Risk assessment of the Incheh wetland based on geochemical indices (Golestan Province)

The Incheh wetland, with high ecological importance, is located in the north of Aq-Qala (Golestan province). In this study, the surface sediments of the Incheh wetland from 7 stations with a maximum depth of 2.8 m were collected in November 2018 to find the source and determine the amount of heavy metals pollutions in the wetland and calculate the indices of enrichment factor and pollution load. The water environmental parameters, heavy metals, grain size, and total organic matter were measured by portable multi-parameter meter, inductively-coupled plasma mass spectrometry, laser diffraction particle size analyzer, and oven combustion, respectively. The mean of Al and Fe in the sediments were 0.8±0.4 and 1.5±0.6%. Also, the mean of As, Cu, Ni, Pb, Cr, Zn and V in the samples were measured 2.8±4.6, 12.8±3.6, 26.7±6.4, 7.0±2.7, 25.7±7.8, 32.4±16.2 and 28.6±7.1 mg/kg, respectively. In general, in terms of the enrichment factor index, the wetland has low enrichment (1-1.8). In the case that station 5, in terms of Fe (3.7) and As (5.7) had moderate enrichment and moderate to severe enrichment, respectively. In terms of the range of pollution load index (0.46-0.84), all stations were less than 1, so they were not polluted. In general, due to the fact that the amount of nickel and arsenic in all stations and station 5 was higher than the TEL, respectively, it can be concluded that the probability of severe biological effects on most of benthic organisms is low and at the threshold level.