Scholarlink

<p>This study investigates the vertical distribution and geochemical fractions of phosphorus (P), sediment texture, and total organic carbon (TOC) in sediment cores collected from two contrasting backwaters (Sadras - SA and Edaiyur - ED) adjacent to the Kalpakkam coast, Tamil Nadu, southeast India. P was partitioned into its operationally defined forms: loosely bound P (LP), aluminium-bound P (AlP), iron-bound P (FeP), calcium-bound P (CaP), organic P (OP), and bioavailable P (BP) to evaluate sedimentary P dynamics and their ecological significance. The total P (TP) content varied from 537 to 2,384&#xa0;mg kg⁻¹ across depths (5–50&#xa0;cm), with depth-averaged values of 922&#xa0;mg kg⁻¹ in SA and 1,213&#xa0;mg kg⁻¹ in ED. The calculated Phosphorus Pollution Index (PPI) values exceeded 1.0 in both regions (SA = 1.5; ED = 2.0), indicating that the sediments are P-enriched and ecologically stressed. Sediment texture and P speciation diverged between the backwaters. SA sediments were sand-dominated with CaP contributing ~ 45% of TP, indicative of carbonate-mediated stabilization. On the other hand, ED sediments were organic-rich with OP comprising ~ 32% of TP and higher bioavailable P pools, reflecting higher organic matter input and diagenetic regeneration potential. TOC correlated strongly with Fe-bound, organic, and biologically available P (<i>r</i> &gt; 0.8), and depth-wise patterns suggested enhanced preservation of P and C in finer, low-energy layers. These findings demonstrate contrasting geochemical mechanisms of phosphorus retention and mobility—mineral stabilization in SA and organic/ redox-driven transformation in ED. The findings highlight the critical role of texture–TOC coupling and sedimentary processes in internal nutrient recycling and eutrophication risk in backwaters.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Vertical distribution and geochemical speciation of phosphorus in backwater sediments of the Kalpakkam coast, southeast India: Implications for internal loading and eutrophication risk

  • 期刊论文

  • 发表日期：

    2026年6月24日

查看全文
  • Ajit Kumar Mohanty,
  • Rengasamy Subramaniyan Sathishkumar,
  • Satyanarayan Bramha,
  • Annalakshmi Ozhimuthu

摘要

This study investigates the vertical distribution and geochemical fractions of phosphorus (P), sediment texture, and total organic carbon (TOC) in sediment cores collected from two contrasting backwaters (Sadras - SA and Edaiyur - ED) adjacent to the Kalpakkam coast, Tamil Nadu, southeast India. P was partitioned into its operationally defined forms: loosely bound P (LP), aluminium-bound P (AlP), iron-bound P (FeP), calcium-bound P (CaP), organic P (OP), and bioavailable P (BP) to evaluate sedimentary P dynamics and their ecological significance. The total P (TP) content varied from 537 to 2,384 mg kg⁻¹ across depths (5–50 cm), with depth-averaged values of 922 mg kg⁻¹ in SA and 1,213 mg kg⁻¹ in ED. The calculated Phosphorus Pollution Index (PPI) values exceeded 1.0 in both regions (SA = 1.5; ED = 2.0), indicating that the sediments are P-enriched and ecologically stressed. Sediment texture and P speciation diverged between the backwaters. SA sediments were sand-dominated with CaP contributing ~ 45% of TP, indicative of carbonate-mediated stabilization. On the other hand, ED sediments were organic-rich with OP comprising ~ 32% of TP and higher bioavailable P pools, reflecting higher organic matter input and diagenetic regeneration potential. TOC correlated strongly with Fe-bound, organic, and biologically available P (r > 0.8), and depth-wise patterns suggested enhanced preservation of P and C in finer, low-energy layers. These findings demonstrate contrasting geochemical mechanisms of phosphorus retention and mobility—mineral stabilization in SA and organic/ redox-driven transformation in ED. The findings highlight the critical role of texture–TOC coupling and sedimentary processes in internal nutrient recycling and eutrophication risk in backwaters.