Influence of material composition on zinc, chromium and lead pollution of road-deposited sediments

The material composition of road-deposited sediments (RDS) collected from five different sites was measured, and its effects on the pollution of selected heavy metals (zinc, chromium, and lead) were revealed. Results indicated that RDS mainly consisted of quartz, amorphous materials, and inorganic minerals including silicates and carbonates. Due to the different material composition with solids in different size ranges, the unit specific surface area load of selected heavy metals indicated an increasing trend with increasing solid size. The influence of material composition of RDS on heavy metal pollution was further investigated. It was found that the presence of quartz indicated a negative effect on the pollution of zinc, chromium, and lead due to the electrically neutral characteristic of quartz. The amorphous content was positively related to the selected metal pollution because most of amorphous materials originated from traffic-related sources. In addition, the metal pollution was proportional to the content of inorganic minerals (silicates, carbonates) and some clay minerals due to their high surface area and usually negatively charged surface. Taken together, the material composition of RDS indicated a crucial influence on heavy metal pollution.