Fraction distribution and bioavailability of sediment heavy metals in the environment surrounding MSW landfill: a case study.

The aim of this study was to characterize the sediment samples from vicinity of a landfill in Qayen City, Iran. The samples were obtained from four different sampling stations. Sequential extraction was performed via a four-step procedure defined to evaluate the distribution of the element fraction in various samples. In the stations 3 and 4, Cd was found in large quantities during the first extraction F1, accounting for 40.4 and 38.7%, respectively. Pb was primarily presented in F2 of station 1 (approximately 44.80%), station 2 (approximately 41.8%), and station 4 (approximately 37.7%). Moreover, principal component analysis showed that heavy metal fraction in the sediment samples can be explained by two principal components (PCs). PC1 represented Cd, Cr, Ni, and Zn, while PC2 represented Pb and Cu. Pearson correlation coefficient indicated significant correlations in Cu-Pb, Zn-Cu, and Cr-Zn pairings. The present study concluded that the spatial distributions of sediment heavy metals were influenced by MSW landfill.

Sediment toxicity and ecological risk of trace metals from streams surrounding a municipal solid waste landfill.

The present study is an attempt to assess the pollution intensity and corresponding ecological risk of heavy metals such as Cd, Ni, Pb, Cu, Zn and Cr using various indices like geo-accumulation index, concentration factor, pollution loading and ecological risk index. In all 21 surface sediments samples were collected from the stream flowing around the solid waste disposal landfill of Qayen city in southeastern Iran. Although Igeo values for Cd varied greatly, sites 18-21 with class 5 show heavy loads of Cd (values between 4.13 and 4.45). PLI values (3.37-12.89) clearly suggest strong contamination with respect to the measured metals. This study clearly indicates that the contamination risk in the downstream reservoir is much higher than upstream sites due to transfer and accumulation of leached metals from upstream to downstream.