Seasonal variations of density, mixed layer depth, nitrate, and phosphate in Noshahr area (based on seasonal sampling in 2012)

Arjmandi, Sedigheh; Nahavandian, Somayeh; Mahmoudi, Nemat; Saleh, Abolfazl

doi:10.22034/ijcoe.2026.523333.1177

Seasonal variations of density, mixed layer depth, nitrate, and phosphate in Noshahr area (based on seasonal sampling in 2012)

Articles in Press

Document Type : Original Research Article

Authors

Sedigheh Arjmandi ¹

Somayeh Nahavandian ²

Nemat Mahmoudi ³

Abolfazl Saleh ⁴

¹ Department of Marine Physics, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor

² Department of Environmental Science, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor

³ Department of Aquaculture, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor

⁴ Iranian National Institute for Oceanography and Atmospheric Science, Tehran, Iran

10.22034/ijcoe.2026.523333.1177

Abstract

This paper presents seasonal variations of various physical parameters including density and mixed layer depth (MLD) based on CTD measurements and nutrients (nitrate and phosphate) in the Noshahr area. The mixed layer depth was calculated based on density profiles using the threshold method with a threshold value of 0.5 kg.m-3. The maximum nitrate concentration was observed in the pycnocline during spring and summer. In fall, deepening of the MLD causes penetration of nitrate into the mixed layer and, together with the penetration of illumination, causes phytoplankton to bloom whom uses nitrate for their bloom. For this reason, in offshore areas up to a depth of 20 meters, the nitrate concentration in the water is low, while near the coast, the nitrate concentration is high. Our findings also indicate that in spring, in offshore areas, the phosphate concentration is high in the surface layer, while in summer and autumn, the maximum value is observed in the bed.

Keywords

Density

Mixed Layer Depth

Nitrate

Phosphate

Noshahr

Subjects