Assessment of heavy metal release from dredged materials for different disposal scenarios: Study of Anzali international wetland, Iran

Autor: Parvin Berenjkar, Qiuyan Yuan, Mohsen Saeedi
Rok vydání: 2019
Předmět:
Zdroj: Process Safety and Environmental Protection. 132:94-104
ISSN: 0957-5820
Popis: In aquatic systems, heavy metals are accumulated in sediments that can release from loosely bound fractions during dredging and disposal operations. Five sediment samples were collected from the entry of the Pasikhan River to Anzali wetland, where dredging is carried out. The heavy metal distribution in sediments was determined using a sequential extraction procedure that showed Pb and Cd contribution mostly to non-residual phase (>80%). Heavy metal release from dredged materials was assessed for different disposal scenarios using pathway specific leaching tests. The highest release was attributed to Pb and Cd in open-water disposal (232 and 12.6 μg/L, respectively), confined disposal facilities (CDF) (180 and 12.2 μg/L, respectively), and landfilling (679 and 5.6 μg/L, respectively). The metal bioavailability and bioaccessibility were assessed using single extraction methods for agricultural use and other disposal scenarios. The metal bioavailability was in the order of Cd ∼ Pb > Cu > Mn > Zn > Fe > Ni > Cr. In case of open-water disposal, metal concentrations in water column were higher than water quality standards but lower than background amounts at the disposal site. In confined disposal, the concentrations in effluent and leachate of CDF occasionally exceeded the allowable limits. Finally, in case of landfilling, metal concentrations in leachate exceeded that of other methods, but remained below the USEPA recommended limits. According to implemented risk assessment indices, the risk level for heavy metal bioavailability and bioaccessibility was medium and very high, respectively, and Cr had carcinogenic and non-carcinogenic risk for human health.
Databáze: OpenAIRE
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