Seasonal variations, potential bioavailability, and ecological risk of phosphorus species in the coastal sediments of the Makran

Eutrophication and algal blooms occur frequently in coastal waters of the Makran, for which phosphorus is an important driving factor. Therefore, in this study, sequential extraction procedure was used to evaluate abun-dance of five phosphorus chemical species. Total phosphorus (TP) concentration ranged from 672.3 to 2031.9 mu g/g in pre-monsoon and 771.7 to 2095.7 mu g/g in post-monsoon. More than 87% of TP was inorganic P and contribution of organic phosphorus was low. Potential bioavailable P (PBAP) comprised of 52.1 and 35.5% of TP in the pre and post-monsoon, respectively. Average phosphorus pollution index was higher than one in all stations and seasons, implying that sediments in the study area are polluted by phosphorus and are under eutrophication risk. Thus, in the future, foregoing information will be important for assessment of phosphorus loading and pollution in the Makran.

Automated summary

The study revealed that eutrophication and algal blooms driven by phosphorus frequently occur in the coastal waters of Makran, with phosphorus mainly present in the form of inorganic species. The high phosphorus pollution index above one indicates that sediments in the area are contaminated with phosphorus, posing a risk of eutrophication.