Coastal pollution due to increasing nutrient flux in aquaculture sites |
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Authors: | C P C David Y Y Sta Maria F P Siringan J M Reotita P B Zamora C L Villanoy E Z Sombrito and R V Azanza |
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Institution: | (1) National Institute of Geological Sciences, University of the Philippines Diliman, 1101 Quezon City, Philippines;(2) Marine Science Institute, University of the Philippines Diliman, 1101 Quezon City, Philippines;(3) Philippine Nuclear Research Institute, Department of Science and Technology, Commonwealth Avenue Diliman, 1101 Quezon City, Philippines |
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Abstract: | The supply of nitrogen and phosphorus in coastal zones through time is reflected in the nutrients’ concentration in the sediment
record. Five aquaculture sites in the Philippines were investigated in an effort to establish how long-term changes in land
and coastal water use could have led to biogeochemical modifications affecting the coastal ecosystem. Samples from study sites
show a narrow concentration range for nitrogen and did not reveal any significant trend through time. In contrast, phosphorus
concentrations in most sites start at less than 20 ppm in sediments 30 years and older. The phosphorus value continuously
increase in younger sediments, with each site having a different magnitude change as well as timing of when the major increase
happened. The uppermost 10 cm, representing the last 15 years in sites with age control, typically show a 2- to 3-fold increase
in P load values. Historical increase in nutrient load also coincides with harmful algal bloom events in each area; when effective
P input exceeded 130 kg/km2 per year. Lastly, the observed increase may be attributed to several factors including physical attributes of the area, urbanization
of coastal zones, but most importantly in the proliferation of aquaculture activities. |
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Keywords: | Algal blooms Aquaculture Phosphorus Sediments |
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