How does land use configuration influence on sediment heavy metal pollution? Comparison between riparian zone and sub-watersheds

The effect of land use on sediment quality depends on the spatial scale. It has been found that not only the type of land use but also the landscape characteristics has a significant impact on water quality ecosystem services provided by riparian zones including filtration of sediments and pollutants. In the present study, principal component analysis and hierarchical clustering were used to investigated the relationship between land use and landscape characteristic metrics with suspended and bed sediment heavy metal pollution at sub-watershed and multi-spatial buffer zone scales (250, 500, 750 and 1000 m) in Talar watershed. The results of multi-element sediment quality indices showed a high level of heavy metal pollution (As, Be, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag, Ti and Zn) for all 10 sampling points upstream and downstream of the study river. Irrigated agriculture and residential were two land uses showed the highest positive meaningful correlation with sediment heavy metals in 250 m buffer and sub-watershed, respectively. Furthermore, the results showed that the higher level of diversity and interspersion of land use patches, the more negative effect on sediment pollution. Our study outcomes could provide useful information for managers and policymakers in land planning and development to minimize river sediment pollution and preserve the health of water resources. Graphic abstract: [Figure not available: see fulltext.].