Spatial and temporal characterizations of seawater quality on marine waters area of the Persian Gulf

This research focuses on the spatial and temporal distribution of seawater quality factors such as dissolved oxygen (DO), chlorophyll a (Chl-a), salinity and temperature in the Persian Gulf (PG). The samplings were carried out on 11–34 stations during September 2018, May and November 2019. The range and average of Chl-a (μg/l) concentration in the surface waters were 0.04–1.10 (0.43 ± 0.25), 0.02–1.19 (0.46 ± 0.39) and 0.58–1.70 (0.93 ± 0.36) in the summer 2018, spring and autumn 2019, respectively. The cross-section of seawater salinity (psu), temperature (°C) and DO (mg/l) indicated strong stratification during late summer and autumn and vertically well-mixed structures in spring. Frequency distributions of DO at different levels indicated the incidence of a layer of minimum oxygen (0.85 mg/l) at depths below 50 meters in autumn. The distribution of Chl-a was also estimated using the remote sensor Moderate Resolution Imaging Spectrometer (MODIS) during 2018–2019. The results confirmed a significant covariation between remotely-sensed surface Chl-a and in situ data. The results showed that Chl-a was greater in regions nearby the coast compared to open sea regions and also significant impacts of the regional 2019 flooded on the Arvand River catchment.