آلودگی و ارزیابی ریسک اکولوژیک عناصر آرسنیک، کروم، نیکل، کبالت و سرب در رسوبات سطحی رودخانه مرداب و بخشی از ساحل دریای خزر، شهرستان آستارا

رودخانه مرداب در استان گیلان از رودخانه های مهمی است که در بالا دست شهر ساحلی آستارا تامین کننده آب کشاورزی برای مزارع شالی کاری است. این رودخانه در گذر از شهر آستارا همراه با دریافت پساب های شهری وارد دریای خزر می شود. از این رو فعالیت های کشاورزی و دریافت پساب های شهری می تواند باعث آلودگی آب و رسوب رودخانه مرداب شوند. در این تحقیق 22 نمونه رسوب سطحی در طول رودخانه و بخشی از ساحل دریای خزر که تحت تاثیر رودخانه مرداب است، جمع آوری و پس از آنالیز به منظور تعیین سطح آلودگی، منشا و ارزیابی ریسک اکولوژیک عناصر انتخابی مورد مطالعه قرار گرفتند. نتایج میانگین شاخص زمین انباشت، فاکتور غنی شدگی و فاکتور آلودگی بر اساس مقادیر زمینه محلی عناصر، آلودگی کم تا متوسط برای عناصر کبالت، آرسنیک، سرب و نیکل در رسوبات را نشان داد. میانگین غنی شدگی عناصر به ترتیب asas. enrichment factor values of cr were 30.26, 20.33 and 24.73 in samples of coastal park, safir-e-omid coast and sadaf coast, respectively. cr in the river sediment samples showed ef values higher than 2 as well, indicating the role of phosphate fertilizers in its enrichment in river sediments. ecological risk values for the studied elements, except cr, were in the safe range. cr showed moderate to significant pollution with high risk particularly at the confluence of the river with the sea and all the coastal samples. cr contamination in surface sediments of mordab river and coast of caspian sea revealed an anthropogenic source of this toxic element. regarding the results of this study, continuous monitoring of potentially toxic elements, especially cr, and sequential extraction analysis in sediments of mordab river and coast of caspian sea for accurate source apportionment and ecological/health risk assessment is necessary.

Contamination and ecological risk assessment of As, Cr, Ni, Co and Pb in surface sediments of Mordab River and a part of Caspian Sea cost, Astara County

Mordabb River in Gilan Province is one of the important rivers which supplies irrigation water for paddy farms in upstream of Astara coastal town. This river enters the Caspian Sea through the town of Astara after receiving urban effluents. Therefore, agricultural activities and receiving urban effluents would contaminate water and sediments of Mordab River. In this research 22 surface sediment samples were collected from the river and part of the Caspian Sea coast that is affected by the river, and after analysis were studied to determine pollution status, sources and ecological risk assessment of selected elements. The results of mean geoaccumulation index, enrichment factor and contamination factor based on the local baseline of elements, showed low to moderate pollution for the studied elements. As, Co, Pb and Ni revealed low to moderate enrichment. Mean enrichment of elements was as Cr>Pb>Ni>Co>As. Enrichment factor values of Cr were 30.26, 20.33 and 24.73 in samples of coastal park, Safir-e-omid coast and Sadaf coast, respectively. Cr in the river sediment samples showed EF values higher than 2 as well, indicating the role of phosphate fertilizers in its enrichment in river sediments. Ecological risk values for the studied elements, except Cr, were in the safe range. Cr showed moderate to significant pollution with high risk particularly at the confluence of the river with the sea and all the coastal samples. Cr contamination in surface sediments of Mordab River and coast of Caspian Sea revealed an anthropogenic source of this toxic element. Regarding the results of this study, continuous monitoring of potentially toxic elements, especially Cr, and sequential extraction analysis in sediments of Mordab River and coast of Caspian Sea for accurate source apportionment and ecological/health risk assessment is necessary.