Phosphorous speciation in surface sediments of the Cochin estuary

• Published in: Environmental monitoring and assessment Vol. 185; no. 3; pp. 2535 - 2552
• Main Authors: Gireeshkumar, T. R., Deepulal, P. M., Chandramohanakumar, N.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-03-2013; Springer; Springer Nature B.V
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Aquaculture; Atmospheric Protection/Air Quality Control/Air Pollution; Bioavailability; Biological and medical sciences; Biological and physicochemical phenomena; Brackish; Calcium; Carbon; Carbon - analysis; Chelating agents; Chemical extraction; Contaminated sediments; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental Monitoring; Estuaries; Eutrophication; Exact sciences and technology; Fresh Water - chemistry; Freshwater environments; Fundamental and applied biological sciences. Psychology; Geochemistry; Geologic Sediments - chemistry; Humic Substances - analysis; India; Iron; Mineralization; Monitoring/Environmental Analysis; Monsoons; Natural water pollution; Nitrogen - analysis; Organic carbon; Organic compounds; Organic loading; Organic matter; Phosphorus; Phosphorus - analysis; Pollution; Principal Component Analysis; Principal components analysis; Salinity; Seasonal variations; Seasons; Seawaters, estuaries; Sediment load; Sediments; Speciation; Studies; Sulfur; Water Pollutants, Chemical - analysis; Water Pollution, Chemical - statistics & numerical data; Water treatment and pollution; Wind; Asia; Kerala; India; ISW, India, Kerala, Ernakulam Dist., Cochin; ISW, India; Estuaries; Geochemistry; Phosphorous; Chemical extraction; Eutrophication; Environmental assessment; Pollutant behavior; Tropical zone; Phosphorus; Sediments; Chemistry; Environment impact; Water pollution; Environmental monitoring; Speciation
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-012-2729-3

Sequential chemical extraction using chelating agents were used to study the P dynamics and its bioavailability along the surface sediments of the Cochin estuary (southwest coast of India). Sediments were analyzed for major P species (iron bound P, calcium bound P, acid soluble organic P, alkali soluble organic P and residual organic P), Fe, Ca, total carbon, organic carbon, total nitrogen and total sulfur contents. An abrupt increase in the concentration of dissolved inorganic P with increasing salinity was observed in the study region. Iron-bound P exhibited a distinct seasonal pattern with maximum values in the monsoon season when fresh water condition was prevailed in the estuary. As salinity increased, the percentage of iron-bound P decreased, while that of calcium-bound P and total sedimentary sulfur increased. C/P and N/P ratios were low which indicate that large amounts of organic matter enriched with P tend to accumulate in surface sediments. The high organic P contribution in the sedimentary P pool may indicate high organic matter load with incomplete mineralization, as well as comparatively greater percentage of humic substance and resistant organic compounds. Principal component analysis is employed to find the possible processes influencing the speciation of P in the study region and indicate the following processes: (1) the spatial and seasonal variations of calcium bound P and acid soluble organic P was mainly controlled by sediment texture and organic carbon content, (2) sediment redox conditions control the distribution of iron bound P and (3) the terrigenous input of organic P is a significant processes controlling total P content in surface sediments. The bioavailable P was very high in the surface sediments which on an average accounts for 59 % in the pre-monsoon, 65 % in the monsoon and 53 % in the post-monsoon seasons. The surface sediments act as a potential internal source of P in the Cochin estuary.