Sediment Characteristics and Estimation of Toxicity Site Specific Criteria for Sediments of Iranian Coasts, The Persian Gulf

Surface sediments from Iranian coasts of the Persian Gulf (n=121) were studied to track the spatial distribution of organic matter, carbonate level and grain size. The theoretical organic carbon (TOC) levels were among the high values ever reported, which suggested that the sediments possibly are dealing with impaired benthic fauna. A significant correlation was observed among water depth, TOM and carbonate levels as well as grainsize of the studied sediments (TOM(%)= 0.111water depth(m) + 0.025 (Sil+Clay) (%) -0.286Carbonate (%) + 15.441, adjusted R2= 0.898, p< 0.01). The studied region covered nearly 1% of the Persian Gulf’s surface area and contained heterogeneous spatial distribution for sedimentological factors. The examination of interpolated maps introduced the Pars Special Economic Energy Zone (PSEEZ) as a region with possibly high burdens of organic carbon and its co-occurring eco-pollutants. Benzo(a)pyrene and naphthalene site specific criteria were mapped. According to the maps, the intermediate zone and the Nayband Bay were much vulnerable against entering pollutants. It could be due to low levels of organic matter in the sediments of these regions. The sediment quality guidelines suggested that the biota of the ecologically and economically hot zone of the Iranian coast (EHZIC)is dealing with Bnzo(a)Pyrene and Naphthalene related adverse hazards, rarely and rarely-occasionally. Indicator kriging analysis and probability map proposed that Naphthalene related chronic toxicities are probable in the EHZIC. The highest probabilities were spatially distributed in the PSEEZ and the Nayband Bay. The ratios of Bezo (a)Pyrene to its site-specific criterion were significantly low and its release the toxic effects of B(a)P was not probable for the biota inhabited.

Keywords: Grainsize; Organic matter; Pars special economic energy zone; Persian gulf; Probability map; Sediment; Monitoring zones; Ecological and economical significance