Assessment of bed sediment metal contamination in the Shadegan and Hawr Al Azim wetlands, Iran.

The Shadegan and Hawr Al Azim wetlands are important natural resources in southwestern Iran, yet relatively little work has been done to assess ecosystem health of the wetlands. Bed sediment from both wetlands was sampled in individual months between October, 2011 and December, 2012 and analyzed for As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb, and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES). The metals data were evaluated using a combination of sediment quality guidelines from the Ontario Ministry of Energy and Environment (MOEE, Canada), enrichment factors (EFs), and a geo-accumulation index (Igeo) approach. The sediments exceeded MOEE Lowest Effect Levels (LELs) consistently for Cr and Cu and a small proportion of samples (5%) for Hg. Levels of As, Cd, Fe, Pb, and Zn did not exceed LELs and none of the samples exceeded the Severe Effect Levels (SELs). In addition to the sediment guidelines, both the EF and Igeo calculations suggested levels of Mn and Fe were severely enriched, while the EF indicated Cd was slightly enriched. Metal levels in the Shadegan wetland exhibited both spatial and seasonal trends. Metal levels were greater near input areas from agricultural, urban, and industrial discharges and runoff as compared to the more remote and quiescent central part of the wetland. Except for Fe, the metal levels were greater in the wet season as compared to the dry season, perhaps due to greater stormwater runoff and sediment loads. This study provides baseline data which can be used to support development of appropriate contaminant source management strategies to help ensure conservation of these valuable wetland resources.

Study on the heavy metal bioconcentrations of the Shadegan international wetland mosquitofish, Gambusia affinis, by inductively coupled plasma technique.

The purpose of this study was to evaluate the levels of heavy metal bioconcentration of the mosquitofish (Gambusia affinis) in Shadegan international wetland. Sampling including the water, waterbed sediment and mosquitofish was carried out from the selected sampling sites during October and November 2011, and analyzed by the ICP-OES. Results show that the water has poor qualitative condition, according to EPA and WHO water quality standards. The level of the water Cr in the selected sites in both months and the levels of Fe, Mn and Zn during October in the SW1 site were higher than the instrumental detection limits indicating that the water was contaminated with these metals in the mentioned sites and months. The levels of the waterbed sediment As, Co, Cr, Cu, Fe, Mn, Pb and Zn, and mosquitofish Cr, Cu, Fe, Mn, Zn, Co and Cd were much higher than the instrumental detection limits, indicating that the waterbed sediment and mosquitofish were contaminated with them during October and November in the selected sites. Statistical assessments reveal that there is a significant difference between the mentioned contaminated water, waterbed sediment and mosquitofish heavy metals (all P-values < 0.05). In overall, it is considered that the contaminated heavy metals can be accumulated in the waterbed sediment and bioconcentrated in the wildlife tissues, then finally can be entered in the marine food chains and biomagnified there after long periods. In conclusion, this paper confirmed that the G. affinis can be used as a bioindicator of heavy metal pollution in marine ecosystems such as wetlands.