Responses of coastal sediment phosphorus release to elevated urea loading

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Ma S., Dong X., Jeppesen E., Sondergaard M., Cao J., Li Y., ...More

MARINE POLLUTION BULLETIN, vol.174, 2022 (SCI-Expanded)

• Publication Type: Article / Article
• Volume: 174
• Publication Date: 2022
• Doi Number: 10.1016/j.marpolbul.2021.113203
• Journal Name: MARINE POLLUTION BULLETIN
• Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, PASCAL, Aerospace Database, Agricultural & Environmental Science Database, Aquatic Science & Fisheries Abstracts (ASFA), Artic & Antarctic Regions, BIOSIS, CAB Abstracts, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, EMBASE, Environment Index, Geobase, MEDLINE, Metadex, Pollution Abstracts, Veterinary Science Database, Civil Engineering Abstracts
• Keywords: Coastal eutrophication, Urea pollution and transformation, Phosphorus release, Phosphorus-solubilizing bacteria, Sediment pH, Oxidation of sediment, NITROGEN, CARBON
• Middle East Technical University Affiliated: No

Abstract

Increased urea is one of the common nitrogen forms polluting coastal waters and affecting nutrient dynamics. To investigate the effects of urea on sediment phosphorus (P) release, we carried out a 2-month mesocosm experiment with six targeted loadings of urea (0-0.6 mg N L-1 d(-1)). Results showed that: i) urea was rapidly transformed into ammonium and then nitrate (NO3-). ii) When nitrogen occurred as urea or ammonium, minor P release was observed. iii) After urea were mostly converted to NO3-, P release became clearer. iv) NO3- had a dual effect by promoting P release through decreasing sediment pH and increasing alkaline phosphatase activity or by inhibiting P release through improving sediment oxidation. v) The overall effects of urea on P release depended on the ultimate NO3- concentrations, being prominent when NO3- >= 11 mg N L-1. Our findings are of relevance when determining nitrogen reduction targets needed for combating eutrophication.