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| Main Authors: | , , , , |
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| Format: | Artículo científico |
| Language: | en |
| Published: |
Marine pollution bulletin
2026
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| Subjects: | |
| Online Access: | https://pubmed.ncbi.nlm.nih.gov/41072165/ |
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Table of Contents:
- Phosphorus dynamics and fractionation in the Ashtamudi estuary, Southwest coast of India: Seasonal variability, and potential ecological risk assessment. Soman, Vishnuja Remani, Anjana Krishnankutty Suresh, Anju Venugopalan, Vishnu Kalladathvalappil Keedakkadan, Habeeb Rahman Phosphorus India Estuaries Environmental Monitoring Seasons Water Pollutants, Chemical Risk Assessment Geologic Sediments Wetlands Salinity As globally recognized biodiversity hotspots, Ramsar wetlands represent the intersection of environmental protection and sustainable development. Among the key elements maintaining their ecological balance, phosphorus (P) plays a central role in nutrient cycling and ecosystem production. This study presents the first geochemical assessment of phosphorus enrichment in the Ashtamudi estuary, a Ramsar wetland in Kerala, focusing on sediment-bound P fractions and their seasonal dynamics. Surface sediments were collected from 11 stations during two contrasting climatic regimes: the monsoon (June-September), characterized by high precipitation, freshwater inflow, and low salinity, whilethe pre-monsoon (March-May) was marked by dry conditions, limited runoff, and elevated salinity. A sequential chemical extraction was performed to quantify five phosphorus fractions: iron-bound phosphorus (Fe(OOH) ≈ P), calcium-bound P (CaCO₃ ≈ P), labile - organic phosphorus (ASOP), humic-bound organic phosphorus (Alk-OP), and residual organic phosphorus (ROP). The monsoon season exhibited the order Fe(OOH) ≈ P > CaCO₃ ≈ P > Alk-OP > ASOP > ROP, while in the pre-monsoon Alk-OP dominated, followed by Fe(OOH) ≈ P and CaCO₃ ≈ P. A sharp increase in dissolved inorganic phosphorus was observed in the study region with rising salinity. Low C/P and N/P ratios suggest an accumulation of phosphorus-enriched organic matter. The observed Corg/OP ratios (8.25-92.18) remained consistently lower than the Redfield ratio (106:1), suggesting elevated phosphorus content relative to carbon Bioavailable phosphorus(BAP) made up 64-67 % of TP in sediments, showing high P release potential to overlying waters and confirming sediments as a key internal P source driving eutrophication risk. The phosphorus enrichment index (PEI) greater than two pointed to a high risk of eutrophication in the region in both seasons. By addressing significant knowledge, this study provides a foundational understanding of phosphorus geochemistry in the Ashtamudi estuary and offers a framework for remediation regulation.