Occurrences, composition profiles and source identifications of polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ship ballast sediments.

The aim of this study was to investigate the levels of persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ship ballast sediments. The ballast sediment samples were collected from six merchant ships docked in 2015 in Jiangyin City, China. Ballast sediments represent a potential vector for the transport of POPs and invasive species between marine environments. An attempt was also made to determine the sources of these compounds in the ballast sediment. The results indicated ballast sediments generally contain greater amounts of BDE-209 and comparable amounts of PAHs, PBDEs (exclusive of BDE-209) and PCBs compared to those in marine surface sediments. Based on the sediment quality guidelines, PAHs and PCBs in ballast sediments were estimated to have median or high potential of posing ecological risks, respectively, to marine life if ballast sediments were disposed without specific treatment. POPs in ballast sediments were derived from multiple sources with atmospheric deposition being an important origin. Ship activities including diesel exhaust and illegal oil sewage discharge were considerable contributors of certain individual POPs to ballast sediments. Our study is important because it represents the first report on levels, health risk assessment and source apportionments of POPs in ballast sediments and is a first step in the implementation of specific ballast sediment management measures.

Landfill leachate pollutant removal performance of a novel biofilter packed with mixture medium.

Landfill leachate pollutants were treated in a biofilter filled with a mixture of aged refuse and slag, and the performance was compared with those reactors filled solely with either medium. Cultural counting method showed that bioreactor filled with slag had the highest amount of nitrifying bacteria, while polymerase chain reaction-denaturing gradient gel electrophoresis method showed that reactor filled with both media had the highest bacterial community diversity. Particle size distributions measurement showed that slag contained less fine particles than aged refuse, which provided better permeability. The reactor containing both media exhibited a high efficiency in removal of pollutants, and a higher resistance to shock loading and low temperature compared with single-medium reactors. It also overcame both the poor permeability of aged refuse filling and the low bacteria diversity of slag. The study shows that a mixture of aged refuse and slag as a new biofilter medium for leachate pollutant removal is technically viable.