Skip to main content

Advertisement

Log in

Seasonal and Spatial Distribution of Phosphorus Fractions in Surface Sediments of the Southern Caspian Sea

  • Research Paper
  • Published:
Iranian Journal of Science Aims and scope Submit manuscript

Abstract

This study assesses seasonal fluctuations, spatial distribution and fractions of phosphorus (P) in the surface sediment layer of the southern Caspian Sea. Seasonal fluctuations were insignificant (p-value > 0.05) relative to the mean total P (TP) concentrations. Still, the highest levels were in autumn samples (1555 mg kg−1), followed by winter (1405 mg kg−1), spring (1378 mg kg−1), and summer (1130 mg kg−1). These minor temporal fluctuations in P concentrations are explained by seasonal differences in runoff amount and intensity of rivers discharging into the Caspian sea and thereby their sediment loading and physicochemical characteristics. The large riverine influx has led to TP contamination hotspots in the river deltas of Anzali wetland, Babolrood, and Sefidrud, where high loadings of suspended particles are discharged into the sea. The spatial distribution of TP is thus site-specific and uneven. The main P fraction was calcium-bound P (CaP), reflecting the phosphate (PO43−) strong affinity for, and association with, Ca-bearing minerals. Only a minor fraction of P was determined as loosely bound P (LP). The fraction of the mud size particles was the main explanatory factor for the spatial distribution of overall low levels of non-residual (or bioavailable) P forms (i.e., LP and iron- and aluminum- bound P: FeP and AlP, respectively) during spring and summer, while the sand fraction had strongest explanatory value for the distribution of residual (non-bioavailable) P form (CaP) during autumn and winter. This study demonstrates that P bioavailability in sediments is mainly governed by the physicochemical characteristics of the sediment material, which again is steered by seawater chemistry. A low content of bioavailable P fractions could therefore be explained by the relatively low content of fine-grained (< 63 µm, i.e., mud) particles in sediments of the southern Caspian Sea.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

Data Availability

All data generated or analyzed during this study are included in this published article [and its supplementary information files].

References

Download references

Acknowledgements

The authors state their gratitude to the Caspian Sea Ecology Research Center (CSERC) for support to do this study.

Funding

This work was supported by the Caspian Sea Ecology Research Center (CSERC).

Author information

Authors and Affiliations

Authors

Contributions

HNS helped in conceptualization, supervision, resources, project administration. MJN contributed to writing—original draft, conceptualization, formal analysis, validation, writing—review & editing. RDV was involved in validation, formal analysis, writing—review & editing. FV and MB performed methodology. PE helped in partial conceptualization, review & editing.

Corresponding author

Correspondence to Mohammad Javad Nematollahi.

Ethics declarations

Conflicts of interest

The authors declare that they have no conflict of interest.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 25 KB)

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Nasrollahzadeh Saravi, H., Nematollahi, M.J., Vogt, R.D. et al. Seasonal and Spatial Distribution of Phosphorus Fractions in Surface Sediments of the Southern Caspian Sea. Iran J Sci 47, 411–425 (2023). https://doi.org/10.1007/s40995-023-01426-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40995-023-01426-6

Keywords

Navigation