High total organic carbon in surface waters of the northern Arabian Gulf: Implications for the oxygen minimum zone of the Arabian Sea

Mar Pollut Bull. 2018 Apr;129(1):35-42. doi: 10.1016/j.marpolbul.2018.02.013. Epub 2018 Feb 10.

Abstract

Measurements of total organic carbon (TOC) for two years in Kuwaiti waters showed high TOC levels (101.0-318.4, mean 161.2 μM) with maximal concentrations occurring within the polluted Kuwait Bay and decreasing offshore, indicating substantial anthropogenic component. Analysis of winter-time data revealed a large increase in density over the past four decades due to decrease in Shatt Al-Arab runoff, implying that the dissolved/suspended organic matter in surface waters of the northern Gulf could be quickly injected into the Gulf Deep Water (GDW). Our measurements together with an analysis of previously collected/published data suggest that the recent summer-time declining trend in oxygen in the GDW might be related to eutrophication. Higher preformed TOC and lower preformed dissolved oxygen contents of the high-salinity water mass that flows out of the Gulf and ventilates the mesopelagic oxygen minimum zone (OMZ) of the Northwestern Indian Ocean may cause expansion/intensification of the regional OMZ.

Keywords: Arabian Gulf; Eutrophication; Hypoxia; Kuwait Bay; Tigris-Euphrates Delta region; Total organic carbon.

MeSH terms

  • Environmental Monitoring / methods*
  • Eutrophication
  • Hydrocarbons / analysis*
  • Indian Ocean
  • Kuwait
  • Oxygen / analysis*
  • Seasons
  • Seawater / chemistry*
  • Water Pollutants, Chemical / analysis*

Substances

  • Hydrocarbons
  • Water Pollutants, Chemical
  • Oxygen