) test whether coking plant effluent could be traced using stable isotopes and diatom microfossils. The distribution δ15N values surface samples shows highest near effluent. Stable 4 mixing model showed three sources since 1688 CE. first (active between 1920 CE) had calculated value ranging − 0.4 1.1‰ depending on core. After second with 10.6 15.4‰ became active. change these coincides construction shore. A third approximately 7.0‰ was present at all times represents background. microfossil assemblages CE late 1800s are dominated by planktonic species Aulacoseira granulata periphytic benthic genera Gomphonema, Cocconeis, Lyrella. Staurosira indicating shift high flow riverine environments epipelic environment. Diatom microfossils seem track reduction flooding due leveeing isolation river. Our results show how can used inputs industrial sources. changes corresponded connectivity Mississippi River its floodplain.