علوم زیستی دریا
akram Bemanikharanagh; Alireza Riyahi Bakhtiari; Jahangard Mohammadi; R Taghizadeh Mehrjardi
Abstract
Shadegan wetland as largest wetland in Iran constantly exposed to hydrocarbons entering through the main entrance of the lagoon, including Jarahi river, outbursts of seasonal rivers from upstream, Persian Gulf tides from downstream, atmospheric deposition and possible leaks from oil pipelines. Considering ...
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Shadegan wetland as largest wetland in Iran constantly exposed to hydrocarbons entering through the main entrance of the lagoon, including Jarahi river, outbursts of seasonal rivers from upstream, Persian Gulf tides from downstream, atmospheric deposition and possible leaks from oil pipelines. Considering importance and extent of wetland and multiple sources of hydrocarbons, the aim of present study is to identify source and mapping of spatial distribution of polycyclic aromatic hydrocarbon (PAH) and n-alkanes using Geostatistics techniques. Sediment samples collected in at 202 stations at the top 5 cm of the sediment according to a systematic-random sampling design to cover whole wetland. The concentrations and compositions of hydrocarbons were analyzed by GC–MS. The spatial distribution of PAH for concentration and source mapped using total PAHand MP/P (Methylphenanthrene/Phenanthrene) index, respectively. Map of spatial distribution on concentration and Source of n-alkanes made based on total n-alkanes and CPI index, respectively. The ordinary kriging method applied for Spatial variability and interpolation of data in geostatistical study using GS+ and Arc GIS. Firstly normality of data was determined by using Kolmogorov – Smirnov test and after semi-variogram calculation, Spherical, Exponential and Gaussian models were fitted to each of heavy metals. RMSE parameter of Cross-Validation was used for model validity. The results of mapping analysis indicated that Shadegan wetland were strongly contaminated by petrogenic hydrocarbon source and 90% of the study area is subjected to chronic pollution of oil contaminants.